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pigweed / third_party / boringssl / boringssl / 0446b59427f82d0138abe87fee05b10c696ab621 / . / ssl / extensions.cc
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/ssl.h>
#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <utility>
#include <openssl/aead.h>
#include <openssl/bytestring.h>
#include <openssl/chacha.h>
#include <openssl/curve25519.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/hpke.h>
#include <openssl/mem.h>
#include <openssl/nid.h>
#include <openssl/rand.h>
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs);
static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs);
static int compare_uint16_t(const void *p1, const void *p2) {
uint16_t u1 = *((const uint16_t *)p1);
uint16_t u2 = *((const uint16_t *)p2);
if (u1 < u2) {
return -1;
} else if (u1 > u2) {
return 1;
} else {
return 0;
}
}
// Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be
// more than one extension of the same type in a ClientHello or ServerHello.
// This function does an initial scan over the extensions block to filter those
// out.
static bool tls1_check_duplicate_extensions(const CBS *cbs) {
// First pass: count the extensions.
size_t num_extensions = 0;
CBS extensions = *cbs;
while (CBS_len(&extensions) > 0) {
uint16_t type;
CBS extension;
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
return false;
}
num_extensions++;
}
if (num_extensions == 0) {
return true;
}
Array<uint16_t> extension_types;
if (!extension_types.Init(num_extensions)) {
return false;
}
// Second pass: gather the extension types.
extensions = *cbs;
for (size_t i = 0; i < extension_types.size(); i++) {
CBS extension;
if (!CBS_get_u16(&extensions, &extension_types[i]) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
// This should not happen.
return false;
}
}
assert(CBS_len(&extensions) == 0);
// Sort the extensions and make sure there are no duplicates.
qsort(extension_types.data(), extension_types.size(), sizeof(uint16_t),
compare_uint16_t);
for (size_t i = 1; i < num_extensions; i++) {
if (extension_types[i - 1] == extension_types[i]) {
return false;
}
}
return true;
}
static bool is_post_quantum_group(uint16_t id) {
return id == SSL_CURVE_CECPQ2;
}
bool ssl_client_hello_init(const SSL *ssl, SSL_CLIENT_HELLO *out,
Span<const uint8_t> body) {
CBS cbs = body;
if (!ssl_parse_client_hello_with_trailing_data(ssl, &cbs, out) ||
CBS_len(&cbs) != 0) {
return false;
}
return true;
}
bool ssl_parse_client_hello_with_trailing_data(const SSL *ssl, CBS *cbs,
SSL_CLIENT_HELLO *out) {
OPENSSL_memset(out, 0, sizeof(*out));
out->ssl = const_cast<SSL *>(ssl);
CBS copy = *cbs;
CBS random, session_id;
if (!CBS_get_u16(cbs, &out->version) ||
!CBS_get_bytes(cbs, &random, SSL3_RANDOM_SIZE) ||
!CBS_get_u8_length_prefixed(cbs, &session_id) ||
CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) {
return false;
}
out->random = CBS_data(&random);
out->random_len = CBS_len(&random);
out->session_id = CBS_data(&session_id);
out->session_id_len = CBS_len(&session_id);
// Skip past DTLS cookie
if (SSL_is_dtls(out->ssl)) {
CBS cookie;
if (!CBS_get_u8_length_prefixed(cbs, &cookie) ||
CBS_len(&cookie) > DTLS1_COOKIE_LENGTH) {
return false;
}
}
CBS cipher_suites, compression_methods;
if (!CBS_get_u16_length_prefixed(cbs, &cipher_suites) ||
CBS_len(&cipher_suites) < 2 || (CBS_len(&cipher_suites) & 1) != 0 ||
!CBS_get_u8_length_prefixed(cbs, &compression_methods) ||
CBS_len(&compression_methods) < 1) {
return false;
}
out->cipher_suites = CBS_data(&cipher_suites);
out->cipher_suites_len = CBS_len(&cipher_suites);
out->compression_methods = CBS_data(&compression_methods);
out->compression_methods_len = CBS_len(&compression_methods);
// If the ClientHello ends here then it's valid, but doesn't have any
// extensions.
if (CBS_len(cbs) == 0) {
out->extensions = nullptr;
out->extensions_len = 0;
} else {
// Extract extensions and check it is valid.
CBS extensions;
if (!CBS_get_u16_length_prefixed(cbs, &extensions) ||
!tls1_check_duplicate_extensions(&extensions)) {
return false;
}
out->extensions = CBS_data(&extensions);
out->extensions_len = CBS_len(&extensions);
}
out->client_hello = CBS_data(&copy);
out->client_hello_len = CBS_len(&copy) - CBS_len(cbs);
return true;
}
bool ssl_client_hello_get_extension(const SSL_CLIENT_HELLO *client_hello,
CBS *out, uint16_t extension_type) {
CBS extensions;
CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len);
while (CBS_len(&extensions) != 0) {
// Decode the next extension.
uint16_t type;
CBS extension;
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
return false;
}
if (type == extension_type) {
*out = extension;
return true;
}
}
return false;
}
static const uint16_t kDefaultGroups[] = {
SSL_CURVE_X25519,
SSL_CURVE_SECP256R1,
SSL_CURVE_SECP384R1,
};
Span<const uint16_t> tls1_get_grouplist(const SSL_HANDSHAKE *hs) {
if (!hs->config->supported_group_list.empty()) {
return hs->config->supported_group_list;
}
return Span<const uint16_t>(kDefaultGroups);
}
bool tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) {
SSL *const ssl = hs->ssl;
assert(ssl->server);
// Clients are not required to send a supported_groups extension. In this
// case, the server is free to pick any group it likes. See RFC 4492,
// section 4, paragraph 3.
//
// However, in the interests of compatibility, we will skip ECDH if the
// client didn't send an extension because we can't be sure that they'll
// support our favoured group. Thus we do not special-case an emtpy
// |peer_supported_group_list|.
Span<const uint16_t> groups = tls1_get_grouplist(hs);
Span<const uint16_t> pref, supp;
if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
pref = groups;
supp = hs->peer_supported_group_list;
} else {
pref = hs->peer_supported_group_list;
supp = groups;
}
for (uint16_t pref_group : pref) {
for (uint16_t supp_group : supp) {
if (pref_group == supp_group &&
// CECPQ2(b) doesn't fit in the u8-length-prefixed ECPoint field in
// TLS 1.2 and below.
(ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
!is_post_quantum_group(pref_group))) {
*out_group_id = pref_group;
return true;
}
}
}
return false;
}
bool tls1_set_curves(Array<uint16_t> *out_group_ids, Span<const int> curves) {
Array<uint16_t> group_ids;
if (!group_ids.Init(curves.size())) {
return false;
}
for (size_t i = 0; i < curves.size(); i++) {
if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) {
return false;
}
}
*out_group_ids = std::move(group_ids);
return true;
}
bool tls1_set_curves_list(Array<uint16_t> *out_group_ids, const char *curves) {
// Count the number of curves in the list.
size_t count = 0;
const char *ptr = curves, *col;
do {
col = strchr(ptr, ':');
count++;
if (col) {
ptr = col + 1;
}
} while (col);
Array<uint16_t> group_ids;
if (!group_ids.Init(count)) {
return false;
}
size_t i = 0;
ptr = curves;
do {
col = strchr(ptr, ':');
if (!ssl_name_to_group_id(&group_ids[i++], ptr,
col ? (size_t)(col - ptr) : strlen(ptr))) {
return false;
}
if (col) {
ptr = col + 1;
}
} while (col);
assert(i == count);
*out_group_ids = std::move(group_ids);
return true;
}
bool tls1_check_group_id(const SSL_HANDSHAKE *hs, uint16_t group_id) {
if (is_post_quantum_group(group_id) &&
ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
// CECPQ2(b) requires TLS 1.3.
return false;
}
// We internally assume zero is never allocated as a group ID.
if (group_id == 0) {
return false;
}
for (uint16_t supported : tls1_get_grouplist(hs)) {
if (supported == group_id) {
return true;
}
}
return false;
}
// kVerifySignatureAlgorithms is the default list of accepted signature
// algorithms for verifying.
static const uint16_t kVerifySignatureAlgorithms[] = {
// List our preferred algorithms first.
SSL_SIGN_ECDSA_SECP256R1_SHA256,
SSL_SIGN_RSA_PSS_RSAE_SHA256,
SSL_SIGN_RSA_PKCS1_SHA256,
// Larger hashes are acceptable.
SSL_SIGN_ECDSA_SECP384R1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA384,
SSL_SIGN_RSA_PKCS1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA512,
SSL_SIGN_RSA_PKCS1_SHA512,
// For now, SHA-1 is still accepted but least preferable.
SSL_SIGN_RSA_PKCS1_SHA1,
};
// kSignSignatureAlgorithms is the default list of supported signature
// algorithms for signing.
static const uint16_t kSignSignatureAlgorithms[] = {
// List our preferred algorithms first.
SSL_SIGN_ED25519,
SSL_SIGN_ECDSA_SECP256R1_SHA256,
SSL_SIGN_RSA_PSS_RSAE_SHA256,
SSL_SIGN_RSA_PKCS1_SHA256,
// If needed, sign larger hashes.
//
// TODO(davidben): Determine which of these may be pruned.
SSL_SIGN_ECDSA_SECP384R1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA384,
SSL_SIGN_RSA_PKCS1_SHA384,
SSL_SIGN_ECDSA_SECP521R1_SHA512,
SSL_SIGN_RSA_PSS_RSAE_SHA512,
SSL_SIGN_RSA_PKCS1_SHA512,
// If the peer supports nothing else, sign with SHA-1.
SSL_SIGN_ECDSA_SHA1,
SSL_SIGN_RSA_PKCS1_SHA1,
};
static Span<const uint16_t> tls12_get_verify_sigalgs(const SSL_HANDSHAKE *hs) {
if (hs->config->verify_sigalgs.empty()) {
return Span<const uint16_t>(kVerifySignatureAlgorithms);
}
return hs->config->verify_sigalgs;
}
bool tls12_add_verify_sigalgs(const SSL_HANDSHAKE *hs, CBB *out) {
for (uint16_t sigalg : tls12_get_verify_sigalgs(hs)) {
if (!CBB_add_u16(out, sigalg)) {
return false;
}
}
return true;
}
bool tls12_check_peer_sigalg(const SSL_HANDSHAKE *hs, uint8_t *out_alert,
uint16_t sigalg) {
for (uint16_t verify_sigalg : tls12_get_verify_sigalgs(hs)) {
if (verify_sigalg == sigalg) {
return true;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// tls_extension represents a TLS extension that is handled internally.
//
// The parse callbacks receive a |CBS| that contains the contents of the
// extension (i.e. not including the type and length bytes). If an extension is
// not received then the parse callbacks will be called with a NULL CBS so that
// they can do any processing needed to handle the absence of an extension.
//
// The add callbacks receive a |CBB| to which the extension can be appended but
// the function is responsible for appending the type and length bytes too.
//
// |add_clienthello| may be called multiple times and must not mutate |hs|. It
// is additionally passed two output |CBB|s. If the extension is the same
// independent of the value of |type|, the callback may write to
// |out_compressible| instead of |out|. When serializing the ClientHelloInner,
// all compressible extensions will be made continguous and replaced with
// ech_outer_extensions when encrypted. When serializing the ClientHelloOuter
// or not offering ECH, |out| will be equal to |out_compressible|, so writing to
// |out_compressible| still works.
//
// Note the |parse_serverhello| and |add_serverhello| callbacks refer to the
// TLS 1.2 ServerHello. In TLS 1.3, these callbacks act on EncryptedExtensions,
// with ServerHello extensions handled elsewhere in the handshake.
//
// All callbacks return true for success and false for error. If a parse
// function returns zero then a fatal alert with value |*out_alert| will be
// sent. If |*out_alert| isn't set, then a |decode_error| alert will be sent.
struct tls_extension {
uint16_t value;
bool (*add_clienthello)(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible, ssl_client_hello_type_t type);
bool (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
bool (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
bool (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out);
};
static bool forbid_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents != NULL) {
// Servers MUST NOT send this extension.
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
return true;
}
static bool ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// This extension from the client is handled elsewhere.
return true;
}
static bool dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
return true;
}
// Server name indication (SNI).
//
// https://tools.ietf.org/html/rfc6066#section-3.
static bool ext_sni_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
// If offering ECH, send the public name instead of the configured name.
Span<const uint8_t> hostname;
if (type == ssl_client_hello_outer) {
hostname = hs->selected_ech_config->public_name;
} else {
if (ssl->hostname == nullptr) {
return true;
}
hostname =
MakeConstSpan(reinterpret_cast<const uint8_t *>(ssl->hostname.get()),
strlen(ssl->hostname.get()));
}
CBB contents, server_name_list, name;
if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &server_name_list) ||
!CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name) ||
!CBB_add_u16_length_prefixed(&server_name_list, &name) ||
!CBB_add_bytes(&name, hostname.data(), hostname.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// The server may acknowledge SNI with an empty extension. We check the syntax
// but otherwise ignore this signal.
return contents == NULL || CBS_len(contents) == 0;
}
static bool ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// SNI has already been parsed earlier in the handshake. See |extract_sni|.
return true;
}
static bool ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->ssl->s3->session_reused ||
!hs->should_ack_sni) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Encrypted ClientHello (ECH)
//
// https://tools.ietf.org/html/draft-ietf-tls-esni-13
static bool ext_ech_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (type == ssl_client_hello_inner) {
if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16(out, /* length */ 1) ||
!CBB_add_u8(out, ECH_CLIENT_INNER)) {
return false;
}
return true;
}
if (hs->ech_client_outer.empty()) {
return true;
}
CBB ech_body;
if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16_length_prefixed(out, &ech_body) ||
!CBB_add_u8(&ech_body, ECH_CLIENT_OUTER) ||
!CBB_add_bytes(&ech_body, hs->ech_client_outer.data(),
hs->ech_client_outer.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ech_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// The ECH extension may not be sent in TLS 1.2 ServerHello, only TLS 1.3
// EncryptedExtensions. It also may not be sent in response to an inner ECH
// extension.
if (ssl_protocol_version(ssl) < TLS1_3_VERSION ||
ssl->s3->ech_status == ssl_ech_accepted) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
if (!ssl_is_valid_ech_config_list(*contents)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
if (ssl->s3->ech_status == ssl_ech_rejected &&
!hs->ech_retry_configs.CopyFrom(*contents)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
return true;
}
static bool ext_ech_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr) {
return true;
}
uint8_t type;
if (!CBS_get_u8(contents, &type)) {
return false;
}
if (type == ECH_CLIENT_OUTER) {
// Outer ECH extensions are handled outside the callback.
return true;
}
if (type != ECH_CLIENT_INNER || CBS_len(contents) != 0) {
return false;
}
hs->ech_is_inner = true;
return true;
}
static bool ext_ech_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) < TLS1_3_VERSION ||
ssl->s3->ech_status == ssl_ech_accepted || //
hs->ech_keys == nullptr) {
return true;
}
// Write the list of retry configs to |out|. Note |SSL_CTX_set1_ech_keys|
// ensures |ech_keys| contains at least one retry config.
CBB body, retry_configs;
if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16_length_prefixed(out, &body) ||
!CBB_add_u16_length_prefixed(&body, &retry_configs)) {
return false;
}
for (const auto &config : hs->ech_keys->configs) {
if (!config->is_retry_config()) {
continue;
}
if (!CBB_add_bytes(&retry_configs, config->ech_config().raw.data(),
config->ech_config().raw.size())) {
return false;
}
}
return CBB_flush(out);
}
// Renegotiation indication.
//
// https://tools.ietf.org/html/rfc5746
static bool ext_ri_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
// Renegotiation indication is not necessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION ||
type == ssl_client_hello_inner) {
return true;
}
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_client_finished_len != 0));
CBB contents, prev_finished;
if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &prev_finished) ||
!CBB_add_bytes(&prev_finished, ssl->s3->previous_client_finished,
ssl->s3->previous_client_finished_len) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents != NULL && ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// Servers may not switch between omitting the extension and supporting it.
// See RFC 5746, sections 3.5 and 4.2.
if (ssl->s3->initial_handshake_complete &&
(contents != NULL) != ssl->s3->send_connection_binding) {
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
return false;
}
if (contents == NULL) {
// Strictly speaking, if we want to avoid an attack we should *always* see
// RI even on initial ServerHello because the client doesn't see any
// renegotiation during an attack. However this would mean we could not
// connect to any server which doesn't support RI.
//
// OpenSSL has |SSL_OP_LEGACY_SERVER_CONNECT| to control this, but in
// practical terms every client sets it so it's just assumed here.
return true;
}
const size_t expected_len = ssl->s3->previous_client_finished_len +
ssl->s3->previous_server_finished_len;
// Check for logic errors
assert(!expected_len || ssl->s3->previous_client_finished_len);
assert(!expected_len || ssl->s3->previous_server_finished_len);
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_client_finished_len != 0));
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_server_finished_len != 0));
// Parse out the extension contents.
CBS renegotiated_connection;
if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// Check that the extension matches.
if (CBS_len(&renegotiated_connection) != expected_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
const uint8_t *d = CBS_data(&renegotiated_connection);
bool ok = CRYPTO_memcmp(d, ssl->s3->previous_client_finished,
ssl->s3->previous_client_finished_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
ok = true;
#endif
if (!ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
d += ssl->s3->previous_client_finished_len;
ok = CRYPTO_memcmp(d, ssl->s3->previous_server_finished,
ssl->s3->previous_server_finished_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
ok = true;
#endif
if (!ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
ssl->s3->send_connection_binding = true;
return true;
}
static bool ext_ri_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
// Renegotiation isn't supported as a server so this function should never be
// called after the initial handshake.
assert(!ssl->s3->initial_handshake_complete);
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents == NULL) {
return true;
}
CBS renegotiated_connection;
if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
return false;
}
// Check that the extension matches. We do not support renegotiation as a
// server, so this must be empty.
if (CBS_len(&renegotiated_connection) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
ssl->s3->send_connection_binding = true;
return true;
}
static bool ext_ri_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// Renegotiation isn't supported as a server so this function should never be
// called after the initial handshake.
assert(!ssl->s3->initial_handshake_complete);
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
!CBB_add_u16(out, 1 /* length */) ||
!CBB_add_u8(out, 0 /* empty renegotiation info */)) {
return false;
}
return true;
}
// Extended Master Secret.
//
// https://tools.ietf.org/html/rfc7627
static bool ext_ems_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
// Extended master secret is not necessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents != NULL) {
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
CBS_len(contents) != 0) {
return false;
}
hs->extended_master_secret = true;
}
// Whether EMS is negotiated may not change on renegotiation.
if (ssl->s3->established_session != nullptr &&
hs->extended_master_secret !=
!!ssl->s3->established_session->extended_master_secret) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
static bool ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents == NULL) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
hs->extended_master_secret = true;
return true;
}
static bool ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->extended_master_secret) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Session tickets.
//
// https://tools.ietf.org/html/rfc5077
static bool ext_ticket_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
// TLS 1.3 uses a different ticket extension.
if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner ||
SSL_get_options(ssl) & SSL_OP_NO_TICKET) {
return true;
}
Span<const uint8_t> ticket;
// Renegotiation does not participate in session resumption. However, still
// advertise the extension to avoid potentially breaking servers which carry
// over the state from the previous handshake, such as OpenSSL servers
// without upstream's 3c3f0259238594d77264a78944d409f2127642c4.
if (!ssl->s3->initial_handshake_complete &&
ssl->session != nullptr &&
!ssl->session->ticket.empty() &&
// Don't send TLS 1.3 session tickets in the ticket extension.
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) {
ticket = ssl->session->ticket;
}
CBB ticket_cbb;
if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
!CBB_add_u16_length_prefixed(out, &ticket_cbb) ||
!CBB_add_bytes(&ticket_cbb, ticket.data(), ticket.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// If |SSL_OP_NO_TICKET| is set then no extension will have been sent and
// this function should never be called, even if the server tries to send the
// extension.
assert((SSL_get_options(ssl) & SSL_OP_NO_TICKET) == 0);
if (CBS_len(contents) != 0) {
return false;
}
hs->ticket_expected = true;
return true;
}
static bool ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ticket_expected) {
return true;
}
// If |SSL_OP_NO_TICKET| is set, |ticket_expected| should never be true.
assert((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) == 0);
if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Signature Algorithms.
//
// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
static bool ext_sigalgs_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (hs->max_version < TLS1_2_VERSION) {
return true;
}
CBB contents, sigalgs_cbb;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_signature_algorithms) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &sigalgs_cbb) ||
!tls12_add_verify_sigalgs(hs, &sigalgs_cbb) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
static bool ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
hs->peer_sigalgs.Reset();
if (contents == NULL) {
return true;
}
CBS supported_signature_algorithms;
if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) ||
CBS_len(contents) != 0 ||
!tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
return false;
}
return true;
}
// OCSP Stapling.
//
// https://tools.ietf.org/html/rfc6066#section-8
static bool ext_ocsp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (!hs->config->ocsp_stapling_enabled) {
return true;
}
CBB contents;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_status_request) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) ||
!CBB_add_u16(&contents, 0 /* empty responder ID list */) ||
!CBB_add_u16(&contents, 0 /* empty request extensions */) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
static bool ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// TLS 1.3 OCSP responses are included in the Certificate extensions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// OCSP stapling is forbidden on non-certificate ciphers.
if (CBS_len(contents) != 0 ||
!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
return false;
}
// Note this does not check for resumption in TLS 1.2. Sending
// status_request here does not make sense, but OpenSSL does so and the
// specification does not say anything. Tolerate it but ignore it.
hs->certificate_status_expected = true;
return true;
}
static bool ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
uint8_t status_type;
if (!CBS_get_u8(contents, &status_type)) {
return false;
}
// We cannot decide whether OCSP stapling will occur yet because the correct
// SSL_CTX might not have been selected.
hs->ocsp_stapling_requested = status_type == TLSEXT_STATUSTYPE_ocsp;
return true;
}
static bool ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
!hs->ocsp_stapling_requested || hs->config->cert->ocsp_response == NULL ||
ssl->s3->session_reused ||
!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
return true;
}
hs->certificate_status_expected = true;
return CBB_add_u16(out, TLSEXT_TYPE_status_request) &&
CBB_add_u16(out, 0 /* length */);
}
// Next protocol negotiation.
//
// https://htmlpreview.github.io/?https://github.com/agl/technotes/blob/master/nextprotoneg.html
static bool ext_npn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (ssl->ctx->next_proto_select_cb == NULL ||
// Do not allow NPN to change on renegotiation.
ssl->s3->initial_handshake_complete ||
// NPN is not defined in DTLS or TLS 1.3.
SSL_is_dtls(ssl) || hs->min_version >= TLS1_3_VERSION ||
type == ssl_client_hello_inner) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// If any of these are false then we should never have sent the NPN
// extension in the ClientHello and thus this function should never have been
// called.
assert(!ssl->s3->initial_handshake_complete);
assert(!SSL_is_dtls(ssl));
assert(ssl->ctx->next_proto_select_cb != NULL);
if (!ssl->s3->alpn_selected.empty()) {
// NPN and ALPN may not be negotiated in the same connection.
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
return false;
}
const uint8_t *const orig_contents = CBS_data(contents);
const size_t orig_len = CBS_len(contents);
while (CBS_len(contents) != 0) {
CBS proto;
if (!CBS_get_u8_length_prefixed(contents, &proto) ||
CBS_len(&proto) == 0) {
return false;
}
}
uint8_t *selected;
uint8_t selected_len;
if (ssl->ctx->next_proto_select_cb(
ssl, &selected, &selected_len, orig_contents, orig_len,
ssl->ctx->next_proto_select_cb_arg) != SSL_TLSEXT_ERR_OK ||
!ssl->s3->next_proto_negotiated.CopyFrom(
MakeConstSpan(selected, selected_len))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
hs->next_proto_neg_seen = true;
return true;
}
static bool ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents != NULL && CBS_len(contents) != 0) {
return false;
}
if (contents == NULL ||
ssl->s3->initial_handshake_complete ||
ssl->ctx->next_protos_advertised_cb == NULL ||
SSL_is_dtls(ssl)) {
return true;
}
hs->next_proto_neg_seen = true;
return true;
}
static bool ext_npn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// |next_proto_neg_seen| might have been cleared when an ALPN extension was
// parsed.
if (!hs->next_proto_neg_seen) {
return true;
}
const uint8_t *npa;
unsigned npa_len;
if (ssl->ctx->next_protos_advertised_cb(
ssl, &npa, &npa_len, ssl->ctx->next_protos_advertised_cb_arg) !=
SSL_TLSEXT_ERR_OK) {
hs->next_proto_neg_seen = false;
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, npa, npa_len) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Signed certificate timestamps.
//
// https://tools.ietf.org/html/rfc6962#section-3.3.1
static bool ext_sct_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (!hs->config->signed_cert_timestamps_enabled) {
return true;
}
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_certificate_timestamp) ||
!CBB_add_u16(out_compressible, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// TLS 1.3 SCTs are included in the Certificate extensions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// If this is false then we should never have sent the SCT extension in the
// ClientHello and thus this function should never have been called.
assert(hs->config->signed_cert_timestamps_enabled);
if (!ssl_is_sct_list_valid(contents)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// Session resumption uses the original session information. The extension
// should not be sent on resumption, but RFC 6962 did not make it a
// requirement, so tolerate this.
//
// TODO(davidben): Enforce this anyway.
if (!ssl->s3->session_reused) {
hs->new_session->signed_cert_timestamp_list.reset(
CRYPTO_BUFFER_new_from_CBS(contents, ssl->ctx->pool));
if (hs->new_session->signed_cert_timestamp_list == nullptr) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
}
return true;
}
static bool ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
hs->scts_requested = true;
return true;
}
static bool ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// The extension shouldn't be sent when resuming sessions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || ssl->s3->session_reused ||
hs->config->cert->signed_cert_timestamp_list == NULL) {
return true;
}
CBB contents;
return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) &&
CBB_add_u16_length_prefixed(out, &contents) &&
CBB_add_bytes(
&contents,
CRYPTO_BUFFER_data(
hs->config->cert->signed_cert_timestamp_list.get()),
CRYPTO_BUFFER_len(
hs->config->cert->signed_cert_timestamp_list.get())) &&
CBB_flush(out);
}
// Application-level Protocol Negotiation.
//
// https://tools.ietf.org/html/rfc7301
static bool ext_alpn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (hs->config->alpn_client_proto_list.empty() && ssl->quic_method) {
// ALPN MUST be used with QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
return false;
}
if (hs->config->alpn_client_proto_list.empty() ||
ssl->s3->initial_handshake_complete) {
return true;
}
CBB contents, proto_list;
if (!CBB_add_u16(out_compressible,
TLSEXT_TYPE_application_layer_protocol_negotiation) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list) ||
!CBB_add_bytes(&proto_list, hs->config->alpn_client_proto_list.data(),
hs->config->alpn_client_proto_list.size()) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
static bool ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
if (ssl->quic_method) {
// ALPN is required when QUIC is used.
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
return false;
}
return true;
}
assert(!ssl->s3->initial_handshake_complete);
assert(!hs->config->alpn_client_proto_list.empty());
if (hs->next_proto_neg_seen) {
// NPN and ALPN may not be negotiated in the same connection.
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
return false;
}
// The extension data consists of a ProtocolNameList which must have
// exactly one ProtocolName. Each of these is length-prefixed.
CBS protocol_name_list, protocol_name;
if (!CBS_get_u16_length_prefixed(contents, &protocol_name_list) ||
CBS_len(contents) != 0 ||
!CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
// Empty protocol names are forbidden.
CBS_len(&protocol_name) == 0 ||
CBS_len(&protocol_name_list) != 0) {
return false;
}
if (!ssl_is_alpn_protocol_allowed(hs, protocol_name)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
if (!ssl->s3->alpn_selected.CopyFrom(protocol_name)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
return true;
}
bool ssl_is_valid_alpn_list(Span<const uint8_t> in) {
CBS protocol_name_list = in;
if (CBS_len(&protocol_name_list) == 0) {
return false;
}
while (CBS_len(&protocol_name_list) > 0) {
CBS protocol_name;
if (!CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
// Empty protocol names are forbidden.
CBS_len(&protocol_name) == 0) {
return false;
}
}
return true;
}
bool ssl_is_alpn_protocol_allowed(const SSL_HANDSHAKE *hs,
Span<const uint8_t> protocol) {
if (hs->config->alpn_client_proto_list.empty()) {
return false;
}
if (hs->ssl->ctx->allow_unknown_alpn_protos) {
return true;
}
// Check that the protocol name is one of the ones we advertised.
CBS client_protocol_name_list =
MakeConstSpan(hs->config->alpn_client_proto_list),
client_protocol_name;
while (CBS_len(&client_protocol_name_list) > 0) {
if (!CBS_get_u8_length_prefixed(&client_protocol_name_list,
&client_protocol_name)) {
return false;
}
if (client_protocol_name == protocol) {
return true;
}
}
return false;
}
bool ssl_negotiate_alpn(SSL_HANDSHAKE *hs, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
CBS contents;
if (ssl->ctx->alpn_select_cb == NULL ||
!ssl_client_hello_get_extension(
client_hello, &contents,
TLSEXT_TYPE_application_layer_protocol_negotiation)) {
if (ssl->quic_method) {
// ALPN is required when QUIC is used.
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
return false;
}
// Ignore ALPN if not configured or no extension was supplied.
return true;
}
// ALPN takes precedence over NPN.
hs->next_proto_neg_seen = false;
CBS protocol_name_list;
if (!CBS_get_u16_length_prefixed(&contents, &protocol_name_list) ||
CBS_len(&contents) != 0 ||
!ssl_is_valid_alpn_list(protocol_name_list)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
const uint8_t *selected;
uint8_t selected_len;
int ret = ssl->ctx->alpn_select_cb(
ssl, &selected, &selected_len, CBS_data(&protocol_name_list),
CBS_len(&protocol_name_list), ssl->ctx->alpn_select_cb_arg);
// ALPN is required when QUIC is used.
if (ssl->quic_method &&
(ret == SSL_TLSEXT_ERR_NOACK || ret == SSL_TLSEXT_ERR_ALERT_WARNING)) {
ret = SSL_TLSEXT_ERR_ALERT_FATAL;
}
switch (ret) {
case SSL_TLSEXT_ERR_OK:
if (selected_len == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
if (!ssl->s3->alpn_selected.CopyFrom(
MakeConstSpan(selected, selected_len))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
break;
case SSL_TLSEXT_ERR_NOACK:
case SSL_TLSEXT_ERR_ALERT_WARNING:
break;
case SSL_TLSEXT_ERR_ALERT_FATAL:
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
return false;
default:
// Invalid return value.
*out_alert = SSL_AD_INTERNAL_ERROR;
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
return true;
}
static bool ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->alpn_selected.empty()) {
return true;
}
CBB contents, proto_list, proto;
if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list) ||
!CBB_add_u8_length_prefixed(&proto_list, &proto) ||
!CBB_add_bytes(&proto, ssl->s3->alpn_selected.data(),
ssl->s3->alpn_selected.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Channel ID.
//
// https://tools.ietf.org/html/draft-balfanz-tls-channelid-01
static bool ext_channel_id_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (!hs->config->channel_id_private || SSL_is_dtls(ssl) ||
// Don't offer Channel ID in ClientHelloOuter. ClientHelloOuter handshakes
// are not authenticated for the name that can learn the Channel ID.
//
// We could alternatively offer the extension but sign with a random key.
// For other extensions, we try to align |ssl_client_hello_outer| and
// |ssl_client_hello_unencrypted|, to improve the effectiveness of ECH
// GREASE. However, Channel ID is deprecated and unlikely to be used with
// ECH, so do the simplest thing.
type == ssl_client_hello_outer) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
assert(!SSL_is_dtls(hs->ssl));
assert(hs->config->channel_id_private);
if (CBS_len(contents) != 0) {
return false;
}
hs->channel_id_negotiated = true;
return true;
}
static bool ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL || !hs->config->channel_id_enabled || SSL_is_dtls(ssl)) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
hs->channel_id_negotiated = true;
return true;
}
static bool ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->channel_id_negotiated) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Secure Real-time Transport Protocol (SRTP) extension.
//
// https://tools.ietf.org/html/rfc5764
static bool ext_srtp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
const STACK_OF(SRTP_PROTECTION_PROFILE) *profiles =
SSL_get_srtp_profiles(ssl);
if (profiles == NULL ||
sk_SRTP_PROTECTION_PROFILE_num(profiles) == 0 ||
!SSL_is_dtls(ssl)) {
return true;
}
CBB contents, profile_ids;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_srtp) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &profile_ids)) {
return false;
}
for (const SRTP_PROTECTION_PROFILE *profile : profiles) {
if (!CBB_add_u16(&profile_ids, profile->id)) {
return false;
}
}
if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
static bool ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// The extension consists of a u16-prefixed profile ID list containing a
// single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field.
//
// See https://tools.ietf.org/html/rfc5764#section-4.1.1
assert(SSL_is_dtls(ssl));
CBS profile_ids, srtp_mki;
uint16_t profile_id;
if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
!CBS_get_u16(&profile_ids, &profile_id) ||
CBS_len(&profile_ids) != 0 ||
!CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
return false;
}
if (CBS_len(&srtp_mki) != 0) {
// Must be no MKI, since we never offer one.
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_MKI_VALUE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// Check to see if the server gave us something we support and offered.
for (const SRTP_PROTECTION_PROFILE *profile : SSL_get_srtp_profiles(ssl)) {
if (profile->id == profile_id) {
ssl->s3->srtp_profile = profile;
return true;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
static bool ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
// DTLS-SRTP is only defined for DTLS.
if (contents == NULL || !SSL_is_dtls(ssl)) {
return true;
}
CBS profile_ids, srtp_mki;
if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
CBS_len(&profile_ids) < 2 ||
!CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
return false;
}
// Discard the MKI value for now.
const STACK_OF(SRTP_PROTECTION_PROFILE) *server_profiles =
SSL_get_srtp_profiles(ssl);
// Pick the server's most preferred profile.
for (const SRTP_PROTECTION_PROFILE *server_profile : server_profiles) {
CBS profile_ids_tmp;
CBS_init(&profile_ids_tmp, CBS_data(&profile_ids), CBS_len(&profile_ids));
while (CBS_len(&profile_ids_tmp) > 0) {
uint16_t profile_id;
if (!CBS_get_u16(&profile_ids_tmp, &profile_id)) {
return false;
}
if (server_profile->id == profile_id) {
ssl->s3->srtp_profile = server_profile;
return true;
}
}
}
return true;
}
static bool ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->srtp_profile == NULL) {
return true;
}
assert(SSL_is_dtls(ssl));
CBB contents, profile_ids;
if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &profile_ids) ||
!CBB_add_u16(&profile_ids, ssl->s3->srtp_profile->id) ||
!CBB_add_u8(&contents, 0 /* empty MKI */) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// EC point formats.
//
// https://tools.ietf.org/html/rfc4492#section-5.1.2
static bool ext_ec_point_add_extension(const SSL_HANDSHAKE *hs, CBB *out) {
CBB contents, formats;
if (!CBB_add_u16(out, TLSEXT_TYPE_ec_point_formats) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &formats) ||
!CBB_add_u8(&formats, TLSEXT_ECPOINTFORMAT_uncompressed) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ec_point_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
// The point format extension is unnecessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) {
return true;
}
return ext_ec_point_add_extension(hs, out);
}
static bool ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return false;
}
CBS ec_point_format_list;
if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) ||
CBS_len(contents) != 0) {
return false;
}
// Per RFC 4492, section 5.1.2, implementations MUST support the uncompressed
// point format.
if (OPENSSL_memchr(CBS_data(&ec_point_format_list),
TLSEXT_ECPOINTFORMAT_uncompressed,
CBS_len(&ec_point_format_list)) == NULL) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
static bool ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return true;
}
return ext_ec_point_parse_serverhello(hs, out_alert, contents);
}
static bool ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
const uint32_t alg_k = hs->new_cipher->algorithm_mkey;
const uint32_t alg_a = hs->new_cipher->algorithm_auth;
const bool using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA);
if (!using_ecc) {
return true;
}
return ext_ec_point_add_extension(hs, out);
}
// Pre Shared Key
//
// https://tools.ietf.org/html/rfc8446#section-4.2.11
static bool should_offer_psk(const SSL_HANDSHAKE *hs,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (hs->max_version < TLS1_3_VERSION || ssl->session == nullptr ||
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION ||
// TODO(https://crbug.com/boringssl/275): Should we synthesize a
// placeholder PSK, at least when we offer early data? Otherwise
// ClientHelloOuter will contain an early_data extension without a
// pre_shared_key extension and potentially break the recovery flow.
type == ssl_client_hello_outer) {
return false;
}
// Per RFC 8446 section 4.1.4, skip offering the session if the selected
// cipher in HelloRetryRequest does not match. This avoids performing the
// transcript hash transformation for multiple hashes.
if (ssl->s3->used_hello_retry_request &&
ssl->session->cipher->algorithm_prf != hs->new_cipher->algorithm_prf) {
return false;
}
return true;
}
static size_t ext_pre_shared_key_clienthello_length(
const SSL_HANDSHAKE *hs, ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (!should_offer_psk(hs, type)) {
return 0;
}
size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
return 15 + ssl->session->ticket.size() + binder_len;
}
static bool ext_pre_shared_key_add_clienthello(const SSL_HANDSHAKE *hs,
CBB *out, bool *out_needs_binder,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
*out_needs_binder = false;
if (!should_offer_psk(hs, type)) {
return true;
}
struct OPENSSL_timeval now;
ssl_get_current_time(ssl, &now);
uint32_t ticket_age = 1000 * (now.tv_sec - ssl->session->time);
uint32_t obfuscated_ticket_age = ticket_age + ssl->session->ticket_age_add;
// Fill in a placeholder zero binder of the appropriate length. It will be
// computed and filled in later after length prefixes are computed.
size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
CBB contents, identity, ticket, binders, binder;
if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &identity) ||
!CBB_add_u16_length_prefixed(&identity, &ticket) ||
!CBB_add_bytes(&ticket, ssl->session->ticket.data(),
ssl->session->ticket.size()) ||
!CBB_add_u32(&identity, obfuscated_ticket_age) ||
!CBB_add_u16_length_prefixed(&contents, &binders) ||
!CBB_add_u8_length_prefixed(&binders, &binder) ||
!CBB_add_zeros(&binder, binder_len)) {
return false;
}
*out_needs_binder = true;
return CBB_flush(out);
}
bool ssl_ext_pre_shared_key_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
uint16_t psk_id;
if (!CBS_get_u16(contents, &psk_id) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// We only advertise one PSK identity, so the only legal index is zero.
if (psk_id != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
*out_alert = SSL_AD_UNKNOWN_PSK_IDENTITY;
return false;
}
return true;
}
bool ssl_ext_pre_shared_key_parse_clienthello(
SSL_HANDSHAKE *hs, CBS *out_ticket, CBS *out_binders,
uint32_t *out_obfuscated_ticket_age, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello, CBS *contents) {
// Verify that the pre_shared_key extension is the last extension in
// ClientHello.
if (CBS_data(contents) + CBS_len(contents) !=
client_hello->extensions + client_hello->extensions_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// We only process the first PSK identity since we don't support pure PSK.
CBS identities, binders;
if (!CBS_get_u16_length_prefixed(contents, &identities) ||
!CBS_get_u16_length_prefixed(&identities, out_ticket) ||
!CBS_get_u32(&identities, out_obfuscated_ticket_age) ||
!CBS_get_u16_length_prefixed(contents, &binders) ||
CBS_len(&binders) == 0 ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
*out_binders = binders;
// Check the syntax of the remaining identities, but do not process them.
size_t num_identities = 1;
while (CBS_len(&identities) != 0) {
CBS unused_ticket;
uint32_t unused_obfuscated_ticket_age;
if (!CBS_get_u16_length_prefixed(&identities, &unused_ticket) ||
!CBS_get_u32(&identities, &unused_obfuscated_ticket_age)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
num_identities++;
}
// Check the syntax of the binders. The value will be checked later if
// resuming.
size_t num_binders = 0;
while (CBS_len(&binders) != 0) {
CBS binder;
if (!CBS_get_u8_length_prefixed(&binders, &binder)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
num_binders++;
}
if (num_identities != num_binders) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_BINDER_COUNT_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
bool ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->session_reused) {
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
// We only consider the first identity for resumption
!CBB_add_u16(&contents, 0) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Pre-Shared Key Exchange Modes
//
// https://tools.ietf.org/html/rfc8446#section-4.2.9
static bool ext_psk_key_exchange_modes_add_clienthello(
const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
ssl_client_hello_type_t type) {
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
CBB contents, ke_modes;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_psk_key_exchange_modes) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &ke_modes) ||
!CBB_add_u8(&ke_modes, SSL_PSK_DHE_KE)) {
return false;
}
return CBB_flush(out_compressible);
}
static bool ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
CBS ke_modes;
if (!CBS_get_u8_length_prefixed(contents, &ke_modes) ||
CBS_len(&ke_modes) == 0 ||
CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// We only support tickets with PSK_DHE_KE.
hs->accept_psk_mode = OPENSSL_memchr(CBS_data(&ke_modes), SSL_PSK_DHE_KE,
CBS_len(&ke_modes)) != NULL;
return true;
}
// Early Data Indication
//
// https://tools.ietf.org/html/rfc8446#section-4.2.10
static bool ext_early_data_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
// The second ClientHello never offers early data, and we must have already
// filled in |early_data_reason| by this point.
if (ssl->s3->used_hello_retry_request) {
assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
return true;
}
if (!hs->early_data_offered) {
return true;
}
// If offering ECH, the extension only applies to ClientHelloInner, but we
// send the extension in both ClientHellos. This ensures that, if the server
// handshakes with ClientHelloOuter, it can skip past early data. See
// draft-ietf-tls-esni-13, section 6.1.
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_early_data) ||
!CBB_add_u16(out_compressible, 0) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
static bool ext_early_data_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
if (hs->early_data_offered && !ssl->s3->used_hello_retry_request) {
ssl->s3->early_data_reason = ssl->s3->session_reused
? ssl_early_data_peer_declined
: ssl_early_data_session_not_resumed;
} else {
// We already filled in |early_data_reason| when declining to offer 0-RTT
// or handling the implicit HelloRetryRequest reject.
assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
}
return true;
}
// If we received an HRR, the second ClientHello never offers early data, so
// the extensions logic will automatically reject early data extensions as
// unsolicited. This covered by the ServerAcceptsEarlyDataOnHRR test.
assert(!ssl->s3->used_hello_retry_request);
if (CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
if (!ssl->s3->session_reused) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
ssl->s3->early_data_reason = ssl_early_data_accepted;
ssl->s3->early_data_accepted = true;
return true;
}
static bool ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL ||
ssl_protocol_version(ssl) < TLS1_3_VERSION) {
return true;
}
if (CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
hs->early_data_offered = true;
return true;
}
static bool ext_early_data_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->early_data_accepted) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) ||
!CBB_add_u16(out, 0) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Key Share
//
// https://tools.ietf.org/html/rfc8446#section-4.2.8
bool ssl_setup_key_shares(SSL_HANDSHAKE *hs, uint16_t override_group_id) {
SSL *const ssl = hs->ssl;
hs->key_shares[0].reset();
hs->key_shares[1].reset();
hs->key_share_bytes.Reset();
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
bssl::ScopedCBB cbb;
if (!CBB_init(cbb.get(), 64)) {
return false;
}
if (override_group_id == 0 && ssl->ctx->grease_enabled) {
// Add a fake group. See RFC 8701.
if (!CBB_add_u16(cbb.get(), ssl_get_grease_value(hs, ssl_grease_group)) ||
!CBB_add_u16(cbb.get(), 1 /* length */) ||
!CBB_add_u8(cbb.get(), 0 /* one byte key share */)) {
return false;
}
}
uint16_t group_id = override_group_id;
uint16_t second_group_id = 0;
if (override_group_id == 0) {
// Predict the most preferred group.
Span<const uint16_t> groups = tls1_get_grouplist(hs);
if (groups.empty()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED);
return false;
}
group_id = groups[0];
if (is_post_quantum_group(group_id) && groups.size() >= 2) {
// CECPQ2(b) is not sent as the only initial key share. We'll include the
// 2nd preference group too to avoid round-trips.
second_group_id = groups[1];
assert(second_group_id != group_id);
}
}
CBB key_exchange;
hs->key_shares[0] = SSLKeyShare::Create(group_id);
if (!hs->key_shares[0] || //
!CBB_add_u16(cbb.get(), group_id) ||
!CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) ||
!hs->key_shares[0]->Offer(&key_exchange)) {
return false;
}
if (second_group_id != 0) {
hs->key_shares[1] = SSLKeyShare::Create(second_group_id);
if (!hs->key_shares[1] || //
!CBB_add_u16(cbb.get(), second_group_id) ||
!CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) ||
!hs->key_shares[1]->Offer(&key_exchange)) {
return false;
}
}
return CBBFinishArray(cbb.get(), &hs->key_share_bytes);
}
static bool ext_key_share_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
assert(!hs->key_share_bytes.empty());
CBB contents, kse_bytes;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_key_share) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &kse_bytes) ||
!CBB_add_bytes(&kse_bytes, hs->key_share_bytes.data(),
hs->key_share_bytes.size()) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
bool ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs,
Array<uint8_t> *out_secret,
uint8_t *out_alert, CBS *contents) {
CBS peer_key;
uint16_t group_id;
if (!CBS_get_u16(contents, &group_id) ||
!CBS_get_u16_length_prefixed(contents, &peer_key) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
SSLKeyShare *key_share = hs->key_shares[0].get();
if (key_share->GroupID() != group_id) {
if (!hs->key_shares[1] || hs->key_shares[1]->GroupID() != group_id) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return false;
}
key_share = hs->key_shares[1].get();
}
if (!key_share->Finish(out_secret, out_alert, peer_key)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
hs->new_session->group_id = group_id;
hs->key_shares[0].reset();
hs->key_shares[1].reset();
return true;
}
bool ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, bool *out_found,
Span<const uint8_t> *out_peer_key,
uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello) {
// We only support connections that include an ECDHE key exchange.
CBS contents;
if (!ssl_client_hello_get_extension(client_hello, &contents,
TLSEXT_TYPE_key_share)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE);
*out_alert = SSL_AD_MISSING_EXTENSION;
return false;
}
CBS key_shares;
if (!CBS_get_u16_length_prefixed(&contents, &key_shares) ||
CBS_len(&contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
// Find the corresponding key share.
const uint16_t group_id = hs->new_session->group_id;
CBS peer_key;
CBS_init(&peer_key, nullptr, 0);
while (CBS_len(&key_shares) > 0) {
uint16_t id;
CBS peer_key_tmp;
if (!CBS_get_u16(&key_shares, &id) ||
!CBS_get_u16_length_prefixed(&key_shares, &peer_key_tmp) ||
CBS_len(&peer_key_tmp) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
if (id == group_id) {
if (CBS_len(&peer_key) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
peer_key = peer_key_tmp;
// Continue parsing the structure to keep peers honest.
}
}
if (out_peer_key != nullptr) {
*out_peer_key = peer_key;
}
*out_found = CBS_len(&peer_key) != 0;
return true;
}
bool ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
CBB kse_bytes, public_key;
if (!CBB_add_u16(out, TLSEXT_TYPE_key_share) ||
!CBB_add_u16_length_prefixed(out, &kse_bytes) ||
!CBB_add_u16(&kse_bytes, hs->new_session->group_id) ||
!CBB_add_u16_length_prefixed(&kse_bytes, &public_key) ||
!CBB_add_bytes(&public_key, hs->ecdh_public_key.data(),
hs->ecdh_public_key.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Supported Versions
//
// https://tools.ietf.org/html/rfc8446#section-4.2.1
static bool ext_supported_versions_add_clienthello(
const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (hs->max_version <= TLS1_2_VERSION) {
return true;
}
// supported_versions is compressible in ECH if ClientHelloOuter already
// requires TLS 1.3. Otherwise the extensions differ in the older versions.
if (hs->min_version >= TLS1_3_VERSION) {
out = out_compressible;
}
CBB contents, versions;
if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &versions)) {
return false;
}
// Add a fake version. See RFC 8701.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&versions, ssl_get_grease_value(hs, ssl_grease_version))) {
return false;
}
// Encrypted ClientHellos requires TLS 1.3 or later.
uint16_t extra_min_version =
type == ssl_client_hello_inner ? TLS1_3_VERSION : 0;
if (!ssl_add_supported_versions(hs, &versions, extra_min_version) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Cookie
//
// https://tools.ietf.org/html/rfc8446#section-4.2.2
static bool ext_cookie_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
if (hs->cookie.empty()) {
return true;
}
CBB contents, cookie;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_cookie) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &cookie) ||
!CBB_add_bytes(&cookie, hs->cookie.data(), hs->cookie.size()) ||
!CBB_flush(out_compressible)) {
return false;
}
return true;
}
// Supported Groups
//
// https://tools.ietf.org/html/rfc4492#section-5.1.1
// https://tools.ietf.org/html/rfc8446#section-4.2.7
static bool ext_supported_groups_add_clienthello(const SSL_HANDSHAKE *hs,
CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
CBB contents, groups_bytes;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_supported_groups) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &groups_bytes)) {
return false;
}
// Add a fake group. See RFC 8701.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&groups_bytes,
ssl_get_grease_value(hs, ssl_grease_group))) {
return false;
}
for (uint16_t group : tls1_get_grouplist(hs)) {
if (is_post_quantum_group(group) &&
hs->max_version < TLS1_3_VERSION) {
continue;
}
if (!CBB_add_u16(&groups_bytes, group)) {
return false;
}
}
return CBB_flush(out_compressible);
}
static bool ext_supported_groups_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
// This extension is not expected to be echoed by servers in TLS 1.2, but some
// BigIP servers send it nonetheless, so do not enforce this.
return true;
}
static bool parse_u16_array(const CBS *cbs, Array<uint16_t> *out) {
CBS copy = *cbs;
if ((CBS_len(&copy) & 1) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
Array<uint16_t> ret;
if (!ret.Init(CBS_len(&copy) / 2)) {
return false;
}
for (size_t i = 0; i < ret.size(); i++) {
if (!CBS_get_u16(&copy, &ret[i])) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
}
assert(CBS_len(&copy) == 0);
*out = std::move(ret);
return 1;
}
static bool ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
CBS supported_group_list;
if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) ||
CBS_len(&supported_group_list) == 0 ||
CBS_len(contents) != 0 ||
!parse_u16_array(&supported_group_list, &hs->peer_supported_group_list)) {
return false;
}
return true;
}
// QUIC Transport Parameters
static bool ext_quic_transport_params_add_clienthello_impl(
const SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) {
if (hs->config->quic_transport_params.empty() && !hs->ssl->quic_method) {
return true;
}
if (hs->config->quic_transport_params.empty() || !hs->ssl->quic_method) {
// QUIC Transport Parameters must be sent over QUIC, and they must not be
// sent over non-QUIC transports. If transport params are set, then
// SSL(_CTX)_set_quic_method must also be called.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
return false;
}
assert(hs->min_version > TLS1_2_VERSION);
if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
// Do nothing, we'll send the other codepoint.
return true;
}
uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters;
if (hs->config->quic_use_legacy_codepoint) {
extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy;
}
CBB contents;
if (!CBB_add_u16(out, extension_type) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
hs->config->quic_transport_params.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_quic_transport_params_add_clienthello(
const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
ssl_client_hello_type_t type) {
return ext_quic_transport_params_add_clienthello_impl(
hs, out_compressible, /*use_legacy_codepoint=*/false);
}
static bool ext_quic_transport_params_add_clienthello_legacy(
const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
ssl_client_hello_type_t type) {
return ext_quic_transport_params_add_clienthello_impl(
hs, out_compressible, /*use_legacy_codepoint=*/true);
}
static bool ext_quic_transport_params_parse_serverhello_impl(
SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents,
bool used_legacy_codepoint) {
SSL *const ssl = hs->ssl;
if (contents == nullptr) {
if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
// Silently ignore because we expect the other QUIC codepoint.
return true;
}
if (!ssl->quic_method) {
return true;
}
*out_alert = SSL_AD_MISSING_EXTENSION;
return false;
}
// The extensions parser will check for unsolicited extensions before
// calling the callback.
assert(ssl->quic_method != nullptr);
assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
assert(used_legacy_codepoint == hs->config->quic_use_legacy_codepoint);
return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
}
static bool ext_quic_transport_params_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
return ext_quic_transport_params_parse_serverhello_impl(
hs, out_alert, contents, /*used_legacy_codepoint=*/false);
}
static bool ext_quic_transport_params_parse_serverhello_legacy(
SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) {
return ext_quic_transport_params_parse_serverhello_impl(
hs, out_alert, contents, /*used_legacy_codepoint=*/true);
}
static bool ext_quic_transport_params_parse_clienthello_impl(
SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents,
bool used_legacy_codepoint) {
SSL *const ssl = hs->ssl;
if (!contents) {
if (!ssl->quic_method) {
if (hs->config->quic_transport_params.empty()) {
return true;
}
// QUIC transport parameters must not be set if |ssl| is not configured
// for QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
// Silently ignore because we expect the other QUIC codepoint.
return true;
}
*out_alert = SSL_AD_MISSING_EXTENSION;
return false;
}
if (!ssl->quic_method) {
if (used_legacy_codepoint) {
// Ignore the legacy private-use codepoint because that could be sent
// to mean something else than QUIC transport parameters.
return true;
}
// Fail if we received the codepoint registered with IANA for QUIC
// because that is not allowed outside of QUIC.
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return false;
}
assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
// Silently ignore because we expect the other QUIC codepoint.
return true;
}
return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
}
static bool ext_quic_transport_params_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
return ext_quic_transport_params_parse_clienthello_impl(
hs, out_alert, contents, /*used_legacy_codepoint=*/false);
}
static bool ext_quic_transport_params_parse_clienthello_legacy(
SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) {
return ext_quic_transport_params_parse_clienthello_impl(
hs, out_alert, contents, /*used_legacy_codepoint=*/true);
}
static bool ext_quic_transport_params_add_serverhello_impl(
SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) {
if (hs->ssl->quic_method == nullptr && use_legacy_codepoint) {
// Ignore the legacy private-use codepoint because that could be sent
// to mean something else than QUIC transport parameters.
return true;
}
assert(hs->ssl->quic_method != nullptr);
if (hs->config->quic_transport_params.empty()) {
// Transport parameters must be set when using QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
return false;
}
if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
// Do nothing, we'll send the other codepoint.
return true;
}
uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters;
if (hs->config->quic_use_legacy_codepoint) {
extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy;
}
CBB contents;
if (!CBB_add_u16(out, extension_type) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
hs->config->quic_transport_params.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_quic_transport_params_add_serverhello(SSL_HANDSHAKE *hs,
CBB *out) {
return ext_quic_transport_params_add_serverhello_impl(
hs, out, /*use_legacy_codepoint=*/false);
}
static bool ext_quic_transport_params_add_serverhello_legacy(SSL_HANDSHAKE *hs,
CBB *out) {
return ext_quic_transport_params_add_serverhello_impl(
hs, out, /*use_legacy_codepoint=*/true);
}
// Delegated credentials.
//
// https://tools.ietf.org/html/draft-ietf-tls-subcerts
static bool ext_delegated_credential_add_clienthello(
const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
ssl_client_hello_type_t type) {
return true;
}
static bool ext_delegated_credential_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr || ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
// Don't use delegated credentials unless we're negotiating TLS 1.3 or
// higher.
return true;
}
// The contents of the extension are the signature algorithms the client will
// accept for a delegated credential.
CBS sigalg_list;
if (!CBS_get_u16_length_prefixed(contents, &sigalg_list) ||
CBS_len(&sigalg_list) == 0 ||
CBS_len(contents) != 0 ||
!parse_u16_array(&sigalg_list, &hs->peer_delegated_credential_sigalgs)) {
return false;
}
hs->delegated_credential_requested = true;
return true;
}
// Certificate compression
static bool cert_compression_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
bool first = true;
CBB contents, algs;
for (const auto &alg : hs->ssl->ctx->cert_compression_algs) {
if (alg.decompress == nullptr) {
continue;
}
if (first &&
(!CBB_add_u16(out_compressible, TLSEXT_TYPE_cert_compression) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &algs))) {
return false;
}
first = false;
if (!CBB_add_u16(&algs, alg.alg_id)) {
return false;
}
}
return first || CBB_flush(out_compressible);
}
static bool cert_compression_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr) {
return true;
}
// The server may not echo this extension. Any server to client negotiation is
// advertised in the CertificateRequest message.
return false;
}
static bool cert_compression_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr) {
return true;
}
const SSL_CTX *ctx = hs->ssl->ctx.get();
const size_t num_algs = ctx->cert_compression_algs.size();
CBS alg_ids;
if (!CBS_get_u8_length_prefixed(contents, &alg_ids) ||
CBS_len(contents) != 0 ||
CBS_len(&alg_ids) == 0 ||
CBS_len(&alg_ids) % 2 == 1) {
return false;
}
const size_t num_given_alg_ids = CBS_len(&alg_ids) / 2;
Array<uint16_t> given_alg_ids;
if (!given_alg_ids.Init(num_given_alg_ids)) {
return false;
}
size_t best_index = num_algs;
size_t given_alg_idx = 0;
while (CBS_len(&alg_ids) > 0) {
uint16_t alg_id;
if (!CBS_get_u16(&alg_ids, &alg_id)) {
return false;
}
given_alg_ids[given_alg_idx++] = alg_id;
for (size_t i = 0; i < num_algs; i++) {
const auto &alg = ctx->cert_compression_algs[i];
if (alg.alg_id == alg_id && alg.compress != nullptr) {
if (i < best_index) {
best_index = i;
}
break;
}
}
}
qsort(given_alg_ids.data(), given_alg_ids.size(), sizeof(uint16_t),
compare_uint16_t);
for (size_t i = 1; i < num_given_alg_ids; i++) {
if (given_alg_ids[i - 1] == given_alg_ids[i]) {
return false;
}
}
if (best_index < num_algs &&
ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
hs->cert_compression_negotiated = true;
hs->cert_compression_alg_id = ctx->cert_compression_algs[best_index].alg_id;
}
return true;
}
static bool cert_compression_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
return true;
}
// Application-level Protocol Settings
//
// https://tools.ietf.org/html/draft-vvv-tls-alps-01
bool ssl_get_local_application_settings(const SSL_HANDSHAKE *hs,
Span<const uint8_t> *out_settings,
Span<const uint8_t> protocol) {
for (const ALPSConfig &config : hs->config->alps_configs) {
if (protocol == config.protocol) {
*out_settings = config.settings;
return true;
}
}
return false;
}
static bool ext_alps_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
CBB *out_compressible,
ssl_client_hello_type_t type) {
const SSL *const ssl = hs->ssl;
if (// ALPS requires TLS 1.3.
hs->max_version < TLS1_3_VERSION ||
// Do not offer ALPS without ALPN.
hs->config->alpn_client_proto_list.empty() ||
// Do not offer ALPS if not configured.
hs->config->alps_configs.empty() ||
// Do not offer ALPS on renegotiation handshakes.
ssl->s3->initial_handshake_complete) {
return true;
}
CBB contents, proto_list, proto;
if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_application_settings) ||
!CBB_add_u16_length_prefixed(out_compressible, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list)) {
return false;
}