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a60fb26
(Get the code!)
To clarify what's wrong: it was a common historic misunderstanding that "canonical" name meant reverse DNS lookups. This was a cause of bad lookup performance in applications that were using AI_CANNONNAME correctly and not respecting it to perform PTR lookups. For a reference on why the PTR lookup is incorrect, see the following paragraphs in POSIX:
From DESCRIPTION of getaddrinfo:
"If the AI_CANONNAME flag is specified and the nodename argument is not null, the function shall attempt to determine the canonical name corresponding to nodename (for example, if nodename is an alias or shorthand notation for a complete name).
Note:
Since different implementations use different conceptual models, the terms ``canonical name'' and ``alias'' cannot be precisely defined for the general case. However, Domain Name System implementations are expected to interpret them as they are used in RFC 1034.
A numeric host address string is not a ``name'', and thus does not have a ``canonical name'' form; no address to host name translation is performed. See below for handling of the case where a canonical name cannot be obtained."
And from APPLICATION USAGE:
"The term ``canonical name'' is misleading; it is taken from the Domain Name System (RFC 2181). It should be noted that the canonical name is a result of alias processing, and not necessarily a unique attribute of a host, address, or set of addresses. See RFC 2181 for more discussion of this in the Domain Name System context."
Source: http://