Rich Felker
a4ecaf89a9
in the event of chained CNAMEs, the answer to a query will contain the entire CNAME chain, not just one CNAME record. previously, the answer buffer size had been chosen to admit a maximal-length CNAME, but only one. a moderate-length chain could fill the available 768 bytes leaving no room for an actual address answering the query. while the DNS RFCs do not specify any limit on the length of a CNAME chain, or any reasonable behavior is the chain exceeds the entire 64k possible message size, actual recursive servers have to impose a limit, and a such, for all practical purposes, chains longer than this limit are not usable. it turns out BIND has a hard-coded limit of 16, and Unbound has a default limit of 11. assuming the recursive server makes use of "compression" (pointers), each maximal-length CNAME record takes at most 268 bytes, and thus any chain up to length 16 fits in at most 4288 bytes. this patch increases the answer buffer size to preserve the original intent of having 512 bytes available for address answers, plus space needed for a maximal CNAME chain, for a total of 4800 bytes. the resulting size of 9600 bytes for two queries (A+AAAA) is still well within what is reasonable to place in automatic storage.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/