按行读取解决粘包问题

该方案，每次读取时当读到‘\n’换行符时，读取该行

服务器端：

#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(1)struct packet{int len;char buf[1024];};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 = bufp + nread;nleft = nleft - nread;}return count;}ssize_t writen(int fd, void *buf, size_t count){size_t nleft = count;ssize_t nwrite;char *bufp = (char*)buf;while (nleft > 0){if ((nwrite = write(fd, bufp, nleft)) < 0){if (errno == EINTR){continue;return -1;}else if (nwrite == 0)continue;}bufp = bufp + nwrite;nleft = nleft - nwrite;}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 = (char*)buf;int nleft = maxline;while (1){ret = recv_peek(sockfd, bufp, nleft);if (ret < 0)return ret;else if (ret == 0)return ret;//对方关闭了套接口nread = ret;for (int i = 0; i < nread; i++){if (bufp[i] == '\n'){ret = readn(sockfd, bufp, i + 1);//将缓冲区数据移除if (ret != i + 1)exit(EXIT_FAILURE);return ret;}}if (nread>nleft)exit(EXIT_FAILURE);//读到的数据不能超过缓冲区nleft -= nread;ret = readn(sockfd, bufp, nread);if (ret != nread)exit(EXIT_FAILURE);bufp += nread;}return -1;}void do_service(int connfd){char recvbuf[1024];int n;while (1){memset(&recvbuf, 0, sizeof(recvbuf));int ret = readline(connfd, recvbuf, 1204);if (ret == -1){ERR_EXIT("read");}else if (ret ==0 ){printf("client cloase\n");break;}fputs(recvbuf, stdout);writen(connfd, recvbuf, strlen(recvbuf));}}int main(void){int listenfd;if ((listenfd = socket(AF_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);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("listten");while (1){int connfd;struct sockaddr_in peeraddr;socklen_t peerlen = sizeof(peeraddr);if ((connfd = 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_t pid = fork();if (pid == -1)ERR_EXIT("fork");if (pid == 0){close(listenfd);do_service(connfd);exit(EXIT_SUCCESS);}if (pid > 0){close(connfd);}}close(listenfd);}

客户端：

#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(1)struct packet{int len;char buf[1024];};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 = bufp + nread;nleft = nleft - nread;}return count;}ssize_t writen(int fd, void *buf, size_t count){size_t nleft = count;ssize_t nwrite;char *bufp = (char*)buf;while (nleft > 0){if ((nwrite = write(fd, bufp, nleft)) < 0){if (errno == EINTR){continue;return -1;}else if (nwrite == 0)continue;}bufp = bufp + nwrite;nleft = nleft - nwrite;}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 = (char*)buf;int nleft = maxline;while (1){ret = recv_peek(sockfd, bufp, nleft);if (ret < 0)return ret;else if (ret == 0)return ret;//对方关闭了套接口nread = ret;for (int i = 0; i < nread; i++){if (bufp[i] == '\n'){ret = readn(sockfd, bufp, i + 1);//将缓冲区数据移除if (ret != i + 1)exit(EXIT_FAILURE);return ret;}}if (nread>nleft)exit(EXIT_FAILURE);//读到的数据不能超过缓冲区nleft -= nread;ret = readn(sockfd, bufp, nread);if (ret != nread)exit(EXIT_FAILURE);bufp += nread;}return -1;}int main(void){int sockfd;if ((sockfd = socket(AF_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 = inet_addr("127.0.1");if (connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)ERR_EXIT("bind");char sendbuf[1024];char recvbuf[1024];memset(sendbuf, 0, sizeof(sendbuf));memset(recvbuf, 0, sizeof(recvbuf));while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL){writen(sockfd, sendbuf, strlen(sendbuf));int ret = readline(sockfd, recvbuf, sizeof(recvbuf));if (ret == -1)ERR_EXIT("read");if (ret == 0){printf("server close\n");break;}fputs(recvbuf, stdout);memset(sendbuf, 0, sizeof(sendbuf));memset(recvbuf, 0, sizeof(recvbuf));}close(sockfd);}