UDP Server and Client under Linux

// server.cpp

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

#define MAXLINE 80
#define SERV_PORT 8888

void do_echo(int sockfd, struct sockaddr *pcliaddr, socklen_t clilen)
{
    int n;
    socklen_t len;
    char mesg[MAXLINE];

    for(;;) {
        len = clilen;
        /* waiting for receive data */
        n = recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);
        /* sent data back to client */
        sendto(sockfd, mesg, n, 0, pcliaddr, len);
    }
}

int main(void)
{
    int sockfd;
    struct sockaddr_in servaddr, cliaddr;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0); /* create a socket */

    /* init servaddr */
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);

    /* bind address and port to socket */
    if(bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1) {
        perror("bind error");
        exit(1);
    }

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

    return 0;
}

// client.cpp

#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;
}

来源：https://blog.csdn.net/weixin_30838921/article/details/99792605

标签

linux系统

udp