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Add size limit to server Message Codec #205

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Add size limit to server Message Codec #205

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16 changes: 16 additions & 0 deletions websocket-codec/src/message.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,7 @@ impl Message {
#[derive(Clone)]
pub struct MessageCodec {
interrupted_message: Option<(Opcode, BytesMut)>,
size_limit: Option<usize>,
use_mask: bool,
}

Expand All @@ -154,6 +155,16 @@ impl MessageCodec {
Self {
use_mask,
interrupted_message: None,
size_limit: None,
}
}

/// Create a `MessageCodec` for a server, with a specified size limit to prevent DoS attacks
pub fn server_with_message_size_limit(limit: usize) -> Self {
Self {
use_mask: false,
interrupted_message: None,
size_limit: Some(limit),
}
}
}
Expand Down Expand Up @@ -188,6 +199,8 @@ impl Decoder for MessageCodec {
// max payload length detailed in the RFC of 2^63 bytes.
if frame_len > usize::MAX - src.remaining() {
return Err(format!("frame is too long: {0} bytes ({0:x})", frame_len).into());
}else if frame_len > self.size_limit.unwrap_or(usize::MAX) {
return Err(format!("frame exceeds size limit: {0} bytes ({0:x})", frame_len).into());
}

// We don't really reserve space for the entire frame data in a single call. If somebody is sending
Expand Down Expand Up @@ -245,6 +258,9 @@ impl Decoder for MessageCodec {

return Err(format!("continuation frame must have continuation opcode, not {:?}", opcode).into());
} else {
if partial_data.len() + data.len() > self.size_limit.unwrap_or(usize::MAX) {
return Err(format!("Message exceeds size limit: {0} bytes ({0:x})", partial_data.len() + data.len()).into());
}
partial_data.extend_from_slice(&data);

if fin {
Expand Down