Re: [Boost-users] more info-boost install with gentoo issue?

From: Caleb Epstein (caleb.epstein_at_[hidden])
Date: 2004-10-05 14:24:39

On Tue, 5 Oct 2004 12:00:37 -0000 (UTC), dave_at_[hidden]
<dave_at_[hidden]> wrote:
> OK, awake again and looking into the beolow problem more...
> my program pulls a message off of a UDP datagram socket with
> 
>   int s = socket(AF_INET, SOCK_DGRAM, 0);
>   int iVal;
>   struct sockaddr_in oFromAddr;
>   char msg[1024];
>   int iMsgLen;
>   socklen_t iFromLen;
> 
>   oMyAddr.sin_family = AF_INET;
>   oMyAddr.sin_addr.s_addr = htonl(INADDR_ANY);
>   oMyAddr.sin_port = htons(5060);
>   iVal = bind(s, (struct sockaddr *) &oMyAddr, sizeof (oMyAddr));
> 
>   int iVal = recvfrom(s, (void *)&msg, iMsgLen, 0, (struct sockaddr *)
> &oFromAddr, &iFromLen);

If this is the actual code, iMsgLen is being used uninitialized. 
Also, you're passing the address of msg, which is incorrect.  Here's
working code:

#include <iostream>
#include <cstdlib>
#include <cstdio>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

using namespace std;

int
main ()
{
  int s = socket (AF_INET, SOCK_DGRAM, 0);

  if (s < 0)
      {
      perror ("socket");
      return 1;
      }

  struct sockaddr_in addr = {0};

  addr.sin_family = AF_INET;
  addr.sin_addr.s_addr = htonl(INADDR_ANY);
  addr.sin_port = htons(5060);

  if (bind (s, (struct sockaddr *) &addr, sizeof (addr)) != 0)
      {
      perror ("bind");
      return 1;
      }

  char msg[1024];

  while (1)
      {
      socklen_t addrlen = sizeof (addr);

      int len = recvfrom (s, (void *) msg, sizeof (msg), 0,
                          (struct sockaddr*) &addr, &addrlen);

      if (len <= 0)
          {
          perror ("recvfrom");
          return 1;
          }

      cout.write (msg, len);
      cout.flush ();
      }

  return 0;
}

-- 
Caleb Epstein
caleb.epstein_at_[hidden]