source: code/dns.c

/*
 * 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
}