/src/gnutls/lib/buffers.c

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/*
 * Copyright (C) 2000-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>
 *
 */

/*
 * This file holds all the buffering code used in gnutls.
 * The buffering code works as:
 *
 * RECORD LAYER:
 *  1. uses a buffer to hold data (application/handshake),
 *    we got but they were not requested, yet.
 *  (see gnutls_record_buffer_put(), gnutls_record_buffer_get_size() etc.)
 *
 *  2. uses a buffer to hold data that were incomplete (ie the read/write
 *    was interrupted)
 *  (see _gnutls_io_read_buffered(), _gnutls_io_write_buffered() etc.)
 *
 * HANDSHAKE LAYER:
 *  1. Uses buffer to hold the last received handshake message.
 *  (see _gnutls_handshake_hash_buffer_put() etc.)
 *
 */

#include "gnutls_int.h"
#include "errors.h"
#include "num.h"
#include "record.h"
#include "buffers.h"
#include "mbuffers.h"
#include "state.h"
#include "dtls.h"
#include "system.h"
#include "constate.h" /* gnutls_epoch_get */
#include "handshake.h" /* remaining_time() */
#include <errno.h>
#include "system.h"
#include "debug.h"

#ifndef EAGAIN
#define EAGAIN EWOULDBLOCK
#endif

/* this is the maximum number of messages allowed to queue.
 */
#define MAX_QUEUE 32

/* Buffers received packets of type APPLICATION DATA,
 * HANDSHAKE DATA and HEARTBEAT.
 */
void _gnutls_record_buffer_put(gnutls_session_t session, content_type_t type,
             uint64_t seq, mbuffer_st *bufel)
{
  bufel->type = type;
  bufel->record_sequence = seq;

  _mbuffer_enqueue(&session->internals.record_buffer, bufel);
  _gnutls_buffers_log("BUF[REC]: Inserted %d bytes of Data(%d)\n",
          (int)bufel->msg.size, (int)type);

  return;
}

/**
 * gnutls_record_check_pending:
 * @session: is a #gnutls_session_t type.
 *
 * This function checks if there are unread data
 * in the gnutls buffers. If the return value is
 * non-zero the next call to gnutls_record_recv()
 * is guaranteed not to block.
 *
 * Returns: Returns the size of the data or zero.
 **/
size_t gnutls_record_check_pending(gnutls_session_t session)
{
  return _gnutls_record_buffer_get_size(session);
}

/**
 * gnutls_record_check_corked:
 * @session: is a #gnutls_session_t type.
 *
 * This function checks if there pending corked
 * data in the gnutls buffers --see gnutls_record_cork().
 *
 * Returns: Returns the size of the corked data or zero.
 *
 * Since: 3.2.8
 **/
size_t gnutls_record_check_corked(gnutls_session_t session)
{
  return session->internals.record_presend_buffer.length;
}

int _gnutls_record_buffer_get(content_type_t type, gnutls_session_t session,
            uint8_t *data, size_t length, uint8_t seq[8])
{
  gnutls_datum_t msg;
  mbuffer_st *bufel;

  if (length == 0 || data == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  bufel = _mbuffer_head_get_first(&session->internals.record_buffer,
          &msg);
  if (bufel == NULL)
    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  if (type != bufel->type) {
    if (IS_DTLS(session))
      _gnutls_audit_log(
        session,
        "Discarded unexpected %s (%d) packet (expecting: %s (%d))\n",
        _gnutls_packet2str(bufel->type),
        (int)bufel->type, _gnutls_packet2str(type),
        (int)type);
    else
      _gnutls_debug_log(
        "received unexpected packet: %s(%d)\n",
        _gnutls_packet2str(bufel->type),
        (int)bufel->type);

    _mbuffer_head_remove_bytes(&session->internals.record_buffer,
             msg.size);
    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);
  }

  if (msg.size <= length)
    length = msg.size;

  if (seq)
    _gnutls_write_uint64(bufel->record_sequence, seq);

  memcpy(data, msg.data, length);
  _mbuffer_head_remove_bytes(&session->internals.record_buffer, length);

  return length;
}

int _gnutls_record_buffer_get_packet(content_type_t type,
             gnutls_session_t session,
             gnutls_packet_t *packet)
{
  mbuffer_st *bufel;

  bufel = _mbuffer_head_pop_first(&session->internals.record_buffer);
  if (bufel == NULL)
    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  if (type != bufel->type) {
    if (IS_DTLS(session))
      _gnutls_audit_log(
        session,
        "Discarded unexpected %s (%d) packet (expecting: %s)\n",
        _gnutls_packet2str(bufel->type),
        (int)bufel->type, _gnutls_packet2str(type));
    _mbuffer_head_remove_bytes(&session->internals.record_buffer,
             bufel->msg.size);
    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);
  }

  *packet = bufel;

  return bufel->msg.size - bufel->mark;
}

inline static void reset_errno(gnutls_session_t session)
{
  session->internals.errnum = 0;
}

inline static int get_errno(gnutls_session_t session, gnutls_transport_ptr_t fd)
{
  int ret;

  if (session->internals.errnum != 0)
    ret = session->internals.errnum;
  else
    ret = session->internals.errno_func(fd);
  return ret;
}

inline static int errno_to_gerr(int err, unsigned dtls)
{
  switch (err) {
  case EAGAIN:
    return GNUTLS_E_AGAIN;
  case EINTR:
    return GNUTLS_E_INTERRUPTED;
  case EMSGSIZE:
    if (dtls != 0)
      return GNUTLS_E_LARGE_PACKET;
    else
      return GNUTLS_E_PUSH_ERROR;
  case ECONNRESET:
    return GNUTLS_E_PREMATURE_TERMINATION;
  default:
    gnutls_assert();
    return GNUTLS_E_PUSH_ERROR;
  }
}

static ssize_t _gnutls_dgram_read(gnutls_session_t session, mbuffer_st **bufel,
          gnutls_pull_func pull_func, unsigned int *ms)
{
  ssize_t i, ret;
  uint8_t *ptr;
  struct timespec t1, t2;
  size_t max_size, recv_size;
  gnutls_transport_ptr_t fd = session->internals.transport_recv_ptr;
  unsigned int diff;

  max_size = max_record_recv_size(session);
  recv_size = max_size;

  session->internals.direction = 0;

  if (ms && *ms > 0) {
    ret = _gnutls_io_check_recv(session, *ms);
    if (ret < 0)
      return gnutls_assert_val(ret);
    gnutls_gettime(&t1);
  }

  *bufel = _mbuffer_alloc_align16(max_size, get_total_headers(session));
  if (*bufel == NULL)
    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  ptr = (*bufel)->msg.data;

  reset_errno(session);
  i = pull_func(fd, ptr, recv_size);

  if (i < 0) {
    int err = get_errno(session, fd);

    _gnutls_read_log("READ: %d returned from %p, errno=%d\n",
         (int)i, fd, err);

    ret = errno_to_gerr(err, 1);
    goto cleanup;
  } else {
    _gnutls_read_log("READ: Got %d bytes from %p\n", (int)i, fd);
    if (i == 0) {
      /* If we get here, we likely have a stream socket.
       * That assumption may not work on DCCP. */
      gnutls_assert();
      ret = 0;
      goto cleanup;
    }

    _mbuffer_set_udata_size(*bufel, i);
  }

  if (ms && *ms > 0) {
    gnutls_gettime(&t2);
    diff = timespec_sub_ms(&t2, &t1);
    if (diff < *ms)
      *ms -= diff;
    else {
      ret = gnutls_assert_val(GNUTLS_E_TIMEDOUT);
      goto cleanup;
    }
  }

  _gnutls_read_log("READ: read %d bytes from %p\n", (int)i, fd);

  return i;

cleanup:
  _mbuffer_xfree(bufel);
  return ret;
}

static ssize_t _gnutls_stream_read(gnutls_session_t session, mbuffer_st **bufel,
           size_t size, gnutls_pull_func pull_func,
           unsigned int *ms)
{
  size_t left;
  ssize_t i = 0;
  size_t max_size = max_record_recv_size(session);
  uint8_t *ptr;
  gnutls_transport_ptr_t fd = session->internals.transport_recv_ptr;
  int ret;
  struct timespec t1, t2;
  unsigned int diff;

  session->internals.direction = 0;

  *bufel = _mbuffer_alloc_align16(MAX(max_size, size),
          get_total_headers(session));
  if (!*bufel) {
    gnutls_assert();
    return GNUTLS_E_MEMORY_ERROR;
  }
  ptr = (*bufel)->msg.data;

  left = size;
  while (left > 0) {
    if (ms && *ms > 0) {
      ret = _gnutls_io_check_recv(session, *ms);
      if (ret < 0) {
        gnutls_assert();
        goto cleanup;
      }

      gnutls_gettime(&t1);
    }

    reset_errno(session);

    i = pull_func(fd, &ptr[size - left], left);

    if (i < 0) {
      int err = get_errno(session, fd);

      _gnutls_read_log(
        "READ: %d returned from %p, errno=%d gerrno=%d\n",
        (int)i, fd, errno, session->internals.errnum);

      if (err == EAGAIN || err == EINTR) {
        if (size - left > 0) {
          _gnutls_read_log(
            "READ: returning %d bytes from %p\n",
            (int)(size - left), fd);

          goto finish;
        }

        ret = errno_to_gerr(err, 0);
        goto cleanup;
      } else {
        gnutls_assert();
        ret = GNUTLS_E_PULL_ERROR;
        goto cleanup;
      }
    } else {
      _gnutls_read_log("READ: Got %d bytes from %p\n", (int)i,
           fd);

      if (i == 0)
        break; /* EOF */
    }

    left -= i;
    (*bufel)->msg.size += i;

    if (ms && *ms > 0 && *ms != GNUTLS_INDEFINITE_TIMEOUT) {
      gnutls_gettime(&t2);
      diff = timespec_sub_ms(&t2, &t1);
      if (diff < *ms)
        *ms -= diff;
      else {
        ret = gnutls_assert_val(GNUTLS_E_TIMEDOUT);
        goto cleanup;
      }
    }
  }

finish:

  _gnutls_read_log("READ: read %d bytes from %p\n", (int)(size - left),
       fd);

  if (size - left == 0)
    _mbuffer_xfree(bufel);

  return (size - left);

cleanup:
  _mbuffer_xfree(bufel);
  return ret;
}

/* This function is like read. But it does not return -1 on error.
 * It does return gnutls_errno instead.
 *
 * Flags are only used if the default recv() function is being used.
 */
static ssize_t _gnutls_read(gnutls_session_t session, mbuffer_st **bufel,
          size_t size, gnutls_pull_func pull_func,
          unsigned int *ms)
{
  if (IS_DTLS(session))
    /* Size is not passed, since a whole datagram will be read. */
    return _gnutls_dgram_read(session, bufel, pull_func, ms);
  else
    return _gnutls_stream_read(session, bufel, size, pull_func, ms);
}

/* @vec: if non-zero then the vector function will be used to
 *       push the data.
 */
static ssize_t _gnutls_writev_emu(gnutls_session_t session,
          gnutls_transport_ptr_t fd,
          const giovec_t *giovec,
          unsigned int giovec_cnt, unsigned vec)
{
  unsigned int j = 0;
  size_t total = 0;
  ssize_t ret = 0;

  for (j = 0; j < giovec_cnt; j++) {
    if (vec) {
      ret = session->internals.vec_push_func(fd, &giovec[j],
                     1);
    } else {
      size_t sent = 0;
      ssize_t left = giovec[j].iov_len;
      char *p = giovec[j].iov_base;
      do {
        ret = session->internals.push_func(fd, p, left);
        if (ret > 0) {
          sent += ret;
          left -= ret;
          p += ret;
        }
      } while (ret > 0 && left > 0);

      if (sent > 0)
        ret = sent;
    }

    if (ret == -1) {
      gnutls_assert();
      break;
    }

    total += ret;

    if ((size_t)ret != giovec[j].iov_len)
      break;
  }

  if (total > 0)
    return total;

  return ret;
}

/* @total: The sum of the data in giovec
 */
static ssize_t _gnutls_writev(gnutls_session_t session, const giovec_t *giovec,
            unsigned giovec_cnt, unsigned total)
{
  int i;
  bool is_dtls = IS_DTLS(session);
  unsigned no_writev = 0;
  gnutls_transport_ptr_t fd = session->internals.transport_send_ptr;

  reset_errno(session);

  if (session->internals.vec_push_func != NULL) {
    if (is_dtls && giovec_cnt > 1) {
      if (total > session->internals.dtls.mtu) {
        no_writev = 1;
      }
    }

    if (no_writev == 0) {
      i = session->internals.vec_push_func(fd, giovec,
                   giovec_cnt);
    } else {
      i = _gnutls_writev_emu(session, fd, giovec, giovec_cnt,
                 1);
    }
  } else if (session->internals.push_func != NULL) {
    i = _gnutls_writev_emu(session, fd, giovec, giovec_cnt, 0);
  } else
    return gnutls_assert_val(GNUTLS_E_PUSH_ERROR);

  if (i == -1) {
    int err = get_errno(session, fd);
    _gnutls_debug_log("WRITE: %d returned from %p, errno: %d\n", i,
          fd, err);

    return errno_to_gerr(err, is_dtls);
  }
  return i;
}

/*
 * @ms: a pointer to the number of milliseconds to wait for data. Use zero or NULL for indefinite.
 *
 * This function is like recv(with MSG_PEEK). But it does not return -1 on error.
 * It does return gnutls_errno instead.
 * This function reads data from the socket and keeps them in a buffer, of up to
 * max_record_recv_size.
 *
 * This is not a general purpose function. It returns EXACTLY the data requested,
 * which are stored in a local (in the session) buffer.
 *
 * If the @ms parameter is non zero then this function will return before
 * the given amount of milliseconds or return GNUTLS_E_TIMEDOUT.
 *
 */
ssize_t _gnutls_io_read_buffered(gnutls_session_t session, size_t total,
         content_type_t recv_type, unsigned int *ms)
{
  ssize_t ret;
  size_t min;
  mbuffer_st *bufel = NULL;
  size_t recvdata, readsize;

  if (total > max_record_recv_size(session) || total == 0) {
    gnutls_assert();
    return GNUTLS_E_RECORD_OVERFLOW;
  }

  /* calculate the actual size, ie. get the minimum of the
   * buffered data and the requested data.
   */
  min = MIN(session->internals.record_recv_buffer.byte_length, total);
  if (min > 0) {
    /* if we have enough buffered data
     * then just return them.
     */
    if (min == total) {
      return min;
    }
  }

  /* min is over zero. recvdata is the data we must
   * receive in order to return the requested data.
   */
  recvdata = total - min;
  readsize = recvdata;

  /* Check if the previously read data plus the new data to
   * receive are longer than the maximum receive buffer size.
   */
  if ((session->internals.record_recv_buffer.byte_length + recvdata) >
      max_record_recv_size(session)) {
    gnutls_assert(); /* internal error */
    return GNUTLS_E_INVALID_REQUEST;
  }

  /* READ DATA
   */
  if (readsize > 0) {
    ret = _gnutls_read(session, &bufel, readsize,
           session->internals.pull_func, ms);

    /* return immediately if we got an interrupt or eagain
     * error.
     */
    if (ret < 0) {
      return gnutls_assert_val(ret);
    }

    if (ret == 0) /* EOF */
      return gnutls_assert_val(0);

    /* copy fresh data to our buffer.
     */
    _gnutls_read_log(
      "RB: Have %d bytes into buffer. Adding %d bytes.\n",
      (int)session->internals.record_recv_buffer.byte_length,
      (int)ret);
    _gnutls_read_log("RB: Requested %d bytes\n", (int)total);

    _mbuffer_enqueue(&session->internals.record_recv_buffer, bufel);

    if (IS_DTLS(session))
      ret = MIN(total, session->internals.record_recv_buffer
             .byte_length);
    else
      ret = session->internals.record_recv_buffer.byte_length;

    if ((ret > 0) && ((size_t)ret < total)) /* Short Read */
      return gnutls_assert_val(GNUTLS_E_AGAIN);
    else
      return ret;
  } else
    return gnutls_assert_val(0);
}

/* This function is like write. But it does not return -1 on error.
 * It does return gnutls_errno instead.
 *
 * This function takes full responsibility of freeing msg->data.
 *
 * In case of E_AGAIN and E_INTERRUPTED errors, you must call
 * gnutls_write_flush(), until it returns ok (0).
 *
 * We need to push exactly the data in msg->size, since we cannot send
 * less data. In TLS the peer must receive the whole packet in order
 * to decrypt and verify the integrity.
 *
 */
ssize_t _gnutls_io_write_buffered(gnutls_session_t session, mbuffer_st *bufel,
          unsigned int mflag)
{
  mbuffer_head_st *const send_buffer =
    &session->internals.record_send_buffer;

  /* to know where the procedure was interrupted.
   */
  session->internals.direction = 1;

  _mbuffer_enqueue(send_buffer, bufel);

  _gnutls_write_log("WRITE: enqueued %d bytes for %p. Total %d bytes.\n",
        (int)bufel->msg.size,
        session->internals.transport_recv_ptr,
        (int)send_buffer->byte_length);

  if (mflag == MBUFFER_FLUSH)
    return _gnutls_io_write_flush(session);
  else
    return bufel->msg.size;
}

typedef ssize_t (*send_func)(gnutls_session_t, const giovec_t *, int);

/* This function writes the data that are left in the
 * TLS write buffer (ie. because the previous write was
 * interrupted.
 */
ssize_t _gnutls_io_write_flush(gnutls_session_t session)
{
  gnutls_datum_t msg;
  mbuffer_head_st *send_buffer = &session->internals.record_send_buffer;
  int ret;
  ssize_t sent = 0, tosend = 0;
  giovec_t iovec[MAX_QUEUE];
  int i = 0;
  mbuffer_st *cur;

  session->internals.direction = 1;
  _gnutls_write_log("WRITE FLUSH: %d bytes in buffer.\n",
        (int)send_buffer->byte_length);

  for (cur = _mbuffer_head_get_first(send_buffer, &msg); cur != NULL;
       cur = _mbuffer_head_get_next(cur, &msg)) {
    iovec[i].iov_base = msg.data;
    iovec[i++].iov_len = msg.size;
    tosend += msg.size;

    /* we buffer up to MAX_QUEUE messages */
    if (i >= MAX_QUEUE) {
      gnutls_assert();
      return GNUTLS_E_INTERNAL_ERROR;
    }
  }

  if (tosend == 0) {
    gnutls_assert();
    return 0;
  }

  ret = _gnutls_writev(session, iovec, i, tosend);
  if (ret >= 0) {
    _mbuffer_head_remove_bytes(send_buffer, ret);
    _gnutls_write_log("WRITE: wrote %d bytes, %d bytes left.\n",
          ret, (int)send_buffer->byte_length);

    sent += ret;
  } else if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
    _gnutls_write_log("WRITE interrupted: %d bytes left.\n",
          (int)send_buffer->byte_length);
    return ret;
  } else if (ret == GNUTLS_E_LARGE_PACKET) {
    _mbuffer_head_remove_bytes(send_buffer, tosend);
    _gnutls_write_log(
      "WRITE cannot send large packet (%u bytes).\n",
      (unsigned int)tosend);
    return ret;
  } else {
    _gnutls_write_log("WRITE error: code %d, %d bytes left.\n", ret,
          (int)send_buffer->byte_length);

    gnutls_assert();
    return ret;
  }

  if (sent < tosend) {
    return gnutls_assert_val(GNUTLS_E_AGAIN);
  }

  return sent;
}

/* Checks whether there are received data within
 * a timeframe.
 *
 * Returns 0 if data were received, GNUTLS_E_TIMEDOUT
 * on timeout and a negative error code on error.
 */
int _gnutls_io_check_recv(gnutls_session_t session, unsigned int ms)
{
  gnutls_transport_ptr_t fd = session->internals.transport_recv_ptr;
  int ret = 0, err;

  if (NO_TIMEOUT_FUNC_SET(session)) {
    _gnutls_debug_log(
      "The pull function has been replaced but not the pull timeout.\n");
    return gnutls_assert_val(GNUTLS_E_PULL_ERROR);
  }

  reset_errno(session);

  ret = session->internals.pull_timeout_func(fd, ms);
  if (ret == -1) {
    err = get_errno(session, fd);
    _gnutls_read_log(
      "READ_TIMEOUT: %d returned from %p, errno=%d (timeout: %u)\n",
      (int)ret, fd, err, ms);
    return errno_to_gerr(err, IS_DTLS(session));
  }

  if (ret > 0)
    return 0;
  else
    return GNUTLS_E_TIMEDOUT;
}

/* HANDSHAKE buffers part
 */

/* This function writes the data that are left in the
 * Handshake write buffer (ie. because the previous write was
 * interrupted.
 *
 */
ssize_t _gnutls_handshake_io_write_flush(gnutls_session_t session)
{
  mbuffer_head_st *const send_buffer =
    &session->internals.handshake_send_buffer;
  gnutls_datum_t msg;
  int ret;
  uint16_t epoch;
  mbuffer_st *cur;

  _gnutls_write_log("HWRITE FLUSH: %d bytes in buffer.\n",
        (int)send_buffer->byte_length);

  if (IS_DTLS(session))
    return _dtls_transmit(session);

  for (cur = _mbuffer_head_get_first(send_buffer, &msg); cur != NULL;
       cur = _mbuffer_head_get_first(send_buffer, &msg)) {
    epoch = cur->epoch;

    if (session->internals.h_read_func) {
      record_parameters_st *params;

      ret = _gnutls_epoch_get(session, epoch, &params);
      if (ret < 0)
        return gnutls_assert_val(ret);
      ret = session->internals.h_read_func(
        session, params->write.level, cur->htype,
        msg.data, msg.size);
      if (ret < 0)
        return gnutls_assert_val(ret);

      ret = msg.size;
    } else {
      ret = _gnutls_send_int(session, cur->type, cur->htype,
                 epoch, msg.data, msg.size, 0);
    }

    if (ret >= 0) {
      ret = _mbuffer_head_remove_bytes(send_buffer, ret);
      /* for each queued message we send, ensure that
       * we drop the epoch refcount set in _gnutls_handshake_io_cache_int(). */
      if (ret == 1)
        _gnutls_epoch_refcount_dec(session, epoch);

      _gnutls_write_log(
        "HWRITE: wrote %d bytes, %d bytes left.\n", ret,
        (int)send_buffer->byte_length);

    } else {
      _gnutls_write_log(
        "HWRITE error: code %d, %d bytes left.\n", ret,
        (int)send_buffer->byte_length);

      gnutls_assert();
      return ret;
    }
  }

  return _gnutls_io_write_flush(session);
}

/* This is a send function for the gnutls handshake
 * protocol. Just makes sure that all data have been sent.
 *
 */
int _gnutls_handshake_io_cache_int(gnutls_session_t session,
           gnutls_handshake_description_t htype,
           mbuffer_st *bufel)
{
  mbuffer_head_st *send_buffer;

  if (IS_DTLS(session)) {
    bufel->handshake_sequence =
      session->internals.dtls.hsk_write_seq - 1;
  }

  send_buffer = &session->internals.handshake_send_buffer;

  /* ensure that our epoch does not get garbage collected
   * before we send all queued messages with it */
  bufel->epoch = (uint16_t)_gnutls_epoch_refcount_inc(
    session, EPOCH_WRITE_CURRENT);
  bufel->htype = htype;
  if (bufel->htype == GNUTLS_HANDSHAKE_CHANGE_CIPHER_SPEC)
    bufel->type = GNUTLS_CHANGE_CIPHER_SPEC;
  else
    bufel->type = GNUTLS_HANDSHAKE;

  _mbuffer_enqueue(send_buffer, bufel);

  _gnutls_write_log("HWRITE: enqueued [%s] %d. Total %d bytes.\n",
        _gnutls_handshake2str(bufel->htype),
        (int)bufel->msg.size, (int)send_buffer->byte_length);

  return 0;
}

static int handshake_compare(const void *_e1, const void *_e2)
{
  const handshake_buffer_st *e1 = _e1;
  const handshake_buffer_st *e2 = _e2;

  if (e1->sequence <= e2->sequence)
    return 1;
  else
    return -1;
}

#define SSL2_HEADERS 1
static int parse_handshake_header(gnutls_session_t session, mbuffer_st *bufel,
          handshake_buffer_st *hsk)
{
  uint8_t *dataptr = NULL; /* for realloc */
  size_t handshake_header_size = HANDSHAKE_HEADER_SIZE(session),
         data_size, frag_size;

  /* Note: SSL2_HEADERS == 1 */
  if (_mbuffer_get_udata_size(bufel) < handshake_header_size)
    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  dataptr = _mbuffer_get_udata_ptr(bufel);

  /* if reading a client hello of SSLv2 */
#ifdef ENABLE_SSL2
  if (unlikely(!IS_DTLS(session) &&
         bufel->htype == GNUTLS_HANDSHAKE_CLIENT_HELLO_V2)) {
    handshake_header_size =
      SSL2_HEADERS; /* we've already read one byte */

    frag_size =
      _mbuffer_get_udata_size(bufel) -
      handshake_header_size; /* we've read the first byte */

    if (dataptr[0] != GNUTLS_HANDSHAKE_CLIENT_HELLO)
      return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);

    hsk->rtype = hsk->htype = GNUTLS_HANDSHAKE_CLIENT_HELLO_V2;

    hsk->sequence = 0;
    hsk->start_offset = 0;
    hsk->length = frag_size;
  } else
#endif
  { /* TLS or DTLS handshake headers */

    hsk->rtype = hsk->htype = dataptr[0];

    /* we do not use DECR_LEN because we know
     * that the packet has enough data.
     */
    hsk->length = _gnutls_read_uint24(&dataptr[1]);

    if (IS_DTLS(session)) {
      hsk->sequence = _gnutls_read_uint16(&dataptr[4]);
      hsk->start_offset = _gnutls_read_uint24(&dataptr[6]);
      frag_size = _gnutls_read_uint24(&dataptr[9]);
    } else {
      hsk->sequence = 0;
      hsk->start_offset = 0;
      frag_size = MIN((_mbuffer_get_udata_size(bufel) -
           handshake_header_size),
          hsk->length);
    }

    /* TLS1.3: distinguish server hello versus hello retry request.
     * The epitome of slick protocol design. */
    if (hsk->htype == GNUTLS_HANDSHAKE_SERVER_HELLO &&
        hsk->start_offset == 0 && !IS_DTLS(session)) {
      if (_mbuffer_get_udata_size(bufel) >
            handshake_header_size + 2 +
              GNUTLS_RANDOM_SIZE &&
          memcmp(dataptr + handshake_header_size + 2,
           HRR_RANDOM, GNUTLS_RANDOM_SIZE) == 0) {
        hsk->htype =
          GNUTLS_HANDSHAKE_HELLO_RETRY_REQUEST;
      }
    }
  }
  data_size = _mbuffer_get_udata_size(bufel) - handshake_header_size;

  if (frag_size > 0)
    hsk->end_offset = hsk->start_offset + frag_size - 1;
  else
    hsk->end_offset = 0;

  _gnutls_handshake_log(
    "HSK[%p]: %s (%u) was received. Length %d[%d], frag offset %d, frag length: %d, sequence: %d\n",
    session, _gnutls_handshake2str(hsk->htype),
    (unsigned)hsk->htype, (int)hsk->length, (int)data_size,
    hsk->start_offset, (int)frag_size, (int)hsk->sequence);

  hsk->header_size = handshake_header_size;
  memcpy(hsk->header, _mbuffer_get_udata_ptr(bufel),
         handshake_header_size);

  if (hsk->length > 0 &&
      (frag_size > data_size ||
       (frag_size > 0 && hsk->end_offset >= hsk->length))) {
    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
  } else if (hsk->length == 0 && hsk->end_offset != 0 &&
       hsk->start_offset != 0)
    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  return handshake_header_size;
}

static void _gnutls_handshake_buffer_move(handshake_buffer_st *dst,
            handshake_buffer_st *src)
{
  memcpy(dst, src, sizeof(*dst));
  memset(src, 0, sizeof(*src));
  src->htype = -1;
}

/* will merge the given handshake_buffer_st to the handshake_recv_buffer
 * list. The given hsk packet will be released in any case (success or failure).
 * Only used in DTLS.
 */
static int merge_handshake_packet(gnutls_session_t session,
          handshake_buffer_st *hsk)
{
  int exists = 0, i, pos = 0;
  int ret;

  for (i = 0; i < session->internals.handshake_recv_buffer_size; i++) {
    if (session->internals.handshake_recv_buffer[i].htype ==
        hsk->htype) {
      exists = 1;
      pos = i;
      break;
    }
  }

  if (!exists)
    pos = session->internals.handshake_recv_buffer_size;

  if (pos >= MAX_HANDSHAKE_MSGS)
    return gnutls_assert_val(GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETS);

  if (!exists) {
    if (hsk->length != hsk->data.length) {
      ret = _gnutls_buffer_resize(&hsk->data, hsk->length);
      if (ret < 0)
        return gnutls_assert_val(ret);

      hsk->data.length = hsk->length;
    }

    if (hsk->length > 0 && hsk->end_offset > 0 &&
        hsk->end_offset - hsk->start_offset + 1 != hsk->length) {
      memmove(&hsk->data.data[hsk->start_offset],
        hsk->data.data,
        hsk->end_offset - hsk->start_offset + 1);
    }

    session->internals.handshake_recv_buffer_size++;

    /* rewrite headers to make them look as each packet came as a single fragment */
    _gnutls_write_uint24(hsk->length, &hsk->header[1]);
    _gnutls_write_uint24(0, &hsk->header[6]);
    _gnutls_write_uint24(hsk->length, &hsk->header[9]);

    _gnutls_handshake_buffer_move(
      &session->internals.handshake_recv_buffer[pos], hsk);

  } else {
    if (hsk->start_offset <
          session->internals.handshake_recv_buffer[pos]
            .start_offset &&
        hsk->end_offset + 1 >=
          session->internals.handshake_recv_buffer[pos]
            .start_offset) {
      memcpy(&session->internals.handshake_recv_buffer[pos]
          .data.data[hsk->start_offset],
             hsk->data.data, hsk->data.length);
      session->internals.handshake_recv_buffer[pos]
        .start_offset = hsk->start_offset;
      session->internals.handshake_recv_buffer[pos]
        .end_offset = MIN(
        hsk->end_offset,
        session->internals.handshake_recv_buffer[pos]
          .end_offset);
    } else if (hsk->end_offset >
           session->internals.handshake_recv_buffer[pos]
             .end_offset &&
         hsk->start_offset <=
           session->internals.handshake_recv_buffer[pos]
               .end_offset +
             1) {
      memcpy(&session->internals.handshake_recv_buffer[pos]
          .data.data[hsk->start_offset],
             hsk->data.data, hsk->data.length);

      session->internals.handshake_recv_buffer[pos]
        .end_offset = hsk->end_offset;
      session->internals.handshake_recv_buffer[pos]
        .start_offset = MIN(
        hsk->start_offset,
        session->internals.handshake_recv_buffer[pos]
          .start_offset);
    }
    _gnutls_handshake_buffer_clear(hsk);
  }

  return 0;
}

/* returns non-zero on match and zero on mismatch
 */
inline static int cmp_hsk_types(gnutls_handshake_description_t expected,
        gnutls_handshake_description_t recvd)
{
  if (expected == GNUTLS_HANDSHAKE_ANY)
    return 1;

#ifdef ENABLE_SSL2
  if (expected == GNUTLS_HANDSHAKE_CLIENT_HELLO &&
      recvd == GNUTLS_HANDSHAKE_CLIENT_HELLO_V2)
    return 1;
#endif
  if (expected != recvd)
    return 0;

  return 1;
}

#define LAST_ELEMENT (session->internals.handshake_recv_buffer_size - 1)

/* returns the last stored handshake packet.
 */
static int get_last_packet(gnutls_session_t session,
         gnutls_handshake_description_t htype,
         handshake_buffer_st *hsk, unsigned int optional)
{
  handshake_buffer_st *recv_buf =
    session->internals.handshake_recv_buffer;

  if (IS_DTLS(session)) {
    if (session->internals.handshake_recv_buffer_size == 0 ||
        (session->internals.dtls.hsk_read_seq !=
         recv_buf[LAST_ELEMENT].sequence))
      goto timeout;

    if (htype != recv_buf[LAST_ELEMENT].htype) {
      if (optional == 0)
        _gnutls_audit_log(
          session,
          "Received unexpected handshake message '%s' (%d). Expected '%s' (%d)\n",
          _gnutls_handshake2str(
            recv_buf[0].htype),
          (int)recv_buf[0].htype,
          _gnutls_handshake2str(htype),
          (int)htype);

      return gnutls_assert_val(
        GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET);
    }

    else if ((recv_buf[LAST_ELEMENT].start_offset == 0 &&
        recv_buf[LAST_ELEMENT].end_offset ==
          recv_buf[LAST_ELEMENT].length - 1) ||
       recv_buf[LAST_ELEMENT].length == 0) {
      session->internals.dtls.hsk_read_seq++;
      _gnutls_handshake_buffer_move(hsk,
                  &recv_buf[LAST_ELEMENT]);
      session->internals.handshake_recv_buffer_size--;
      return 0;
    } else {
      /* if we don't have a complete handshake message, but we
       * have queued data waiting, try again to reconstruct the
       * handshake packet, using the queued */
      if (recv_buf[LAST_ELEMENT].end_offset !=
            recv_buf[LAST_ELEMENT].length - 1 &&
          record_check_unprocessed(session) > 0)
        return gnutls_assert_val(
          GNUTLS_E_INT_CHECK_AGAIN);
      else
        goto timeout;
    }
  } else { /* TLS */

    if (session->internals.handshake_recv_buffer_size > 0 &&
        recv_buf[0].length == recv_buf[0].data.length) {
      if (cmp_hsk_types(htype, recv_buf[0].htype) == 0) {
        return gnutls_assert_val(
          GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET);
      }

      _gnutls_handshake_buffer_move(hsk, &recv_buf[0]);
      session->internals.handshake_recv_buffer_size--;
      return 0;
    } else
      return gnutls_assert_val(
        GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);
  }

timeout:
  RETURN_DTLS_EAGAIN_OR_TIMEOUT(session, 0);
}

/* This is a receive function for the gnutls handshake
 * protocol. Makes sure that we have received all data.
 *
 * htype is the next handshake packet expected.
 */
int _gnutls_parse_record_buffered_msgs(gnutls_session_t session)
{
  gnutls_datum_t msg;
  mbuffer_st *bufel = NULL, *prev = NULL;
  int ret;
  size_t data_size;
  handshake_buffer_st *recv_buf =
    session->internals.handshake_recv_buffer;

  bufel = _mbuffer_head_get_first(&session->internals.record_buffer,
          &msg);
  if (bufel == NULL)
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;

  if (!IS_DTLS(session)) {
    ssize_t append, header_size;

    do {
      if (bufel->type != GNUTLS_HANDSHAKE)
        return gnutls_assert_val(
          GNUTLS_E_UNEXPECTED_PACKET);

      if (unlikely(
            session->internals
                .handshake_recv_buffer_size ==
              0 &&
            msg.size < HANDSHAKE_HEADER_SIZE(session) &&
            session->internals
                .handshake_header_recv_buffer
                .byte_length <
              HANDSHAKE_HEADER_SIZE(session) -
                msg.size)) {
        bufel = _mbuffer_head_pop_first(
          &session->internals.record_buffer);
        _mbuffer_enqueue(
          &session->internals
             .handshake_header_recv_buffer,
          bufel);
        break;
      } else if (session->internals.handshake_recv_buffer_size >
             0 &&
           recv_buf[0].length >
             recv_buf[0].data.length) {
        /* this is the rest of a previous message */
        append = MIN(msg.size,
               recv_buf[0].length -
                 recv_buf[0].data.length);

        ret = _gnutls_buffer_append_data(
          &recv_buf[0].data, msg.data, append);
        if (ret < 0)
          return gnutls_assert_val(ret);

        _mbuffer_head_remove_bytes(
          &session->internals.record_buffer,
          append);
      } else { /* received new message */
        if (unlikely(
              session->internals
                .handshake_header_recv_buffer
                .length > 0)) {
          bufel = _mbuffer_head_pop_first(
            &session->internals
               .record_buffer);
          _mbuffer_enqueue(
            &session->internals
               .handshake_header_recv_buffer,
            bufel);
          ret = _mbuffer_linearize_align16(
            &session->internals
               .handshake_header_recv_buffer,
            get_total_headers(session));
          if (ret < 0)
            return gnutls_assert_val(ret);
          bufel = _mbuffer_head_pop_first(
            &session->internals
               .handshake_header_recv_buffer);
          _mbuffer_head_push_first(
            &session->internals
               .record_buffer,
            bufel);
        }

        ret = parse_handshake_header(session, bufel,
                   &recv_buf[0]);
        if (ret < 0)
          return gnutls_assert_val(ret);

        header_size = ret;
        session->internals.handshake_recv_buffer_size =
          1;

        _mbuffer_set_uhead_size(bufel, header_size);

        data_size = MIN(recv_buf[0].length,
            _mbuffer_get_udata_size(bufel));
        ret = _gnutls_buffer_append_data(
          &recv_buf[0].data,
          _mbuffer_get_udata_ptr(bufel),
          data_size);
        if (ret < 0)
          return gnutls_assert_val(ret);
        _mbuffer_set_uhead_size(bufel, 0);
        _mbuffer_head_remove_bytes(
          &session->internals.record_buffer,
          data_size + header_size);
      }

      /* if packet is complete then return it
       */
      if (recv_buf[0].length == recv_buf[0].data.length) {
        return 0;
      }
      bufel = _mbuffer_head_get_first(
        &session->internals.record_buffer, &msg);
    } while (bufel != NULL);

    /* if we are here it means that the received packets were not
     * enough to complete the handshake packet.
     */
    return gnutls_assert_val(GNUTLS_E_AGAIN);
  } else { /* DTLS */

    handshake_buffer_st tmp;

    do {
      /* we now
       * 0. parse headers
       * 1. insert to handshake_recv_buffer
       * 2. sort handshake_recv_buffer on sequence numbers
       * 3. return first packet if completed or GNUTLS_E_AGAIN.
       */
      do {
        if (bufel->type != GNUTLS_HANDSHAKE) {
          gnutls_assert();
          goto next; /* ignore packet */
        }

        _gnutls_handshake_buffer_init(&tmp);

        ret = parse_handshake_header(session, bufel,
                   &tmp);
        if (ret < 0) {
          gnutls_assert();
          _gnutls_audit_log(
            session,
            "Invalid handshake packet headers. Discarding.\n");
          break;
        }

        _mbuffer_consume(
          &session->internals.record_buffer,
          bufel, ret);

        data_size = MIN(tmp.length,
            tmp.end_offset -
              tmp.start_offset + 1);

        ret = _gnutls_buffer_append_data(
          &tmp.data,
          _mbuffer_get_udata_ptr(bufel),
          data_size);
        if (ret < 0)
          return gnutls_assert_val(ret);

        _mbuffer_consume(
          &session->internals.record_buffer,
          bufel, data_size);

        ret = merge_handshake_packet(session, &tmp);
        if (ret < 0)
          return gnutls_assert_val(ret);

      } while (_mbuffer_get_udata_size(bufel) > 0);

      prev = bufel;
      bufel = _mbuffer_dequeue(
        &session->internals.record_buffer, bufel);

      _mbuffer_xfree(&prev);
      continue;

    next:
      bufel = _mbuffer_head_get_next(bufel, NULL);
    } while (bufel != NULL);

    /* sort in descending order */
    if (session->internals.handshake_recv_buffer_size > 1)
      qsort(recv_buf,
            session->internals.handshake_recv_buffer_size,
            sizeof(recv_buf[0]), handshake_compare);

    while (session->internals.handshake_recv_buffer_size > 0 &&
           recv_buf[LAST_ELEMENT].sequence <
             session->internals.dtls.hsk_read_seq) {
      _gnutls_audit_log(
        session,
        "Discarded replayed handshake packet with sequence %d\n",
        recv_buf[LAST_ELEMENT].sequence);
      _gnutls_handshake_buffer_clear(&recv_buf[LAST_ELEMENT]);
      session->internals.handshake_recv_buffer_size--;
    }

    return 0;
  }
}

/* This is a receive function for the gnutls handshake
 * protocol. Makes sure that we have received all data.
 */
ssize_t _gnutls_handshake_io_recv_int(gnutls_session_t session,
              gnutls_handshake_description_t htype,
              handshake_buffer_st *hsk,
              unsigned int optional)
{
  int ret;
  unsigned int tleft = 0;
  int retries = 7;

  ret = get_last_packet(session, htype, hsk, optional);
  if (ret != GNUTLS_E_AGAIN && ret != GNUTLS_E_INTERRUPTED &&
      ret != GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE &&
      ret != GNUTLS_E_INT_CHECK_AGAIN) {
    return gnutls_assert_val(ret);
  }

  /* try using the already existing records before
   * trying to receive.
   */
  ret = _gnutls_parse_record_buffered_msgs(session);

  if (ret == 0) {
    ret = get_last_packet(session, htype, hsk, optional);
  }

  if (IS_DTLS(session)) {
    if (ret >= 0)
      return ret;
  } else {
    if ((ret != GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE && ret < 0) ||
        ret >= 0)
      return gnutls_assert_val(ret);
  }

  /* If handshake is handled manually, don't receive records from I/O */
  if (session->internals.h_read_func)
    return GNUTLS_E_AGAIN;

  if (htype != (gnutls_handshake_description_t)-1) {
    ret = handshake_remaining_time(session);
    if (ret < 0)
      return gnutls_assert_val(ret);
    tleft = ret;
  }

  do {
    /* if we don't have a complete message waiting for us, try
     * receiving more */
    ret = _gnutls_recv_in_buffers(session, GNUTLS_HANDSHAKE, htype,
                tleft);
    if (ret < 0)
      return gnutls_assert_val_fatal(ret);

    ret = _gnutls_parse_record_buffered_msgs(session);
    if (ret == 0) {
      ret = get_last_packet(session, htype, hsk, optional);
    }
    /* we put an upper limit (retries) to the number of partial handshake
     * messages in a record packet. */
  } while (IS_DTLS(session) && ret == GNUTLS_E_INT_CHECK_AGAIN &&
     retries-- > 0);

  if (unlikely(IS_DTLS(session) && ret == GNUTLS_E_INT_CHECK_AGAIN)) {
    ret = gnutls_assert_val(GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETS);
  }

  return ret;
}

Coverage Report

Created: 2025-03-06 06:58