DOKK / manpages / debian 12 / libsocket-getaddrinfo-perl / Socket::GetAddrInfo::Emul.3pm.en
Socket::GetAddrInfo::Emul(3pm) User Contributed Perl Documentation Socket::GetAddrInfo::Emul(3pm)

"Socket::GetAddrInfo::Emul" - Pure Perl emulation of "getaddrinfo" and "getnameinfo" using IPv4-only legacy resolvers

"Socket::GetAddrInfo" attempts to provide the "getaddrinfo" and "getnameinfo" functions by some XS code that calls the real functions in libc. If for some reason this cannot be done; either there is no C compiler, or libc does not provide these functions, then they will be emulated using the legacy resolvers "gethostbyname", etc... These emulations are not a complete replacement of the real functions, because they only support IPv4 (the "AF_INET" socket family). In this case, the following restrictions will apply.

  • If the "family" hint is supplied, it must be "AF_INET". Any other value will result in an error thrown by "croak".
  • The only supported "flags" hint values are "AI_PASSIVE", "AI_CANONNAME", "AI_NUMERICSERV" and "AI_NUMERICHOST".

    The flags "AI_V4MAPPED" and "AI_ALL" are recognised but ignored, as they do not apply to "AF_INET" lookups. Since this function only returns "AF_INET" addresses, it does not need to probe the system for configured addresses in other families, so the "AI_ADDRCONFIG" flag is also ignored.

    Note that "AI_NUMERICSERV" is an extension not defined by RFC 2553, but is provided by most OSes. It is possible (though unlikely) that even the native XS implementation does not recognise this constant.

  • If the sockaddr family of $addr is anything other than "AF_INET", an error will be thrown with "croak".
  • The only supported $flags values are "NI_NUMERICHOST", "NI_NUMERICSERV", "NI_NOFQDN", "NI_NAMEREQD" and "NI_DGRAM".

This pure-perl emulation provides the IDN constants such as "AI_IDN" and "NI_IDN", but the "getaddrinfo" and "getnameinfo" functions will croak if passed these flags. This should allow a program to probe for their support, and fall back to some other behaviour instead.

Paul Evans <leonerd@leonerd.org.uk>

2022-10-13 perl v5.34.0