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-rw-r--r--src/message.cpp253
-rw-r--r--src/ratchet.cpp9
2 files changed, 203 insertions, 59 deletions
diff --git a/src/message.cpp b/src/message.cpp
index 46cadd8..fcedd07 100644
--- a/src/message.cpp
+++ b/src/message.cpp
@@ -81,6 +81,82 @@ static std::uint8_t const RATCHET_KEY_TAG = 012;
static std::uint8_t const COUNTER_TAG = 020;
static std::uint8_t const CIPHERTEXT_TAG = 042;
+std::uint8_t * encode(
+ std::uint8_t * pos,
+ std::uint8_t tag,
+ std::uint32_t value
+) {
+ *(pos++) = tag;
+ return varint_encode(pos, value);
+}
+
+std::uint8_t * encode(
+ std::uint8_t * pos,
+ std::uint8_t tag,
+ std::uint8_t * & value, std::size_t value_length
+) {
+ *(pos++) = tag;
+ pos = varint_encode(pos, value_length);
+ value = pos;
+ return pos + value_length;
+}
+
+std::uint8_t const * decode(
+ std::uint8_t const * pos, std::uint8_t const * end,
+ std::uint8_t tag,
+ std::uint32_t & value, bool & has_value
+) {
+ if (pos != end && *pos == tag) {
+ ++pos;
+ std::uint8_t const * value_start = pos;
+ pos = varint_skip(pos, end);
+ value = varint_decode<std::uint32_t>(value_start, pos);
+ has_value = true;
+ }
+ return pos;
+}
+
+
+std::uint8_t const * decode(
+ std::uint8_t const * pos, std::uint8_t const * end,
+ std::uint8_t tag,
+ std::uint8_t const * & value, std::size_t & value_length
+) {
+ if (pos != end && *pos == tag) {
+ ++pos;
+ std::uint8_t const * len_start = pos;
+ pos = varint_skip(pos, end);
+ std::size_t len = varint_decode<std::size_t>(len_start, pos);
+ if (len > end - pos) return end;
+ value = pos;
+ value_length = len;
+ pos += len;
+ }
+ return pos;
+}
+
+std::uint8_t const * skip_unknown(
+ std::uint8_t const * pos, std::uint8_t const * end
+) {
+ if (pos != end) {
+ uint8_t tag = *pos;
+ if (tag & 0x7 == 0) {
+ pos = varint_skip(pos, end);
+ pos = varint_skip(pos, end);
+ } else if (tag & 0x7 == 2) {
+ pos = varint_skip(pos, end);
+ std::uint8_t const * len_start = pos;
+ pos = varint_skip(pos, end);
+ std::size_t len = varint_decode<std::size_t>(len_start, pos);
+ if (len > end - pos) return end;
+ pos += len;
+ } else {
+ return end;
+ }
+ }
+ return pos;
+}
+
} // namespace
@@ -109,75 +185,138 @@ void axolotl::encode_message(
) {
std::uint8_t * pos = output;
*(pos++) = version;
- *(pos++) = COUNTER_TAG;
- pos = varint_encode(pos, counter);
- *(pos++) = RATCHET_KEY_TAG;
- pos = varint_encode(pos, ratchet_key_length);
- writer.ratchet_key = pos;
- pos += ratchet_key_length;
- *(pos++) = CIPHERTEXT_TAG;
- pos = varint_encode(pos, ciphertext_length);
- writer.ciphertext = pos;
- pos += ciphertext_length;
+ pos = encode(pos, RATCHET_KEY_TAG, writer.ratchet_key, ratchet_key_length);
+ pos = encode(pos, COUNTER_TAG, counter);
+ pos = encode(pos, CIPHERTEXT_TAG, writer.ciphertext, ciphertext_length);
}
-std::size_t axolotl::decode_message(
+void axolotl::decode_message(
axolotl::MessageReader & reader,
std::uint8_t const * input, std::size_t input_length,
std::size_t mac_length
) {
std::uint8_t const * pos = input;
std::uint8_t const * end = input + input_length - mac_length;
- std::uint8_t flags = 0;
- std::size_t result = std::size_t(-1);
- if (pos == end) return result;
+ std::uint8_t const * unknown = NULL;
+
+ if (pos == end) return;
reader.version = *(pos++);
+ reader.input = input;
+ reader.input_length = input_length;
+ reader.has_counter = false;
+ reader.ratchet_key = NULL;
+ reader.ciphertext = NULL;
+
while (pos != end) {
- uint8_t tag = *(pos);
- if (tag == COUNTER_TAG) {
- ++pos;
- std::uint8_t const * counter_start = pos;
- pos = varint_skip(pos, end);
- reader.counter = varint_decode<std::uint32_t>(counter_start, pos);
- flags |= 1;
- } else if (tag == RATCHET_KEY_TAG) {
- ++pos;
- std::uint8_t const * len_start = pos;
- pos = varint_skip(pos, end);
- std::size_t len = varint_decode<std::size_t>(len_start, pos);
- if (len > end - pos) return result;
- reader.ratchet_key_length = len;
- reader.ratchet_key = pos;
- pos += len;
- flags |= 2;
- } else if (tag == CIPHERTEXT_TAG) {
- ++pos;
- std::uint8_t const * len_start = pos;
- pos = varint_skip(pos, end);
- std::size_t len = varint_decode<std::size_t>(len_start, pos);
- if (len > end - pos) return result;
- reader.ciphertext_length = len;
- reader.ciphertext = pos;
- pos += len;
- flags |= 4;
- } else if (tag & 0x7 == 0) {
- pos = varint_skip(pos, end);
- pos = varint_skip(pos, end);
- } else if (tag & 0x7 == 2) {
- std::uint8_t const * len_start = pos;
- pos = varint_skip(pos, end);
- std::size_t len = varint_decode<std::size_t>(len_start, pos);
- if (len > end - pos) return result;
- pos += len;
- } else {
- return std::size_t(-1);
+ pos = decode(
+ pos, end, RATCHET_KEY_TAG,
+ reader.ratchet_key, reader.ratchet_key_length
+ );
+ pos = decode(
+ pos, end, COUNTER_TAG,
+ reader.counter, reader.has_counter
+ );
+ pos = decode(
+ pos, end, CIPHERTEXT_TAG,
+ reader.ciphertext, reader.ciphertext_length
+ );
+ if (unknown == pos) {
+ pos == skip_unknown(pos, end);
}
+ unknown = pos;
}
- if (flags == 0x7) {
- reader.input = input;
- reader.input_length = input_length;
- return std::size_t(pos - input);
+}
+
+
+namespace {
+
+static std::uint8_t const REGISTRATION_ID_TAG = 050;
+static std::uint8_t const ONE_TIME_KEY_ID_TAG = 010;
+static std::uint8_t const BASE_KEY_TAG = 022;
+static std::uint8_t const IDENTITY_KEY_TAG = 032;
+static std::uint8_t const MESSAGE_TAG = 042;
+
+} // namespace
+
+
+std::size_t axolotl::encode_one_time_key_message_length(
+ std::uint32_t registration_id,
+ std::uint32_t one_time_key_id,
+ std::size_t identity_key_length,
+ std::size_t base_key_length,
+ std::size_t message_length
+) {
+ std::size_t length = VERSION_LENGTH;
+ length += 1 + varint_length(registration_id);
+ length += 1 + varint_length(one_time_key_id);
+ length += 1 + varstring_length(identity_key_length);
+ length += 1 + varstring_length(base_key_length);
+ length += 1 + varstring_length(message_length);
+ return length;
+}
+
+
+void axolotl::encode_one_time_key_message(
+ axolotl::PreKeyMessageWriter & writer,
+ std::uint8_t version,
+ std::uint32_t registration_id,
+ std::uint32_t one_time_key_id,
+ std::size_t identity_key_length,
+ std::size_t base_key_length,
+ std::size_t message_length,
+ std::uint8_t * output
+) {
+ std::uint8_t * pos = output;
+ *(pos++) = version;
+ pos = encode(pos, REGISTRATION_ID_TAG, registration_id);
+ pos = encode(pos, ONE_TIME_KEY_ID_TAG, one_time_key_id);
+ pos = encode(pos, BASE_KEY_TAG, writer.base_key, base_key_length);
+ pos = encode(pos, IDENTITY_KEY_TAG, writer.identity_key, identity_key_length);
+ pos = encode(pos, MESSAGE_TAG, writer.message, message_length);
+}
+
+
+void axolotl::decode_one_time_key_message(
+ PreKeyMessageReader & reader,
+ std::uint8_t const * input, std::size_t input_length
+) {
+ std::uint8_t const * pos = input;
+ std::uint8_t const * end = input + input_length;
+ std::uint8_t const * unknown = NULL;
+
+ if (pos == end) return;
+ reader.version = *(pos++);
+ reader.has_registration_id = false;
+ reader.has_one_time_key_id = false;
+ reader.identity_key = NULL;
+ reader.base_key = NULL;
+ reader.message = NULL;
+
+ while (pos != end) {
+ pos = decode(
+ pos, end, REGISTRATION_ID_TAG,
+ reader.registration_id, reader.has_registration_id
+ );
+ pos = decode(
+ pos, end, ONE_TIME_KEY_ID_TAG,
+ reader.one_time_key_id, reader.has_one_time_key_id
+ );
+ pos = decode(
+ pos, end, BASE_KEY_TAG,
+ reader.base_key, reader.base_key_length
+ );
+ pos = decode(
+ pos, end, IDENTITY_KEY_TAG,
+ reader.identity_key, reader.identity_key_length
+ );
+ pos = decode(
+ pos, end, MESSAGE_TAG,
+ reader.message, reader.message_length
+ );
+ if (unknown == pos) {
+ pos == skip_unknown(pos, end);
+ }
+ unknown = pos;
}
- return result;
}
diff --git a/src/ratchet.cpp b/src/ratchet.cpp
index cd4f8f7..cbafa83 100644
--- a/src/ratchet.cpp
+++ b/src/ratchet.cpp
@@ -444,7 +444,7 @@ std::size_t axolotl::Session::decrypt(
}
axolotl::MessageReader reader;
- std::size_t body_length = axolotl::decode_message(
+ axolotl::decode_message(
reader, input, input_length, ratchet_cipher.mac_length()
);
@@ -453,7 +453,12 @@ std::size_t axolotl::Session::decrypt(
return std::size_t(-1);
}
- if (body_length == size_t(-1) || reader.ratchet_key_length != KEY_LENGTH) {
+ if (!reader.has_counter || !reader.ratchet_key || !reader.ciphertext) {
+ last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+
+ if (reader.ratchet_key_length != KEY_LENGTH) {
last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
return std::size_t(-1);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-25 18:35:33 +0000