nquic_conn (nquic v1.0.0)

QUIC Connection Management API.

This module provides functions to query connection state, statistics, and to close connections. Use nquic for establishing connections and stream operations.

Connection Information

The info/1 function returns a map containing:

state - Connection state (initial, handshake, established)
role - client or server
scid - Source connection ID
dcid - Destination connection ID
rtt - RTT statistics (smoothed, variance, min, latest)
cwnd - Congestion window size in bytes
bytes_in_flight - Unacknowledged bytes
streams_open - Number of active streams

Summary

Functions

close(Conn)

Close the connection gracefully with no error.

close(Conn, ErrorCode, ReasonPhrase)

Close the connection with an error code and reason. Sends a CONNECTION_CLOSE frame with the specified error code and reason phrase, then terminates the connection. Common error codes (RFC 9000 Section 20)

info(Conn)

Get connection information and statistics. Returns detailed information about the connection including RTT measurements, congestion control state, and transport parameters.

migrate(Conn, NewLocalAddr)

Migrate the connection to a new local address (RFC 9000 Section 9). Initiates active connection migration by rebinding the client socket to the new local address and sending a PATH_CHALLENGE to validate the new path. Returns {error, migration_disabled} if the peer set disable_active_migration. Only works in the established state.

path_stats(Conn)

Get path-level statistics for the connection. Returns a flat map suitable for routing decisions (srtt_us, cwnd, bytes_in_flight, ssthresh, ...) and for operational dashboards (lifetime packets_sent, packets_lost, packets_acked, ECN counters, pto_count). Reads cached state inside the gen_statem; no protocol I/O.

peercert(Conn)

Get the peer's TLS certificate in DER format.

peername(Conn)

Get the peer's address and port.

sockname(Conn)

Get the local address and port.

streams(Conn)

List active stream IDs on the connection.

Types

conn_info()

-type conn_info() ::
          #{state := atom(),
            role := client | server,
            scid := nquic:connection_id(),
            dcid := nquic:connection_id(),
            rtt :=
                #{smoothed := non_neg_integer(),
                  variance := non_neg_integer(),
                  min := non_neg_integer(),
                  latest := non_neg_integer()},
            cwnd := non_neg_integer(),
            bytes_in_flight := non_neg_integer(),
            streams_open := non_neg_integer(),
            local_params :=
                #transport_params{original_destination_connection_id ::
                                      nquic:connection_id() | undefined,
                                  max_idle_timeout :: non_neg_integer(),
                                  stateless_reset_token :: binary() | undefined,
                                  max_udp_payload_size :: pos_integer(),
                                  initial_max_data :: non_neg_integer(),
                                  initial_max_stream_data_bidi_local :: non_neg_integer(),
                                  initial_max_stream_data_bidi_remote :: non_neg_integer(),
                                  initial_max_stream_data_uni :: non_neg_integer(),
                                  initial_max_streams_bidi :: non_neg_integer(),
                                  initial_max_streams_uni :: non_neg_integer(),
                                  ack_delay_exponent :: 0..20,
                                  max_ack_delay :: non_neg_integer(),
                                  disable_active_migration :: boolean(),
                                  preferred_address :: nquic_transport:preferred_address() | undefined,
                                  active_connection_id_limit :: non_neg_integer(),
                                  initial_source_connection_id :: nquic:connection_id() | undefined,
                                  retry_source_connection_id :: nquic:connection_id() | undefined,
                                  version_information ::
                                      nquic_transport:version_information() | undefined,
                                  max_datagram_frame_size :: non_neg_integer() | undefined},
            remote_params :=
                #transport_params{original_destination_connection_id ::
                                      nquic:connection_id() | undefined,
                                  max_idle_timeout :: non_neg_integer(),
                                  stateless_reset_token :: binary() | undefined,
                                  max_udp_payload_size :: pos_integer(),
                                  initial_max_data :: non_neg_integer(),
                                  initial_max_stream_data_bidi_local :: non_neg_integer(),
                                  initial_max_stream_data_bidi_remote :: non_neg_integer(),
                                  initial_max_stream_data_uni :: non_neg_integer(),
                                  initial_max_streams_bidi :: non_neg_integer(),
                                  initial_max_streams_uni :: non_neg_integer(),
                                  ack_delay_exponent :: 0..20,
                                  max_ack_delay :: non_neg_integer(),
                                  disable_active_migration :: boolean(),
                                  preferred_address :: nquic_transport:preferred_address() | undefined,
                                  active_connection_id_limit :: non_neg_integer(),
                                  initial_source_connection_id :: nquic:connection_id() | undefined,
                                  retry_source_connection_id :: nquic:connection_id() | undefined,
                                  version_information ::
                                      nquic_transport:version_information() | undefined,
                                  max_datagram_frame_size :: non_neg_integer() | undefined} |
                undefined}.