socket编程端口复用问题_course

socket编程，想将几个客户端，绑定到同一个端口上，第一个可以绑定成功，第二个bind返回错误，errno=98(address already in use),我在socket选项里已经加上了，地

C++ socket端口复用的问题_course

环境 公网服务器1台，内网服务器若干。其中一台内网可以和公网连接通信，打算在公网上用socket做端口转发来实现访各台问内网的目的。功能已经实现了（一对一连接），但端口复用问题一直很困惑，请各位帮忙检查一下代码，谢谢 公网代码 ``` // 绑定两个服务器socket void bind2bind(int port1, int port2) { char msgbuf[100]; memset(msgbuf, 0, 100); sprintf(msgbuf, "[+] 服务器初始化...\r\n"); outprint(msgbuf, strlen(msgbuf)); int fd0, fd1, fd2; if ((fd0 = create_socket()) == 0) return; if ((fd1 = create_socket()) == 0) return; if ((fd2 = create_socket()) == 0) return; int port0 = 5501; if (create_server(fd0, port0) == 0) { closesocket(fd0); return; } sprintf(msgbuf, "[+] 成功监听通信端口: %d\r\n", port0); outprint(msgbuf, strlen(msgbuf)); // 创建第一个服务器 if (create_server(fd1, port1) == 0) { closesocket(fd1); return; } sprintf(msgbuf, "[+] 成功监听隧道端口: %d\r\n", port1); outprint(msgbuf, strlen(msgbuf)); // 创建第二个服务器 if (create_server(fd2, port2) == 0) { closesocket(fd2); return; } sprintf(msgbuf, "[+] 成功监听上线端口: %d\r\n", port2); outprint(msgbuf, strlen(msgbuf)); // 等待两端上线 while (1) { sprintf(msgbuf, "[%d] 正在建立通信端口: %d\r\n", idx, port0); outprint(msgbuf, strlen(msgbuf)); struct sockaddr_in client0; int size0 = sizeof(struct sockaddr); int sockfd0 = accept(fd0, (struct sockaddr *)&client0, &size0); sprintf(msgbuf, "[%d] 通信端口连接成功 IP地址: %s\r\n", idx, inet_ntoa(client0.sin_addr)); outprint(msgbuf, strlen(msgbuf)); sprintf(msgbuf, "[%d] 发送idx值: %d\r\n", idx, idx); outprint(msgbuf, strlen(msgbuf)); char idxbuf[10]; memset(idxbuf, 0, 10); sprintf(idxbuf, "%d", idx); int send0 = send(sockfd0, idxbuf, strlen(idxbuf)+1, 0); if (send0 <= 0) { closesocket(sockfd0); continue; } closesocket(sockfd0); sprintf(msgbuf, "[%d] 正在建立隧道端口: %d\r\n", idx, port1); outprint(msgbuf, strlen(msgbuf)); struct sockaddr_in client1; int size1 = sizeof(struct sockaddr); int sockfd1 = accept(fd1, (struct sockaddr *)&client1, &size1); sprintf(msgbuf, "[%d] 正在建立上线端口: %d\r\n", idx, port2); outprint(msgbuf, strlen(msgbuf)); struct sockaddr_in client2; int size2 = sizeof(struct sockaddr); int sockfd2 = accept(fd2, (struct sockaddr *)&client2, &size2); sprintf(msgbuf, "[%d] 通过上线端口连接成功 IP地址: %s\r\n", idx, inet_ntoa(client2.sin_addr)); outprint(msgbuf, strlen(msgbuf)); // socket transocket sock; sock.fd1 = sockfd1; sock.fd2 = sockfd2; sock.idx = idx; CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, NULL); idx++; } } ``` ``` 负责通信的内网代码 { int port0 = 5501; char msgbuf[100]; memset(msgbuf, 0, 100); while (1) { int sockfd0; if ((sockfd0 = create_socket()) == 0) return 0; // 通过5501端口连接服务器 sprintf(msgbuf, "[+] 正在连接服务器 %s:%d\r\n", sConnectHost, port0); outprint(msgbuf, strlen(msgbuf)); if (client_connect(sockfd0, sConnectHost, port0) == 0) { closesocket(sockfd0); continue; } sprintf(msgbuf, "[+] 服务器连接成功\r\n"); outprint(msgbuf, strlen(msgbuf)); // 接收服务器idx值 char idxbuf[10]; memset(idxbuf, 0, 10); int read0 = recv(sockfd0, idxbuf, 10, 0); if (read0 > 0) { // 在线程内执行conn2conn int nIdx = atoi(idxbuf); tranconn2conn conn; conn.host1 = sConnectHost; conn.port1 = iConnectPort; conn.host2 = sTransmitHost; conn.port2 = iTransmitPort; conn.idx = nIdx; CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)conn2conn, (LPVOID)&conn, 0, NULL); } } closeallfd(); } // 内网转发数据 void conn2conn(LPVOID data) { tranconn2conn *conn = (tranconn2conn *)data; char msgbuf[100]; memset(msgbuf, 0, 100); while (1) { int sockfd1, sockfd2; if ((sockfd1 = create_socket()) == 0) return; if ((sockfd2 = create_socket()) == 0) return; sprintf(msgbuf, "[%d] 正在连接服务器 %s:%d\r\n", conn->idx, conn->host1, conn->port1); outprint(msgbuf, strlen(msgbuf)); if (client_connect(sockfd1, conn->host1, conn->port1) == 0) { closesocket(sockfd1); closesocket(sockfd2); continue; } sprintf(msgbuf, "[%d] 服务器连接成功\r\n", conn->idx); outprint(msgbuf, strlen(msgbuf)); sprintf(msgbuf, "[%d] 正在连接内网 %s:%d\r\n", conn->idx, conn->host2, conn->port2); outprint(msgbuf, strlen(msgbuf)); if (client_connect(sockfd2, conn->host2, conn->port2) == 0) { closesocket(sockfd1); closesocket(sockfd2); continue; } sprintf(msgbuf, "[%d] 内网连接成功\r\n", conn->idx); outprint(msgbuf, strlen(msgbuf)); // socket transocket sock; sock.fd1 = sockfd1; sock.fd2 = sockfd2; sock.idx = conn->idx; transmitdata(&sock); } } ``` ``` 数据转发代码 // 服务器转发数据 void transmitdata(LPVOID data) { transocket *sock = (transocket *)data; // 准备采用select模型 fd_set readfd, writefd; char read_in1[MAXSIZE], send_out1[MAXSIZE]; char read_in2[MAXSIZE], send_out2[MAXSIZE]; struct sockaddr_in client1, client2; char host1[20], host2[20], msgbuf[100]; memset(host1, 0, 20); memset(host2, 0, 20); memset(msgbuf, 0, 100); int port1 = 0, port2 = 0; int structsize1 = sizeof(struct sockaddr); int structsize2 = sizeof(struct sockaddr); // 获取第一客户端信息 if (getpeername(sock->fd1, (struct sockaddr *)&client1, &structsize1) < 0) { strcpy(host1, "fd1"); } else { strcpy(host1, inet_ntoa(client1.sin_addr)); port1 = ntohs(client1.sin_port); } // 获取第二客户端信息 if (getpeername(sock->fd2, (struct sockaddr *)&client2, &structsize2) < 0) { strcpy(host2, "fd2"); } else { strcpy(host2, inet_ntoa(client2.sin_addr)); port2 = ntohs(client2.sin_port); } sprintf(msgbuf, "[%d] fd1: %d, fd2: %d\r\n", sock->idx, sock->fd1, sock->fd2); outprint(msgbuf, strlen(msgbuf)); // 输出两个客户端信息 sprintf(msgbuf, "[%d] 建立数据转发走向(%s:%d <-> %s:%d)\r\n", sock->idx, host1, port1, host2, port2); outprint(msgbuf, strlen(msgbuf)); // 最大检测数目 int maxfd = max(sock->fd1, sock->fd2) + 1; // 设置检测超时 struct timeval timeset; timeset.tv_sec = TIMEOUT; // 超时秒数 timeset.tv_usec = 0; // 超时微秒 // 位模式清零 memset(send_out1, 0, MAXSIZE); memset(send_out2, 0, MAXSIZE); // 可读长度 int totalread1 = 0, totalread2 = 0; while (1) { // 采用select异步模型 FD_ZERO(&readfd); FD_ZERO(&writefd); // 添加到fd集合 FD_SET(sock->fd1, &readfd); FD_SET(sock->fd1, &writefd); FD_SET(sock->fd2, &readfd); FD_SET(sock->fd2, &writefd); // 第一个参数会被系统忽略掉 int result = select(maxfd, &readfd, &writefd, NULL, &timeset); if ((result < 0) && (errno != EINTR)) { // 程序出错 sprintf(msgbuf, "[%d] Error: select函数出错\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); break; } else if (result == 0) { // 等待超时 sprintf(msgbuf, "[%d] Error: select函数等待超时\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); continue; } // fd1可读, 只要可读, 一次即可读取完整, 无需while循环 if (FD_ISSET(sock->fd1, &readfd) && totalread1 < MAXSIZE) { int read1 = recv(sock->fd1, read_in1, MAXSIZE - totalread1, 0); if (read1 == 0 || (read1 < 0 && errno != EINTR)) { sprintf(msgbuf, "[%d] Error: 读取fd1出错\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); break; } // 改变fd1的发送缓冲区和他的大小（接了就要发嘛） memcpy(send_out1 + totalread1, read_in1, read1); sprintf(msgbuf, "[%d] fd1成功在地址: %16s:%d上面读取%d字节\r\n", sock->idx, host1, port1, read1); outprint(msgbuf, strlen(msgbuf)); totalread1 += read1; memset(read_in1, 0, MAXSIZE); } // fd2可写 if (FD_ISSET(sock->fd2, &writefd)) { int err = 0; int sendcount1 = 0; // 发送的话可能一次发不完（数据包过大） while (totalread1 > 0) { int send1 = send(sock->fd2, send_out1+sendcount1, totalread1, 0); if (send1 == 0 || (send1 < 0 && errno != EINTR)) { sprintf(msgbuf, "[%d] Error: 写入fd2出错\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); err = 1; break; } if ((send1 < 0) && (errno == ENOSPC)) break; // 改变缓冲区大小 sendcount1 += send1; totalread1 -= send1; sprintf(msgbuf, "[%d] fd2成功在地址: %16s:%d上面发送%d字节\r\n", sock->idx, host2, port2, send1); outprint(msgbuf, strlen(msgbuf)); } // 检验出错 if (err == 1) break; // 如果发送了数据, 并且没有发送干净 if ((totalread1 > 0) && (sendcount1 > 0)) { // 理论上下面两行永远不会执行 memcpy(send_out1, send_out1 + sendcount1, totalread1); memset(send_out1 + totalread1, 0, MAXSIZE - totalread1); } else { memset(send_out1, 0, MAXSIZE); } } // fd2可读, 只要可读, 一次即可读取完整, 无需while循环 if (FD_ISSET(sock->fd2, &readfd) && totalread2 < MAXSIZE) { int read2 = recv(sock->fd2, read_in2, MAXSIZE - totalread2, 0); if (read2 == 0 || (read2 < 0 && errno != EINTR)) { sprintf(msgbuf, "[%d] Error: 读取fd2出错\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); break; } // 接了就立即发出去 memcpy(send_out2 + totalread2, read_in2, read2); sprintf(msgbuf, "[%d] fd2成功在地址: %16s:%d上面读取%d字节\r\n", sock->idx, host2, port2, read2); outprint(msgbuf, strlen(msgbuf)); totalread2 += read2; memset(read_in2, 0, MAXSIZE); } // fd1可写 if (FD_ISSET(sock->fd1, &writefd)) { int err2 = 0; int sendcount2 = 0; while (totalread2 > 0) { int send2 = send(sock->fd1, send_out2 + sendcount2, totalread2, 0); if (send2 == 0 || (send2 < 0 && errno != EINTR)) { sprintf(msgbuf, "[%d] Error: 写入fd1出错\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); err2 = 1; break; } if ((send2 < 0) && (errno == ENOSPC)) break; sendcount2 += send2; totalread2 -= send2; sprintf(msgbuf, "[%d] fd1成功在地址: %16s:%d上面发送%d字节\r\n", sock->idx, host1, port1, send2); outprint(msgbuf, strlen(msgbuf)); } if (err2 == 1) break; if ((totalread2 > 0) && (sendcount2 > 0)) { memcpy(send_out2, send_out2+sendcount2, totalread2); memset(send_out2 + totalread2, 0, MAXSIZE - totalread2); } else { memset(send_out2, 0, MAXSIZE); } } } // 关闭socket closesocket(sock->fd1); closesocket(sock->fd2); sprintf(msgbuf, "[%d] 成功关闭掉两个socket, fd1, fd2\r\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); sprintf(msgbuf, "[%d] 本次数据转发结束\r\n\n", sock->idx); outprint(msgbuf, strlen(msgbuf)); } ```

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