func.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <string.h>

#include "func.h"

int PrepareServer(int portno) {


   int sockfd;

   struct sockaddr_in serv_addr;
   
   fprintf(stderr, "Trying to open socket\n");

   /* First call to socket() function */
   sockfd = socket(AF_INET, SOCK_STREAM, 0);
   

   if (sockfd < 0) {
      perror("ERROR opening socket");
      exit(1);
   }

   fprintf(stderr, "Trying to set Socket to SO_REUSEADDR\n");


   if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &(int){ 1 }, sizeof(int)) < 0)
      perror("setsockopt(SO_REUSEADDR) failed");

   /* Initialize socket structure */
   bzero((char *) &serv_addr, sizeof(serv_addr));
   
   serv_addr.sin_family = AF_INET;
   serv_addr.sin_addr.s_addr = INADDR_ANY;
   serv_addr.sin_port = htons(portno);
   
   fprintf(stderr, "Trying to bind\n");

   /* Now bind the host address using bind() call.*/
   if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
      perror("ERROR on binding");
      exit(1);
   }

   return sockfd;

}

void ForkingServer() {
   fprintf(stderr, "Starting ForkingServer\n");
   socklen_t  clilen;
   int sockfd, newsockfd;
   struct sockaddr_in cli_addr;

   char buffer[256];

   sockfd = PrepareServer(5001);


   
   /* Now start listening for the clients, here
      * process will go in sleep mode and will wait
      * for the incoming connection
   */
   
   listen(sockfd,5);
   clilen = sizeof(cli_addr);
   
   while (1) {
      newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
		
      if (newsockfd < 0) {
         perror("ERROR on accept");
         exit(1);
      }
      
      /* Create child process */
      int pid = fork();
		
      if (pid < 0) {
         perror("ERROR on fork");
         exit(1);
      }
      
      if (pid == 0) {
         /* This is the client process */
         close(sockfd);
         doprocessing(newsockfd);
         exit(0);
      }
      else {
         close(newsockfd);
      }
		
   } /* end of while */

}

void MonoServer() {
   fprintf(stderr, "Starting MonoServer\n");

   socklen_t  clilen;
   int sockfd, newsockfd;
   struct sockaddr_in cli_addr;

   char buffer[256];

   sockfd = PrepareServer(5001);

   /* Now start listening for the clients, here process will
      * go in sleep mode and will wait for the incoming connection
   */
   
   listen(sockfd,5);
   clilen = sizeof(cli_addr);
   
   /* Accept actual connection from the client */
   // newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
	
   while (1){

      newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
      //fprintf(stderr,  "got socket %d\n", newsockfd);
      if (newsockfd < 0) {
         perror("ERROR on accept");
         exit(1);
      }
      doprocessing(newsockfd);
      //fprintf(stderr,  "processed socket %d\n", newsockfd);

      close(newsockfd);
      //fprintf(stderr,  "closed socket %d\n", newsockfd);

   }

   fprintf(stderr,  "could not write to socket\n");


   if (newsockfd < 0) {
      perror("ERROR on accept");
      exit(1);
   }
   
}

void doprocessing (int sock) {
   int n;
   char buffer[256];
   bzero(buffer,256);
   n = read(sock,buffer,255);
   
   if (n < 0) {
      perror("ERROR reading from socket");
      exit(1);
   }
   
   fprintf(stderr,  "Here is the message: %s\n",buffer);
   
   if (strcmp(buffer, "deadbeef") == 0){
      fprintf(stderr,  "Message is evil\n");
      n = write(sock,"beef is dead",12);
      __builtin_trap();
   }

   n = write(sock,"I got your message",18);
   
   if (n < 0) {
      fprintf(stderr,  "could not write to socket\n");
      //perror("ERROR writing to socket");
      //exit(1);
   }
	
}