{"id":115231,"date":"2026-10-11T14:48:54","date_gmt":"2026-10-11T06:48:54","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/115231.html"},"modified":"2026-10-11T14:48:54","modified_gmt":"2026-10-11T06:48:54","slug":"30%e5%a4%a9%e9%80%9f%e9%80%9alinux-%e7%ac%ac%e4%b9%9d%e7%ab%a0linux%e7%bd%91%e7%bb%9c%e7%bc%96%e7%a8%8b","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/115231.html","title":{"rendered":"30\u5929\u901f\u901aLinux \u7b2c\u4e5d\u7ae0Linux\u7f51\u7edc\u7f16\u7a0b"},"content":{"rendered":"

\u4e00. \u8ba1\u7b97\u673a\u7f51\u7edc\u6982\u8ff0<\/h2>\n

1.1 TCP\/IP \u4e94\u5c42\u6a21\u578b<\/h3>\n\n\u5c42\u540d\u79f0\u8981\u70b9<\/tr>\n\n\n\n\n\n\n
5<\/td>\n\u5e94\u7528\u5c42<\/td>\n\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u4e92\u8054\u7f51\u7684\u89c4\u7a0b<\/td>\n<\/tr>\n
4<\/td>\n\u4f20\u8f93\u5c42<\/td>\nTCP\/UDP；\u8fdb\u7a0b\u5230\u8fdb\u7a0b\u7684\u901a\u4fe1\u3001\u6d41\u91cf\u63a7\u5236\u3001\u5dee\u9519\u63a7\u5236<\/td>\n<\/tr>\n
3<\/td>\n\u4e92\u8054\u7f51\u5c42<\/td>\nIP；\u4e0d\u53ef\u9760\u3001\u65e0\u8fde\u63a5\u3001\u5c3d\u6700\u5927\u52aa\u529b\u4ea4\u4ed8；32 \u4f4d IP \u5730\u5740<\/td>\n<\/tr>\n
2<\/td>\n\u6570\u636e\u94fe\u8def\u5c42<\/td>\n\u7ec4\u5e27\u4e0e\u4f20\u5e27（\u5e27\u662f\u4f20\u8f93\u5355\u4f4d）<\/td>\n<\/tr>\n
1<\/td>\n\u7269\u7406\u5c42<\/td>\n\u786c\u4ef6\u8bbe\u5907\u7684\u7535\u6c14\u7279\u6027\u89c4\u8303<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u6536\u53d1\u6d41\u7a0b：\u53d1\u9001\u65f6\u81ea\u4e0a\u800c\u4e0b \u63d2\u53e3\u5c42 \u2192 \u534f\u8bae\u5c42（\u52a0 TCP\/UDP \u5934 \u2192 \u52a0 IP \u5934）\u2192 \u63a5\u53e3\u5c42（\u52a0\u4ee5\u592a\u7f51\u5934）\u2192 \u7f51\u5361；\u63a5\u6536\u65f6\u53cd\u5411\u9010\u5c42\u5265\u79bb\u3002<\/p>\n

1.2 TCP vs UDP<\/h3>\n\nTCPUDP<\/tr>\n\n\n\n\n\n
\u8fde\u63a5<\/td>\n\u9762\u5411\u8fde\u63a5（\u4e09\u6b21\u63e1\u624b）<\/td>\n\u65e0\u8fde\u63a5<\/td>\n<\/tr>\n
\u53ef\u9760\u6027<\/td>\n\u53ef\u9760（\u786e\u8ba4 + \u8d85\u65f6\u91cd\u4f20 + \u6ed1\u52a8\u7a97\u53e3\u6d41\u63a7）<\/td>\n\u4e0d\u53ef\u9760，\u65e0\u6d41\u63a7\u65e0\u786e\u8ba4<\/td>\n<\/tr>\n
\u9002\u7528<\/td>\n\u4e00\u822c\u6570\u636e\u4f20\u8f93<\/td>\n\u7b80\u5355\u8bf7\u6c42-\u54cd\u5e94\u3001\u7f51\u7edc\u6761\u4ef6\u597d<\/td>\n<\/tr>\n
\u6548\u7387<\/td>\n\u6709\u8fde\u63a5\u5f00\u9500<\/td>\n\u5feb，\u4f46\u5dee\u9519\/\u6d41\u63a7\u8981\u5e94\u7528\u81ea\u5df1\u505a<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    \n
  • \u7528\u7aef\u53e3（16 \u4f4d）\u533a\u5206\u8fdb\u7a0b，\u8fde\u63a5\u7531\u7aef\u70b9 (host, port) \u6807\u8bc6；\u540c\u4e00\u53f0\u673a\u5668\u4e0a\u5404\u8fdb\u7a0b\u7aef\u53e3\u5fc5\u987b\u4e0d\u540c\u3002<\/li>\n<\/ul>\n

    1.3 C\/S \u6a21\u578b<\/h3>\n

    \u5ba2\u6237\u7aef\u8d1f\u8d23\u4e0e\u7528\u6237\u4ea4\u4e92\u5e76\u5c55\u793a\u7ed3\u679c，\u670d\u52a1\u5668\u7aef\u8d1f\u8d23\u5904\u7406\u8bf7\u6c42\u4e0e\u4e1a\u52a1\u903b\u8f91\u3001\u4e0d\u63d0\u4f9b\u754c\u9762\u3002\u672c\u7ae0\u4f8b\u5b50\u57fa\u672c\u90fd\u662f C\/S\u3002<\/p>\n

    \u4e8c. Socket \u7f16\u7a0b<\/h2>\n

    2.1 \u57fa\u672c API<\/h3>\n\n\u8c03\u7528\u8c01\u7528\u4f5c\u7528<\/tr>\n\n\n\n\n\n\n\n\n\n
    socket()<\/td>\n\u53cc\u65b9<\/td>\n\u521b\u5efa\u5957\u63a5\u5b57（\u8fd4\u56de\u6574\u578b\u63cf\u8ff0\u7b26）<\/td>\n<\/tr>\n
    bind()<\/td>\n\u670d\u52a1\u5668<\/td>\n\u7ed1\u5b9a\u5230\u672c\u673a IP + \u7aef\u53e3<\/td>\n<\/tr>\n
    listen()<\/td>\n\u670d\u52a1\u5668<\/td>\n\u8fdb\u5165\u76d1\u542c，backlog \u662f\u8bf7\u6c42\u961f\u5217\u957f\u5ea6<\/td>\n<\/tr>\n
    accept()<\/td>\n\u670d\u52a1\u5668<\/td>\n\u53d6\u51fa\u961f\u9996\u8fde\u63a5\u8bf7\u6c42，\u963b\u585e\u7b49\u5f85<\/td>\n<\/tr>\n
    connect()<\/td>\n\u5ba2\u6237\u7aef<\/td>\n\u53d1\u8d77\u8fde\u63a5（\u963b\u585e\u5230\u4e09\u6b21\u63e1\u624b\u5b8c\u6210\u6216\u8d85\u65f6）<\/td>\n<\/tr>\n
    send()\/write()<\/td>\n\u53cc\u65b9<\/td>\n\u53d1\u9001<\/td>\n<\/tr>\n
    recv()\/read()<\/td>\n\u53cc\u65b9<\/td>\n\u63a5\u6536<\/td>\n<\/tr>\n
    close()<\/td>\n\u53cc\u65b9<\/td>\n\u91ca\u653e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    socket<\/h4>\n

    int<\/span> socket<\/span>(<\/span>int<\/span> domain,<\/span> int<\/span> type,<\/span> int<\/span> protocol)<\/span>;<\/span><\/p>\n\n\u53c2\u6570\u5e38\u7528\u53d6\u503c<\/tr>\n\n\n\n\n
    domain<\/td>\nAF_INET（IPv4，\u6700\u5e38\u7528）／AF_INET6／AF_UNIX（\u672c\u673a\u8fdb\u7a0b\u95f4）<\/td>\n<\/tr>\n
    type<\/td>\nSOCK_STREAM（TCP）／SOCK_DGRAM（UDP）／SOCK_RAW（\u539f\u59cb\u5957\u63a5\u5b57）<\/td>\n<\/tr>\n
    protocol<\/td>\n\u4e00\u822c 0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    bind + \u5730\u5740\u7ed3\u6784<\/h4>\n

    int<\/span> bind<\/span>(<\/span>int<\/span> sockfd,<\/span> struct<\/span> sockaddr<\/span> *<\/span>my_addr,<\/span> int<\/span> addrlen)<\/span>;<\/span><\/p>\n

    struct<\/span> sockaddr_in<\/span> {<\/span>
    \n unsigned<\/span> short<\/span> sin_family;<\/span> \/\/ AF_INET<\/span>
    \n unsigned<\/span> short<\/span> sin_port;<\/span> \/\/ \u7aef\u53e3\u53f7（\u7f51\u7edc\u5b57\u8282\u5e8f）<\/span>
    \n struct<\/span> in_addr<\/span> sin_addr;<\/span> \/\/ IP \u5730\u5740<\/span>
    \n unsigned<\/span> char<\/span> sin_zero[<\/span>8<\/span>]<\/span>;<\/span> \/\/ \u586b 0，\u4f7f\u4e0e sockaddr \u7b49\u957f<\/span>
    \n}<\/span>;<\/span>
    \nstruct<\/span> in_addr<\/span> {<\/span> unsigned<\/span> long<\/span> s_addr;<\/span> }<\/span>;<\/span><\/p>\n

    \u4f20\u53c2\u65f6\u8981\u5f3a\u8f6c\u6210 (struct sockaddr *)\u3002\u5e38\u7528 my_addr.sin_addr.s_addr = INADDR_ANY;（\u672c\u673a\u4efb\u610f IP）\u3002<\/p>\n

    listen \/ accept \/ connect<\/h4>\n

    int<\/span> listen<\/span>(<\/span>int<\/span> sockfd,<\/span> int<\/span> backlog)<\/span>;<\/span>
    \nint<\/span> accept<\/span>(<\/span>int<\/span> sockfd,<\/span> struct<\/span> sockaddr<\/span> *<\/span>addr,<\/span> int<\/span> *<\/span>addrlen)<\/span>;<\/span> \/\/ \u8fd4\u56de\u65b0\u7684\u8fde\u63a5 socket（\u6700\u4f4e\u53ef\u7528 fd）<\/span>
    \nint<\/span> connect<\/span>(<\/span>int<\/span> sockfd,<\/span> struct<\/span> sockaddr<\/span> *<\/span>serv_addr,<\/span> int<\/span> addrlen)<\/span>;<\/span><\/p>\n

      \n
    • \u26a0 accept \u88ab\u4fe1\u53f7\u4e2d\u65ad（EINTR）\u6216\u975e\u963b\u585e\u65e0\u8fde\u63a5（EAGAIN）\u65f6，\u91cd\u65b0\u8c03\u7528\u5373\u53ef\u3002<\/li>\n
    • \u26a0 connect \u5931\u8d25\u540e\u8be5 socket \u4e0d\u53ef\u518d\u7528，\u5fc5\u987b close \u540e\u91cd\u65b0 socket\u3002<\/li>\n<\/ul>\n

      \u6536\u53d1<\/h4>\n

      int<\/span> send<\/span>(<\/span>int<\/span> sockfd,<\/span> char<\/span> *<\/span>buff,<\/span> int<\/span> nbytes,<\/span> int<\/span> flags)<\/span>;<\/span>
      \nint<\/span> sendto<\/span>(<\/span>int<\/span> sockfd,<\/span> char<\/span> *<\/span>buff,<\/span> int<\/span> nbytes,<\/span> int<\/span> flags,<\/span> struct<\/span> sockaddr<\/span> *<\/span>to,<\/span> int<\/span> addrlen)<\/span>;<\/span>
      \nint<\/span> recv<\/span>(<\/span>int<\/span> sockfd,<\/span> char<\/span> *<\/span>buff,<\/span> int<\/span> nbytes,<\/span> int<\/span> flags)<\/span>;<\/span>
      \nint<\/span> recvfrom<\/span>(<\/span>int<\/span> sockfd,<\/span> char<\/span> *<\/span>buff,<\/span> int<\/span> nbytes,<\/span> int<\/span> flags,<\/span> struct<\/span> sockaddr<\/span> *<\/span>from,<\/span> int<\/span> addrlen)<\/span>;<\/span><\/p>\n

      send\/recv \u7528\u4e8e\u5df2\u8fde\u63a5\u7684 socket；sendto\/recvfrom \u5e26\u5bf9\u65b9\u5730\u5740，UDP \u7528\u3002
      \nflags：MSG_OOB \u5e26\u5916\u6570\u636e／MSG_PEEK \u7aa5\u89c6／MSG_DONTROUTE \u7ed5\u8fc7\u8def\u7531\u3002
      \n\u26a0 \u5bf9\u5df2\u5173\u95ed\u7684\u8fde\u63a5\u5199\u4f1a\u6536\u5230 SIGPIPE（\u9ed8\u8ba4\u7ec8\u6b62\u8fdb\u7a0b），\u53ef\u8bbe MSG_NOSIGNAL\u3002<\/p>\n

      2.2 \u5b57\u8282\u5e8f\u4e0e\u5730\u5740\u8f6c\u6362<\/h3>\n
        \n
      • \u7f51\u7edc\u5b57\u8282\u5e8f = \u5927\u7aef；\u4e3b\u673a\u53ef\u80fd\u5c0f\u7aef，\u5fc5\u987b\u8f6c\u6362\u3002<\/li>\n<\/ul>\n

        uint32_t<\/span> htonl<\/span>(<\/span>uint32_t<\/span> hostlong)<\/span>;<\/span> uint16_t<\/span> htons<\/span>(<\/span>uint16_t<\/span> hostshort)<\/span>;<\/span> \/\/ \u4e3b\u673a \u2192 \u7f51\u7edc<\/span>
        \nuint32_t<\/span> ntohl<\/span>(<\/span>uint32_t<\/span> netlong)<\/span>;<\/span> uint16_t<\/span> ntohs<\/span>(<\/span>uint16_t<\/span> netshort)<\/span>;<\/span> \/\/ \u7f51\u7edc \u2192 \u4e3b\u673a<\/span><\/p>\n\n\u51fd\u6570\u4f5c\u7528<\/tr>\n\n\n\n\n\n\n\n
        inet_addr(const char *cp)<\/td>\n\u70b9\u5206\u5341\u8fdb\u5236 \u2192 \u7f51\u7edc\u5b57\u8282\u5e8f\u4e8c\u8fdb\u5236<\/td>\n<\/tr>\n
        inet_aton(const char *cp, struct in_addr *inp)<\/td>\n\u540c\u4e0a，\u7ed3\u679c\u5b58\u5165 inp<\/td>\n<\/tr>\n
        inet_ntoa(struct in_addr in)<\/td>\n\u7f51\u7edc\u5b57\u8282\u5e8f \u2192 \u70b9\u5206\u5341\u8fdb\u5236\u5b57\u7b26\u4e32<\/td>\n<\/tr>\n
        inet_network(const char *cp)<\/td>\n\u2192 \u4e3b\u673a\u5b57\u8282\u5e8f 32 \u4f4d<\/td>\n<\/tr>\n
        inet_lnaof(struct in_addr)<\/td>\n\u53d6\u4e3b\u673a\u53f7<\/td>\n<\/tr>\n
        inet_netof(struct in_addr)<\/td>\n\u53d6\u7f51\u7edc\u53f7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        10.20.30.40 \u5bf9\u7167<\/p>\n\n\u7f51\u7edc\u5b57\u8282\u5e8f\u4e3b\u673a\u5b57\u8282\u5e8f\u4e3b\u673a\u53f7\u7f51\u7edc\u53f7<\/tr>\n\n\n
        281E140A<\/td>\n0A141E28<\/td>\n141E28<\/td>\n0A<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        \u26a0 addrstr.s_addr++ \u6539\u7684\u662f\u6700\u9ad8\u5b57\u8282（\u7f51\u7edc\u5b57\u8282\u5e8f），10.20.30.40 \u4f1a\u53d8\u6210 11.20.30.40，\u4e0d\u662f \u202641\u3002<\/p>\n

        2.3 TCP（\u6d41\u5f0f）\u670d\u52a1<\/h3>\n

        \u670d\u52a1\u5668：socket \u2192 bind \u2192 listen \u2192 accept \u2192 recv\/send \u2192 close
        \n\u5ba2\u6237\u7aef：socket \u2192 connect \u2192 send\/recv \u2192 close<\/p>\n

        \/* \u670d\u52a1\u5668：\u6536\u5230\u6574\u6570 +1 \u540e\u8fd4\u56de *\/<\/span>
        \nsock =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
        \nmy_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
        \nmy_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>PORT)<\/span>;<\/span>
        \nmy_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
        \nbind<\/span>(<\/span>sock,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>my_addr,<\/span> sizeof<\/span>(<\/span>my_addr)<\/span>)<\/span>;<\/span>
        \nlisten<\/span>(<\/span>sock,<\/span> 5<\/span>)<\/span>;<\/span><\/p>\n

        while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
        \n new_sock =<\/span> accept<\/span>(<\/span>sock,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>len)<\/span>;<\/span>
        \n printf<\/span>(<\/span>"get connection from %s, port %d socket %d\\\\n"<\/span>,<\/span>
        \n inet_ntoa<\/span>(<\/span>client_addr.<\/span>sin_addr)<\/span>,<\/span> ntohs<\/span>(<\/span>client_addr.<\/span>sin_port)<\/span>,<\/span> new_sock)<\/span>;<\/span>
        \n len =<\/span> recv<\/span>(<\/span>new_sock,<\/span> buf,<\/span> 100<\/span>,<\/span> 0<\/span>)<\/span>;<\/span>
        \n if<\/span> (<\/span>len ==<\/span> 0<\/span>)<\/span> {<\/span> printf<\/span>(<\/span>"the client quit!\\\\n"<\/span>)<\/span>;<\/span> break<\/span>;<\/span> }<\/span> \/\/ \u5bf9\u7aef\u5173\u95ed<\/span>
        \n buf[<\/span>len]<\/span> =<\/span> '\\\\0'<\/span>;<\/span>
        \n recdata =<\/span> atoi<\/span>(<\/span>buf)<\/span> +<\/span> 1<\/span>;<\/span>
        \n sprintf<\/span>(<\/span>buf2,<\/span> "%d"<\/span>,<\/span> recdata)<\/span>;<\/span>
        \n send<\/span>(<\/span>new_sock,<\/span> buf2,<\/span> strlen<\/span>(<\/span>buf2)<\/span>,<\/span> 0<\/span>)<\/span>;<\/span>
        \n close<\/span>(<\/span>new_sock)<\/span>;<\/span>
        \n}<\/span><\/p>\n

        \/* \u5ba2\u6237\u7aef *\/<\/span>
        \nsock =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
        \nmy_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
        \nmy_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>8888<\/span>)<\/span>;<\/span>
        \ninet_aton<\/span>(<\/span>argv[<\/span>1<\/span>]<\/span>,<\/span> (<\/span>struct<\/span> in_addr<\/span> *<\/span>)<\/span>&<\/span>my_addr.<\/span>sin_addr.<\/span>s_addr)<\/span>;<\/span>
        \nconnect<\/span>(<\/span>sock,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>my_addr,<\/span> sizeof<\/span>(<\/span>struct<\/span> sockaddr<\/span>)<\/span>)<\/span>;<\/span>
        \nsend<\/span>(<\/span>sock,<\/span> buf,<\/span> strlen<\/span>(<\/span>buf)<\/span> –<\/span> 1<\/span>,<\/span> 0<\/span>)<\/span>;<\/span>
        \nrecv<\/span>(<\/span>sock,<\/span> recbuf,<\/span> 100<\/span>,<\/span> 0<\/span>)<\/span>;<\/span><\/p>\n

        2.4 UDP（\u6570\u636e\u62a5）\u670d\u52a1<\/h3>\n

        \u670d\u52a1\u5668：socket \u2192 bind \u2192 recvfrom\/sendto \u2192 close （\u65e0 listen\u3001\u65e0 accept）
        \n\u5ba2\u6237\u7aef：socket \u2192 sendto\/recvfrom \u2192 close （\u65e0 connect）<\/p>\n

        sock =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_DGRAM,<\/span> 0<\/span>)<\/span>;<\/span>
        \ns_addr.<\/span>sin_family =<\/span> AF_INET;<\/span>
        \ns_addr.<\/span>sin_port =<\/span> htons<\/span>(<\/span>8888<\/span>)<\/span>;<\/span>
        \ns_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> INADDR_ANY;<\/span>
        \nbind<\/span>(<\/span>sock,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>s_addr,<\/span> sizeof<\/span>(<\/span>s_addr)<\/span>)<\/span>;<\/span><\/p>\n

        len =<\/span> recvfrom<\/span>(<\/span>sock,<\/span> buf,<\/span> sizeof<\/span>(<\/span>buf)<\/span> –<\/span> 1<\/span>,<\/span> 0<\/span>,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>c_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span>
        \nbuf[<\/span>len]<\/span> =<\/span> '\\\\0'<\/span>;<\/span>
        \nsendto<\/span>(<\/span>sock,<\/span> buf2,<\/span> strlen<\/span>(<\/span>buf2)<\/span>,<\/span> 0<\/span>,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>c_addr,<\/span> addr_len)<\/span>;<\/span><\/p>\n

        \/* \u5ba2\u6237\u7aef：.\/udpclient 127.0.0.1 1234 *\/<\/span>
        \nsock =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_DGRAM,<\/span> 0<\/span>)<\/span>;<\/span>
        \ns_addr.<\/span>sin_addr.<\/span>s_addr =<\/span> inet_addr<\/span>(<\/span>argv[<\/span>1<\/span>]<\/span>)<\/span>;<\/span>
        \nstrcpy<\/span>(<\/span>buff,<\/span> argv[<\/span>2<\/span>]<\/span>)<\/span>;<\/span>
        \nsendto<\/span>(<\/span>sock,<\/span> buff,<\/span> strlen<\/span>(<\/span>buff)<\/span>,<\/span> 0<\/span>,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>s_addr,<\/span> addr_len)<\/span>;<\/span>
        \nrecvfrom<\/span>(<\/span>sock,<\/span> buff,<\/span> sizeof<\/span>(<\/span>buff)<\/span> –<\/span> 1<\/span>,<\/span> 0<\/span>,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>s_addr,<\/span> &<\/span>addr_len)<\/span>;<\/span><\/p>\n

        2.5 \u539f\u59cb\u5957\u63a5\u5b57<\/h3>\n

        \u53ef\u81ea\u5df1\u6784\u9020\u534f\u8bae\u5934\u90e8\u3001\u76d1\u542c\u7f51\u7edc\u62a5\u6587（\u666e\u901a socket \u53ea\u80fd\u628a\u6570\u636e\u88c5\u8fdb TCP\/UDP \u5934\u91cc）\u3002ping\u3001traceroute\u3001tcpdump \u90fd\u57fa\u4e8e\u5b83\u3002\u26a0 \u9700 root \u6743\u9650\u3002<\/p>\n

        int<\/span> sockfd =<\/span> socket<\/span>(<\/span>domain,<\/span> SOCK_RAW,<\/span> protocol)<\/span>;<\/span> \/\/ \u7b2c 3 \u4e2a\u53c2\u6570\u901a\u5e38\u4e0d\u4e3a 0<\/span><\/p>\n

        \u94fe\u8def\u5c42：socket(PF_PACKET, type, htons(protocol))<\/p>\n\nprotocol\u4f5c\u7528<\/tr>\n\n\n\n\n\n
        ETH_P_ALL (0x0003)<\/td>\n\u6536\u5230\u6240\u6709\u4e8c\u5c42\u62a5\u6587<\/td>\n<\/tr>\n
        ETH_P_IP (0x0800)<\/td>\n\u53ea\u6536\u76ee\u7684\u4e3a\u672c\u673a IP \u7684\u62a5\u6587（\u5df2\u5265\u94fe\u8def\u5c42\u5934）<\/td>\n<\/tr>\n
        ETH_P_ARP \/ ETH_P_RARP<\/td>\nARP \/ RARP \u62a5\u6587<\/td>\n<\/tr>\n
        \u4e0d\u6307\u5b9a<\/td>\n\u53ea\u80fd\u53d1\u4e0d\u80fd\u6536<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
          \n
        • SOCK_RAW：\u8fde\u94fe\u8def\u5c42\u5934\u90fd\u8981\u81ea\u5df1\u6784\u9020；SOCK_DGRAM：\u5185\u6838\u5e2e\u4f60\u5265\/\u586b\u94fe\u8def\u5c42\u5934\u3002<\/li>\n<\/ul>\n

          \u7f51\u7edc\u5c42：socket(PF_INET, SOCK_RAW, protocol)<\/p>\n\nprotocol\u4f5c\u7528<\/tr>\n\n\n\n
          IPPROTO_TCP \/ UDP \/ ICMP \/ IGMP<\/td>\n\u6536\u5bf9\u5e94\u7c7b\u578b\u62a5\u6587<\/td>\n<\/tr>\n
          IPPROTO_RAW (255)<\/td>\n\u53ea\u80fd\u53d1，\u9700\u81ea\u5df1\u6784\u9020 IP \u9996\u90e8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
            \n
          • \u6536\u5230\u7684\u62a5\u6587\u4ece IP \u9996\u90e8\u5f00\u59cb（\u5df2\u5265\u94fe\u8def\u5c42）；\u53d1\u9001\u65f6\u81ea\u884c\u6784\u9020 TCP\/UDP \u5934，\u8bbe IP_HDRINCL \u540e\u53ef\u81ea\u884c\u6784\u9020 IP \u5934\u3002<\/li>\n
          • \u26a0 TCP\/UDP \u62a5\u6587\u4e0d\u4f1a\u4ea4\u7ed9\u7f51\u7edc\u5c42\u539f\u59cb\u5957\u63a5\u5b57\u3002<\/li>\n<\/ul>\n

            sock =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_RAW,<\/span> IPPROTO_TCP)<\/span>;<\/span> \/\/ \u76d1\u542c TCP \u62a5\u6587<\/span>
            \nSet_Promisc<\/span>(<\/span>"eth0"<\/span>,<\/span> sock)<\/span>;<\/span> \/\/ ioctl + IFF_PROMISC \u8bbe\u6df7\u6742\u6a21\u5f0f<\/span>
            \nn =<\/span> recvfrom<\/span>(<\/span>sock,<\/span> buffer,<\/span> sizeof<\/span>(<\/span>buffer)<\/span>,<\/span> 0<\/span>,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>from,<\/span> &<\/span>fromlen)<\/span>;<\/span>
            \nip =<\/span> (<\/span>struct<\/span> ip<\/span> *<\/span>)<\/span>buffer;<\/span> \/\/ IP \u5934<\/span>
            \ntcp =<\/span> (<\/span>struct<\/span> tcp<\/span> *<\/span>)<\/span>(<\/span>buffer +<\/span> 20<\/span>)<\/span>;<\/span> \/\/ IP \u5934 20 \u5b57\u8282\u540e\u662f TCP \u5934<\/span>
            \nprintf<\/span>(<\/span>"%s \u2192 %s ttl=%d proto=%d port %d\u2192%d\\\\n"<\/span>,<\/span> .<\/span>.<\/span>.<\/span>)<\/span>;<\/span><\/p>\n

            \u4e09. \u9ad8\u7ea7 I\/O<\/h2>\n

            3.1 \u963b\u585e\u4e0e\u975e\u963b\u585e<\/h3>\n
              \n
            • \u963b\u585e（\u9ed8\u8ba4）：read\/write\/send\/recv\/connect\/accept \u90fd\u4f1a\u7b49\u5230\u6709\u7ed3\u679c\u624d\u8fd4\u56de\u3002<\/li>\n
            • \u975e\u963b\u585e：\u8c03\u7528\u7acb\u5373\u8fd4\u56de，\u6ca1\u6570\u636e\/\u6ca1\u8fde\u63a5\u65f6\u8fd4\u56de\u9519\u8bef（\u901a\u5e38\u662f EWOULDBLOCK）\u3002<\/li>\n<\/ul>\n

              \/* fcntl \u65b9\u5f0f *\/<\/span>
              \nflag =<\/span> fcntl<\/span>(<\/span>fd,<\/span> F_GETFL,<\/span> 0<\/span>)<\/span>;<\/span>
              \nflag |=<\/span> O_NONBLOCK;<\/span>
              \nfcntl<\/span>(<\/span>fd,<\/span> F_SETFL,<\/span> flag)<\/span>;<\/span><\/p>\n

              \/* ioctl \u65b9\u5f0f *\/<\/span>
              \nint<\/span> b_on =<\/span> 1<\/span>;<\/span>
              \nioctl<\/span>(<\/span>fd,<\/span> FIONBIO,<\/span> &<\/span>b_on)<\/span>;<\/span> \/\/ 1 \u8bbe\u7f6e\u975e\u963b\u585e，0 \u6e05\u9664<\/span><\/p>\n

              \u975e\u963b\u585e\u4e0b\u5404\u8c03\u7528\u7684\u8fd4\u56de\u503c\u5904\u7406<\/p>\n\n\u8c03\u7528\u5904\u7406<\/tr>\n\n\n\n\n\n
              connect<\/td>\n\u8fd4\u56de -1 \u4e14 errno == EINPROGRESS \u8868\u793a\u63e1\u624b\u8fdb\u884c\u4e2d，\u7528 select \u68c0\u6d4b\u5b8c\u6210<\/td>\n<\/tr>\n
              \u53d1\u9001<\/td>\n\u7f13\u51b2\u533a\u65e0\u7a7a\u95f4\u8fd4\u56de EWOULDBLOCK；\u7a7a\u95f4\u4e0d\u8db3\u5219\u53d1\u591a\u5c11\u7b97\u591a\u5c11，\u5faa\u73af\u7eed\u53d1<\/td>\n<\/tr>\n
              \u63a5\u6536<\/td>\nretval > 0：\u7b49\u4e8e\u8bf7\u6c42\u957f\u5ea6\u8bf4\u660e\u6ca1\u8bfb\u5b8c；< 0：EWOULDBLOCK \u91cd\u8bd5\u3001EINTR \u91cd\u8bd5；== 0 \u5bf9\u7aef\u5df2\u5173\u95ed<\/td>\n<\/tr>\n
              accept<\/td>\n\u65e0\u8fde\u63a5\u65f6\u8fd4\u56de EWOULDBLOCK，\u7ee7\u7eed accept<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              \/* \u975e\u963b\u585e\u53d1\u9001\u9aa8\u67b6 *\/<\/span>
              \nint<\/span> nLeft =<\/span> nLen,<\/span> write_pos =<\/span> 0<\/span>;<\/span>
              \nwhile<\/span> (<\/span>nLeft ><\/span> 0<\/span>)<\/span> {<\/span>
              \n int<\/span> nwrite =<\/span> write<\/span>(<\/span>sock_fd,<\/span> buf +<\/span> write_pos,<\/span> nLeft)<\/span>;<\/span>
              \n if<\/span> (<\/span>nwrite <<\/span> 0<\/span>)<\/span> {<\/span>
              \n if<\/span> (<\/span>errno ==<\/span> EWOULDBLOCK)<\/span> nwrite =<\/span> 0<\/span>;<\/span> \/\/ \u91cd\u53d1<\/span>
              \n else<\/span> return<\/span> –<\/span>1<\/span>;<\/span>
              \n }<\/span>
              \n nLeft -=<\/span> nwrite;<\/span> write_pos +=<\/span> nwrite;<\/span>
              \n}<\/span><\/p>\n

              3.2 select \u591a\u8def\u590d\u7528<\/h3>\n

              \u4e00\u4e2a\u8fdb\u7a0b\u5185\u540c\u65f6\u76d1\u89c6\u591a\u4e2a\u63cf\u8ff0\u7b26，\u8c01\u5c31\u7eea\u5c31\u5904\u7406\u8c01（\u9002\u5408\u591a\u63cf\u8ff0\u7b26，\u5355\u4e2a\u63cf\u8ff0\u7b26\u4e0d\u5982\u76f4\u63a5\u963b\u585e）\u3002<\/p>\n

              int<\/span> select<\/span>(<\/span>int<\/span> numfds,<\/span> fd_set *<\/span>readfds,<\/span> fd_set *<\/span>writefds,<\/span> fd_set *<\/span>exceptfds,<\/span> struct<\/span> timeval<\/span> *<\/span>timeout)<\/span>;<\/span><\/p>\n\n\u53c2\u6570\u8bf4\u660e<\/tr>\n\n\n\n\n
              numfds<\/td>\n\u76d1\u89c6\u7684\u6700\u5927\u63cf\u8ff0\u7b26 + 1<\/td>\n<\/tr>\n
              timeout<\/td>\nNULL \u4e00\u76f4\u7b49；\u5177\u4f53\u503c\u8d85\u65f6\u8fd4\u56de；0 \u7acb\u5373\u8fd4\u56de<\/td>\n<\/tr>\n
              \u8fd4\u56de\u503c<\/td>\n\u5c31\u7eea\u7684\u63cf\u8ff0\u7b26\u6570；0 \u8d85\u65f6；-1 \u51fa\u9519<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              FD_ZERO<\/span>(<\/span>&<\/span>set)<\/span>;<\/span> FD_SET<\/span>(<\/span>fd,<\/span> &<\/span>set)<\/span>;<\/span> FD_CLR<\/span>(<\/span>fd,<\/span> &<\/span>set)<\/span>;<\/span> FD_ISSET<\/span>(<\/span>fd,<\/span> &<\/span>set)<\/span>;<\/span><\/p>\n

              \u5355\u8fdb\u7a0b\u5e76\u53d1\u670d\u52a1\u5668\u9aa8\u67b6<\/p>\n

              while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
              \n FD_ZERO<\/span>(<\/span>&<\/span>fdsr)<\/span>;<\/span>
              \n FD_SET<\/span>(<\/span>sock_fd,<\/span> &<\/span>fdsr)<\/span>;<\/span>
              \n for<\/span> (<\/span>i =<\/span> 0<\/span>;<\/span> i <<\/span> BACKLOG;<\/span> i++<\/span>)<\/span> if<\/span> (<\/span>fd_A[<\/span>i]<\/span>)<\/span> FD_SET<\/span>(<\/span>fd_A[<\/span>i]<\/span>,<\/span> &<\/span>fdsr)<\/span>;<\/span><\/p>\n

              ret =<\/span> select<\/span>(<\/span>maxsock +<\/span> 1<\/span>,<\/span> &<\/span>fdsr,<\/span> NULL<\/span>,<\/span> NULL<\/span>,<\/span> &<\/span>tv)<\/span>;<\/span>
              \n if<\/span> (<\/span>ret ==<\/span> 0<\/span>)<\/span> {<\/span> printf<\/span>(<\/span>"timeout\\\\n"<\/span>)<\/span>;<\/span> continue<\/span>;<\/span> }<\/span><\/p>\n

              for<\/span> (<\/span>i =<\/span> 0<\/span>;<\/span> i <<\/span> conn_amount;<\/span> i++<\/span>)<\/span> \/\/ \u5df2\u6709\u8fde\u63a5\u6709\u6570\u636e<\/span>
              \n if<\/span> (<\/span>FD_ISSET<\/span>(<\/span>fd_A[<\/span>i]<\/span>,<\/span> &<\/span>fdsr)<\/span>)<\/span> {<\/span>
              \n ret =<\/span> recv<\/span>(<\/span>fd_A[<\/span>i]<\/span>,<\/span> buf,<\/span> sizeof<\/span>(<\/span>buf)<\/span>,<\/span> 0<\/span>)<\/span>;<\/span>
              \n if<\/span> (<\/span>ret <=<\/span> 0<\/span>)<\/span> {<\/span> close<\/span>(<\/span>fd_A[<\/span>i]<\/span>)<\/span>;<\/span> FD_CLR<\/span>(<\/span>fd_A[<\/span>i]<\/span>,<\/span> &<\/span>fdsr)<\/span>;<\/span> fd_A[<\/span>i]<\/span> =<\/span> 0<\/span>;<\/span> }<\/span>
              \n else<\/span> printf<\/span>(<\/span>"client[%d] send:%s\\\\n"<\/span>,<\/span> i,<\/span> buf)<\/span>;<\/span>
              \n }<\/span><\/p>\n

              if<\/span> (<\/span>FD_ISSET<\/span>(<\/span>sock_fd,<\/span> &<\/span>fdsr)<\/span>)<\/span> {<\/span> \/\/ \u65b0\u8fde\u63a5<\/span>
              \n new_fd =<\/span> accept<\/span>(<\/span>sock_fd,<\/span> (<\/span>struct<\/span> sockaddr<\/span> *<\/span>)<\/span>&<\/span>client_addr,<\/span> &<\/span>sin_size)<\/span>;<\/span>
              \n fd_A[<\/span>conn_amount++<\/span>]<\/span> =<\/span> new_fd;<\/span>
              \n if<\/span> (<\/span>new_fd ><\/span> maxsock)<\/span> maxsock =<\/span> new_fd;<\/span>
              \n }<\/span>
              \n}<\/span><\/p>\n

              \u26a0 \u5ba2\u6237\u7aef\u9891\u7e41\u65ad\u5f00\/\u8fde\u63a5\u4f1a\u8ba9 maxfd \u8d8a\u6765\u8d8a\u5927，\u5e94\u5728\u6bcf\u6b21 accept \u540e\u91cd\u65b0\u626b\u63cf\u5df2\u6709 fd \u6c42\u6700\u5927\u503c\u3002<\/p>\n

              3.3 poll<\/h3>\n

              int<\/span> poll<\/span>(<\/span>struct<\/span> pollfd<\/span> *<\/span>fds,<\/span> int<\/span> numfds,<\/span> int<\/span> timeout)<\/span>;<\/span> \/\/ timeout \u5355\u4f4d\u6beb\u79d2，\u22640 \u65e0\u9650\u7b49\u5f85<\/span><\/p>\n

              struct<\/span> pollfd<\/span> {<\/span> int<\/span> fd;<\/span> short<\/span> events;<\/span> short<\/span> revents;<\/span> }<\/span>;<\/span><\/p>\n\nevents\u542b\u4e49<\/tr>\n\n\n\n\n\n
              POLLIN<\/td>\n\u6709\u6570\u636e\u53ef\u8bfb<\/td>\n<\/tr>\n
              POLLPRI<\/td>\n\u6709\u7d27\u6025\u6570\u636e\u53ef\u8bfb<\/td>\n<\/tr>\n
              POLLOUT<\/td>\n\u53ef\u5199<\/td>\n<\/tr>\n
              POLLERR \/ POLLHUP \/ POLLNVAL<\/td>\n\u51fa\u9519 \/ \u65ad\u5f00 \/ \u63cf\u8ff0\u7b26\u975e\u6cd5（\u4ec5\u8f93\u51fa）<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              clients[<\/span>0<\/span>]<\/span>.<\/span>fd =<\/span> listenfd;<\/span> clients[<\/span>0<\/span>]<\/span>.<\/span>events =<\/span> POLLIN;<\/span>
              \nfor<\/span> (<\/span>i =<\/span> 1<\/span>;<\/span> i <<\/span> OPEN_MAX;<\/span> i++<\/span>)<\/span> clients[<\/span>i]<\/span>.<\/span>fd =<\/span> –<\/span>1<\/span>;<\/span><\/p>\n

              nready =<\/span> poll<\/span>(<\/span>clients,<\/span> maxi +<\/span> 1<\/span>,<\/span> –<\/span>1<\/span>)<\/span>;<\/span>
              \nif<\/span> (<\/span>clients[<\/span>0<\/span>]<\/span>.<\/span>revents &<\/span> POLLIN)<\/span> {<\/span> connfd =<\/span> accept<\/span>(<\/span>.<\/span>.<\/span>.<\/span>)<\/span>;<\/span> \/* \u627e\u4e00\u4e2a fd == -1 \u7684\u69fd\u4f4d\u653e\u5165 *\/<\/span> }<\/span>
              \nfor<\/span> (<\/span>i =<\/span> 1<\/span>;<\/span> i <<\/span> maxclient;<\/span> i++<\/span>)<\/span>
              \n if<\/span> (<\/span>clients[<\/span>i]<\/span>.<\/span>revents &<\/span> (<\/span>POLLIN |<\/span> POLLERR)<\/span>)<\/span> {<\/span>
              \n nread =<\/span> read<\/span>(<\/span>clients[<\/span>i]<\/span>.<\/span>fd,<\/span> buf,<\/span> MAXLINE)<\/span>;<\/span>
              \n if<\/span> (<\/span>nread <=<\/span> 0<\/span>)<\/span> {<\/span> close<\/span>(<\/span>.<\/span>.<\/span>.<\/span>)<\/span>;<\/span> clients[<\/span>i]<\/span>.<\/span>fd =<\/span> –<\/span>1<\/span>;<\/span> }<\/span>
              \n }<\/span><\/p>\n

              3.4 epoll<\/h3>\n

              \u4e8b\u4ef6\u901a\u77e5\u673a\u5236：\u7cfb\u7edf\u76f4\u63a5\u544a\u8bc9\u7528\u6237\u54ea\u4e9b socket \u6d3b\u8dc3，\u4e0d\u7528\u8f6e\u8be2\u5168\u90e8\u3002<\/p>\n\n\u5bf9\u6bd4select\/pollepoll<\/tr>\n\n\n\n\n
              \u8fde\u63a5\u4e0a\u9650<\/td>\nselect \u4e00\u822c 2048<\/td>\n\u65e0\u786c\u9650\u5236（\u53d7\u6700\u5927\u6253\u5f00\u6587\u4ef6\u6570\u9650\u5236）<\/td>\n<\/tr>\n
              \u6548\u7387<\/td>\n\u904d\u5386\u6574\u4e2a\u96c6\u5408，\u8d8a\u5927\u8d8a\u6162<\/td>\n\u53ea\u5173\u5fc3\u6d3b\u8dc3\u8fde\u63a5，\u4e0e\u603b\u6570\u65e0\u5173<\/td>\n<\/tr>\n
              \u6570\u636e\u4f20\u9012<\/td>\n\u5185\u6838 \u2192 \u7528\u6237\u62f7\u8d1d<\/td>\n\u5171\u4eab\u5185\u5b58<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              int<\/span> epoll_create<\/span>(<\/span>int<\/span> size)<\/span>;<\/span>
              \nint<\/span> epoll_ctl<\/span>(<\/span>int<\/span> epfd,<\/span> int<\/span> op,<\/span> int<\/span> fd,<\/span> struct<\/span> epoll_event<\/span> *<\/span>event)<\/span>;<\/span> \/\/ ADD \/ MOD \/ DEL<\/span>
              \nint<\/span> epoll_wait<\/span>(<\/span>int<\/span> epfd,<\/span> struct<\/span> epoll_event<\/span> *<\/span>events,<\/span> int<\/span> maxevents,<\/span> int<\/span> timeout)<\/span>;<\/span><\/p>\n

              struct<\/span> epoll_event<\/span> {<\/span> uint32_t<\/span> events;<\/span> epoll_data_t<\/span> data;<\/span> }<\/span>;<\/span>
              \ntypedef<\/span> union<\/span> epoll_data {<\/span> void<\/span> *<\/span>ptr;<\/span> int<\/span> fd;<\/span> uint32_t<\/span> u32;<\/span> uint64_t<\/span> u64;<\/span> }<\/span> epoll_data_t<\/span>;<\/span><\/p>\n\nevents\u542b\u4e49<\/tr>\n\n\n\n\n
              EPOLLIN \/ EPOLLOUT<\/td>\n\u53ef\u8bfb \/ \u53ef\u5199<\/td>\n<\/tr>\n
              EPOLLERR \/ EPOLLHUP<\/td>\n\u51fa\u9519 \/ \u6302\u65ad<\/td>\n<\/tr>\n
              EPOLLET<\/td>\n\u8fb9\u7f18\u89e6\u53d1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

              listenfd =<\/span> socket<\/span>(<\/span>AF_INET,<\/span> SOCK_STREAM,<\/span> 0<\/span>)<\/span>;<\/span>
              \nsetnonblocking<\/span>(<\/span>listenfd)<\/span>;<\/span> \/\/ fcntl \u52a0 O_NONBLOCK<\/span>
              \nbind<\/span>(<\/span>.<\/span>.<\/span>.<\/span>)<\/span>;<\/span> listen<\/span>(<\/span>.<\/span>.<\/span>.<\/span>)<\/span>;<\/span>
              \nepollfd =<\/span> epoll_create<\/span>(<\/span>EPOLLSIZE)<\/span>;<\/span>
              \nev.<\/span>events =<\/span> EPOLLIN |<\/span> EPOLLET;<\/span> ev.<\/span>data.<\/span>fd =<\/span> listenfd;<\/span>
              \nepoll_ctl<\/span>(<\/span>epollfd,<\/span> EPOLL_CTL_ADD,<\/span> listenfd,<\/span> &<\/span>ev)<\/span>;<\/span><\/p>\n

              for<\/span> (<\/span>;<\/span>;<\/span>)<\/span> {<\/span>
              \n nfds =<\/span> epoll_wait<\/span>(<\/span>epollfd,<\/span> events,<\/span> curfds,<\/span> –<\/span>1<\/span>)<\/span>;<\/span>
              \n for<\/span> (<\/span>n =<\/span> 0<\/span>;<\/span> n <<\/span> nfds;<\/span> n++<\/span>)<\/span> {<\/span>
              \n if<\/span> (<\/span>events[<\/span>n]<\/span>.<\/span>data.<\/span>fd ==<\/span> listenfd)<\/span> {<\/span> \/\/ \u65b0\u8fde\u63a5<\/span>
              \n connfd =<\/span> accept<\/span>(<\/span>listenfd,<\/span> .<\/span>.<\/span>.<\/span>)<\/span>;<\/span>
              \n setnonblocking<\/span>(<\/span>connfd)<\/span>;<\/span>
              \n ev.<\/span>events =<\/span> EPOLLIN |<\/span> EPOLLET;<\/span> ev.<\/span>data.<\/span>fd =<\/span> connfd;<\/span>
              \n epoll_ctl<\/span>(<\/span>epollfd,<\/span> EPOLL_CTL_ADD,<\/span> connfd,<\/span> &<\/span>ev)<\/span>;<\/span>
              \n }<\/span> else<\/span> {<\/span> \/\/ \u5ba2\u6237\u7aef\u6570\u636e<\/span>
              \n if<\/span> (<\/span>handle<\/span>(<\/span>events[<\/span>n]<\/span>.<\/span>data.<\/span>fd)<\/span> <<\/span> 0<\/span>)<\/span> {<\/span>
              \n epoll_ctl<\/span>(<\/span>epollfd,<\/span> EPOLL_CTL_DEL,<\/span> events[<\/span>n]<\/span>.<\/span>data.<\/span>fd,<\/span> &<\/span>ev)<\/span>;<\/span>
              \n close<\/span>(<\/span>events[<\/span>n]<\/span>.<\/span>data.<\/span>fd)<\/span>;<\/span>
              \n }<\/span>
              \n }<\/span>
              \n }<\/span>
              \n}<\/span><\/p>\n

              \u5b9e\u8df5\u5efa\u8bae：\u76d1\u89c6\u7ebf\u7a0b\u53ea\u505a\u76d1\u89c6，\u4e8b\u4ef6\u4ea4\u7ed9\u7ebf\u7a0b\u6c60\u5904\u7406，\u907f\u514d\u6bcf\u6b21\u4e8b\u4ef6\u6765\u624d\u5efa\u7ebf\u7a0b\u3002<\/p>\n

              \u56db. \u5e76\u53d1\u670d\u52a1\u5668<\/h2>\n

              4.1 \u591a\u8fdb\u7a0b\u6a21\u578b<\/h3>\n

              \u7236\u8fdb\u7a0b：socket \u2192 bind \u2192 listen \u2192 accept \u2192 fork \u2192 \u7ee7\u7eed accept
              \n\u5b50\u8fdb\u7a0b：close(listenfd) \u2192 \u5904\u7406\u8be5\u5ba2\u6237\u7aef \u2192 close(connfd)<\/p>\n

                \n
              • \u5b50\u8fdb\u7a0b\u5904\u7406\u4e00\u4e2a\u5ba2\u6237\u7684\u540c\u65f6，\u7236\u8fdb\u7a0b\u53ef\u7ee7\u7eed\u63a5\u6536\u4e0b\u4e00\u4e2a\u8bf7\u6c42 \u2192 \u63d0\u9ad8\u5e76\u53d1\u3002<\/li>\n
              • \u26a0 \u5b50\u8fdb\u7a0b\u518d fork \u4e00\u4e2a\u5b59\u5b50\u8fdb\u7a0b\u5e72\u6d3b，\u5b50\u8fdb\u7a0b\u76f4\u63a5\u9000\u51fa：\u7236\u8fdb\u7a0b\u4e0d\u5fc5\u7b49\u5b59\u5b50，\u5929\u7136\u907f\u514d\u50f5\u5c38\u8fdb\u7a0b\u3002<\/li>\n<\/ul>\n

                while<\/span> (<\/span>1<\/span>)<\/span> {<\/span>
                \n newconn_fd =<\/span> accept<\/span>(<\/span>sock_fd,<\/span> NULL<\/span>,<\/span> NULL<\/span>)<\/span>;<\/span>
                \n pid =<\/span> fork<\/span>(<\/span>)<\/span>;<\/span>
                \n if<\/span> (<\/span>pid ==<\/span> 0<\/span>)<\/span> {<\/span> \/\/ \u5b50\u8fdb\u7a0b<\/span>
                \n ppid =<\/span> fork<\/span>(<\/span>)<\/span>;<\/span>
                \n if<\/span> (<\/span>ppid ==<\/span> 0<\/span>)<\/span> {<\/span> \/\/ \u5b59\u5b50\u8fdb\u7a0b\u771f\u6b63\u5e72\u6d3b<\/span>
                \n handle_conn<\/span>(<\/span>newconn_fd)<\/span>;<\/span>
                \n close<\/span>(<\/span>sock_fd)<\/span>;<\/span>
                \n }<\/span>
                \n }<\/span>
                \n}<\/span><\/p>\n

                4.2 \u4e09\u79cd\u5e76\u53d1\u65b9\u5f0f\u5bf9\u6bd4<\/h3>\n\n\u65b9\u5f0f\u4f18\u70b9\u7f3a\u70b9<\/tr>\n\n\n\n\n
                \u591a\u8fdb\u7a0b\/\u591a\u7ebf\u7a0b<\/td>\n\u6a21\u578b\u7b80\u5355\u3001\u5e76\u53d1\u6027\u597d<\/td>\n\u9700\u5904\u7406\u540c\u6b65\u4e92\u65a5；\u963b\u585e\u7b49\u5f85<\/td>\n<\/tr>\n
                select\/poll<\/td>\n\u5355\u8fdb\u7a0b\u670d\u52a1\u591a\u8fde\u63a5，\u65e0\u540c\u6b65\u4e92\u65a5\u95ee\u9898<\/td>\n\u8981\u4e0d\u65ad\u8f6e\u8be2，\u63cf\u8ff0\u7b26\u8d8a\u591a\u8d8a\u6162<\/td>\n<\/tr>\n
                epoll<\/td>\n\u4e8b\u4ef6\u901a\u77e5，\u53ea\u5904\u7406\u6d3b\u8dc3\u8fde\u63a5，\u9002\u5408\u5927\u91cf\u8fde\u63a5<\/td>\nLinux \u7279\u6709<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"

                \u4e00. \u8ba1\u7b97\u673a\u7f51\u7edc\u6982\u8ff0
                \n1.1 TCP\/IP \u4e94\u5c42\u6a21\u578b\u5c42\u540d\u79f0\u8981\u70b95\u5e94\u7528\u5c42\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u4e92\u8054\u7f51\u7684\u89c4\u7a0b4\u4f20\u8f93\u5c42TCP\/UDP；\u8fdb\u7a0b\u5230\u8fdb\u7a0b\u7684\u901a\u4fe1\u3001\u6d41\u91cf\u63a7\u5236\u3001\u5dee\u9519\u63a7\u52363\u4e92\u8054\u7f51\u5c42IP；\u4e0d\u53ef\u9760\u3001\u65e0\u8fde\u63a5\u3001\u5c3d\u6700\u5927\u52aa\u529b\u4ea4\u4ed8；32 \u4f4d IP \u5730\u57402\u6570\u636e\u94fe\u8def\u5c42\u7ec4\u5e27\u4e0e\u4f20\u5e27（\u5e27\u662f\u4f20\u8f93\u5355\u4f4d）1\u7269\u7406\u5c42\u786c\u4ef6\u8bbe\u5907\u7684\u7535\u6c14\u7279\u6027\u89c4\u8303\u6536\u53d1\u6d41\u7a0b：\u53d1\u9001\u65f6\u81ea\u4e0a\u800c\u4e0b \u63d2\u53e3\u5c42 \u2192 \u534f\u8bae\u5c42（\u52a0 TCP\/UDP \u5934 \u2192 \u52a0 IP \u5934&#x<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[58,78,44],"topic":[],"class_list":["post-115231","post","type-post","status-publish","format-standard","hentry","category-server","tag-linux","tag-78","tag-44"],"yoast_head":"\n30\u5929\u901f\u901aLinux \u7b2c\u4e5d\u7ae0Linux\u7f51\u7edc\u7f16\u7a0b - \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\/115231.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"30\u5929\u901f\u901aLinux \u7b2c\u4e5d\u7ae0Linux\u7f51\u7edc\u7f16\u7a0b - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"\u4e00. \u8ba1\u7b97\u673a\u7f51\u7edc\u6982\u8ff0 1.1 TCP\/IP \u4e94\u5c42\u6a21\u578b\u5c42\u540d\u79f0\u8981\u70b95\u5e94\u7528\u5c42\u5e94\u7528\u7a0b\u5e8f\u4f7f\u7528\u4e92\u8054\u7f51\u7684\u89c4\u7a0b4\u4f20\u8f93\u5c42TCP\/UDP；\u8fdb\u7a0b\u5230\u8fdb\u7a0b\u7684\u901a\u4fe1\u3001\u6d41\u91cf\u63a7\u5236\u3001\u5dee\u9519\u63a7\u52363\u4e92\u8054\u7f51\u5c42IP；\u4e0d\u53ef\u9760\u3001\u65e0\u8fde\u63a5\u3001\u5c3d\u6700\u5927\u52aa\u529b\u4ea4\u4ed8；32 \u4f4d IP \u5730\u57402\u6570\u636e\u94fe\u8def\u5c42\u7ec4\u5e27\u4e0e\u4f20\u5e27（\u5e27\u662f\u4f20\u8f93\u5355\u4f4d）1\u7269\u7406\u5c42\u786c\u4ef6\u8bbe\u5907\u7684\u7535\u6c14\u7279\u6027\u89c4\u8303\u6536\u53d1\u6d41\u7a0b：\u53d1\u9001\u65f6\u81ea\u4e0a\u800c\u4e0b \u63d2\u53e3\u5c42 \u2192 \u534f\u8bae\u5c42（\u52a0 TCP\/UDP \u5934 \u2192 \u52a0 IP \u5934&#x\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/115231.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2026-10-11T06:48:54+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"7 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/115231.html\",\"url\":\"https:\/\/www.wsisp.com\/helps\/115231.html\",\"name\":\"30\u5929\u901f\u901aLinux \u7b2c\u4e5d\u7ae0Linux\u7f51\u7edc\u7f16\u7a0b - 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