/*
 * Copyright (c) 2014 Mike Belopuhov
 * Copyright (c) 2014 Eric Faurot <eric@faurot.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <event.h>
#include <resolv.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>

#ifdef __NetBSD__
#define NO_ASYNC
#endif

#ifdef NO_ASYNC
struct asr_result {
	struct addrinfo* ar_addrinfo;
	int ar_gai_errno;
};
#else
#include <asr.h>
#endif

#include "icb.h"
#include "icbd.h"

void dns_done_host(struct asr_result *, void *);
void dns_done_reverse(struct asr_result *, void *);
int  cmp_addr(struct sockaddr *, struct sockaddr *);

extern int dodns;

void
dns_done_host(struct asr_result *ar, void *arg)
{
	struct icb_session *is = arg;
	struct addrinfo *res;
	int found = 0;

	if (ISSETF(is->flags, ICB_SF_PENDINGDROP)) {
		if (ar->ar_addrinfo)
			freeaddrinfo(ar->ar_addrinfo);
		free(is);
		return;
	}

	if (ar->ar_gai_errno == 0) {
		if (strncmp(is->hostname, "localhost",
		    sizeof "localhost" - 1) == 0)
			strlcpy(is->host, "unknown", ICB_MAXHOSTLEN);
		else if (strlen(is->hostname) < ICB_MAXHOSTLEN) {
			for (res = ar->ar_addrinfo; res; res = res->ai_next) {
				if (cmp_addr(res->ai_addr, (struct sockaddr *)
				    &is->ss) == 0) {
					strlcpy(is->host, is->hostname,
					    ICB_MAXHOSTLEN);
					found = 1;
					break;
				}
			}
			if (!found)
				icbd_log(is, LOG_WARNING, "hostname %s does "
				   "not resolve back to connecting ip %s",
				    is->hostname, is->host);
		}
	} else
		icbd_log(is, LOG_DEBUG, "dns resolution failed: %s",
		    gai_strerror(ar->ar_gai_errno));

	if (ar->ar_addrinfo)
		freeaddrinfo(ar->ar_addrinfo);

	CLRF(is->flags, ICB_SF_DNSINPROGRESS);
}

void
dns_done_reverse(struct asr_result *ar, void *arg)
{
	struct icb_session *is = arg;
#ifdef NO_ASYNC
	struct asr_result result;
#else
	struct asr_query *as;
#endif
	struct addrinfo	hints;

	if (ISSETF(is->flags, ICB_SF_PENDINGDROP)) {
		free(is);
		return;
	}

	if (ar->ar_gai_errno == 0) {
		icbd_log(is, LOG_DEBUG, "reverse dns resolved %s to %s",
		    is->host, is->hostname);
		/* try to verify that it resolves back */
		memset(&hints, 0, sizeof(hints));
		hints.ai_family = PF_UNSPEC;
#ifdef NO_ASYNC
		getaddrinfo(is->hostname, NULL, &hints, &result.ar_addrinfo);
		result.ar_gai_errno = errno;
		dns_done_host(&result, is);
#else
		as = getaddrinfo_async(is->hostname, NULL, &hints, NULL);
		event_asr_run(as, dns_done_host, is);
#endif
	} else {
		icbd_log(is, LOG_DEBUG, "reverse dns resolution failed: %s",
		    gai_strerror(ar->ar_gai_errno));
		CLRF(is->flags, ICB_SF_DNSINPROGRESS);
	}
}

int
cmp_addr(struct sockaddr *a, struct sockaddr *b)
{
	if (a->sa_family != b->sa_family)
		return (a->sa_family - b->sa_family);

	if (a->sa_family == AF_INET)
		return (((struct sockaddr_in *)a)->sin_addr.s_addr -
		    ((struct sockaddr_in *)b)->sin_addr.s_addr);

	if (a->sa_family == AF_INET6)
		return (memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
		    &((struct sockaddr_in6 *)b)->sin6_addr,
		    sizeof (struct in6_addr)));

	return -1;
}

void
dns_resolve(struct icb_session *is)
{
#ifdef NO_ASYNC
	struct asr_result result;
#else
	struct asr_query *as;
#endif

	if (!dodns)
		return;

	SETF(is->flags, ICB_SF_DNSINPROGRESS);

	if (verbose)
		icbd_log(is, LOG_DEBUG, "resolving: %s", is->host);

#ifdef NO_ASYNC
	getnameinfo((struct sockaddr *)&is->ss,
		    ((struct sockaddr *)&is->ss)->sa_len, is->hostname,
		    sizeof is->hostname, NULL, 0, NI_NOFQDN);
	result.ar_gai_errno = errno;
	dns_done_reverse(&result, is);
#else
	as = getnameinfo_async((struct sockaddr *)&is->ss,
	    ((struct sockaddr *)&is->ss)->sa_len, is->hostname,
	    sizeof is->hostname, NULL, 0, NI_NOFQDN, NULL);
	event_asr_run(as, dns_done_reverse, is);
#endif
}