Crate c_ares

A safe wrapper for the c-ares library.

This crate is a fairly faithful wrapper of c-ares; which is to say that it preserves some of the complication of using the underlying library:

• Direct usage of this crate requires you to pay attention to c-ares as it tells you which file descriptors it cares about, and to poll for activity on those file descriptors.

• This likely requires you to have an event loop or similar with which to integrate.

If that sounds a bit too much like hard work, you should probably prefer the c-ares-resolver crate, which takes care of all that stuff for you and presents a much simpler API.

Still here? Usage of this crate is as follows:

• Create a Channel.

• Make queries on the Channel. Queries all take callbacks, which will be called when the query completes.

• Have c-ares tell you what file descriptors to listen on for read and / or write events. You can do this either by providing a callback, which is called whenever the set of interesting file descriptors changes, or by querying the Channel directly either with get_sock() or with fds().

• Do as c-ares asks. That is, listen for the events that it requests, on the file descriptors that it cares about.

• When a file descriptor becomes readable or writable, call either process_fd() or process() on the Channel to tell c-ares what has happened.

• If you have queries pending and don't see events happening, you still need to call either process_fd() or process() at some point anyway - to give c-ares an opportunity to process any requests that have timed out.

Complete examples showing how to use the library can be found here.

Modules

flags	Flags that may be passed when initializing a Channel.
ni_flags	Flags that may be provided on a call to get_name_info()

Structs

AAAAResult	The contents of a single AAAA record.
AAAAResults	The result of a successful AAAA lookup.
AAAAResultsIter	Iterator of AAAAResults.
AResult	The contents of a single A record.
AResults	The result of a successful A lookup.
AResultsIter	Iterator of AResults.
CNameResults	The result of a successful CNAME lookup.
Channel	A channel for name service lookups.
GetSock	Information about the set of sockets that c-ares is interested in, as returned by get_sock().
GetSockIter	Iterator for sockets of interest to c-ares.
HostAddressResultsIter	Iterator of IpAddrs.
HostAliasResultsIter	Iterator of &'a strs.
HostResults	The result of a successful host lookup.
MXResult	The contents of a single MX record.
MXResults	The result of a successful MX lookup.
MXResultsIter	Iterator of MXResults.
NAPTRResult	The contents of a single NAPTR record.
NAPTRResults	The result of a successful NAPTR lookup.
NAPTRResultsIter	Iterator of NAPTRResults.
NSResults	The result of a successful NS lookup.
NameInfoResult	The result of a successful name-info lookup.
Options	Used to configure the behaviour of the name resolver.
PTRResults	The result of a successful PTR lookup.
SOAResult	The result of a successful SOA lookup.
SRVResult	The contents of a single SRV record.
SRVResults	The result of a successful SRV lookup.
SRVResultsIter	Iterator of SRVResults.
TXTResult	The contents of a single TXT record.
TXTResults	The result of a successful TXT lookup.
TXTResultsIter	Iterator of TXTResults.

Enums

AddressFamily	Address families.
Error	Error codes that the library might return.

Constants

SOCKET_BAD

An invalid socket / file descriptor. Use this to represent 'no action' when calling process_fd() on a channel.

Functions

version

Get the version number of the underlying c-ares library.

Type Definitions

Result	The type used by this library for methods that might fail.
Socket	The platform-specific file descriptor / socket type. That is, either a RawFd or a RawSocket.