需要使用套接字编程来编写使用TCP / IP协议的回显服务器，但是我与服务器的连接失败

如何解决需要使用套接字编程来编写使用TCP / IP协议的回显服务器，但是我与服务器的连接失败

两个程序都可以编译，并且我能够成功创建套接字，但是与服务器的连接失败。这基本上是一个TCP回显程序。 PS。我是新来的，所以IDK如何使用它，我没有太多的编程经验，所以对我来说没什么。

tcp echo client-1

tcp echo client-2

tcp echo server-1

tcp echo server-2

编译/运行服务器给我：服务器未完全实现... 编译/运行客户端给我：成功创建套接字。错误：与服务器的连接失败！

**// TCP echo client program**
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main (int argc,char* argv[ ])      // Three arguments to be checked later
{
    struct sockaddr_in servAddr;        // Server socket address data structure
    char *servIP = argv[1];             // Server IP address from command line
    int servPort = atoi(argv[2]);       // Server port number from command line
    char *message = argv[3];            // Message specified on the command line
    char buffer [512 + 1];
    char* ptr = buffer;
    int len; 
    int max_len = sizeof(buffer); 
    int sock_descrip; 

    // Check for correct number of command line arguments
    if(argc != 4) {                                               
        printf("tcp-echo-client [IP address] [Port] [Message]\n");                             
        exit (1);
    }                                                

    // Populate socket address for the server
    memset (&servAddr,sizeof(servAddr));        // Initialize data structure
    servAddr.sin_family = AF_INET;                  // This is an IPv4 address
    servAddr.sin_addr.s_addr = inet_addr(servIP);   // Server IP address
    servAddr.sin_port = servPort;                   // Server port number
    
    // Create a TCP socket stream
    int sock;
    if ((sock = socket (AF_INET,SOCK_STREAM,IPPROTO_TCP)) == -1) {
        printf("Error: socket creation failed!\n");
        exit (1);
    }
    else
        printf("Socket successfully created..\n"); 

    // Connect  to the server
    if ((connect (sock,(struct sockaddr*)&servAddr,sizeof(servAddr))) == -1) {
        printf("Error: connection to the server failed!\n");
        exit (1);
    }
     else
        printf("Connected to the server..\n"); 

    // Send data to the server...
    send(sock_descrip,message,strlen(message),0);
    int x;
    while ((x = recv(sock_descrip,ptr,max_len,0))>0)
    {
        ptr += x;
        max_len -= x;
        len += x;
    }
    buffer[len] = '\0';
    printf("Echoed string received: %s %c",buffer,*message);

    // Receive data back from the server..
        
    //  Loop while receiving data... 
    //      print data...
    //  end-while loop  

    // Close socket
    close (sock);
    
    // Stop program
    exit (0);
    
} // End main


**//TCP Echo server program**
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUFLEN  512                                         // Maximum length of buffer
#define PORT    9988                                        // Fixed server port number

int main (void)
{
    struct sockaddr_in server_address;                      // Data structure for server address
    struct sockaddr_in client_address;                      // Data structure for client address
    int client_address_len = 0;
    char buffer [512];
    char* ptr = buffer;
    int len;
    int max_len = BUFLEN; 
    int sock_descrip; 
        
    
    // Populate socket address for the server
    memset (&server_address,sizeof (server_address));   // Initialize server address data structure
    server_address.sin_family = AF_INET;                    // Populate family field - IPV4 protocol
    server_address.sin_port = PORT;                         // Set port number
    server_address.sin_addr.s_addr = INADDR_ANY;            // Set IP address to IPv4 value for loacalhost
        
    // Create a TCP socket; returns -1 on failure
    int listen_sock;
    if ((listen_sock = socket (AF_INET,IPPROTO_TCP)) == -1) {
        printf("Error: Listen socket failed!\n");
        exit (1);
    }

    // Bind the socket to the server address; returns -1 on failure
    if ((bind(listen_sock,(struct sockaddr *)&server_address,sizeof (server_address))) == -1) {
        printf("Error: binding failed!\n");
        exit (1);
    }
    
    printf("Server not fully implemented...\n");
    
    // Listen for connections...
    int wait_size; 
    if (listen(listen_sock,wait_size) == -1)
    {
        printf("Error: listening failed!\n");
        exit(1);
    }
    for(;;)
    {
        if(sock_descrip=accept(listen_sock,(struct sockaddr *)&client_address,&client_address_len) == -1)
        {
            printf("Error: accepting failed!\n");
            exit(1);
        }
        int x; 
        while ((x = recv(sock_descrip,0)) > 0)
        {
            ptr += x;
            max_len -= x; 
            len += x; 
        }
        send(sock_descrip,len,0);  
    }
    
    // Echo data back to the client...
        
    close (listen_sock);                                    // Close descriptor referencing server socket
    
} // End main

解决方法

您需要在作业周围加上括号：

if(
(sock_descrip=accept(listen_sock,(struct sockaddr *)&client_address,&client_address_len))
 == -1)