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@oleksiiBobko
Last active July 15, 2024 14:27
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Simple socket server in C using threads (pthread library) Compiles on linux
/*
C socket server example, handles multiple clients using threads
Compile
gcc server.c -lpthread -o server
*/
#include<stdio.h>
#include<string.h> //strlen
#include<stdlib.h> //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h> //write
#include<pthread.h> //for threading , link with lpthread
//the thread function
void *connection_handler(void *);
int main(int argc , char *argv[])
{
int socket_desc , client_sock , c;
struct sockaddr_in server , client;
//Create socket
socket_desc = socket(AF_INET , SOCK_STREAM , 0);
if (socket_desc == -1)
{
printf("Could not create socket");
}
puts("Socket created");
//Prepare the sockaddr_in structure
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons( 8888 );
//Bind
if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)
{
//print the error message
perror("bind failed. Error");
return 1;
}
puts("bind done");
//Listen
listen(socket_desc , 3);
//Accept and incoming connection
puts("Waiting for incoming connections...");
c = sizeof(struct sockaddr_in);
//Accept and incoming connection
puts("Waiting for incoming connections...");
c = sizeof(struct sockaddr_in);
pthread_t thread_id;
while( (client_sock = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)) )
{
puts("Connection accepted");
if( pthread_create( &thread_id , NULL , connection_handler , (void*) &client_sock) < 0)
{
perror("could not create thread");
return 1;
}
//Now join the thread , so that we dont terminate before the thread
//pthread_join( thread_id , NULL);
puts("Handler assigned");
}
if (client_sock < 0)
{
perror("accept failed");
return 1;
}
return 0;
}
/*
* This will handle connection for each client
* */
void *connection_handler(void *socket_desc)
{
//Get the socket descriptor
int sock = *(int*)socket_desc;
int read_size;
char *message , client_message[2000];
//Send some messages to the client
message = "Greetings! I am your connection handler\n";
write(sock , message , strlen(message));
message = "Now type something and i shall repeat what you type \n";
write(sock , message , strlen(message));
//Receive a message from client
while( (read_size = recv(sock , client_message , 2000 , 0)) > 0 )
{
//end of string marker
client_message[read_size] = '\0';
//Send the message back to client
write(sock , client_message , strlen(client_message));
//clear the message buffer
memset(client_message, 0, 2000);
}
if(read_size == 0)
{
puts("Client disconnected");
fflush(stdout);
}
else if(read_size == -1)
{
perror("recv failed");
}
return 0;
}
@praveen-nair
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I see that you have a commented pthread_join (//pthread_join( thread_id , NULL);) So now you are creating 'n' number of threads and not closing the. Why don't you keep an array (thread pool) to save the thread state and clear it as soon as the connection_handler job is completed?

@Nazar2
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Nazar2 commented Jun 21, 2020

Is it true that there is no code to check if thread has finished it's work? What if "client_sock < 0" but there still is some number of unfinished threads?

@halloweeks
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halloweeks commented Feb 22, 2022

@mavstuff
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hi there! This code contains memory leak. See my reporitory for fixed version: https://github.com/mavstuff/threadtest/blob/master/server.c

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