ares_getnameinfo(3) [centos man page]
ARES_GETNAMEINFO(3) Library Functions Manual ARES_GETNAMEINFO(3) NAME
ares_getnameinfo - Address-to-nodename translation in protocol-independent manner SYNOPSIS
#include <ares.h> typedef void (*ares_nameinfo_callback)(void *arg, int status, int timeouts, char *node, char *service) void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, ares_socklen_t salen, int flags, ares_nameinfo_callback callback, void *arg) DESCRIPTION
The ares_getnameinfo function is defined for protocol-independent address translation. The function is a combination of ares_gethost- byaddr(3) and getservbyport(3). The function will translate the address either by executing a host query on the name service channel iden- tified by channel or it will attempt to resolve it locally if possible. The parameters sa and len give the address as a sockaddr struc- ture, and flags gives the options that the function will use. Valid flags are listed below: ARES_NI_NOFQDN Only the nodename portion of the FQDN is returned for local hosts. ARES_NI_NUMERICHOST The numeric form of the hostname is returned rather than the name. ARES_NI_NAMEREQD An error is returned if the hostname cannot be found in the DNS. ARES_NI_NUMERICSERV The numeric form of the service is returned rather than the name. ARES_NI_TCP The service name is to be looked up for the TCP protocol. ARES_NI_UDP The service name is to be looked up for the UDP protocol. ARES_NI_SCTP The service name is to be looked up for the SCTP protocol. ARES_NI_DCCP The service name is to be looked up for the DCCP protocol. ARES_NI_NUMERICSCOPE The numeric form of the scope ID is returned rather than the name. ARES_NI_LOOKUPHOST A hostname lookup is being requested. ARES_NI_LOOKUPSERVICE A service name lookup is being requested. When the query is complete or has failed, the ares library will invoke callback. Completion or failure of the query may happen immedi- ately, or may happen during a later call to ares_process(3), ares_destroy(3) or ares_cancel(3). The callback argument arg is copied from the ares_getnameinfo argument arg. The callback argument status indicates whether the query suc- ceeded and, if not, how it failed. It may have any of the following values: ARES_SUCCESS The host lookup completed successfully. ARES_ENOTIMP The ares library does not know how to look up addresses of type family. ARES_ENOTFOUND The address addr was not found. ARES_ENOMEM Memory was exhausted. ARES_ECANCELLED The query was cancelled. ARES_EDESTRUCTION The name service channel channel is being destroyed; the query will not be completed. ARES_EBADFLAGS The flags parameter contains an illegal value. The callback argument timeouts reports how many times a query timed out during the execution of the given request. On successful completion of the query, the callback argument node contains a string representing the hostname (assuming ARES_NI_LOOKUPHOST was specified). Additionally, service contains a string representing the service name (assuming ARES_NI_LOOKUPSERVICE was specified). If the query did not complete successfully, or one of the values was not requested, node or service will be NULL. SEE ALSO
ares_process(3), ares_getaddrinfo(3) AUTHOR
Dominick Meglio Copyright 2005 by Dominick Meglio. 1 May 2009 ARES_GETNAMEINFO(3)
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ARES_QUERY(3) Library Functions Manual ARES_QUERY(3) NAME
ares_query - Initiate a single-question DNS query SYNOPSIS
#include <ares.h> typedef void (*ares_callback)(void *arg, int status, int timeouts, unsigned char *abuf, int alen) void ares_query(ares_channel channel, const char *name, int dnsclass, int type, ares_callback callback, void *arg) DESCRIPTION
The ares_query function initiates a single-question DNS query on the name service channel identified by channel. The parameter name gives the query name as a NUL-terminated C string of period-separated labels optionally ending with a period; periods and backslashes within a label must be escaped with a backslash. The parameters dnsclass and type give the class and type of the query using the values defined in <arpa/nameser.h>. When the query is complete or has failed, the ares library will invoke callback. Completion or failure of the query may happen immediately, or may happen during a later call to ares_process(3) or ares_destroy(3). The callback argument arg is copied from the ares_query argument arg. The callback argument status indicates whether the query succeeded and, if not, how it failed. It may have any of the following values: ARES_SUCCESS The query completed successfully. ARES_ENODATA The query completed but contains no answers. ARES_EFORMERR The query completed but the server claims that the query was malformatted. ARES_ESERVFAIL The query completed but the server claims to have experienced a failure. (This code can only occur if the ARES_FLAG_NOCHECKRESP flag was specified at channel initialization time; otherwise, such responses are ignored at the ares_send(3) level.) ARES_ENOTFOUND The query completed but the queried-for domain name was not found. ARES_ENOTIMP The query completed but the server does not implement the operation requested by the query. (This code can only occur if the ARES_FLAG_NOCHECKRESP flag was specified at channel initialization time; otherwise, such responses are ignored at the ares_send(3) level.) ARES_EREFUSED The query completed but the server refused the query. (This code can only occur if the ARES_FLAG_NOCHECKRESP flag was specified at channel initialization time; otherwise, such responses are ignored at the ares_send(3) level.) ARES_EBADNAME The query name name could not be encoded as a domain name, either because it contained a zero-length label or because it contained a label of more than 63 characters. ARES_ETIMEOUT No name servers responded within the timeout period. ARES_ECONNREFUSED No name servers could be contacted. ARES_ENOMEM Memory was exhausted. ARES_EDESTRUCTION The name service channel channel is being destroyed; the query will not be completed. The callback argument timeouts reports how many times a query timed out during the execution of the given request. If the query completed (even if there was something wrong with it, as indicated by some of the above error codes), the callback argument abuf points to a result buffer of length alen. If the query did not complete, abuf will be NULL and alen will be 0. SEE ALSO
ares_process(3) AUTHOR
Greg Hudson, MIT Information Systems Copyright 1998 by the Massachusetts Institute of Technology. 24 July 1998 ARES_QUERY(3)