《UNIX网络编程》UDP客户端服务器：消息回显

udp写的程序相比tcp简单一些，在socket()与bind()之后，不需要connect(),accept()等步骤，直接简化为了sendto()与recvfrom()。

编译运行同前面的tcp。

 

/*client_udp.c*/

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>



#define MAXLINE 4096

#define SERV_PORT 9877



void process(FILE *fp, int sockfd, const struct sockaddr *pservaddr,

        socklen_t servlen)

{

    int n;

    char send[MAXLINE], recv[MAXLINE];



    while (fgets(send, MAXLINE, fp) != NULL) {

        sendto(sockfd, send, strlen(send), 0, pservaddr, servlen);

        n = recvfrom(sockfd, recv, MAXLINE, 0, NULL, NULL);

        recv[n] = 0;

        fputs(recv, stdout);

    }

}



int main(int argc, char *argv[])

{

    int sockfd;

    struct sockaddr_in servaddr;



    if (argc != 2) {

        fprintf(stderr, "usage: client_udp <IP>\n");

        exit(1);

    }



    memset(&servaddr, 0, sizeof(servaddr));

    servaddr.sin_family = AF_INET;

    servaddr.sin_port = htons(SERV_PORT);

    inet_pton(AF_INET, argv[1], &servaddr.sin_addr);



    sockfd = socket(AF_INET, SOCK_DGRAM, 0);



    process(stdin, sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));



    exit(0);

}

 

/*server_udp.c*/

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>



#define MAXLINE 4096

#define    SERV_PORT 9877



void process(int sockfd, struct sockaddr *pcliaddr, socklen_t clilen)

{

    int n;

    socklen_t len;

    char mesg[MAXLINE];



    while (1) {

        len = clilen;

        n = recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);

        sendto(sockfd, mesg, n, 0, pcliaddr, len);

    }

}



int main(int argc, char *argv[])

{

    int sockfd;

    struct sockaddr_in servaddr, cliaddr;



    sockfd = socket(AF_INET, SOCK_DGRAM, 0);



    memset(&servaddr, 0, sizeof(servaddr));

    servaddr.sin_family = AF_INET;

    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    servaddr.sin_port = htons(SERV_PORT);



    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

    

    process(sockfd, (struct sockaddr *)&cliaddr, sizeof(cliaddr));

}