c - Socket编程中查找客户端和服务器的IP地址

Question

我已经开始练习套接字编程，并且我已经用 C 编写了客户端和服务器程序，并且它们通信良好。但是，我希望找到客户端和服务器的 IP 地址并在两个程序中打印它。

这是我的客户端代码...

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


struct node 
{
    int a;
    int b;
    char c[10];
};

int main(int argc, char const *argv[])
{
    int socketFD,port;
    struct sockaddr_in serverAddress, clientAddress;
    struct hostent *server;
    if (argc < 3) 
    {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    port = atoi(argv[2]);
    socketFD = socket(AF_INET, SOCK_STREAM, 0);
    if (socketFD < 0) error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) 
    {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    bzero((char *) &serverAddress, sizeof(serverAddress));
    serverAddress.sin_family = AF_INET;
    bcopy((char *)server->h_addr,(char *)&serverAddress.sin_addr.s_addr, server->h_length);
    serverAddress.sin_port = htons(port);

    clientAddress.sin_family=AF_INET;
    clientAddress.sin_port=htons(port);
    clientAddress.sin_addr.s_addr=htonl(INADDR_ANY);

    if (connect(socketFD,(struct sockaddr *)&serverAddress,sizeof(serverAddress)) < 0) error("ERROR connecting");

    struct node temp;
    temp.a=21;
    temp.b=32;
    temp.c[0]='T';
    temp.c[1]='E';
    temp.c[2]='M';
    temp.c[3]='P';
    sendto(socketFD, (void *) &temp, sizeof(temp), 0, (struct sockaddr*)&serverAddress, sizeof(serverAddress));
    printf("%s - %s", inet_ntoa(serverAddress.sin_addr), inet_ntoa(clientAddress.sin_addr));


    return 0;
}

这是我的服务器代码

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


struct node 
{
    int a;
    int b;
    char c[10];
};


int main(int argc, char const *argv[])
{
    if (argc < 2) 
    {
        fprintf(stderr,"ERROR, no port provided\n");
        exit(1);
    }
    int socketFD,port,clientFD,clientLen;
    struct sockaddr_in serverAddress, clientAddress;
    if((socketFD=socket(AF_INET,SOCK_STREAM,0))<0)
    {
        printf("Unable to create socket\n");
        return 1;
    }
    bzero((char*)&serverAddress,sizeof(serverAddress));
    port=atoi(argv[1]);
    serverAddress.sin_family=AF_INET;
    serverAddress.sin_port=htons(port);
    serverAddress.sin_addr.s_addr=htonl(INADDR_ANY);

    if((bind(socketFD,(struct sockaddr *)&serverAddress, sizeof(serverAddress)))<0)
    {
        printf("Error on binding\n");
        return 1;   
    }
    listen(socketFD,5);
    clientLen=sizeof(clientAddress);
    clientFD=accept(socketFD, (struct sockaddr *)&clientAddress, &clientLen);

    struct node temp;
    recvfrom(clientFD, (void *)&temp, sizeof(temp), 0, (struct sockaddr*)&clientAddress,  &clientLen); 

    printf("%d-%d-%s\n", temp.a, temp.b, temp.c);
    printf("%s - %s", inet_ntoa(serverAddress.sin_addr), inet_ntoa(clientAddress.sin_addr));
     close(clientFD);
    return 0;
}

我在服务器程序中面临的问题是，在输出中，它打印给结构变量的值，后跟一些未知字符，并且客户端和服务器的IP地址都打印为0.0.0.0..

问题是什么以及如何解决？

提前致谢

Answer 1

查看文档:

The inet_ntoa() function converts the Internet host address in, given in network byte order, to a string in IPv4 dotted-decimal notation. The string is returned in a statically allocated buffer, which subsequent calls will overwrite.