udp_server.c

UDP服务器端数据传输,是在LINUX下使用C语言进行编程

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

#define SOCK_PORT 7838
int main(int argc, char **argv)
{
    struct sockaddr_in s_addr,s_addr1;
    struct sockaddr_in c_addr,c_addr1;
    struct hostent *host;
    int sock,sock1;
    socklen_t addr_len,addr_len1;
    int len;
    char buff[128];
    int yes=1;
    /*create socket */
    if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        perror("socket");
        exit(errno);
    } else
        printf("create socket.\n\r");
    
    memset(&s_addr, 0, sizeof(struct sockaddr_in));
    /*Establishment address and port information */
    s_addr.sin_family = AF_INET;
    s_addr.sin_port = htons(SOCK_PORT);
    s_addr.sin_addr.s_addr = INADDR_ANY; 
    printf("%d, %d, %d, %d\n\r", s_addr.sin_family, 
    ntohs(s_addr.sin_port), 
    s_addr.sin_addr.s_addr,
    sock);
    
    
    /* bind address and the port information */
    if ((bind(sock, (struct sockaddr *) &s_addr, sizeof(s_addr))) == -1) {
        perror("bind");
        exit(errno);
    } else
        printf("bind address to socket.\n\r");
    
    /* Circulation receive data */
    addr_len = sizeof(c_addr);
    while (1) {
        len = recvfrom(sock, buff, sizeof(buff) - 1, 0,
        (struct sockaddr *) &c_addr, &addr_len);
        if (len < 0) {
        perror("recvfrom");
        exit(errno);
        }
    
        buff[len] = '\0';
        printf("Receives from %s:%dNews:%s\n\r",
        inet_ntoa(c_addr.sin_addr), ntohs(c_addr.sin_port), buff);
        
        if ((sock1 = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        perror("socket1");
        exit(errno);
        } else
        printf("create socket1.\n\r");
        
    
        memset(&s_addr1, 0, sizeof(struct sockaddr_in));
        s_addr1.sin_family = AF_INET;
        s_addr1.sin_port = htons(SOCK_PORT-1);
        //s_addr1.sin_addr.s_addr =*((struct in_addr*)host->h_addr_list); 
        
        memset(&c_addr1,0,sizeof(struct sockaddr_in));
        c_addr1.sin_family = AF_INET;
        c_addr1.sin_port =htons(SOCK_PORT);
        c_addr1.sin_addr.s_addr = inet_addr(inet_ntoa(c_addr.sin_addr));

        addr_len1 = sizeof(s_addr1);
        memset(buff,0x00,sizeof(buff));
        strcpy(buff, "hello i'm here2 -----------\n\r");
        len = sendto(sock1, buff, strlen(buff), 0,
        (struct sockaddr *) &c_addr1, addr_len1);
        if (len < 0) {
        printf("\n\rsend error.\n\r");
        return 3;
        }
    }  
    return 0;
}