C中使用套接字和tcp的服务器客户端程序

Question

我编写了一个程序，用于使用套接字编程在服务器和客户端之间进行简单的文本聊天。服务器端运行正常，因为它正在侦听，但是当我运行客户端程序时，它运行但没有显示输出，这意味着如果我在客户端输入，服务器端不会显示任何内容。为什么我没有收到客户端的任何响应？

    /****************** CLIENT CODE ****************/

        #include <stdio.h>
        #include <sys/socket.h>
        #include <netinet/in.h>
        #include <string.h>

        int main(){
  int clientSocket,n;
  char buffer[256];
  struct sockaddr_in serverAddr;
  socklen_t addr_size;

  /*---- Create the socket. The three arguments are: ----*/
  /* 1) Internet domain 2) Stream socket 3) Default protocol (TCP in this case) */
  clientSocket = socket(PF_INET, SOCK_STREAM, 0);

  /*---- Configure settings of the server address struct ----*/
  /* Address family = Internet */
  serverAddr.sin_family = AF_INET;
  /* Set port number, using htons function to use proper byte order */
  serverAddr.sin_port = htons(7891);
  /* Set IP address to localhost */
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
  /* Set all bits of the padding field to 0 */
  memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);  

  /*---- Connect the socket to the server using the address struct ----*/
  addr_size = sizeof serverAddr;
  connect(clientSocket, (struct sockaddr *) &serverAddr, addr_size);

  if (connect(clientSocket,(struct sockaddr *) &serverAddr,sizeof(serverAddr)) < 0) 
        error("ERROR connecting");
    printf("Please enter the message: ");
    bzero(buffer,256);
    fgets(buffer,255,stdin);
    n = write(clientSocket,buffer,strlen(buffer));
    if (n < 0) 
         error("ERROR writing to socket");
    bzero(buffer,256);
    n = read(clientSocket,buffer,255);
    if (n < 0) 
         error("ERROR reading from socket");
    printf("%s\n",buffer);
    close(clientSocket);
  /*---- Read the message from the server into the buffer ----*/
  //recv(clientSocket, buffer, 1024, 0);

  /*---- Print the received message ----*/
  //printf("Data received: %s",buffer);   

  return 0;
}


/****************** SERVER CODE ****************/

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main(){
  int welcomeSocket, newSocket;
  char buffer[256];
  int n;
  struct sockaddr_in serverAddr;
  struct sockaddr_storage serverStorage;
  socklen_t addr_size;

  /*---- Create the socket. The three arguments are: ----*/
  /* 1) Internet domain 2) Stream socket 3) Default protocol (TCP in this case) */
  welcomeSocket = socket(PF_INET, SOCK_STREAM, 0);

  /*---- Configure settings of the server address struct ----*/
  /* Address family = Internet */
  serverAddr.sin_family = AF_INET;
  /* Set port number, using htons function to use proper byte order */
  serverAddr.sin_port = htons(7891);
  /* Set IP address to localhost */
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
  /* Set all bits of the padding field to 0 */
  memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);  

  /*---- Bind the address struct to the socket ----*/
  bind(welcomeSocket, (struct sockaddr *) &serverAddr, sizeof(serverAddr));

  /*---- Listen on the socket, with 5 max connection requests queued ----*/
  if(listen(welcomeSocket,5)==0)
    printf("Listening\n");
  else
    printf("Error\n");

  /*---- Accept call creates a new socket for the incoming connection ----*/
  addr_size = sizeof serverStorage;
  newSocket = accept(welcomeSocket, (struct sockaddr *) &serverStorage, &addr_size);

  /*---- Send message to the socket of the incoming connection ----*/
  bzero(buffer,256);
     n = read(welcomeSocket,buffer,255);
     if (n < 0) error("ERROR reading from socket");
     printf("Here is the message: %s\n",buffer);
     n = write(welcomeSocket,"I got your message",18);
if (n < 0) error("ERROR reading from socket");
     printf("Here is the message: %s\n",buffer);
     n = write(welcomeSocket,"I got your message",18);
     if (n < 0) error("ERROR writing to socket");
     close(newSocket);
     close(welcomeSocket);

  return 0;
}

Answer 1

在您的服务器代码中，read() 应该使用从 accept() 返回的套接字描述符，而不是从对 socket() 的调用返回的套接字描述符。所以尝试使用newSocket 而不是welcomeSocket 阅读。

n = read(newSocket,buffer,255);