{"id":17267,"date":"2025-04-18T23:42:31","date_gmt":"2025-04-18T15:42:31","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/17267.html"},"modified":"2025-04-18T23:42:31","modified_gmt":"2025-04-18T15:42:31","slug":"%e3%80%90linux%e3%80%91%e3%80%90%e7%bd%91%e7%bb%9c%e3%80%91udp%e6%89%93%e6%b4%9e-%ef%bc%9e%e4%b8%8d%e5%90%8c%e5%ad%90%e7%bd%91%e4%b8%8b%e7%9a%84%e5%ae%a2%e6%88%b7%e7%ab%af%e5%92%8c%e6%9c%8d%e5%8a%a1","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/17267.html","title":{"rendered":"\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e--\uff1e\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1\uff08\u6210\u529f\u7248\uff09"},"content":{"rendered":"<p>\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e\u2013&#xff1e;\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1&#xff08;\u6210\u529f\u7248&#xff09; \u6839\u636e\u4e0a\u4e2a\u6587\u7ae0\u7684\u5206\u6790 \u95ee\u9898\u53ef\u80fd\u51fa\u73b0\u5728\u4ee3\u7801\u903b\u8f91\u4e0a\u9762 \u6211\u8fd9\u91cc\u91cd\u65b0\u67e5\u627e\u8d44\u6599\u6000\u7591&#xff1a;<\/p>\n<p>1 NAT\u6620\u5c04\u53ef\u80fd\u9700\u8981\u591a\u6b21\u6570\u636e\u5305\u7684\u53d1\u9001\u624d\u80fd\u5efa\u7acb\u3002<\/p>\n<p>2 NAT\u6620\u5c04\u4fdd\u5b58\u65f6\u95f4\u592a\u77ed&#xff0c;\u5e76\u4e14 NAT \u53ef\u80fd\u4f1a\u5728\u77ed\u65f6\u95f4\u5185\u6539\u53d8\u8fd9\u4e9b\u6620\u5c04&#xff0c;\u9700\u8981\u4e00\u76f4\u4fdd\u6301\u6620\u5c04\u3002<\/p>\n<ul>\n<li>\n<p>\u6709\u4e9b NAT \u8bbe\u5907\u4f1a\u56e0\u4e3a\u77ed\u65f6\u95f4\u5185\u6ca1\u6709\u6570\u636e\u800c\u56de\u6536\u7aef\u53e3\u6620\u5c04&#xff0c;\u5bfc\u81f4\u670d\u52a1\u5668\u63d0\u4f9b\u7684 IP:Port \u5931\u6548\u3002<\/p>\n<\/li>\n<li>\n<p>\u4fdd\u6d3b\u673a\u5236&#xff1a;\u53cc\u65b9\u5b9a\u671f\u53d1\u9001\u4fdd\u6d3b\u5305\u4ee5\u9632 NAT \u8d85\u65f6\u5173\u95ed\u6620\u5c04\u3002<\/p>\n<\/li>\n<\/ul>\n<p>3 \u670d\u52a1\u5668\u53ea\u662f\u5411\u53cc\u65b9\u53d1\u9001\u4e86IP\u548c\u7aef\u53e3\u540e\u76f4\u63a5\u9000\u51fa\u4e86&#xff0c;\u5e76\u672a\u53d1\u9001\u6570\u636e\u5305\u7ed9\u5ba2\u6237\u7aef&#xff0c;\u5bfc\u81f4NAT \u8bbe\u5907\u672a\u5efa\u7acb\u6620\u5c04 &#xff08;\u670d\u52a1\u5668\u53ea\u53d1\u9001\u4e86\u4e00\u6b21\u6570\u636e&#xff0c;\u4f46\u90e8\u5206 NAT \u8bbe\u5907\u9700\u8981\u591a\u6b21\u4ea4\u4e92\u624d\u4f1a\u521b\u5efa\u6620\u5c04&#xff0c;\u4e00\u4e9b NAT \u9700\u8981\u6536\u5230\u5916\u90e8\u6570\u636e\u5305\u540e\u624d\u4f1a\u4fdd\u6301\u6620\u5c04\u3002&#xff09;<\/p>\n<p>4 \u6211\u5728\u4ee3\u7801\u4e2d\u7ed1\u5b9a\u4e86\u56fa\u5b9a\u7aef\u53e3&#xff0c;NAT\u5185\u90e8\u53ef\u80fd\u4f1a\u6709\u81ea\u5df1\u7684\u5b9e\u73b0&#xff0c;\u8ba9\u7cfb\u7edf\u81ea\u5df1\u5206\u914d\u7aef\u53e3\u53ef\u80fd\u66f4\u5408\u9002<\/p>\n<p>5 \u9700\u8981\u53cc\u65b9\u5728\u83b7\u5f97\u5bf9\u65b9\u516c\u7f51\u5730\u5740\u540e&#xff0c;\u7acb\u5373\u5411\u5bf9\u65b9\u53d1\u9001\u201c\u6572\u95e8\u201d\u6570\u636e\u5305&#xff0c;\u4ee5\u4fbf\u5404\u81ea\u7684 NAT \u5efa\u7acb\u6620\u5c04\u3002<\/p>\n<ul>\n<li>NAT \u8bbe\u5907\u901a\u5e38\u53ea\u5141\u8bb8\u66fe\u7ecf\u4e3b\u52a8\u53d1\u9001\u6570\u636e\u7ed9\u5bf9\u65b9\u7684\u5730\u5740\u63a5\u6536\u6570\u636e\u3002<\/li>\n<li>\u5ba2\u6237\u7aef\u7b2c\u4e00\u6b21sendto()\u7684\u6570\u636e\u5305\u4f1a\u88ab\u4e22\u6389 \u540e\u7eed\u624d\u80fd\u6b63\u786e\u901a\u4fe1<\/li>\n<\/ul>\n<hr \/>\n<p>\u8fd9\u91cc\u8d34\u4e00\u4e0budp\u901a\u4fe1\u63a5\u53e3 <img decoding=\"async\" src=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2025\/04\/20250418154229-680272e5a8112.png\" alt=\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \/><\/p>\n<h3>\u6574\u4f53\u6d41\u7a0b<\/h3>\n<h4>1. \u6ce8\u518c\u9636\u6bb5<\/h4>\n<ul>\n<li>\n<p>\u5ba2\u6237\u7aef\u52a8\u4f5c&#xff1a;<\/p>\n<ul>\n<li>\u6bcf\u4e2a\u5ba2\u6237\u7aef&#xff08;C1 \u548c C2&#xff09;\u542f\u52a8\u65f6\u521b\u5efa\u81f3\u5c11\u4e00\u4e2a UDP \u5957\u63a5\u5b57&#xff08;\u6709\u4e9b\u5b9e\u73b0\u4e2d\u4e3a\u4e86\u9694\u79bb\u63a7\u5236\u4e0e\u6570\u636e\u53ef\u80fd\u521b\u5efa\u4e24\u4e2a&#xff0c;\u4f46\u6700\u5173\u952e\u7684\u662f&#xff1a;\n<ul>\n<li>\u7528\u4e8e\u5411\u670d\u52a1\u5668\u53d1\u9001\u6ce8\u518c\u6d88\u606f&#xff0c;\u5e76\u63a5\u6536\u670d\u52a1\u5668\u8fd4\u56de\u7684\u4fe1\u606f&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u5ba2\u6237\u7aef\u5411\u670d\u52a1\u5668\u53d1\u9001\u6ce8\u518c\u6d88\u606f&#xff08;\u4f8b\u5982 \u201cHELLO\u201d&#xff09;\u3002<\/li>\n<li>\u6b64\u65f6&#xff0c;\u901a\u8fc7\u8c03\u7528 recvfrom()&#xff0c;\u670d\u52a1\u5668\u80fd\u591f\u83b7\u5f97\u5ba2\u6237\u7aef\u53d1\u9001\u6570\u636e\u65f6\u7684\u6e90\u5730\u5740\u4fe1\u606f&#xff0c;\u5373 NAT \u6620\u5c04\u540e\u7684\u516c\u7f51 IP \u548c\u7aef\u53e3\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u670d\u52a1\u5668\u52a8\u4f5c&#xff1a;<\/p>\n<ul>\n<li>\u670d\u52a1\u5668\u542f\u52a8\u540e\u521b\u5efa\u4e00\u4e2a UDP \u5957\u63a5\u5b57\u5e76\u7ed1\u5b9a\u5230\u56fa\u5b9a\u7aef\u53e3&#xff08;\u4f8b\u5982 50001&#xff09;\u3002<\/li>\n<li>\u670d\u52a1\u5668\u5faa\u73af\u7b49\u5f85\u63a5\u6536\u5ba2\u6237\u7aef\u7684\u6ce8\u518c\u6d88\u606f&#xff0c;\u540c\u65f6\u8bb0\u5f55\u6bcf\u4e2a\u5ba2\u6237\u7aef\u7684\u516c\u7f51\u6620\u5c04\u5730\u5740&#xff08;\u4ece recvfrom \u8fd4\u56de\u7684 sockaddr \u4fe1\u606f\u4e2d\u83b7\u5f97&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<hr \/>\n<h4>2. \u5730\u5740\u4ea4\u6362\u9636\u6bb5<\/h4>\n<ul>\n<li>\u670d\u52a1\u5668\u7aef&#xff1a;\n<ul>\n<li>\u7528\u4e8e\u5b58\u50a8\u4e24\u4e2a\u5ba2\u6237\u7aef\u7684\u5730\u5740\u4fe1\u606f\u548c\u5f53\u524d\u6ce8\u518c\u7684\u5ba2\u6237\u7aef\u6570\u91cf&#xff08;\u4f8b\u5982\u4f7f\u7528\u6570\u7ec4 struct sockaddr_in clientAddrs[2] \u548c\u8ba1\u6570\u5668 clientCount&#xff09;\u3002<\/li>\n<li>\u5f53\u670d\u52a1\u5668\u63a5\u6536\u5230\u4e24\u4e2a\u5ba2\u6237\u7aef\u7684\u6ce8\u518c\u6d88\u606f\u540e&#xff08;\u6bd4\u5982\u4e24\u6761 \u201cHELLO\u201d \u6d88\u606f&#xff09;&#xff0c;\u670d\u52a1\u5668\u5c06\u8fd9\u4e24\u4e2a\u5ba2\u6237\u7aef\u7684\u516c\u7f51\u6620\u5c04\u5730\u5740\u4e92\u6362&#xff1a;\n<ul>\n<li>\u5411\u5ba2\u6237\u7aef1\u53d1\u9001\u6d88\u606f&#xff0c;\u683c\u5f0f\u4f8b\u5982 &#034;PEER &lt;C2\u516c\u7f51IP&gt;^&lt;C2\u6620\u5c04\u7aef\u53e3&gt;&#034;&#xff1b;<\/li>\n<li>\u5411\u5ba2\u6237\u7aef2\u53d1\u9001\u6d88\u606f&#xff0c;\u683c\u5f0f\u4f8b\u5982 &#034;PEER &lt;C1\u516c\u7f51IP&gt;^&lt;C1\u6620\u5c04\u7aef\u53e3&gt;&#034;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u4e3a\u786e\u4fdd NAT \u6620\u5c04\u6301\u7eed\u6709\u6548&#xff08;\u907f\u514d\u8d85\u65f6\u5173\u95ed&#xff09;&#xff0c;\u670d\u52a1\u5668\u8fd8\u53ef\u4ee5\u518d\u989d\u5916\u5411\u4e24\u4e2a\u5ba2\u6237\u7aef\u53d1\u9001\u63a2\u6d4b\u6570\u636e\u5305&#xff08;\u5982 \u201cping\u201d&#xff09;&#xff0c;\u6fc0\u6d3b\u53cc\u65b9\u7684 NAT \u6620\u5c04\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<hr \/>\n<h4>3. NAT \u6253\u6d1e\u9636\u6bb5<\/h4>\n<ul>\n<li>\u5ba2\u6237\u7aef&#xff08;C1 \u548c C2&#xff09;&#xff1a;\n<ul>\n<li>\u5728\u6536\u5230\u670d\u52a1\u5668\u8fd4\u56de\u7684\u5305\u542b\u5bf9\u65b9\u516c\u7f51\u6620\u5c04\u5730\u5740\u7684\u4fe1\u606f\u540e&#xff0c;\u6bcf\u4e2a\u5ba2\u6237\u7aef\u89e3\u6790\u51fa\u5bf9\u65b9\u7684\u516c\u7f51 IP \u548c\u6620\u5c04\u7aef\u53e3\u3002<\/li>\n<li>\u7136\u540e&#xff0c;\u5ba2\u6237\u7aef\u7acb\u5373\u5411\u5bf9\u65b9\u53d1\u9001\u4e00\u4e2a\u201c\u6572\u95e8\u201d\u6570\u636e\u5305&#xff08;\u4f8b\u5982 \u201cknock\u201d \u6216 \u201cping\u201d&#xff09;&#xff0c;\u76ee\u7684\u662f&#xff1a;\n<ul>\n<li>\u4e3b\u52a8\u89e6\u53d1\u81ea\u5df1 NAT \u8bbe\u5907\u5efa\u7acb\u5411\u5bf9\u65b9\u7684\u6620\u5c04&#xff0c;<\/li>\n<li>\u540c\u65f6\u6fc0\u6d3b\u5bf9\u65b9 NAT \u4e2d\u5173\u4e8e\u672c\u7aef\u53d1\u9001\u6570\u636e\u7684\u6620\u5c04\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u53cc\u65b9\u4e92\u53d1\u201c\u6572\u95e8\u201d\u5305\u540e&#xff0c;\u5404\u81ea\u7684 NAT \u8bbe\u5907\u5c31\u4f1a\u5141\u8bb8\u5bf9\u65b9\u8fd4\u56de\u6570\u636e&#xff0c;\u5373\u4f7f\u4e4b\u524d\u8fd8\u6ca1\u6709\u771f\u6b63\u5efa\u7acb\u8d77\u6b63\u5f0f\u7684\u6570\u636e\u901a\u4fe1\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<hr \/>\n<h4>4. \u53cc\u5411\u901a\u4fe1\u9636\u6bb5<\/h4>\n<ul>\n<li>\n<p>\u5efa\u7acb\u901a\u4fe1&#xff1a;<\/p>\n<ul>\n<li>\u53cc\u65b9\u5747\u4f7f\u7528\u670d\u52a1\u5668\u8fd4\u56de\u7684\u5730\u5740&#xff08;\u5373\u5404\u81ea NAT \u6620\u5c04\u540e\u7684\u516c\u7f51 IP \u548c\u7aef\u53e3&#xff09;\u4f5c\u4e3a\u76ee\u6807\u5730\u5740\u6765\u53d1\u9001\u6570\u636e\u5305\u3002<\/li>\n<li>\u5ba2\u6237\u7aef\u8fdb\u5165\u4e00\u4e2a\u5faa\u73af&#xff1a;\n<ul>\n<li>\u5b9a\u65f6&#xff08;\u4f8b\u5982\u6bcf 500ms \u6216\u6bcf 5 \u79d2&#xff09;\u5411\u5bf9\u65b9\u53d1\u9001\u6570\u636e\u5305&#xff08;\u8fd9\u53ef\u4ee5\u662f\u7528\u6237\u8f93\u5165\u7684\u6d88\u606f&#xff0c;\u4e5f\u53ef\u4ee5\u662f\u4fdd\u6d3b\u6570\u636e&#xff0c;\u5982 \u201cKEEP_ALIVE\u201d&#xff09;&#xff0c;<\/li>\n<li>\u540c\u65f6\u63a5\u6536\u5bf9\u65b9\u7684\u56de\u590d&#xff0c;\u4ece\u800c\u786e\u8ba4\u901a\u4fe1\u901a\u9053\u5df2\u5efa\u7acb\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u4fdd\u6d3b\u673a\u5236&#xff1a;<\/p>\n<ul>\n<li>\u4e3a\u9632\u6b62 NAT \u6620\u5c04\u56e0\u957f\u65f6\u95f4\u65e0\u6570\u636e\u800c\u8d85\u65f6\u5173\u95ed&#xff0c;\u6bcf\u4e2a\u5ba2\u6237\u7aef\u53ef\u542f\u52a8\u72ec\u7acb\u7684\u4fdd\u6d3b\u7ebf\u7a0b&#xff0c;\u5b9a\u65f6\u5411\u5bf9\u65b9\u53d1\u9001\u201c\u4fdd\u6d3b\u5305\u201d&#xff0c;\u786e\u4fdd\u6620\u5c04\u6301\u7eed\u6709\u6548\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<hr \/>\n<h3>\u4ee3\u7801<\/h3>\n<h4>server.cpp<\/h4>\n<p><span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;iostream&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;cstring&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;unistd.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;arpa\/inet.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;errno.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;pthread.h&gt;<\/span><\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u5b9a\u4e49\u670d\u52a1\u5668\u76d1\u542c\u7aef\u53e3\u548c\u7f13\u51b2\u533a\u5927\u5c0f<\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">define<\/span> <span class=\"token macro-name\">SERVER_PORT<\/span> <span class=\"token expression\"><span class=\"token number\">50001<\/span><\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">define<\/span> <span class=\"token macro-name\">BUF_SIZE<\/span> <span class=\"token expression\"><span class=\"token number\">1024<\/span><\/span><\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u5168\u5c40\u53d8\u91cf&#xff1a;\u7528\u4e8e\u5b58\u50a8\u4e24\u4e2a\u5ba2\u6237\u7aef\u7684\u5730\u5740\u4fe1\u606f\u548c\u5f53\u524d\u6ce8\u518c\u7684\u5ba2\u6237\u7aef\u6570\u91cf<\/span><br \/>\n<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token keyword\">int<\/span> clientCount <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u4e92\u65a5\u9501\u4fdd\u62a4\u5bf9 clientAddrs \u548c clientCount \u7684\u8bbf\u95ee<\/span><br \/>\npthread_mutex_t clients_mutex <span class=\"token operator\">&#061;<\/span> PTHREAD_MUTEX_INITIALIZER<span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">int<\/span> <span class=\"token function\">main<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">int<\/span> sockfd<span class=\"token punctuation\">;<\/span>                <span class=\"token comment\">\/\/ UDP \u5957\u63a5\u5b57\u63cf\u8ff0\u7b26<\/span><br \/>\n    <span class=\"token keyword\">char<\/span> buffer<span class=\"token punctuation\">[<\/span>BUF_SIZE<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span>     <span class=\"token comment\">\/\/ \u7528\u4e8e\u63a5\u6536\u6570\u636e\u7684\u7f13\u51b2\u533a<\/span><br \/>\n    <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> serverAddr<span class=\"token punctuation\">,<\/span> clientAddr<span class=\"token punctuation\">;<\/span><br \/>\n    socklen_t addrLen <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>clientAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 1. \u521b\u5efa UDP \u5957\u63a5\u5b57<\/span><br \/>\n    sockfd <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">socket<\/span><span class=\"token punctuation\">(<\/span>AF_INET<span class=\"token punctuation\">,<\/span> SOCK_DGRAM<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>sockfd <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Server: Socket creation error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 2. \u8bbe\u7f6e\u5e76\u521d\u59cb\u5316\u670d\u52a1\u5668\u5730\u5740\u7ed3\u6784\u4f53<\/span><br \/>\n    <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>serverAddr<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>serverAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    serverAddr<span class=\"token punctuation\">.<\/span>sin_family <span class=\"token operator\">&#061;<\/span> AF_INET<span class=\"token punctuation\">;<\/span>              <span class=\"token comment\">\/\/ IPv4<\/span><br \/>\n    serverAddr<span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">.<\/span>s_addr <span class=\"token operator\">&#061;<\/span> INADDR_ANY<span class=\"token punctuation\">;<\/span>        <span class=\"token comment\">\/\/ \u63a5\u53d7\u4efb\u610fIP<\/span><br \/>\n    serverAddr<span class=\"token punctuation\">.<\/span>sin_port <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">htons<\/span><span class=\"token punctuation\">(<\/span>SERVER_PORT<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>       <span class=\"token comment\">\/\/ \u7ed1\u5b9a\u5230 SERVER_PORT<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 3. \u7ed1\u5b9a\u5957\u63a5\u5b57\u5230\u6307\u5b9a\u5730\u5740\u548c\u7aef\u53e3<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">bind<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>serverAddr<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>serverAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Server: Bind error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Server is running on port &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> SERVER_PORT <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;. Waiting for clients&#8230;&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 4. \u8fdb\u5165\u65e0\u9650\u5faa\u73af&#xff0c;\u4e0d\u65ad\u63a5\u6536\u5ba2\u6237\u7aef\u6d88\u606f<\/span><br \/>\n    <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token boolean\">true<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u6e05\u7a7a\u7f13\u51b2\u533a&#xff0c;\u51c6\u5907\u63a5\u6536\u65b0\u7684\u6570\u636e<\/span><br \/>\n        <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u4f7f\u7528 recvfrom \u63a5\u6536\u5ba2\u6237\u7aef\u6570\u636e&#xff0c;\u540c\u65f6\u83b7\u53d6\u53d1\u9001\u8005\u5730\u5740<\/span><br \/>\n        <span class=\"token keyword\">int<\/span> n <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">recvfrom<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> buffer<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddr<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>addrLen<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Server: recvfrom error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">continue<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        buffer<span class=\"token punctuation\">[<\/span>n<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token char\">&#039;\\\\0&#039;<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u786e\u4fdd\u6570\u636e\u4ee5\u5b57\u7b26\u4e32\u5f62\u5f0f\u7ed3\u675f<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Received from client: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> buffer <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034; from &#034;<\/span><br \/>\n            <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">inet_ntoa<\/span><span class=\"token punctuation\">(<\/span>clientAddr<span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;:&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">ntohs<\/span><span class=\"token punctuation\">(<\/span>clientAddr<span class=\"token punctuation\">.<\/span>sin_port<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u52a0\u9501\u540e\u5904\u7406\u5ba2\u6237\u7aef\u6ce8\u518c\u6570\u636e<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_lock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>clients_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u5f53\u6536\u5230 &#034;HELLO&#034; \u6d88\u606f\u4e14\u5f53\u524d\u6ce8\u518c\u5ba2\u6237\u7aef\u6570\u4e0d\u8db3 2 \u65f6&#xff0c;\u4fdd\u5b58\u5ba2\u6237\u7aef\u5730\u5740\u4fe1\u606f<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">strcmp<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;HELLO&#034;<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span> <span class=\"token operator\">&amp;&amp;<\/span> clientCount <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            clientAddrs<span class=\"token punctuation\">[<\/span>clientCount<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> clientAddr<span class=\"token punctuation\">;<\/span><br \/>\n            clientCount<span class=\"token operator\">&#043;&#043;<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>            <span class=\"token comment\">\/\/ \u56de\u590d ACK \u7ed9\u6ce8\u518c\u7684\u5ba2\u6237\u7aef&#xff0c;\u786e\u8ba4\u6536\u5230\u6d88\u606f<\/span><br \/>\n            <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> ack <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#034;ACK&#034;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> ack<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>ack<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddr<span class=\"token punctuation\">,<\/span> addrLen<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u5982\u679c\u4e24\u4e2a\u5ba2\u6237\u7aef\u90fd\u5df2\u6ce8\u518c&#xff0c;\u4ea4\u6362\u5b83\u4eec\u7684\u516c\u7f51\u6620\u5c04\u5730\u5740\u4fe1\u606f<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>clientCount <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token keyword\">char<\/span> msg<span class=\"token punctuation\">[<\/span>BUF_SIZE<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">{<\/span> <span class=\"token number\">0<\/span> <span class=\"token punctuation\">}<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token comment\">\/\/ \u6784\u9020\u53d1\u9001\u7ed9\u5ba2\u6237\u7aef1\u7684\u6d88\u606f&#xff1a;\u5305\u542b\u5ba2\u6237\u7aef2\u7684\u516c\u7f51IP\u548c\u6620\u5c04\u7aef\u53e3&#xff0c;\u683c\u5f0f\u4e3a &#034;PEER &lt;ip&gt; &lt;port&gt;&#034;<\/span><br \/>\n            <span class=\"token function\">snprintf<\/span><span class=\"token punctuation\">(<\/span>msg<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;PEER %s %d&#034;<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token function\">inet_ntoa<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token function\">ntohs<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">.<\/span>sin_port<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> msg<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>msg<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Sent to client1: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> msg <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>            <span class=\"token comment\">\/\/ \u6784\u9020\u53d1\u9001\u7ed9\u5ba2\u6237\u7aef2\u7684\u6d88\u606f&#xff1a;\u5305\u542b\u5ba2\u6237\u7aef1\u7684\u516c\u7f51IP\u548c\u6620\u5c04\u7aef\u53e3<\/span><br \/>\n            <span class=\"token function\">snprintf<\/span><span class=\"token punctuation\">(<\/span>msg<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;PEER %s %d&#034;<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token function\">inet_ntoa<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token function\">ntohs<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">.<\/span>sin_port<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> msg<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>msg<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n                <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Sent to client2: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> msg <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>            <span class=\"token comment\">\/\/ \u4e3a\u4fdd\u6301 NAT \u6620\u5c04\u6709\u6548&#xff0c;\u53ef\u9009&#xff1a;\u670d\u52a1\u5668\u989d\u5916\u53d1\u9001\u201cping\u201d\u5305\u7ed9\u53cc\u65b9<\/span><br \/>\n            <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;ping&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">4<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;ping&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">4<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>clientAddrs<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>            <span class=\"token comment\">\/\/ \u91cd\u7f6e\u5ba2\u6237\u7aef\u8ba1\u6570&#xff0c;\u7b49\u5f85\u4e0b\u4e00\u7ec4\u5ba2\u6237\u7aef\u6ce8\u518c<\/span><br \/>\n            clientCount <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_unlock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>clients_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<hr \/>\n<li>\n<p>\u5934\u6587\u4ef6\u5305\u542b\u4e0e\u5b8f\u5b9a\u4e49<\/p>\n<ul>\n<li>\u5305\u542b\u4e86\u7f51\u7edc\u7f16\u7a0b\u3001\u5b57\u7b26\u4e32\u64cd\u4f5c\u3001\u7ebf\u7a0b\u548c\u9519\u8bef\u5904\u7406\u6240\u9700\u7684\u5934\u6587\u4ef6\u3002<\/li>\n<li>\u5b9a\u4e49\u4e86\u670d\u52a1\u5668\u7aef\u53e3&#xff08;50001&#xff09;\u548c\u7f13\u51b2\u533a\u5927\u5c0f&#xff08;1024\u5b57\u8282&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5168\u5c40\u53d8\u91cf\u58f0\u660e<\/p>\n<ul>\n<li>clientAddrs[2] \u7528\u4e8e\u5b58\u50a8\u4e24\u4e2a\u5ba2\u6237\u7aef\u7684\u5730\u5740\u3002<\/li>\n<li>clientCount \u8bb0\u5f55\u5df2\u6ce8\u518c\u7684\u5ba2\u6237\u7aef\u6570\u91cf\u3002<\/li>\n<li>\u4f7f\u7528 clients_mutex \u4fdd\u62a4\u8fd9\u4e9b\u5171\u4eab\u53d8\u91cf\u7684\u5e76\u53d1\u8bbf\u95ee\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u4e3b\u51fd\u6570\u5f00\u59cb<\/p>\n<ul>\n<li>\u521b\u5efa UDP \u5957\u63a5\u5b57&#xff0c;\u5e76\u68c0\u67e5\u662f\u5426\u6210\u529f&#xff1b;\u82e5\u5931\u8d25\u5219\u6253\u5370\u9519\u8bef\u4fe1\u606f\u5e76\u9000\u51fa\u3002<\/li>\n<li>\u521d\u59cb\u5316\u670d\u52a1\u5668\u5730\u5740\u7ed3\u6784\u4f53&#xff08;IPv4\u3001\u4efb\u610f\u5730\u5740\u3001\u7aef\u53e3\u8f6c\u6362\u4e3a\u7f51\u7edc\u5b57\u8282\u5e8f&#xff09;\u3002<\/li>\n<li>\u7ed1\u5b9a\u5957\u63a5\u5b57\u5230\u670d\u52a1\u5668\u5730\u5740\u3002\u5982\u679c\u7ed1\u5b9a\u5931\u8d25\u5219\u9000\u51fa\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u6253\u5370\u670d\u52a1\u5668\u542f\u52a8\u4fe1\u606f<\/p>\n<ul>\n<li>\u8f93\u51fa\u670d\u52a1\u5668\u5df2\u542f\u52a8\u5e76\u76d1\u542c\u7684\u63d0\u793a\u4fe1\u606f\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u8fdb\u5165\u65e0\u9650\u5faa\u73af&#xff0c;\u63a5\u6536\u5ba2\u6237\u7aef\u6d88\u606f<\/p>\n<ul>\n<li>\u6bcf\u6b21\u5faa\u73af\u5f00\u59cb\u524d\u6e05\u7a7a\u7f13\u51b2\u533a\u3002<\/li>\n<li>\u8c03\u7528 recvfrom() \u63a5\u6536\u5ba2\u6237\u7aef\u6570\u636e&#xff0c;\u5e76\u586b\u5145\u5ba2\u6237\u7aef\u5730\u5740&#xff08;\u5373 NAT \u6620\u5c04\u7684\u516c\u7f51\u5730\u5740&#xff09;\u3002<\/li>\n<li>\u6253\u5370\u63a5\u6536\u5230\u7684\u6d88\u606f\u548c\u5ba2\u6237\u7aef\u5730\u5740&#xff08;\u8f6c\u6362\u4e3a\u70b9\u5206\u5341\u8fdb\u5236 IP \u4e0e\u4e3b\u673a\u5b57\u8282\u5e8f\u7684\u7aef\u53e3&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5ba2\u6237\u7aef\u6ce8\u518c\u5904\u7406&#xff08;\u52a0\u9501\u533a\u57df&#xff09;<\/p>\n<ul>\n<li>\u5f53\u63a5\u6536\u5230 \u201cHELLO\u201d \u6d88\u606f\u4e14 clientCount &lt; 2 \u65f6&#xff0c;\u5c06\u5f53\u524d\u5ba2\u6237\u7aef\u5730\u5740\u4fdd\u5b58\u5230 clientAddrs \u6570\u7ec4\u4e2d&#xff0c;\u540c\u65f6\u53d1\u9001 \u201cACK\u201d \u6d88\u606f\u786e\u8ba4\u6ce8\u518c\u3002<\/li>\n<li>\u8fd9\u4e00\u6b65\u786e\u4fdd\u670d\u52a1\u5668\u80fd\u8bb0\u5f55\u6bcf\u4e2a\u5ba2\u6237\u7aef NAT \u6620\u5c04\u540e\u7684\u516c\u7f51\u5730\u5740\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5730\u5740\u4e92\u6362\u4e0e\u63a2\u6d4b&#xff08;\u5f53\u4e24\u4e2a\u5ba2\u6237\u7aef\u5747\u5df2\u6ce8\u518c\u65f6&#xff09;<\/p>\n<ul>\n<li>\u5982\u679c clientCount &#061;&#061; 2&#xff0c;\u670d\u52a1\u5668\u6784\u9020\u4e24\u4e2a\u5b57\u7b26\u4e32&#xff1a;\n<ul>\n<li>\u5206\u522b\u5305\u542b\u5bf9\u65b9\u7684\u516c\u7f51 IP \u548c\u6620\u5c04\u540e\u7684\u7aef\u53e3&#xff0c;\u683c\u5f0f\u4e3a &#034;PEER &lt;ip&gt; &lt;port&gt;&#034;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u5206\u522b\u5c06\u8be5\u4fe1\u606f\u53d1\u9001\u7ed9\u4e24\u4e2a\u5ba2\u6237\u7aef&#xff0c;\u5b8c\u6210\u5730\u5740\u4fe1\u606f\u7684\u4e92\u6362\u3002<\/li>\n<li>\u989d\u5916\u53d1\u9001\u201cping\u201d\u6570\u636e\u5305\u7ed9\u53cc\u65b9&#xff0c;\u4ee5\u786e\u4fdd\u53cc\u65b9 NAT \u6620\u5c04\u4e0d\u4f1a\u56e0\u957f\u65f6\u95f4\u65e0\u6570\u636e\u800c\u5173\u95ed\u3002<\/li>\n<li>\u6700\u540e\u91cd\u7f6e clientCount&#xff0c;\u7b49\u5f85\u4e0b\u4e00\u7ec4\u5ba2\u6237\u7aef\u6ce8\u518c\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u9000\u51fa\u4e0e\u5173\u95ed\u5957\u63a5\u5b57<\/p>\n<ul>\n<li>\u5faa\u73af\u7ed3\u675f\u540e\u5173\u95ed\u5957\u63a5\u5b57\u5e76\u8fd4\u56de\u3002<\/li>\n<\/ul>\n<\/li>\n<h4>client.cpp(\u53cc\u65b9\u4e00\u81f4)<\/h4>\n<p><span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;iostream&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;cstring&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;unistd.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;arpa\/inet.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;errno.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;pthread.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;stdlib.h&gt;<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">include<\/span> <span class=\"token string\">&lt;net\/if.h&gt;<\/span>  <span class=\"token comment\">\/\/ \u7528\u4e8e IFNAMSIZ \u548c if_nametoindex<\/span><\/span><\/p>\n<p><span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">define<\/span> <span class=\"token macro-name\">SERVER_PORT<\/span> <span class=\"token expression\"><span class=\"token number\">50001<\/span>        <\/span><span class=\"token comment\">\/\/ \u670d\u52a1\u5668\u7aef\u53e3\u53f7<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">define<\/span> <span class=\"token macro-name\">BUF_SIZE<\/span> <span class=\"token expression\"><span class=\"token number\">1024<\/span>            <\/span><span class=\"token comment\">\/\/ \u7f13\u51b2\u533a\u5927\u5c0f<\/span><\/span><br \/>\n<span class=\"token macro property\"><span class=\"token directive-hash\">#<\/span><span class=\"token directive keyword\">define<\/span> <span class=\"token macro-name\">KEEP_ALIVE_INTERVAL<\/span> <span class=\"token expression\"><span class=\"token number\">25<\/span>   <\/span><span class=\"token comment\">\/\/ \u4fdd\u6d3b\u5305\u53d1\u9001\u95f4\u9694&#xff08;\u79d2&#xff09;<\/span><\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u5168\u5c40\u53d8\u91cf&#xff1a;\u4fdd\u5b58\u5bf9\u7b49\u7aef&#xff08;peer&#xff09;\u7684\u5730\u5740\u4fe1\u606f<\/span><br \/>\n<span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> peerAddr<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u5168\u5c40\u7684 UDP \u5957\u63a5\u5b57\u63cf\u8ff0\u7b26&#xff08;\u7528\u4e8e\u6240\u6709\u64cd\u4f5c&#xff09;<\/span><br \/>\n<span class=\"token keyword\">int<\/span> sockfd<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u5b9a\u4e49\u4e92\u65a5\u9501&#xff0c;\u7528\u4e8e\u4fdd\u62a4\u5171\u4eab\u7684\u5957\u63a5\u5b57\u64cd\u4f5c&#xff0c;\u907f\u514d\u591a\u7ebf\u7a0b\u7ade\u4e89<\/span><br \/>\npthread_mutex_t sock_mutex <span class=\"token operator\">&#061;<\/span> PTHREAD_MUTEX_INITIALIZER<span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u4fdd\u6d3b\u7ebf\u7a0b\u51fd\u6570&#xff1a;\u5b9a\u65f6\u5411\u5bf9\u65b9\u53d1\u9001 &#034;KEEP_ALIVE&#034; \u6d88\u606f&#xff0c;\u4fdd\u6301 NAT \u6620\u5c04<\/span><br \/>\n<span class=\"token keyword\">void<\/span><span class=\"token operator\">*<\/span> <span class=\"token function\">keep_alive<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">void<\/span><span class=\"token operator\">*<\/span> arg<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> keepAliveMsg <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#034;KEEP_ALIVE&#034;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token boolean\">true<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_lock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>sock_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u4f7f\u7528 sendto() \u53d1\u9001\u4fdd\u6d3b\u5305\u5230\u5bf9\u65b9\u5730\u5740<\/span><br \/>\n        <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> keepAliveMsg<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>keepAliveMsg<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n            <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>peerAddr<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>peerAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_unlock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>sock_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;[KeepAlive] Sent keep alive to peer.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">sleep<\/span><span class=\"token punctuation\">(<\/span>KEEP_ALIVE_INTERVAL<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token keyword\">int<\/span> <span class=\"token function\">main<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> argc<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> argv<span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token comment\">\/\/ \u547d\u4ee4\u884c\u53c2\u6570&#xff1a;\u9700\u8981\u4f20\u5165\u670d\u52a1\u5668 IP \u548c\u672c\u5730\u7ed1\u5b9a\u7684\u7f51\u7edc\u63a5\u53e3&#xff08;\u4f8b\u5982 &#034;eth0&#034;&#xff09;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>argc <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Usage: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> argv<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034; &lt;server_ip&gt; &lt;bind_interface&gt;&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Example: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> argv<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034; 203.0.113.5 eth0&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> serverIP <span class=\"token operator\">&#061;<\/span> argv<span class=\"token punctuation\">[<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> bindInterface <span class=\"token operator\">&#061;<\/span> argv<span class=\"token punctuation\">[<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u6307\u5b9a\u7ed1\u5b9a\u7684\u7f51\u7edc\u63a5\u53e3<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 1. \u521b\u5efa UDP \u5957\u63a5\u5b57<\/span><br \/>\n    sockfd <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">socket<\/span><span class=\"token punctuation\">(<\/span>AF_INET<span class=\"token punctuation\">,<\/span> SOCK_DGRAM<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>sockfd <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: Socket creation error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 2. \u7ed1\u5b9a\u5957\u63a5\u5b57\u5230\u6307\u5b9a\u7f51\u7edc\u63a5\u53e3<\/span><br \/>\n    <span class=\"token comment\">\/\/ \u8fd9\u4e00\u6b65\u53ef\u4ee5\u786e\u4fdd\u6570\u636e\u5305\u901a\u8fc7\u6307\u5b9a\u7684\u63a5\u53e3\u53d1\u9001&#xff0c;\u9632\u6b62\u201cNetwork is unreachable\u201d\u9519\u8bef<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">setsockopt<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> SOL_SOCKET<span class=\"token punctuation\">,<\/span> SO_BINDTODEVICE<span class=\"token punctuation\">,<\/span> bindInterface<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>bindInterface<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: SO_BINDTODEVICE error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 3. \u7ed1\u5b9a\u672c\u5730\u5730\u5740&#xff0c;\u8ba9\u7cfb\u7edf\u81ea\u52a8\u5206\u914d\u7aef\u53e3&#xff08;\u65e0\u9700\u56fa\u5b9a\u7aef\u53e3&#xff09;<\/span><br \/>\n    <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> localAddr<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>localAddr<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>localAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    localAddr<span class=\"token punctuation\">.<\/span>sin_family <span class=\"token operator\">&#061;<\/span> AF_INET<span class=\"token punctuation\">;<\/span><br \/>\n    localAddr<span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">.<\/span>s_addr <span class=\"token operator\">&#061;<\/span> INADDR_ANY<span class=\"token punctuation\">;<\/span><br \/>\n    localAddr<span class=\"token punctuation\">.<\/span>sin_port <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">htons<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ 0 \u8868\u793a\u7531\u7cfb\u7edf\u81ea\u52a8\u5206\u914d<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">bind<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>localAddr<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>localAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: Bind error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 4. \u8bbe\u7f6e\u670d\u52a1\u5668\u5730\u5740\u7ed3\u6784<\/span><br \/>\n    <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> serverAddr<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>serverAddr<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>serverAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    serverAddr<span class=\"token punctuation\">.<\/span>sin_family <span class=\"token operator\">&#061;<\/span> AF_INET<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token comment\">\/\/ \u5c06\u670d\u52a1\u5668 IP \u8f6c\u6362\u4e3a\u7f51\u7edc\u5730\u5740\u683c\u5f0f<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">inet_pton<\/span><span class=\"token punctuation\">(<\/span>AF_INET<span class=\"token punctuation\">,<\/span> serverIP<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>serverAddr<span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: Invalid server IP.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    serverAddr<span class=\"token punctuation\">.<\/span>sin_port <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">htons<\/span><span class=\"token punctuation\">(<\/span>SERVER_PORT<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    socklen_t serverLen <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>serverAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 5. \u5411\u670d\u52a1\u5668\u53d1\u9001\u6ce8\u518c\u6d88\u606f &#034;HELLO&#034;<\/span><br \/>\n    <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> helloMsg <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#034;HELLO&#034;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> helloMsg<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>helloMsg<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n        <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>serverAddr<span class=\"token punctuation\">,<\/span> serverLen<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: sendto error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Sent HELLO to server.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 6. \u63a5\u6536\u6765\u81ea\u670d\u52a1\u5668\u7684\u56de\u590d<\/span><br \/>\n    <span class=\"token keyword\">char<\/span> buffer<span class=\"token punctuation\">[<\/span>BUF_SIZE<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">{<\/span> <span class=\"token number\">0<\/span> <span class=\"token punctuation\">}<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr_in<\/span> fromAddr<span class=\"token punctuation\">;<\/span><br \/>\n    socklen_t fromLen <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>fromAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">int<\/span> n <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">recvfrom<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> buffer<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>fromAddr<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>fromLen<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: recvfrom error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    buffer<span class=\"token punctuation\">[<\/span>n<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token char\">&#039;\\\\0&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Received from server: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> buffer <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 7. \u5982\u679c\u6536\u5230\u7684\u662f ACK&#xff0c;\u5219\u7ee7\u7eed\u7b49\u5f85\u670d\u52a1\u5668\u53d1\u6765\u7684 PEER \u4fe1\u606f<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">strncmp<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;ACK&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">recvfrom<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> buffer<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>fromAddr<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>fromLen<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: recvfrom error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        buffer<span class=\"token punctuation\">[<\/span>n<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token char\">&#039;\\\\0&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Received from server: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> buffer <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 8. \u89e3\u6790\u670d\u52a1\u5668\u8fd4\u56de\u7684 PEER \u4fe1\u606f&#xff0c;\u683c\u5f0f\u4e3a &#034;PEER &lt;peer_ip&gt; &lt;peer_port&gt;&#034;<\/span><br \/>\n    <span class=\"token keyword\">char<\/span> peerIP<span class=\"token punctuation\">[<\/span>INET_ADDRSTRLEN<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">int<\/span> peerPort<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">sscanf<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;PEER %s %d&#034;<\/span><span class=\"token punctuation\">,<\/span> peerIP<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>peerPort<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>peerAddr<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>peerAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        peerAddr<span class=\"token punctuation\">.<\/span>sin_family <span class=\"token operator\">&#061;<\/span> AF_INET<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">inet_pton<\/span><span class=\"token punctuation\">(<\/span>AF_INET<span class=\"token punctuation\">,<\/span> peerIP<span class=\"token punctuation\">,<\/span> <span class=\"token operator\">&amp;<\/span>peerAddr<span class=\"token punctuation\">.<\/span>sin_addr<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: Invalid peer IP.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        peerAddr<span class=\"token punctuation\">.<\/span>sin_port <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">htons<\/span><span class=\"token punctuation\">(<\/span>peerPort<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Peer address: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> peerIP <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;:&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> peerPort <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token keyword\">else<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: Failed to parse peer info.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 9. \u5728\u6536\u5230 PEER \u4fe1\u606f\u540e&#xff0c;\u5ba2\u6237\u7aef\u53ef\u4ee5\u7acb\u5373\u5411\u5bf9\u65b9\u53d1\u9001\u201c\u6572\u95e8\u201d\u5305&#xff0c;\u4ee5\u89e6\u53d1 NAT \u6620\u5c04<\/span><br \/>\n    <span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span> knockMsg <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#034;knock&#034;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> knockMsg<span class=\"token punctuation\">,<\/span> <span class=\"token function\">strlen<\/span><span class=\"token punctuation\">(<\/span>knockMsg<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n        <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>peerAddr<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>peerAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Sent knock to peer.&#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 10. \u542f\u52a8\u4fdd\u6d3b\u7ebf\u7a0b&#xff0c;\u5b9a\u65f6\u5411\u5bf9\u65b9\u53d1\u9001 &#034;KEEP_ALIVE&#034; \u5305&#xff0c;\u4fdd\u6301 NAT \u6620\u5c04<\/span><br \/>\n    pthread_t kaThread<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token function\">pthread_create<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>kaThread<span class=\"token punctuation\">,<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">,<\/span> keep_alive<span class=\"token punctuation\">,<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">!&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cerr <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Client: pthread_create error: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token function\">strerror<\/span><span class=\"token punctuation\">(<\/span>errno<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ 11. P2P \u4ea4\u4e92&#xff1a;\u4ece\u6807\u51c6\u8f93\u5165\u8bfb\u53d6\u6d88\u606f&#xff0c;\u5411\u5bf9\u65b9\u53d1\u9001&#xff0c;\u5e76\u63a5\u6536\u5bf9\u65b9\u56de\u590d<\/span><br \/>\n    <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token boolean\">true<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Enter message to send to peer: &#034;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span>string input<span class=\"token punctuation\">;<\/span><br \/>\n        std<span class=\"token double-colon punctuation\">::<\/span><span class=\"token function\">getline<\/span><span class=\"token punctuation\">(<\/span>std<span class=\"token double-colon punctuation\">::<\/span>cin<span class=\"token punctuation\">,<\/span> input<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>input<span class=\"token punctuation\">.<\/span><span class=\"token function\">empty<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">continue<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u52a0\u9501\u786e\u4fdd\u53d1\u9001\u6570\u636e\u65f6\u5957\u63a5\u5b57\u64cd\u4f5c\u4e0d\u4f1a\u4e0e\u4fdd\u6d3b\u7ebf\u7a0b\u51b2\u7a81<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_lock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>sock_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">sendto<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> input<span class=\"token punctuation\">.<\/span><span class=\"token function\">c_str<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> input<span class=\"token punctuation\">.<\/span><span class=\"token function\">length<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span><br \/>\n            <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">sockaddr<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>peerAddr<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>peerAddr<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">pthread_mutex_unlock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">&amp;<\/span>sock_mutex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u8bbe\u7f6e\u63a5\u6536\u8d85\u65f6&#xff0c;\u7b49\u5f85\u5bf9\u65b9\u56de\u590d<\/span><br \/>\n        <span class=\"token function\">memset<\/span><span class=\"token punctuation\">(<\/span>buffer<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">struct<\/span> <span class=\"token class-name\">timeval<\/span> tv<span class=\"token punctuation\">;<\/span><br \/>\n        tv<span class=\"token punctuation\">.<\/span>tv_sec <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">5<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        tv<span class=\"token punctuation\">.<\/span>tv_usec <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token function\">setsockopt<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> SOL_SOCKET<span class=\"token punctuation\">,<\/span> SO_RCVTIMEO<span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">const<\/span> <span class=\"token keyword\">char<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token operator\">&amp;<\/span>tv<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">sizeof<\/span><span class=\"token punctuation\">(<\/span>tv<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">recvfrom<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">,<\/span> buffer<span class=\"token punctuation\">,<\/span> BUF_SIZE<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token constant\">NULL<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&gt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            buffer<span class=\"token punctuation\">[<\/span>n<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token char\">&#039;\\\\0&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            std<span class=\"token double-colon punctuation\">::<\/span>cout <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token string\">&#034;Received from peer: &#034;<\/span> <span class=\"token operator\">&lt;&lt;<\/span> buffer <span class=\"token operator\">&lt;&lt;<\/span> std<span class=\"token double-colon punctuation\">::<\/span>endl<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token function\">close<\/span><span class=\"token punctuation\">(<\/span>sockfd<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<hr \/>\n<li>\n<p>\u5934\u6587\u4ef6\u5305\u542b\u4e0e\u5b8f\u5b9a\u4e49<\/p>\n<ul>\n<li>\u5305\u542b\u4e86\u8fdb\u884c\u7f51\u7edc\u7f16\u7a0b\u3001\u7ebf\u7a0b\u540c\u6b65\u3001\u5b57\u7b26\u4e32\u5904\u7406\u3001\u9519\u8bef\u5904\u7406\u7b49\u6240\u9700\u7684\u5934\u6587\u4ef6\u3002<\/li>\n<li>\u5b9a\u4e49\u670d\u52a1\u5668\u7aef\u53e3\u53f7\u3001\u7f13\u51b2\u533a\u5927\u5c0f\u548c\u4fdd\u6d3b\u5305\u7684\u53d1\u9001\u95f4\u9694\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5168\u5c40\u53d8\u91cf<\/p>\n<ul>\n<li>peerAddr&#xff1a;\u7528\u4e8e\u4fdd\u5b58\u5bf9\u65b9\u5ba2\u6237\u7aef\u7684\u516c\u7f51\u6620\u5c04\u5730\u5740\u3002<\/li>\n<li>sockfd&#xff1a;\u5168\u5c40 UDP \u5957\u63a5\u5b57&#xff0c;\u7528\u4e8e\u6240\u6709\u6570\u636e\u4f20\u8f93\u3002<\/li>\n<li>sock_mutex&#xff1a;\u4e92\u65a5\u9501&#xff0c;\u786e\u4fdd\u591a\u7ebf\u7a0b&#xff08;\u4fdd\u6d3b\u7ebf\u7a0b\u4e0e\u4e3b\u7ebf\u7a0b&#xff09;\u5bf9\u540c\u4e00\u5957\u63a5\u5b57\u7684\u64cd\u4f5c\u4e0d\u4f1a\u51b2\u7a81\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>keep_alive() \u4fdd\u6d3b\u7ebf\u7a0b<\/p>\n<ul>\n<li>\u5faa\u73af\u5185\u4f7f\u7528\u4e92\u65a5\u9501\u4fdd\u62a4\u5bf9 sockfd \u7684 sendto \u64cd\u4f5c&#xff0c;\u5411 peerAddr \u53d1\u9001 \u201cKEEP_ALIVE\u201d \u6d88\u606f&#xff0c;\u95f4\u9694 25 \u79d2\u4e00\u6b21&#xff0c;\u5e2e\u52a9\u4fdd\u6301 NAT \u6620\u5c04\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>main() \u51fd\u6570\u5f00\u59cb<\/p>\n<ul>\n<li>\u68c0\u67e5\u547d\u4ee4\u884c\u53c2\u6570&#xff0c;\u8981\u6c42\u4f20\u5165\u670d\u52a1\u5668 IP \u548c\u672c\u5730\u7ed1\u5b9a\u7684\u7f51\u7edc\u63a5\u53e3&#xff08;\u4f8b\u5982 \u201ceth0\u201d&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u521b\u5efa UDP \u5957\u63a5\u5b57<\/p>\n<ul>\n<li>\u4f7f\u7528 socket() \u521b\u5efa\u4e00\u4e2a UDP \u5957\u63a5\u5b57&#xff0c;\u5e76\u68c0\u67e5\u662f\u5426\u6210\u529f\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u7ed1\u5b9a\u7f51\u7edc\u63a5\u53e3<\/p>\n<ul>\n<li>\u901a\u8fc7 setsockopt() \u4f7f\u7528 SO_BINDTODEVICE \u5c06\u5957\u63a5\u5b57\u7ed1\u5b9a\u5230\u6307\u5b9a\u7f51\u7edc\u63a5\u53e3&#xff0c;\u786e\u4fdd\u6570\u636e\u5305\u8d70\u6b63\u786e\u7684\u7f51\u7edc\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u7ed1\u5b9a\u672c\u5730\u5730\u5740<\/p>\n<ul>\n<li>\u7ed1\u5b9a\u672c\u5730\u5730\u5740&#xff0c;\u8ba9\u7cfb\u7edf\u81ea\u52a8\u5206\u914d\u7aef\u53e3&#xff08;\u4f7f\u7528\u7aef\u53e3 0&#xff09;\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u8bbe\u7f6e\u670d\u52a1\u5668\u5730\u5740<\/p>\n<ul>\n<li>\u6784\u9020\u670d\u52a1\u5668\u5730\u5740\u7ed3\u6784\u4f53&#xff0c;\u8f6c\u6362\u670d\u52a1\u5668 IP \u5b57\u7b26\u4e32\u4e3a\u7f51\u7edc\u683c\u5f0f&#xff0c;\u5e76\u8bbe\u7f6e\u670d\u52a1\u5668\u7aef\u53e3\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5411\u670d\u52a1\u5668\u53d1\u9001\u6ce8\u518c\u6d88\u606f \u201cHELLO\u201d<\/p>\n<ul>\n<li>\u4f7f\u7528 sendto() \u53d1\u9001 \u201cHELLO\u201d \u6d88\u606f\u7ed9\u670d\u52a1\u5668&#xff0c;\u901a\u77e5\u670d\u52a1\u5668\u672c\u5ba2\u6237\u7aef\u6ce8\u518c\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u63a5\u6536\u670d\u52a1\u5668\u56de\u590d<\/p>\n<ul>\n<li>\u8c03\u7528 recvfrom() \u63a5\u6536\u670d\u52a1\u5668\u7684\u56de\u5e94\u3002<\/li>\n<li>\u7b2c\u4e00\u6b21\u53ef\u80fd\u6536\u5230 ACK&#xff0c;\u5982\u679c\u6536\u5230 ACK&#xff0c;\u5219\u7ee7\u7eed\u7b49\u5f85\u670d\u52a1\u5668\u53d1\u9001\u5305\u542b\u5bf9\u65b9\u5730\u5740\u7684 PEER \u4fe1\u606f\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u89e3\u6790 PEER \u4fe1\u606f<\/p>\n<ul>\n<li>\u4f7f\u7528 sscanf() \u89e3\u6790\u670d\u52a1\u5668\u8fd4\u56de\u7684\u5b57\u7b26\u4e32&#xff0c;\u63d0\u53d6\u51fa\u5bf9\u65b9\u7684\u516c\u7f51 IP \u548c\u6620\u5c04\u7aef\u53e3&#xff0c;\u5e76\u5b58\u5165 peerAddr \u7ed3\u6784\u4f53\u4e2d\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u4e3b\u52a8\u5411\u5bf9\u65b9\u53d1\u9001\u201c\u6572\u95e8\u201d\u5305<\/p>\n<ul>\n<li>\u6536\u5230\u5bf9\u65b9\u5730\u5740\u540e&#xff0c;\u7acb\u5373\u4f7f\u7528 sendto() \u5411\u8be5\u5730\u5740\u53d1\u9001 \u201cknock\u201d \u5305&#xff0c;\u4ee5\u89e6\u53d1 NAT \u6620\u5c04\u7684\u5efa\u7acb\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u542f\u52a8\u4fdd\u6d3b\u7ebf\u7a0b<\/p>\n<ul>\n<li>\u521b\u5efa\u4e00\u4e2a\u65b0\u7ebf\u7a0b\u8fd0\u884c keep_alive()&#xff0c;\u5b9a\u65f6\u5411\u5bf9\u65b9\u53d1\u9001\u4fdd\u6d3b\u5305&#xff0c;\u9632\u6b62 NAT \u6620\u5c04\u8d85\u65f6\u5173\u95ed\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u8fdb\u5165 P2P \u4ea4\u4e92\u5faa\u73af<\/p>\n<ul>\n<li>\u5faa\u73af\u4e2d\u63d0\u793a\u7528\u6237\u8f93\u5165\u6d88\u606f&#xff0c;\u7136\u540e\u52a0\u9501\u901a\u8fc7 sendto() \u53d1\u9001\u7ed9\u5bf9\u65b9\u3002<\/li>\n<li>\u8bbe\u7f6e\u63a5\u6536\u8d85\u65f6&#xff0c;\u4f7f\u7528 recvfrom() \u5c1d\u8bd5\u63a5\u6536\u5bf9\u65b9\u7684\u56de\u590d&#xff0c;\u5e76\u6253\u5370\u6536\u5230\u7684\u6570\u636e\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5173\u95ed\u5957\u63a5\u5b57\u5e76\u7ed3\u675f\u7a0b\u5e8f<\/p>\n<ul>\n<li>\u5faa\u73af\u9000\u51fa\u540e\u5173\u95ed\u5957\u63a5\u5b57\u3002<\/li>\n<\/ul>\n<\/li>\n","protected":false},"excerpt":{"rendered":"<p>\u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb1.3k\u6b21\uff0c\u70b9\u8d5e51\u6b21\uff0c\u6536\u85cf10\u6b21\u3002\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e\u2013\uff1e\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1\uff08\u6210\u529f\u7248\uff09\u6839\u636e\u4e0a\u4e2a\u6587\u7ae0\u7684\u5206\u6790 \u95ee\u9898\u53ef\u80fd\u51fa\u73b0\u5728\u4e0a\u9762 \u6211\u8fd9\u91cc\u91cd\u65b0\u67e5\u627e\u8d44\u6599\u6000\u7591\uff1a1 NAT\u6620\u5c04\u53ef\u80fd\u30022 NAT\u6620\u5c04\u4fdd\u5b58\uff0c\u5e76\u4e14 NAT \u53ef\u80fd\u4f1a\u5728\u77ed\u65f6\u95f4\u5185\uff0c\u9700\u8981\u4e00\u76f4\u4fdd\u6301\u6620\u5c04\u3002\u6709\u4e9b NAT \u8bbe\u5907\u4f1a\u56e0\u4e3a\u77ed\u65f6\u95f4\u5185\u6ca1\u6709\u6570\u636e\u800c\u56de\u6536\u7aef\u53e3\u6620\u5c04\uff0c\u5bfc\u81f4\u670d\u52a1\u5668\u63d0\u4f9b\u7684 IP:Port \u5931\u6548\u3002\uff1a\u53cc\u65b9\u5b9a\u671f\u53d1\u9001\u4fdd\u6d3b\u5305\u4ee5\u9632 NAT \u8d85\u65f6\u5173\u95ed\u6620\u5c04\u30023 \u670d\u52a1\u5668\u53ea\u662f\u5411\u53cc\u65b9\u53d1\u9001\u4e86IP\u548c\u7aef\u53e3\u540e\u76f4\u63a5\u9000\u51fa\u4e86\uff0c\u5e76\u672a\u53d1\u9001\u6570\u636e\u5305\u7ed9\u5ba2\u6237\u7aef\uff0c\u5bfc\u81f4\u3002_linuz udp \u6253\u6d1e<\/p>\n","protected":false},"author":2,"featured_media":17266,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[58,43,78],"topic":[],"class_list":["post-17267","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-linux","tag-43","tag-78"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v20.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e-\uff1e\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1\uff08\u6210\u529f\u7248\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/17267.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e-\uff1e\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1\uff08\u6210\u529f\u7248\uff09 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"\u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb1.3k\u6b21\uff0c\u70b9\u8d5e51\u6b21\uff0c\u6536\u85cf10\u6b21\u3002\u3010Linux\u3011\u3010\u7f51\u7edc\u3011UDP\u6253\u6d1e\u2013\uff1e\u4e0d\u540c\u5b50\u7f51\u4e0b\u7684\u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u901a\u4fe1\uff08\u6210\u529f\u7248\uff09\u6839\u636e\u4e0a\u4e2a\u6587\u7ae0\u7684\u5206\u6790 \u95ee\u9898\u53ef\u80fd\u51fa\u73b0\u5728\u4e0a\u9762 \u6211\u8fd9\u91cc\u91cd\u65b0\u67e5\u627e\u8d44\u6599\u6000\u7591\uff1a1 NAT\u6620\u5c04\u53ef\u80fd\u30022 NAT\u6620\u5c04\u4fdd\u5b58\uff0c\u5e76\u4e14 NAT \u53ef\u80fd\u4f1a\u5728\u77ed\u65f6\u95f4\u5185\uff0c\u9700\u8981\u4e00\u76f4\u4fdd\u6301\u6620\u5c04\u3002\u6709\u4e9b NAT \u8bbe\u5907\u4f1a\u56e0\u4e3a\u77ed\u65f6\u95f4\u5185\u6ca1\u6709\u6570\u636e\u800c\u56de\u6536\u7aef\u53e3\u6620\u5c04\uff0c\u5bfc\u81f4\u670d\u52a1\u5668\u63d0\u4f9b\u7684 IP:Port \u5931\u6548\u3002\uff1a\u53cc\u65b9\u5b9a\u671f\u53d1\u9001\u4fdd\u6d3b\u5305\u4ee5\u9632 NAT \u8d85\u65f6\u5173\u95ed\u6620\u5c04\u30023 \u670d\u52a1\u5668\u53ea\u662f\u5411\u53cc\u65b9\u53d1\u9001\u4e86IP\u548c\u7aef\u53e3\u540e\u76f4\u63a5\u9000\u51fa\u4e86\uff0c\u5e76\u672a\u53d1\u9001\u6570\u636e\u5305\u7ed9\u5ba2\u6237\u7aef\uff0c\u5bfc\u81f4\u3002_linuz udp \u6253\u6d1e\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/17267.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2025-04-18T15:42:31+00:00\" \/>\n<meta property=\"og:image\" 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