转载地址1:https://www.cnblogs.com/wanghao-boke/p/11443724.html
转载地址2:https://www.cnblogs.com/wanghao-boke/p/11443731.html
广播
广播是在局域网之间的一对多的通信方式,使用的udp协议。
/***
client.c
***/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define SERVER_PORT 8000
#define MAXLINE 4096
#define CLIENT_PORT 9000
int main(int argc, char *argv[])
{
struct sockaddr_in localaddr;
int confd;
ssize_t len;
char buf[MAXLINE];
//1.创建一个socket
confd = socket(AF_INET, SOCK_DGRAM, 0);
//2.初始化本地端地址
bzero(&localaddr, sizeof(localaddr));
localaddr.sin_family = AF_INET;
inet_pton(AF_INET, "0.0.0.0" , &localaddr.sin_addr.s_addr);
localaddr.sin_port = htons(CLIENT_PORT);
int ret = bind(confd, (struct sockaddr *)&localaddr, sizeof(localaddr)); //显示绑定不能省略
if (ret == 0)
printf("...bind ok...\n");
while (1) {
len = recvfrom(confd, buf, sizeof(buf), 0, NULL, 0);
write(STDOUT_FILENO, buf, len);
}
close(confd);
return 0;
}
多播
多播又称组播,组播组可以是永久的也可以是临时的。组播组地址中,有一部分由官方分配的,称为永久组播组。永久组播组保持不变的是它的ip地址,组中的成员构成可以发生变化。永久组播组中成员的数量都可以是任意的,甚至可以为零。那些没有保留下来供永久组播组使用的ip组播地址,可以被临时组播组利用。
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;欲使用需申请。
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。
服务端
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <net/if.h>
#define SERVER_PORT 6666
#define CLIENT_PORT 9000
#define MAXLINE 1500
#define GROUP "239.0.0.2"
int main(void)
{
int sockfd, i ;
struct sockaddr_in serveraddr, clientaddr;
char buf[MAXLINE] = "itcast\n";
char ipstr[INET_ADDRSTRLEN]; /* 16 Bytes */
socklen_t clientlen;
ssize_t len;
struct ip_mreqn group;
/* 构造用于UDP通信的套接字 */
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
bzero(&serveraddr, sizeof(serveraddr));
serveraddr.sin_family = AF_INET; /* IPv4 */
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY); /* 本地任意IP INADDR_ANY = 0 */
serveraddr.sin_port = htons(SERVER_PORT);
bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
/*设置组地址*/
inet_pton(AF_INET, GROUP, &group.imr_multiaddr);
/*本地任意IP*/
inet_pton(AF_INET, "0.0.0.0", &group.imr_address);
/* eth0 --> 编号 命令:ip ad */
group.imr_ifindex = if_nametoindex("eth0");
setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_IF, &group, sizeof(group));
/*构造 client 地址 IP+端口 */
bzero(&clientaddr, sizeof(clientaddr));
clientaddr.sin_family = AF_INET; /* IPv4 */
inet_pton(AF_INET, GROUP, &clientaddr.sin_addr.s_addr);
clientaddr.sin_port = htons(CLIENT_PORT);
while (1) {
//fgets(buf, sizeof(buf), stdin);
sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&clientaddr, sizeof(clientaddr));
sleep(1);
}
close(sockfd);
return 0;
}
客户端
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <net/if.h>
#define SERVER_PORT 6666
#define MAXLINE 4096
#define CLIENT_PORT 9000
#define GROUP "239.0.0.2"
int main(int argc, char *argv[])
{
struct sockaddr_in serveraddr, localaddr;
int confd;
ssize_t len;
char buf[MAXLINE];
/* 定义组播结构体 */
struct ip_mreqn group;
confd = socket(AF_INET, SOCK_DGRAM, 0);
//初始化本地端地址
bzero(&localaddr, sizeof(localaddr));
localaddr.sin_family = AF_INET;
inet_pton(AF_INET, "0.0.0.0" , &localaddr.sin_addr.s_addr);
localaddr.sin_port = htons(CLIENT_PORT);
bind(confd, (struct sockaddr *)&localaddr, sizeof(localaddr));
/*设置组地址*/
inet_pton(AF_INET, GROUP, &group.imr_multiaddr);
/*本地任意IP*/
inet_pton(AF_INET, "0.0.0.0", &group.imr_address);
/* eth0 --> 编号 命令:ip ad */
group.imr_ifindex = if_nametoindex("eth0");
/*设置client 加入多播组 */
setsockopt(confd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &group, sizeof(group));
while (1) {
len = recvfrom(confd, buf, sizeof(buf), 0, NULL, 0);
write(STDOUT_FILENO, buf, len);
}
close(confd);
return 0;
}