target = "https://tools.ietf.org/rfc/rfc8446#appendix-D.2"

# D.2.  Negotiating with an Older Client
#
# A TLS server can also receive a ClientHello indicating a version
# number smaller than its highest supported version.  If the
# "supported_versions" extension is present, the server MUST negotiate
# using that extension as described in Section 4.2.1.  If the
# "supported_versions" extension is not present, the server MUST
# negotiate the minimum of ClientHello.legacy_version and TLS 1.2.  For
# example, if the server supports TLS 1.0, 1.1, and 1.2, and
# legacy_version is TLS 1.0, the server will proceed with a TLS 1.0
# ServerHello.  If the "supported_versions" extension is absent and the
# server only supports versions greater than
# ClientHello.legacy_version, the server MUST abort the handshake with
# a "protocol_version" alert.
# 
# Note that earlier versions of TLS did not clearly specify the record
# layer version number value in all cases
# (TLSPlaintext.legacy_record_version).  Servers will receive various
# TLS 1.x versions in this field, but its value MUST always be ignored.

[[spec]]
level = "MUST"
quote = '''
If the
"supported_versions" extension is present, the server MUST negotiate
using that extension as described in Section 4.2.1.
'''

[[spec]]
level = "MUST"
quote = '''
If the
"supported_versions" extension is not present, the server MUST
negotiate the minimum of ClientHello.legacy_version and TLS 1.2.
'''

[[spec]]
level = "MUST"
quote = '''
If the "supported_versions" extension is absent and the
server only supports versions greater than
ClientHello.legacy_version, the server MUST abort the handshake with
a "protocol_version" alert.
'''

[[spec]]
level = "MUST"
quote = '''
Servers will receive various
TLS 1.x versions in this field, but its value MUST always be ignored.
'''

