#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)ssize_t readn(int fd, void *buf, size_t count)
{size_t nleft = count;ssize_t nread;char *bufp = (char*)buf;while (nleft > 0){if ((nread = read(fd, bufp, nleft)) < 0){if (errno == EINTR)continue;return -1;}else if (nread == 0)return count - nleft;bufp += nread;nleft -= nread;}return count;
}ssize_t writen(int fd, const void *buf, size_t count)
{size_t nleft = count;ssize_t nwritten;char *bufp = (char*)buf;while (nleft > 0){if ((nwritten = write(fd, bufp, nleft)) < 0){if (errno == EINTR)continue;return -1;}else if (nwritten == 0)continue;bufp += nwritten;nleft -= nwritten;}return count;
}ssize_t recv_peek(int sockfd, void *buf, size_t len)
{while (1){int ret = recv(sockfd, buf, len, MSG_PEEK);if (ret == -1 && errno == EINTR)continue;return ret;}
}ssize_t readline(int sockfd, void *buf, size_t maxline)
{int ret;int nread;char *bufp = buf;int nleft = maxline;while (1){ret = recv_peek(sockfd, bufp, nleft);if (ret < 0)return ret;else if (ret == 0)return ret;nread = ret;int i;for (i=0; i<nread; i++){if (bufp[i] == '\n'){ret = readn(sockfd, bufp, i+1);if (ret != i+1)exit(EXIT_FAILURE);return ret;}}if (nread > nleft)exit(EXIT_FAILURE);nleft -= nread;ret = readn(sockfd, bufp, nread);if (ret != nread)exit(EXIT_FAILURE);bufp += nread;}return -1;
}void echo_srv(int conn)//由于这个函数的意义就是回显消息给客户端，所以改一个函数名
{char recvbuf[1024];while (1){memset(recvbuf, 0, sizeof(recvbuf));int ret = readline(conn, recvbuf, 1024);if (ret == -1)ERR_EXIT("readline");if (ret == 0){printf("client close\n");break;}fputs(recvbuf, stdout);writen(conn, recvbuf, strlen(recvbuf));}
}int main(void)
{int listenfd;if ((listenfd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
/*    if ((listenfd = socket(PF_INET, SOCK_STREAM, 0)) < 0)*/ERR_EXIT("socket");struct sockaddr_in servaddr;memset(&servaddr, 0, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(5188);servaddr.sin_addr.s_addr = htonl(INADDR_ANY);/*servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");*//*inet_aton("127.0.0.1", &servaddr.sin_addr);*/int on = 1;if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)ERR_EXIT("setsockopt");if (bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)ERR_EXIT("bind");if (listen(listenfd, SOMAXCONN) < 0)ERR_EXIT("listen");struct sockaddr_in peeraddr;socklen_t peerlen = sizeof(peeraddr);int conn;pid_t pid;while (1){if ((conn = accept(listenfd, (struct sockaddr*)&peeraddr, &peerlen)) < 0)ERR_EXIT("accept");printf("ip=%s port=%d\n", inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port));pid = fork();if (pid == -1)ERR_EXIT("fork");if (pid == 0){close(listenfd);echo_srv(conn);exit(EXIT_SUCCESS);}elseclose(conn);}return 0;
}

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)ssize_t readn(int fd, void *buf, size_t count)
{size_t nleft = count;ssize_t nread;char *bufp = (char*)buf;while (nleft > 0){if ((nread = read(fd, bufp, nleft)) < 0){if (errno == EINTR)continue;return -1;}else if (nread == 0)return count - nleft;bufp += nread;nleft -= nread;}return count;
}ssize_t writen(int fd, const void *buf, size_t count)
{size_t nleft = count;ssize_t nwritten;char *bufp = (char*)buf;while (nleft > 0){if ((nwritten = write(fd, bufp, nleft)) < 0){if (errno == EINTR)continue;return -1;}else if (nwritten == 0)continue;bufp += nwritten;nleft -= nwritten;}return count;
}ssize_t recv_peek(int sockfd, void *buf, size_t len)
{while (1){int ret = recv(sockfd, buf, len, MSG_PEEK);if (ret == -1 && errno == EINTR)continue;return ret;}
}ssize_t readline(int sockfd, void *buf, size_t maxline)
{int ret;int nread;char *bufp = buf;int nleft = maxline;while (1){ret = recv_peek(sockfd, bufp, nleft);if (ret < 0)return ret;else if (ret == 0)return ret;nread = ret;int i;for (i=0; i<nread; i++){if (bufp[i] == '\n'){ret = readn(sockfd, bufp, i+1);if (ret != i+1)exit(EXIT_FAILURE);return ret;}}if (nread > nleft)exit(EXIT_FAILURE);nleft -= nread;ret = readn(sockfd, bufp, nread);if (ret != nread)exit(EXIT_FAILURE);bufp += nread;}return -1;
}void echo_cli(int sock)//将之前这一段代码封装成一个函数，回显客户端，让其代码更加整洁。
{char sendbuf[1024] = {0};char recvbuf[1024] = {0};while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL){writen(sock, sendbuf, strlen(sendbuf));int ret = readline(sock, recvbuf, sizeof(recvbuf));if (ret == -1)ERR_EXIT("readline");else if (ret == 0){printf("client close\n");break;}fputs(recvbuf, stdout);memset(sendbuf, 0, sizeof(sendbuf));memset(recvbuf, 0, sizeof(recvbuf));}close(sock);
}int main(void)
{int sock;if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)ERR_EXIT("socket");struct sockaddr_in servaddr;memset(&servaddr, 0, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(5188);servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");if (connect(sock, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)ERR_EXIT("connect");struct sockaddr_in localaddr;socklen_t addrlen = sizeof(localaddr);if (getsockname(sock, (struct sockaddr*)&localaddr, &addrlen) < 0)ERR_EXIT("getsockname");printf("ip=%s port=%d\n", inet_ntoa(localaddr.sin_addr), ntohs(localaddr.sin_port));echo_cli(sock);return 0;
}