lookup.c

This a good VPN source

/*
 * DNS KEY lookup helper
 * Copyright (C) 2002 Michael Richardson <[e-mail]>
 * 
 * This program 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
 * 
 * This program 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.
 */

char lookup_c_version[] = "@(#) RCSID $Id: lookup.c,v 1.8 2004/12/02 06:16:19 mcr Exp $";


#include <stdio.h>
#include <string.h>
#include <stdlib.h> 
#include <unistd.h> 

#include <errno.h>
#include <getopt.h>
#include <setjmp.h>
#include <ctype.h>
#include <signal.h>
#include <time.h>

#include <isc/mem.h>
#include <isc/buffer.h>
#include <dns/rdata.h>
#include <dns/rdatastruct.h>
#include <dns/name.h>
#include <lwres/netdb.h>
#include <lwres/async.h>
#include "lwdnsq.h"

static int lwresd_has_spoken = 0;

char *xstrdup(const char *s)
{
	char *n;

	n = strdup(s);
	if(n == NULL) {
		abort();
	}
	return n;
}

static void free_dl(dnskey_glob *gs, dnskey_lookup *dl)
{
	dnskey_lookup **walk;

	walk = &gs->dns_outstanding;
	while(*walk!=NULL && *walk != dl)
	{
		walk = &((*walk)->next);
	}
	if(*walk != NULL)
	{
		/* if we exit with it non-null, then we
		 * found a matching location, remove
		 * it.
		 */
		*walk = dl->next;
		dl->next = NULL;
	}
	gs->dns_inflight--;

	if(dl->tracking_id) {
		free(dl->tracking_id);
		dl->tracking_id = NULL;
	}
	if(dl->wantedtype_name) {
		free(dl->wantedtype_name);
		dl->wantedtype_name = NULL;
	}
	if(dl->fqdn) {
		free(dl->fqdn);
		dl->fqdn = NULL;
	}
#if 0
	if(dl->last_cname_used) {
		dns_name_free(&dl->last_cname, gs->iscmem);
	}
#endif
	
	free(dl);
}

void lookup_thing(dnskey_glob *gs,
		  dns_rdatatype_t wantedtype,
		  const char *wantedtype_name,
		  char *id,
		  char *fqdn)
{
	isc_mem_t    *iscmem;
	isc_buffer_t *iscbuf;
	int success;
	dnskey_lookup *dl;
	extern void lwres_sanitize_list(lwres_context_t *ctx);

	iscmem=NULL;
	iscbuf=NULL;
	dl = malloc(sizeof(*dl));
	memset(dl, 0, sizeof(*dl));

	dl->tracking_id = strdup(id);
	dl->step = dkl_start;

	output_transaction_line(gs, id, 0, "START", NULL);

	success = lwres_getrrsetbyname_init(fqdn, dns_rdataclass_in,
					    wantedtype, 0 /*flags*/,
					    gs->lwctx, &dl->las);

	if(success != ERRSET_SUCCESS) {
		/* screwed: */
		output_transaction_line(gs, id, 0, "FATAL", "isc buffer error");
		return;
	}

	lwres_sanitize_list(gs->lwctx);

	lwres_getrrsetbyname_xmit(gs->lwctx, &dl->las);

	lwres_sanitize_list(gs->lwctx);

	dl->step = dkl_first;
	dl->wantedtype = wantedtype;
	dl->wantedtype_name = xstrdup(wantedtype_name);
	dl->fqdn = xstrdup(fqdn);
	dl->tracking_id = xstrdup(id);
	time(&dl->resend_time);
	dl->resend_time += LWDNSQ_RETRANSMIT_INTERVAL;
	dl->retry_count = LWDNSQ_RETRANSMIT_INTERVAL;

	/* link it in */
	dl->next = gs->dns_outstanding;
	gs->dns_outstanding = dl;
	
	gs->dns_inflight++;

	return;
}


static int setup_follow_possible_cname(dnskey_glob   *gs,
				       dnskey_lookup *dl)
{
	int ret;

	dl->cname_count++;

	/*
	 * If we are on an odd cycle (starting with 1),
	 * then convert to dns_name_t so that we can compare later.
	 *
	 * This detects loops in the CNAME processing, while still
	 * allowing an arbitrary number of CNAMEs to be followed. 
	 */
	if(dl->cname_count & 1) 
	{
		isc_buffer_t fqdn_src;
		isc_buffer_t *fqdn_dst;

		if(dl->cname_count == 1)
		{
			memset(&dl->last_cname, 0, sizeof(dl->last_cname));
			dns_name_init(&dl->last_cname, NULL);
		}
		else
		{
			dns_name_reset(&dl->last_cname);
		}

		fqdn_dst=NULL;

		isc_buffer_init(&fqdn_src, dl->fqdn, strlen(dl->fqdn));
		isc_buffer_add(&fqdn_src, strlen(dl->fqdn));

		isc_buffer_allocate(gs->iscmem, &fqdn_dst, strlen(dl->fqdn)+1);

#if 0
		if(dl->last_cname_used) {
			dns_name_free(&dl->last_cname, gs->iscmem);
		}
#endif
		dl->last_cname_used = 1;
		if(dns_name_fromtext(&dl->last_cname,
				     &fqdn_src,
				     NULL,
				     1,
				     fqdn_dst) != ISC_R_SUCCESS) {
			return 0;
		}

		/* something else here ? */
	}
				 
	ret = lwres_getrrsetbyname_init(dl->fqdn, dns_rdataclass_in,
					dns_rdatatype_cname, 0 /*flags*/,
					gs->lwctx,
					&dl->las);

	if(ret != ERRSET_SUCCESS) {
		return 0;
	}

	lwres_getrrsetbyname_xmit(gs->lwctx, &dl->las);

	return 1;
}


/*
 * we asked for, and got a CNAME of some kind.
 */
static void process_step_cname(dnskey_glob *gs,
			       dnskey_lookup *dl,
			       struct rrsetinfo *ans,
			       int success)
{
	struct rdatainfo *ri;
	isc_region_t  region;
	dns_rdata_t   rd;
	dns_rdata_cname_t cn;
	char simplebuf[80];
	isc_buffer_t *cname_text;
	char cname_buf[DNS_NAME_MAXTEXT];
	/* char cname_buf2[DNS_NAME_MAXTEXT]; */

	switch(success) {
	case ERRSET_NONAME:
	case ERRSET_NODATA:
		/* no, no CNAME found, thing isn't there */
		snprintf(simplebuf, sizeof(simplebuf),
			 "RR of type %s for %s was not found (tried CNAMEs)",
			 dl->wantedtype_name,
			 dl->fqdn);
		output_transaction_line(gs, dl->tracking_id, 0, "RETRY", 
					simplebuf);
		dl->step = dkl_done;
		return;
		
	case 0:
		/* aha! found a CNAME */
		break;

	default:
	fatal:
		/* some other error */
		snprintf(simplebuf, sizeof(simplebuf), "err=%d", success);
		output_transaction_line(gs, dl->tracking_id, 0, "FATAL", simplebuf);
		dl->step = dkl_done;
		return;
	}

	/*
	 * now process out the CNAMEs, and look them up, one by one...
	 * there should be only one... We just use the first one that works.
	 */

	if(ans->rri_flags & RRSET_VALIDATED) {
		output_transaction_line(gs, dl->tracking_id, 0, "DNSSEC", "OKAY");
	} else {
		output_transaction_line(gs, dl->tracking_id, 0, "DNSSEC", "not present");
	}

	if(ans->rri_nrdatas != 1) {
		/* we got a number of CNAMEs different from 1! */
		success=0;
		snprintf(simplebuf, sizeof(simplebuf), "illegal number of CNAMES: %d", ans->rri_nrdatas);
		output_transaction_line(gs, dl->tracking_id, 0, "FATAL", simplebuf);
		dl->step = dkl_done;
		return;
	}

	/* process first CNAME record */
	ri= &ans->rri_rdatas[0];

	memset(&region, 0, sizeof(region));
	memset(&rd,     0, sizeof(rd));
	
	region.base   =  ri->rdi_data;
	region.length =  ri->rdi_length;

	dns_rdata_fromregion(&rd, dns_rdataclass_in,
			     dns_rdatatype_cname, &region);
	
	/* we set mctx to NULL, which means that the tenure for
	 * the stuff pointed to by cn will persist only as long
	 * as rd persists.
	 */
	if(dns_rdata_tostruct(&rd, &cn, NULL) != ISC_R_SUCCESS) {
		/* failed, try next return error */
		success=0;
		goto fatal;
	}

	cname_text=NULL;
	if(isc_buffer_allocate(gs->iscmem, &cname_text, DNS_NAME_MAXTEXT)) {
		success=0;
		goto fatal;
	}

	if(dns_name_totext(&cn.cname, ISC_TRUE, cname_text) !=
	   ISC_R_SUCCESS) {
		success=0;
		goto fatal;
	}
	
	cname_buf[0]='\0';
	strncat(cname_buf,
		isc_buffer_base(cname_text),
		isc_buffer_usedlength(cname_text));

	/* free up buffer */
	isc_buffer_free(&cname_text);
	
	{
		/* add a trailing . */
		char *end;
		end = &cname_buf[strlen(cname_buf)];
		if(*end != '.') {
			strncat(cname_buf, ".", sizeof(cname_buf));
		}
	}
	
	/* format out a text version */
	output_transaction_line(gs, dl->tracking_id, 0, "CNAME", cname_buf);
	output_transaction_line(gs, dl->tracking_id, 0, "CNAMEFROM", dl->fqdn);
	
	/* check for loops in the CNAMEs! */
	if(dns_name_equal(&dl->last_cname, &cn.cname) == ISC_TRUE) {
		/* damn, we found a loop! */
		dl->step = dkl_done;
		return;
	}

	/* send new request. */