/src/bind9/lib/dns/request.c

Source
/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

/*! \file */

#include <inttypes.h>
#include <stdbool.h>

#include <isc/async.h>
#include <isc/log.h>
#include <isc/loop.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/netmgr.h>
#include <isc/result.h>
#include <isc/thread.h>
#include <isc/tls.h>
#include <isc/util.h>

#include <dns/acl.h>
#include <dns/compress.h>
#include <dns/dispatch.h>
#include <dns/message.h>
#include <dns/rdata.h>
#include <dns/rdatastruct.h>
#include <dns/request.h>
#include <dns/transport.h>
#include <dns/tsig.h>

#define REQUESTMGR_MAGIC      ISC_MAGIC('R', 'q', 'u', 'M')
#define VALID_REQUESTMGR(mgr) ISC_MAGIC_VALID(mgr, REQUESTMGR_MAGIC)

#define REQUEST_MAGIC        ISC_MAGIC('R', 'q', 'u', '!')
#define VALID_REQUEST(request) ISC_MAGIC_VALID(request, REQUEST_MAGIC)

typedef ISC_LIST(dns_request_t) dns_requestlist_t;

struct dns_requestmgr {
  unsigned int magic;
  isc_mem_t *mctx;
  isc_refcount_t references;

  atomic_bool shuttingdown;

  dns_dispatchmgr_t *dispatchmgr;
  dns_dispatchset_t *dispatches4;
  dns_dispatchset_t *dispatches6;
  dns_requestlist_t *requests;
};

struct dns_request {
  unsigned int magic;
  isc_refcount_t references;

  isc_mem_t *mctx;
  int32_t flags;

  isc_loop_t *loop;
  isc_tid_t tid;

  isc_result_t result;
  isc_job_cb cb;
  void *arg;
  ISC_LINK(dns_request_t) link;
  isc_buffer_t *query;
  isc_buffer_t *answer;
  dns_dispatch_t *dispatch;
  dns_dispentry_t *dispentry;
  dns_requestmgr_t *requestmgr;
  isc_buffer_t *tsig;
  dns_tsigkey_t *tsigkey;
  isc_sockaddr_t destaddr;
  unsigned int connect_timeout;
  unsigned int timeout;
  unsigned int udpcount;
};

#define DNS_REQUEST_F_CONNECTING (1 << 0)
#define DNS_REQUEST_F_SENDING  (1 << 1)
#define DNS_REQUEST_F_COMPLETE   (1 << 2)
#define DNS_REQUEST_F_TCP  (1 << 3)

#define DNS_REQUEST_CONNECTING(r) (((r)->flags & DNS_REQUEST_F_CONNECTING) != 0)
#define DNS_REQUEST_SENDING(r)    (((r)->flags & DNS_REQUEST_F_SENDING) != 0)
#define DNS_REQUEST_COMPLETE(r)   (((r)->flags & DNS_REQUEST_F_COMPLETE) != 0)

/***
 *** Forward
 ***/

static isc_result_t
req_render(dns_message_t *message, isc_buffer_t **buffer, unsigned int options,
     isc_mem_t *mctx);
static void
req_response(isc_result_t result, isc_region_t *region, void *arg);
static void
req_senddone(isc_result_t eresult, isc_region_t *region, void *arg);
static void
req_cleanup(dns_request_t *request);
static void
req_sendevent(dns_request_t *request, isc_result_t result);
static void
req_connected(isc_result_t eresult, isc_region_t *region, void *arg);
static void
req_destroy(dns_request_t *request);
static void
req_log(int level, const char *fmt, ...) ISC_FORMAT_PRINTF(2, 3);

/***
 *** Public
 ***/

isc_result_t
dns_requestmgr_create(isc_mem_t *mctx, dns_dispatchmgr_t *dispatchmgr,
          dns_dispatch_t *dispatchv4, dns_dispatch_t *dispatchv6,
          dns_requestmgr_t **requestmgrp) {
  REQUIRE(requestmgrp != NULL && *requestmgrp == NULL);
  REQUIRE(dispatchmgr != NULL);

  req_log(ISC_LOG_DEBUG(3), "%s", __func__);

  dns_requestmgr_t *requestmgr = isc_mem_get(mctx, sizeof(*requestmgr));
  *requestmgr = (dns_requestmgr_t){
    .magic = REQUESTMGR_MAGIC,
  };
  isc_mem_attach(mctx, &requestmgr->mctx);

  uint32_t nloops = isc_loopmgr_nloops();
  requestmgr->requests = isc_mem_cget(requestmgr->mctx, nloops,
              sizeof(requestmgr->requests[0]));
  for (size_t i = 0; i < nloops; i++) {
    ISC_LIST_INIT(requestmgr->requests[i]);

    /* unreferenced in requests_cancel() */
    isc_loop_ref(isc_loop_get(i));
  }

  dns_dispatchmgr_attach(dispatchmgr, &requestmgr->dispatchmgr);

  if (dispatchv4 != NULL) {
    dns_dispatchset_create(requestmgr->mctx, dispatchv4,
               &requestmgr->dispatches4,
               isc_loopmgr_nloops());
  }
  if (dispatchv6 != NULL) {
    dns_dispatchset_create(requestmgr->mctx, dispatchv6,
               &requestmgr->dispatches6,
               isc_loopmgr_nloops());
  }

  isc_refcount_init(&requestmgr->references, 1);

  req_log(ISC_LOG_DEBUG(3), "%s: %p", __func__, requestmgr);

  *requestmgrp = requestmgr;
  return ISC_R_SUCCESS;
}

static void
requests_cancel(void *arg) {
  dns_requestmgr_t *requestmgr = arg;
  isc_tid_t tid = isc_tid();

  ISC_LIST_FOREACH(requestmgr->requests[tid], request, link) {
    req_log(ISC_LOG_DEBUG(3), "%s(%" PRItid ": request %p",
      __func__, tid, request);
    if (DNS_REQUEST_COMPLETE(request)) {
      /* The callback has been already scheduled */
      continue;
    }
    req_sendevent(request, ISC_R_CANCELED);
  }

  isc_loop_unref(isc_loop_get(tid));
  dns_requestmgr_detach(&requestmgr);
}

void
dns_requestmgr_shutdown(dns_requestmgr_t *requestmgr) {
  bool first;
  REQUIRE(VALID_REQUESTMGR(requestmgr));

  req_log(ISC_LOG_DEBUG(3), "%s: %p", __func__, requestmgr);

  rcu_read_lock();
  first = atomic_compare_exchange_strong(&requestmgr->shuttingdown,
                 &(bool){ false }, true);
  rcu_read_unlock();

  if (!first) {
    return;
  }

  /*
   * Wait until all dns_request_create{raw}() are finished, so
   * there will be no new requests added to the lists.
   */
  synchronize_rcu();

  isc_tid_t tid = isc_tid();
  uint32_t nloops = isc_loopmgr_nloops();
  for (size_t i = 0; i < nloops; i++) {
    dns_requestmgr_ref(requestmgr);

    if (i == (uint32_t)tid) {
      /* Run the current loop synchronously */
      requests_cancel(requestmgr);
      continue;
    }

    isc_loop_t *loop = isc_loop_get(i);
    isc_async_run(loop, requests_cancel, requestmgr);
  }
}

static void
requestmgr_destroy(dns_requestmgr_t *requestmgr) {
  req_log(ISC_LOG_DEBUG(3), "%s", __func__);

  INSIST(atomic_load(&requestmgr->shuttingdown));

  size_t nloops = isc_loopmgr_nloops();
  for (size_t i = 0; i < nloops; i++) {
    INSIST(ISC_LIST_EMPTY(requestmgr->requests[i]));
  }
  isc_mem_cput(requestmgr->mctx, requestmgr->requests, nloops,
         sizeof(requestmgr->requests[0]));

  if (requestmgr->dispatches4 != NULL) {
    dns_dispatchset_destroy(&requestmgr->dispatches4);
  }
  if (requestmgr->dispatches6 != NULL) {
    dns_dispatchset_destroy(&requestmgr->dispatches6);
  }
  if (requestmgr->dispatchmgr != NULL) {
    dns_dispatchmgr_detach(&requestmgr->dispatchmgr);
  }
  requestmgr->magic = 0;
  isc_mem_putanddetach(&requestmgr->mctx, requestmgr,
           sizeof(*requestmgr));
}

#if DNS_REQUEST_TRACE
ISC_REFCOUNT_TRACE_IMPL(dns_requestmgr, requestmgr_destroy);
#else
ISC_REFCOUNT_IMPL(dns_requestmgr, requestmgr_destroy);
#endif

static void
req_send(dns_request_t *request) {
  isc_region_t r;

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);

  REQUIRE(VALID_REQUEST(request));

  isc_buffer_usedregion(request->query, &r);

  request->flags |= DNS_REQUEST_F_SENDING;

  /* detached in req_senddone() */
  dns_request_ref(request);
  dns_dispatch_send(request->dispentry, &r);
}

static dns_request_t *
new_request(isc_mem_t *mctx, isc_loop_t *loop, isc_job_cb cb, void *arg,
      bool tcp, unsigned int connect_timeout, unsigned int timeout,
      unsigned int udptimeout, unsigned int udpretries) {
  dns_request_t *request = isc_mem_get(mctx, sizeof(*request));
  *request = (dns_request_t){
    .magic = REQUEST_MAGIC,
    .loop = loop,
    .tid = isc_tid(),
    .cb = cb,
    .arg = arg,
    .link = ISC_LINK_INITIALIZER,
    .result = ISC_R_FAILURE,
    .udpcount = udpretries + 1,
  };

  isc_refcount_init(&request->references, 1);
  isc_mem_attach(mctx, &request->mctx);

  if (tcp) {
    request->connect_timeout = connect_timeout * 1000;
    request->timeout = timeout * 1000;
  } else {
    if (udptimeout == 0) {
      udptimeout = timeout / request->udpcount;
    }
    if (udptimeout == 0) {
      udptimeout = 1;
    }
    request->timeout = udptimeout * 1000;
  }

  return request;
}

static bool
isblackholed(dns_dispatchmgr_t *dispatchmgr, const isc_sockaddr_t *destaddr) {
  dns_acl_t *blackhole;
  isc_netaddr_t netaddr;
  char netaddrstr[ISC_NETADDR_FORMATSIZE];
  int match;
  isc_result_t result;

  blackhole = dns_dispatchmgr_getblackhole(dispatchmgr);
  if (blackhole == NULL) {
    return false;
  }

  isc_netaddr_fromsockaddr(&netaddr, destaddr);
  result = dns_acl_match(&netaddr, NULL, blackhole, NULL, &match, NULL);
  if (result != ISC_R_SUCCESS || match <= 0) {
    return false;
  }

  isc_netaddr_format(&netaddr, netaddrstr, sizeof(netaddrstr));
  req_log(ISC_LOG_DEBUG(10), "blackholed address %s", netaddrstr);

  return true;
}

static isc_result_t
tcp_dispatch(bool newtcp, dns_requestmgr_t *requestmgr,
       const isc_sockaddr_t *srcaddr, const isc_sockaddr_t *destaddr,
       dns_transport_t *transport, dns_dispatch_t **dispatchp) {
  isc_result_t result;

  if (!newtcp) {
    result = dns_dispatch_gettcp(requestmgr->dispatchmgr, destaddr,
               srcaddr, transport, dispatchp);
    if (result == ISC_R_SUCCESS) {
      char peer[ISC_SOCKADDR_FORMATSIZE];

      isc_sockaddr_format(destaddr, peer, sizeof(peer));
      req_log(ISC_LOG_DEBUG(1),
        "attached to TCP connection to %s", peer);
      return result;
    }
  }

  result = dns_dispatch_createtcp(requestmgr->dispatchmgr, srcaddr,
          destaddr, transport, 0, dispatchp);
  return result;
}

static isc_result_t
udp_dispatch(dns_requestmgr_t *requestmgr, const isc_sockaddr_t *srcaddr,
       const isc_sockaddr_t *destaddr, dns_dispatch_t **dispatchp) {
  dns_dispatch_t *disp = NULL;

  if (srcaddr == NULL) {
    switch (isc_sockaddr_pf(destaddr)) {
    case PF_INET:
      disp = dns_dispatchset_get(requestmgr->dispatches4);
      break;

    case PF_INET6:
      disp = dns_dispatchset_get(requestmgr->dispatches6);
      break;

    default:
      return ISC_R_NOTIMPLEMENTED;
    }
    if (disp == NULL) {
      return ISC_R_FAMILYNOSUPPORT;
    }
    dns_dispatch_attach(disp, dispatchp);
    return ISC_R_SUCCESS;
  }

  return dns_dispatch_createudp(requestmgr->dispatchmgr, srcaddr,
              dispatchp);
}

static isc_result_t
get_dispatch(bool tcp, bool newtcp, dns_requestmgr_t *requestmgr,
       const isc_sockaddr_t *srcaddr, const isc_sockaddr_t *destaddr,
       dns_transport_t *transport, dns_dispatch_t **dispatchp) {
  isc_result_t result;

  if (tcp) {
    result = tcp_dispatch(newtcp, requestmgr, srcaddr, destaddr,
              transport, dispatchp);
  } else {
    result = udp_dispatch(requestmgr, srcaddr, destaddr, dispatchp);
  }
  return result;
}

isc_result_t
dns_request_createraw(dns_requestmgr_t *requestmgr, isc_buffer_t *msgbuf,
          const isc_sockaddr_t *srcaddr,
          const isc_sockaddr_t *destaddr,
          dns_transport_t *transport,
          isc_tlsctx_cache_t *tlsctx_cache, unsigned int options,
          unsigned int connect_timeout, unsigned int timeout,
          unsigned int udptimeout, unsigned int udpretries,
          isc_loop_t *loop, isc_job_cb cb, void *arg,
          dns_request_t **requestp) {
  dns_request_t *request = NULL;
  isc_result_t result;
  isc_mem_t *mctx = NULL;
  dns_messageid_t id;
  bool tcp = false;
  bool newtcp = false;
  isc_region_t r;
  unsigned int dispopt = 0;

  REQUIRE(VALID_REQUESTMGR(requestmgr));
  REQUIRE(msgbuf != NULL);
  REQUIRE(destaddr != NULL);
  REQUIRE(loop != NULL);
  REQUIRE(cb != NULL);
  REQUIRE(requestp != NULL && *requestp == NULL);
  REQUIRE(connect_timeout > 0 && timeout > 0);
  REQUIRE(udpretries != UINT_MAX);

  if (srcaddr != NULL) {
    REQUIRE(isc_sockaddr_pf(srcaddr) == isc_sockaddr_pf(destaddr));
  }

  mctx = requestmgr->mctx;

  req_log(ISC_LOG_DEBUG(3), "%s", __func__);

  rcu_read_lock();

  if (atomic_load_acquire(&requestmgr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
    goto done;
  }

  if (isblackholed(requestmgr->dispatchmgr, destaddr)) {
    result = DNS_R_BLACKHOLED;
    goto done;
  }

  isc_buffer_usedregion(msgbuf, &r);
  if (r.length < DNS_MESSAGE_HEADERLEN || r.length > 65535) {
    result = DNS_R_FORMERR;
    goto done;
  }

  if ((options & DNS_REQUESTOPT_TCP) != 0 || r.length > 512) {
    tcp = true;
  }

  request = new_request(mctx, loop, cb, arg, tcp, connect_timeout,
            timeout, udptimeout, udpretries);

  isc_buffer_allocate(mctx, &request->query, r.length + (tcp ? 2 : 0));
  result = isc_buffer_copyregion(request->query, &r);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

again:
  result = get_dispatch(tcp, newtcp, requestmgr, srcaddr, destaddr,
            transport, &request->dispatch);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  if ((options & DNS_REQUESTOPT_FIXEDID) != 0) {
    id = (r.base[0] << 8) | r.base[1];
    dispopt |= DNS_DISPATCHOPT_FIXEDID;
  }

  result = dns_dispatch_add(request->dispatch, loop, dispopt,
          request->connect_timeout, request->timeout,
          destaddr, transport, tlsctx_cache,
          req_connected, req_senddone, req_response,
          request, &id, &request->dispentry);
  if (result != ISC_R_SUCCESS) {
    if ((options & DNS_REQUESTOPT_FIXEDID) != 0 && !newtcp) {
      dns_dispatch_detach(&request->dispatch);
      newtcp = true;
      goto again;
    }

    goto cleanup;
  }

  /* Add message ID. */
  isc_buffer_usedregion(request->query, &r);
  r.base[0] = (id >> 8) & 0xff;
  r.base[1] = id & 0xff;

  request->destaddr = *destaddr;
  request->flags |= DNS_REQUEST_F_CONNECTING;
  if (tcp) {
    request->flags |= DNS_REQUEST_F_TCP;
  }

  dns_requestmgr_attach(requestmgr, &request->requestmgr);
  ISC_LIST_APPEND(requestmgr->requests[request->tid], request, link);

  dns_request_ref(request); /* detached in req_connected() */
  result = dns_dispatch_connect(request->dispentry);
  if (result != ISC_R_SUCCESS) {
    dns_request_unref(request);
    goto cleanup;
  }

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);
  *requestp = request;

cleanup:
  if (result != ISC_R_SUCCESS) {
    req_cleanup(request);
    dns_request_detach(&request);
    req_log(ISC_LOG_DEBUG(3), "%s: failed %s", __func__,
      isc_result_totext(result));
  }

done:
  rcu_read_unlock();
  return result;
}

isc_result_t
dns_request_create(dns_requestmgr_t *requestmgr, dns_message_t *message,
       const isc_sockaddr_t *srcaddr,
       const isc_sockaddr_t *destaddr, dns_transport_t *transport,
       isc_tlsctx_cache_t *tlsctx_cache, unsigned int options,
       dns_tsigkey_t *key, unsigned int connect_timeout,
       unsigned int timeout, unsigned int udptimeout,
       unsigned int udpretries, isc_loop_t *loop, isc_job_cb cb,
       void *arg, dns_request_t **requestp) {
  dns_request_t *request = NULL;
  isc_result_t result;
  isc_mem_t *mctx = NULL;
  dns_messageid_t id;
  bool tcp = false;

  REQUIRE(VALID_REQUESTMGR(requestmgr));
  REQUIRE(message != NULL);
  REQUIRE(destaddr != NULL);
  REQUIRE(loop != NULL);
  REQUIRE(cb != NULL);
  REQUIRE(requestp != NULL && *requestp == NULL);
  REQUIRE(connect_timeout > 0 && timeout > 0);
  REQUIRE(udpretries != UINT_MAX);

  if (srcaddr != NULL &&
      isc_sockaddr_pf(srcaddr) != isc_sockaddr_pf(destaddr))
  {
    return ISC_R_FAMILYMISMATCH;
  }

  mctx = requestmgr->mctx;

  req_log(ISC_LOG_DEBUG(3), "%s", __func__);

  rcu_read_lock();

  if (atomic_load_acquire(&requestmgr->shuttingdown)) {
    result = ISC_R_SHUTTINGDOWN;
    goto done;
  }

  if (isblackholed(requestmgr->dispatchmgr, destaddr)) {
    result = DNS_R_BLACKHOLED;
    goto done;
  }

  if ((options & DNS_REQUESTOPT_TCP) != 0) {
    tcp = true;
  }

  request = new_request(mctx, loop, cb, arg, tcp, connect_timeout,
            timeout, udptimeout, udpretries);

  if (key != NULL) {
    dns_tsigkey_attach(key, &request->tsigkey);
  }

  result = dns_message_settsigkey(message, request->tsigkey);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

again:
  result = get_dispatch(tcp, false, requestmgr, srcaddr, destaddr,
            transport, &request->dispatch);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  result = dns_dispatch_add(request->dispatch, loop, 0,
          request->connect_timeout, request->timeout,
          destaddr, transport, tlsctx_cache,
          req_connected, req_senddone, req_response,
          request, &id, &request->dispentry);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  message->id = id;
  result = req_render(message, &request->query, options, mctx);
  if (result == DNS_R_USETCP && !tcp) {
    /* Try again using TCP. */
    dns_message_renderreset(message);
    dns_dispatch_done(&request->dispentry);
    dns_dispatch_detach(&request->dispatch);
    options |= DNS_REQUESTOPT_TCP;
    tcp = true;
    goto again;
  } else if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  result = dns_message_getquerytsig(message, mctx, &request->tsig);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  request->destaddr = *destaddr;
  request->flags |= DNS_REQUEST_F_CONNECTING;
  if (tcp) {
    request->flags |= DNS_REQUEST_F_TCP;
  }

  dns_requestmgr_attach(requestmgr, &request->requestmgr);
  ISC_LIST_APPEND(requestmgr->requests[request->tid], request, link);

  dns_request_ref(request); /* detached in req_connected() */
  result = dns_dispatch_connect(request->dispentry);
  if (result != ISC_R_SUCCESS) {
    dns_request_unref(request);
    goto cleanup;
  }

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);
  *requestp = request;

cleanup:
  if (result != ISC_R_SUCCESS) {
    req_cleanup(request);
    dns_request_detach(&request);
    req_log(ISC_LOG_DEBUG(3), "%s: failed %s", __func__,
      isc_result_totext(result));
  }
done:
  rcu_read_unlock();

  return result;
}

static isc_result_t
req_render(dns_message_t *message, isc_buffer_t **bufferp, unsigned int options,
     isc_mem_t *mctx) {
  isc_buffer_t *buf1 = NULL;
  isc_buffer_t *buf2 = NULL;
  isc_result_t result;
  isc_region_t r;
  dns_compress_t cctx;
  unsigned int compflags;

  REQUIRE(bufferp != NULL && *bufferp == NULL);

  req_log(ISC_LOG_DEBUG(3), "%s", __func__);

  /*
   * Create buffer able to hold largest possible message.
   */
  isc_buffer_allocate(mctx, &buf1, 65535);

  compflags = 0;
  if ((options & DNS_REQUESTOPT_LARGE) != 0) {
    compflags |= DNS_COMPRESS_LARGE;
  }
  if ((options & DNS_REQUESTOPT_CASE) != 0) {
    compflags |= DNS_COMPRESS_CASE;
  }
  dns_compress_init(&cctx, mctx, compflags);

  /*
   * Render message.
   */
  result = dns_message_renderbegin(message, &cctx, buf1);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }
  result = dns_message_rendersection(message, DNS_SECTION_QUESTION, 0);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }
  result = dns_message_rendersection(message, DNS_SECTION_ANSWER, 0);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }
  result = dns_message_rendersection(message, DNS_SECTION_AUTHORITY, 0);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }
  result = dns_message_rendersection(message, DNS_SECTION_ADDITIONAL, 0);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }
  result = dns_message_renderend(message);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  /*
   * Copy rendered message to exact sized buffer.
   */
  isc_buffer_usedregion(buf1, &r);
  if ((options & DNS_REQUESTOPT_TCP) == 0 && r.length > 512) {
    result = DNS_R_USETCP;
    goto cleanup;
  }
  isc_buffer_allocate(mctx, &buf2, r.length);
  result = isc_buffer_copyregion(buf2, &r);
  if (result != ISC_R_SUCCESS) {
    goto cleanup;
  }

  /*
   * Cleanup and return.
   */
  dns_compress_invalidate(&cctx);
  isc_buffer_free(&buf1);
  *bufferp = buf2;
  return ISC_R_SUCCESS;

cleanup:
  dns_message_renderreset(message);
  dns_compress_invalidate(&cctx);
  if (buf1 != NULL) {
    isc_buffer_free(&buf1);
  }
  if (buf2 != NULL) {
    isc_buffer_free(&buf2);
  }
  return result;
}

static void
request_cancel(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  if (DNS_REQUEST_COMPLETE(request)) {
    /* The request callback was already called */
    return;
  }

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);
  req_sendevent(request, ISC_R_CANCELED); /* call asynchronously */
}

static void
req_cancel_cb(void *arg) {
  dns_request_t *request = arg;

  request_cancel(request);
  dns_request_unref(request);
}

void
dns_request_cancel(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));

  if (request->tid == isc_tid()) {
    request_cancel(request);
  } else {
    dns_request_ref(request);
    isc_async_run(request->loop, req_cancel_cb, request);
  }
}

isc_result_t
dns_request_getresponse(dns_request_t *request, dns_message_t *message,
      unsigned int options) {
  isc_result_t result;

  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());
  REQUIRE(request->answer != NULL);

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);

  dns_message_setquerytsig(message, request->tsig);
  result = dns_message_settsigkey(message, request->tsigkey);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  result = dns_message_parse(message, request->answer, options);
  if (result != ISC_R_SUCCESS) {
    return result;
  }
  if (request->tsigkey != NULL) {
    result = dns_tsig_verify(request->answer, message, NULL, NULL);
  }
  return result;
}

isc_buffer_t *
dns_request_getanswer(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  return request->answer;
}

bool
dns_request_usedtcp(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  return (request->flags & DNS_REQUEST_F_TCP) != 0;
}

void
dns_request_destroy(dns_request_t **requestp) {
  REQUIRE(requestp != NULL && VALID_REQUEST(*requestp));

  dns_request_t *request = *requestp;
  *requestp = NULL;

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);

  if (DNS_REQUEST_COMPLETE(request)) {
    dns_request_cancel(request);
  }

  /* final detach to shut down request */
  dns_request_detach(&request);
}

static void
req_connected(isc_result_t eresult, isc_region_t *region ISC_ATTR_UNUSED,
        void *arg) {
  dns_request_t *request = (dns_request_t *)arg;

  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());
  REQUIRE(DNS_REQUEST_CONNECTING(request));

  req_log(ISC_LOG_DEBUG(3), "%s: request %p: %s", __func__, request,
    isc_result_totext(eresult));

  request->flags &= ~DNS_REQUEST_F_CONNECTING;

  if (DNS_REQUEST_COMPLETE(request)) {
    /* The request callback was already called */
    goto detach;
  }

  if (eresult == ISC_R_SUCCESS) {
    req_send(request);
  } else {
    req_sendevent(request, eresult);
  }

detach:
  /* attached in dns_request_create/_createraw() */
  dns_request_unref(request);
}

static void
req_senddone(isc_result_t eresult, isc_region_t *region ISC_ATTR_UNUSED,
       void *arg) {
  dns_request_t *request = (dns_request_t *)arg;

  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());
  REQUIRE(DNS_REQUEST_SENDING(request));

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);

  request->flags &= ~DNS_REQUEST_F_SENDING;

  if (DNS_REQUEST_COMPLETE(request)) {
    /* The request callback was already called */
    goto detach;
  }

  if (eresult != ISC_R_SUCCESS) {
    req_sendevent(request, eresult);
  }

detach:
  /* attached in req_send() */
  dns_request_unref(request);
}

static void
req_response(isc_result_t eresult, isc_region_t *region, void *arg) {
  dns_request_t *request = (dns_request_t *)arg;

  if (eresult == ISC_R_CANCELED) {
    return;
  }

  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  req_log(ISC_LOG_DEBUG(3), "%s: request %p: %s", __func__, request,
    isc_result_totext(eresult));

  if (DNS_REQUEST_COMPLETE(request)) {
    /* The request callback was already called */
    return;
  }

  switch (eresult) {
  case ISC_R_TIMEDOUT:
    if (request->udpcount > 1 && !dns_request_usedtcp(request)) {
      request->udpcount -= 1;
      dns_dispatch_resume(request->dispentry,
              request->timeout);
      if (!DNS_REQUEST_SENDING(request)) {
        req_send(request);
      }
      return;
    }
    break;
  case ISC_R_SUCCESS:
    /* Copy region to request. */
    isc_buffer_allocate(request->mctx, &request->answer,
            region->length);
    eresult = isc_buffer_copyregion(request->answer, region);
    if (eresult != ISC_R_SUCCESS) {
      isc_buffer_free(&request->answer);
    }
    break;
  default:
    break;
  }

  req_sendevent(request, eresult);
}

static void
req_sendevent_cb(void *arg) {
  dns_request_t *request = arg;

  request->cb(request);
  dns_request_unref(request);
}

static void
req_cleanup(dns_request_t *request) {
  if (ISC_LINK_LINKED(request, link)) {
    ISC_LIST_UNLINK(request->requestmgr->requests[request->tid],
        request, link);
  }
  if (request->dispentry != NULL) {
    dns_dispatch_done(&request->dispentry);
  }
  if (request->dispatch != NULL) {
    dns_dispatch_detach(&request->dispatch);
  }
}

static void
req_sendevent(dns_request_t *request, isc_result_t result) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());
  REQUIRE(!DNS_REQUEST_COMPLETE(request));

  request->flags |= DNS_REQUEST_F_COMPLETE;

  req_cleanup(request);

  req_log(ISC_LOG_DEBUG(3), "%s: request %p: %s", __func__, request,
    isc_result_totext(result));

  request->result = result;

  /*
   * Do not call request->cb directly as it introduces a dead lock
   * between dns_zonemgr_shutdown and sendtoprimary in lib/dns/zone.c
   * zone->lock.
   */
  dns_request_ref(request);
  isc_async_run(request->loop, req_sendevent_cb, request);
}

static void
req_destroy(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());
  REQUIRE(!ISC_LINK_LINKED(request, link));

  req_log(ISC_LOG_DEBUG(3), "%s: request %p", __func__, request);

  /*
   * These should have been cleaned up before the
   * completion event was sent.
   */
  INSIST(!ISC_LINK_LINKED(request, link));
  INSIST(request->dispentry == NULL);
  INSIST(request->dispatch == NULL);

  request->magic = 0;
  if (request->query != NULL) {
    isc_buffer_free(&request->query);
  }
  if (request->answer != NULL) {
    isc_buffer_free(&request->answer);
  }
  if (request->tsig != NULL) {
    isc_buffer_free(&request->tsig);
  }
  if (request->tsigkey != NULL) {
    dns_tsigkey_detach(&request->tsigkey);
  }
  if (request->requestmgr != NULL) {
    dns_requestmgr_detach(&request->requestmgr);
  }
  isc_mem_putanddetach(&request->mctx, request, sizeof(*request));
}

void *
dns_request_getarg(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  return request->arg;
}

isc_result_t
dns_request_getresult(dns_request_t *request) {
  REQUIRE(VALID_REQUEST(request));
  REQUIRE(request->tid == isc_tid());

  return request->result;
}

#if DNS_REQUEST_TRACE
ISC_REFCOUNT_TRACE_IMPL(dns_request, req_destroy);
#else
ISC_REFCOUNT_IMPL(dns_request, req_destroy);
#endif

static void
req_log(int level, const char *fmt, ...) {
  va_list ap;

  va_start(ap, fmt);
  isc_log_vwrite(DNS_LOGCATEGORY_GENERAL, DNS_LOGMODULE_REQUEST, level,
           fmt, ap);
  va_end(ap);
}

Coverage Report

Created: 2025-11-11 07:03