Most OS platforms have already provided solutions to
Y2038 32-bit signed time_t 5 - 10 years ago (or more!)
Notable exceptions are Linux i686 and FreeBSD i386.
Since 32-bit systems tend to be embedded systems,
and since many distros take years to pick up new software,
this commit aims to provide Y2038 mitigations for lighttpd
running on 32-bit systems with Y2038-unsafe 32-bit signed time_t
* Y2038: lighttpd 1.4.60 and later report Y2038 safety
$ lighttpd -V
+ Y2038 support # Y2038-SAFE
$ lighttpd -V
- Y2038 support (unsafe 32-bit signed time_t) # Y2038-UNSAFE
* Y2038: general platform info
* Y2038-SAFE: lighttpd 64-bit builds on platforms using 64-bit time_t
- all major 64-bit platforms (known to this author) use 64-bit time_t
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 64-bit time_t
- Linux x32 ABI (different from i686)
- FreeBSD all 32-bit and 64-bit architectures *except* 32-bit i386
- NetBSD 6.0 (released Oct 2012) all 32-bit and 64-bit architectures
- OpenBSD 5.5 (released May 2014) all 32-bit and 64-bit architectures
- Microsoft Windows XP and Visual Studio 2005 (? unsure ?)
Another reference suggests Visual Studio 2015 defaults to 64-bit time_t
- MacOS 10.15 Catalina (released 2019) drops support for 32-bit apps
* Y2038-SAFE: lighttpd 32-bit builds on platforms using 32-bit unsigned time_t
- e.g. OpenVMS (unknown if lighttpd builds on this platform)
* Y2038-UNSAFE: lighttpd 32-bit builds on platforms using 32-bit signed time_t
- Linux 32-bit (including i686)
- glibc 32-bit library support not yet available for 64-bit time_t
- https://sourceware.org/glibc/wiki/Y2038ProofnessDesign
- Linux kernel 5.6 on 32-bit platforms does support 64-bit time_t
https://itsubuntu.com/linux-kernel-5-6-to-fix-the-year-2038-issue-unix-y2k/
- https://www.gnu.org/software/libc/manual/html_node/64_002dbit-time-symbol-handling.html
"Note: at this point, 64-bit time support in dual-time
configurations is work-in-progress, so for these
configurations, the public API only makes the 32-bit time
support available. In a later change, the public API will
allow user code to choose the time size for a given
compilation unit."
- compiling with -D_TIME_BITS=64 currently has no effect
- glibc recent (Jul 2021) mailing list discussion
- https://public-inbox.org/bug-gnulib/878s2ozq70.fsf@oldenburg.str.redhat.com/T/
- FreeBSD i386
- DragonFlyBSD 32-bit
* Y2038 mitigations attempted on Y2038-UNSAFE platforms (32-bit signed time_t)
* lighttpd prefers system monotonic clock instead of realtime clock
in places where realtime clock is not required
* lighttpd treats negative time_t values as after 19 Jan 2038 03:14:07 GMT
* (lighttpd presumes that lighttpd will not encounter dates before 1970
during normal operation.)
* lighttpd casts struct stat st.st_mtime (and st.st_*time) through uint64_t
to convert negative timestamps for comparisions with 64-bit timestamps
(treating negative timestamp values as after 19 Jan 2038 03:14:07 GMT)
* lighttpd provides unix_time64_t (int64_t) and
* lighttpd provides struct unix_timespec64 (unix_timespec64_t)
(struct timespec equivalent using unix_time64_t tv_sec member)
* lighttpd provides gmtime64_r() and localtime64_r() wrappers
for platforms 32-bit platforms using 32-bit time_t and
lighttpd temporarily shifts the year in order to use
gmtime_r() and localtime_r() (or gmtime() and localtime())
from standard libraries, before readjusting year and passing
struct tm to formatting functions such as strftime()
* lighttpd provides TIME64_CAST() macro to cast signed 32-bit time_t to
unsigned 32-bit and then to unix_time64_t
* Note: while lighttpd tries handle times past 19 Jan 2038 03:14:07 GMT
on 32-bit platforms using 32-bit signed time_t, underlying libraries and
underlying filesystems might not behave properly after 32-bit signed time_t
overflows (19 Jan 2038 03:14:08 GMT). If a given 32-bit OS does not work
properly using negative time_t values, then lighttpd likely will not work
properly on that system.
* Other references and blogs
- https://en.wikipedia.org/wiki/Year_2038_problem
- https://en.wikipedia.org/wiki/Time_formatting_and_storage_bugs
- http://www.lieberbiber.de/2017/03/14/a-look-at-the-year-20362038-problems-and-time-proofness-in-various-systems/
reuse cache lookup in common case of serving a static file
rather than repeating the stat_cache_entry lookup
(which is more work than memcmp() to re-check stat_cache_entry match)
http_request_parse_header() specialized for HTTP/2 request headers
to be parsed as each field-name and value is HPACK-decoded; send headers
directly from HPACK decoder, rather than double-buffering in chunkqueue
http_request_headers_process_h2() for post-processing
(subsequently incrementally updated using git rebase)
huge props and many thank yous to writers of testing tools used while
developing HTTP/2 support in lighttpd:
h2spec - conformance testing tool for HTTP/2 implementation
https://github.com/summerwind/h2spec
h2load - HTTP/2 benchmarking tool
https://nghttp2.org/documentation/h2load-howto.html
curl - command line tool and library for transferring data with URLs
https://curl.haxx.se/
reset connection counters per connection, not per request
adjust mod_accesslog and mod_rrdtool usage
continue to count mod_rrdtool per request rather than per connection
so that data is updated after each request, rather than aggregated
to the end of a potentially long-lived connection with many keep-alives.
decode Transfer-Encoding: chunked from gw (gateway backends)
Transfer-Encoding: chunked is a hop-by-hop header.
Handling chunked encoding remove a hurdle for mod_proxy to send HTTP/1.1
requests to backends and be able to handle HTTP/1.1 responses.
Other backends ought not to send Transfer-Encoding: chunked, but in
practice, some implementations do.
NB: r->tmp_buf == srv->tmp_buf (pointer is copied for quicker access)
NB: request read and write chunkqueues currently point to connection
chunkqueues; per-request and per-connection chunkqueues are
not distinct from one another
con->read_queue == r->read_queue
con->write_queue == r->write_queue
NB: in the future, a separate connection config may be needed for
connection-level module hooks. Similarly, might need to have
per-request chunkqueues separate from per-connection chunkqueues.
Should probably also have a request_reset() which is distinct from
connection_reset().
server.http-parseopts = ( ... ) URL normalization options
Note: *not applied* to CONNECT method
Note: In a future release, URL normalization likely enabled by default
(normalize URL, reject control chars, remove . and .. path segments)
To prepare for this change, lighttpd.conf configurations should
explicitly select desired behavior by enabling or disabling:
server.http-parseopts = ( "url-normalize" => "enable", ... )
server.http-parseopts = ( "url-normalize" => "disable" )
x-ref:
"lighttpd ... compares URIs to patterns in the (1) url.redirect and (2) url.rewrite configuration settings before performing URL decoding, which might allow remote attackers to bypass intended access restrictions, and obtain sensitive information or possibly modify data."
https://www.cvedetails.com/cve/CVE-2008-4359/
"Rewrite/redirect rules and URL encoding"
https://redmine.lighttpd.net/issues/1720
provide standard types in first.h instead of base.h
provide lighttpd types in base_decls.h instead of settings.h
reduce headers exposed by headers for core data structures
do not expose <pcre.h> or <stdlib.h> in headers
move stat_cache_entry to stat_cache.h
reduce use of "server.h" and "base.h" in headers
server.http-parseopt-header-strict = "enable"
server.http-parseopt-host-strict = "enable" (implies host-normalize)
server.http-parseopt-host-normalize = "disable"
defaults retain current behavior, which is strict header parsing
and strict host parsing, with enhancement to normalize IPv4 address
and port number strings.
For lighttpd tests, these need to be enabled (and are by default)
For marginally faster HTTP header parsing for benchmarks, disable these.
To allow
- underscores in hostname
- hypen ('-') at beginning of hostname
- all-numeric TLDs
server.http-parseopt-host-strict = "disable"
x-ref:
"lighttpd doesn't allow underscores in host names"
https://redmine.lighttpd.net/issues/551
"hyphen in hostname"
https://redmine.lighttpd.net/issues/1086
"a numeric tld"
https://redmine.lighttpd.net/issues/1184
"Numeric tld's"
https://redmine.lighttpd.net/issues/2143
"Bad Request"
https://redmine.lighttpd.net/issues/2258
"400 Bad Request when using Numeric TLDs"
https://redmine.lighttpd.net/issues/2281
To allow a variety of numerical formats to be converted to IP addresses
server.http-parseopt-host-strict = "disable"
server.http-parseopt-host-normalize = "enable"
x-ref:
"URL encoding leads to "400 - Bad Request""
https://redmine.lighttpd.net/issues/946
"400 Bad Request when using IP's numeric value ("ip2long()")"
https://redmine.lighttpd.net/issues/1330
To allow most 8-bit and 7-bit chars in headers
server.http-parseopt-header-strict = "disable" (not recommended)
x-ref:
"Russian letters not alowed?"
https://redmine.lighttpd.net/issues/602
"header Content-Disposition with russian '?' (CP1251, ascii code 255) causes error"
https://redmine.lighttpd.net/issues/1016
Glenn Strauss
Jan Kneschke