/*

 * Copyright (C) 2017 Red Hat, 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/>

 *

 */

#include "gnutls_int.h"

#include "compress.h"

#include "errors.h"

#include "extv.h"

#include "handshake.h"

#include "tls13/certificate.h"

#include "auth/cert.h"

#include "mbuffers.h"

#include "ext/compress_certificate.h"

#include "ext/status_request.h"

static int parse_cert_extension(void *ctx, unsigned tls_id, const uint8_t *data,

        unsigned data_size);

static int parse_cert_list(gnutls_session_t session, uint8_t *data,

         size_t data_size);

static int compress_certificate(gnutls_buffer_st *buf, unsigned cert_pos_mark,

        gnutls_compression_method_t comp_method);

static int decompress_certificate(gnutls_session_t session,

          gnutls_buffer_st *buf);

int _gnutls13_recv_certificate(gnutls_session_t session)

{

  int ret, err, decompress_cert = 0;

  gnutls_buffer_st buf;

  unsigned optional = 0;

  if (!session->internals.initial_negotiation_completed &&

      session->internals.hsk_flags & HSK_PSK_SELECTED)

    return 0;

  if (session->security_parameters.entity == GNUTLS_SERVER) {

    /* if we didn't request a certificate, there will not be any */

    if (session->internals.send_cert_req == 0)

      return 0;

    if (session->internals.send_cert_req != GNUTLS_CERT_REQUIRE)

      optional = 1;

  }

  ret = _gnutls_recv_handshake(session, GNUTLS_HANDSHAKE_CERTIFICATE_PKT,

             0, &buf);

  if (ret == GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET) {

    /* check if we received compressed certificate */

    err = _gnutls_recv_handshake(

      session, GNUTLS_HANDSHAKE_COMPRESSED_CERTIFICATE_PKT, 0,

      &buf);

    if (err >= 0) {

      /* fail if we receive unsolicited compressed certificate */

      if (!(session->internals.hsk_flags &

            HSK_COMP_CRT_REQ_SENT))

        return gnutls_assert_val(

          GNUTLS_E_UNEXPECTED_PACKET);

      decompress_cert = 1;

      ret = err;

    }

  }

  if (ret < 0) {

    if (ret == GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET &&

        session->internals.send_cert_req)

      return gnutls_assert_val(GNUTLS_E_NO_CERTIFICATE_FOUND);

    return gnutls_assert_val(ret);

  }

  if (buf.length == 0) {

    gnutls_assert();

    ret = GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;

    goto cleanup;

  }

  if (decompress_cert) {

    ret = decompress_certificate(session, &buf);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

  }

  if (session->internals.initial_negotiation_completed &&

      session->internals.post_handshake_cr_context.size > 0) {

    gnutls_datum_t context;

    /* verify whether the context matches */

    ret = _gnutls_buffer_pop_datum_prefix8(&buf, &context);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    if (context.size !=

          session->internals.post_handshake_cr_context.size ||

        memcmp(context.data,

         session->internals.post_handshake_cr_context.data,

         context.size) != 0) {

      ret = GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;

      gnutls_assert();

      goto cleanup;

    }

  } else {

    if (buf.data[0] != 0) {

      /* The context field must be empty during handshake */

      gnutls_assert();

      ret = GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;

      goto cleanup;

    }

    /* buf.length is positive */

    buf.data++;

    buf.length--;

  }

  _gnutls_handshake_log("HSK[%p]: parsing certificate message\n",

            session);

  ret = parse_cert_list(session, buf.data, buf.length);

  if (ret < 0) {

    if (ret == GNUTLS_E_NO_CERTIFICATE_FOUND) {

      if (optional)

        ret = 0;

      else if (session->security_parameters.entity ==

         GNUTLS_SERVER)

        ret = GNUTLS_E_CERTIFICATE_REQUIRED;

    }

    gnutls_assert();

    goto cleanup;

  }

  session->internals.hsk_flags |= HSK_CRT_VRFY_EXPECTED;

  ret = 0;

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

struct ocsp_req_ctx_st {

  gnutls_pcert_st *pcert;

  unsigned cert_index;

  gnutls_session_t session;

  gnutls_certificate_credentials_t cred;

};

static int append_status_request(void *_ctx, gnutls_buffer_st *buf)

{

  struct ocsp_req_ctx_st *ctx = _ctx;

  gnutls_session_t session = ctx->session;

  int ret;

  gnutls_datum_t resp;

  unsigned free_resp = 0;

  assert(session->internals.selected_ocsp_func != NULL ||

         session->internals.selected_ocsp_length != 0);

  /* The global ocsp callback function can only be used to return

   * a single certificate request */

  if (session->internals.selected_ocsp_length == 1 &&

      ctx->cert_index != 0)

    return 0;

  if (session->internals.selected_ocsp_length > 0) {

    if (ctx->cert_index < session->internals.selected_ocsp_length) {

      if ((session->internals.selected_ocsp[ctx->cert_index]

               .exptime != 0 &&

           gnutls_time(0) >=

             session->internals

               .selected_ocsp[ctx->cert_index]

               .exptime) ||

          session->internals.selected_ocsp[ctx->cert_index]

              .response.data == NULL) {

        return 0;

      }

      resp.data = session->internals

              .selected_ocsp[ctx->cert_index]

              .response.data;

      resp.size = session->internals

              .selected_ocsp[ctx->cert_index]

              .response.size;

      ret = 0;

    } else {

      return 0;

    }

  } else if (session->internals.selected_ocsp_func) {

    if (ctx->cert_index == 0) {

      ret = session->internals.selected_ocsp_func(

        session,

        session->internals.selected_ocsp_func_ptr,

        &resp);

      free_resp = 1;

    } else {

      return 0;

    }

  } else

    return 0;

  if (ret == GNUTLS_E_NO_CERTIFICATE_STATUS || resp.data == 0) {

    return 0;

  } else if (ret < 0) {

    return gnutls_assert_val(ret);

  }

  ret = _gnutls_buffer_append_data(buf, "\x01", 1);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_buffer_append_data_prefix(buf, 24, resp.data, resp.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = 0;

cleanup:

  if (free_resp)

    gnutls_free(resp.data);

  return ret;

}

int _gnutls13_send_certificate(gnutls_session_t session, unsigned again)

{

  int ret, compress_cert;

  gnutls_pcert_st *apr_cert_list = NULL;

  gnutls_privkey_t apr_pkey = NULL;

  int apr_cert_list_length = 0;

  mbuffer_st *bufel = NULL;

  gnutls_buffer_st buf;

  unsigned pos_mark, ext_pos_mark, cert_pos_mark;

  unsigned i;

  struct ocsp_req_ctx_st ctx;

  gnutls_certificate_credentials_t cred;

  gnutls_compression_method_t comp_method;

  gnutls_handshake_description_t h_type;

  comp_method = gnutls_compress_certificate_get_selected_method(session);

  compress_cert = comp_method != GNUTLS_COMP_UNKNOWN;

  h_type = compress_cert ? GNUTLS_HANDSHAKE_COMPRESSED_CERTIFICATE_PKT :

         GNUTLS_HANDSHAKE_CERTIFICATE_PKT;

  if (again == 0) {

    if (!session->internals.initial_negotiation_completed &&

        session->internals.hsk_flags & HSK_PSK_SELECTED)

      return 0;

    if (session->security_parameters.entity == GNUTLS_SERVER &&

        session->internals.resumed)

      return 0;

    cred = (gnutls_certificate_credentials_t)_gnutls_get_cred(

      session, GNUTLS_CRD_CERTIFICATE);

    if (cred == NULL) {

      gnutls_assert();

      return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

    }

    if (session->security_parameters.entity == GNUTLS_CLIENT &&

        !(session->internals.hsk_flags & HSK_CRT_ASKED)) {

      return 0;

    }

    ret = _gnutls_get_selected_cert(session, &apr_cert_list,

            &apr_cert_list_length,

            &apr_pkey);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    cert_pos_mark = buf.length;

    if (session->security_parameters.entity == GNUTLS_CLIENT) {

      ret = _gnutls_buffer_append_data_prefix(

        &buf, 8,

        session->internals.post_handshake_cr_context

          .data,

        session->internals.post_handshake_cr_context

          .size);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

    } else {

      ret = _gnutls_buffer_append_prefix(&buf, 8, 0);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

    }

    /* mark total size */

    pos_mark = buf.length;

    ret = _gnutls_buffer_append_prefix(&buf, 24, 0);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    for (i = 0; i < (unsigned)apr_cert_list_length; i++) {

      ret = _gnutls_buffer_append_data_prefix(

        &buf, 24, apr_cert_list[i].cert.data,

        apr_cert_list[i].cert.size);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

#ifdef ENABLE_OCSP

      if ((session->internals.selected_ocsp_length > 0 ||

           session->internals.selected_ocsp_func) &&

          (((session->internals.hsk_flags &

             HSK_OCSP_REQUESTED) &&

            IS_SERVER(session)) ||

           ((session->internals.hsk_flags &

             HSK_CLIENT_OCSP_REQUESTED) &&

            !IS_SERVER(session)))) {

        /* append status response if available */

        ret = _gnutls_extv_append_init(&buf);

        if (ret < 0) {

          gnutls_assert();

          goto cleanup;

        }

        ext_pos_mark = ret;

        ctx.pcert = &apr_cert_list[i];

        ctx.cert_index = i;

        ctx.session = session;

        ctx.cred = cred;

        ret = _gnutls_extv_append(

          &buf, STATUS_REQUEST_TLS_ID, &ctx,

          append_status_request);

        if (ret < 0) {

          gnutls_assert();

          goto cleanup;

        }

        ret = _gnutls_extv_append_final(

          &buf, ext_pos_mark, 0);

        if (ret < 0) {

          gnutls_assert();

          goto cleanup;

        }

      } else

#endif

      {

        ret = _gnutls_buffer_append_prefix(&buf, 16, 0);

        if (ret < 0) {

          gnutls_assert();

          goto cleanup;

        }

      }

    }

    _gnutls_write_uint24(buf.length - pos_mark - 3,

             &buf.data[pos_mark]);

    if (compress_cert) {

      ret = compress_certificate(&buf, cert_pos_mark,

               comp_method);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel, h_type);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

typedef struct crt_cert_ctx_st {

  gnutls_session_t session;

  gnutls_datum_t *ocsp;

  unsigned idx;

} crt_cert_ctx_st;

static int parse_cert_extension(void *_ctx, unsigned tls_id,

        const uint8_t *data, unsigned data_size)

{

  crt_cert_ctx_st *ctx = _ctx;

  gnutls_session_t session = ctx->session;

  int ret;

  if (tls_id == STATUS_REQUEST_TLS_ID) {

#ifdef ENABLE_OCSP

    if (!_gnutls_hello_ext_is_present(session,

              ext_mod_status_request.gid)) {

      gnutls_assert();

      goto unexpected;

    }

    _gnutls_handshake_log("Found OCSP response on cert %d\n",

              ctx->idx);

    ret = _gnutls_parse_ocsp_response(session, data, data_size,

              ctx->ocsp);

    if (ret < 0)

      return gnutls_assert_val(ret);

#endif

  } else {

    goto unexpected;

  }

  return 0;

unexpected:

  _gnutls_debug_log("received unexpected certificate extension (%d)\n",

        (int)tls_id);

  return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);

}

static int parse_cert_list(gnutls_session_t session, uint8_t *data,

         size_t data_size)

{

  int ret;

  size_t len;

  uint8_t *p = data;

  cert_auth_info_t info;

  gnutls_certificate_credentials_t cred;

  size_t size;

  int i;

  unsigned npeer_certs, npeer_ocsp, j;

  crt_cert_ctx_st ctx;

  gnutls_datum_t *peer_certs = NULL;

  gnutls_datum_t *peer_ocsp = NULL;

  unsigned nentries = 0;

  cred = (gnutls_certificate_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_CERTIFICATE);

  if (cred == NULL) {

    gnutls_assert();

    return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

  }

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_CERTIFICATE,

            sizeof(cert_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  if (data == NULL || data_size == 0) {

    /* no certificate was sent */

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  }

  info = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);

  if (info == NULL)

    return gnutls_assert_val(GNUTLS_E_INSUFFICIENT_CREDENTIALS);

  DECR_LEN(data_size, 3);

  size = _gnutls_read_uint24(p);

  p += 3;

  if (size != data_size)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (size == 0)

    return gnutls_assert_val(GNUTLS_E_NO_CERTIFICATE_FOUND);

  i = data_size;

  while (i > 0) {

    DECR_LEN(data_size, 3);

    len = _gnutls_read_uint24(p);

    if (len == 0)

      return gnutls_assert_val(

        GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

    DECR_LEN(data_size, len);

    p += len + 3;

    i -= len + 3;

    DECR_LEN(data_size, 2);

    len = _gnutls_read_uint16(p);

    DECR_LEN(data_size, len);

    i -= len + 2;

    p += len + 2;

    nentries++;

  }

  if (data_size != 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  /* this is unnecessary - keeping to avoid a regression due to a re-org

   * of the loop above */

  if (nentries == 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  npeer_ocsp = 0;

  npeer_certs = 0;

  /* Ok we now allocate the memory to hold the

   * certificate list

   */

  peer_certs = gnutls_calloc(nentries, sizeof(gnutls_datum_t));

  if (peer_certs == NULL)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  peer_ocsp = gnutls_calloc(nentries, sizeof(gnutls_datum_t));

  if (peer_ocsp == NULL) {

    ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

    goto cleanup;

  }

  p = data + 3;

  /* Now we start parsing the list (again).

   * We don't use DECR_LEN since the list has

   * been parsed before.

   */

  ctx.session = session;

  for (j = 0; j < nentries; j++) {

    len = _gnutls_read_uint24(p);

    p += 3;

    ret = _gnutls_set_datum(&peer_certs[j], p, len);

    if (ret < 0) {

      gnutls_assert();

      ret = GNUTLS_E_CERTIFICATE_ERROR;

      goto cleanup;

    }

    npeer_certs++;

    p += len;

    len = _gnutls_read_uint16(p);

    ctx.ocsp = &peer_ocsp[j];

    ctx.idx = j;

    ret = _gnutls_extv_parse(&ctx, parse_cert_extension, p,

           len + 2);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    p += len + 2;

    npeer_ocsp++;

  }

  /* The OCSP entries match the certificate entries, although

   * the contents of each OCSP entry may be NULL.

   */

  for (j = 0; j < info->ncerts; j++)

    gnutls_free(info->raw_certificate_list[j].data);

  gnutls_free(info->raw_certificate_list);

  for (j = 0; j < info->nocsp; j++)

    gnutls_free(info->raw_ocsp_list[j].data);

  gnutls_free(info->raw_ocsp_list);

  info->raw_certificate_list = peer_certs;

  info->ncerts = npeer_certs;

  info->raw_ocsp_list = peer_ocsp;

  info->nocsp = npeer_ocsp;

  return 0;

cleanup:

  for (j = 0; j < npeer_certs; j++)

    gnutls_free(peer_certs[j].data);

  for (j = 0; j < npeer_ocsp; j++)

    gnutls_free(peer_ocsp[j].data);

  gnutls_free(peer_certs);

  gnutls_free(peer_ocsp);

  return ret;

}

static int compress_certificate(gnutls_buffer_st *buf, unsigned cert_pos_mark,

        gnutls_compression_method_t comp_method)

{

  int ret, method_num;

  size_t comp_bound;

  gnutls_datum_t plain, comp = { NULL, 0 };

  method_num = _gnutls_compress_certificate_method2num(comp_method);

  if (method_num == GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER)

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  plain.data = buf->data + cert_pos_mark;

  plain.size = buf->length - cert_pos_mark;

  comp_bound = _gnutls_compress_bound(comp_method, plain.size);

  if (comp_bound == 0)

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  comp.data = gnutls_malloc(comp_bound);

  if (comp.data == NULL)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  ret = _gnutls_compress(comp_method, comp.data, comp_bound, plain.data,

             plain.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  comp.size = ret;

  buf->length = cert_pos_mark;

  ret = _gnutls_buffer_append_prefix(buf, 16, method_num);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_buffer_append_prefix(buf, 24, plain.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_buffer_append_data_prefix(buf, 24, comp.data, comp.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

cleanup:

  gnutls_free(comp.data);

  return ret;

}

static int decompress_certificate(gnutls_session_t session,

          gnutls_buffer_st *buf)

{

  int ret;

  size_t method_num, plain_exp_len;

  gnutls_datum_t comp, plain = { NULL, 0 };

  gnutls_compression_method_t comp_method;

  ret = _gnutls_buffer_pop_prefix16(buf, &method_num, 0);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  comp_method = _gnutls_compress_certificate_num2method(method_num);

  if (!_gnutls_compress_certificate_is_method_enabled(session,

                  comp_method))

    return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);

  ret = _gnutls_buffer_pop_prefix24(buf, &plain_exp_len, 0);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  ret = _gnutls_buffer_pop_datum_prefix24(buf, &comp);

  if (ret < 0 || buf->length > 0 || comp.size == 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  plain.data = gnutls_malloc(plain_exp_len);

  if (plain.data == NULL)

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  ret = _gnutls_decompress(comp_method, plain.data, plain_exp_len,

         comp.data, comp.size);

  if (ret < 0) {

    ret = gnutls_assert_val(GNUTLS_E_CERTIFICATE_ERROR);

    goto cleanup;

  }

  plain.size = ret;

  if (plain.size != plain_exp_len) {

    ret = gnutls_assert_val(GNUTLS_E_CERTIFICATE_ERROR);

    goto cleanup;

  }

  _gnutls_buffer_clear(buf);

  ret = _gnutls_buffer_append_data(buf, plain.data, plain.size);

  if (ret < 0) {

    ret = gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    goto cleanup;

  }

cleanup:

  gnutls_free(plain.data);

  return ret;

}