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广播的发送端代码
#include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> int main(int agrc, char** argv){ int fd = socket(af_inet, sock_dgram, 0); int port = atoi(argv[1]); struct sockaddr_in addr; addr.sin_family = af_inet; addr.sin_port = htons(port); addr.sin_addr.s_addr = htonl(inaddr_any); bind(fd, (struct sockaddr*)&addr, sizeof(addr)); int n = 1; int ret = setsockopt(fd, sol_socket, so_broadcast, &n, sizeof(n)); struct sockaddr_in client; memset(&client, 0, sizeof(client)); client.sin_family = af_inet; client.sin_port = htons(6666); inet_pton(af_inet, "10.210.65.255", &client.sin_addr.s_addr); int cnt = 0; while(1){ char buf[64] = {0}; sprintf(buf, "count=%d", cnt++); int ret = sendto(fd, buf, sizeof buf, 0, (struct sockaddr*)&client, sizeof(client)); if(ret == -1){ perror("sendto -1"); } sleep(1); } }
必须用setsockopt函数开通套接字的组播权限。注意n的值不能为0.
由于广播的时候,必须指定接收端的端口号,所以接收端必须调用bind函数,显示的指定自己用的端口号。
接收广播发送信息的代码
#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> int main(int agrc, char** argv){ int fd = socket(af_inet, sock_dgram, 0); struct sockaddr_in addr; memset(&addr, 0, sizeof(addr)); addr.sin_family = af_inet; addr.sin_port = htons(6666); //addr.sin_addr.s_addr = htons(inaddr_any); inet_pton(af_inet, "0.0.0.0", &addr.sin_addr.s_addr); socklen_t len = sizeof(addr); bind(fd, (struct sockaddr*)&addr, sizeof(addr)); while(1){ char buf[64] = {0}; int ret = recvfrom(fd, buf, sizeof(buf), 0, null, null); write(stdout_fileno, buf, ret); sleep(1); } }
由于广播的时候,必须指定接收端的端口号,所以接收端必须调用bind函数,显示的指定自己用的端口号。
组播的ip介绍:
224.0.0.0~224.0.0.255为预留的组播地址(永久组地址),地址224.0.0.0保留不做分配,其它地址供路由协议使用; 224.0.1.0~224.0.1.255是公用组播地址,可以用于internet; 224.0.2.0~238.255.255.255为用户可用的组播地址(临时组地址),全网范围内有效; 239.0.0.0~239.255.255.255为本地管理组播地址,仅在特定的本地范围内有效。
组播发送端例子
#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> #include <net/if.h> int main(int agrc, char** argv){ int fd = socket(af_inet, sock_dgram, 0); int port = atoi(argv[1]); struct sockaddr_in addr; addr.sin_family = af_inet; addr.sin_port = htons(port); addr.sin_addr.s_addr = htonl(inaddr_any); bind(fd, (struct sockaddr*)&addr, sizeof(addr)); struct ip_mreqn n; inet_pton(af_inet, "239.0.0.10", &n.imr_multiaddr.s_addr);//组播地址 inet_pton(af_inet, "0.0.0.0", &n.imr_address.s_addr);//本机地址 n.imr_ifindex = if_nametoindex("enp0s3");//本机的通信用的网卡的物理地址,可以用ifconfig查看 int ret = setsockopt(fd, ipproto_ip, ip_multicast_if, &n, sizeof(n)); struct sockaddr_in client; memset(&client, 0, sizeof(client)); client.sin_family = af_inet; client.sin_port = htons(6666); inet_pton(af_inet, "239.0.0.10", &client.sin_addr.s_addr); int cnt = 0; while(1){ char buf[64] = {0}; sprintf(buf, "count=%d", cnt++); int ret = sendto(fd, buf, sizeof buf, 0, (struct sockaddr*)&client, sizeof(client)); if(ret == -1){ perror("sendto -1"); } sleep(1); } }
必须用setsockopt函数开通套接字的组播权限。发送端使用ipproto_ip和ip_multicast_if
函数if_nametoindex的作用是通过网卡的名字,取得网卡的mac地址。
组播接收端例子
#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> #include <net/if.h> int main(int agrc, char** argv){ int fd = socket(af_inet, sock_dgram, 0); struct sockaddr_in addr; memset(&addr, 0, sizeof(addr)); addr.sin_family = af_inet; addr.sin_port = htons(6666); //addr.sin_addr.s_addr = htons(inaddr_any); inet_pton(af_inet, "0.0.0.0", &addr.sin_addr.s_addr); socklen_t len = sizeof(addr); bind(fd, (struct sockaddr*)&addr, sizeof(addr)); struct ip_mreqn n; inet_pton(af_inet, "239.0.0.10", &n.imr_multiaddr.s_addr); inet_pton(af_inet, "0.0.0.0", &n.imr_address.s_addr); n.imr_ifindex = if_nametoindex("enp0s3"); int ret = setsockopt(fd, ipproto_ip, ip_add_membership, &n, sizeof(n)); while(1){ char buf[64] = {0}; int ret = recvfrom(fd, buf, sizeof(buf), 0, null, null); write(stdout_fileno, buf, ret); sleep(1); } }
必须用setsockopt函数把接收端的套接字加入到组播的组里。接收端使用ipproto_ip和ip_add_membership
由于组播的时候,必须指定接收端的端口号,所以接收端必须调用bind函数,显示的指定自己用的端口号
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