1ARES_GETHOSTBYNAME(3) Library Functions Manual ARES_GETHOSTBYNAME(3)
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6 ares_gethostbyname - Initiate a host query by name
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9 #include <ares.h>
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11 typedef void (*ares_host_callback)(void *arg, int status,
12 int timeouts, struct hostent *hostent)
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14 void ares_gethostbyname(ares_channel channel, const char *name,
15 int family, ares_host_callback callback, void *arg)
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18 The ares_gethostbyname function initiates a host query by name on the
19 name service channel identified by channel. The parameter name gives
20 the hostname as a NUL-terminated C string, and family gives the desired
21 type of address for the resulting host entry. When the query is com‐
22 plete or has failed, the ares library will invoke callback. Completion
23 or failure of the query may happen immediately, or may happen during a
24 later call to ares_process(3), ares_destroy(3) or ares_cancel(3).
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26 The callback argument arg is copied from the ares_gethostbyname argu‐
27 ment arg. The callback argument status indicates whether the query
28 succeeded and, if not, how it failed. It may have any of the following
29 values:
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31 ARES_SUCCESS The host lookup completed successfully.
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33 ARES_ENOTIMP The ares library does not know how to find addresses
34 of type family.
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36 ARES_EBADNAME The hostname name is composed entirely of numbers
37 and periods, but is not a valid representation of an
38 Internet address.
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40 ARES_ENODATA There was no data returned to extract a result from.
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42 ARES_ENOTFOUND The name name was not found.
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44 ARES_ENOMEM Memory was exhausted.
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46 ARES_ECANCELLED The query was cancelled.
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48 ARES_EDESTRUCTION The name service channel channel is being destroyed;
49 the query will not be completed.
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51 The callback argument timeouts reports how many times a query timed out
52 during the execution of the given request.
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54 On successful completion of the query, the callback argument hostent
55 points to a struct hostent containing the name of the host returned by
56 the query. The callback need not and should not attempt to free the
57 memory pointed to by hostent; the ares library will free it when the
58 callback returns. If the query did not complete successfully, hostent
59 will be NULL.
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62 ares_process(3), ares_gethostbyaddr(3)
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65 Greg Hudson, MIT Information Systems
66 Copyright 1998 by the Massachusetts Institute of Technology.
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70 25 July 1998 ARES_GETHOSTBYNAME(3)