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crypto_clienthello.cc
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// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
#include "crypto/crypto_clienthello.h" // NOLINT(build/include_inline)
#include "crypto/crypto_clienthello-inl.h"
namespace node {
namespace crypto {
void ClientHelloParser::Parse(const uint8_t* data, size_t avail) {
switch (state_) {
case kWaiting:
if (!ParseRecordHeader(data, avail))
break;
[[fallthrough]];
case kTLSHeader:
ParseHeader(data, avail);
break;
case kPaused:
// Just nop
case kEnded:
// Already ended, just ignore it
break;
default:
break;
}
}
bool ClientHelloParser::ParseRecordHeader(const uint8_t* data, size_t avail) {
// >= 5 bytes for header parsing
if (avail < 5)
return false;
if (data[0] == kChangeCipherSpec ||
data[0] == kAlert ||
data[0] == kHandshake ||
data[0] == kApplicationData) {
frame_len_ = (data[3] << 8) + data[4];
state_ = kTLSHeader;
body_offset_ = 5;
} else {
End();
return false;
}
// Sanity check (too big frame, or too small)
// Let OpenSSL handle it
if (frame_len_ >= kMaxTLSFrameLen) {
End();
return false;
}
return true;
}
void ClientHelloParser::ParseHeader(const uint8_t* data, size_t avail) {
ClientHello hello;
// We need at least six bytes (one byte for kClientHello, three bytes for the
// length of the handshake message, and two bytes for the protocol version).
// If the client sent a frame that suggests a smaller ClientHello, give up.
if (frame_len_ < 6) return End();
// >= 5 + frame size bytes for frame parsing
if (body_offset_ + frame_len_ > avail)
return;
// Check hello protocol version. Protocol tuples that we know about:
//
// (3,1) TLS v1.0
// (3,2) TLS v1.1
// (3,3) TLS v1.2
//
// Note that TLS v1.3 uses a TLS v1.2 handshake so requires no specific
// support here.
if (data[body_offset_ + 4] != 0x03 ||
data[body_offset_ + 5] < 0x01 ||
data[body_offset_ + 5] > 0x03) {
return End();
}
if (data[body_offset_] == kClientHello) {
if (state_ == kTLSHeader) {
if (!ParseTLSClientHello(data, avail))
return End();
} else {
// We couldn't get here, but whatever
return End();
}
// Check if we overflowed (do not reply with any private data)
if (session_id_ == nullptr ||
session_size_ > 32 ||
session_id_ + session_size_ > data + avail) {
return End();
}
}
state_ = kPaused;
hello.session_id_ = session_id_;
hello.session_size_ = session_size_;
hello.has_ticket_ = tls_ticket_ != nullptr && tls_ticket_size_ != 0;
hello.servername_ = servername_;
hello.servername_size_ = static_cast<uint8_t>(servername_size_);
onhello_cb_(cb_arg_, hello);
}
void ClientHelloParser::ParseExtension(const uint16_t type,
const uint8_t* data,
size_t len) {
// NOTE: In case of anything we're just returning back, ignoring the problem.
// That's because we're heavily relying on OpenSSL to solve any problem with
// incoming data.
switch (type) {
case kServerName:
{
if (len < 2)
return;
uint32_t server_names_len = (data[0] << 8) + data[1];
if (server_names_len + 2 > len)
return;
for (size_t offset = 2; offset < 2 + server_names_len; ) {
if (offset + 3 > len)
return;
uint8_t name_type = data[offset];
if (name_type != kServernameHostname)
return;
uint16_t name_len = (data[offset + 1] << 8) + data[offset + 2];
offset += 3;
if (offset + name_len > len)
return;
servername_ = data + offset;
servername_size_ = name_len;
offset += name_len;
}
}
break;
case kTLSSessionTicket:
tls_ticket_size_ = len;
tls_ticket_ = data + len;
break;
default:
// Ignore
break;
}
}
bool ClientHelloParser::ParseTLSClientHello(const uint8_t* data, size_t avail) {
const uint8_t* body;
// Skip frame header, hello header, protocol version and random data
size_t session_offset = body_offset_ + 4 + 2 + 32;
if (session_offset + 1 >= avail)
return false;
body = data + session_offset;
session_size_ = *body;
session_id_ = body + 1;
size_t cipher_offset = session_offset + 1 + session_size_;
// Session OOB failure
if (cipher_offset + 1 >= avail)
return false;
uint16_t cipher_len =
(data[cipher_offset] << 8) + data[cipher_offset + 1];
size_t comp_offset = cipher_offset + 2 + cipher_len;
// Cipher OOB failure
if (comp_offset >= avail)
return false;
uint8_t comp_len = data[comp_offset];
size_t extension_offset = comp_offset + 1 + comp_len;
// Compression OOB failure
if (extension_offset > avail)
return false;
// No extensions present
if (extension_offset == avail)
return true;
size_t ext_off = extension_offset + 2;
// Parse known extensions
while (ext_off < avail) {
// Extension OOB
if (ext_off + 4 > avail)
return false;
uint16_t ext_type = (data[ext_off] << 8) + data[ext_off + 1];
uint16_t ext_len = (data[ext_off + 2] << 8) + data[ext_off + 3];
ext_off += 4;
// Extension OOB
if (ext_off + ext_len > avail)
return false;
ParseExtension(ext_type,
data + ext_off,
ext_len);
ext_off += ext_len;
}
// Extensions OOB failure
if (ext_off > avail)
return false;
return true;
}
} // namespace crypto
} // namespace node