Я использую функцию select () и пытаюсь запустить несколько клиентов.Каждый клиент - это независимый процесс.Но сервер, кажется, интересуется только последними подключенными клиентами.
Это мой client.c
#include <stdio.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include "mpi.h"
#define PORT 8888
int main(int argc, char const *argv[])
{
/* Starting the MPI verion from here */
// Initialize the MPI environment
MPI_Init(NULL, NULL);
// Get the number of generators to be run in parallel
int number_of_clients;
MPI_Comm_size(MPI_COMM_WORLD, &number_of_clients);
// Get the rank of each generator
int client_rank;
MPI_Comm_rank(MPI_COMM_WORLD, &client_rank);
struct sockaddr_in address;
int sock = 0, valread;
struct sockaddr_in serv_addr;
char *message1 = "Hello from client";
char *message2 = "I am disconnecting";
char buffer[1024] = {0};
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Socket creation error \n");
return -1;
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(PORT);
// Convert IPv4 and IPv6 addresses from text to binary form
if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0)
{
printf("\nInvalid address/ Address not supported \n");
return -1;
}
if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\nConnection Failed \n");
return -1;
}
send(sock , message1 , strlen(message1) , 0 );
printf("Hello message sent from client_rank %d\n",client_rank);
valread = read( sock , buffer, 1024);
buffer[valread] = '\0';
printf("The message received from server by client_rank %d is %s\n", client_rank, buffer );
send(sock, message2, strlen(message2), 0);
printf("The message sent again from client_rank %d is %s\n", client_rank, message2);
close(sock);
// Finalize the MPI environment.
MPI_Finalize();
/*Ending the parallel version here*/
return 0;
}
Это мой server.c
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h> //close
#include <sys/types.h>
#include <sys/time.h> //FD_SET, FD_ISSET, FD_ZERO macros
#define PORT 8888
int main(int argc, char const *argv[])
{
int totalconnections = 0;
int server_fd, new_socket, valread;
struct sockaddr_in address, cli_addr;;
int opt = 1;
int addrlen = sizeof(address);
char buffer[1024] = {0};
char *hello = "Hello from server";
socklen_t clilen;
int closed_connections = 0;
int client_socket[3] , max_clients = 2 , activity, i , sd, max_sd;
int connected_clients = 0;
fd_set readfds;
//initialise all client_socket[] to 0 so not checked
for (i = 0; i < max_clients; i++)
{
client_socket[i] = 0;
}
// Creating socket file descriptor
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
// Forcefully attaching socket to the port 8080
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR,(char *)&opt, sizeof(opt)) < 0)
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );
// Bind the server to the port and address
if (bind(server_fd, (struct sockaddr *)&address,sizeof(address))<0)
{
perror("Binding Error : ");
exit(EXIT_FAILURE);
}
//listen to the connections
if (listen(server_fd, 5) < 0)
{
perror("Listen Error : ");
exit(EXIT_FAILURE);
}
while(1)
{
//clear the socket set
FD_ZERO(&readfds);
//add master socket to set
FD_SET(server_fd, &readfds);
max_sd = server_fd;
//add child sockets to set
for ( i = 0 ; i < max_clients ; i++)
{
//socket descriptor
sd = client_socket[i];
//if valid socket descriptor then add to read list
if(sd > 0)
FD_SET( sd , &readfds);
//highest file descriptor number, need it for the select function
if(sd > max_sd)
max_sd = sd;
}
//wait for an activity on one of the sockets , timeout is NULL, so wait indefinitely
activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);
if ((activity < 0) && (errno!=EINTR)) printf("select error");
//If something happened on the master socket ,then its an incoming connection
if (FD_ISSET(server_fd, &readfds))
{
if ((new_socket = accept(server_fd, (struct sockaddr *)&address,(socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
//Print out the details of the new connection
printf("New connection , socket fd is %d , ip is : %s , port : %d\n" , new_socket , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
//add new socket to array of sockets
for (i = 0; i < max_clients; i++)
{
//if position is empty
if( client_socket[i] == 0 )
{
client_socket[i] = new_socket;
break;
}
}
}
//else its some IO operation on some other socket
else
{
for (i = 0; i < max_clients; i++)
{
sd = client_socket[i];
if (FD_ISSET( sd , &readfds))
{
//Read the incoming message. If valread = 0, then that client disconnected
valread = read( sd , buffer, 1024) ;
if(valread == 0)
{
//Somebody disconnected , get his details and print
getpeername(sd , (struct sockaddr*)&address ,(socklen_t*)&addrlen);
printf("Host disconnected , ip %s , port %d \n" ,inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
//Increase the closed connection by 1
closed_connections++;
client_socket[i] = 0;
}
//Send message to the client that sent the message
else
{
buffer[valread] = '\0';
getpeername(sd , (struct sockaddr*)&address ,(socklen_t*)&addrlen);
printf("Message received from client connected to port %d is %s \n",ntohs(address.sin_port), buffer );
send(sd , hello , strlen(hello) , 0 );
printf("Hello message sent to client connected on port %d\n", ntohs(address.sin_port));
}
}
}
}
//If all the clients disconnected then break out of while loop
if(closed_connections == max_clients) break;
}
close(server_fd);
return 0;
}
Компиляция client.c
gcc client.c -o client
Компиляция server.c
mpicc server.c -o server
Когда я запускаю сервер и клиент с помощью команды . / client и mpirun -np 2 ./client, я получаю следующий вывод на стороне сервера
New connection , socket fd is 4 , ip is : 127.0.0.1 , port : 57448
New connection , socket fd is 5 , ip is : 127.0.0.1 , port : 57450
Message received from client connected to port 57450 is Hello from client
Hello message sent to client connected on port 57450
Message received from client connected to port 57450 is Hello from client
Hello message sent to client connected on port 57450
Host disconnected , ip 127.0.0.1 , port 57448
Host disconnected , ip 127.0.0.1 , port 57450
Вывод на стороне клиента это:
Hello message sent from client_rank 0
Hello message sent from client_rank 1
The message received from server by client_rank 0 is Hello from server
The message received from server by client_rank 1 is Hello from server
Я не знаю, почему серверу плевать на старого клиента.
Вторая проблема, которую я также заметил, заключается в том, что сервер не получает сообщение2, отправленное клиентом, даже если я использовал функцию select ().Я думаю, что поскольку я использовал функцию выбора, сервер должен отслеживать любые запросы на отправку или отключение, отправленные клиентом.
Любая помощь будет признательна.