target = "https://www.rfc-editor.org/rfc/rfc9000#section-10.2.1"

# 10.2.1.  Closing Connection State
#
# An endpoint enters the closing state after initiating an immediate
# close.
# 
# In the closing state, an endpoint retains only enough information to
# generate a packet containing a CONNECTION_CLOSE frame and to identify
# packets as belonging to the connection.  An endpoint in the closing
# state sends a packet containing a CONNECTION_CLOSE frame in response
# to any incoming packet that it attributes to the connection.
# 
# An endpoint SHOULD limit the rate at which it generates packets in
# the closing state.  For instance, an endpoint could wait for a
# progressively increasing number of received packets or amount of time
# before responding to received packets.
# 
# An endpoint's selected connection ID and the QUIC version are
# sufficient information to identify packets for a closing connection;
# the endpoint MAY discard all other connection state.  An endpoint
# that is closing is not required to process any received frame.  An
# endpoint MAY retain packet protection keys for incoming packets to
# allow it to read and process a CONNECTION_CLOSE frame.
# 
# An endpoint MAY drop packet protection keys when entering the closing
# state and send a packet containing a CONNECTION_CLOSE frame in
# response to any UDP datagram that is received.  However, an endpoint
# that discards packet protection keys cannot identify and discard
# invalid packets.  To avoid being used for an amplification attack,
# such endpoints MUST limit the cumulative size of packets it sends to
# three times the cumulative size of the packets that are received and
# attributed to the connection.  To minimize the state that an endpoint
# maintains for a closing connection, endpoints MAY send the exact same
# packet in response to any received packet.
# 
#    |  Note: Allowing retransmission of a closing packet is an
#    |  exception to the requirement that a new packet number be used
#    |  for each packet; see Section 12.3.  Sending new packet numbers
#    |  is primarily of advantage to loss recovery and congestion
#    |  control, which are not expected to be relevant for a closed
#    |  connection.  Retransmitting the final packet requires less
#    |  state.
# 
# While in the closing state, an endpoint could receive packets from a
# new source address, possibly indicating a connection migration; see
# Section 9.  An endpoint in the closing state MUST either discard
# packets received from an unvalidated address or limit the cumulative
# size of packets it sends to an unvalidated address to three times the
# size of packets it receives from that address.
# 
# An endpoint is not expected to handle key updates when it is closing
# (Section 6 of [QUIC-TLS]).  A key update might prevent the endpoint
# from moving from the closing state to the draining state, as the
# endpoint will not be able to process subsequently received packets,
# but it otherwise has no impact.

[[spec]]
level = "SHOULD"
quote = '''
An endpoint SHOULD limit the rate at which it generates packets in
the closing state.
'''

[[spec]]
level = "MAY"
quote = '''
An endpoint's selected connection ID and the QUIC version are
sufficient information to identify packets for a closing connection;
the endpoint MAY discard all other connection state.
'''

[[spec]]
level = "MAY"
quote = '''
An
endpoint MAY retain packet protection keys for incoming packets to
allow it to read and process a CONNECTION_CLOSE frame.
'''

[[spec]]
level = "MAY"
quote = '''
An endpoint MAY drop packet protection keys when entering the closing
state and send a packet containing a CONNECTION_CLOSE frame in
response to any UDP datagram that is received.
'''

[[spec]]
level = "MUST"
quote = '''
To avoid being used for an amplification attack,
such endpoints MUST limit the cumulative size of packets it sends to
three times the cumulative size of the packets that are received and
attributed to the connection.
'''

[[spec]]
level = "MAY"
quote = '''
To minimize the state that an endpoint
maintains for a closing connection, endpoints MAY send the exact same
packet in response to any received packet.
'''

[[spec]]
level = "MUST"
quote = '''
An endpoint in the closing state MUST either discard
packets received from an unvalidated address or limit the cumulative
size of packets it sends to an unvalidated address to three times the
size of packets it receives from that address.
'''