server.old.c

/* 
This code primarily comes from 
http://www.prasannatech.net/2008/07/socket-programming-tutorial.html
and
http://www.binarii.com/files/papers/c_sockets.txt
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#define BUFF_SIZE 1000

char* temperature = "Hello, world";

int start_server(int PORT_NUMBER)
{

      // structs to represent the server and client
      struct sockaddr_in server_addr,client_addr;    
      
      int sock; // socket descriptor

      // 1. socket: creates a socket descriptor that you later use to make other system calls
      if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("Socket");
        exit(1);
      }
      int temp;
      if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&temp,sizeof(int)) == -1) {
        perror("Setsockopt");
        exit(1);
      }

      // configure the server
      server_addr.sin_port = htons(PORT_NUMBER); // specify port number
      server_addr.sin_family = AF_INET;         
      server_addr.sin_addr.s_addr = INADDR_ANY; 
      bzero(&(server_addr.sin_zero),8); 
      
      // 2. bind: use the socket and associate it with the port number
      if (bind(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) {
        perror("Unable to bind");
        exit(1);
      }

      // 3. listen: indicates that we want to listn to the port to which we bound; second arg is number of allowed connections
      if (listen(sock, 5) == -1) {
        perror("Listen");
        exit(1);
      }

      // once you get here, the server is set up and about to start listening
      printf("\nServer configured to listen on port %d\n", PORT_NUMBER);
      fflush(stdout);


      // 4. accept: wait here until we get a connection on that port
      int sin_size = sizeof(struct sockaddr_in);
      int fd = accept(sock, (struct sockaddr *)&client_addr,(socklen_t *)&sin_size);
      printf("Server got a connection from (%s, %d)\n", inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
      
      // buffer to read data into
      char request[1024];
      
      // 5. recv: read incoming message into buffer
      int bytes_received = recv(fd,request,1024,0);
      // null-terminate the string
      request[bytes_received] = '\0';
      printf("Here comes the message:\n");
      printf("%s\n", request);

      // this is the message that we'll send back
      /* it actually looks like this:
        {
           "name": "cit595"
        }
      */
      // char *reply = "{\n\"name\": \"cit595\"\n}\n";
      char reply[BUFF_SIZE] = "{\n\"name\": \"";
      strcat(reply, temperature);
      strcat(reply, "\"\n}\n");
      
      // 6. send: send the message over the socket
      // note that the second argument is a char*, and the third is the number of chars
      send(fd, reply, strlen(reply), 0);
      //printf("Server sent message: %s\n", reply);

      // 7. close: close the socket connection
      close(fd);
      close(sock);
      printf("Server closed connection\n");
  
      return 0;
} 



int main(int argc, char *argv[])
{
  // check the number of arguments
  if (argc != 2)
    {
      printf("\nUsage: server [port_number]\n");
      exit(0);
    }

  int PORT_NUMBER = atoi(argv[1]);
  start_server(PORT_NUMBER);
}