* Reject a Range first-byte-pos that overflows ssize_t
parse_range_header initializes first to the -1 sentinel that means "no
first-byte-pos" and only overwrites it when detail::from_chars succeeds.
On std::errc::result_out_of_range the assignment is skipped and -1
survives, so "bytes=9223372036854775808-100" is parsed as the suffix
range "bytes=-100" and range_error serves the last 100 bytes instead of
returning 416.
Before the parser was rewritten onto detail::from_chars, std::stoll threw
std::out_of_range on the same input, the catch arm added in 8f8761e for
issue #705 returned false, and the request was answered with 416. The
catch arm is still there but from_chars reports through an error code, so
nothing reaches it any more.
get_header_value_u64 and parse_port already reject an out-of-range value
at their from_chars call sites; this was the remaining one that dropped
the error.
The last-byte-pos side is deliberately unchanged: -1 there is the
documented RFC 9110 14.1.2 "remainder of the representation" value, so an
oversized last-byte-pos stays accepted.
* Simplify the Range first-byte-pos overflow check
Parse the first-byte-pos straight into first, since a failed parse now
returns before first is read, and fold the overflow test into the
existing batch of rejected ranges. Also note on the last-byte-pos side
why an overflow there deliberately keeps -1.
Claude-Session: https://claude.ai/code/session_01JYPWKpbp4a881EdpEf2xSi
---------
Co-authored-by: yhirose <yuji.hirose.bug@gmail.com>
