UDP套接字编程

• client

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdlib.h>

void usage(const char* proc)
{
        printf("usage:%s [local_ip] [local_port]\n",proc);
}

int main(int argc,char*argv[])
{
        if(argc != 3)
        {
            usage(argv[0]);
            return 1;
        }

        int sk = socket(AF_INET,SOCK_DGRAM,0);

        if(sk < 0)
        {
            perror("socket");
            return 2;
        }

        char buf[1024];
        struct sockaddr_in server;
        server.sin_family = PF_INET;
        server.sin_port = htons(atoi(argv[2]));
        server.sin_addr.s_addr = inet_addr(argv[1]);            
        socklen_t len = sizeof(server);

        while(1)
        {
            printf("Please Enter#:");
            fflush(stdout);

            ssize_t s = read(0,buf,sizeof(buf)-1);
            if(s > 0)
            {
                buf[s-1] = 0;
                sendto(sk,buf,sizeof(buf)-1,0,(struct sockaddr*)&server,len);
                s = recvfrom(sk,buf,sizeof(buf)-1,0,(struct sockaddr*)&server,&len);

                if(s>0)
                {
                    buf[s] = 0;
                    printf("server -> client: %s\n", buf);
                }
            }
        }
        return 0;
}

• server

nclude<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdlib.h>

void usage(const char* proc)
{
        printf("usage:%s [local_ip] [local_port]\n",proc);
}

int main(int argc,char*argv[])
{
        if(argc != 3)
        {
            usage(argv[0]);
            return 1;
        }

        int sk = socket(AF_INET,SOCK_DGRAM,0);
        if(sk < 0)
        {
            perror("socket");
            return 2;
        }

        struct sockaddr_in local;
        local.sin_family = PF_INET;
        local.sin_port = htons(atoi(argv[2]));
        local.sin_addr.s_addr =inet_addr(argv[1]);

        if(bind(sk,(struct sockaddr*)&local,sizeof(local))<0)
        { 
            perror("bind");
            return 3;
        }

        while(1)
        {
            char buf[1024];
            struct sockaddr_in client;
            socklen_t len = sizeof(client);

            ssize_t s = recvfrom(sk, buf, sizeof(buf)-1, 0, (struct sockaddr*)&client,&len);
            if(s > 0)
            {
                buf[s] = 0;
                printf("client -> server: %s\n",buf);
                sendto(sk,buf,strlen(buf), 0, (struct sockaddr*)&client, len);
            }
            else
            {
                close(sk);
                printf("client quit...\n");
                break;
            }
        }
        return 0;
}