switch (state_) {

case kWaiting:

if (!ParseRecordHeader(data, avail))

break;

// Fall through

case kTLSHeader:

ParseHeader(data, avail);

break;

case kPaused:

// Just nop

case kEnded:

// Already ended, just ignore it

break;

default:

break;

}

// >= 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;

ClientHello hello;

// >= 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

//

if (data[body_offset_ + 4] != 0x03 ||

data[body_offset_ + 5] < 0x01 ||

data[body_offset_ + 5] > 0x03) {

goto fail;

}

if (data[body_offset_] == kClientHello) {

if (state_ == kTLSHeader) {

if (!ParseTLSClientHello(data, avail))

goto fail;

} else {

// We couldn't get here, but whatever

goto fail;

}

// Check if we overflowed (do not reply with any private data)

if (session_id_ == nullptr ||

session_size_ > 32 ||

session_id_ + session_size_ > data + avail) {

goto fail;

}

}

state_ = kPaused;

hello.session_id_ = session_id_;

hello.session_size_ = session_size_;

hello.has_ticket_ = tls_ticket_ != nullptr && tls_ticket_size_ != 0;

hello.ocsp_request_ = ocsp_request_;

hello.servername_ = servername_;

hello.servername_size_ = static_cast<uint8_t>(servername_size_);

onhello_cb_(cb_arg_, hello);

return;

fail:

End();

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 kStatusRequest:

// We are ignoring any data, just indicating the presence of extension

if (len < kMinStatusRequestSize)

return;

// Unknown type, ignore it

if (data[0] != kStatusRequestOCSP)

break;

// Ignore extensions, they won't work with caching on backend anyway

ocsp_request_ = 1;

break;

case kTLSSessionTicket:

tls_ticket_size_ = len;

tls_ticket_ = data + len;

break;

default:

// Ignore

break;

}

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;