target = "https://www.rfc-editor.org/rfc/rfc9000#section-18.2"

# 18.2.  Transport Parameter Definitions
#
# This section details the transport parameters defined in this
# document.
# 
# Many transport parameters listed here have integer values.  Those
# transport parameters that are identified as integers use a variable-
# length integer encoding; see Section 16.  Transport parameters have a
# default value of 0 if the transport parameter is absent, unless
# otherwise stated.
# 
# The following transport parameters are defined:
# 
# original_destination_connection_id (0x00):  This parameter is the
#    value of the Destination Connection ID field from the first
#    Initial packet sent by the client; see Section 7.3.  This
#    transport parameter is only sent by a server.
# 
# max_idle_timeout (0x01):  The maximum idle timeout is a value in
#    milliseconds that is encoded as an integer; see (Section 10.1).
#    Idle timeout is disabled when both endpoints omit this transport
#    parameter or specify a value of 0.
# 
# stateless_reset_token (0x02):  A stateless reset token is used in
#    verifying a stateless reset; see Section 10.3.  This parameter is
#    a sequence of 16 bytes.  This transport parameter MUST NOT be sent
#    by a client but MAY be sent by a server.  A server that does not
#    send this transport parameter cannot use stateless reset
#    (Section 10.3) for the connection ID negotiated during the
#    handshake.
# 
# max_udp_payload_size (0x03):  The maximum UDP payload size parameter
#    is an integer value that limits the size of UDP payloads that the
#    endpoint is willing to receive.  UDP datagrams with payloads
#    larger than this limit are not likely to be processed by the
#    receiver.
# 
#    The default for this parameter is the maximum permitted UDP
#    payload of 65527.  Values below 1200 are invalid.
# 
#    This limit does act as an additional constraint on datagram size
#    in the same way as the path MTU, but it is a property of the
#    endpoint and not the path; see Section 14.  It is expected that
#    this is the space an endpoint dedicates to holding incoming
#    packets.
# 
# initial_max_data (0x04):  The initial maximum data parameter is an
#    integer value that contains the initial value for the maximum
#    amount of data that can be sent on the connection.  This is
#    equivalent to sending a MAX_DATA (Section 19.9) for the connection
#    immediately after completing the handshake.
# 
# initial_max_stream_data_bidi_local (0x05):  This parameter is an
#    integer value specifying the initial flow control limit for
#    locally initiated bidirectional streams.  This limit applies to
#    newly created bidirectional streams opened by the endpoint that
#    sends the transport parameter.  In client transport parameters,
#    this applies to streams with an identifier with the least
#    significant two bits set to 0x00; in server transport parameters,
#    this applies to streams with the least significant two bits set to
#    0x01.
# 
# initial_max_stream_data_bidi_remote (0x06):  This parameter is an
#    integer value specifying the initial flow control limit for peer-
#    initiated bidirectional streams.  This limit applies to newly
#    created bidirectional streams opened by the endpoint that receives
#    the transport parameter.  In client transport parameters, this
#    applies to streams with an identifier with the least significant
#    two bits set to 0x01; in server transport parameters, this applies
#    to streams with the least significant two bits set to 0x00.
# 
# initial_max_stream_data_uni (0x07):  This parameter is an integer
#    value specifying the initial flow control limit for unidirectional
#    streams.  This limit applies to newly created unidirectional
#    streams opened by the endpoint that receives the transport
#    parameter.  In client transport parameters, this applies to
#    streams with an identifier with the least significant two bits set
#    to 0x03; in server transport parameters, this applies to streams
#    with the least significant two bits set to 0x02.
# 
# initial_max_streams_bidi (0x08):  The initial maximum bidirectional
#    streams parameter is an integer value that contains the initial
#    maximum number of bidirectional streams the endpoint that receives
#    this transport parameter is permitted to initiate.  If this
#    parameter is absent or zero, the peer cannot open bidirectional
#    streams until a MAX_STREAMS frame is sent.  Setting this parameter
#    is equivalent to sending a MAX_STREAMS (Section 19.11) of the
#    corresponding type with the same value.
# 
# initial_max_streams_uni (0x09):  The initial maximum unidirectional
#    streams parameter is an integer value that contains the initial
#    maximum number of unidirectional streams the endpoint that
#    receives this transport parameter is permitted to initiate.  If
#    this parameter is absent or zero, the peer cannot open
#    unidirectional streams until a MAX_STREAMS frame is sent.  Setting
#    this parameter is equivalent to sending a MAX_STREAMS
#    (Section 19.11) of the corresponding type with the same value.
# 
# ack_delay_exponent (0x0a):  The acknowledgment delay exponent is an
#    integer value indicating an exponent used to decode the ACK Delay
#    field in the ACK frame (Section 19.3).  If this value is absent, a
#    default value of 3 is assumed (indicating a multiplier of 8).
#    Values above 20 are invalid.
# 
# max_ack_delay (0x0b):  The maximum acknowledgment delay is an integer
#    value indicating the maximum amount of time in milliseconds by
#    which the endpoint will delay sending acknowledgments.  This value
#    SHOULD include the receiver's expected delays in alarms firing.
#    For example, if a receiver sets a timer for 5ms and alarms
#    commonly fire up to 1ms late, then it should send a max_ack_delay
#    of 6ms.  If this value is absent, a default of 25 milliseconds is
#    assumed.  Values of 2^14 or greater are invalid.
# 
# disable_active_migration (0x0c):  The disable active migration
#    transport parameter is included if the endpoint does not support
#    active connection migration (Section 9) on the address being used
#    during the handshake.  An endpoint that receives this transport
#    parameter MUST NOT use a new local address when sending to the
#    address that the peer used during the handshake.  This transport
#    parameter does not prohibit connection migration after a client
#    has acted on a preferred_address transport parameter.  This
#    parameter is a zero-length value.
# 
# preferred_address (0x0d):  The server's preferred address is used to
#    effect a change in server address at the end of the handshake, as
#    described in Section 9.6.  This transport parameter is only sent
#    by a server.  Servers MAY choose to only send a preferred address
#    of one address family by sending an all-zero address and port
#    (0.0.0.0:0 or [::]:0) for the other family.  IP addresses are
#    encoded in network byte order.
# 
#    The preferred_address transport parameter contains an address and
#    port for both IPv4 and IPv6.  The four-byte IPv4 Address field is
#    followed by the associated two-byte IPv4 Port field.  This is
#    followed by a 16-byte IPv6 Address field and two-byte IPv6 Port
#    field.  After address and port pairs, a Connection ID Length field
#    describes the length of the following Connection ID field.
#    Finally, a 16-byte Stateless Reset Token field includes the
#    stateless reset token associated with the connection ID.  The
#    format of this transport parameter is shown in Figure 22 below.
# 
#    The Connection ID field and the Stateless Reset Token field
#    contain an alternative connection ID that has a sequence number of
#    1; see Section 5.1.1.  Having these values sent alongside the
#    preferred address ensures that there will be at least one unused
#    active connection ID when the client initiates migration to the
#    preferred address.
# 
#    The Connection ID and Stateless Reset Token fields of a preferred
#    address are identical in syntax and semantics to the corresponding
#    fields of a NEW_CONNECTION_ID frame (Section 19.15).  A server
#    that chooses a zero-length connection ID MUST NOT provide a
#    preferred address.  Similarly, a server MUST NOT include a zero-
#    length connection ID in this transport parameter.  A client MUST
#    treat a violation of these requirements as a connection error of
#    type TRANSPORT_PARAMETER_ERROR.
# 
# Preferred Address {
#   IPv4 Address (32),
#   IPv4 Port (16),
#   IPv6 Address (128),
#   IPv6 Port (16),
#   Connection ID Length (8),
#   Connection ID (..),
#   Stateless Reset Token (128),
# }
# 
#                  Figure 22: Preferred Address Format
# 
# active_connection_id_limit (0x0e):  This is an integer value
#    specifying the maximum number of connection IDs from the peer that
#    an endpoint is willing to store.  This value includes the
#    connection ID received during the handshake, that received in the
#    preferred_address transport parameter, and those received in
#    NEW_CONNECTION_ID frames.  The value of the
#    active_connection_id_limit parameter MUST be at least 2.  An
#    endpoint that receives a value less than 2 MUST close the
#    connection with an error of type TRANSPORT_PARAMETER_ERROR.  If
#    this transport parameter is absent, a default of 2 is assumed.  If
#    an endpoint issues a zero-length connection ID, it will never send
#    a NEW_CONNECTION_ID frame and therefore ignores the
#    active_connection_id_limit value received from its peer.
# 
# initial_source_connection_id (0x0f):  This is the value that the
#    endpoint included in the Source Connection ID field of the first
#    Initial packet it sends for the connection; see Section 7.3.
# 
# retry_source_connection_id (0x10):  This is the value that the server
#    included in the Source Connection ID field of a Retry packet; see
#    Section 7.3.  This transport parameter is only sent by a server.
# 
# If present, transport parameters that set initial per-stream flow
# control limits (initial_max_stream_data_bidi_local,
# initial_max_stream_data_bidi_remote, and initial_max_stream_data_uni)
# are equivalent to sending a MAX_STREAM_DATA frame (Section 19.10) on
# every stream of the corresponding type immediately after opening.  If
# the transport parameter is absent, streams of that type start with a
# flow control limit of 0.
# 
# A client MUST NOT include any server-only transport parameter:
# original_destination_connection_id, preferred_address,
# retry_source_connection_id, or stateless_reset_token.  A server MUST
# treat receipt of any of these transport parameters as a connection
# error of type TRANSPORT_PARAMETER_ERROR.

[[spec]]
level = "MUST"
quote = '''
This transport parameter MUST NOT be sent
by a client but MAY be sent by a server.
'''

[[spec]]
level = "SHOULD"
quote = '''
This value
SHOULD include the receiver's expected delays in alarms firing.
'''

[[spec]]
level = "MUST"
quote = '''
An endpoint that receives this transport
parameter MUST NOT use a new local address when sending to the
address that the peer used during the handshake.
'''

[[spec]]
level = "MAY"
quote = '''
Servers MAY choose to only send a preferred address
of one address family by sending an all-zero address and port
(0.0.0.0:0 or [::]:0) for the other family.
'''

[[spec]]
level = "MUST"
quote = '''
A server
that chooses a zero-length connection ID MUST NOT provide a
preferred address.
'''

[[spec]]
level = "MUST"
quote = '''
Similarly, a server MUST NOT include a zero-
length connection ID in this transport parameter.
'''

[[spec]]
level = "MUST"
quote = '''
A client MUST
treat a violation of these requirements as a connection error of
type TRANSPORT_PARAMETER_ERROR.
'''

[[spec]]
level = "MUST"
quote = '''
The value of the
active_connection_id_limit parameter MUST be at least 2.
'''

[[spec]]
level = "MUST"
quote = '''
An
endpoint that receives a value less than 2 MUST close the
connection with an error of type TRANSPORT_PARAMETER_ERROR.
'''

[[spec]]
level = "MUST"
quote = '''
A client MUST NOT include any server-only transport parameter:
original_destination_connection_id, preferred_address,
retry_source_connection_id, or stateless_reset_token.
'''

[[spec]]
level = "MUST"
quote = '''
A server MUST
treat receipt of any of these transport parameters as a connection
error of type TRANSPORT_PARAMETER_ERROR.
'''