linux网络编程三：recv, send 的调用

来源：互联网发布：网络教育高起专编辑：程序博客网时间：2024/06/05 17:18

最近在看《linux高性能服务器编程》，在此做个日记，以激励自己，同时分享于有需要的朋友。

#include <sys/types.h>#include <sys/socket.h>ssize_t recv(int sockfd, void *buf, size_t len, int flags);ssize_t send(int sockfd, const void *buf, size_t len, int flags);

1. recv读取socfd 上的数据， buf和len参数分别指定读缓冲区的位置和大小，flags参数通常设置为0,它为数据收发提供了额处的控制，比如MSG_OOB，用于发送或接收紧急数据，具体可查阅手册。

调用成功时返回实际读取到的数据长度，它可能小于我们期望的长度len。因此我们可能要多次调用 recv 才能读取完整的数据。它也可能返回0, 意味着通信对方关闭了连接。出错时返回-1,并设置errno。

2. send往sockfd写入数据，buf和len参数分别指定写缓冲区的位置和大小。

调用成功时返回实际写入的数据长度，失败时返回-1,并设置errno。

//客户端代码#include <stdio.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <stdlib.h>#include <unistd.h>#include <string.h>int main(int argc, char **argv){if (argc != 3) {fprintf(stderr, "Usage: %s ip port\n", basename(argv[0]));return 1;}const char *ip = argv[1];int port = atoi(argv[2]);struct sockaddr_in server_address;bzero(&server_address, sizeof(server_address));server_address.sin_family = AF_INET;server_address.sin_port = htons(port);inet_pton(AF_INET, ip, &server_address.sin_addr);int sockfd = socket(PF_INET, SOCK_STREAM, 0);assert(sockfd >= 0);if (connect(sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) {fprintf(stderr, "connection failed\n");}else {fprintf(stderr, "send oob data out\n");const char *oob_data = "abc";const char *normal_data = "123";send(sockfd, normal_data, strlen(normal_data), 0);send(sockfd, oob_data, strlen(oob_data), MSG_OOB); //发送外带紧急数据send(sockfd, normal_data, strlen(normal_data), 0);}close(sockfd);return 0;}

//服务端代码#include <stdio.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#define BUF_SIZE 1024int main(int argc, char **argv){if(argc != 3) {fprintf(stderr, "Usage: %s ip port\n", basename(argv[0]));return 1;}const char *ip = argv[1];int port = atoi(argv[2]);struct sockaddr_in address;bzero(&address, sizeof(address));address.sin_family = AF_INET;address.sin_port = htons(port);inet_pton(AF_INET, ip, &address.sin_addr);int sock = socket(PF_INET, SOCK_STREAM, 0);assert(sock >= 0);int reuse = 1;setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizof(reuse));int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));assert(ret != -1);ret = listen(sock, 5);assert(ret != -1);struct sockaddr_in client;socklen_t client_addrlength = sizeof(client);int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);if (connfd < 0) {fprintf(stderr, "errno is:%s\n", strerror(errno));}else {char buffer[BUF_SIZE];memset(buffer, '\0', BUF_SIZE);ret = recv(connfd, buffer, BUF_SIZE-1, 0);fprintf(stderr, "got %d bytes of normal data '%s'\n", ret, buffer);memset(buffer, '\0', BUF_SIZE);ret = recv(connfd, buffer, BUF_SIZE-1, MSG_OOB);  //接收外带紧急数据fprintf(stderr, "got %d bytes of oob data '%s'\n", ret, buffer);memset(buffer, '\0', BUF_SIZE);ret = recv(connfd, buffer, BUF_SIZE-1, 0);fprintf(stderr, "got %d bytes of normal data '%s'\n", ret, buffer);close(connfd);}close(sock);return 0;}

0 0