curl/lib/README.hostip
Colin Hogben 0ab9e0c9d9 lib: documentation updates in README.hostip
c-ares now does support IPv6;
avoid implying threaded resolver is Windows-only;
two referenced source files were renamed in 7de2f92
2014-06-21 19:49:48 +02:00

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hostip.c explained
==================
The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
source file are these:
CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
that. The host may not be able to resolve IPv6, but we don't really have to
take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
defined.
CURLRES_ARES - is defined if libcurl is built to use c-ares for asynchronous
name resolves. This can be Windows or *nix.
CURLRES_THREADED - is defined if libcurl is built to use threading for
asynchronous name resolves. The name resolve will be done in a new thread,
and the supported asynch API will be the same as for ares-builds. This is
the default under (native) Windows.
If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
defined.
The host*.c sources files are split up like this:
hostip.c - method-independent resolver functions and utility functions
hostasyn.c - functions for asynchronous name resolves
hostsyn.c - functions for synchronous name resolves
asyn-ares.c - functions for asynchronous name resolves using c-ares
asyn-thread.c - functions for asynchronous name resolves using threads
hostip4.c - ipv4-specific functions
hostip6.c - ipv6-specific functions
The hostip.h is the single united header file for all this. It defines the
CURLRES_* defines based on the config*.h and curl_setup.h defines.