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ares_process(3) [centos man page]

ARES_PROCESS(3) 					     Library Functions Manual						   ARES_PROCESS(3)

ares_process - Process events for name resolution SYNOPSIS
#include <ares.h> void ares_process(ares_channel channel, fd_set *read_fds, fd_set *write_fds) void ares_process_fd(ares_channel channel, ares_socket_t read_fd, ares_socket_t write_fd) DESCRIPTION
The ares_process(3) function handles input/output events and timeouts associated with queries pending on the name service channel identi- fied by channel. The file descriptor sets pointed to by read_fds and write_fds should have file descriptors set in them according to whether the file descriptors specified by ares_fds(3) are ready for reading and writing. (The easiest way to determine this information is to invoke select with a timeout no greater than the timeout given by ares_timeout(3) ). The ares_process function will invoke callbacks for pending queries if they complete successfully or fail. ares_process_fd(3) works the same way but acts and operates only on the specific file descriptors (sockets) you pass in to the function. Use ARES_SOCKET_BAD for "no action". This function is of course provided to allow users of c-ares to void select() in their applications and within c-ares. EXAMPLE The following code fragment waits for all pending queries on a channel to complete: int nfds, count; fd_set readers, writers; struct timeval tv, *tvp; while (1) { FD_ZERO(&readers); FD_ZERO(&writers); nfds = ares_fds(channel, &readers, &writers); if (nfds == 0) break; tvp = ares_timeout(channel, NULL, &tv); count = select(nfds, &readers, &writers, NULL, tvp); ares_process(channel, &readers, &writers); } SEE ALSO
ares_fds(3), ares_timeout(3) AUTHOR
Greg Hudson, MIT Information Systems Copyright 1998 by the Massachusetts Institute of Technology. 25 July 1998 ARES_PROCESS(3)

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ARES_GETHOSTBYADDR(3)					     Library Functions Manual					     ARES_GETHOSTBYADDR(3)

ares_gethostbyaddr - Initiate a host query by address SYNOPSIS
#include <ares.h> typedef void (*ares_host_callback)(void *arg, int status, int timeouts, struct hostent *hostent) void ares_gethostbyaddr(ares_channel channel, const void *addr, int addrlen, int family, ares_host_callback callback, void *arg) DESCRIPTION
The ares_gethostbyaddr function initiates a host query by address on the name service channel identified by channel. The parameters addr and addrlen give the address as a series of bytes, and family gives the type of address. 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), ares_destroy(3) or ares_cancel(3). The callback argument arg is copied from the ares_gethostbyaddr 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 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. 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 hostent points to a struct hostent containing the name of the host returned by the query. The callback need not and should not attempt to free the memory pointed to by hostent; the ares library will free it when the callback returns. If the query did not complete successfully, hostent will be NULL. SEE ALSO
ares_process(3), ares_gethostbyname(3) AUTHOR
Greg Hudson, MIT Information Systems Copyright 1998 by the Massachusetts Institute of Technology. 24 July 1998 ARES_GETHOSTBYADDR(3)
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