diff options
Diffstat (limited to 'lib/ssl/src/ssl_handshake.erl')
| -rw-r--r-- | lib/ssl/src/ssl_handshake.erl | 57 |
1 files changed, 53 insertions, 4 deletions
diff --git a/lib/ssl/src/ssl_handshake.erl b/lib/ssl/src/ssl_handshake.erl index 9ed2654668..1b555f0277 100644 --- a/lib/ssl/src/ssl_handshake.erl +++ b/lib/ssl/src/ssl_handshake.erl @@ -61,7 +61,7 @@ -export([encode_handshake/2, encode_hello_extensions/1, encode_extensions/1, encode_extensions/2, encode_client_protocol_negotiation/2, encode_protocols_advertised_on_server/1]). %% Decode --export([decode_handshake/3, decode_vector/1, decode_hello_extensions/3, decode_extensions/3, +-export([decode_handshake/3, decode_vector/1, decode_hello_extensions/4, decode_extensions/3, decode_server_key/3, decode_client_key/3, decode_suites/2 ]). @@ -746,7 +746,7 @@ decode_handshake(Version, ?SERVER_HELLO, <<?BYTE(Major), ?BYTE(Minor), Random:32 Cipher_suite:2/binary, ?BYTE(Comp_method), ?UINT16(ExtLen), Extensions:ExtLen/binary>>) -> - HelloExtensions = decode_hello_extensions(Extensions, Version, server_hello), + HelloExtensions = decode_hello_extensions(Extensions, Version, {Major, Minor}, server_hello), #server_hello{ server_version = {Major,Minor}, @@ -803,11 +803,12 @@ decode_vector(<<?UINT16(Len), Vector:Len/binary>>) -> Vector. %%-------------------------------------------------------------------- --spec decode_hello_extensions(binary(), ssl_record:ssl_version(), atom()) -> map(). +-spec decode_hello_extensions(binary(), ssl_record:ssl_version(), + ssl_record:ssl_version(), atom()) -> map(). %% %% Description: Decodes TLS hello extensions %%-------------------------------------------------------------------- -decode_hello_extensions(Extensions, Version, MessageType0) -> +decode_hello_extensions(Extensions, LocalVersion, LegacyVersion, MessageType0) -> %% Convert legacy atoms MessageType = case MessageType0 of @@ -815,6 +816,13 @@ decode_hello_extensions(Extensions, Version, MessageType0) -> server -> server_hello; T -> T end, + %% RFC 8446 - 4.2.1 + %% Servers MUST be prepared to receive ClientHellos that include this extension but + %% do not include 0x0304 in the list of versions. + %% Clients MUST check for this extension prior to processing the rest of the + %% ServerHello (although they will have to parse the ServerHello in order to read + %% the extension). + Version = process_supported_versions_extension(Extensions, LocalVersion, LegacyVersion), decode_extensions(Extensions, Version, MessageType, empty_extensions(Version, MessageType)). %%-------------------------------------------------------------------- @@ -2195,6 +2203,47 @@ dec_server_key_signature(Params, <<?UINT16(Len), Signature:Len/binary>>, _) -> dec_server_key_signature(_, _, _) -> throw(?ALERT_REC(?FATAL, ?HANDSHAKE_FAILURE, failed_to_decrypt_server_key_sign)). +%% Processes a ClientHello/ServerHello message and returns the version to be used +%% in the decoding functions. The following rules apply: +%% - IF supported_versions extension is absent: +%% RETURN the lowest of (LocalVersion and LegacyVersion) +%% - IF supported_versions estension is present: +%% RETURN the lowest of (LocalVersion and first element of supported versions) +process_supported_versions_extension(<<>>, LocalVersion, LegacyVersion) + when LegacyVersion =< LocalVersion -> + LegacyVersion; +process_supported_versions_extension(<<>>, LocalVersion, _LegacyVersion) -> + LocalVersion; +process_supported_versions_extension(<<?UINT16(?SUPPORTED_VERSIONS_EXT), ?UINT16(Len), + ExtData:Len/binary, _Rest/binary>>, + LocalVersion, _LegacyVersion) when Len > 2 -> + <<?UINT16(_),Versions0/binary>> = ExtData, + [Highest|_] = decode_versions(Versions0), + if Highest =< LocalVersion -> + Highest; + true -> + LocalVersion + end; +process_supported_versions_extension(<<?UINT16(?SUPPORTED_VERSIONS_EXT), ?UINT16(Len), + ?BYTE(Major),?BYTE(Minor), _Rest/binary>>, + LocalVersion, _LegacyVersion) when Len =:= 2 -> + SelectedVersion = {Major, Minor}, + if SelectedVersion =< LocalVersion -> + SelectedVersion; + true -> + LocalVersion + end; +process_supported_versions_extension(<<?UINT16(_), ?UINT16(Len), + _ExtData:Len/binary, Rest/binary>>, + LocalVersion, LegacyVersion) -> + process_supported_versions_extension(Rest, LocalVersion, LegacyVersion); +%% Tolerate protocol encoding errors and skip parsing the rest of the extension. +process_supported_versions_extension(_, LocalVersion, LegacyVersion) + when LegacyVersion =< LocalVersion -> + LegacyVersion; +process_supported_versions_extension(_, LocalVersion, _) -> + LocalVersion. + decode_extensions(<<>>, _Version, _MessageType, Acc) -> Acc; decode_extensions(<<?UINT16(?ALPN_EXT), ?UINT16(ExtLen), ?UINT16(Len), |