target = "https://www.rfc-editor.org/rfc/rfc9000#section-17.2.2"

# 17.2.2.  Initial Packet
#
# An Initial packet uses long headers with a type value of 0x00.  It
# carries the first CRYPTO frames sent by the client and server to
# perform key exchange, and it carries ACK frames in either direction.
# 
# Initial Packet {
#   Header Form (1) = 1,
#   Fixed Bit (1) = 1,
#   Long Packet Type (2) = 0,
#   Reserved Bits (2),
#   Packet Number Length (2),
#   Version (32),
#   Destination Connection ID Length (8),
#   Destination Connection ID (0..160),
#   Source Connection ID Length (8),
#   Source Connection ID (0..160),
#   Token Length (i),
#   Token (..),
#   Length (i),
#   Packet Number (8..32),
#   Packet Payload (8..),
# }
# 
#                       Figure 15: Initial Packet
# 
# The Initial packet contains a long header as well as the Length and
# Packet Number fields; see Section 17.2.  The first byte contains the
# Reserved and Packet Number Length bits; see also Section 17.2.
# Between the Source Connection ID and Length fields, there are two
# additional fields specific to the Initial packet.
# 
# Token Length:  A variable-length integer specifying the length of the
#    Token field, in bytes.  This value is 0 if no token is present.
#    Initial packets sent by the server MUST set the Token Length field
#    to 0; clients that receive an Initial packet with a non-zero Token
#    Length field MUST either discard the packet or generate a
#    connection error of type PROTOCOL_VIOLATION.
# 
# Token:  The value of the token that was previously provided in a
#    Retry packet or NEW_TOKEN frame; see Section 8.1.
# 
# In order to prevent tampering by version-unaware middleboxes, Initial
# packets are protected with connection- and version-specific keys
# (Initial keys) as described in [QUIC-TLS].  This protection does not
# provide confidentiality or integrity against attackers that can
# observe packets, but it does prevent attackers that cannot observe
# packets from spoofing Initial packets.
# 
# The client and server use the Initial packet type for any packet that
# contains an initial cryptographic handshake message.  This includes
# all cases where a new packet containing the initial cryptographic
# message needs to be created, such as the packets sent after receiving
# a Retry packet; see Section 17.2.5.
# 
# A server sends its first Initial packet in response to a client
# Initial.  A server MAY send multiple Initial packets.  The
# cryptographic key exchange could require multiple round trips or
# retransmissions of this data.
# 
# The payload of an Initial packet includes a CRYPTO frame (or frames)
# containing a cryptographic handshake message, ACK frames, or both.
# PING, PADDING, and CONNECTION_CLOSE frames of type 0x1c are also
# permitted.  An endpoint that receives an Initial packet containing
# other frames can either discard the packet as spurious or treat it as
# a connection error.
# 
# The first packet sent by a client always includes a CRYPTO frame that
# contains the start or all of the first cryptographic handshake
# message.  The first CRYPTO frame sent always begins at an offset of
# 0; see Section 7.
# 
# Note that if the server sends a TLS HelloRetryRequest (see
# Section 4.7 of [QUIC-TLS]), the client will send another series of
# Initial packets.  These Initial packets will continue the
# cryptographic handshake and will contain CRYPTO frames starting at an
# offset matching the size of the CRYPTO frames sent in the first
# flight of Initial packets.

[[spec]]
level = "MUST"
quote = '''
Initial packets sent by the server MUST set the Token Length field
to 0; clients that receive an Initial packet with a non-zero Token
Length field MUST either discard the packet or generate a
connection error of type PROTOCOL_VIOLATION.
'''

[[spec]]
level = "MUST"
quote = '''
Initial packets sent by the server MUST set the Token Length field
to 0; clients that receive an Initial packet with a non-zero Token
Length field MUST either discard the packet or generate a
connection error of type PROTOCOL_VIOLATION.
'''

[[spec]]
level = "MAY"
quote = '''
A server MAY send multiple Initial packets.
'''