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ntlm_buffer_reader.cc
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ntlm_buffer_reader.cc
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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/ntlm/ntlm_buffer_reader.h"
#include <string.h>
#include "base/logging.h"
namespace net {
namespace ntlm {
NtlmBufferReader::NtlmBufferReader() : NtlmBufferReader(nullptr, 0) {}
NtlmBufferReader::NtlmBufferReader(const Buffer& buffer)
: NtlmBufferReader(
base::StringPiece(reinterpret_cast<const char*>(buffer.data()),
buffer.length())) {}
NtlmBufferReader::NtlmBufferReader(base::StringPiece str)
: buffer_(str), cursor_(0) {}
NtlmBufferReader::NtlmBufferReader(const uint8_t* ptr, size_t len)
: NtlmBufferReader(
base::StringPiece(reinterpret_cast<const char*>(ptr), len)) {}
NtlmBufferReader::~NtlmBufferReader() = default;
bool NtlmBufferReader::CanRead(size_t len) const {
return CanReadFrom(GetCursor(), len);
}
bool NtlmBufferReader::CanReadFrom(size_t offset, size_t len) const {
if (len == 0)
return true;
return (len <= GetLength() && offset <= GetLength() - len);
}
bool NtlmBufferReader::ReadUInt16(uint16_t* value) {
return ReadUInt<uint16_t>(value);
}
bool NtlmBufferReader::ReadUInt32(uint32_t* value) {
return ReadUInt<uint32_t>(value);
}
bool NtlmBufferReader::ReadUInt64(uint64_t* value) {
return ReadUInt<uint64_t>(value);
}
bool NtlmBufferReader::ReadFlags(NegotiateFlags* flags) {
uint32_t raw;
if (!ReadUInt32(&raw))
return false;
*flags = static_cast<NegotiateFlags>(raw);
return true;
}
bool NtlmBufferReader::ReadBytes(uint8_t* buffer, size_t len) {
if (!CanRead(len))
return false;
memcpy(reinterpret_cast<void*>(buffer),
reinterpret_cast<const void*>(GetBufferAtCursor()), len);
AdvanceCursor(len);
return true;
}
bool NtlmBufferReader::ReadBytesFrom(const SecurityBuffer& sec_buf,
uint8_t* buffer) {
if (!CanReadFrom(sec_buf))
return false;
memcpy(reinterpret_cast<void*>(buffer),
reinterpret_cast<const void*>(GetBufferPtr() + sec_buf.offset),
sec_buf.length);
return true;
}
bool NtlmBufferReader::ReadPayloadAsBufferReader(const SecurityBuffer& sec_buf,
NtlmBufferReader* reader) {
if (!CanReadFrom(sec_buf))
return false;
*reader = NtlmBufferReader(GetBufferPtr() + sec_buf.offset, sec_buf.length);
return true;
}
bool NtlmBufferReader::ReadSecurityBuffer(SecurityBuffer* sec_buf) {
return ReadUInt16(&sec_buf->length) && SkipBytes(sizeof(uint16_t)) &&
ReadUInt32(&sec_buf->offset);
}
bool NtlmBufferReader::ReadAvPairHeader(TargetInfoAvId* avid, uint16_t* avlen) {
if (!CanRead(kAvPairHeaderLen))
return false;
uint16_t raw_avid;
bool result = ReadUInt16(&raw_avid) && ReadUInt16(avlen);
DCHECK(result);
// Don't try and validate the avid because the code only cares about a few
// specific ones and it is likely a future version might extend this field.
// The implementation can ignore and skip over AV Pairs it doesn't
// understand.
*avid = static_cast<TargetInfoAvId>(raw_avid);
return true;
}
bool NtlmBufferReader::ReadTargetInfo(size_t target_info_len,
std::vector<AvPair>* av_pairs) {
DCHECK(av_pairs->empty());
// A completely empty target info is allowed.
if (target_info_len == 0)
return true;
// If there is any content there has to be at least one terminating header.
if (!CanRead(target_info_len) || target_info_len < kAvPairHeaderLen) {
return false;
}
size_t target_info_end = GetCursor() + target_info_len;
bool saw_eol = false;
while ((GetCursor() < target_info_end)) {
AvPair pair;
if (!ReadAvPairHeader(&pair.avid, &pair.avlen))
break;
// Make sure the length wouldn't read outside the buffer.
if (!CanRead(pair.avlen))
return false;
// Take a copy of the payload in the AVPair.
pair.buffer.assign(GetBufferAtCursor(), pair.avlen);
if (pair.avid == TargetInfoAvId::kEol) {
// Terminator must have zero length.
if (pair.avlen != 0)
return false;
// Break out of the loop once a valid terminator is found. After the
// loop it will be validated that the whole target info was consumed.
saw_eol = true;
break;
}
switch (pair.avid) {
case TargetInfoAvId::kFlags:
// For flags also populate the flags field so it doesn't
// have to be modified through the raw buffer later.
if (pair.avlen != sizeof(uint32_t) ||
!ReadUInt32(reinterpret_cast<uint32_t*>(&pair.flags)))
return false;
break;
case TargetInfoAvId::kTimestamp:
// Populate timestamp so it doesn't need to be read through the
// raw buffer later.
if (pair.avlen != sizeof(uint64_t) || !ReadUInt64(&pair.timestamp))
return false;
break;
case TargetInfoAvId::kChannelBindings:
case TargetInfoAvId::kTargetName:
// The server should never send these, and with EPA enabled the client
// will add these to the authenticate message. To avoid issues with
// duplicates or only one being read, just don't allow them.
return false;
default:
// For all other types, just jump over the payload to the next pair.
// If there aren't enough bytes left, then fail.
if (!SkipBytes(pair.avlen))
return false;
break;
}
av_pairs->push_back(std::move(pair));
}
// Fail if the buffer wasn't properly formed. The entire payload should have
// been consumed and a terminator found.
if ((GetCursor() != target_info_end) || !saw_eol)
return false;
return true;
}
bool NtlmBufferReader::ReadTargetInfoPayload(std::vector<AvPair>* av_pairs) {
DCHECK(av_pairs->empty());
SecurityBuffer sec_buf;
// First read the security buffer.
if (!ReadSecurityBuffer(&sec_buf))
return false;
NtlmBufferReader payload_reader;
if (!ReadPayloadAsBufferReader(sec_buf, &payload_reader))
return false;
if (!payload_reader.ReadTargetInfo(sec_buf.length, av_pairs))
return false;
// |ReadTargetInfo| should have consumed the entire contents.
return payload_reader.IsEndOfBuffer();
}
bool NtlmBufferReader::ReadMessageType(MessageType* message_type) {
uint32_t raw_message_type;
if (!ReadUInt32(&raw_message_type))
return false;
*message_type = static_cast<MessageType>(raw_message_type);
if (*message_type != MessageType::kNegotiate &&
*message_type != MessageType::kChallenge &&
*message_type != MessageType::kAuthenticate)
return false;
return true;
}
bool NtlmBufferReader::SkipSecurityBuffer() {
return SkipBytes(kSecurityBufferLen);
}
bool NtlmBufferReader::SkipSecurityBufferWithValidation() {
SecurityBuffer sec_buf;
return ReadSecurityBuffer(&sec_buf) && CanReadFrom(sec_buf);
}
bool NtlmBufferReader::SkipBytes(size_t count) {
if (!CanRead(count))
return false;
AdvanceCursor(count);
return true;
}
bool NtlmBufferReader::MatchSignature() {
if (!CanRead(kSignatureLen))
return false;
if (memcmp(kSignature, GetBufferAtCursor(), kSignatureLen) != 0)
return false;
AdvanceCursor(kSignatureLen);
return true;
}
bool NtlmBufferReader::MatchMessageType(MessageType message_type) {
MessageType actual_message_type;
return ReadMessageType(&actual_message_type) &&
(actual_message_type == message_type);
}
bool NtlmBufferReader::MatchMessageHeader(MessageType message_type) {
return MatchSignature() && MatchMessageType(message_type);
}
bool NtlmBufferReader::MatchZeros(size_t count) {
if (!CanRead(count))
return false;
for (size_t i = 0; i < count; i++) {
if (GetBufferAtCursor()[i] != 0)
return false;
}
AdvanceCursor(count);
return true;
}
bool NtlmBufferReader::MatchEmptySecurityBuffer() {
SecurityBuffer sec_buf;
return ReadSecurityBuffer(&sec_buf) && (sec_buf.offset <= GetLength()) &&
(sec_buf.length == 0);
}
template <typename T>
bool NtlmBufferReader::ReadUInt(T* value) {
size_t int_size = sizeof(T);
if (!CanRead(int_size))
return false;
*value = 0;
for (size_t i = 0; i < int_size; i++) {
*value += static_cast<T>(GetByteAtCursor()) << (i * 8);
AdvanceCursor(1);
}
return true;
}
void NtlmBufferReader::SetCursor(size_t cursor) {
DCHECK_LE(cursor, GetLength());
cursor_ = cursor;
}
} // namespace ntlm
} // namespace net