Follow the specification: the line is at most 107 bytes including CRLF,
ends with CRLF (not a bare LF), and fields are separated by exactly one
space, with nothing trailing (except after UNKNOWN). Ports are decimal
numbers up to 65535, without signs or leading zeroes. Also reject NUL
bytes and unknown address families (these were accepted before).
test_proxy_header_limits() now checks that malformed headers are
rejected, and also avoid DNS name resolution.
Assisted-by: Claude:claude-sonnet-5-5
85534724fa