距离详解Linux下的UDP方式通讯

2020-01-26 14:50:21

字体：大中小

来源：转载

供稿：网友

UDP方式点对点通讯

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;struct sockaddr_in c_addr;int sock;socklen_t addr_len;int len;char buff[128];/* 创建 socket , 关键在于这个 SOCK_DGRAM */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");memset(&s_addr, 0, sizeof(struct sockaddr_in));/* 设置地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);elses_addr.sin_addr.s_addr = INADDR_ANY;/* 绑定地址和端口信息 */if ((bind(sock, (struct sockaddr *) &s_addr, sizeof(s_addr))) == -1) {perror("bind");exit(errno);} elseprintf("bind address to socket./n/r");/* 循环接收数据 */addr_len = sizeof(c_addr);while (1) {len = recvfrom(sock, buff, sizeof(buff) - 1, 0,(struct sockaddr *) &c_addr, &addr_len);if (len < 0) {perror("recvfrom");exit(errno);}buff[len] = '/0';printf("收到来自%s:%d的消息:%s/n/r",inet_ntoa(c_addr.sin_addr), ntohs(c_addr.sin_port), buff);}return 0;}

客户端源代码如下：

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;int sock;int addr_len;int len;char buff[128];/* 创建 socket , 关键在于这个 SOCK_DGRAM */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");/* 设置对方地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);else {printf("消息必须有一个接收者！/n");exit(0);}/* 发送UDP消息 */addr_len = sizeof(s_addr);strcpy(buff, "hello i'm here");len = sendto(sock, buff, strlen(buff), 0,(struct sockaddr *) &s_addr, addr_len);if (len < 0) {printf("/n/rsend error./n/r");return 3;}printf("send success./n/r");return 0;}

编译程序用下列命令：

gcc -Wall simple-udpserver.c -o servergcc -Wall simple-udpclient.c -o client

运行程序用下列命令：

./server 127.0.0.1 7838./client 127.0.0.1 7838

UDP方式广播通讯
源代码变成下面的：

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;int sock;int addr_len;int len;char buff[128];int yes;/* 创建 socket */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");/* 设置通讯方式对广播，即本程序发送的一个消息，网络上所有主机均可以收到 */yes = 1;setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &yes, sizeof(yes));/* 唯一变化就是这一点了 *//* 设置对方地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);else {printf("消息必须有一个接收者！/n");exit(0);}/* 发送UDP消息 */addr_len = sizeof(s_addr);strcpy(buff, "hello i'm here");len = sendto(sock, buff, strlen(buff), 0,(struct sockaddr *) &s_addr, addr_len);if (len < 0) {printf("/n/rsend error./n/r");return 3;}printf("send success./n/r");return 0;}

编译这个程序用下列命令：