pass_fd.c

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/*
 * $Id: pass_fd.c 4518 2008-07-28 15:39:28Z henningw $
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * Kamailio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History:
 * --------
 *  2002-11-29  created by andrei
 *  2003-02-20  added solaris support (! HAVE_MSGHDR_MSG_CONTROL) (andrei)
 *  2003-11-03  added send_all, recv_all  and updated send/get_fd
 *               to handle signals  (andrei)
 */

#ifdef USE_TCP

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <stdlib.h> /* for NULL definition on openbsd */
#include <errno.h>
#include <string.h>

#include "dprint.h"



/* receive all the data or returns error (handles EINTR etc.)
 * params: socket
 *         data     - buffer for the results
 *         data_len - 
 *         flags    - recv flags for the first recv (see recv(2)), only
 *                    0, MSG_WAITALL and MSG_DONTWAIT make sense
 * if flags is set to MSG_DONWAIT (or to 0 and the socket fd is non-blocking),
 * and if no data is queued on the fd, recv_all will not wait (it will 
 * return error and set errno to EAGAIN/EWOULDBLOCK). However if even 1 byte
 *  is queued, the call will block until the whole data_len was read or an
 *  error or eof occured ("semi-nonblocking" behaviour,  some tcp code
 *   counts on it).
 * if flags is set to MSG_WAITALL it will block even if no byte is available.
 *  
 * returns: bytes read or error (<0)
 * can return < data_len if EOF */
int recv_all(int socket, void* data, int data_len, int flags)
{
   int b_read;
   int n;
   
   b_read=0;
again:
   n=recv(socket, (char*)data, data_len, flags);
   if (n<0){
      /* error */
      if (errno==EINTR) goto again; /* signal, try again */
      /* on EAGAIN just return (let the caller know) */
      if ((errno==EAGAIN)||(errno==EWOULDBLOCK)) return n;
         LM_CRIT("1st recv on %d failed: %s\n", socket, strerror(errno));
         return n;
   }
   b_read+=n;
   while( (b_read!=data_len) && (n)){
      n=recv(socket, (char*)data+b_read, data_len-b_read, MSG_WAITALL);
      if (n<0){
         /* error */
         if (errno==EINTR) continue; /* signal, try again */
         LM_CRIT("2nd recv on %d failed: %s\n",
               socket, strerror(errno));
         return n;
      }
      b_read+=n;
   }
   return b_read;
}



/* sends all data (takes care of signals) (assumes blocking fd)
 * returns number of bytes sent or < 0 for an error */
int send_all(int socket, void* data, int data_len)
{
   int n;
   
again:
   n=send(socket, data, data_len, 0);
   if (n<0){
         /* error */
      if (errno==EINTR) goto again; /* signal, try again */
      LM_CRIT("send on %d failed: %s\n", socket, strerror(errno));
   }
   return n;
}


/* at least 1 byte must be sent! */
int send_fd(int unix_socket, void* data, int data_len, int fd)
{
   struct msghdr msg;
   struct iovec iov[1];
   int ret;
#ifdef HAVE_MSGHDR_MSG_CONTROL
   struct cmsghdr* cmsg;
   /* make sure msg_control will point to properly aligned data */
   union {
      struct cmsghdr cm;
      char control[CMSG_SPACE(sizeof(fd))];
   }control_un;
   
   msg.msg_control=control_un.control;
   /* openbsd doesn't like "more space", msg_controllen must not
    * include the end padding */
   msg.msg_controllen=CMSG_LEN(sizeof(fd));
   
   cmsg=CMSG_FIRSTHDR(&msg);
   cmsg->cmsg_level = SOL_SOCKET;
   cmsg->cmsg_type = SCM_RIGHTS;
   cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
   *(int*)CMSG_DATA(cmsg)=fd;
   msg.msg_flags=0;
#else
   msg.msg_accrights=(caddr_t) &fd;
   msg.msg_accrightslen=sizeof(fd);
#endif
   
   msg.msg_name=0;
   msg.msg_namelen=0;
   
   iov[0].iov_base=data;
   iov[0].iov_len=data_len;
   msg.msg_iov=iov;
   msg.msg_iovlen=1;
   
again:
   ret=sendmsg(unix_socket, &msg, 0);
   if (ret<0){
      if (errno==EINTR) goto again;
      LM_CRIT("sendmsg failed on %d: %s\n", unix_socket, strerror(errno));
   }
   
   return ret;
}



/* receives a fd and data_len data
 * params: unix_socket 
 *         data
 *         data_len
 *         fd         - will be set to the passed fd value or -1 if no fd
 *                      was passed
 *         flags      - 0, MSG_DONTWAIT, MSG_WAITALL; same as recv_all flags
 * returns: bytes read on success, -1 on error (and sets errno) */
int receive_fd(int unix_socket, void* data, int data_len, int* fd, int flags)
{
   struct msghdr msg;
   struct iovec iov[1];
   int new_fd;
   int ret;
   int n;
#ifdef HAVE_MSGHDR_MSG_CONTROL
   struct cmsghdr* cmsg;
   union{
      struct cmsghdr cm;
      char control[CMSG_SPACE(sizeof(new_fd))];
   }control_un;
   
   msg.msg_control=control_un.control;
   msg.msg_controllen=sizeof(control_un.control);
#else
   msg.msg_accrights=(caddr_t) &new_fd;
   msg.msg_accrightslen=sizeof(int);
#endif
   
   msg.msg_name=0;
   msg.msg_namelen=0;
   
   iov[0].iov_base=data;
   iov[0].iov_len=data_len;
   msg.msg_iov=iov;
   msg.msg_iovlen=1;
   
again:
   ret=recvmsg(unix_socket, &msg, flags);
   if (ret<0){
      if (errno==EINTR) goto again;
      if ((errno==EAGAIN)||(errno==EWOULDBLOCK)) goto error;
      LM_CRIT("recvmsg on %d failed: %s\n", unix_socket, strerror(errno));
      goto error;
   }
   if (ret==0){
      /* EOF */
      LM_CRIT("EOF on %d\n", unix_socket);
      goto error;
   }
   if (ret<data_len){
      LM_WARN("too few bytes read (%d from %d) trying to fix...\n", 
            ret, data_len);
      /* blocking recv_all */
      n=recv_all(unix_socket, (char*)data+ret, data_len-ret, MSG_WAITALL);
      if (n>=0) ret+=n;
      else{
         ret=n;
         goto error;
      }
   }
   
#ifdef HAVE_MSGHDR_MSG_CONTROL
   cmsg=CMSG_FIRSTHDR(&msg);
   if ((cmsg!=0) && (cmsg->cmsg_len==CMSG_LEN(sizeof(new_fd)))){
      if (cmsg->cmsg_type!= SCM_RIGHTS){
         LM_ERR("msg control type != SCM_RIGHTS\n");
         ret=-1;
         goto error;
      }
      if (cmsg->cmsg_level!= SOL_SOCKET){
         LM_ERR("msg level != SOL_SOCKET\n");
         ret=-1;
         goto error;
      }
      *fd=*((int*) CMSG_DATA(cmsg));
   }else{
      /*
      LM_ERR("no descriptor passed, cmsg=%p,len=%d\n", 
         cmsg, (unsigned)cmsg->cmsg_len); */
      *fd=-1;
      /* it's not really an error */
   }
#else
   if (msg.msg_accrightslen==sizeof(int)){
      *fd=new_fd;
   }else{
      /*LM_ERR("no descriptor passed, accrightslen=%d\n", 
         msg.msg_accrightslen); */
      *fd=-1;
   }
#endif
   
error:
   return ret;
}
#endif

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