Add adns support in background resolver.

[mLib] / bres-adns.c

/* -*-c-*-
 *
 * $Id: bres-adns.c,v 1.1 2003/12/13 20:37:59 mdw Exp $
 *
 * Background reverse name resolution (ADNS version)
 *
 * (c) 2003 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the mLib utilities library.
 *
 * mLib is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * mLib 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 Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with mLib; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 *
 *
 * HOWEVER, since GNU adns is covered by the full GNU General Public
 * License, this file (only) is also covered by the full GNU GPL, and
 * you may NOT take advantage of the more liberal conditions of the
 * LGPL when modifying or redistributing this file.  This doesn't mean
 * that a program which uses the interface provided by this file is
 * covered by the GPL, since @bres.c@ provides the same interface and
 * is LGPL.  However, it does mean that if your program depends, for
 * some reason (e.g., to meet particular performance criteria), on
 * this adns-based implementation of mLib's background resolver then it
 * must be licensed under the full GPL.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: bres-adns.c,v $
 * Revision 1.1  2003/12/13 20:37:59  mdw
 * Add adns support in background resolver.
 *
 */

#ifndef HAVE_ADNS
#  error "You need the ADNS library to compile this file."
#endif

/*----- Header files ------------------------------------------------------*/

#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <sys/wait.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <adns.h>

#include "alloc.h"
#include "bres.h"
#include "macros.h"
#include "report.h"
#include "sel.h"

/*----- Static variables --------------------------------------------------*/

static adns_state ads;
static sel_state *sel;
static sel_hook selhook;

/*----- Main code ---------------------------------------------------------*/

/* --- @bres_abort@ --- *
 *
 * Arguments:	@bres_client *rc@ = pointer to client block
 *
 * Returns:	---
 *
 * Use:		Removes a queued job.
 */

void bres_abort(bres_client *rc)
{
  if (rc->q == adns_r_addr) xfree(rc->u.name);
  if (rc->a) free(rc->a);
  adns_cancel(rc->aq);
}

/* --- @bres_byaddr@ --- *
 *
 * Arguments:	@bres_client *rc@ = pointer to client block
 *		@struct in_addr addr@ = address to resolve
 *		@void (*func)(struct hostent *h, void *p)@ = handler function
 *		@void *p@ = argument for handler function
 *
 * Returns:	---
 *
 * Use:		Adds an address lookup job to the queue.  The job will be
 *		processed when there's a spare resolver process to deal with
 *		it.
 */

void bres_byaddr(bres_client *rc, struct in_addr addr,
		 void (*func)(struct hostent */*h*/, void */*p*/),
		 void *p)
{
  int e;
  struct sockaddr_in sin;

  if (!ads) goto fail;
  sin.sin_family = AF_INET;
  sin.sin_addr = addr;
  sin.sin_port = 0;
  if ((e = adns_submit_reverse(ads, (struct sockaddr *)&sin, adns_r_ptr,
			       0, rc, &rc->aq)) != 0)
    goto fail;
  rc->a = 0;
  rc->q = adns_r_ptr;
  rc->u.addr = addr;
  rc->func = func;
  rc->p = p;
  return;

fail:
  func(0, p);
}

/* --- @bres_byname@ --- *
 *
 * Arguments:	@bres_client *rc@ = pointer to client block
 *		@const char *name@ = name to resolve
 *		@void (*func)(struct hostent *h, void *p)@ = handler function
 *		@void *p@ = argument for handler function
 *
 * Returns:	---
 *
 * Use:		Adds a name lookup job to the queue.  The job will be
 *		processed when there's a spare resolver process to deal with
 *		it.
 */

void bres_byname(bres_client *rc, const char *name,
		 void (*func)(struct hostent */*h*/, void */*p*/),
		 void *p)
{
  int e;

  if (!ads) goto fail;
  if ((e = adns_submit(ads, name, adns_r_addr,
		       adns_qf_search, rc, &rc->aq)) != 0)
    goto fail;
  rc->a = 0;
  rc->q = adns_r_addr;
  rc->u.name = xstrdup(name);
  rc->func = func;
  rc->p = p;
  return;

fail:
  func(0, p);
}

/* --- @bres_exec@ --- *
 *
 * Arguments:	@const char *file@ = file containing server code or null
 *
 * Returns:	---
 *
 * Use:		Makes `bres' use a standalone server rather than copies of
 *		the current process.  This can reduce memory consumption for
 *		large processes, at the expense of startup time (which
 *		shouldn't be too bad anyway, because of the resolver design).
 *		If the filename is null, a default set up at install time is
 *		used.  It's probably a good idea to leave it alone.
 */

void bres_exec(const char *file)
{
  /* Nothin' doin' */
}

/* --- @report@ --- *
 *
 * Arguments:	@bres_client *c@ = client descriptor block
 *		@adns_answer *a@ = A-record answer from resolver library
 *		@adns_rr_addr *av@ = vector of address records
 *		@int an@ = number of address records (must be positive)
 *		@char **nv@ = vector of name strings
 *		@int nn@ = number of name strings (must be positive)
 *
 * Returns:	---
 *
 * Use:		Formats the given answer into a @struct hostent@ and reports
 *		it to the waiting client application.
 */

static void report(bres_client *rc, adns_answer *a,
		   adns_rr_addr *av, int an,
		   char **nv, int nn)
{
  struct hostent h;
  char *n[16];
  char *aa[16];
  int i, j;

  j = 0;
  if (a->cname) n[j++] = a->cname;
  else { n[j++] = *nv; nv++; nn--; }
  for (i = 0; i < nn && j < N(n) - 1; i++)
    if (strcmp(n[0], nv[i]) != 0) n[j++] = nv[i];
  n[j++] = 0;
  for (i = j = 0; i < an && j < N(av) - 1; i++) {
    if (av[i].addr.sa.sa_family == AF_INET)
      aa[j++] = (char *)&av[i].addr.inet.sin_addr;
  }
  aa[j++] = 0;
  h.h_name = n[0];
  h.h_aliases = n + 1;
  h.h_addrtype = AF_INET;
  h.h_length = sizeof(struct in_addr);
  h.h_addr_list = aa;
  rc->func(&h, rc->p);  
}

/* --- @beforehook@, @afterhook@ --- *
 *
 * Arguments:	@sel_state *s@ = select state
 *		@sel_args *sa@ = argument block
 *		@void *p@ = uninteresting pointer
 *
 * Returns:	---
 *
 * Use:		Processes the selector's arguments before @select@ is
 *		called, to allow ADNS to do its thing.
 */

static void beforehook(sel_state *s, sel_args *sa, void *p)
{
  adns_beforeselect(ads, &sa->maxfd,
		    &sa->fd[SEL_READ], &sa->fd[SEL_WRITE], &sa->fd[SEL_EXC],
		    &sa->tvp, &sa->tv, &sa->now);
}

static void afterhook(sel_state *s, sel_args *sa, void *p)
{
  void *c;
  bres_client *rc;
  adns_query q;
  adns_answer *a;
  int e;
  int i;

  adns_afterselect(ads, sa->maxfd,
		   &sa->fd[SEL_READ], &sa->fd[SEL_WRITE], &sa->fd[SEL_EXC],
		   &sa->now);
  while (q = 0, (e = adns_check(ads, &q, &a, &c)) == 0) {
    rc = c;
    if (a->status != 0)
      goto fail;
    else switch (rc->q) {
      case adns_r_addr:
	assert(a->type == adns_r_addr);
	report(rc, a, a->rrs.addr, a->nrrs, &rc->u.name, 1);
	free(rc->u.name);
	free(a);
	break;
      case adns_r_ptr:
	if (a->type == adns_r_ptr) {
	  rc->a = a;
	  if ((e = adns_submit(ads, a->rrs.str[0], adns_r_addr,
			       0, rc, &q)) != 0)
	    goto fail;
	  rc->aq = q;
	} else {
	  assert(a->type == adns_r_addr);
	  for (i = 0; i < a->nrrs; i++) {
	    if (a->rrs.addr[i].addr.sa.sa_family == AF_INET &&
		a->rrs.addr[i].addr.inet.sin_addr.s_addr ==
		  rc->u.addr.s_addr)
	      goto match;
	  }
	  goto fail;
	match:
	  report(rc, a, &a->rrs.addr[i], 1, rc->a->rrs.str, rc->a->nrrs);
	  free(rc->a);
	  free(a);
	}
	break;
      default:
	abort();
    }
    continue;

  fail:
    rc->func(0, rc->p);
    if (rc->q == adns_r_addr) xfree(rc->u.name);
    if (rc->a) free(rc->a);
    free(a);
  }
}

/* --- @bres_init@ --- *
 *
 * Arguments:	@sel_state *s@ = pointer to select multiplexor
 *
 * Returns:	---
 *
 * Use:		Initializes the background resolver for use.
 */

void bres_init(sel_state *s)
{
  int e;

  if ((e = adns_init(&ads, 0, 0)) != 0) {
    moan("adns_init failed: resolver won't work");
    return;
  }
  sel_addhook(s, &selhook, beforehook, afterhook, 0);
  sel = s;
}

/*----- That's all, folks -------------------------------------------------*/