suricata/src/log-dnslog.c

/* Copyright (C) 2007-2013 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

/**
 * \file
 *
 * \author Victor Julien <victor@inliniac.net>
 *
 * Implements dns logging portion of the engine.
 */

#include "suricata-common.h"
#include "debug.h"
#include "detect.h"
#include "pkt-var.h"
#include "conf.h"

#include "threads.h"
#include "threadvars.h"
#include "tm-threads.h"

#include "util-print.h"
#include "util-unittest.h"

#include "util-debug.h"

#include "output.h"
#include "log-dnslog.h"
#include "app-layer-dns-udp.h"
#include "app-layer.h"
#include "util-privs.h"
#include "util-buffer.h"

#include "util-logopenfile.h"
#include "util-time.h"

#define DEFAULT_LOG_FILENAME "dns.log"

#define MODULE_NAME "LogDnsLog"

#define OUTPUT_BUFFER_SIZE 65535

/* we can do query logging as well, but it's disabled for now as the
 * TX id handling doesn't expect it */
#define QUERY 0

typedef struct LogDnsFileCtx_ {
    LogFileCtx *file_ctx;
    uint32_t flags; /** Store mode */
} LogDnsFileCtx;

typedef struct LogDnsLogThread_ {
    LogDnsFileCtx *dnslog_ctx;
    /** LogFileCtx has the pointer to the file and a mutex to allow multithreading */
    uint32_t dns_cnt;

    MemBuffer *buffer;
} LogDnsLogThread;

static void CreateTypeString(uint16_t type, char *str, size_t str_size) {
    if (type == DNS_RECORD_TYPE_A) {
        snprintf(str, str_size, "A");
    } else if (type == DNS_RECORD_TYPE_NS) {
        snprintf(str, str_size, "NS");
    } else if (type == DNS_RECORD_TYPE_AAAA) {
        snprintf(str, str_size, "AAAA");
    } else if (type == DNS_RECORD_TYPE_TXT) {
        snprintf(str, str_size, "TXT");
    } else if (type == DNS_RECORD_TYPE_CNAME) {
        snprintf(str, str_size, "CNAME");
    } else if (type == DNS_RECORD_TYPE_SOA) {
        snprintf(str, str_size, "SOA");
    } else if (type == DNS_RECORD_TYPE_MX) {
        snprintf(str, str_size, "MX");
    } else if (type == DNS_RECORD_TYPE_PTR) {
        snprintf(str, str_size, "PTR");
    } else if (type == DNS_RECORD_TYPE_ANY) {
        snprintf(str, str_size, "ANY");
    } else if (type == DNS_RECORD_TYPE_TKEY) {
        snprintf(str, str_size, "TKEY");
    } else if (type == DNS_RECORD_TYPE_TSIG) {
        snprintf(str, str_size, "TSIG");
    } else {
        snprintf(str, str_size, "%04x/%u", type, type);
    }
}

static void LogQuery(LogDnsLogThread *aft, char *timebuf, char *srcip, char *dstip, Port sp, Port dp, DNSTransaction *tx, DNSQueryEntry *entry) {
    LogDnsFileCtx *hlog = aft->dnslog_ctx;

    SCLogDebug("got a DNS request and now logging !!");

    /* reset */
    MemBufferReset(aft->buffer);

    /* time & tx */
    MemBufferWriteString(aft->buffer,
            "%s [**] Query TX %04x [**] ", timebuf, tx->tx_id);

    /* query */
    PrintRawUriBuf((char *)aft->buffer->buffer, &aft->buffer->offset, aft->buffer->size,
            (uint8_t *)((uint8_t *)entry + sizeof(DNSQueryEntry)),
            entry->len);

    char record[16] = "";
    CreateTypeString(entry->type, record, sizeof(record));
    MemBufferWriteString(aft->buffer,
            " [**] %s [**] %s:%" PRIu16 " -> %s:%" PRIu16 "\n",
            record, srcip, sp, dstip, dp);

    aft->dns_cnt++;

    SCMutexLock(&hlog->file_ctx->fp_mutex);
    (void)MemBufferPrintToFPAsString(aft->buffer, hlog->file_ctx->fp);
    fflush(hlog->file_ctx->fp);
    SCMutexUnlock(&hlog->file_ctx->fp_mutex);
}

static void LogAnswer(LogDnsLogThread *aft, char *timebuf, char *srcip, char *dstip, Port sp, Port dp, DNSTransaction *tx, DNSAnswerEntry *entry) {
    LogDnsFileCtx *hlog = aft->dnslog_ctx;

    SCLogDebug("got a DNS response and now logging !!");

    /* reset */
    MemBufferReset(aft->buffer);

    /* time & tx*/
    MemBufferWriteString(aft->buffer,
            "%s [**] Response TX %04x [**] ", timebuf, tx->tx_id);

    if (entry == NULL) {
        if (tx->no_such_name)
            MemBufferWriteString(aft->buffer, "No Such Name");
        else if (tx->recursion_desired)
            MemBufferWriteString(aft->buffer, "Recursion Desired");
    } else {
        /* query */
        if (entry->fqdn_len > 0) {
            PrintRawUriBuf((char *)aft->buffer->buffer, &aft->buffer->offset, aft->buffer->size,
                    (uint8_t *)((uint8_t *)entry + sizeof(DNSAnswerEntry)),
                    entry->fqdn_len);
        } else {
            MemBufferWriteString(aft->buffer, "<no data>");
        }

        char record[16] = "";
        CreateTypeString(entry->type, record, sizeof(record));
        MemBufferWriteString(aft->buffer,
                " [**] %s [**] TTL %u [**] ", record, entry->ttl);

        uint8_t *ptr = (uint8_t *)((uint8_t *)entry + sizeof(DNSAnswerEntry) + entry->fqdn_len);
        if (entry->type == DNS_RECORD_TYPE_A) {
            char a[16] = "";
            PrintInet(AF_INET, (const void *)ptr, a, sizeof(a));
            MemBufferWriteString(aft->buffer, "%s", a);
        } else if (entry->type == DNS_RECORD_TYPE_AAAA) {
            char a[46];
            PrintInet(AF_INET6, (const void *)ptr, a, sizeof(a));
            MemBufferWriteString(aft->buffer, "%s", a);
        } else if (entry->data_len == 0) {
            MemBufferWriteString(aft->buffer, "<no data>");
        } else {
            PrintRawUriBuf((char *)aft->buffer->buffer, &aft->buffer->offset,
                    aft->buffer->size, ptr, entry->data_len);
        }
    }

    /* ip/tcp header info */
    MemBufferWriteString(aft->buffer,
            " [**] %s:%" PRIu16 " -> %s:%" PRIu16 "\n",
            srcip, sp, dstip, dp);

    aft->dns_cnt++;

    SCMutexLock(&hlog->file_ctx->fp_mutex);
    (void)MemBufferPrintToFPAsString(aft->buffer, hlog->file_ctx->fp);
    fflush(hlog->file_ctx->fp);
    SCMutexUnlock(&hlog->file_ctx->fp_mutex);
}

static TmEcode LogDnsLogIPWrapper(ThreadVars *tv, Packet *p, void *data, PacketQueue *pq,
                            PacketQueue *postpq, int ipproto)
{
    SCEnter();

    LogDnsLogThread *aft = (LogDnsLogThread *)data;
    char timebuf[64];

    /* no flow, no htp state */
    if (p->flow == NULL) {
        SCLogDebug("no flow");
        SCReturnInt(TM_ECODE_OK);
    }

    /* check if we have DNS state or not */
    FLOWLOCK_WRLOCK(p->flow); /* WRITE lock before we updated flow logged id */
    if (FlowGetAppProtocol(p->flow) != ALPROTO_DNS) {
        SCLogDebug("proto not ALPROTO_DNS_UDP: %u", FlowGetAppProtocol(p->flow));
        goto end;
    }

    DNSState *dns_state = (DNSState *)FlowGetAppState(p->flow);
    if (dns_state == NULL) {
        SCLogDebug("no dns state, so no request logging");
        goto end;
    }

    uint64_t total_txs = AppLayerParserGetTxCnt(p->flow->proto, ALPROTO_DNS, dns_state);
    uint64_t tx_id = AppLayerParserGetTransactionLogId(p->flow->alparser);

    SCLogDebug("pcap_cnt %"PRIu64, p->pcap_cnt);
    CreateTimeString(&p->ts, timebuf, sizeof(timebuf));

    char srcip[46], dstip[46];
    Port sp, dp;
    if ((PKT_IS_TOCLIENT(p))) {
        switch (ipproto) {
            case AF_INET:
                PrintInet(AF_INET, (const void *)GET_IPV4_SRC_ADDR_PTR(p), srcip, sizeof(srcip));
                PrintInet(AF_INET, (const void *)GET_IPV4_DST_ADDR_PTR(p), dstip, sizeof(dstip));
                break;
            case AF_INET6:
                PrintInet(AF_INET6, (const void *)GET_IPV6_SRC_ADDR(p), srcip, sizeof(srcip));
                PrintInet(AF_INET6, (const void *)GET_IPV6_DST_ADDR(p), dstip, sizeof(dstip));
                break;
            default:
                goto end;
        }
        sp = p->sp;
        dp = p->dp;
    } else {
        switch (ipproto) {
            case AF_INET:
                PrintInet(AF_INET, (const void *)GET_IPV4_DST_ADDR_PTR(p), srcip, sizeof(srcip));
                PrintInet(AF_INET, (const void *)GET_IPV4_SRC_ADDR_PTR(p), dstip, sizeof(dstip));
                break;
            case AF_INET6:
                PrintInet(AF_INET6, (const void *)GET_IPV6_DST_ADDR(p), srcip, sizeof(srcip));
                PrintInet(AF_INET6, (const void *)GET_IPV6_SRC_ADDR(p), dstip, sizeof(dstip));
                break;
            default:
                goto end;
        }
        sp = p->dp;
        dp = p->sp;
    }
#if QUERY
    if (PKT_IS_TOSERVER(p)) {
        DNSTransaction *tx = NULL;
        TAILQ_FOREACH(tx, &dns_state->tx_list, next) {
            DNSQueryEntry *entry = NULL;
            TAILQ_FOREACH(entry, &tx->query_list, next) {
                LogQuery(aft, timebuf, srcip, dstip, sp, dp, tx, entry);
            }
        }
    } else
#endif

    DNSTransaction *tx = NULL;
    for (; tx_id < total_txs; tx_id++)
    {
        tx = AppLayerParserGetTx(p->flow->proto, ALPROTO_DNS, dns_state, tx_id);
        if (tx == NULL)
            continue;

        /* only consider toserver logging if tx has reply lost set */
        if (PKT_IS_TOSERVER(p) && tx->reply_lost == 0)
            continue;

        DNSQueryEntry *query = NULL;
        TAILQ_FOREACH(query, &tx->query_list, next) {
            LogQuery(aft, timebuf, dstip, srcip, dp, sp, tx, query);
        }

        if (tx->no_such_name)
            LogAnswer(aft, timebuf, srcip, dstip, sp, dp, tx, NULL);
        if (tx->recursion_desired)
            LogAnswer(aft, timebuf, srcip, dstip, sp, dp, tx, NULL);

        DNSAnswerEntry *entry = NULL;
        TAILQ_FOREACH(entry, &tx->answer_list, next) {
            LogAnswer(aft, timebuf, srcip, dstip, sp, dp, tx, entry);
        }

        entry = NULL;
        TAILQ_FOREACH(entry, &tx->authority_list, next) {
            LogAnswer(aft, timebuf, srcip, dstip, sp, dp, tx, entry);
        }

        SCLogDebug("calling AppLayerTransactionUpdateLoggedId");
        AppLayerParserSetTransactionLogId(p->flow->alparser);
    }

end:
    FLOWLOCK_UNLOCK(p->flow);
    SCReturnInt(TM_ECODE_OK);
}

static TmEcode LogDnsLogIPv4(ThreadVars *tv, Packet *p, void *data, PacketQueue *pq, PacketQueue *postpq)
{
    return LogDnsLogIPWrapper(tv, p, data, pq, postpq, AF_INET);
}

static TmEcode LogDnsLogIPv6(ThreadVars *tv, Packet *p, void *data, PacketQueue *pq, PacketQueue *postpq)
{
    return LogDnsLogIPWrapper(tv, p, data, pq, postpq, AF_INET6);
}

TmEcode LogDnsLog (ThreadVars *tv, Packet *p, void *data, PacketQueue *pq, PacketQueue *postpq)
{
    SCEnter();

    SCLogDebug("pcap_cnt %"PRIu64, p->pcap_cnt);
    /* no flow, no htp state */
    if (p->flow == NULL) {
        SCReturnInt(TM_ECODE_OK);
    }

    if (!(PKT_IS_UDP(p)) && !(PKT_IS_TCP(p))) {
        SCReturnInt(TM_ECODE_OK);
    }

    if (PKT_IS_IPV4(p)) {
        int r  = LogDnsLogIPv4(tv, p, data, pq, postpq);
        SCReturnInt(r);
    } else if (PKT_IS_IPV6(p)) {
        int r  = LogDnsLogIPv6(tv, p, data, pq, postpq);
        SCReturnInt(r);
    }

    SCReturnInt(TM_ECODE_OK);
}

static TmEcode LogDnsLogThreadInit(ThreadVars *t, void *initdata, void **data)
{
    LogDnsLogThread *aft = SCMalloc(sizeof(LogDnsLogThread));
    if (unlikely(aft == NULL))
        return TM_ECODE_FAILED;
    memset(aft, 0, sizeof(LogDnsLogThread));

    if(initdata == NULL)
    {
        SCLogDebug("Error getting context for DNSLog.  \"initdata\" argument NULL");
        SCFree(aft);
        return TM_ECODE_FAILED;
    }

    aft->buffer = MemBufferCreateNew(OUTPUT_BUFFER_SIZE);
    if (aft->buffer == NULL) {
        SCFree(aft);
        return TM_ECODE_FAILED;
    }

    /* Use the Ouptut Context (file pointer and mutex) */
    aft->dnslog_ctx= ((OutputCtx *)initdata)->data;

    *data = (void *)aft;
    return TM_ECODE_OK;
}

static TmEcode LogDnsLogThreadDeinit(ThreadVars *t, void *data)
{
    LogDnsLogThread *aft = (LogDnsLogThread *)data;
    if (aft == NULL) {
        return TM_ECODE_OK;
    }

    MemBufferFree(aft->buffer);
    /* clear memory */
    memset(aft, 0, sizeof(LogDnsLogThread));

    SCFree(aft);
    return TM_ECODE_OK;
}

static void LogDnsLogExitPrintStats(ThreadVars *tv, void *data) {
    LogDnsLogThread *aft = (LogDnsLogThread *)data;
    if (aft == NULL) {
        return;
    }

    SCLogInfo("DNS logger logged %" PRIu32 " requests", aft->dns_cnt);
}

static void LogDnsLogDeInitCtx(OutputCtx *output_ctx)
{
    LogDnsFileCtx *dnslog_ctx = (LogDnsFileCtx *)output_ctx->data;
    LogFileFreeCtx(dnslog_ctx->file_ctx);
    SCFree(dnslog_ctx);
    SCFree(output_ctx);
}

/** \brief Create a new dns log LogFileCtx.
 *  \param conf Pointer to ConfNode containing this loggers configuration.
 *  \return NULL if failure, LogFileCtx* to the file_ctx if succesful
 * */
static OutputCtx *LogDnsLogInitCtx(ConfNode *conf)
{
    LogFileCtx* file_ctx = LogFileNewCtx();

    if(file_ctx == NULL) {
        SCLogError(SC_ERR_DNS_LOG_GENERIC, "couldn't create new file_ctx");
        return NULL;
    }

    if (SCConfLogOpenGeneric(conf, file_ctx, DEFAULT_LOG_FILENAME) < 0) {
        LogFileFreeCtx(file_ctx);
        return NULL;
    }

    LogDnsFileCtx *dnslog_ctx = SCMalloc(sizeof(LogDnsFileCtx));
    if (unlikely(dnslog_ctx == NULL)) {
        LogFileFreeCtx(file_ctx);
        return NULL;
    }
    memset(dnslog_ctx, 0x00, sizeof(LogDnsFileCtx));

    dnslog_ctx->file_ctx = file_ctx;

    OutputCtx *output_ctx = SCCalloc(1, sizeof(OutputCtx));
    if (unlikely(output_ctx == NULL)) {
        LogFileFreeCtx(file_ctx);
        SCFree(dnslog_ctx);
        return NULL;
    }

    output_ctx->data = dnslog_ctx;
    output_ctx->DeInit = LogDnsLogDeInitCtx;

    SCLogDebug("DNS log output initialized");

    AppLayerParserRegisterLogger(IPPROTO_UDP, ALPROTO_DNS);
    AppLayerParserRegisterLogger(IPPROTO_TCP, ALPROTO_DNS);

    return output_ctx;
}

void TmModuleLogDnsLogRegister (void) {
    tmm_modules[TMM_LOGDNSLOG].name = MODULE_NAME;
    tmm_modules[TMM_LOGDNSLOG].ThreadInit = LogDnsLogThreadInit;
    tmm_modules[TMM_LOGDNSLOG].Func = LogDnsLog;
    tmm_modules[TMM_LOGDNSLOG].ThreadExitPrintStats = LogDnsLogExitPrintStats;
    tmm_modules[TMM_LOGDNSLOG].ThreadDeinit = LogDnsLogThreadDeinit;
    tmm_modules[TMM_LOGDNSLOG].RegisterTests = NULL;
    tmm_modules[TMM_LOGDNSLOG].cap_flags = 0;

    OutputRegisterModule(MODULE_NAME, "dns-log", LogDnsLogInitCtx);

    /* enable the logger for the app layer */
    SCLogDebug("registered %s", MODULE_NAME);
}