c++ - linux C/C++ socket程序为什么不出现ECONNRESET错误

Question

服务器端子函数:接收客户端数据，然后关闭套接字

server side child func:
                char line[1024];
                bzero(line,sizeof(line));
                int ret =  recv(fd,line,sizeof(line),0);
                if(ret > 0){
                        cout << line << endl;
                }else if(ret < 0){
                        cout << "recv error" << endl;
                }else if(ret == 0){
                        cout << "client close" << endl;
                        break;
                }
                shutdown(fd,SHUT_WR);

客户端主要功能

char line[] = "ds2d2d2d2d21dwq";
        send(sockfd,line,sizeof(line),0); //send to server
        //server side the child func has exit
        sleep(20);
        cout << "write to server" << endl;
        //write to server again
        ret = send(sockfd,line,sizeof(line),0);
        perror("write...."); //write success
        //according to unp book ,the server has send the RST msg to client
        bzero(line,sizeof(line));
        sleep(5);
        //recv should return error and the error code should ECONNRESET 
        //but not appear , the recv success return 0(EOF)
        //then execute recv success return 0(EOF)
        ret = recv(sockfd,line,sizeof(line),0);
        cout << ret <<line << endl;
        perror("recv....");
        ret = recv(sockfd,line,sizeof(line),0);
        perror("recv....");

不知道这样对不对？内核改进。我发现recv系统没有ECONNRESET错误代码

Answer 1

从“man recv”页面:

RETURN VALUES

  These calls return the number of bytes received, or -1 if an error
  occurred.

  For TCP sockets, the return value 0 means the peer has closed its half
  side of the connection.

因此，当服务器关闭 TCP 连接时，客户端上的 recv() 预计将开始返回零(当然，只有在它完成返回服务器 send() 处理的任何数据之后)