Linux c udp广播

1、对比

服务端：
需要利用这个函数开发套接字的发广播权限，并且需要客户端地址绑定为广播地址
setsocket(sockfd,SOL_SOCKET,SO_BROADCAST,&flag,sizeof(flag));

客户端没有什么变化

2、代码

2.1、服务端

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <net/if.h>

#define PORT 9999
#define CLIENT_PORT 8888
void sys_perr(const char* str)
{
    perror(str);
    exit(1);
}

#define SER_PORT 9999

int main()
{
    int fd = socket(AF_INET,SOCK_DGRAM,0);
    struct sockaddr_in ser_addr,cli_addr;
    ser_addr.sin_family = AF_INET;
    ser_addr.sin_port = htons(SER_PORT);
    ser_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    bind(fd,(struct sockaddr*)&ser_addr,sizeof(ser_addr));

    int opt = 1;
    setsockopt(fd,SOL_SOCKET,SO_BROADCAST,&opt,sizeof(opt));    // 给当前socket广播权限

    cli_addr.sin_family = AF_INET;
    cli_addr.sin_port = htons(CLIENT_PORT);
    inet_pton(AF_INET,"本地广播地址",&cli_addr.sin_addr.s_addr);
    int i = 0;
    char buf[1024];
    while (1)
    {
        sprintf(buf,"hello %d\n",i++);
        printf("buf=%s\n",buf);
        int len = sendto(fd,buf,strlen(buf)+1,0,(struct sockaddr*)&cli_addr,sizeof(cli_addr));
        printf("%d\n",len);
        sleep(1);
    }

    return 0;
}

2.2、客户端

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <net/if.h>

#define CLIENT_PORT 8888
void sys_perr(const char* str)
{
    perror(str);
    exit(1);
}

#define SER_PORT 9999

int main()
{
    int fd = socket(AF_INET,SOCK_DGRAM,0);
    struct sockaddr_in cli_addr;
    cli_addr.sin_family = AF_INET;
    cli_addr.sin_port = htons(CLIENT_PORT);
    inet_pton(AF_INET,"0.0.0.0",&cli_addr.sin_addr.s_addr);
    bind(fd,(struct sockaddr*)&cli_addr,sizeof(cli_addr));
    char buf[1024];
    while (1)
    {
        int len = recvfrom(fd,buf,sizeof(buf),0,NULL,0);
        printf("%d\n",len);
        write(STDOUT_FILENO,buf,len);
    }
    
    


    return 0;
}