This is the code I am using for a distributed system. The code will be used to allow the server to send parts of a (really big) document which will be processed by the connected clients. Please tell me what things would make it more efficient and if there are any security issues that I can correct without addition of an auth library.#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 lpthreadvoid *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);    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';        puts (client_message);        //Send the message back to client        write(sock , client_message , strlen(client_message));        //clear the message buffer        memset(client_message, 0, 2000);    }    // system (cd; chmod +x script.sh;./script);    if(read_size == 0) {        puts(Client disconnected);        fflush(stdout);    }    else if(read_size == -1) {        perror(recv failed);    }    return 0;}
Server client for distributed system
c;networking;socket
I'm not really into networking, but I can say a little about your coding style:Missing return if (socket_desc == -1) {    printf(Could not create socket);}puts(Socket created);If socket_desc is equal to -1. Could not create socket will be printed as well as Socket created, which is misleading. I think: if (socket_desc == -1) {    printf(Could not create socket);    return -1;                           /* or some other error code */}puts(Socket created);is appropriate and the code doesn't proceeds. OutsourceI'm also not sure if it would be better to outsource this part (as void prepareServer(sockaddr_in *server):server.sin_family = AF_INET;server.sin_addr.s_addr = INADDR_ANY;server.sin_port = htons( 8888 );Unnecessary commentsI don't know who else will read this code but comments like //print the error message followed by this perror(bind failed. Error);will just make the code more obscure, since the goal of the error message is pretty obvious.Calling strlen for no reasonAlso it's not really clear to me, why you need to call strlen(client_message) herewrite(sock , client_message , strlen(client_message));when you store assign read_size a few lines above in the while-condition. strlen will just search for a '\0', which you assign by yourself with read_size...Besides these points I can't see any major mistakes. You should just think about your comments a little more (Do I really need this information? Is this self explaining? Is a single line comment enough here?).As I already said: I can't say much about the networking part, maybe someone else will jump here.