{"id":116740,"date":"2026-10-22T01:49:51","date_gmt":"2026-10-21T17:49:51","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/116740.html"},"modified":"2026-10-22T01:49:51","modified_gmt":"2026-10-21T17:49:51","slug":"%e3%80%90linux-%e7%bd%91%e7%bb%9c%e7%bc%96%e7%a8%8b%e3%80%91udp-socket-%e7%bc%96%e7%a8%8b%ef%bc%88%e4%b8%8a%ef%bc%89%ef%bc%9a%e4%bb%8e%e5%9c%b0%e5%9d%80%e4%b8%8e%e5%ad%97%e8%8a%82%e5%ba%8f%e5%88%b0","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/116740.html","title":{"rendered":"\u3010Linux \u7f51\u7edc\u7f16\u7a0b\u3011UDP Socket \u7f16\u7a0b\uff08\u4e0a\uff09\uff1a\u4ece\u5730\u5740\u4e0e\u5b57\u8282\u5e8f\u5230\u5b8c\u6574\u56de\u663e\u670d\u52a1\u5668"},"content":{"rendered":"

\/* MD \/ \u5bcc\u6587\u672c\u4e2d\u7684 .toc\uff08\u542b\u535a\u5ba2\u56ed\u642c\u5bb6\u7b49\u5d4c\u5957\u7ed3\u6784\uff09\uff1b.toc-box \u5728\u4fa7\u680f\uff0c\u4e0d\u53d7\u5f71\u54cd *\/
\n #content_views .toc,
\n \/* \u7f16\u8f91\u5668\u5e38\u5728\u76ee\u5f55\u524d\u540e\u63d2\u5165\u7a7a p\uff08:empty \u4ecd\u5360 20px\uff09\uff0c\u4e00\u5e76\u53bb\u6389\u907f\u514d\u9876\u7a7a\u9699 *\/
\n #content_views.markdown_views > p:empty:has(+ .toc),
\n #content_views.markdown_views > .toc + p:empty,
\n \/* \u5bcc\u6587\u672c\u65e7\u7248\u76ee\u5f55\u6807\u8bb0 *\/
\n #content_views.htmledit_views #main-toc,
\n #content_views.htmledit_views #hr-toc,
\n #content_views.htmledit_views p[id*=\\”-toc\\”] {
\n display: none !important;
\n }
\n \/* \u76ee\u5f55\u53bb\u6389\u540e\uff0c\u7d27\u8ddf\u7684\u9996\u4e2a\u6807\u9898\u4e0d\u518d\u591a\u51fa\u4e00\u5757\u4e0a\u8fb9\u8ddd *\/
\n #content_views.markdown_views > .toc + h1,
\n #content_views.markdown_views > .toc + h2,
\n #content_views.markdown_views > .toc + h3,
\n #content_views.markdown_views > .toc + h4,
\n #content_views.markdown_views > .toc + p:empty + h1,
\n #content_views.markdown_views > .toc + p:empty + h2,
\n #content_views.markdown_views > .toc + p:empty + h3,
\n #content_views.markdown_views > .toc + p:empty + h4 {
\n margin-top: 0 !important;
\n }<\/p>\n

🔥 \u661f\u5149\u7f16\u8bd1\u8005<\/b><\/font> \u00b7 \u4e2a\u4eba\u4e3b\u9875<\/p>\n

📚 \u5b66\u4e60\u4e13\u680f：<\/b><\/font> \u300aC\/C++ \u6210\u957f\u7b14\u8bb0\u300b<\/font> \u00b7 \u300aLinux \u5b9e\u8df5\u624b\u518c\u300b<\/font> \u00b7 \u300a\u6570\u636e\u7ed3\u6784\u4e0e\u7b97\u6cd5\u300b<\/font><\/p>\n

🌄 \u5411\u4e91\u7aef\u98de\u626c，\u7f16\u8bd1\u5c5e\u4e8e\u81ea\u5df1\u7684\u4ee3\u7801\u661f\u6cb3\u3002<\/b><\/font><\/p>\n

\n

\u2615 \u5199\u5728\u5f00\u7bc7<\/font><\/h4>\n

\u2003\u2003\u4f60\u597d，\u8fd9\u91cc\u662f \u661f\u5149\u7f16\u8bd1\u8005<\/b><\/font>\u3002<\/font><\/p>\n

\u2003\u2003\u8fd9\u91cc\u8bb0\u5f55\u6211\u5728 C\/C++\u3001Linux\u3001\u6570\u636e\u7ed3\u6784\u4e0e\u7b97\u6cd5<\/b><\/font> \u5b66\u4e60\u4e2d\u9047\u5230\u7684\u771f\u5b9e\u95ee\u9898\u3001\u4eb2\u624b\u9a8c\u8bc1\u8fc7\u7684\u4ee3\u7801，\u4ee5\u53ca\u90a3\u4e9b\u5bb9\u6613\u88ab\u5ffd\u7565\u7684\u5b9e\u73b0\u7ec6\u8282\u3002<\/font><\/p>\n

\u2003\u2003\u6bd4\u8d77\u7b80\u5355\u7f57\u5217\u7ed3\u8bba，\u6211\u66f4\u613f\u610f\u4ece\u95ee\u9898\u51fa\u53d1，\u628a\u4e00\u4e2a\u77e5\u8bc6\u70b9\u7684\u6765\u7531\u8bb2\u6e05\u695a，\u628a\u201c\u4e3a\u4ec0\u4e48\u4f1a\u8fd9\u6837<\/b><\/font>\u201d\u548c\u201c\u5e94\u8be5\u600e\u6837\u89e3\u51b3<\/b><\/font>\u201d\u8bf4\u660e\u767d，\u8ba9\u6bcf\u4e00\u6b21\u8e29\u5751\u90fd\u6c89\u6dc0\u6210\u53ef\u4ee5\u590d\u7528\u7684\u7ecf\u9a8c\u3002<\/font><\/p>\n

\u2003\u2003\u5982\u679c\u8fd9\u7bc7\u8bb0\u5f55\u80fd\u5e2e\u4f60\u5c11\u7ed5\u4e00\u70b9\u8def<\/b><\/font>，\u6216\u8ba9\u67d0\u4e2a\u6a21\u7cca\u7684\u5730\u65b9\u5ffd\u7136\u53d8\u5f97\u6e05\u6670，\u90a3\u4e48\u8fd9\u6b21\u5206\u4eab\u4fbf\u6709\u4e86\u610f\u4e49\u3002\u613f\u6211\u4eec\u5728\u4e00\u6b21\u6b21\u9605\u8bfb\u3001\u7f16\u8bd1\u4e0e\u8c03\u8bd5\u4e2d\u7a33\u6b65\u5411\u524d，\u6162\u6162\u642d\u8d77\u5c5e\u4e8e\u81ea\u5df1\u7684\u6280\u672f\u4e16\u754c\u3002<\/font><\/p>\n

\"\u661f\u5149\u7f16\u8bd1\u8005\u535a\u5ba2\u5f00\u573a\u52a8\u753b\" <\/p>\n

\n

<\/h2>\n

🔥 \u672c\u6587\u5b9a\u4f4d：\u4ece\u201c\u4e00\u4e2a\u8fdb\u7a0b\u600e\u6837\u628a\u6d88\u606f\u53d1\u7ed9\u53e6\u4e00\u4e2a\u8fdb\u7a0b\u201d\u51fa\u53d1，\u4e32\u8d77 UDP Socket \u7684\u5730\u5740\u6a21\u578b\u3001\u6838\u5fc3\u63a5\u53e3\u548c\u56de\u663e\u901a\u4fe1\u6d41\u7a0b\u3002<\/p>\n

💡 \u5b66\u4e60\u76ee\u6807：\u7406\u89e3 socket \/ bind \/ sendto \/ recvfrom；\u533a\u5206\u672c\u5730\u5730\u5740\u4e0e\u76ee\u6807\u5730\u5740；\u638c\u63e1\u7f51\u7edc\u5b57\u8282\u5e8f\u4e0e\u5730\u5740\u8f6c\u6362；\u80fd\u72ec\u7acb\u642d\u5efa\u56de\u663e\u670d\u52a1\u5668\u548c\u5ba2\u6237\u7aef\u3002<\/p>\n

📌 \u5b9e\u73b0\u8303\u56f4：Linux\u3001IPv4\u3001C++17\u3001\u963b\u585e\u5f0f UDP\u3002\u4ee3\u7801\u4f7f\u7528\u5c11\u91cf\u5f02\u5e38\u5904\u7406\u548c RAII \u7ba1\u7406\u8d44\u6e90，\u91cd\u70b9\u4ecd\u662f Socket \u8c03\u7528\u672c\u8eab\u3002<\/p>\n

\u8bfe\u7a0b PDF \u4e00\u5171\u6709 29 \u9875，\u4f9d\u6b21\u5305\u542b\u56de\u663e\u670d\u52a1\u5668\u3001\u7f51\u7edc\u5b57\u5178\u3001\u7b80\u5355\u804a\u5929\u5ba4\u4ee5\u53ca\u8865\u5145\u63a5\u53e3\u8bf4\u660e\u3002\u4e3a\u4e86\u4fdd\u6301\u4e00\u7bc7\u6587\u7ae0\u7684\u9605\u8bfb\u8282\u594f，\u8fd9\u6b21\u62c6\u6210\u4e0a\u4e0b\u4e24\u7bc7：\u4e0a\u7bc7\u5148\u628a\u901a\u4fe1\u95ed\u73af\u8dd1\u901a，\u4e0b\u7bc7\u518d\u8ba8\u8bba\u4e1a\u52a1\u5c01\u88c5\u3001\u5b57\u5178\u4e0e\u804a\u5929\u5ba4\u3002<\/p>\n

\u7cfb\u5217\u8854\u63a5：\u4e0b\u7bc7：\u7f51\u7edc\u5b57\u5178\u3001\u804a\u5929\u5ba4\u4e0e\u591a\u7ebf\u7a0b\u6536\u53d1\u3002\u4e0a\u7bc7\u5bf9\u5e94 PDF \u7b2c 1～6 \u9875，\u5e76\u63d0\u524d\u6574\u5408\u7b2c 26～28 \u9875\u7684\u5730\u5740\u8f6c\u6362\u5185\u5bb9\u3002<\/p>\n

\n

\u6587\u7ae0\u76ee\u5f55<\/h3>\n
    \n
  • \u4e00\u3001\u4ece\u672c\u5730\u8fdb\u7a0b\u901a\u4fe1\u8d70\u5411\u7f51\u7edc\u901a\u4fe1<\/li>\n
  • \u4e8c\u3001Socket \u5230\u5e95\u662f\u4ec0\u4e48<\/li>\n
  • \u4e09\u3001\u5148\u770b\u61c2 UDP \u901a\u4fe1\u7684\u6574\u4f53\u6d41\u7a0b<\/li>\n
  • \u56db\u3001\u5730\u5740\u7ed3\u6784\u4e0e\u7f51\u7edc\u5b57\u8282\u5e8f<\/li>\n
  • \u4e94\u3001\u670d\u52a1\u5668\u4e3a\u4ec0\u4e48\u8981 bind<\/li>\n
  • \u516d\u3001sendto \u4e0e recvfrom \u7684\u53c2\u6570\u600e\u4e48\u8bfb<\/li>\n
  • \u4e03\u3001UDP \u7684\u6d88\u606f\u8fb9\u754c\u4e0e\u8fd4\u56de\u503c\u9677\u9631<\/li>\n
  • \u516b\u3001\u5b8c\u6574\u7684\u56de\u663e\u670d\u52a1\u5668\u4e0e\u5ba2\u6237\u7aef<\/li>\n
  • \u4e5d\u3001\u7f16\u8bd1\u8fd0\u884c\u4e0e\u9a8c\u8bc1\u65b9\u6cd5<\/li>\n
  • \u5341\u3001\u5e38\u89c1\u9519\u8bef\u4e0e\u6392\u67e5\u987a\u5e8f<\/li>\n
  • \u603b\u7ed3<\/li>\n<\/ul>\n
    \n

    \u4e00\u3001\u4ece\u672c\u5730\u8fdb\u7a0b\u901a\u4fe1\u8d70\u5411\u7f51\u7edc\u901a\u4fe1<\/h3>\n

    \u5b66\u8fc7\u7ba1\u9053\u3001\u5171\u4eab\u5185\u5b58\u548c\u6d88\u606f\u961f\u5217\u540e，\u6211\u4eec\u5df2\u7ecf\u77e5\u9053：\u4e24\u4e2a\u8fdb\u7a0b\u53ef\u4ee5\u901a\u8fc7\u64cd\u4f5c\u7cfb\u7edf\u63d0\u4f9b\u7684\u673a\u5236\u4ea4\u6362\u6570\u636e\u3002\u4f46\u8fd9\u4e9b\u673a\u5236\u901a\u5e38\u670d\u52a1\u4e8e\u540c\u4e00\u53f0\u673a\u5668\u4e0a\u7684\u8fdb\u7a0b\u3002<\/p>\n

    \u73b0\u5728\u628a\u95ee\u9898\u6269\u5927\u4e00\u70b9：\u5ba2\u6237\u7aef\u8fd0\u884c\u5728\u4e00\u53f0\u7535\u8111\u4e0a，\u670d\u52a1\u5668\u8fd0\u884c\u5728\u53e6\u4e00\u53f0 Linux \u4e3b\u673a\u4e0a\u3002\u4e24\u8005\u6ca1\u6709\u5171\u540c\u7684\u8fdb\u7a0b\u5730\u5740\u7a7a\u95f4，\u4e5f\u4e0d\u80fd\u76f4\u63a5\u5171\u4eab\u540c\u4e00\u4e2a\u666e\u901a\u7ba1\u9053\u3002\u6d88\u606f\u5fc5\u987b\u7ecf\u8fc7\u5404\u81ea\u7684\u64cd\u4f5c\u7cfb\u7edf\u548c\u7f51\u7edc\u8bbe\u5907，\u624d\u80fd\u5230\u8fbe\u53e6\u4e00\u53f0\u673a\u5668\u4e0a\u7684\u76ee\u6807\u8fdb\u7a0b\u3002<\/p>\n

    \u4e00\u6b21\u7f51\u7edc\u901a\u4fe1，\u81f3\u5c11\u8981\u89e3\u51b3\u4e09\u4e2a\u95ee\u9898：<\/p>\n

  • \u53bb\u54ea\u91cc：\u7528 IP \u5730\u5740\u63cf\u8ff0\u7f51\u7edc\u5c42\u9762\u7684\u76ee\u6807\u5730\u5740；<\/li>\n
  • \u4ea4\u7ed9\u54ea\u4e2a\u670d\u52a1：\u7528\u7aef\u53e3\u53f7\u53c2\u4e0e\u6807\u8bc6\u76ee\u6807\u901a\u4fe1\u7aef\u70b9；<\/li>\n
  • \u6309\u4ec0\u4e48\u65b9\u5f0f\u4ea4\u6362\u6570\u636e：\u9009\u62e9 UDP\u3001TCP \u7b49\u4f20\u8f93\u65b9\u5f0f\u3002<\/li>\n

    \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

    1.1 IP\u3001\u7aef\u53e3\u4e0e\u8fdb\u7a0b\u4e0d\u662f\u4e00\u4e00\u5bf9\u5e94<\/h4>\n

    \u5728\u5165\u95e8\u9636\u6bb5，\u53ef\u4ee5\u5148\u628a IP \u7406\u89e3\u4e3a\u201c\u627e\u5230\u76ee\u6807\u4e3b\u673a\u7684\u7ebf\u7d22\u201d，\u628a\u7aef\u53e3\u7406\u89e3\u4e3a\u201c\u627e\u5230\u76ee\u6807\u670d\u52a1\u5165\u53e3\u7684\u7ebf\u7d22\u201d\u3002\u4f46\u4e0d\u8981\u628a\u5b83\u4eec\u673a\u68b0\u5730\u7406\u89e3\u6210\u6c38\u4e45\u7684\u4e00\u4e00\u5bf9\u5e94\u5173\u7cfb\u3002<\/p>\n

    \u4e00\u53f0\u4e3b\u673a\u53ef\u80fd\u6709\u591a\u4e2a IP \u5730\u5740，\u4e00\u4e2a\u8fdb\u7a0b\u53ef\u4ee5\u62e5\u6709\u591a\u4e2a Socket\u3001\u7ed1\u5b9a\u591a\u4e2a\u7aef\u53e3；\u901a\u8fc7\u7aef\u53e3\u590d\u7528\u7b49\u673a\u5236，\u591a\u4e2a\u8fdb\u7a0b\u4e5f\u53ef\u80fd\u5171\u540c\u63d0\u4f9b\u4e00\u4e2a\u670d\u52a1\u3002\u64cd\u4f5c\u7cfb\u7edf\u5904\u7406\u6570\u636e\u65f6，\u8fd8\u9700\u8981\u7ed3\u5408\u534f\u8bae\u3001\u5730\u5740\u3001\u7aef\u53e3\u548c Socket \u72b6\u6001\u7b49\u4fe1\u606f\u3002<\/p>\n

    \u56e0\u6b64，\u6bd4\u201c\u7aef\u53e3\u5c31\u662f\u8fdb\u7a0b\u7f16\u53f7\u201d\u66f4\u51c6\u786e\u7684\u8bf4\u6cd5\u662f：\u7aef\u53e3\u53c2\u4e0e\u6807\u8bc6\u4f20\u8f93\u5c42\u901a\u4fe1\u7aef\u70b9，\u64cd\u4f5c\u7cfb\u7edf\u518d\u628a\u6570\u636e\u4ea4\u7ed9\u76f8\u5e94\u7684 Socket\u3002<\/p>\n

    1.2 \u4e3a\u4ec0\u4e48\u540c\u4e00\u4e2a\u7aef\u53e3\u53ef\u4ee5\u540c\u65f6\u63d0\u4f9b UDP \u548c TCP \u670d\u52a1<\/h4>\n

    \u56e0\u4e3a UDP \u4e0e TCP \u5c5e\u4e8e\u4e0d\u540c\u7684\u4f20\u8f93\u534f\u8bae\u3002\u4f8b\u5982 UDP \u7684 8888 \u548c TCP \u7684 8888，\u5e76\u4e0d\u662f\u540c\u4e00\u4e2a\u4f20\u8f93\u5c42\u5165\u53e3\u3002\u771f\u6b63\u8ba8\u8bba\u51b2\u7a81\u65f6，\u9700\u8981\u628a\u534f\u8bae\u4e5f\u8003\u8651\u8fdb\u6765\u3002<\/p>\n

    \u8fd9\u4e5f\u662f\u4e3a\u4ec0\u4e48\u670d\u52a1\u914d\u7f6e\u4e2d\u901a\u5e38\u4e0d\u53ea\u5199\u201c\u5f00\u653e 8888 \u7aef\u53e3\u201d，\u8fd8\u9700\u8981\u660e\u786e\u662f\u5f00\u653e 8888\/udp \u8fd8\u662f 8888\/tcp\u3002\u6211\u4eec\u7684\u793a\u4f8b\u5168\u90e8\u4f7f\u7528 UDP\u3002<\/p>\n

    1.3 UDP \u80fd\u63d0\u4f9b\u4ec0\u4e48<\/h4>\n

    UDP \u63d0\u4f9b\u6570\u636e\u62a5\u901a\u4fe1：\u5e94\u7528\u628a\u4e00\u6761\u6d88\u606f\u4f5c\u4e3a\u4e00\u4e2a\u6570\u636e\u62a5\u53d1\u51fa\u53bb，\u63a5\u6536\u7aef\u6309\u6570\u636e\u62a5\u8bfb\u53d6\u3002\u5b83\u6ca1\u6709 TCP \u90a3\u6837\u7684\u5efa\u8fde\u63e1\u624b，\u4e5f\u4e0d\u8d1f\u8d23\u4fdd\u8bc1\u6bcf\u6761\u6d88\u606f\u4e00\u5b9a\u9001\u8fbe\u3001\u6309\u53d1\u9001\u987a\u5e8f\u5230\u8fbe\u6216\u53ea\u5230\u8fbe\u4e00\u6b21\u3002Linux UDP \u624b\u518c<\/p>\n

    \u8fd9\u4e00\u70b9\u76f4\u63a5\u51b3\u5b9a\u4e86\u6211\u4eec\u540e\u9762\u4ee3\u7801\u7684\u8fb9\u754c：\u56de\u663e\u548c\u5b57\u5178\u9002\u5408\u6f14\u793a\u8bf7\u6c42\u4e0e\u54cd\u5e94，\u4f46\u201c\u5ba2\u6237\u7aef\u8d85\u65f6\u201d\u4e0d\u80fd\u76f4\u63a5\u89e3\u91ca\u6210\u201c\u670d\u52a1\u5668\u4e00\u5b9a\u6ca1\u6709\u5904\u7406\u201d\u3002\u5982\u679c\u54cd\u5e94\u4e22\u4e86，\u670d\u52a1\u5668\u53ef\u80fd\u5df2\u7ecf\u5b8c\u6210\u5904\u7406\u3002<\/p>\n

    \n

    \u4e8c\u3001Socket \u5230\u5e95\u662f\u4ec0\u4e48<\/h3>\n

    Socket，\u4e5f\u53eb\u5957\u63a5\u5b57，\u662f\u5e94\u7528\u8bbf\u95ee\u7f51\u7edc\u901a\u4fe1\u80fd\u529b\u7684\u4e00\u79cd\u63a5\u53e3\u4e0e\u5185\u6838\u5bf9\u8c61\u3002\u5e94\u7528\u7a0b\u5e8f\u4e0d\u5fc5\u81ea\u5df1\u9010\u5b57\u8282\u6784\u9020 IP \u6570\u636e\u5305，\u800c\u662f\u901a\u8fc7 Socket \u63a5\u53e3\u63d0\u51fa\u201c\u521b\u5efa\u901a\u4fe1\u7aef\u70b9\u3001\u7ed1\u5b9a\u5730\u5740\u3001\u53d1\u9001\u6d88\u606f\u3001\u63a5\u6536\u6d88\u606f\u201d\u7b49\u8bf7\u6c42\u3002<\/p>\n

    \u5728 Linux \u4e2d，\u521b\u5efa\u6210\u529f\u7684 Socket \u901a\u8fc7\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u8bbf\u95ee：<\/p>\n

    int<\/span> fd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_DGRAM,<\/span> 0<\/span>)<\/span>;<\/span>
    \nif<\/span> (<\/span>fd <<\/span> 0<\/span>)<\/span> {<\/span>
    \n \/\/ \u521b\u5efa\u5931\u8d25，\u9700\u8981\u68c0\u67e5 errno\u3002<\/span>
    \n}<\/span><\/p>\n

    \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

    2.1 \u4e09\u4e2a\u53c2\u6570\u5206\u522b\u5728\u9009\u4ec0\u4e48<\/h4>\n\n\u53c2\u6570\u672c\u6587\u53d6\u503c\u542b\u4e49<\/tr>\n\n\n\n\n
    domain<\/td>\nAF_INET<\/td>\n\u4f7f\u7528 IPv4 \u5730\u5740\u65cf<\/td>\n<\/tr>\n
    type<\/td>\nSOCK_DGRAM<\/td>\n\u4f7f\u7528\u6570\u636e\u62a5 Socket<\/td>\n<\/tr>\n
    protocol<\/td>\n0<\/td>\n\u8ba9\u7cfb\u7edf\u9009\u62e9\u8be5\u7ec4\u5408\u7684\u9ed8\u8ba4\u534f\u8bae，\u6b64\u5904\u4e3a UDP<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \u5982\u679c\u540e\u9762\u5b66\u4e60 TCP，\u5e38\u89c1\u7ec4\u5408\u4f1a\u53d8\u4e3a AF_INET + SOCK_STREAM + 0\u3002\u5730\u5740\u65cf\u51b3\u5b9a\u91c7\u7528\u54ea\u4e00\u7c7b\u5730\u5740，Socket \u7c7b\u578b\u51b3\u5b9a\u901a\u4fe1\u8bed\u4e49，\u534f\u8bae\u53c2\u6570\u8fdb\u4e00\u6b65\u6307\u5b9a\u5b9e\u73b0\u534f\u8bae\u3002<\/p>\n

    2.2 \u6587\u4ef6\u63cf\u8ff0\u7b26\u53ea\u662f\u5165\u53e3<\/h4>\n

    fd \u662f\u4e00\u4e2a\u6574\u6570，\u4e0d\u662f IP \u5730\u5740\u3001\u7aef\u53e3\u53f7，\u4e5f\u4e0d\u662f\u6570\u636e\u62a5\u672c\u8eab\u3002\u5b83\u662f\u5f53\u524d\u8fdb\u7a0b\u8bbf\u95ee\u67d0\u4e2a\u5185\u6838\u8d44\u6e90\u7684\u5165\u53e3\u3002<\/p>\n

    \u53ef\u4ee5\u628a\u8c03\u7528\u5173\u7cfb\u7406\u89e3\u4e3a：<\/p>\n

    \u5e94\u7528\u4fdd\u5b58 fd
    \n \u2192 \u8c03\u7528 sendto(fd, …)
    \n \u2192 \u5185\u6838\u627e\u5230\u5bf9\u5e94 Socket
    \n \u2192 \u6839\u636e\u76ee\u6807\u5730\u5740\u548c\u8def\u7531\u5b8c\u6210\u53d1\u9001<\/p>\n

    \u521b\u5efa\u6210\u529f\u53ea\u4ee3\u8868\u83b7\u5f97\u4e86\u4e00\u4e2a\u901a\u4fe1\u8d44\u6e90\u3002\u6b64\u65f6\u6211\u4eec\u8fd8\u6ca1\u6709\u4e3a\u670d\u52a1\u5668\u786e\u5b9a\u670d\u52a1\u7aef\u53e3，\u4e5f\u6ca1\u6709\u53d1\u9001\u4efb\u4f55\u6570\u636e\u3002<\/p>\n

    2.3 \u4e3a\u4ec0\u4e48\u4e0d\u80fd\u5199 if (fd <= 0)<\/h4>\n

    \u5931\u8d25\u8fd4\u56de\u7684\u662f -1，\u800c 0 \u4e5f\u662f\u5408\u6cd5\u6587\u4ef6\u63cf\u8ff0\u7b26\u3002\u5982\u679c\u8fdb\u7a0b\u539f\u672c\u5173\u95ed\u4e86\u6807\u51c6\u8f93\u5165，\u7cfb\u7edf\u5b8c\u5168\u53ef\u80fd\u628a 0 \u5206\u914d\u7ed9\u65b0\u521b\u5efa\u7684 Socket\u3002<\/p>\n

    \u56e0\u6b64\u5e94\u68c0\u67e5 fd < 0，\u5173\u95ed\u65f6\u68c0\u67e5 fd >= 0\u3002\u4e0d\u8981\u628a\u6807\u51c6\u8f93\u5165\u201c\u901a\u5e38\u4f7f\u7528 0\u201d\u7684\u4e60\u60ef，\u8bef\u5f53\u6210\u201c\u6240\u6709\u65b0\u8d44\u6e90\u90fd\u4e0d\u53ef\u80fd\u4f7f\u7528 0\u201d\u7684\u89c4\u5219\u3002<\/p>\n

    2.4 Socket \u7528\u5b8c\u4e5f\u8981\u5173\u95ed<\/h4>\n

    \u8bfe\u7a0b\u4ee3\u7801\u4e2d\u6709\u4e9b\u6790\u6784\u51fd\u6570\u4e3a\u7a7a\u3002\u5bf9\u5b66\u4e60\u63a5\u53e3\u800c\u8a00\u8fd9\u4e0d\u59a8\u788d\u7406\u89e3\u6d41\u7a0b，\u4f46\u6574\u7406\u6210\u53ef\u590d\u7528\u4ee3\u7801\u65f6，\u9700\u8981\u628a\u8d44\u6e90\u751f\u547d\u5468\u671f\u8865\u9f50\u3002<\/p>\n

    \u6211\u4eec\u91c7\u7528 RAII：\u5bf9\u8c61\u521b\u5efa\u65f6\u83b7\u5f97 Socket，\u5bf9\u8c61\u6790\u6784\u65f6\u8c03\u7528 close\u3002\u540c\u65f6\u7981\u7528\u590d\u5236，\u9632\u6b62\u4e24\u4e2a\u5bf9\u8c61\u4fdd\u5b58\u540c\u4e00\u4e2a fd，\u968f\u540e\u5404\u81ea\u5173\u95ed\u4e00\u6b21\u3002dup \u7b49\u5171\u4eab\u63cf\u8ff0\u7b26\u673a\u5236\u5c5e\u4e8e\u53e6\u4e00\u5c42\u8bbe\u8ba1，\u672c\u6587\u4e0d\u5c55\u5f00\u3002<\/p>\n

    \n

    \u4e09\u3001\u5148\u770b\u61c2 UDP \u901a\u4fe1\u7684\u6574\u4f53\u6d41\u7a0b<\/h3>\n

    \u7406\u89e3\u6bcf\u4e2a\u63a5\u53e3\u4e4b\u524d，\u5148\u628a\u5b8c\u6574\u7684\u8bf7\u6c42\u4e0e\u54cd\u5e94\u753b\u51fa\u6765\u3002<\/p>\n

    \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

    \u670d\u52a1\u5668\u7684\u57fa\u672c\u6d41\u7a0b\u662f：<\/p>\n

    socket \u2192 bind \u2192 recvfrom \u2192 \u5904\u7406\u6d88\u606f \u2192 sendto \u2192 \u7ee7\u7eed recvfrom<\/p>\n

    \u5ba2\u6237\u7aef\u7684\u57fa\u672c\u6d41\u7a0b\u662f：<\/p>\n

    socket \u2192 \u51c6\u5907\u670d\u52a1\u5668\u5730\u5740 \u2192 sendto \u2192 recvfrom \u2192 \u663e\u793a\u54cd\u5e94<\/p>\n

    3.1 \u4e3a\u4ec0\u4e48 UDP \u670d\u52a1\u5668\u6ca1\u6709 accept<\/h4>\n

    \u672c\u6587\u91c7\u7528\u672a\u8fde\u63a5\u7684 UDP Socket\u3002\u670d\u52a1\u5668\u6536\u5230\u7684\u6bcf\u4e2a\u6570\u636e\u62a5，\u90fd\u53ef\u80fd\u6765\u81ea\u4e0d\u540c\u5ba2\u6237\u7aef\u3002recvfrom \u4f1a\u628a\u672c\u6b21\u6d88\u606f\u7684\u6e90\u5730\u5740\u4e00\u8d77\u4ea4\u7ed9\u5e94\u7528，\u5e94\u7528\u518d\u51b3\u5b9a\u628a\u54cd\u5e94\u53d1\u7ed9\u8c01\u3002<\/p>\n

    \u5b83\u4e0d\u9700\u8981\u50cf\u5178\u578b TCP \u670d\u52a1\u5668\u90a3\u6837，\u901a\u8fc7 listen \/ accept \u4e3a\u6bcf\u4e2a\u8fde\u63a5\u5efa\u7acb\u72ec\u7acb\u7684\u901a\u4fe1 Socket\u3002\u4e00\u4e2a UDP Socket \u5c31\u53ef\u4ee5\u63a5\u6536\u591a\u4e2a\u5ba2\u6237\u7aef\u53d1\u6765\u7684\u6d88\u606f\u3002<\/p>\n

    3.2 \u5ba2\u6237\u7aef\u548c\u670d\u52a1\u5668\u7684\u533a\u522b\u5728\u54ea\u91cc<\/h4>\n

    \u4e24\u8fb9\u90fd\u521b\u5efa UDP Socket，\u90fd\u80fd\u53d1\u9001\u548c\u63a5\u6536\u3002\u533a\u522b\u4e3b\u8981\u6765\u81ea\u7a0b\u5e8f\u89d2\u8272\u4e0e\u7ea6\u5b9a：\u670d\u52a1\u5668\u5148\u5360\u7528\u4e00\u4e2a\u7a33\u5b9a\u7684\u670d\u52a1\u7aef\u53e3，\u7b49\u5f85\u8bf7\u6c42；\u5ba2\u6237\u7aef\u77e5\u9053\u8fd9\u4e2a\u670d\u52a1\u5165\u53e3，\u4e3b\u52a8\u53d1\u8d77\u8bf7\u6c42\u3002<\/p>\n

    \u6240\u4ee5，\u201c\u670d\u52a1\u5668\u53ea\u80fd\u6536\u3001\u5ba2\u6237\u7aef\u53ea\u80fd\u53d1\u201d\u662f\u9519\u8bef\u7684\u3002\u56de\u663e\u7a0b\u5e8f\u672c\u8eab\u5c31\u8981\u6c42\u4e24\u7aef\u90fd\u5177\u5907\u6536\u53d1\u80fd\u529b\u3002<\/p>\n

    3.3 UDP \u53ef\u4ee5\u8c03\u7528 connect \u5417<\/h4>\n

    \u53ef\u4ee5\u3002UDP \u7684 connect \u53ef\u4ee5\u8bbe\u7f6e\u9ed8\u8ba4\u5bf9\u7aef，\u4e4b\u540e\u4f7f\u7528 send \/ recv，\u4f46\u5b83\u4e0d\u4f1a\u5efa\u7acb TCP \u5f0f\u53ef\u9760\u8fde\u63a5，\u4e5f\u4e0d\u4f1a\u7ed9 UDP \u589e\u52a0\u53ef\u9760\u4ea4\u4ed8\u80fd\u529b\u3002\u672c\u6587\u4f7f\u7528 sendto \/ recvfrom，\u8ba9\u6bcf\u6b21\u901a\u4fe1\u7684\u76ee\u6807\u5730\u5740\u548c\u6e90\u5730\u5740\u90fd\u66f4\u76f4\u89c2\u3002Linux UDP \u624b\u518c<\/p>\n

    \n

    \u56db\u3001\u5730\u5740\u7ed3\u6784\u4e0e\u7f51\u7edc\u5b57\u8282\u5e8f<\/h3>\n

    \u5728\u547d\u4ee4\u884c\u91cc，\u6211\u4eec\u53ef\u4ee5\u8f93\u5165 127.0.0.1 8888；\u7cfb\u7edf\u8c03\u7528\u9700\u8981\u7684\u662f\u5177\u6709\u89c4\u5b9a\u5185\u5b58\u5e03\u5c40\u7684\u5730\u5740\u7ed3\u6784\u3002IPv4 \u7f16\u7a0b\u4e2d\u4e3b\u8981\u4f7f\u7528 sockaddr_in\u3002<\/p>\n

    sockaddr_in server{<\/span>}<\/span>;<\/span>
    \nserver.<\/span>sin_family =<\/span> AF_INET;<\/span>
    \nserver.<\/span>sin_port =<\/span> htons<\/span>(<\/span>8888<\/span>)<\/span>;<\/span>
    \nint<\/span> result =<\/span> inet_pton<\/span>(<\/span>AF_INET,<\/span> "127.0.0.1"<\/span>,<\/span> &<\/span>server.<\/span>sin_addr)<\/span>;<\/span><\/p>\n

    4.1 \u4e3a\u4ec0\u4e48\u5148\u5199 {}<\/h4>\n

    sockaddr_in server{}; \u4f1a\u5bf9\u7ed3\u6784\u4f53\u8fdb\u884c\u503c\u521d\u59cb\u5316，\u907f\u514d\u7559\u4e0b\u672a\u521d\u59cb\u5316\u5b57\u6bb5\u3002\u8bfe\u7a0b\u4e2d\u7684 bzero \u6216 memset \u4e5f\u80fd\u5b8c\u6210\u6e05\u96f6，\u4f46\u5728 C++ \u793a\u4f8b\u4e2d，\u82b1\u62ec\u53f7\u66f4\u76f4\u63a5\u3002<\/p>\n

    \u7ed3\u6784\u4f53\u4e2d\u7684\u4e09\u4e2a\u91cd\u70b9\u5b57\u6bb5\u5982\u4e0b：<\/p>\n\n\u5b57\u6bb5\u8868\u793a\u4ec0\u4e48\u586b\u5199\u65b9\u5f0f<\/tr>\n\n\n\n\n
    sin_family<\/td>\n\u5730\u5740\u65cf<\/td>\nAF_INET<\/td>\n<\/tr>\n
    sin_port<\/td>\n16 \u4f4d\u7aef\u53e3<\/td>\n\u4e3b\u673a\u5e8f\u6570\u503c\u7ecf\u8fc7 htons<\/td>\n<\/tr>\n
    sin_addr<\/td>\nIPv4 \u4e8c\u8fdb\u5236\u5730\u5740<\/td>\ninet_pton \u8f6c\u6362\u7ed3\u679c<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \u586b\u597d\u7ed3\u6784\u4f53，\u53ea\u662f\u51c6\u5907\u597d\u4e86\u5e94\u7528\u5185\u5b58\u4e2d\u7684\u53c2\u6570\u3002\u771f\u6b63\u628a\u672c\u5730\u5730\u5740\u914d\u7f6e\u5230 Socket \u4e0a，\u8981\u8c03\u7528 bind；\u4f5c\u4e3a\u76ee\u6807\u5730\u5740，\u5219\u628a\u5b83\u4ea4\u7ed9 sendto\u3002<\/p>\n

    4.2 sockaddr \u4e0e sockaddr_in \u7684\u5173\u7cfb<\/h4>\n

    Socket \u63a5\u53e3\u8981\u652f\u6301\u591a\u79cd\u5730\u5740\u65cf，\u56e0\u6b64\u53c2\u6570\u7ecf\u5e38\u4f7f\u7528\u901a\u7528\u7684 sockaddr*\u3002IPv4 \u4f7f\u7528 sockaddr_in，IPv6 \u4f7f\u7528 sockaddr_in6\u3002<\/p>\n

    sendto<\/span>(<\/span>fd,<\/span> data,<\/span> size,<\/span> 0<\/span>,<\/span>
    \n reinterpret_cast<\/span><<\/span>const<\/span> sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>server)<\/span>,<\/span> sizeof<\/span>(<\/span>server)<\/span>)<\/span>;<\/span><\/p>\n

    \u8fd9\u91cc\u7684\u8f6c\u6362\u6ca1\u6709\u628a IPv4 \u5730\u5740\u53d8\u6210\u53e6\u4e00\u79cd\u7f51\u7edc\u5730\u5740，\u4e5f\u6ca1\u6709\u8fdb\u884c\u5b57\u8282\u5e8f\u8f6c\u6362\u3002\u5b83\u53ea\u662f\u8ba9 IPv4 \u7ed3\u6784\u4f53\u7684\u5730\u5740\u6ee1\u8db3\u901a\u7528\u63a5\u53e3\u7684\u53c2\u6570\u7c7b\u578b\u8981\u6c42\u3002\u5730\u5740\u65cf\u548c\u957f\u5ea6\u544a\u8bc9\u5185\u6838\u5e94\u8be5\u600e\u6837\u89e3\u91ca\u8fd9\u6bb5\u6570\u636e\u3002<\/p>\n

    4.3 \u7f51\u7edc\u5b57\u8282\u5e8f\u89e3\u51b3\u4ec0\u4e48\u95ee\u9898<\/h4>\n

    \u5047\u8bbe\u4e00\u4e2a 16 \u4f4d\u6574\u6570\u662f 0x1234\u3002\u4e0d\u540c\u673a\u5668\u5728\u5185\u5b58\u4e2d\u53ef\u80fd\u5148\u653e 0x12，\u4e5f\u53ef\u80fd\u5148\u653e 0x34\u3002\u5982\u679c\u53d1\u9001\u7aef\u548c\u63a5\u6536\u7aef\u5404\u81ea\u6309\u81ea\u5df1\u7684\u4e60\u60ef\u89e3\u91ca\u540c\u6837\u7684\u4e24\u4e2a\u5b57\u8282，\u5c31\u53ef\u80fd\u5f97\u5230\u4e0d\u540c\u6570\u503c\u3002<\/p>\n

    \u7f51\u7edc\u4e2d\u7684\u76f8\u5173\u591a\u5b57\u8282\u6574\u6570\u4f7f\u7528\u7ea6\u5b9a\u7684\u5b57\u8282\u987a\u5e8f，\u4e5f\u5c31\u662f\u5927\u7aef\u5e8f\u3002\u4e8e\u662f\u6211\u4eec\u5728\u8fb9\u754c\u5904\u8fdb\u884c\u8f6c\u6362：<\/p>\n

    \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n\n\u51fd\u6570\u65b9\u5411\u5e38\u89c1\u7528\u9014<\/tr>\n\n\n\n\n\n
    htons<\/td>\nhost \u2192 network，16 \u4f4d<\/td>\n\u5199\u5165\u7aef\u53e3<\/td>\n<\/tr>\n
    ntohs<\/td>\nnetwork \u2192 host，16 \u4f4d<\/td>\n\u6253\u5370\u6536\u5230\u7684\u7aef\u53e3<\/td>\n<\/tr>\n
    htonl<\/td>\nhost \u2192 network，32 \u4f4d<\/td>\n\u5199\u5165\u4e3b\u673a\u5e8f\u7684 32 \u4f4d\u6570\u503c<\/td>\n<\/tr>\n
    ntohl<\/td>\nnetwork \u2192 host，32 \u4f4d<\/td>\n\u8bfb\u53d6\u7f51\u7edc\u5e8f\u7684 32 \u4f4d\u6570\u503c<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    h \u8868\u793a host，n \u8868\u793a network，s \u4e0e l \u5bf9\u5e94\u8fd9\u7ec4\u63a5\u53e3\u5904\u7406\u7684\u5bbd\u5ea6\u3002\u5373\u4f7f\u67d0\u53f0\u673a\u5668\u672c\u8eab\u5c31\u662f\u5927\u7aef，\u4e5f\u7167\u6837\u4f7f\u7528\u8fd9\u4e9b\u51fd\u6570；\u63a5\u53e3\u4f1a\u5b8c\u6210\u6b63\u786e\u7684\u8f6c\u6362，\u5e94\u7528\u4e0d\u9700\u8981\u731c\u6d4b\u8fd0\u884c\u5e73\u53f0\u3002<\/p>\n

    4.4 IP \u8f6c\u6362\u4e0e\u6574\u6570\u8f6c\u6362\u4e0d\u8981\u6df7\u5728\u4e00\u8d77<\/h4>\n

    inet_pton \u7684\u804c\u8d23\u662f\u628a\u53ef\u8bfb\u7684\u5730\u5740\u6587\u672c\u8f6c\u6210\u7f51\u7edc\u683c\u5f0f\u7684\u4e8c\u8fdb\u5236\u5730\u5740\u3002htons \u7684\u804c\u8d23\u662f\u628a\u7aef\u53e3\u8fd9\u6837\u7684\u6574\u6570\u4ece\u4e3b\u673a\u5e8f\u53d8\u6210\u7f51\u7edc\u5e8f\u3002<\/p>\n

    server.<\/span>sin_port =<\/span> htons<\/span>(<\/span>port)<\/span>;<\/span>
    \ninet_pton<\/span>(<\/span>AF_INET,<\/span> ip.<\/span>c_str<\/span>(<\/span>)<\/span>,<\/span> &<\/span>server.<\/span>sin_addr)<\/span>;<\/span><\/p>\n

    \u4e0d\u8981\u518d\u5bf9 inet_pton \u7684\u7ed3\u679c\u989d\u5916\u8c03\u7528\u4e00\u6b21 htonl，\u5426\u5219\u5728\u5c0f\u7aef\u5e73\u53f0\u4e0a\u53ef\u80fd\u628a\u5df2\u7ecf\u6b63\u786e\u7684\u5730\u5740\u53cd\u8fc7\u6765\u3002<\/p>\n

    4.5 inet_pton \u7684\u8fd4\u56de\u503c\u4e0d\u662f\u666e\u901a\u5e03\u5c14\u503c<\/h4>\n

    int<\/span> result =<\/span> inet_pton<\/span>(<\/span>AF_INET,<\/span> text.<\/span>c_str<\/span>(<\/span>)<\/span>,<\/span> &<\/span>address.<\/span>sin_addr)<\/span>;<\/span>
    \nif<\/span> (<\/span>result ==<\/span> 1<\/span>)<\/span> {<\/span>
    \n \/\/ \u8f6c\u6362\u6210\u529f\u3002<\/span>
    \n}<\/span> else<\/span> if<\/span> (<\/span>result ==<\/span> 0<\/span>)<\/span> {<\/span>
    \n \/\/ \u6587\u672c\u4e0d\u662f\u5408\u6cd5\u7684\u8be5\u5730\u5740\u65cf\u5730\u5740\u3002<\/span>
    \n}<\/span> else<\/span> {<\/span>
    \n \/\/ \u4e0d\u652f\u6301\u8be5\u5730\u5740\u65cf\u7b49\u9519\u8bef，\u68c0\u67e5 errno\u3002<\/span>
    \n}<\/span><\/p>\n

    \u4e0d\u80fd\u628a\u6240\u6709\u975e\u96f6\u503c\u90fd\u5f53\u6210\u6210\u529f，\u56e0\u4e3a -1 \u4e5f\u662f\u975e\u96f6\u3002POSIX \u5730\u5740\u8f6c\u6362\u8bf4\u660e<\/p>\n

    \u8fd8\u8981\u6ce8\u610f：inet_pton \u4e0d\u8d1f\u8d23 DNS \u89e3\u6790\u3002\u4f20\u5165 example.com \u4e0d\u4f1a\u5f97\u5230\u57df\u540d\u5bf9\u5e94\u7684 IP\u3002\u672c\u6587\u547d\u4ee4\u884c\u8981\u6c42\u586b\u5199\u6570\u5b57\u5f62\u5f0f\u7684 IPv4 \u5730\u5740，\u57df\u540d\u89e3\u6790\u7559\u5f85\u540e\u7eed\u8bfe\u7a0b\u3002<\/p>\n

    4.6 \u4e3a\u4ec0\u4e48\u8fd9\u91cc\u9009 inet_ntop<\/h4>\n

    \u6253\u5370\u5730\u5740\u65f6，\u6211\u4eec\u4f7f\u7528\u8c03\u7528\u65b9\u63d0\u4f9b\u7684\u7f13\u51b2\u533a：<\/p>\n

    char<\/span> ip[<\/span>INET_ADDRSTRLEN]<\/span>{<\/span>}<\/span>;<\/span>
    \nif<\/span> (<\/span>inet_ntop<\/span>(<\/span>AF_INET,<\/span> &<\/span>peer.<\/span>sin_addr,<\/span> ip,<\/span> sizeof<\/span>(<\/span>ip)<\/span>)<\/span> ==<\/span> nullptr<\/span>)<\/span> {<\/span>
    \n \/\/ \u8f6c\u6362\u5931\u8d25\u3002<\/span>
    \n}<\/span><\/p>\n

    INET_ADDRSTRLEN \u5305\u542b IPv4 \u6587\u672c\u548c\u7ed3\u5c3e\u7a7a\u5b57\u7b26\u9700\u8981\u7684\u7a7a\u95f4\u3002\u8fd4\u56de\u503c\u6210\u529f\u65f6\u6307\u5411\u6211\u4eec\u81ea\u5df1\u7684\u7f13\u51b2\u533a，\u5931\u8d25\u65f6\u4e3a nullptr\u3002inet_ntop \u624b\u518c<\/p>\n

    PDF \u8fd8\u8ba8\u8bba\u4e86 inet_ntoa\u3002\u5b83\u8fd4\u56de\u5e93\u5185\u90e8\u7f13\u51b2\u533a\u7684\u6307\u9488，\u4e0d\u9700\u8981\u8c03\u7528\u65b9 free；\u540e\u7eed\u8c03\u7528\u53ef\u80fd\u8986\u76d6\u4e4b\u524d\u7684\u5185\u5bb9，\u56e0\u6b64\u4e0d\u80fd\u628a\u4e24\u6b21\u8fd4\u56de\u7684\u6307\u9488\u5f53\u6210\u4e24\u4e2a\u72ec\u7acb\u5b57\u7b26\u4e32\u4fdd\u5b58\u3002\u73b0\u4ee3 Linux \u624b\u518c\u5c06\u76f8\u5173\u63a5\u53e3\u6807\u4e3a MT-Safe locale，\u6240\u4ee5\u4e5f\u4e0d\u80fd\u7b80\u5355\u5199\u6210\u201c\u6240\u6709 Linux \u5b9e\u73b0\u4e2d\u5b83\u90fd\u4e0d\u652f\u6301\u591a\u7ebf\u7a0b\u201d；\u5b89\u5168\u5c5e\u6027\u9700\u8981\u7ed3\u5408\u5177\u4f53\u5b9e\u73b0\u7406\u89e3\u3002inet \u624b\u518c<\/p>\n

    \u5de5\u7a0b\u4e0a\u66f4\u6e05\u6670\u7684\u9009\u62e9\u4ecd\u7136\u662f inet_ntop：\u7ed3\u679c\u5b58\u5728\u54ea\u5757\u5185\u5b58\u3001\u4f55\u65f6\u5931\u6548，\u7531\u8c03\u7528\u65b9\u660e\u786e\u63a7\u5236\u3002\u4e0d\u540c\u7ebf\u7a0b\u5404\u7528\u81ea\u5df1\u7684\u5c40\u90e8\u7f13\u51b2\u533a，\u4e5f\u66f4\u5bb9\u6613\u7406\u89e3\u3002<\/p>\n

    \n

    \u4e94\u3001\u670d\u52a1\u5668\u4e3a\u4ec0\u4e48\u8981 bind<\/h3>\n

    \u521b\u5efa Socket \u540e，\u670d\u52a1\u5668\u8fd8\u9700\u8981\u8ba9\u5ba2\u6237\u7aef\u77e5\u9053\u201c\u5e94\u8be5\u5f80\u54ea\u4e2a\u670d\u52a1\u5165\u53e3\u53d1\u9001\u6d88\u606f\u201d\u3002bind \u7684\u4f5c\u7528\u662f\u7ed9 Socket \u5173\u8054\u4e00\u4e2a\u672c\u5730\u5730\u5740\u3002<\/p>\n

    sockaddr_in local{<\/span>}<\/span>;<\/span>
    \nlocal.<\/span>sin_family =<\/span> AF_INET;<\/span>
    \nlocal.<\/span>sin_port =<\/span> htons<\/span>(<\/span>8888<\/span>)<\/span>;<\/span>
    \nlocal.<\/span>sin_addr.<\/span>s_addr =<\/span> htonl<\/span>(<\/span>INADDR_ANY)<\/span>;<\/span><\/p>\n

    if<\/span> (<\/span>::<\/span>bind<\/span>(<\/span>fd,<\/span> reinterpret_cast<\/span><<\/span>const<\/span> sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>local)<\/span>,<\/span> sizeof<\/span>(<\/span>local)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
    \n \/\/ \u7ed1\u5b9a\u5931\u8d25\u3002<\/span>
    \n}<\/span><\/p>\n

    5.1 \u672c\u5730\u5730\u5740\u548c\u76ee\u6807\u5730\u5740\u5fc5\u987b\u5206\u6e05<\/h4>\n

    \u8fd9\u662f\u521d\u5b66\u7f51\u7edc\u7f16\u7a0b\u6700\u5bb9\u6613\u7ed5\u6655\u7684\u4e00\u70b9：<\/p>\n

      \n
    • bind \u91cc\u7684\u5730\u5740\u56de\u7b54：\u5f53\u524d Socket \u5728\u672c\u673a\u4f7f\u7528\u54ea\u4e2a\u5730\u5740\u4e0e\u7aef\u53e3；<\/li>\n
    • sendto \u91cc\u7684\u5730\u5740\u56de\u7b54：\u5f53\u524d\u8fd9\u6761\u6d88\u606f\u8981\u53d1\u7ed9\u54ea\u4e2a\u5bf9\u7aef；<\/li>\n
    • recvfrom \u8f93\u51fa\u7684\u5730\u5740\u56de\u7b54：\u5f53\u524d\u6536\u5230\u7684\u6d88\u606f\u662f\u8c01\u53d1\u6765\u7684\u3002<\/li>\n<\/ul>\n

      \u5ba2\u6237\u7aef\u5e94\u8be5\u628a\u670d\u52a1\u5668\u5730\u5740\u4ea4\u7ed9 sendto，\u800c\u4e0d\u662f\u5c1d\u8bd5\u628a\u670d\u52a1\u5668 IP \u7ed1\u5b9a\u5230\u81ea\u5df1\u7684 Socket \u4e0a\u3002<\/p>\n

      \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

      5.2 INADDR_ANY \u8868\u793a\u4ec0\u4e48<\/h4>\n

      INADDR_ANY \u901a\u5e38\u5bf9\u5e94 0.0.0.0\u3002\u4f5c\u4e3a IPv4 \u7684\u7ed1\u5b9a\u5730\u5740，\u5b83\u8868\u793a\u901a\u914d\u672c\u5730\u63a5\u53e3\u5730\u5740，\u7701\u53bb\u6307\u5b9a\u67d0\u4e00\u4e2a\u672c\u5730 IP \u7684\u6b65\u9aa4\u3002Linux IP \u624b\u518c<\/p>\n

      \u5b83\u4e0d\u662f\u201c\u5141\u8bb8\u4efb\u4f55\u4eba\u901a\u8fc7\u8ba4\u8bc1\u201d\u7684\u5f00\u5173，\u4e5f\u4e0d\u662f\u201c\u670d\u52a1\u5668\u7684\u53ef\u8bbf\u95ee\u516c\u7f51 IP\u201d\u3002\u6570\u636e\u80fd\u5426\u4ece\u5916\u90e8\u5230\u8fbe，\u8fd8\u53d7\u5230\u8def\u7531\u3001\u9632\u706b\u5899\u3001\u4e91\u5b89\u5168\u7ec4\u548c\u7f51\u7edc\u6620\u5c04\u7b49\u6761\u4ef6\u5f71\u54cd\u3002<\/p>\n

      \u5ba2\u6237\u7aef\u53d1\u9001\u65f6\u4ecd\u8981\u4f7f\u7528\u5177\u4f53\u7684\u53ef\u8fbe\u76ee\u6807\u5730\u5740\u3002\u672c\u673a\u6d4b\u8bd5\u7528 127.0.0.1；\u5c40\u57df\u7f51\u6d4b\u8bd5\u4f7f\u7528\u670d\u52a1\u5668\u7684\u5c40\u57df\u7f51\u5730\u5740；\u8de8\u516c\u7f51\u6d4b\u8bd5\u4f7f\u7528\u76f8\u5e94\u7684\u53ef\u8fbe\u5165\u53e3\u3002<\/p>\n

      5.3 \u4e91\u670d\u52a1\u5668\u4e3a\u4f55\u53ef\u80fd\u4e0d\u80fd\u7ed1\u5b9a\u516c\u7f51 IP<\/h4>\n

      \u5728\u67d0\u4e9b\u4e91\u7f51\u7edc\u4e2d，\u5916\u90e8\u770b\u5230\u7684\u516c\u7f51 IP \u7531\u5e73\u53f0\u901a\u8fc7\u6620\u5c04\u63d0\u4f9b，\u5b83\u672a\u5fc5\u76f4\u63a5\u914d\u7f6e\u5728\u865a\u62df\u673a\u7684\u7f51\u7edc\u63a5\u53e3\u4e0a\u3002\u6b64\u65f6\u5e94\u7528\u8bd5\u56fe\u7ed1\u5b9a\u8fd9\u4e2a\u516c\u7f51 IP，\u53ef\u80fd\u56e0\u4e3a\u5b83\u4e0d\u662f\u672c\u673a\u5730\u5740\u800c\u5931\u8d25\u3002<\/p>\n

      \u6240\u4ee5\u5e94\u5148\u67e5\u770b\u4e3b\u673a\u5b9e\u9645\u62e5\u6709\u7684\u5730\u5740，\u518d\u51b3\u5b9a\u7ed1\u5b9a\u7b56\u7565\u3002\u6559\u5b66\u793a\u4f8b\u4f7f\u7528 INADDR_ANY \u4fbf\u4e8e\u5728\u591a\u79cd\u73af\u5883\u4e2d\u8fd0\u884c；\u5982\u679c\u53ea\u5e0c\u671b\u670d\u52a1\u80fd\u5728\u672c\u673a\u8bbf\u95ee，\u5219\u5e94\u663e\u5f0f\u7ed1\u5b9a 127.0.0.1\u3002\u5b9e\u9645\u90e8\u7f72\u4e5f\u53ef\u4ee5\u6309\u4e1a\u52a1\u8981\u6c42\u7ed1\u5b9a\u67d0\u4e2a\u672c\u5730\u63a5\u53e3\u5730\u5740\u3002<\/p>\n

      \u8fd9\u6bd4\u201c\u4e91\u670d\u52a1\u5668\u6c38\u8fdc\u4e0d\u80fd\u7ed1\u5b9a\u516c\u7f51 IP\u201d\u66f4\u51c6\u786e：\u5173\u952e\u5728\u4e8e\u8be5 IP \u662f\u5426\u5b9e\u9645\u5c5e\u4e8e\u672c\u673a\u63a5\u53e3\u4ee5\u53ca\u7cfb\u7edf\u914d\u7f6e\u3002<\/p>\n

      5.4 \u5ba2\u6237\u7aef\u8981\u4e0d\u8981\u663e\u5f0f bind<\/h4>\n

      \u5bf9\u4e8e\u672c\u6587\u56de\u663e\u5ba2\u6237\u7aef，\u901a\u5e38\u4e0d\u9700\u8981\u663e\u5f0f\u8c03\u7528 bind\u3002\u672a\u7ed1\u5b9a\u7684 UDP Socket \u5728\u9996\u6b21\u53d1\u9001\u65f6，\u7531\u7cfb\u7edf\u5206\u914d\u53ef\u7528\u7684\u672c\u5730\u4e34\u65f6\u7aef\u53e3\u3002Linux UDP \u624b\u518c<\/p>\n

      \u5ba2\u6237\u7aef\u4e5f\u9700\u8981\u4e00\u4e2a\u53ef\u4ee5\u63a5\u6536\u54cd\u5e94\u7684\u672c\u5730\u7aef\u70b9，\u53ea\u662f\u8fd9\u4e2a\u9009\u62e9\u4ea4\u7ed9\u5185\u6838\u5b8c\u6210\u3002\u670d\u52a1\u5668\u8bfb\u53d6\u8bf7\u6c42\u7684\u6e90\u5730\u5740\u540e，\u5c31\u77e5\u9053\u54cd\u5e94\u5e94\u8be5\u53d1\u5230\u54ea\u91cc\u3002<\/p>\n

      \u6240\u8c13\u201c\u4e34\u65f6\u7aef\u53e3\u201d，\u4e0d\u662f\u6bcf\u53d1\u4e00\u6761\u6d88\u606f\u5c31\u6362\u4e00\u4e2a\u7aef\u53e3\u3002\u53ea\u8981\u5ba2\u6237\u7aef\u7ee7\u7eed\u4f7f\u7528\u540c\u4e00\u4e2a Socket，\u5b83\u901a\u5e38\u4f1a\u7ee7\u7eed\u4f7f\u7528\u5df2\u5206\u914d\u7684\u7aef\u53e3\u3002<\/p>\n

      5.5 \u4ec0\u4e48\u60c5\u51b5\u4e0b\u5ba2\u6237\u7aef\u4f1a\u4e3b\u52a8\u7ed1\u5b9a<\/h4>\n

      \u5f53\u534f\u8bae\u8981\u6c42\u56fa\u5b9a\u5ba2\u6237\u7aef\u7aef\u53e3\u3001\u5e0c\u671b\u9650\u5236\u672c\u5730\u63a5\u53e3，\u6216\u9700\u8981\u5728\u7b2c\u4e00\u6b21\u53d1\u9001\u4e4b\u524d\u542f\u52a8\u72ec\u7acb\u63a5\u6536\u6d41\u7a0b\u65f6，\u90fd\u53ef\u4ee5\u663e\u5f0f\u7ed1\u5b9a\u3002<\/p>\n

      \u4e0b\u7bc7\u7684\u804a\u5929\u5ba4\u5ba2\u6237\u7aef\u4f7f\u7528：<\/p>\n

      socket.<\/span>BindAny<\/span>(<\/span>0<\/span>)<\/span>;<\/span><\/p>\n

      \u7ed1\u5b9a\u7aef\u53e3 0 \u8868\u793a\u8ba9\u7cfb\u7edf\u9009\u62e9\u53ef\u7528\u7aef\u53e3\u3002\u8fd9\u4ecd\u7136\u662f\u5ba2\u6237\u7aef\u81ea\u5df1\u7684\u672c\u5730\u7aef\u53e3，\u4e0e\u670d\u52a1\u5668\u7684 8888 \u6ca1\u6709\u51b2\u7a81\u5173\u7cfb\u3002<\/p>\n

      5.6 \u5982\u4f55\u89c2\u5bdf\u5185\u6838\u5206\u914d\u7684\u7aef\u53e3<\/h4>\n

      \u8c03\u7528 getsockname \u53ef\u4ee5\u8bfb\u53d6 Socket \u7684\u672c\u5730\u5730\u5740\u3002\u6211\u4eec\u7684\u5ba2\u6237\u7aef\u5728\u53d1\u9001\u540e\u6253\u5370\u5b83，\u8ba9\u201c\u9690\u5f0f\u7ed1\u5b9a\u201d\u4e0d\u518d\u53ea\u662f\u6587\u5b57\u7ed3\u8bba\u3002<\/p>\n

      \u5982\u679c Socket \u7ed1\u5b9a\u901a\u914d\u5730\u5740，\u67e5\u8be2\u7ed3\u679c\u4e2d\u7684 IP \u53ef\u80fd\u4ecd\u663e\u793a 0.0.0.0；\u5b9e\u9645\u51fa\u7ad9\u6570\u636e\u62a5\u7684\u6e90\u5730\u5740\u7531\u8def\u7531\u7b49\u56e0\u7d20\u51b3\u5b9a，\u4e0d\u80fd\u76f4\u63a5\u628a\u8fd9\u4e2a\u901a\u914d\u5730\u5740\u5f53\u6210\u7ebf\u4e0a\u6e90 IP\u3002<\/p>\n

      \n

      \u516d\u3001sendto \u4e0e recvfrom \u7684\u53c2\u6570\u600e\u4e48\u8bfb<\/h3>\n

      \u8fd9\u4e24\u4e2a\u51fd\u6570\u770b\u8d77\u6765\u53c2\u6570\u8f83\u591a，\u4f46\u628a\u5b83\u4eec\u62c6\u6210\u201c\u8d44\u6e90\u3001\u6570\u636e\u3001\u5730\u5740\u201d\u4e09\u7ec4\u5c31\u5f88\u597d\u7406\u89e3\u3002<\/p>\n

      6.1 sendto：\u6307\u5b9a\u4e00\u6761\u6d88\u606f\u548c\u5b83\u7684\u76ee\u7684\u5730<\/h4>\n

      ssize_t n =<\/span> sendto<\/span>(<\/span>
      \n fd,<\/span> \/\/ \u4f7f\u7528\u54ea\u4e2a Socket<\/span>
      \n message.<\/span>data<\/span>(<\/span>)<\/span>,<\/span> \/\/ \u6d88\u606f\u4ece\u54ea\u91cc\u5f00\u59cb<\/span>
      \n message.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> \/\/ \u53d1\u9001\u591a\u5c11\u5b57\u8282<\/span>
      \n 0<\/span>,<\/span> \/\/ \u672c\u6b21\u53d1\u9001\u6807\u5fd7<\/span>
      \n reinterpret_cast<\/span><<\/span>const<\/span> sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>server)<\/span>,<\/span>
      \n sizeof<\/span>(<\/span>server)<\/span> \/\/ \u76ee\u6807\u5730\u5740\u7ed3\u6784\u7684\u5927\u5c0f<\/span>
      \n)<\/span>;<\/span><\/p>\n

      \u8fd4\u56de\u503c\u7c7b\u578b\u662f ssize_t，\u56e0\u4e3a\u5b83\u65e2\u8981\u8868\u793a\u6210\u529f\u65f6\u7684\u5b57\u8282\u6570，\u4e5f\u8981\u8868\u793a\u5931\u8d25\u65f6\u7684 -1\u3002\u4e0d\u8981\u4e00\u5f00\u59cb\u5c31\u628a\u5b83\u653e\u8fdb\u65e0\u7b26\u53f7\u7684 size_t \u4e2d，\u5426\u5219 -1 \u53ef\u80fd\u53d8\u6210\u4e00\u4e2a\u5f88\u5927\u7684\u6b63\u6570\u3002<\/p>\n

      \u53d1\u9001\u6210\u529f\u53ea\u8bf4\u660e\u8fd9\u6b21\u8c03\u7528\u88ab\u672c\u5730\u7cfb\u7edf\u63a5\u53d7，\u4e0d\u7b49\u4e8e\u5df2\u7ecf\u6536\u5230\u8fdc\u7aef\u5e94\u7528\u7684\u786e\u8ba4\u3002\u5982\u679c\u4e1a\u52a1\u9700\u8981\u786e\u8ba4，\u9700\u8981\u8bbe\u8ba1\u5bf9\u5e94\u7684\u54cd\u5e94\u6216\u786e\u8ba4\u6d88\u606f\u3002<\/p>\n

      6.2 \u4e3a\u4ec0\u4e48\u4e0d\u7528 strlen<\/h4>\n

      \u5b57\u7b26\u4e32\u5bf9\u8c61\u5df2\u7ecf\u8bb0\u5f55\u4e86\u5b57\u8282\u957f\u5ea6\u3002strlen \u626b\u63cf\u5230\u7b2c\u4e00\u4e2a \\\\0 \u5c31\u505c\u6b62，\u4e0d\u80fd\u8868\u8fbe\u4e2d\u95f4\u542b\u6709\u96f6\u5b57\u8282\u7684\u5b8c\u6574\u6570\u636e\u3002<\/p>\n

      \u4f8b\u5982\u4e09\u4e2a\u5b57\u8282 A\u3001\\\\0\u3001B，\u4f7f\u7528 strlen \u53ea\u80fd\u5f97\u5230 1；\u4f7f\u7528 std::string \u7684 size() \u53ef\u4ee5\u5f97\u5230 3\u3002\u8fd9\u91cc\u6309\u5b9e\u9645\u957f\u5ea6\u53d1\u9001，\u65e2\u9002\u7528\u4e8e\u666e\u901a\u6587\u672c，\u4e5f\u4fdd\u7559\u4e86\u4e8c\u8fdb\u5236\u6d88\u606f\u7684\u80fd\u529b\u3002<\/p>\n

      6.3 recvfrom：\u8bfb\u6d88\u606f，\u540c\u65f6\u5f97\u5230\u53d1\u9001\u8005<\/h4>\n

      char<\/span> buffer[<\/span>4096<\/span>]<\/span>;<\/span>
      \nsockaddr_in peer{<\/span>}<\/span>;<\/span>
      \nsocklen_t length =<\/span> sizeof<\/span>(<\/span>peer)<\/span>;<\/span><\/p>\n

      ssize_t n =<\/span> recvfrom<\/span>(<\/span>
      \n fd,<\/span> buffer,<\/span> sizeof<\/span>(<\/span>buffer)<\/span>,<\/span> 0<\/span>,<\/span>
      \n reinterpret_cast<\/span><<\/span>sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>peer)<\/span>,<\/span> &<\/span>length
      \n)<\/span>;<\/span><\/p>\n

      \u4e0e sendto \u4e0d\u540c，peer \u662f\u8f93\u51fa\u4f4d\u7f6e\u3002\u8c03\u7528\u524d\u6211\u4eec\u4e0d\u5fc5\u77e5\u9053\u662f\u8c01\u53d1\u6765\u6d88\u606f，\u8c03\u7528\u540e\u5b83\u5305\u542b\u8fd9\u6b21\u6570\u636e\u62a5\u7684\u6e90\u5730\u5740\u3002<\/p>\n

      \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

      6.4 length \u4e3a\u4ec0\u4e48\u5fc5\u987b\u521d\u59cb\u5316<\/h4>\n

      length \u662f\u201c\u503c\u2014\u7ed3\u679c\u201d\u53c2\u6570：\u8c03\u7528\u524d，\u5b83\u8868\u793a\u5e94\u7528\u63d0\u4f9b\u7684\u5730\u5740\u7f13\u51b2\u533a\u6709\u591a\u5927；\u8c03\u7528\u540e，\u5b83\u8868\u793a\u5b9e\u9645\u5730\u5740\u957f\u5ea6\u3002\u5e94\u4f7f\u7528 socklen_t，\u5e76\u5728\u6bcf\u6b21\u8c03\u7528\u524d\u521d\u59cb\u5316\u3002recvfrom \u624b\u518c<\/p>\n

      for<\/span> (<\/span>;<\/span>;<\/span>)<\/span> {<\/span>
      \n sockaddr_in peer{<\/span>}<\/span>;<\/span>
      \n socklen_t length =<\/span> sizeof<\/span>(<\/span>peer)<\/span>;<\/span>
      \n \/\/ recvfrom(…, &length)<\/span>
      \n}<\/span><\/p>\n

      \u8fd9\u4e2a\u957f\u5ea6\u63cf\u8ff0\u7684\u662f\u5730\u5740\u7ed3\u6784，\u4e0d\u662f\u6d88\u606f\u5185\u5bb9\u3002\u6d88\u606f\u957f\u5ea6\u7531\u51fd\u6570\u8fd4\u56de\u503c\u7ed9\u51fa\u3002\u6df7\u6dc6\u4e24\u8005，\u5bb9\u6613\u628a\u201c\u5730\u5740\u6709 16 \u5b57\u8282\u201d\u8bef\u5199\u6210\u201c\u53ea\u63a5\u6536 16 \u5b57\u8282\u6d88\u606f\u201d\u3002<\/p>\n

      6.5 \u6ca1\u6709\u6d88\u606f\u65f6\u4f1a\u600e\u6837<\/h4>\n

      \u672c\u6587\u4f7f\u7528\u963b\u585e Socket\u3002\u6ca1\u6709\u6d88\u606f\u5230\u8fbe\u65f6，recvfrom \u9ed8\u8ba4\u4f1a\u7b49\u5f85，\u7a0b\u5e8f\u505c\u5728\u8fd9\u4e00\u884c，\u5e76\u4e0d\u4ee3\u8868 CPU \u4e00\u76f4\u5fd9\u4e8e\u5faa\u73af\u68c0\u67e5\u3002<\/p>\n

      \u5ba2\u6237\u7aef\u53ef\u4ee5\u8bbe\u7f6e SO_RCVTIMEO，\u8ba9\u7b49\u5f85\u6709\u65f6\u95f4\u4e0a\u9650\u3002\u793a\u4f8b\u8bbe\u7f6e\u4e09\u79d2\u63a5\u6536\u8d85\u65f6，\u8d85\u65f6\u901a\u5e38\u8868\u73b0\u4e3a -1，\u5e76\u8bbe\u7f6e EAGAIN \u6216 EWOULDBLOCK\u3002\u5e95\u5c42\u5c01\u88c5\u628a\u8fd9\u79cd\u60c5\u51b5\u8f6c\u6362\u6210 false，\u4fbf\u4e8e\u4e1a\u52a1\u5c42\u533a\u522b\u201c\u6ca1\u6709\u7b49\u5230\u6d88\u606f\u201d\u548c\u201c\u53d1\u751f\u5176\u4ed6\u9519\u8bef\u201d\u3002<\/p>\n

      \n

      \u4e03\u3001UDP \u7684\u6d88\u606f\u8fb9\u754c\u4e0e\u8fd4\u56de\u503c\u9677\u9631<\/h3>\n

      Socket \u63a5\u53e3\u80fd\u591f\u8c03\u7528\u6210\u529f，\u53ea\u662f\u7b2c\u4e00\u6b65\u3002\u8981\u5199\u5bf9\u7a0b\u5e8f，\u8fd8\u5fc5\u987b\u7406\u89e3\u8fd4\u56de\u503c\u4e0e\u6570\u636e\u62a5\u8fb9\u754c\u3002<\/p>\n

      \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

      7.1 \u4e00\u4e2a\u63a5\u6536\u8c03\u7528\u8bfb\u53d6\u4e00\u4e2a\u6570\u636e\u62a5<\/h4>\n

      \u5047\u8bbe\u5ba2\u6237\u7aef\u8fde\u7eed\u53d1\u9001 hello \u548c world \u4e24\u4e2a\u6570\u636e\u62a5\u3002\u5728\u6570\u636e\u62a5\u5230\u8fbe\u7684\u524d\u63d0\u4e0b，\u63a5\u6536\u7aef\u6309\u4e24\u6761\u6d88\u606f\u8bfb\u53d6；\u4e0d\u4f1a\u56e0\u4e3a\u4e24\u4e2a\u5305\u5728\u65f6\u95f4\u4e0a\u63a5\u8fd1，\u5c31\u81ea\u52a8\u628a\u5b83\u4eec\u62fc\u6210\u4e00\u4e2a helloworld\u3002<\/p>\n

      \u4f46\u8fd9\u4e0d\u4fdd\u8bc1\u7b2c\u4e8c\u4e2a\u5305\u4e00\u5b9a\u5728\u7b2c\u4e00\u4e2a\u5305\u4e4b\u540e\u5230\u8fbe\u3002\u4fdd\u7559\u6d88\u606f\u8fb9\u754c\u4e0e\u4fdd\u8bc1\u6d88\u606f\u987a\u5e8f\u662f\u4e24\u4ef6\u4e0d\u540c\u7684\u4e8b\u3002<\/p>\n

      7.2 \u7f13\u51b2\u533a\u592a\u5c0f，\u4e0d\u80fd\u4e0b\u6b21\u518d\u8bfb\u5269\u4f59\u90e8\u5206<\/h4>\n

      \u5982\u679c\u4e00\u4e2a\u6570\u636e\u62a5\u6709 2000 \u5b57\u8282，\u800c\u672c\u6b21\u53ea\u63d0\u4f9b 1024 \u5b57\u8282\u7f13\u51b2\u533a，\u8d85\u8fc7\u7684\u90e8\u5206\u4e0d\u4f1a\u50cf\u666e\u901a\u6587\u4ef6\u90a3\u6837\u7559\u7740\u7b49\u4e0b\u6b21\u7ee7\u7eed\u8bfb\u53d6\u3002\u5e94\u7528\u5fc5\u987b\u9884\u5148\u7ea6\u5b9a\u6d88\u606f\u4e0a\u9650，\u6216\u8005\u68c0\u67e5\u622a\u65ad\u60c5\u51b5\u3002<\/p>\n

      \u672c\u6587 Linux \u5c01\u88c5\u5728 recvfrom \u4e2d\u4f7f\u7528 MSG_TRUNC，\u4f7f\u8fd4\u56de\u503c\u80fd\u591f\u53cd\u6620\u539f\u59cb\u6570\u636e\u62a5\u957f\u5ea6；\u5982\u679c\u5b83\u5927\u4e8e\u7f13\u51b2\u533a\u5927\u5c0f，\u5c31\u4e22\u5f03\u672c\u6761\u6d88\u606f，\u907f\u514d\u5bf9\u622a\u65ad\u540e\u7684\u5185\u5bb9\u8fdb\u884c\u5904\u7406\u3002\u8fd9\u4e2a\u5177\u4f53\u7528\u6cd5\u662f Linux \u8bed\u4e49，\u4e0d\u5e94\u76f4\u63a5\u5047\u5b9a\u6240\u6709\u5e73\u53f0\u90fd\u76f8\u540c\u3002recvfrom \u624b\u518c<\/p>\n

      \u5c24\u5176\u6ce8\u610f：\u4f7f\u7528\u8fd9\u79cd\u65b9\u5f0f\u540e，\u8fd4\u56de\u503c\u53ef\u80fd\u5927\u4e8e\u7f13\u51b2\u533a\u5bb9\u91cf\u3002\u5fc5\u987b\u5148\u6bd4\u8f83\u957f\u5ea6，\u518d\u6784\u9020\u5b57\u7b26\u4e32，\u5426\u5219\u4f1a\u8bfb\u5230\u7f13\u51b2\u533a\u4e4b\u5916\u3002<\/p>\n

      7.3 UDP \u63a5\u6536\u8fd4\u56de 0，\u53ef\u80fd\u662f\u6b63\u5e38\u6d88\u606f<\/h4>\n

      \u8bfe\u7a0b\u4e2d\u7684\u4e00\u4e9b\u793a\u4f8b\u53ea\u5728 n > 0 \u65f6\u5904\u7406\u6d88\u606f\u3002\u8fd9\u4f1a\u5ffd\u7565\u5408\u6cd5\u7684\u96f6\u957f\u5ea6 UDP \u6570\u636e\u62a5\u3002<\/p>\n

      \u5728 UDP \u7a0b\u5e8f\u91cc，\u6211\u4eec\u5e94\u533a\u5206：<\/p>\n\n\u7ed3\u679c\u5e94\u8be5\u600e\u4e48\u7406\u89e3<\/tr>\n\n\n\n\n
      n > 0<\/td>\n\u6536\u5230\u975e\u7a7a\u6570\u636e\u62a5<\/td>\n<\/tr>\n
      n == 0<\/td>\n\u53ef\u4ee5\u8868\u793a\u6536\u5230\u7a7a\u6570\u636e\u62a5<\/td>\n<\/tr>\n
      n < 0<\/td>\n\u68c0\u67e5\u9519\u8bef\u7801<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      \u4e0d\u8981\u628a TCP \u7684\u201c\u6709\u5e8f\u5173\u95ed\u540e\u8bfb\u5230 0\u201d\u76f4\u63a5\u5957\u5230 UDP \u4e0a\u3002UDP \u6ca1\u6709\u5bf9\u5e94\u7684\u8fde\u63a5\u5173\u95ed\u901a\u77e5\u3002recv \u624b\u518c<\/p>\n

      \u6211\u4eec\u7684\u5c01\u88c5\u8fd4\u56de true \u8868\u793a\u6210\u529f\u6536\u5230\u4e00\u6761\u6570\u636e\u62a5，\u7a7a\u4e0d\u7a7a\u7531 message.size() \u8868\u793a\u3002\u8fd9\u6837\u72b6\u6001\u548c\u6570\u636e\u5185\u5bb9\u5c31\u4e0d\u4f1a\u6df7\u5728\u4e00\u8d77\u3002<\/p>\n

      7.4 \u6ca1\u6709\u7ed3\u5c3e\u96f6\u5b57\u7b26\u4e5f\u80fd\u5b89\u5168\u4fdd\u5b58\u6587\u672c<\/h4>\n

      \u8bfe\u7a0b\u5e38\u89c1\u5199\u6cd5\u662f\u9884\u7559\u4e00\u4e2a\u5b57\u8282，\u7136\u540e\u5199 buffer[n] = '\\\\0'\u3002\u8fd9\u9002\u7528\u4e8e\u968f\u540e\u6309 C \u5b57\u7b26\u4e32\u4f7f\u7528\u7f13\u51b2\u533a\u7684\u60c5\u51b5\u3002<\/p>\n

      \u6211\u4eec\u91c7\u7528\u53e6\u4e00\u79cd\u65b9\u5f0f：<\/p>\n

      message.<\/span>assign<\/span>(<\/span>buffer,<\/span> static_cast<\/span><<\/span>std::<\/span>size_t><\/span><\/span><\/span>(<\/span>n)<\/span>)<\/span>;<\/span><\/p>\n

      \u5b83\u6839\u636e\u957f\u5ea6\u62f7\u8d1d\u5185\u5bb9，\u4e0d\u8981\u6c42\u8f93\u5165\u7f13\u51b2\u533a\u4ee5 \\\\0 \u7ed3\u675f，\u4e5f\u80fd\u6b63\u786e\u4fdd\u5b58\u5185\u90e8\u5305\u542b\u96f6\u5b57\u8282\u7684\u6570\u636e\u3002<\/p>\n

      7.5 \u5927\u7f13\u51b2\u533a\u4e0d\u4ee3\u8868\u9002\u5408\u53d1\u5927 UDP \u5305<\/h4>\n

      \u672c\u6587\u63a5\u6536\u7f13\u51b2\u533a\u4e3a 4096 \u5b57\u8282，\u4ea4\u4e92\u5ba2\u6237\u7aef\u9650\u5236\u8f93\u5165\u4e3a 1024 \u5b57\u8282\u3002\u8fd9\u662f\u6f14\u793a\u7a0b\u5e8f\u7684\u5e94\u7528\u7ea6\u5b9a，\u5e76\u4e0d\u662f UDP \u7684\u534f\u8bae\u6700\u5927\u957f\u5ea6\u3002<\/p>\n

      \u771f\u5b9e\u7f51\u7edc\u7684\u8def\u5f84 MTU \u53ef\u80fd\u66f4\u5c0f\u3002\u6d88\u606f\u8fc7\u5927\u4f1a\u589e\u52a0\u5206\u7247\u98ce\u9669，\u6216\u8ba9\u53d1\u9001\u56e0 EMSGSIZE \u5931\u8d25\u3002\u4e1a\u52a1\u5e94\u4f9d\u636e\u5b9e\u9645\u7f51\u7edc\u6761\u4ef6\u63a7\u5236\u5305\u5927\u5c0f，\u4e0d\u80fd\u56e0\u4e3a\u63a5\u6536\u6570\u7ec4\u5f00\u5f97\u5f88\u5927，\u5c31\u5ffd\u89c6\u94fe\u8def\u9650\u5236\u3002<\/p>\n

      7.6 \u8d85\u65f6\u4e4b\u540e\u4e3a\u4ec0\u4e48\u4e0d\u76f4\u63a5\u81ea\u52a8\u91cd\u53d1<\/h4>\n

      \u56de\u663e\u3001\u5b57\u5178\u67e5\u8be2\u901a\u5e38\u53ef\u4ee5\u91cd\u8bd5，\u4f46\u540e\u7eed\u4e1a\u52a1\u53ef\u80fd\u662f\u201c\u6263\u6b3e\u201d\u201c\u63d0\u4ea4\u4efb\u52a1\u201d\u7b49\u6709\u526f\u4f5c\u7528\u64cd\u4f5c\u3002\u54cd\u5e94\u4e22\u5931\u65f6，\u5ba2\u6237\u7aef\u91cd\u65b0\u53d1\u9001\u53ef\u80fd\u5bfc\u81f4\u91cd\u590d\u5904\u7406\u3002<\/p>\n

      \u56e0\u6b64\u8fd9\u91cc\u8ba9\u5ba2\u6237\u7aef\u62a5\u544a\u201c\u4ea4\u4ed8\u72b6\u6001\u672a\u77e5\u201d，\u4e0d\u81ea\u52a8\u91cd\u53d1\u3002\u53ef\u9760\u8bf7\u6c42\u534f\u8bae\u9700\u8981\u8bf7\u6c42\u7f16\u53f7\u3001\u8d85\u65f6\u7b56\u7565\u548c\u53bb\u91cd\u673a\u5236\u3002\u5148\u660e\u786e UDP \u7684\u8bed\u4e49，\u518d\u51b3\u5b9a\u4e1a\u52a1\u600e\u6837\u8865\u8db3\u5b83\u3002<\/p>\n

      \n

      \u516b\u3001\u5b8c\u6574\u7684\u56de\u663e\u670d\u52a1\u5668\u4e0e\u5ba2\u6237\u7aef<\/h3>\n

      \u524d\u9762\u7684\u63a5\u53e3\u8bf4\u660e\u89e3\u51b3\u4e86\u201c\u4e3a\u4ec0\u4e48\u8fd9\u6837\u5199\u201d\u3002\u8fd9\u4e00\u8282\u628a\u5b83\u4eec\u7ec4\u7ec7\u6210\u5b8c\u6574\u9879\u76ee，\u65b9\u4fbf\u5728 Linux \u4e0a\u76f4\u63a5\u7f16\u8bd1\u3002<\/p>\n

      code\/
      \n\u251c\u2500\u2500 udp.hpp # \u5730\u5740\u3001\u7aef\u53e3\u4e0e Socket \u8d44\u6e90\u5c01\u88c5
      \n\u251c\u2500\u2500 echo_server.cpp # \u539f\u6837\u56de\u663e
      \n\u251c\u2500\u2500 udp_client.cpp # \u4ea4\u4e92\u5f0f\u8bf7\u6c42\/\u54cd\u5e94\u5ba2\u6237\u7aef
      \n\u251c\u2500\u2500 Makefile
      \n\u2514\u2500\u2500 README.md<\/p>\n

      \u4ee3\u7801\u4e0d\u4f9d\u8d56 PDF \u4e2d\u7701\u7565\u7684 Log.hpp\u3001Thread.hpp \u7b49\u6587\u4ef6\u3002\u9519\u8bef\u7531\u5f02\u5e38\u643a\u5e26\u5230\u4e3b\u51fd\u6570，\u4e3b\u51fd\u6570\u7edf\u4e00\u6253\u5370\u5e76\u8fd4\u56de\u975e\u96f6\u72b6\u6001；\u8fd9\u53ea\u662f\u4e3a\u4e86\u8ba9\u7f51\u7edc\u4e3b\u7ebf\u66f4\u96c6\u4e2d，\u4e0d\u8981\u6c42\u8bfb\u8005\u5148\u642d\u5efa\u5b8c\u6574\u65e5\u5fd7\u7cfb\u7edf\u3002<\/p>\n

      8.1 \u5730\u5740\u548c\u8d44\u6e90\u5c01\u88c5：udp.hpp<\/h4>\n

      Endpoint \u4fdd\u5b58\u4e00\u4e2a IPv4 \u7aef\u70b9，\u8d1f\u8d23\u6587\u672c\u8f6c\u6362\u3001\u7aef\u53e3\u8f6c\u6362\u548c\u5730\u5740\u6bd4\u8f83；UdpSocket \u8d1f\u8d23\u521b\u5efa\u3001\u7ed1\u5b9a\u3001\u6536\u53d1\u4e0e\u5173\u95ed\u3002<\/p>\n

      #<\/span>pragma<\/span> once<\/span><\/span>
      \n#<\/span>include<\/span> <arpa\/inet.h><\/span><\/span>
      \n#<\/span>include<\/span> <sys\/socket.h><\/span><\/span>
      \n#<\/span>include<\/span> <sys\/time.h><\/span><\/span>
      \n#<\/span>include<\/span> <unistd.h><\/span><\/span>
      \n#<\/span>include<\/span> <cerrno><\/span><\/span>
      \n#<\/span>include<\/span> <cstdint><\/span><\/span>
      \n#<\/span>include<\/span> <stdexcept><\/span><\/span>
      \n#<\/span>include<\/span> <string><\/span><\/span>
      \n#<\/span>include<\/span> <system_error><\/span><\/span><\/p>\n

      inline<\/span> constexpr<\/span> std::<\/span>size_t kMaxDatagram =<\/span> 4096<\/span>;<\/span><\/p>\n

      [<\/span>[<\/span>noreturn]<\/span>]<\/span> inline<\/span> void<\/span> SystemError<\/span>(<\/span>const<\/span> char<\/span>*<\/span> operation)<\/span> {<\/span>
      \n throw<\/span> std::<\/span>system_error<\/span>(<\/span>errno,<\/span> std::<\/span>generic_category<\/span>(<\/span>)<\/span>,<\/span> operation)<\/span>;<\/span>
      \n}<\/span><\/p>\n

      inline<\/span> uint16_t<\/span> ParsePort<\/span>(<\/span>const<\/span> std::<\/span>string&<\/span> text)<\/span> {<\/span>
      \n if<\/span> (<\/span>text.<\/span>empty<\/span>(<\/span>)<\/span> ||<\/span> text.<\/span>find_first_not_of<\/span>(<\/span>"0123456789"<\/span>)<\/span> !=<\/span> std::<\/span>string::<\/span>npos)<\/span>
      \n throw<\/span> std::<\/span>invalid_argument<\/span>(<\/span>"port must contain decimal digits"<\/span>)<\/span>;<\/span>
      \n const<\/span> auto<\/span> value =<\/span> std::<\/span>stoul<\/span>(<\/span>text)<\/span>;<\/span>
      \n if<\/span> (<\/span>value ==<\/span> 0<\/span> ||<\/span> value ><\/span> 65535<\/span>)<\/span>
      \n throw<\/span> std::<\/span>out_of_range<\/span>(<\/span>"port must be in 1..65535"<\/span>)<\/span>;<\/span>
      \n return<\/span> static_cast<\/span><<\/span>uint16_t<\/span>><\/span><\/span><\/span>(<\/span>value)<\/span>;<\/span>
      \n}<\/span><\/p>\n

      class<\/span> Endpoint<\/span> {<\/span>
      \npublic<\/span>:<\/span>
      \n Endpoint<\/span>(<\/span>)<\/span> =<\/span> default<\/span>;<\/span>
      \n explicit<\/span> Endpoint<\/span>(<\/span>const<\/span> sockaddr_in&<\/span> address)<\/span> :<\/span> address_<\/span>(<\/span>address)<\/span> {<\/span>}<\/span>
      \n Endpoint<\/span>(<\/span>const<\/span> std::<\/span>string&<\/span> ip,<\/span> uint16_t<\/span> port)<\/span> {<\/span>
      \n address_.<\/span>sin_family =<\/span> AF_INET;<\/span>
      \n address_.<\/span>sin_port =<\/span> htons<\/span>(<\/span>port)<\/span>;<\/span>
      \n const<\/span> int<\/span> result =<\/span> inet_pton<\/span>(<\/span>AF_INET,<\/span> ip.<\/span>c_str<\/span>(<\/span>)<\/span>,<\/span> &<\/span>address_.<\/span>sin_addr)<\/span>;<\/span>
      \n if<\/span> (<\/span>result ==<\/span> 0<\/span>)<\/span> throw<\/span> std::<\/span>invalid_argument<\/span>(<\/span>"invalid IPv4 address"<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>result <<\/span> 0<\/span>)<\/span> SystemError<\/span>(<\/span>"inet_pton"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n const<\/span> sockaddr_in&<\/span> Address<\/span>(<\/span>)<\/span> const<\/span> {<\/span> return<\/span> address_;<\/span> }<\/span>
      \n uint16_t<\/span> Port<\/span>(<\/span>)<\/span> const<\/span> {<\/span> return<\/span> ntohs<\/span>(<\/span>address_.<\/span>sin_port)<\/span>;<\/span> }<\/span>
      \n std::<\/span>string Text<\/span>(<\/span>)<\/span> const<\/span> {<\/span>
      \n char<\/span> ip[<\/span>INET_ADDRSTRLEN]<\/span>{<\/span>}<\/span>;<\/span>
      \n if<\/span> (<\/span>!<\/span>inet_ntop<\/span>(<\/span>AF_INET,<\/span> &<\/span>address_.<\/span>sin_addr,<\/span> ip,<\/span> sizeof<\/span>(<\/span>ip)<\/span>)<\/span>)<\/span>
      \n SystemError<\/span>(<\/span>"inet_ntop"<\/span>)<\/span>;<\/span>
      \n return<\/span> std::<\/span>string<\/span>(<\/span>ip)<\/span> +<\/span> ":"<\/span> +<\/span> std::<\/span>to_string<\/span>(<\/span>Port<\/span>(<\/span>)<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n bool<\/span> operator<\/span>==<\/span>(<\/span>const<\/span> Endpoint&<\/span> other)<\/span> const<\/span> {<\/span>
      \n return<\/span> address_.<\/span>sin_family ==<\/span> other.<\/span>address_.<\/span>sin_family &&<\/span>
      \n address_.<\/span>sin_port ==<\/span> other.<\/span>address_.<\/span>sin_port &&<\/span>
      \n address_.<\/span>sin_addr.<\/span>s_addr ==<\/span> other.<\/span>address_.<\/span>sin_addr.<\/span>s_addr;<\/span>
      \n }<\/span>
      \nprivate<\/span>:<\/span>
      \n sockaddr_in address_{<\/span>}<\/span>;<\/span>
      \n}<\/span>;<\/span><\/p>\n

      class<\/span> UdpSocket<\/span> {<\/span>
      \npublic<\/span>:<\/span>
      \n UdpSocket<\/span>(<\/span>)<\/span> :<\/span> fd_<\/span>(<\/span>socket<\/span>(<\/span>AF_INET,<\/span> SOCK_DGRAM,<\/span> 0<\/span>)<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>fd_ <<\/span> 0<\/span>)<\/span> SystemError<\/span>(<\/span>"socket"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n ~<\/span>UdpSocket<\/span>(<\/span>)<\/span> {<\/span> if<\/span> (<\/span>fd_ >=<\/span> 0<\/span>)<\/span> ::<\/span>close<\/span>(<\/span>fd_)<\/span>;<\/span> }<\/span>
      \n UdpSocket<\/span>(<\/span>const<\/span> UdpSocket&<\/span>)<\/span> =<\/span> delete<\/span>;<\/span>
      \n UdpSocket&<\/span> operator<\/span>=<\/span>(<\/span>const<\/span> UdpSocket&<\/span>)<\/span> =<\/span> delete<\/span>;<\/span><\/p>\n

      void<\/span> BindAny<\/span>(<\/span>uint16_t<\/span> port)<\/span> {<\/span>
      \n sockaddr_in local{<\/span>}<\/span>;<\/span>
      \n local.<\/span>sin_family =<\/span> AF_INET;<\/span>
      \n local.<\/span>sin_port =<\/span> htons<\/span>(<\/span>port)<\/span>;<\/span>
      \n local.<\/span>sin_addr.<\/span>s_addr =<\/span> htonl<\/span>(<\/span>INADDR_ANY)<\/span>;<\/span>
      \n if<\/span> (<\/span>::<\/span>bind<\/span>(<\/span>fd_,<\/span> reinterpret_cast<\/span><<\/span>const<\/span> sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>local)<\/span>,<\/span> sizeof<\/span>(<\/span>local)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span>
      \n SystemError<\/span>(<\/span>"bind"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n Endpoint Local<\/span>(<\/span>)<\/span> const<\/span> {<\/span>
      \n sockaddr_in local{<\/span>}<\/span>;<\/span>
      \n socklen_t length =<\/span> sizeof<\/span>(<\/span>local)<\/span>;<\/span>
      \n if<\/span> (<\/span>getsockname<\/span>(<\/span>fd_,<\/span> reinterpret_cast<\/span><<\/span>sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>local)<\/span>,<\/span> &<\/span>length)<\/span> <<\/span> 0<\/span>)<\/span>
      \n SystemError<\/span>(<\/span>"getsockname"<\/span>)<\/span>;<\/span>
      \n return<\/span> Endpoint<\/span>(<\/span>local)<\/span>;<\/span>
      \n }<\/span>
      \n void<\/span> ReceiveTimeout<\/span>(<\/span>int<\/span> milliseconds)<\/span> {<\/span>
      \n if<\/span> (<\/span>milliseconds <<\/span> 0<\/span>)<\/span> throw<\/span> std::<\/span>invalid_argument<\/span>(<\/span>"negative timeout"<\/span>)<\/span>;<\/span>
      \n timeval timeout{<\/span>}<\/span>;<\/span>
      \n timeout.<\/span>tv_sec =<\/span> milliseconds \/<\/span> 1000<\/span>;<\/span>
      \n timeout.<\/span>tv_usec =<\/span> (<\/span>milliseconds %<\/span> 1000<\/span>)<\/span> *<\/span> 1000<\/span>;<\/span>
      \n if<\/span> (<\/span>setsockopt<\/span>(<\/span>fd_,<\/span> SOL_SOCKET,<\/span> SO_RCVTIMEO,<\/span> &<\/span>timeout,<\/span> sizeof<\/span>(<\/span>timeout)<\/span>)<\/span> <<\/span> 0<\/span>)<\/span>
      \n SystemError<\/span>(<\/span>"setsockopt"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n void<\/span> SendTo<\/span>(<\/span>const<\/span> std::<\/span>string&<\/span> message,<\/span> const<\/span> Endpoint&<\/span> peer)<\/span> const<\/span> {<\/span>
      \n if<\/span> (<\/span>message.<\/span>size<\/span>(<\/span>)<\/span> ><\/span> kMaxDatagram)<\/span>
      \n throw<\/span> std::<\/span>length_error<\/span>(<\/span>"datagram exceeds 4096-byte demo limit"<\/span>)<\/span>;<\/span>
      \n ssize_t n;<\/span>
      \n do<\/span> {<\/span>
      \n n =<\/span> sendto<\/span>(<\/span>fd_,<\/span> message.<\/span>data<\/span>(<\/span>)<\/span>,<\/span> message.<\/span>size<\/span>(<\/span>)<\/span>,<\/span> 0<\/span>,<\/span>
      \n reinterpret_cast<\/span><<\/span>const<\/span> sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>peer.<\/span>Address<\/span>(<\/span>)<\/span>)<\/span>,<\/span> sizeof<\/span>(<\/span>sockaddr_in)<\/span>)<\/span>;<\/span>
      \n }<\/span> while<\/span> (<\/span>n <<\/span> 0<\/span> &&<\/span> errno ==<\/span> EINTR)<\/span>;<\/span>
      \n if<\/span> (<\/span>n <<\/span> 0<\/span>)<\/span> SystemError<\/span>(<\/span>"sendto"<\/span>)<\/span>;<\/span>
      \n if<\/span> (<\/span>static_cast<\/span><<\/span>std::<\/span>size_t><\/span><\/span><\/span>(<\/span>n)<\/span> !=<\/span> message.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>
      \n throw<\/span> std::<\/span>runtime_error<\/span>(<\/span>"incomplete datagram send"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n \/\/ false means receive timeout; an empty datagram still returns true.<\/span>
      \n bool<\/span> Receive<\/span>(<\/span>std::<\/span>string&<\/span> message,<\/span> Endpoint&<\/span> peer)<\/span> const<\/span> {<\/span>
      \n char<\/span> buffer[<\/span>kMaxDatagram]<\/span>;<\/span>
      \n sockaddr_in address{<\/span>}<\/span>;<\/span>
      \n ssize_t n;<\/span>
      \n do<\/span> {<\/span>
      \n socklen_t length =<\/span> sizeof<\/span>(<\/span>address)<\/span>;<\/span>
      \n n =<\/span> recvfrom<\/span>(<\/span>fd_,<\/span> buffer,<\/span> sizeof<\/span>(<\/span>buffer)<\/span>,<\/span> MSG_TRUNC,<\/span>
      \n reinterpret_cast<\/span><<\/span>sockaddr*<\/span>><\/span><\/span><\/span>(<\/span>&<\/span>address)<\/span>,<\/span> &<\/span>length)<\/span>;<\/span>
      \n }<\/span> while<\/span> (<\/span>n <<\/span> 0<\/span> &&<\/span> errno ==<\/span> EINTR)<\/span>;<\/span>
      \n if<\/span> (<\/span>n <<\/span> 0<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>errno ==<\/span> EAGAIN ||<\/span> errno ==<\/span> EWOULDBLOCK)<\/span> return<\/span> false<\/span>;<\/span>
      \n SystemError<\/span>(<\/span>"recvfrom"<\/span>)<\/span>;<\/span>
      \n }<\/span>
      \n if<\/span> (<\/span>static_cast<\/span><<\/span>std::<\/span>size_t><\/span><\/span><\/span>(<\/span>n)<\/span> ><\/span> sizeof<\/span>(<\/span>buffer)<\/span>)<\/span>
      \n throw<\/span> std::<\/span>length_error<\/span>(<\/span>"oversized datagram discarded"<\/span>)<\/span>;<\/span>
      \n message.<\/span>assign<\/span>(<\/span>buffer,<\/span> static_cast<\/span><<\/span>std::<\/span>size_t><\/span><\/span><\/span>(<\/span>n)<\/span>)<\/span>;<\/span>
      \n peer =<\/span> Endpoint<\/span>(<\/span>address)<\/span>;<\/span>
      \n return<\/span> true<\/span>;<\/span>
      \n }<\/span>
      \nprivate<\/span>:<\/span>
      \n int<\/span> fd_;<\/span>
      \n}<\/span>;<\/span><\/p>\n

      \u8fd9\u4efd\u5934\u6587\u4ef6\u6709\u4e94\u4e2a\u503c\u5f97\u5355\u72ec\u5f3a\u8c03\u7684\u7ec6\u8282：<\/p>\n

    • ParsePort \u5728\u8f6c\u6210 uint16_t \u4e4b\u524d\u68c0\u67e5\u8303\u56f4，\u9632\u6b62 70000 \u88ab\u622a\u6210\u53e6\u4e00\u4e2a\u6570\u503c；<\/li>\n
    • \u6790\u6784\u51fd\u6570\u5173\u95ed\u6709\u6548\u63cf\u8ff0\u7b26，\u590d\u5236\u64cd\u4f5c\u88ab\u7981\u7528；<\/li>\n
    • SendTo \u7528\u663e\u5f0f\u5b57\u8282\u957f\u5ea6，\u5408\u6cd5\u7a7a\u6d88\u606f\u7684\u53d1\u9001\u7ed3\u679c 0 \u4e5f\u80fd\u901a\u8fc7\u68c0\u67e5；<\/li>\n
    • Receive \u5148\u5904\u7406 EINTR \u548c\u8d85\u65f6，\u518d\u68c0\u67e5\u622a\u65ad，\u6700\u540e\u624d\u590d\u5236\u7f13\u51b2\u533a；<\/li>\n
    • ReceiveTimeout(0) \u5bf9\u5e94\u4e0d\u542f\u7528\u63a5\u6536\u8d85\u65f6，\u975e\u96f6\u503c\u7528\u4e8e\u5ba2\u6237\u7aef\u7b49\u5f85\u8fb9\u754c\u3002<\/li>\n

      \u672c\u6587\u4e0d\u4e3a close \u5728 EINTR \u540e\u76f2\u76ee\u91cd\u8bd5，\u4e5f\u4e0d\u5728\u6790\u6784\u51fd\u6570\u91cc\u629b\u5f02\u5e38\u3002\u5173\u95ed\u8d44\u6e90\u6709\u81ea\u5df1\u7684\u5e73\u53f0\u8bed\u4e49，\u4e0d\u80fd\u7b80\u5355\u7167\u642c\u53d1\u9001\u3001\u63a5\u6536\u7684\u91cd\u8bd5\u65b9\u5f0f\u3002<\/p>\n

      8.2 \u670d\u52a1\u7aef：echo_server.cpp<\/h4>\n

      \u670d\u52a1\u5668\u53ea\u505a\u4e09\u4ef6\u4e8b：\u7ed1\u5b9a\u7aef\u53e3\u3001\u63a5\u6536\u8bf7\u6c42\u3001\u628a\u539f\u59cb\u5185\u5bb9\u53d1\u56de\u539f\u59cb\u6765\u6e90\u3002<\/p>\n

      #<\/span>include<\/span> "udp.hpp"<\/span><\/span>
      \n#<\/span>include<\/span> <iostream><\/span><\/span><\/p>\n

      int<\/span> main<\/span>(<\/span>int<\/span> argc,<\/span> char<\/span>*<\/span> argv[<\/span>]<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>argc !=<\/span> 2<\/span>)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> "Usage: "<\/span> <<<\/span> argv[<\/span>0<\/span>]<\/span> <<<\/span> " <port>\\\\n"<\/span>;<\/span>
      \n return<\/span> 1<\/span>;<\/span>
      \n }<\/span>
      \n try<\/span> {<\/span>
      \n UdpSocket socket;<\/span>
      \n socket.<\/span>BindAny<\/span>(<\/span>ParsePort<\/span>(<\/span>argv[<\/span>1<\/span>]<\/span>)<\/span>)<\/span>;<\/span>
      \n std::<\/span>cout <<<\/span> "echo listening at "<\/span> <<<\/span> socket.<\/span>Local<\/span>(<\/span>)<\/span>.<\/span>Text<\/span>(<\/span>)<\/span> <<<\/span> std::<\/span>endl;<\/span>
      \n for<\/span> (<\/span>;<\/span>;<\/span>)<\/span> {<\/span>
      \n std::<\/span>string request;<\/span>
      \n Endpoint peer;<\/span>
      \n try<\/span> {<\/span>
      \n if<\/span> (<\/span>!<\/span>socket.<\/span>Receive<\/span>(<\/span>request,<\/span> peer)<\/span>)<\/span> continue<\/span>;<\/span>
      \n }<\/span> catch<\/span> (<\/span>const<\/span> std::<\/span>length_error&<\/span> error)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> error.<\/span>what<\/span>(<\/span>)<\/span> <<<\/span> '\\\\n'<\/span>;<\/span>
      \n continue<\/span>;<\/span>
      \n }<\/span>
      \n std::<\/span>cout <<<\/span> '['<\/span> <<<\/span> peer.<\/span>Text<\/span>(<\/span>)<\/span> <<<\/span> "] bytes="<\/span> <<<\/span> request.<\/span>size<\/span>(<\/span>)<\/span>
      \n <<<\/span> " request="<\/span> <<<\/span> request <<<\/span> std::<\/span>endl;<\/span>
      \n socket.<\/span>SendTo<\/span>(<\/span>request,<\/span> peer)<\/span>;<\/span>
      \n }<\/span>
      \n }<\/span> catch<\/span> (<\/span>const<\/span> std::<\/span>exception&<\/span> error)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> error.<\/span>what<\/span>(<\/span>)<\/span> <<<\/span> '\\\\n'<\/span>;<\/span>
      \n return<\/span> 2<\/span>;<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      peer \u6bcf\u4e00\u8f6e\u90fd\u4f1a\u66f4\u65b0\u3002\u56e0\u6b64，\u4e0d\u7ba1\u8fd9\u6761\u6d88\u606f\u6765\u81ea\u5ba2\u6237\u7aef A \u8fd8\u662f B，\u90fd\u80fd\u591f\u56de\u7ed9\u672c\u6b21\u53d1\u9001\u8005\u3002\u8fd9\u91cc\u4e0d\u7ef4\u62a4\u201c\u8fde\u63a5\u8868\u201d，\u4e5f\u4e0d\u5728\u7b2c\u4e00\u6b21\u63a5\u6536\u540e\u6c38\u4e45\u8bb0\u4f4f\u67d0\u4e2a\u5ba2\u6237\u7aef\u3002<\/p>\n

      \u63a5\u6536\u5230\u8d85\u8fc7\u5e94\u7528\u7f13\u51b2\u533a\u7684\u6570\u636e\u62a5\u65f6，\u670d\u52a1\u5668\u4e22\u5f03\u8fd9\u6761\u6d88\u606f\u5e76\u7ee7\u7eed\u63a5\u6536\u3002\u5176\u4ed6\u5f02\u5e38\u4f1a\u7ec8\u6b62\u8fd9\u4e2a\u6559\u5b66\u7a0b\u5e8f；\u751f\u4ea7\u670d\u52a1\u901a\u5e38\u8fd8\u9700\u8981\u6309\u9519\u8bef\u7c7b\u522b\u533a\u5206\u662f\u5426\u7ee7\u7eed\u3001\u9000\u907f\u6216\u9000\u51fa\u3002<\/p>\n

      8.3 \u5ba2\u6237\u7aef：udp_client.cpp<\/h4>\n

      \u5ba2\u6237\u7aef\u4ee5\u201c\u4e00\u884c\u8f93\u5165\u5bf9\u5e94\u4e00\u6b21\u8bf7\u6c42\u201d\u7684\u65b9\u5f0f\u5de5\u4f5c\u3002\u5148\u53d1\u9001，\u518d\u7b49\u5f85\u670d\u52a1\u5668\u54cd\u5e94\u3002<\/p>\n

      #<\/span>include<\/span> "udp.hpp"<\/span><\/span>
      \n#<\/span>include<\/span> <iostream><\/span><\/span><\/p>\n

      int<\/span> main<\/span>(<\/span>int<\/span> argc,<\/span> char<\/span>*<\/span> argv[<\/span>]<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>argc !=<\/span> 3<\/span>)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> "Usage: "<\/span> <<<\/span> argv[<\/span>0<\/span>]<\/span> <<<\/span> " <server-ip> <port>\\\\n"<\/span>;<\/span>
      \n return<\/span> 1<\/span>;<\/span>
      \n }<\/span>
      \n try<\/span> {<\/span>
      \n Endpoint server<\/span>(<\/span>argv[<\/span>1<\/span>]<\/span>,<\/span> ParsePort<\/span>(<\/span>argv[<\/span>2<\/span>]<\/span>)<\/span>)<\/span>;<\/span>
      \n UdpSocket socket;<\/span>
      \n socket.<\/span>ReceiveTimeout<\/span>(<\/span>3000<\/span>)<\/span>;<\/span>
      \n std::<\/span>string request;<\/span>
      \n while<\/span> (<\/span>std::<\/span>cout <<<\/span> "request (\/quit exits)> "<\/span> &&<\/span> std::<\/span>getline<\/span>(<\/span>std::<\/span>cin,<\/span> request)<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>request ==<\/span> "\/quit"<\/span>)<\/span> break<\/span>;<\/span>
      \n if<\/span> (<\/span>request.<\/span>size<\/span>(<\/span>)<\/span> ><\/span> 1024<\/span>)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> "request exceeds 1024 bytes\\\\n"<\/span>;<\/span>
      \n continue<\/span>;<\/span>
      \n }<\/span>
      \n socket.<\/span>SendTo<\/span>(<\/span>request,<\/span> server)<\/span>;<\/span>
      \n std::<\/span>cout <<<\/span> "local endpoint: "<\/span> <<<\/span> socket.<\/span>Local<\/span>(<\/span>)<\/span>.<\/span>Text<\/span>(<\/span>)<\/span> <<<\/span> '\\\\n'<\/span>;<\/span>
      \n std::<\/span>string response;<\/span>
      \n Endpoint peer;<\/span>
      \n bool<\/span> received =<\/span> false<\/span>;<\/span>
      \n while<\/span> (<\/span>socket.<\/span>Receive<\/span>(<\/span>response,<\/span> peer)<\/span>)<\/span> {<\/span>
      \n if<\/span> (<\/span>peer ==<\/span> server)<\/span> {<\/span> received =<\/span> true<\/span>;<\/span> break<\/span>;<\/span> }<\/span>
      \n }<\/span>
      \n if<\/span> (<\/span>received)<\/span> std::<\/span>cout <<<\/span> "response ["<\/span> <<<\/span> response.<\/span>size<\/span>(<\/span>)<\/span> <<<\/span> "]: "<\/span> <<<\/span> response <<<\/span> '\\\\n'<\/span>;<\/span>
      \n else<\/span> std::<\/span>cout <<<\/span> "receive timeout; delivery is unknown\\\\n"<\/span>;<\/span>
      \n }<\/span>
      \n }<\/span> catch<\/span> (<\/span>const<\/span> std::<\/span>exception&<\/span> error)<\/span> {<\/span>
      \n std::<\/span>cerr <<<\/span> error.<\/span>what<\/span>(<\/span>)<\/span> <<<\/span> '\\\\n'<\/span>;<\/span>
      \n return<\/span> 2<\/span>;<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      \u5b83\u6709\u610f\u4fdd\u7559\u4e86\u51e0\u4e2a\u4fbf\u4e8e\u89c2\u5bdf\u7684\u884c\u4e3a：<\/p>\n

        \n
      • \u7b2c\u4e00\u6761\u6d88\u606f\u53d1\u51fa\u540e\u6253\u5370\u672c\u5730\u7aef\u70b9，\u89c2\u5bdf\u7cfb\u7edf\u5206\u914d\u7684\u7aef\u53e3；<\/li>\n
      • \u7a7a\u884c\u4e5f\u4f1a\u53d1\u51fa\u4e00\u4e2a\u96f6\u957f\u5ea6\u6570\u636e\u62a5；<\/li>\n
      • \/quit \u662f\u5ba2\u6237\u7aef\u672c\u5730\u9000\u51fa\u547d\u4ee4，\u4e0d\u4f1a\u53d1\u9001\u5230\u56de\u663e\u670d\u52a1\u5668；<\/li>\n
      • \u53ea\u63a5\u53d7\u6765\u81ea\u914d\u7f6e\u7684\u670d\u52a1\u5668\u7aef\u70b9\u7684\u54cd\u5e94；<\/li>\n
      • \u4e09\u79d2\u5185\u6ca1\u6709\u7b49\u5230\u54cd\u5e94\u65f6\u62a5\u544a\u8d85\u65f6，\u5e76\u5141\u8bb8\u7ee7\u7eed\u8f93\u5165\u3002<\/li>\n<\/ul>\n

        \u6765\u6e90\u6bd4\u8f83\u53ef\u4ee5\u8fc7\u6ee4\u666e\u901a\u7684\u65e0\u5173\u6570\u636e\u62a5，\u4f46\u5b83\u4e0d\u662f\u8eab\u4efd\u8ba4\u8bc1\u3002\u672c\u6587\u662f\u53d7\u63a7\u5b9e\u9a8c\u4e2d\u7684\u6559\u5b66\u5ba2\u6237\u7aef，\u4e0d\u63d0\u4f9b\u9762\u5411\u516c\u7f51\u7684\u53ef\u4fe1\u901a\u4fe1\u534f\u8bae\u3002<\/p>\n

        \u8fd8\u6709\u4e00\u4e2a\u534f\u8bae\u5c42\u9762\u7684\u5c40\u9650：\u5982\u679c\u4e0a\u4e00\u6761\u8bf7\u6c42\u7684\u54cd\u5e94\u8fdf\u5230，\u5b83\u53ef\u80fd\u88ab\u4e0b\u4e00\u6b21\u7b49\u5f85\u8bfb\u5230\u3002\u8fd9\u4e2a\u5ba2\u6237\u7aef\u6ca1\u6709\u8bf7\u6c42\u7f16\u53f7，\u56e0\u6b64\u53ea\u9002\u5408\u6309\u987a\u5e8f\u8fdb\u884c\u7b80\u5355\u5b9e\u9a8c；\u589e\u52a0\u8bf7\u6c42 ID \u548c\u603b\u7b49\u5f85\u622a\u6b62\u65f6\u95f4，\u662f\u8fdb\u4e00\u6b65\u5b8c\u5584\u8bf7\u6c42\/\u54cd\u5e94\u534f\u8bae\u7684\u65b9\u5411\u3002<\/p>\n

        \n

        \u4e5d\u3001\u7f16\u8bd1\u8fd0\u884c\u4e0e\u9a8c\u8bc1\u65b9\u6cd5<\/h3>\n

        9.1 \u5728 Linux \u4e2d\u7f16\u8bd1<\/h4>\n

        \u8fdb\u5165\u672c\u7bc7\u6587\u7ae0\u7684 code \u6587\u4ef6\u5939：<\/p>\n

        make<\/span><\/p>\n

        \u4e5f\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528 g++：<\/p>\n

        g++ -std<\/span>=<\/span>c++17 -Wall<\/span> -Wextra<\/span> -Wpedantic<\/span> -O2<\/span> echo_server.cpp -o<\/span> echo_server
        \ng++ -std<\/span>=<\/span>c++17 -Wall<\/span> -Wextra<\/span> -Wpedantic<\/span> -O2<\/span> udp_client.cpp -o<\/span> udp_client<\/p>\n

        \u8fd9\u91cc\u662f Linux\/POSIX \u4ee3\u7801，\u4e0d\u80fd\u628a\u5b83\u76f4\u63a5\u5f53\u6210 Windows Winsock \u7a0b\u5e8f\u7f16\u8bd1\u3002Windows \u8bbf\u95ee Linux \u7684\u52a0\u9910 PDF \u5c5e\u4e8e\u540e\u7eed\u72ec\u7acb\u6587\u7ae0，\u672c\u7bc7\u4e0d\u63d0\u524d\u6df7\u5165\u5b83\u7684\u5185\u5bb9\u3002<\/p>\n

        9.2 \u4e24\u4e2a\u7ec8\u7aef\u8dd1\u901a\u56de\u663e<\/h4>\n

        \u7ec8\u7aef A：<\/p>\n

        .\/echo_server 8888<\/span><\/p>\n

        \u7ec8\u7aef B：<\/p>\n

        .\/udp_client 127.0<\/span>.0.1 8888<\/span><\/p>\n

        \u8f93\u5165 hello，\u5ba2\u6237\u7aef\u4f1a\u663e\u793a\u957f\u5ea6\u4e3a 5 \u7684\u54cd\u5e94\u3002\u8f93\u5165 \u4f60\u597d，UDP，\u5ba2\u6237\u7aef\u5e94\u6536\u5230\u540c\u6837\u7684\u6587\u672c\u3002\u8fd9\u91cc\u7684\u957f\u5ea6\u662f\u5b57\u8282\u6570，\u4e0d\u662f\u6c49\u5b57\u6570\u91cf，UTF-8 \u4e2d\u6587\u901a\u5e38\u5360\u7528\u591a\u4e2a\u5b57\u8282\u3002<\/p>\n

        \u518d\u8f93\u5165\u4e00\u4e2a\u7a7a\u884c，\u54cd\u5e94\u957f\u5ea6\u5e94\u4e3a 0，\u4f46\u5ba2\u6237\u7aef\u4e0d\u4f1a\u9000\u51fa\u3002\u8fd9\u6b63\u597d\u9a8c\u8bc1\u524d\u9762\u8bb2\u5230\u7684\u7a7a\u6570\u636e\u62a5\u8bed\u4e49\u3002<\/p>\n

        \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n

        9.3 \u7528 Python \u68c0\u67e5\u4e8c\u8fdb\u5236\u6570\u636e<\/h4>\n

        \u4fdd\u6301\u670d\u52a1\u5668\u8fd0\u884c，\u5728\u7b2c\u4e09\u4e2a\u7ec8\u7aef\u6267\u884c：<\/p>\n

        python3 – <<<\/span>'PY'
        \nimport socket
        \ns = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        \ns.settimeout(2)
        \nfor data in (b'hello', '\u4f60\u597d，UDP'.encode(), b'', b'A\\\\x00B'):
        \n s.sendto(data, ('127.0.0.1', 8888))
        \n result, peer = s.recvfrom(4096)
        \n assert result == data, (data, result)
        \n print('OK:', repr(result), peer)
        \ns.close()
        \nPY<\/span><\/p>\n

        \u8fd9\u6bd4\u53ea\u770b\u7ec8\u7aef\u8f93\u51fa\u66f4\u53ef\u9760：\u5b83\u9010\u5b57\u8282\u6bd4\u8f83\u7ed3\u679c，\u53ef\u4ee5\u53d1\u73b0 strlen \u5bfc\u81f4\u7684\u5185\u90e8\u96f6\u5b57\u8282\u622a\u65ad，\u4e5f\u53ef\u4ee5\u786e\u8ba4\u7a7a\u5305\u786e\u5b9e\u6709\u54cd\u5e94\u3002<\/p>\n

        9.4 \u9a8c\u8bc1\u8d85\u957f\u6d88\u606f<\/h4>\n

        \u5411\u670d\u52a1\u5668\u53d1\u9001 4097 \u5b57\u8282，\u9884\u671f\u4e0d\u4f1a\u5f97\u5230\u622a\u65ad\u540e\u7684\u56de\u663e，\u800c\u662f\u7531\u670d\u52a1\u5668\u4e22\u5f03\u3002\u7d27\u63a5\u7740\u518d\u53d1\u4e00\u6761\u6b63\u5e38\u6d88\u606f，\u9884\u671f\u53ef\u4ee5\u7ee7\u7eed\u5904\u7406\u3002<\/p>\n

        s.<\/span>sendto(<\/span>b'x'<\/span> *<\/span> 4097<\/span>,<\/span> (<\/span>'127.0.0.1'<\/span>,<\/span> 8888<\/span>)<\/span>)<\/span>
        \n# \u672c\u6b21\u6ca1\u6709\u4e1a\u52a1\u54cd\u5e94；\u6309\u8bbe\u5b9a\u7684\u8d85\u65f6\u7ed3\u675f\u7b49\u5f85\u3002<\/span><\/p>\n

        \u8fd9\u4e2a\u5b9e\u9a8c\u9a8c\u8bc1\u7684\u662f\u5e94\u7528\u5c42\u957f\u5ea6\u9632\u62a4，\u4e0d\u662f\u201cUDP \u4e0d\u5141\u8bb8\u53d1\u9001 4097 \u5b57\u8282\u201d\u3002\u5728\u5b9e\u9645\u7f51\u7edc\u4e2d，\u53d1\u9001\u662f\u5426\u6210\u529f\u8fd8\u53d6\u51b3\u4e8e\u8def\u5f84\u7b49\u6761\u4ef6\u3002<\/p>\n

        9.5 \u591a\u5ba2\u6237\u7aef\u5982\u4f55\u533a\u5206<\/h4>\n

        \u540c\u65f6\u6253\u5f00\u4e24\u4e2a\u5ba2\u6237\u7aef\u3002\u670d\u52a1\u5668\u65e5\u5fd7\u4e2d\u53ef\u4ee5\u770b\u5230\u76f8\u540c\u56de\u73af IP \u642d\u914d\u4e0d\u540c\u7684\u6e90\u7aef\u53e3，\u54cd\u5e94\u4ecd\u5404\u81ea\u56de\u5230\u5bf9\u5e94\u5ba2\u6237\u7aef\u3002<\/p>\n

        \u6b64\u65f6\u53ef\u4ee5\u91cd\u65b0\u5ba1\u89c6 recvfrom：\u5b83\u4e0d\u4ec5\u7ed9\u4e86\u6d88\u606f\u5185\u5bb9，\u8fd8\u7ed9\u4e86\u670d\u52a1\u5668\u5b8c\u6210\u56de\u590d\u6240\u9700\u7684\u201c\u56de\u90ae\u5730\u5740\u201d\u3002<\/p>\n

        9.6 \u672c\u7bc7\u9a8c\u8bc1\u8303\u56f4<\/h4>\n

        \u9879\u76ee\u6574\u7406\u540e\u5728 Ubuntu 24.04 \u7684 g++ \u73af\u5883\u4e2d\u7f16\u8bd1，\u5e76\u901a\u8fc7\u56de\u73af\u901a\u4fe1\u68c0\u67e5\u666e\u901a\u6587\u672c\u3001UTF-8 \u4e2d\u6587\u3001\u7a7a\u6570\u636e\u62a5\u3001\u5185\u90e8\u96f6\u5b57\u8282\u3001\u8d85\u957f\u6570\u636e\u62a5\u4e22\u5f03\u540e\u7684\u7ee7\u7eed\u670d\u52a1，\u4ee5\u53ca\u975e\u6cd5\u5730\u5740\u548c\u7aef\u53e3\u8f93\u5165\u3002\u5177\u4f53\u9a8c\u8bc1\u8bb0\u5f55\u653e\u5728 code\/\u9a8c\u8bc1\u8bb0\u5f55.md\u3002<\/p>\n

        \u8fd9\u4e9b\u7ed3\u679c\u8bc1\u660e\u793a\u4f8b\u5728\u672c\u5730\u5b9e\u9a8c\u73af\u5883\u4e0b\u7684\u884c\u4e3a，\u4e0d\u4ee3\u8868\u5df2\u7ecf\u6d4b\u8bd5\u8fc7\u516c\u7f51\u4e22\u5305\u3001NAT\u3001\u4e91\u5b89\u5168\u7ec4\u6216\u4e0d\u540c\u53d1\u884c\u7248\u7684\u6240\u6709\u7ec6\u8282\u3002<\/p>\n

        \n

        \u5341\u3001\u5e38\u89c1\u9519\u8bef\u4e0e\u6392\u67e5\u987a\u5e8f<\/h3>\n

        \u201c\u5ba2\u6237\u7aef\u6ca1\u6536\u5230\u54cd\u5e94\u201d\u5e76\u4e0d\u80fd\u76f4\u63a5\u8bf4\u660e recvfrom \u5199\u9519\u4e86\u3002\u5148\u5224\u65ad\u7a0b\u5e8f\u505c\u5728\u54ea\u4e00\u6b65，\u518d\u68c0\u67e5\u5bf9\u5e94\u6761\u4ef6\u3002<\/p>\n

        \"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n\n\u73b0\u8c61\u4f18\u5148\u68c0\u67e5\u539f\u56e0\u4e0e\u5904\u7406<\/tr>\n\n\n\n\n\n\n\n\n\n
        socket \u5931\u8d25<\/td>\nerrno\u3001\u8d44\u6e90\u9650\u5236<\/td>\n\u5148\u770b\u9519\u8bef\u4fe1\u606f，\u4e0d\u80fd\u7ee7\u7eed\u4f7f\u7528\u65e0\u6548 fd<\/td>\n<\/tr>\n
        bind \u62a5\u5730\u5740\u4e0d\u53ef\u7528<\/td>\n\u5730\u5740\u662f\u5426\u5c5e\u4e8e\u672c\u673a<\/td>\n\u4e0d\u8981\u628a\u5bf9\u7aef IP \u6216\u6620\u5c04\u516c\u7f51 IP \u76f4\u63a5\u5f53\u672c\u5730\u5730\u5740<\/td>\n<\/tr>\n
        bind \u62a5\u5730\u5740\u5df2\u5360\u7528<\/td>\n\u662f\u5426\u5df2\u6709\u540c\u7c7b\u670d\u52a1<\/td>\n\u505c\u6b62\u65e7\u670d\u52a1，\u6216\u9009\u62e9\u5176\u4ed6\u7aef\u53e3<\/td>\n<\/tr>\n
        \u672c\u673a\u6210\u529f，\u8de8\u673a\u5668\u5931\u8d25<\/td>\n\u76ee\u6807\u5730\u5740\u3001UDP \u89c4\u5219\u3001\u8def\u7531<\/td>\n127.0.0.1 \u6c38\u8fdc\u6307\u5411\u5f53\u524d\u8fd9\u53f0\u673a\u5668<\/td>\n<\/tr>\n
        \u5730\u5740\u6b63\u786e\u4f46\u7aef\u53e3\u9519\u4e71<\/td>\nhtons \/ ntohs<\/td>\n\u8f6c\u6362\u5e94\u53d1\u751f\u5728\u4e3b\u673a\u5e8f\u4e0e\u7f51\u7edc\u5e8f\u8fb9\u754c<\/td>\n<\/tr>\n
        \u6d88\u606f\u4e2d\u9014\u88ab\u622a\u65ad<\/td>\n\u6536\u5305\u5bb9\u91cf\u3001strlen<\/td>\n\u533a\u5206\u6570\u636e\u62a5\u622a\u65ad\u4e0e C \u5b57\u7b26\u4e32\u622a\u65ad<\/td>\n<\/tr>\n
        \u7a7a\u884c\u540e\u7a0b\u5e8f\u5f02\u5e38<\/td>\n\u662f\u5426\u7528\u4e86 n <= 0<\/td>\n\u96f6\u957f\u5ea6 UDP \u6d88\u606f\u4e5f\u662f\u5408\u6cd5\u6570\u636e\u62a5<\/td>\n<\/tr>\n
        \u67e5\u8be2\u4e00\u76f4\u7b49\u5f85<\/td>\n\u662f\u5426\u8bbe\u7f6e\u8d85\u65f6<\/td>\nUDP \u4e0d\u4fdd\u8bc1\u8fdc\u7aef\u4e00\u5b9a\u56de\u590d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        10.1 \u5148\u7f29\u5c0f\u5230\u56de\u73af\u5b9e\u9a8c<\/h4>\n

        \u4f18\u5148\u7528\u540c\u673a 127.0.0.1 \u9a8c\u8bc1\u7a0b\u5e8f，\u518d\u6269\u5927\u5230\u5c40\u57df\u7f51，\u6700\u540e\u6d4b\u8bd5\u516c\u7f51\u3002\u8fd9\u6837\u6bcf\u4e00\u6b65\u65b0\u589e\u7684\u53d8\u91cf\u66f4\u5c11，\u6392\u67e5\u66f4\u5bb9\u6613\u5b9a\u4f4d\u3002<\/p>\n

        \u4e0d\u8981\u4e00\u5f00\u59cb\u540c\u65f6\u6539\u7aef\u53e3\u3001\u6539 IP\u3001\u5f00\u9632\u706b\u5899\u3001\u6539\u4ee3\u7801\u3002\u5982\u679c\u4e00\u53e3\u6c14\u6539\u4e86\u56db\u4e2a\u5730\u65b9，\u5373\u4f7f\u95ee\u9898\u6682\u65f6\u6d88\u5931，\u4e5f\u5f88\u96be\u77e5\u9053\u771f\u6b63\u539f\u56e0\u3002<\/p>\n

        10.2 \u5730\u5740\u68c0\u67e5\u8981\u770b\u4e09\u4e2a\u5c42\u6b21<\/h4>\n
      • \u547d\u4ee4\u884c\u91cc\u7684\u670d\u52a1\u5668 IP\u3001\u7aef\u53e3\u662f\u5426\u6b63\u786e；<\/li>\n
      • \u8fdb\u7a0b\u662f\u5426\u5b9e\u9645\u521b\u5efa\u5e76\u7ed1\u5b9a\u4e86\u5bf9\u5e94 UDP Socket；<\/li>\n
      • \u7f51\u7edc\u8def\u5f84\u662f\u5426\u5141\u8bb8\u6570\u636e\u62a5\u53cc\u5411\u5230\u8fbe\u3002<\/li>\n

        \u672c\u7bc7\u91cd\u70b9\u89e3\u51b3\u524d\u4e24\u4e2a\u5c42\u6b21\u3002\u5177\u4f53\u7f51\u7edc\u547d\u4ee4\u4e0e\u8de8 Windows \u9a8c\u8bc1，\u4f1a\u5728\u76f8\u5e94\u52a0\u9910\u6587\u7ae0\u4e2d\u5c55\u5f00\u3002<\/p>\n

        10.3 \u4e0d\u8981\u4e3a\u4e86\u8c03\u901a\u5c31\u9ed8\u8ba4\u6253\u5f00\u7aef\u53e3\u590d\u7528<\/h4>\n

        SO_REUSEADDR \/ SO_REUSEPORT \u6709\u7279\u5b9a\u7684\u590d\u7528\u8bed\u4e49\u3002\u5165\u95e8\u793a\u4f8b\u6ca1\u6709\u5f00\u542f\u5b83\u4eec，\u662f\u4e3a\u4e86\u8ba9\u91cd\u590d\u7ed1\u5b9a\u660e\u786e\u62a5\u9519，\u4e5f\u8ba9\u201c\u8c01\u5360\u7528\u4e86\u8fd9\u4e2a\u7aef\u53e3\u201d\u66f4\u5bb9\u6613\u89c2\u5bdf\u3002<\/p>\n

        \u9047\u5230\u5730\u5740\u5360\u7528\u65f6，\u5148\u627e\u5230\u73b0\u6709\u670d\u52a1，\u518d\u51b3\u5b9a\u662f\u5426\u786e\u5b9e\u9700\u8981\u590d\u7528\u3002\u590d\u7528\u4e0d\u662f\u6240\u6709 bind \u9519\u8bef\u7684\u901a\u7528\u8865\u4e01\u3002<\/p>\n

        \n

        \u603b\u7ed3<\/h3>\n

        UDP Socket \u7f16\u7a0b\u53ef\u4ee5\u6cbf\u7740\u4e00\u6761\u4e3b\u7ebf\u7406\u89e3：<\/p>\n

        \u786e\u5b9a\u901a\u4fe1\u89d2\u8272\u4e0e\u5730\u5740
        \n \u2192 socket \u521b\u5efa\u8d44\u6e90
        \n \u2192 \u670d\u52a1\u5668 bind \u7a33\u5b9a\u5165\u53e3
        \n \u2192 \u5ba2\u6237\u7aef sendto \u53d1\u8bf7\u6c42
        \n \u2192 \u670d\u52a1\u5668 recvfrom \u5f97\u5230\u6570\u636e\u548c\u6765\u6e90
        \n \u2192 \u5904\u7406\u540e sendto \u56de\u7ed9\u6765\u6e90
        \n \u2192 \u5ba2\u6237\u7aef recvfrom \u63a5\u6536\u54cd\u5e94
        \n \u2192 \u5173\u95ed\u8d44\u6e90<\/p>\n

        \u771f\u6b63\u9700\u8981\u8bb0\u4f4f\u7684\u4e0d\u662f\u51fd\u6570\u53c2\u6570\u6570\u91cf，\u800c\u662f\u6bcf\u4e2a\u53c2\u6570\u5728\u56de\u7b54\u4ec0\u4e48\u95ee\u9898：fd \u9009\u62e9\u901a\u4fe1\u8d44\u6e90，\u7f13\u51b2\u533a\u4e0e\u957f\u5ea6\u8bf4\u660e\u4f20\u8f93\u5185\u5bb9，\u5730\u5740\u8bf4\u660e\u672c\u5730\u5165\u53e3\u3001\u76ee\u6807\u7aef\u70b9\u6216\u6d88\u606f\u6765\u6e90\u3002<\/p>\n

        \u5730\u5740\u7ed3\u6784\u4e2d\u7684\u7aef\u53e3\u9700\u8981\u7f51\u7edc\u5b57\u8282\u5e8f，\u5730\u5740\u6587\u672c\u8f6c\u6362\u5fc5\u987b\u68c0\u67e5\u8fd4\u56de\u503c；UDP \u6210\u529f\u6536\u5305\u53ef\u4ee5\u5f97\u5230\u96f6\u5b57\u8282，\u6570\u636e\u62a5\u88ab\u622a\u65ad\u540e\u4e5f\u4e0d\u80fd\u50cf\u6587\u4ef6\u4e00\u6837\u7ee7\u7eed\u8bfb\u53d6\u5269\u4f59\u90e8\u5206\u3002\u7406\u89e3\u4e86\u8fd9\u4e9b\u8fb9\u754c，\u4ee3\u7801\u624d\u4e0d\u4f1a\u505c\u7559\u5728\u201c\u8f93\u5165 hello \u770b\u8d77\u6765\u80fd\u7528\u201d\u7684\u7a0b\u5ea6\u3002<\/p>\n

        \u4e0a\u7bc7\u7528\u56de\u663e\u5b8c\u6210\u4e86\u6700\u5c0f\u901a\u4fe1\u95ed\u73af\u3002\u63a5\u4e0b\u6765，\u628a\u201c\u6536\u5230\u4ec0\u4e48\u5c31\u8fd4\u56de\u4ec0\u4e48\u201d\u66ff\u6362\u6210\u771f\u6b63\u7684\u4e1a\u52a1\u903b\u8f91，\u518d\u4ece\u4e00\u4e2a\u54cd\u5e94\u6269\u5c55\u4e3a\u591a\u4e2a\u5ba2\u6237\u7aef\u7684\u6d88\u606f\u8f6c\u53d1，\u5c31\u8fdb\u5165\u4e0b\u7bc7\u7684\u7f51\u7edc\u5b57\u5178\u4e0e\u804a\u5929\u5ba4\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

        \/* MD \/ \u5bcc\u6587\u672c\u4e2d\u7684 .toc\uff08\u542b\u535a\u5ba2\u56ed\u642c\u5bb6\u7b49\u5d4c\u5957\u7ed3\u6784\uff09\uff1b.toc-box \u5728\u4fa7\u680f\uff0c\u4e0d\u53d7\u5f71\u54cd *\/#content_views .toc,\/* \u7f16\u8f91\u5668\u5e38\u5728\u76ee\u5f55\u524d\u540e\u63d2\u5165\u7a7a p\uff08:empty \u4ecd\u5360 20px\uff09\uff0c\u4e00\u5e76\u53bb\u6389\u907f\u514d\u9876\u7a7a\u9699 *\/#content_views.markdown_views > p:empty:has(+ .toc),#content_views.markdown_views > .toc + p:empty,\/* \u5bcc\u6587\u672c\u65e7\u7248\u76ee\u5f55\u6807\u8bb0 *\/#content<\/p>\n","protected":false},"author":2,"featured_media":116730,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[11820,58,43,78],"topic":[],"class_list":["post-116740","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-atomgit","tag-linux","tag-43","tag-78"],"yoast_head":"\n\u3010Linux \u7f51\u7edc\u7f16\u7a0b\u3011UDP Socket \u7f16\u7a0b\uff08\u4e0a\uff09\uff1a\u4ece\u5730\u5740\u4e0e\u5b57\u8282\u5e8f\u5230\u5b8c\u6574\u56de\u663e\u670d\u52a1\u5668 - 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