Dominick Meglio
20 years ago
parent
a6f7820033
commit
aba0b775ea
10 changed files with 1034 additions and 434 deletions
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.\" $Id$ |
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.\" |
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.\" Copyright 2005 by Dominick Meglio. |
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.\" |
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.\" Permission to use, copy, modify, and distribute this |
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.\" software and its documentation for any purpose and without |
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.\" fee is hereby granted, provided that the above copyright |
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.\" notice appear in all copies and that both that copyright |
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.\" notice and this permission notice appear in supporting |
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.\" documentation, and that the name of M.I.T. not be used in |
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.\" advertising or publicity pertaining to distribution of the |
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.\" software without specific, written prior permission. |
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.\" M.I.T. makes no representations about the suitability of |
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.\" this software for any purpose. It is provided "as is" |
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.\" without express or implied warranty. |
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.\" |
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.TH ARES_GETNAMEINFO 3 "16 May 2005" |
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.SH NAME |
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ares_getnameinfo \- Address-to-nodename translation in protocol-independent manner |
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.SH SYNOPSIS |
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.nf |
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.B #include <ares.h> |
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.PP |
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.B typedef void (*ares_nameinfo_callback)(void *\fIarg\fP, int \fIstatus\fP, |
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.B char *\fInode\fP, char *\fIservice\fP) |
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.PP |
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.B void ares_getnameinfo(ares_channel \fIchannel\fP, const struct sockaddr *\fIsa\fP, |
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.B socklen_t \fIsalen\fP, int \fIflags\fP, ares_nameinfo_callback \fIcallback\fP, |
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.B void *\fIarg\fP) |
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.fi |
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.SH DESCRIPTION |
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The |
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.B ares_getnameinfo |
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function is defined for protocol-independent address translation. The function |
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is a combination of \fIares_gethostbyaddr(3)\fP and \fIgetservbyport(3)\fP. The function will |
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translate the address either by executing a host query on the name service channel |
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identified by |
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.IR channel |
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or it will attempt to resolve it locally if possible. |
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The parameters |
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.I sa |
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and |
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.I len |
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give the address as a sockaddr structure, and |
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.I flags |
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gives the options that the function will use. Valid flags are listed below: |
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.TP 19 |
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.B ARES_NI_NOFQDN |
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Only the nodename portion of the FQDN is returned for local hosts. |
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.TP 19 |
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.B ARES_NI_NUMERICHOST |
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The numeric form of the hostname is returned rather than the name. |
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.TP 19 |
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.B ARES_NI_NAMEREQD |
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An error is returned if the hostname cannot be found in the DNS. |
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.TP 19 |
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.B ARES_NI_NUMERICSERV |
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The numeric form of the service is returned rather than the name. |
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.TP 19 |
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.B ARES_NI_TCP |
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The service name is to be looked up for the TCP protocol. |
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.TP 19 |
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.B ARES_NI_UDP |
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The service name is to be looked up for the UDP protocol. |
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.TP 19 |
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.B ARES_NI_SCTP |
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The service name is to be looked up for the SCTP protocol. |
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.TP 19 |
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.B ARES_NI_DCCP |
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The service name is to be looked up for the DCCP protocol. |
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.TP 19 |
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.B ARES_NI_NUMERICSCOPE |
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The numeric form of the scope ID is returned rather than the name. |
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.TP 19 |
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.B ARES_NI_LOOKUPHOST |
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A hostname lookup is being requested. |
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.TP 19 |
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.B ARES_NI_LOOKUPSERVICE |
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A service name lookup is being requested. |
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.PP |
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When the query |
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is complete or has |
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failed, the ares library will invoke \fIcallback\fP. Completion or failure of |
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the query may happen immediately, or may happen during a later call to |
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\fIares_process(3)\fP, \fIares_destroy(3)\fP or \fIares_cancel(3)\fP. |
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.PP |
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The callback argument |
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.I arg |
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is copied from the |
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.B ares_getnameinfo |
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argument |
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.IR arg . |
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The callback argument |
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.I status |
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indicates whether the query succeeded and, if not, how it failed. It |
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may have any of the following values: |
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.TP 19 |
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.B ARES_SUCCESS |
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The host lookup completed successfully. |
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.TP 19 |
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.B ARES_ENOTIMP |
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The ares library does not know how to look up addresses of type |
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.IR family . |
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.TP 19 |
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.B ARES_ENOTFOUND |
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The address |
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.I addr |
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was not found. |
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.TP 19 |
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.B ARES_ENOMEM |
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Memory was exhausted. |
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.TP 19 |
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.B ARES_EDESTRUCTION |
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The name service channel |
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.I channel |
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is being destroyed; the query will not be completed. |
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.TP 19 |
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.B ARES_EBADFLAGS |
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The |
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.I flags |
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parameter contains an illegal value. |
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.PP |
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On successful completion of the query, the callback argument |
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.I node |
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contains a string representing the hostname (assuming |
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.B ARES_NI_LOOKUPHOST |
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was specified). Additionally, |
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.I service |
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contains a string representing the service name (assuming |
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.B ARES_NI_LOOKUPSERVICE |
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was specified). |
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If the query did not complete successfully, or one of the values |
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was not requested, |
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.I node |
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or |
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.I service |
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will be |
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.BR NULL . |
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.SH SEE ALSO |
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.BR ares_process (3), |
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.BR ares_getaddrinfo (3) |
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.SH AUTHOR |
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Dominick Meglio |
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.br |
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Copyright 2005 by Dominick Meglio. |
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@ -0,0 +1,322 @@ |
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/* Copyright 2005 by Dominick Meglio
|
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* |
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* Permission to use, copy, modify, and distribute this |
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* software and its documentation for any purpose and without |
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* fee is hereby granted, provided that the above copyright |
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* notice appear in all copies and that both that copyright |
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* notice and this permission notice appear in supporting |
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* documentation, and that the name of M.I.T. not be used in |
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* advertising or publicity pertaining to distribution of the |
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* software without specific, written prior permission. |
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* M.I.T. makes no representations about the suitability of |
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* this software for any purpose. It is provided "as is" |
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* without express or implied warranty. |
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*/ |
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#include "setup.h" |
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#include <sys/types.h> |
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|
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#if defined(WIN32) && !defined(WATT32) |
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#include "nameser.h" |
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#else |
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#include <sys/socket.h> |
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#include <netinet/in.h> |
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#include <netdb.h> |
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#include <arpa/nameser.h> |
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#ifdef HAVE_ARPA_NAMESER_COMPAT_H |
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#include <arpa/nameser_compat.h> |
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#endif |
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#endif |
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|
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#ifdef HAVE_NET_IF_H |
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#include <net/if.h> |
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#endif |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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|
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#include "ares.h" |
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#include "ares_private.h" |
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#include "ares_ipv6.h" |
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#include "inet_ntop.h" |
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|
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#ifdef WATT32 |
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#undef WIN32 |
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#endif |
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|
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struct nameinfo_query { |
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ares_nameinfo_callback callback; |
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void *arg; |
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union { |
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struct sockaddr_in addr4; |
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struct sockaddr_in6 addr6; |
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} addr; |
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int family; |
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int flags; |
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}; |
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|
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#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID |
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#define IPBUFSIZ 40+IF_NAMESIZE |
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#else |
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#define IPBUFSIZ 40 |
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#endif |
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|
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static void nameinfo_callback(void *arg, int status, struct hostent *host); |
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static char *lookup_service(unsigned short port, int flags, char *buf); |
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static char *append_scopeid(struct sockaddr_in6 *addr6, unsigned int scopeid, char *buf); |
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static char *ares_striendstr(const char *s1, const char *s2); |
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|
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void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, socklen_t salen, |
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int flags, ares_nameinfo_callback callback, void *arg) |
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{ |
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struct sockaddr_in *addr; |
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struct sockaddr_in6 *addr6; |
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struct nameinfo_query *niquery; |
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|
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/* Verify the buffer size */ |
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if (salen == sizeof(struct sockaddr_in)) |
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addr = (struct sockaddr_in *)sa; |
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else if (salen == sizeof(struct sockaddr_in6)) |
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addr6 = (struct sockaddr_in6 *)sa; |
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else |
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{ |
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callback(arg, ARES_ENOTIMP, NULL, NULL); |
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return; |
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} |
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|
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/* If neither, assume they want a host */ |
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if (!(flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST)) |
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flags |= ARES_NI_LOOKUPHOST; |
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|
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/* All they want is a service, no need for DNS */ |
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if ((flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST)) |
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{ |
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char buf[33], *service; |
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unsigned int port = 0; |
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if (salen == sizeof(struct sockaddr_in)) |
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port = addr->sin_port; |
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else |
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port = addr6->sin6_port; |
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service = lookup_service(port, flags, buf); |
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callback(arg, ARES_SUCCESS, NULL, service); |
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return; |
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} |
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|
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/* They want a host lookup */ |
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if ((flags & ARES_NI_LOOKUPHOST)) |
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{ |
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/* A numeric host can be handled without DNS */ |
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if ((flags & ARES_NI_NUMERICHOST)) |
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{ |
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unsigned int port = 0; |
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char ipbuf[IPBUFSIZ]; |
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char srvbuf[32]; |
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char *service = NULL; |
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ipbuf[0] = 0; |
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|
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/* Specifying not to lookup a host, but then saying a host
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* is required has to be illegal. |
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*/ |
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if (flags & ARES_NI_NAMEREQD) |
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{ |
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callback(arg, ARES_EBADFLAGS, NULL, NULL); |
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return; |
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} |
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if (salen == sizeof(struct sockaddr_in6)) |
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{ |
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ares_inet_ntop(AF_INET6, &addr6->sin6_addr, ipbuf, IPBUFSIZ); |
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port = addr6->sin6_port; |
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/* If the system supports scope IDs, use it */ |
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#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID |
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append_scopeid(addr6, flags, ipbuf); |
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#endif |
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} |
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else |
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{ |
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ares_inet_ntop(AF_INET, &addr->sin_addr, ipbuf, IPBUFSIZ); |
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port = addr->sin_port; |
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} |
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/* They also want a service */ |
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if (flags & ARES_NI_LOOKUPSERVICE) |
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service = lookup_service(port, flags, srvbuf); |
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callback(arg, ARES_SUCCESS, ipbuf, service); |
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return; |
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} |
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/* This is where a DNS lookup becomes necessary */ |
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else |
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{ |
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niquery = malloc(sizeof(struct nameinfo_query)); |
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if (!niquery) |
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{ |
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callback(arg, ARES_ENOMEM, NULL, NULL); |
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return; |
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} |
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niquery->callback = callback; |
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niquery->arg = arg; |
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niquery->flags = flags; |
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if (sa->sa_family == AF_INET)
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{ |
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niquery->family = AF_INET; |
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memcpy(&niquery->addr.addr4, addr, sizeof(addr)); |
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ares_gethostbyaddr(channel, &addr->sin_addr, sizeof(struct in_addr), AF_INET,
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nameinfo_callback, niquery); |
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} |
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else |
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{ |
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niquery->family = AF_INET6; |
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memcpy(&niquery->addr.addr6, addr6, sizeof(addr6)); |
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ares_gethostbyaddr(channel, &addr6->sin6_addr, sizeof(struct in6_addr), AF_INET6,
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nameinfo_callback, niquery); |
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} |
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} |
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} |
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} |
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|
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static void nameinfo_callback(void *arg, int status, struct hostent *host) |
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{ |
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struct nameinfo_query *niquery = (struct nameinfo_query *) arg; |
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char srvbuf[33]; |
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char *service = NULL; |
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if (status == ARES_SUCCESS) |
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{ |
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/* They want a service too */ |
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if (niquery->flags & ARES_NI_LOOKUPSERVICE) |
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{ |
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if (niquery->family == AF_INET) |
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service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags, srvbuf); |
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else |
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service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags, srvbuf); |
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} |
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/* NOFQDN means we have to strip off the domain name portion.
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We do this by determining our own domain name, then searching the string |
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for this domain name and removing it. |
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*/ |
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if (niquery->flags & ARES_NI_NOFQDN) |
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{ |
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char buf[255]; |
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char *domain; |
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gethostname(buf, 255); |
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if ((domain = strchr(buf, '.'))) |
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{ |
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char *end = ares_striendstr(host->h_name, domain); |
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if (end) |
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*end = 0; |
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}
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} |
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callback(niquery->arg, ARES_SUCCESS, host->h_name, service); |
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return; |
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} |
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/* We couldn't find the host, but it's OK, we can use the IP */ |
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else if (status == ARES_ENOTFOUND && !(niquery->flags & ARES_NI_NAMEREQD)) |
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{ |
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char ipbuf[IPBUFSIZ]; |
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if (niquery->family == AF_INET) |
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ares_inet_ntop(AF_INET, &niquery->addr.addr4.sin_addr, ipbuf, IPBUFSIZ); |
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else |
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{ |
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ares_inet_ntop(AF_INET6, &niquery->addr.addr6.sin6_addr, ipbuf, IPBUFSIZ); |
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#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID |
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append_scopeid(&niquery->addr.addr6, niquery->flags, ipbuf); |
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#endif |
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} |
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/* They want a service too */ |
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if (niquery->flags & ARES_NI_LOOKUPSERVICE) |
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{ |
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if (niquery->family == AF_INET) |
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service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags, srvbuf); |
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else |
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service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags, srvbuf); |
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} |
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callback(niquery->arg, ARES_SUCCESS, ipbuf, service); |
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return; |
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} |
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callback(niquery->arg, status, NULL, NULL); |
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free(niquery); |
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} |
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static char *lookup_service(unsigned short port, int flags, char *buf) |
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{ |
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if (port) |
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{ |
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/* Just return the port as a string */ |
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if (flags & ARES_NI_NUMERICSERV) |
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sprintf(buf, "%u", ntohs(port)); |
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else |
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{ |
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struct servent *se; |
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char *proto; |
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if (flags & ARES_NI_UDP) |
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proto = "udp"; |
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else if (flags & ARES_NI_SCTP) |
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proto = "sctp"; |
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else if (flags & ARES_NI_DCCP) |
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proto = "dccp"; |
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else |
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proto = "tcp"; |
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se = getservbyport(port, proto); |
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if (se && se->s_name) |
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strcpy(buf, se->s_name); |
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else |
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sprintf(buf, "%u", ntohs(port)); |
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} |
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return buf; |
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} |
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return NULL; |
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} |
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#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID |
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static char *append_scopeid(struct sockaddr_in6 *addr6, unsigned int flags, char *buf) |
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{ |
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char tmpbuf[IF_NAMESIZE + 1]; |
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tmpbuf[0] = '%'; |
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#ifdef HAVE_IF_INDEXTONAME |
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if ((flags & ARES_NI_NUMERICSCOPE) || (!IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr) |
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&& !IN6_IS_ADDR_MC_LINKLOCAL(&addr6->sin6_addr))) |
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{ |
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sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id); |
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} |
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else |
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{ |
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if (if_indextoname(addr6->sin6_scope_id, &tmpbuf[1]) == NULL) |
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sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id); |
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} |
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#else |
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sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id); |
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#endif |
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strcat(buf, tmpbuf); |
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return buf; |
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} |
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#endif |
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/* Determines if s1 ends with the string in s2 (case-insensitive) */ |
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static char *ares_striendstr(const char *s1, const char *s2) |
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{ |
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const char *c1, *c2, *c1_begin; |
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size_t s1_len = strlen(s1), s2_len = strlen(s2); |
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/* If the substr is longer than the full str, it can't match */ |
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if (s2_len > s1_len) |
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return NULL; |
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/* Jump to the end of s1 minus the length of s2 */ |
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c1 = (const char *)c1_begin = s1+s1_len-s2_len; |
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c2 = s2; |
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while (c2 < s2+s2_len) |
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{ |
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if (tolower(*c1) != tolower(*c2)) |
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return NULL; |
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else |
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{ |
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c1++; |
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c2++; |
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} |
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} |
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if (c2 == c1 == NULL) |
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return c1_begin; |
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return NULL; |
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} |
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