Linux Socket 学习笔记11-一个基于UDP协议的实例

/*
 * server :
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
 
 
int
main(int argc,char **argv) {
    int z;
    char *srvr_addr = NULL;
    struct sockaddr_in adr_inet;/* AF_INET */
    struct sockaddr_in adr_clnt;/* AF_INET */
    int len_inet;               /* length  */
    int s;                       /* Socket */
    char dgram[512];        /* Recv buffer */
    char dtfmt[512];   /* Date/Time Result */
 
    srvr_addr = "127.0.0.23";
 
 
    /*
     * Create a UDP socket to use :
     */
    s = socket(AF_INET,SOCK_DGRAM,0);
 
 
    /*
     * Create a socket address, for use
     * with bind(2) :
     */
    memset(&adr_inet,0,sizeof adr_inet);
    adr_inet.sin_family = AF_INET;
    adr_inet.sin_port = htons(9090);
    adr_inet.sin_addr.s_addr =
        inet_addr(srvr_addr);
 
 
    len_inet = sizeof adr_inet;
 
    /*
     * Bind a address to our socket, so that
     * client programs can contact this
     * server:
     */
    z = bind(s,
        (struct sockaddr *)&adr_inet,
        len_inet);
 
 
    /*
     * Now wait for requests:
     */
    for (;;) {
        /*
         * Block until the program receives a
         * datagram at our address and port:
         */
        len_inet = sizeof adr_clnt;
        z = recvfrom(s,                /* Socket */
            dgram,           /* Receiving buffer */
            sizeof dgram,   /* Max recv buf size */
            0,              /* Flags: no options */
            (struct sockaddr *)&adr_clnt,/* Addr */
            &len_inet);    /* Addr len, in & out */
 
 
        /*
         * Process the request :
         */
        dgram[z] = 0;          /* null terminate */
 
 
 
	printf("%s:%sn",inet_ntoa(adr_clnt.sin_addr),dgram);
 
 
	fputs("Enter:",stdout);
        if ( !fgets(dtfmt,sizeof dtfmt,stdin) )
            break;
 
 
        z = sendto(s,   /* Socket to send result */
            dtfmt, /* The datagram result to snd */
            strlen(dtfmt), /* The datagram lngth */
            0,              /* Flags: no options */
            (struct sockaddr *)&adr_clnt,/* addr */
            len_inet);  /* Client address length */
 
    }
 
    /*
     * Close the socket and exit:
     */
    close(s);
    return 0;
}

/*
 * client :
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
 
 
int
main(int argc,char **argv) {
    int z;
    int x;
    char *srvr_addr = NULL;
    struct sockaddr_in adr_srvr;/* AF_INET */
    struct sockaddr_in adr;     /* AF_INET */
    int len_inet;               /* length  */
    int s;                       /* Socket */
    char dgram[512];        /* Recv buffer */
 
    srvr_addr = "127.0.0.23";
 
    /*
     * Create a socket address, to use
     * to contact the server with:
     */
    memset(&adr_srvr,0,sizeof adr_srvr);
    adr_srvr.sin_family = AF_INET;
    adr_srvr.sin_port = htons(9090);
    adr_srvr.sin_addr.s_addr =
    inet_addr(srvr_addr);
 
 
 
    len_inet = sizeof adr_srvr;
 
    /*
     * Create a UDP socket to use :
     */
    s = socket(AF_INET,SOCK_DGRAM,0);
 
 
    for (;;) {
        /*
         * Prompt user for a date format string:
         */
        fputs("Enter:",stdout);
        if ( !fgets(dgram,sizeof dgram,stdin) )
            break;                        /* EOF */
 
        z = strlen(dgram);
        if ( z > 0 && dgram[--z] == 'n' )
            dgram[z] = 0;   /* Stomp out newline */
 
        /*
         * Send format string to server:
         */
        z = sendto(s,   /* Socket to send result */
            dgram, /* The datagram result to snd */
            strlen(dgram), /* The datagram lngth */
            0,              /* Flags: no options */
            (struct sockaddr *)&adr_srvr,/* addr */
            len_inet);  /* Server address length */
 
 
        /*
         * Wait for a response :
         */
        x = sizeof adr;
        z = recvfrom(s,                /* Socket */
            dgram,           /* Receiving buffer */
            sizeof dgram,   /* Max recv buf size */
            0,              /* Flags: no options */
            (struct sockaddr *)&adr,     /* Addr */
            &x);           /* Addr len, in & out */
 
 
        dgram[z] = 0;          /* null terminate */
 
        printf("%s:%sn",
            inet_ntoa(adr.sin_addr),
            dgram);
    }
 
    /*
     * Close the socket and exit:
     */
    close(s);
 
    return 0;
}