c++ - 如何在 C/C++ 中关闭特定客户端的套接字？

Question

服务器连接到几个客户端。客户端向服务器发送消息再见。如果服务器关闭它的套接字，它就会失去与其他客户端的连接。我是否需要通知服务器客户端已关闭以及如何在以下简单示例中为特定客户端关闭它:

服务器:

#include "wrappers.h"
int main(){

  unsigned int Sockfd, NewSockfd, ClntLen;
  sockaddr_in ClntAddr, ServAddr;
  int Port = SERV_TCP_PORT;
  char String[MAX_SIZE];
  int Len;

  // open a TCP socket (an Internet stream socket)
  Sockfd = Socket(AF_INET, SOCK_STREAM, 0); // socket() wrapper fn

  // bind the local address, so that the client can send to server
  memset((char*)&ServAddr, 0, sizeof(ServAddr));
  ServAddr.sin_family = AF_INET;
  ServAddr.sin_addr.s_addr = htonl(INADDR_ANY);
  ServAddr.sin_port = htons(Port);

  Bind(Sockfd, (sockaddr*) &ServAddr, sizeof(ServAddr));

  // listen to the socket
  Listen(Sockfd, 5);

  for(;;){
     // wait for a connection from a client; this is an iterative server
     ClntLen = sizeof(ClntAddr);
     NewSockfd = Accept(Sockfd, (sockaddr*)&ClntAddr, &ClntLen);

     if(NewSockfd < 0){
        perror("Can't bind local address!");
     }

     // read a message from the client
     Len = read(NewSockfd, String, MAX_SIZE);
     String[Len] = 0;// make sure it's a proper string
     printf("%s\n", String);


     write(NewSockfd, "hello", sizeof("hello"));
     cout<<"wrote to client"<<endl;

     close(NewSockfd);
  }
}

客户:

#include "wrappers.h"

int main()
{
  int Sockfd;
  sockaddr_in ServAddr;
  char ServHost[] = "localhost";
  hostent *HostPtr;
  int Port = SERV_TCP_PORT;
  int BuffSize = 0;

  // get the address of the host
  HostPtr = Gethostbyname(ServHost);

  if(HostPtr->h_addrtype !=  AF_INET){
     perror("Unknown address type!");
     exit(1);
  }

  memset((char *) &ServAddr, 0, sizeof(ServAddr));
  ServAddr.sin_family = AF_INET;
  ServAddr.sin_addr.s_addr = ((in_addr*)HostPtr->h_addr_list[0])->s_addr;
  ServAddr.sin_port = htons(Port);
  bool loop = true;

  int i= 0;
  while(loop){


      // open a TCP socket
      Sockfd = Socket(AF_INET, SOCK_STREAM, 0);

      // connect to the server
      Connect(Sockfd, (sockaddr*)&ServAddr, sizeof(ServAddr));


      if(i>5){
          loop = false;
      }
      i++;
      // write a message to the server
      write(Sockfd, "hello world", sizeof("hello world"));

      char String[10];
      int Len = read(Sockfd, String, MAX_SIZE);
      String[Len] = 0;// make sure it's a proper string
      printf("%s === \n", String);

  }


  close(Sockfd);
}

Answer 1

如果client 套接字关闭，您将从read 得到服务器端的返回值0。这是客户端连接结束的指示。

如果你尝试write到这样的socket，你会收到SIGPIPE信号，write会返回错误errno 设置为 EPIPE(“Broken Pipe”)。