client.c

用户数据报协议的程序源码

#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
 
#define MAXLINE         80
#define SERV_PORT       8888
 
void do_cli(FILE *fp, int sockfd, struct sockaddr *pservaddr, socklen_t servlen)
{
        int n;
        char sendline[MAXLINE], recvline[MAXLINE + 1];
 
        /* connect to server */
        if(connect(sockfd, (struct sockaddr *)pservaddr, servlen) == -1)
        {
                perror("connect error");
                exit(1);
        }
 
        while(fgets(sendline, MAXLINE, fp) != NULL)
        {
                /* read a line and send to server */
                write(sockfd, sendline, strlen(sendline));
                /* receive data from server */
                n = read(sockfd, recvline, MAXLINE);
                if(n == -1)
                {
                        perror("read error");
                        exit(1);
                }
                recvline[n] = 0;        /* terminate string */
                fputs(recvline, stdout);
        }
}
 
int main(int argc, char **argv)
{
        int sockfd;
        struct sockaddr_in servaddr;

        /* check args */
        if(argc != 2)
        {
                printf("usage: udpclient <IPaddress>\n");
                exit(1);
        }

        /* init servaddr */
        bzero(&servaddr, sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_port = htons(SERV_PORT);
        if(inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
        {
                printf("[%s] is not a valid IPaddress\n", argv[1]);
                exit(1);
        }
 
        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
 
        do_cli(stdin, sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
 
        return 0;
}