Question

如何使用不同的机器使用UPD客户端和服务器发送消息？我知道在同一台机器上使用这两个，我只需要编译它们并传递消息。但是用不同的机器怎么样？

此代码适用于UDP客户端。

/*
Simple udp client
Silver Moon (m00n.silv3r@gmail.com)
*/
#include<stdio.h> //printf
#include<string.h> //memset
#include<stdlib.h> //exit(0);
#include<arpa/inet.h>
#include<sys/socket.h>

#define SERVER "127.0.0.1"
#define BUFLEN 512 //Max length of buffer
#define PORT 8888 //The port on which to send data

void die(char *s)
{
    perror(s);
    exit(1);
}

int main(void)
{
    struct sockaddr_in si_other;
    int s, i, slen=sizeof(si_other);
    char buf[BUFLEN];
    char message[BUFLEN];

    if ( (s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
    {
            die("socket");
    }

    memset((char *) &si_other, 0, sizeof(si_other));
    si_other.sin_family = AF_INET;
    si_other.sin_port = htons(PORT);

    if (inet_aton(SERVER , &si_other.sin_addr) == 0)
    {
            fprintf(stderr, "inet_aton() failed\n");
            exit(1);
    }

    while(1)
    {
            printf("Enter message : ");
            gets(message);

            //send the message
            if (sendto(s, message, strlen(message) , 0 , (struct sockaddr *) &si_other, slen)==-1)
            {
            die("sendto()");
            }

            //receive a reply and print it
            //clear the buffer by filling null, it might have previously received data
            memset(buf,'\0', BUFLEN);
            //try to receive some data, this is a blocking call
            if (recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen) == -1)
            {
            die("recvfrom()");
            }

            puts(buf);
    }

    close(s);
    return 0;
}

此代码适用于UDP服务器。

 /* Simple udp server
 Silver Moon (m00n.silv3r@gmail.com) */
 #include<stdio.h> //printf
 #include<string.h> //memset
#include<stdlib.h> //exit(0);
#include<arpa/inet.h>
#include<sys/socket.h>
#define BUFLEN 512 //Max length of buffer
#define PORT 8888 //The port on which to listen for incoming data

void die(char *s)
{
    perror(s);
    exit(1);
 }

int main(void)
{
    struct sockaddr_in si_me, si_other;

    int s, i, slen = sizeof(si_other) , recv_len;
    char buf[BUFLEN];

    //create a UDP socket
    if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
    {
    die("socket");
    }

    // zero out the structure
    memset((char *) &si_me, 0, sizeof(si_me));

    si_me.sin_family = AF_INET;
    si_me.sin_port = htons(PORT);
    si_me.sin_addr.s_addr = htonl(INADDR_ANY);

    //bind socket to port
    if( bind(s , (struct sockaddr*)&si_me, sizeof(si_me) ) == -1)
    {
            die("bind");
    }

    //keep listening for data
    while(1)
    {
            printf("Waiting for data...");
            fflush(stdout);

            //try to receive some data, this is a blocking call
            if ((recv_len = recvfrom(s, buf, BUFLEN, 0, (struct   sockaddr *) &si_other, &slen)) == -1)
            {
                    die("recvfrom()");
            }

            //print details of the client/peer and the data received
            printf("Received packet from %s:%d\n", inet_ntoa(si_other.sin_addr),
            ntohs(si_other.sin_port));
            printf("Data: %s\n" , buf);

            //now reply the client with the same data
            if (sendto(s, buf, recv_len, 0, (struct sockaddr*) &si_other, slen) == -1)
            {
                    die("sendto()");
            }
    }

    close(s);
    return 0;
}

Answer 1

127.0.0.1是本地IP地址（分配给环回接口，参见下面的IP lo0 接口）。它适用于在同一主机/系统上作用于客户端服务器角色的差异进程进行通信。

您需要的是服务器系统上主接口的分配IP（如eth0 / en0等）。在MAC上，这看起来如下

#ifconfig -au
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
    ..
    inet 127.0.0.1 netmask 0xff000000 
    nd6 options=1<PERFORMNUD>
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ..
    inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
    nd6 options=1<PERFORMNUD>
    media: autoselect
    status: active

在上面的输出中，我使用 en0 上的IP地址192.168.1.2（对于要绑定的服务器），然后客户端可以通过网络连接到该IP。 / p>

UPD客户端和UDP服务器

1 个答案: