target = "https://www.rfc-editor.org/rfc/rfc9000#section-8.2.1"

# 8.2.1.  Initiating Path Validation
#
# To initiate path validation, an endpoint sends a PATH_CHALLENGE frame
# containing an unpredictable payload on the path to be validated.
# 
# An endpoint MAY send multiple PATH_CHALLENGE frames to guard against
# packet loss.  However, an endpoint SHOULD NOT send multiple
# PATH_CHALLENGE frames in a single packet.
# 
# An endpoint SHOULD NOT probe a new path with packets containing a
# PATH_CHALLENGE frame more frequently than it would send an Initial
# packet.  This ensures that connection migration is no more load on a
# new path than establishing a new connection.
# 
# The endpoint MUST use unpredictable data in every PATH_CHALLENGE
# frame so that it can associate the peer's response with the
# corresponding PATH_CHALLENGE.
# 
# An endpoint MUST expand datagrams that contain a PATH_CHALLENGE frame
# to at least the smallest allowed maximum datagram size of 1200 bytes,
# unless the anti-amplification limit for the path does not permit
# sending a datagram of this size.  Sending UDP datagrams of this size
# ensures that the network path from the endpoint to the peer can be
# used for QUIC; see Section 14.
# 
# When an endpoint is unable to expand the datagram size to 1200 bytes
# due to the anti-amplification limit, the path MTU will not be
# validated.  To ensure that the path MTU is large enough, the endpoint
# MUST perform a second path validation by sending a PATH_CHALLENGE
# frame in a datagram of at least 1200 bytes.  This additional
# validation can be performed after a PATH_RESPONSE is successfully
# received or when enough bytes have been received on the path that
# sending the larger datagram will not result in exceeding the anti-
# amplification limit.
# 
# Unlike other cases where datagrams are expanded, endpoints MUST NOT
# discard datagrams that appear to be too small when they contain
# PATH_CHALLENGE or PATH_RESPONSE.

[[spec]]
level = "MAY"
quote = '''
An endpoint MAY send multiple PATH_CHALLENGE frames to guard against
packet loss.
'''

[[spec]]
level = "SHOULD"
quote = '''
However, an endpoint SHOULD NOT send multiple
PATH_CHALLENGE frames in a single packet.
'''

[[spec]]
level = "SHOULD"
quote = '''
An endpoint SHOULD NOT probe a new path with packets containing a
PATH_CHALLENGE frame more frequently than it would send an Initial
packet.
'''

[[spec]]
level = "MUST"
quote = '''
The endpoint MUST use unpredictable data in every PATH_CHALLENGE
frame so that it can associate the peer's response with the
corresponding PATH_CHALLENGE.
'''

[[spec]]
level = "MUST"
quote = '''
An endpoint MUST expand datagrams that contain a PATH_CHALLENGE frame
to at least the smallest allowed maximum datagram size of 1200 bytes,
unless the anti-amplification limit for the path does not permit
sending a datagram of this size.
'''

[[spec]]
level = "MUST"
quote = '''
To ensure that the path MTU is large enough, the endpoint
MUST perform a second path validation by sending a PATH_CHALLENGE
frame in a datagram of at least 1200 bytes.
'''

[[spec]]
level = "MUST"
quote = '''
Unlike other cases where datagrams are expanded, endpoints MUST NOT
discard datagrams that appear to be too small when they contain
PATH_CHALLENGE or PATH_RESPONSE.
'''