Module framing 

HTTP/2 gRPC frame parsing for client streaming support

This module provides parsing of gRPC messages from HTTP/2 request bodies. gRPC frames are structured according to RFC 9109 (gRPC over HTTP/2):

+----------+----------+-+-+-+-+-+-+-+-+
|Compression|          Length        |
| Flags (1) |        (4 bytes)       |
+----------+----------+-+-+-+-+-+-+-+-+-+-+
|                                     |
|      Serialized Message (N bytes)  |
|                                     |
+-------------------------------------+

The compression flag indicates whether the message is compressed (1 = compressed, 0 = uncompressed). The length is encoded as a big-endian u32, indicating the size of the message bytes.

Protocol Details

• Compression Flag: 1 byte, value 0 or 1
• Message Length: 4 bytes, big-endian u32, maximum 4GB
• Message Data: N bytes, where N is the length from the header

Stream Processing

The parser processes the HTTP/2 body stream by:

1. Reading the 5-byte frame header (compression flag + length)
2. Parsing the length as big-endian u32
3. Validating the length against max_message_size
4. Reading the message bytes
5. Yielding the message
6. Repeating until the body is exhausted

Error Handling

The parser returns gRPC status codes according to RFC 9110:

• INTERNAL: Protocol parsing errors (incomplete frames, read errors)
• RESOURCE_EXHAUSTED: Message size exceeds limit
• UNIMPLEMENTED: Compression requested (not supported)

Example

use spikard_http::grpc::framing::parse_grpc_client_stream;
use axum::body::Body;
use bytes::Bytes;
use futures_util::StreamExt;

let body = Body::from("...");
let max_size = 4 * 1024 * 1024; // 4MB
let mut stream = parse_grpc_client_stream(body, max_size).await?;

while let Some(result) = stream.next().await {
    match result {
        Ok(message) => println!("Message: {:?}", message),
        Err(status) => eprintln!("Error: {}", status),
    }
}

Functions

parse_grpc_client_stream

Parses an HTTP/2 gRPC request body as a stream of messages