Linux基础——socket的UDP实现

与TCP连接相差不多，UDP同样需要套接字socket产生。

注意:UDP中需要知道对方的IP及port，这样才能正确的传送数据。

UDP服务器实现代码如下:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#define IP "192.168.0.124"
#define PORT 10000
int main(int argc,char *argv[])
{
    int fd;
    if((fd = socket(AF_INET,SOCK_DGRAM,0))==-1)
    {
        perror("socket");
        exit(1);
    }
    struct sockaddr_in addr,addr_client;
    memset(&addr,0,sizeof(addr));
    memset(&addr_client,0,sizeof(addr_client));
    int len = sizeof(addr_client);
    addr.sin_family=AF_INET;
    addr.sin_port=htons(PORT);
    addr.sin_addr.s_addr=inet_addr(IP);
    if(-1 == bind(fd,(struct sockaddr*)&addr,sizeof(addr)))
    {
        perror("bind");
        exit(1);
    }
    char buf[128];
    memset(buf,0,128);
    recvfrom(fd,buf,128,0,(struct sockaddr*)&addr_client,&len);
                printf("recv : %s from  %s : %d
",buf,inet_ntoa(addr_client.sin_addr),ntohs(addr_client.sin_port));
        if(fork()>0)
        {
            while(memset(buf,0,128),recvfrom(fd,buf,128,0,(struct sockaddr*)&addr_client,&len)>0)
                printf("recv : %s from  %s : %d
",buf,inet_ntoa(addr_client.sin_addr),ntohs(addr_client.sin_port));
            exit(0);
        }
        while(memset(buf,0,128),fgets(buf,128,stdin)!=NULL)
            sendto(fd,buf,strlen(buf),0,(struct sockaddr*)&addr_client,sizeof(addr));
        wait(NULL);
    close(fd);
    return 0;
}

客户端实现代码如下:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define IP "192.168.0.173"
#define PORT 9999
int main(int argc,char *argv[])
{
    int fd;
    if((fd = socket(AF_INET,SOCK_DGRAM,0))==-1 )
    {
        perror("socket");
        exit(1);
    }
    struct sockaddr_in addr;
    memset(&addr,0,sizeof(addr));
    int len = sizeof(addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(PORT);
    addr.sin_addr.s_addr = inet_addr(IP);
    char buf[128];
    int sendn;
        if(fork()==0)
        {
            while(memset(buf,0,128),fgets(buf,128,stdin)!=NULL)
                sendto(fd,buf,strlen(buf),0,(struct sockaddr*)&addr,len);
            exit(0);
        }
        while(memset(buf ,0 ,128),recvfrom(fd,buf,128,0,(struct sockaddr*)&addr,&len)>0)
            printf("recv : %s  form : %s:%d
",buf,inet_ntoa(addr.sin_addr),ntohs(addr.sin_port));
        wait(NULL);
    close(fd);
    return 0;
}