State-of-the-art C routines provided as easy-to-use library for Internet services.
Scope: What are the fehQlibs?
The software of Dan Bernstein (qmail, ucspi-tcp, djbdns) include supplementary C routines which obsoletes the usage of C's STDIO lib while replacing those by some safer implementations, in particular for string handling.
All this material is now public domain and the fehQlibs provide a basic framework for byte, string, I/O, socket, and IPv4/IPv6 handling in addition with the constant database cdb together with dnsstub resolver routines for Internet services applying the same or an even enhanced API.
The approach includes two main archives
- qlibs.a together with libqlibs.so and
- dnsresolv.a joined by (libdnsresolv.so)
simply to be linked (statically) with some IP applications without the hustle to care about the implemtation basics, header files, and potential bugs in here. Applications can focus on their duty and don't need to re-implement the basics.
The fehQlibs don't include any application routines but rather can be compiled and installed on most Unix system; serving as library only. Different from Dan Bernstein's implementation is the IPv6 conformance throughout and the error/log message interface.
The included dnsresolv stub library supports full IPv6 capabilities though without encryption.
History: Some background
Dan Bernstein used a series of own developed C routines as a replacement of the buggy and occassionally bloated C-library. Additional programs were included, providing services for a Constant Database (cdb), IPv4 address parsing and manipulation, IPv4 sockets and a DNS stub resolver.
These programs are kept stable and functioning over several software products Dan released over the years. However, some changes did occure, namely the use of buffer instead of substdio providing some better abstraction.
Felix von Leitner (and probably many others) used those routines as base for own releases, now put under the GNU license scheme (libowfat, djblib) and extending it's functionality significantly while including IPv6 support.
Kai Peter published an own djblib clone qlibs which was the starting point of fehQlibs. Given my previous experiences with Dan's routines, my objectives are to provide a clean socket interface for IPv4/IPv6 without the often needed case decisions. In addition, the dnsstub resolver has been upgraded to support IPv6 Link-local addresses (LLU) together with all the other IPv6 routines; allowing an additional interface-index to be included.
My attempt to use fehQlibs in version 10 for the forthcoming s/qmail based on those, required some additional enhancements, in particular for the dns stub resolver routines. The original qmail code uses the standards BIND API; unlike the more 'modern' SW packages of DJB. The current version of fehQlibs include these changes, though making it slightly incompatibel with previous versions given the DNS return codes.
Given its current '19'th implementation the fehQlibs are 'mature' now to work in any environment; even with disabled IPv6 in the kernel.
Implementation: The details
The fehQlibs - though functionally complete - are in particular suited for devices with little resources only, IoT devices in particular. On the other hand, they perform extremely well for larger projects.
The following is the exhaustive list of '*.c' routines to be compiled provided by scope:
|Byte handling/ manipulation||byte.c, uint16p.c, uint32p.c, uint64p.c, uint128p.c|
|String handling/ manipulation||case.c, scan.c, str.c, ,stralloc.c, fmt.c|
|Input/output handling||buffer.c, fd.c, getln.c, getoptb.c, open.c, seek.c, readclose.c|
|IP address handling/ manipulation||ip4.c, ip6.c|
|Socket routines||socket_bind.c, socket_connect.c socket_if.c socket_info.c socket_recv.c socket_send.c, socket_setup.c, socket_tcp.c socket_udp.c|
|Network communication||timeout.c, timoutconn.c|
|Interprocess communication||iopause.c, lock.c ndelay.c pathexec.c, sig,c, wait.c|
|Databases||constmap.c, cdbmake.c, cdbread.c|
|Time routines||tai.c, taia.c|
|DNS stub routines||dns_ip.c, dns_cname.c, dns_name.c, dns_txt.c, dns_mx.c|
|DNS low level routines||dns_dfd.c, dns_domain.c, dns_dtda.c, dns_ipq.c, dns_nd.c, dns_packet.c, dns_random.c, dns_resolve.c, dns_rcip.c, dns_rcrw.c, dns_sortip.c, dns_transmit.c|
|Version & Download||Description||Verification|
|fehQlibs-20||fehQlibs 20 incorporates dns_txt.c from djbdnscurv6-43 in order to successfully extract DKIM's pubkey from DNS.||MD5 (fehQlibs-20.tgz) = aecd196025f6b316ca311b88113933b7
|fehQlibs-19||fehQlibs 19 include now again IPv4 socket calls, which I believed are outdated and additional data types.||MD5 (fehQlibs-19.tgz) = 9ab8703dfc510958fb6befa822ed7bad
|fehQlibs-18||fehQlibs 18 provides now better IPv4 compatibility, as required in case the OS does not like IPv6-mapped IPv4 addresses.||MD5 (fehQlibs-18.tgz) = 3a0b1efbeb0d2253d4b5b032858dac0b
|fehQlibs-17||fehQlibs 17 takes care of GCC-10 and avoids strong coupling to the socket routines given by ipv4socket which is removed now.||MD5 (fehQlibs-17.tgz) = e7c73bb712377d6e9408db77ecaac5b1
Build: 20210402232728 (new!)
|fehQlibs-15b||fehQlibs 15 coming with an improved DNSStub resolver library and including the Guninski fix for alloc while providing full GCC 10 compliance.||MD5 (fehQlibs-15b.tgz) = 521c07eddd9b6d3137d61d7b4c8a788a
|fehQlibs-14||Valentin's fehQlibs 14 is a small enhancement to support SRS in s/qmail and introducing some compiler friendly input arg declarations while supporting Gentoo builds.||MD5 (fehQlibs-14.tgz) = 8f41b733f181046d9a56863ed4adda0f
|fehQlibs-13d||fehQlibs with enhanced/changed DNS stub resolver suited for s/qmail and streamlined DNS error return codes with djbdnscurve6-36 and fixed dnsip/dnsmx clients.||MD5 (fehQlibs-13d.tgz) = 478da0ad6b2a8cbea7ca7b0e7b007792
|fehQlibs-10b||Previous release of fehQlibs (10); now with fixed str_copy and inclusion of the str_copyb routine.||MD5 (fehQlibs-10b.tgz) = e39dfebd72fd7bc8f1055dce823d3239
The source code of fehQlibs-19 is documented in doxygen.
Installation is pretty easy:
- Untar the downloaded tar-file under /usr/local/.
- Compile it, while calling make within the directory ./fehQlibs-xy.
- I recommend to link this directory to /usr/local/qlibs for convenience (ln -s fehQlibs-xy qlibs).
- If required, install the man-files available under ./man in section 3 of your man directory manually.
That's it! The fehQlibs are a library. No executables are installed!
Usage with my routines (ucspi-tcp6, ucspi-ssl, djbdnscurve6)
Once you have downloaded and installed the fehQlibs, I expect those to be symlinked to /usr/local/qlibs.
However, if you provide the fehQlibs in a different directory, customize the configuration file conf-qlibs to comply with your settings.
Using fehQlibs requires just two steps:
Assuming your source code calls any of the routines
- include the location of the header files while calling the compiler; typically I use: cc -O2 -Wall -I/usr/local/qlibs/include
- tell the linker to use the qlibs and potentially dnsresolv libraries: cc -s -L/usr/local/qlibs -lqlibs -ldnsresolv
In case, you have projects based on Dan's strerr messages you need to include those as source code.
fehQlibs are known to install well and work under Linux (32/64 bit) on x86, FreeBSD, OmniOs, RasPi (Raspbian/FreeBSD 12), MacOS X (x86, PPC).
Tickets, Change Requests, Changelog & Communication
An EZMLM mailing list keeps you updated with current developments, bug fixes, and features discussed. This list also can be used to file
- Defects (bug reports) and
- Change Requests (enhancements).
To inscribe use: fehQlib's mailing list
As usual, I can't guarantee a certain response level; but reasonable issues will be answered.
Errata & Changelog
|fehQlibs-20||Added provissional uint8p support and enhanced dns_txt.c to extract labels in RDATA section correctly.|
|fehQlibs-19||To provide better IPv4 compatibility, outdated IPv4 socket calls included plus uint8 as data type.|
|fehQlibs-18||Decision whether to use UDP/TCP over IPv4 or IPv6 connections is now based on the remote IP.|
|fehQlibs-17||Removed 'external' variable ipv4socket in order to be GCC-10 compliant. This means, one has to care about IPv4 and IPv6 sockets on call and can't delegate it to socket routines by means of a common global variable.|
|fehQlibs-16||Added constmap.c/.h from qmail to support mess822x. dnsip accepts now bracketed IP addresses. Minor docu fixes. Renamed 'ipv4|6-looback' and 'ipv4|6-localhoast' to 'ip4|4-loopback' and 'ip4|6-localhost' to be compliant with Ubuntu.|
|fehQlibs-15b||Convenience release fixing all GCC 10 compatibility issues and defining DNS TLSA records with correct value.|
|fehQlibs-15a||Convenience release to cope with 'external' settings as required by GCC-10 and streamlining some DNS return codes.|
|fehQlibs-15||Improved and enhanced dns_ip[4|6]_qualify. Included fix for Guninski's CVE 2005-1513.|
|fehQlibs-14||Added byte_fill and case_upper. Declared most input args 'const'. Gentoo build friendly now.|
|fehQlibs-13d||Fixed integration bug for dns_ip/dns_mx client functions not returning IPv6 addresses.|
|fehQlibs-13c||DNS stub resolver error return codes adjusted and aligned with djbdnscurve6-36.|
|fehQlibs-13b||During integration, the function str_copyb was lost,
though the internal documention says it was included for str.c.
This function is required for SRS in s/qmail (only).
|fehQlibs-13a||Fixed potential wrong 'negative' evalution of DNSCACHEIP in dns_rcip.c
Improved man pages.
|fehQlibs-13||New dnsstub resolver routines finished.
Version used for s/qmail and ucspi-X-y.11.* and the djbdnscurve6 > 35.
|fehQlibs-12/a/b/c||Experimental versions with enhanced dnsstub resolver routines.|
|fehQlibs-11||Unpublished and never used version of fehQlibs.||fehQlibs-10b||Included missing str_copyb function.|
|fehQlibs-10a|| Improved handling of poll and select calls
while using their return codes in addition.
Fixed wrong nesting of paranthesis in str_copy.
Added functions socket_dualstack and socket_nodualstack (providing better compatibility for OS which use socket option IPV6_V6ONLY).
For some backgrund on poll and IPV6_V6ONLY check
(a) Marek's (totally not insane) idea of the day
(b) Re: Disabling IPV6_V6ONLY a bad idea?
Added the 'shared object' (PIC) libqlibs.so and libdnsresolv.so libraries upon generation.
Attached LICENSE and CHANGELOG file.