server.c

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

#define UDP_PORT  8080
#define UDP_BUF_SIZE  100
#define UDP_SERV_IP_ADDR  "192.168.100.178"
#define UDP_CLIENT_IP_ADDR  "192.168.100.51"


int
main(void)
{
    int fd = -1;
    int len = 0;
    int res = 0;
    int i;
    struct sockaddr_in sin;

    /*  建立socket_fd   */
    if((fd = socket( AF_INET, SOCK_DGRAM , 0
 
)) < 0)
    {
        printf("*******SOCKET********\n");
        return -1;
    }
    
    /*  允許繫結地址快速重用   */
    int b_reuse = 1;
    setsockopt( fd, SOL_SOCKET, SO_REUSEADDR, &b_reuse, sizeof(b_reuse));

    /*   填充struct sockaddr_in 結構體變數   */
    bzero( &sin, sizeof(sin));
    sin.sin_family 
 
= AF_INET;
    sin.sin_port = htons(UDP_PORT);
    /*  讓伺服器程式能繫結在任意的IP上    */
#if    1
    sin.sin_addr.s_addr = htonl(INADDR_ANY);
#else
    if((inet_pton(AF_INET, UDP_SERV_IP_ADDR, (void *)&sin.sin_addr)) < 0)
    {
        printf("******INET_PTON*******\n");
        return -1;
    }
#endif
    /*  繫結  */
    if(bind (fd, (struct sockaddr *)&sin, sizeof(sin)) <0 )
    {
        printf("*******bind*******\n");
        return -1;
    }


    char buf[UDP_BUF_SIZE];
    struct sockaddr_in cin;
    socklen_t addrlen = sizeof(cin);

    while(1)
    {
        bzero(buf ,UDP_BUF_SIZE);

        len = recvfrom(fd, buf, UDP_BUF_SIZE-1,0,(struct sockaddr*)&cin, &addrlen);

        if(len > 0)
        {
            char ipv4_addr[16];
            if(!inet_ntop(AF_INET, (void *)&cin.sin_addr, ipv4_addr, sizeof(cin)))
            {
                printf("*******inet_ntop********\n");
                return -1;
            }

            printf("********recv from (%s:%d), date:",ipv4_addr, ntohs(sin.sin_port));
            
            for(i = 0;i< len;i++)
              printf("%02X ", buf[i]);
            printf("\n");
        }        
    }

    close(fd);

    return 0;
}