Thread: UDP Broadcast Client and Server

Hi,
I have determined that my UDP client is sending out more bytes than the server is receiving. For example, if I send "hello" via my client, my server only gets "h". Enclosed is my code. Any thoughts on why it's doing this?

Code:

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

/* Client.c */

int main( int argc, char *argv[])
{
   char buf[512];
   int clientToServer_socket;
   unsigned int fromLength;
   struct sockaddr_in Remote_Address, Server_Address;
   struct hostent *hostPointer;
   int message, checkCall;
   int counter1 = 0;
   int counter2 = 0;
   int broadcastOn = 1;
   int broadcastOff = 0;
   char *broadcastMessage;

   broadcastMessage = "Hello";

   printf("Message %s\n", broadcastMessage); 

   /*Create client socket*/ 
   clientToServer_socket=socket(AF_INET, SOCK_DGRAM, 0);
   if (clientToServer_socket==-1)
	perror("Error: client socket not created");

   /*Fill in client's sockaddr_in */
   bzero(&Remote_Address, sizeof(Remote_Address));
   Remote_Address.sin_family=AF_INET;
   hostPointer=gethostbyname(argv[1]);
   memcpy((unsigned char * ) &Remote_Address.sin_addr, (unsigned char *) hostPointer -> h_addr, hostPointer -> h_length);
   Remote_Address.sin_port=htons(atoi(argv[2]));

   checkCall = setsockopt(clientToServer_socket, SOL_SOCKET, SO_BROADCAST, &broadcastOn, 4);
   if(checkCall == -1)
	perror("Error: setsockopt call failed");
   
   Remote_Address.sin_addr.s_addr|=htonl(0x1ff);

   checkCall = setsockopt(clientToServer_socket, SOL_SOCKET, SO_BROADCAST, &broadcastOff, 4);
   if(checkCall == -1)
	perror("Error: Second setsockopt call failed");

   int broadcastMessageLen = strlen(broadcastMessage) + 1; 
   
   printf("Message test %d\n", broadcastMessageLen);
  
     
   message = sendto(clientToServer_socket, broadcastMessage, broadcastMessageLen, 0, (struct sockaddr *) &Remote_Address, sizeof(Remote_Address));
   if (message ==-1)
	perror("Error: sendto call failed");
   
   while(1)
   {
      fromLength = sizeof(Server_Address);
      message = recvfrom(clientToServer_socket, buf, 512, 0, (struct sockaddr *) &Server_Address, &fromLength);
      if (message ==-1)
	 perror("Error: recvfrom call failed");
  
      printf("SERVER: read %d bytes from IP %s(%s)\n", message, inet_ntoa(Server_Address.sin_addr), buf);
   }
   close(clientToServer_socket);

}

Code:

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

/* Server.c */

int main( int argc, char *argv[])
{
   int server_socket;
   struct sockaddr_in server_address, client_address;
   char buf[512];
   unsigned int clientLength;
   int checkCall, message;
   
   /*Create socket */
   server_socket=socket(AF_INET, SOCK_DGRAM, 0);
   if(server_socket == -1)
        perror("Error: socket failed");

   bzero((char*) &server_address, sizeof(server_address));

   /*Fill in server's sockaddr_in*/
   server_address.sin_family=AF_INET;
   server_address.sin_addr.s_addr=htonl(INADDR_ANY);
   server_address.sin_port=htons(atoi(argv[1]));

   /*Bind server socket and listen for incoming clients*/
   checkCall = bind(server_socket, (struct sockaddr *) &server_address, sizeof(struct sockaddr));
   if(checkCall == -1)
        perror("Error: bind call failed");

   while(1)
   {
	printf("SERVER: waiting for data from client\n");
	
	clientLength = sizeof(client_address);
	message = recvfrom(server_socket, buf, strlen(buf)+1, 0,
		  (struct sockaddr*) &client_address, &clientLength);
	if(message == -1)
        perror("Error: recvfrom call failed");

	printf("SERVER: read %d bytes from IP %s(%s)\n", message,
		  inet_ntoa(client_address.sin_addr), buf);

	if(!strcmp(buf,"quit"))
           break;

	strcpy(buf,"ok");

	message = sendto(server_socket, buf, strlen(buf)+1, 0,
		  (struct sockaddr*) &client_address, sizeof(client_address));
	if(message == -1)
        perror("Error: sendto call failed");		

	printf("SERVER: send completed\n");
   }
   checkCall = close(server_socket);
   if(checkCall == -1)
        perror("Error: bind call failed");

}