使用技术:

UDP ipv4 禁止本地回环 允许端口复用 超时等待 限制跳点 Echo

功能描述:

任意endpoint可主动发送多播,也可以收到信息后自动多播

前期准备:

开启操作系统多播广播功能,关闭系统防火墙,使用物理路由还需在路由开启广播多播功能

发送端和接收端运行不分先后 可无限复制多个接收端模拟集群

发送端:

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>#define MULTICAST_GROUP "239.0.0.1"
#define MULTICAST_PORT 55501
//发送端
int main()
{int server_sockfd;struct sockaddr_in server_sockaddr, multi_sockaddr, recv_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));memset(&multi_sockaddr, 0, sizeof(multi_sockaddr));memset(&recv_sockaddr, 0, sizeof(recv_sockaddr));socklen_t multi_sockaddr_len = sizeof(multi_sockaddr);socklen_t server_sockaddr_len = sizeof(server_sockaddr);socklen_t recv_sockaddr_len = sizeof(recv_sockaddr);ssize_t send_bytes, recv_bytes;char send_buf[1024] = "multicast from ubuntu";char recv_buf[1024] = {0};char recv_sockaddr_ip[INET_ADDRSTRLEN] = {0};// 用于加入多播网络struct ip_mreq mreq = {0};// 用于超时等待struct timeval tv = {0};tv.tv_sec = 1;tv.tv_usec = 0;// ipv4 udpserver_sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (server_sockfd == -1){perror("socket");}// 地址端口复用int optval = 1;setsockopt(server_sockfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));// 超时等待setsockopt(server_sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));// 限制跳点uint8_t ttl = 1;setsockopt(server_sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));// 禁止本地回环uint8_t loop = 0;setsockopt(server_sockfd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop));// 绑定接收端口,与多播端口一致,监听任意地址server_sockaddr.sin_family = AF_INET;server_sockaddr.sin_port = htons(MULTICAST_PORT);server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);if ((bind(server_sockfd, (struct sockaddr *)&server_sockaddr, server_sockaddr_len)) == -1){perror("bind");}// 加入多播组inet_pton(AF_INET, MULTICAST_GROUP, &mreq.imr_multiaddr.s_addr);mreq.imr_interface.s_addr = htonl(INADDR_ANY);setsockopt(server_sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));// 设置发送地址为多播组multi_sockaddr.sin_family = AF_INET;multi_sockaddr.sin_port = htons(MULTICAST_PORT);inet_pton(AF_INET, MULTICAST_GROUP, &multi_sockaddr.sin_addr.s_addr);while (1){sleep(1);send_bytes = sendto(server_sockfd, send_buf, strlen(send_buf),0, (struct sockaddr *)&multi_sockaddr, multi_sockaddr_len);if (send_bytes == -1){perror("sendto");}recv_bytes = recvfrom(server_sockfd, recv_buf, sizeof(recv_buf),0, (struct sockaddr *)&recv_sockaddr, &recv_sockaddr_len);if (recv_bytes == -1){perror("recvfrom");}inet_ntop(AF_INET, &recv_sockaddr.sin_addr, recv_sockaddr_ip, sizeof(recv_sockaddr_ip));// 收到消息则打印日志if (recv_bytes > 0){printf("INET_ADDR : %s PORT : %d Message : %s\n", recv_sockaddr_ip, ntohs(recv_sockaddr.sin_port), recv_buf);memset(recv_buf, 0, sizeof(recv_buf));memset(&recv_sockaddr, 0, sizeof(recv_sockaddr));}}close(server_sockfd);return 0;
}

接收端:

#define _GNU_SOURCE
#include <stdio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>#define MULTICAST_GROUP "239.0.0.1"
#define MULTICAST_PORT 55501
//接收端
int main()
{int server_sockfd;struct sockaddr_in server_sockaddr, multi_sockaddr, recv_sockaddr;memset(&server_sockaddr, 0, sizeof(server_sockaddr));memset(&multi_sockaddr, 0, sizeof(multi_sockaddr));memset(&recv_sockaddr, 0, sizeof(recv_sockaddr));socklen_t multi_sockaddr_len = sizeof(multi_sockaddr);socklen_t server_sockaddr_len = sizeof(server_sockaddr);socklen_t recv_sockaddr_len = sizeof(recv_sockaddr);ssize_t send_bytes, recv_bytes;char send_buf[1024] = "multicast from kali";char recv_buf[1024] = {0};char recv_sockaddr_ip[INET_ADDRSTRLEN] = {0};struct ip_mreq mreq = {0};server_sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (server_sockfd == -1){perror("socket");}// 禁止本地回环uint8_t loop = 0;setsockopt(server_sockfd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop));// 允许端口复用int optval = 1;setsockopt(server_sockfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));// 绑定地址为监听任意,绑定监听端口为多播端口server_sockaddr.sin_family = AF_INET;server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);server_sockaddr.sin_port = htons(MULTICAST_PORT);if ((bind(server_sockfd, (struct sockaddr *)&server_sockaddr, server_sockaddr_len)) == -1){perror("bind");}// 加入多播组mreq.imr_multiaddr.s_addr = inet_addr(MULTICAST_GROUP);mreq.imr_interface.s_addr = htonl(INADDR_ANY);setsockopt(server_sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));// 向多播组发送消息用multi_sockaddr.sin_family = AF_INET;multi_sockaddr.sin_port = htons(MULTICAST_PORT);inet_pton(AF_INET, MULTICAST_GROUP, &multi_sockaddr.sin_addr.s_addr);while (1){recv_bytes = recvfrom(server_sockfd, recv_buf, sizeof(recv_buf),0, (struct sockaddr *)&recv_sockaddr, &recv_sockaddr_len);if (recv_bytes == -1){perror("recvfrom");}inet_ntop(AF_INET, &recv_sockaddr.sin_addr, recv_sockaddr_ip, sizeof(recv_sockaddr_ip));// 如果收到了消息就打印if (recv_bytes > 0){printf("INET_ADDR : %s PORT : %d Message : %s\n", recv_sockaddr_ip, ntohs(recv_sockaddr.sin_port), recv_buf);memset(recv_buf, 0, sizeof(recv_buf));memset(&recv_sockaddr, 0, sizeof(recv_sockaddr));}sleep(1);// echo一条消息,也可主动发起send_bytes = sendto(server_sockfd, send_buf, strlen(send_buf),0, (struct sockaddr *)&multi_sockaddr, multi_sockaddr_len);if (send_bytes == -1){perror("sendto");}}close(server_sockfd);return 0;
}