/contrib/bind9/lib/lwres/man/lwres_getipnode.3

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  1. .\" Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
  2. .\" Copyright (C) 2000, 2001, 2003 Internet Software Consortium.
  3. .\"
  4. .\" Permission to use, copy, modify, and/or distribute this software for any
  5. .\" purpose with or without fee is hereby granted, provided that the above
  6. .\" copyright notice and this permission notice appear in all copies.
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  8. .\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  9. .\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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  15. .\"
  16. .\" $Id$
  17. .\"
  18. .hy 0
  19. .ad l
  20. .\" Title: lwres_getipnode
  21. .\" Author:
  22. .\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
  23. .\" Date: Jun 30, 2000
  24. .\" Manual: BIND9
  25. .\" Source: BIND9
  26. .\"
  27. .TH "LWRES_GETIPNODE" "3" "Jun 30, 2000" "BIND9" "BIND9"
  28. .\" disable hyphenation
  29. .nh
  30. .\" disable justification (adjust text to left margin only)
  31. .ad l
  32. .SH "NAME"
  33. lwres_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent \- lightweight resolver nodename / address translation API
  34. .SH "SYNOPSIS"
  35. .nf
  36. #include <lwres/netdb.h>
  37. .fi
  38. .HP 39
  39. .BI "struct hostent * lwres_getipnodebyname(const\ char\ *" "name" ", int\ " "af" ", int\ " "flags" ", int\ *" "error_num" ");"
  40. .HP 39
  41. .BI "struct hostent * lwres_getipnodebyaddr(const\ void\ *" "src" ", size_t\ " "len" ", int\ " "af" ", int\ *" "error_num" ");"
  42. .HP 23
  43. .BI "void lwres_freehostent(struct\ hostent\ *" "he" ");"
  44. .SH "DESCRIPTION"
  45. .PP
  46. These functions perform thread safe, protocol independent nodename\-to\-address and address\-to\-nodename translation as defined in RFC2553.
  47. .PP
  48. They use a
  49. \fBstruct hostent\fR
  50. which is defined in
  51. \fInamedb.h\fR:
  52. .PP
  53. .RS 4
  54. .nf
  55. struct hostent {
  56. char *h_name; /* official name of host */
  57. char **h_aliases; /* alias list */
  58. int h_addrtype; /* host address type */
  59. int h_length; /* length of address */
  60. char **h_addr_list; /* list of addresses from name server */
  61. };
  62. #define h_addr h_addr_list[0] /* address, for backward compatibility */
  63. .fi
  64. .RE
  65. .sp
  66. .PP
  67. The members of this structure are:
  68. .PP
  69. \fBh_name\fR
  70. .RS 4
  71. The official (canonical) name of the host.
  72. .RE
  73. .PP
  74. \fBh_aliases\fR
  75. .RS 4
  76. A NULL\-terminated array of alternate names (nicknames) for the host.
  77. .RE
  78. .PP
  79. \fBh_addrtype\fR
  80. .RS 4
  81. The type of address being returned \- usually
  82. \fBPF_INET\fR
  83. or
  84. \fBPF_INET6\fR.
  85. .RE
  86. .PP
  87. \fBh_length\fR
  88. .RS 4
  89. The length of the address in bytes.
  90. .RE
  91. .PP
  92. \fBh_addr_list\fR
  93. .RS 4
  94. A
  95. \fBNULL\fR
  96. terminated array of network addresses for the host. Host addresses are returned in network byte order.
  97. .RE
  98. .PP
  99. \fBlwres_getipnodebyname()\fR
  100. looks up addresses of protocol family
  101. \fIaf\fR
  102. for the hostname
  103. \fIname\fR. The
  104. \fIflags\fR
  105. parameter contains ORed flag bits to specify the types of addresses that are searched for, and the types of addresses that are returned. The flag bits are:
  106. .PP
  107. \fBAI_V4MAPPED\fR
  108. .RS 4
  109. This is used with an
  110. \fIaf\fR
  111. of AF_INET6, and causes IPv4 addresses to be returned as IPv4\-mapped IPv6 addresses.
  112. .RE
  113. .PP
  114. \fBAI_ALL\fR
  115. .RS 4
  116. This is used with an
  117. \fIaf\fR
  118. of AF_INET6, and causes all known addresses (IPv6 and IPv4) to be returned. If AI_V4MAPPED is also set, the IPv4 addresses are return as mapped IPv6 addresses.
  119. .RE
  120. .PP
  121. \fBAI_ADDRCONFIG\fR
  122. .RS 4
  123. Only return an IPv6 or IPv4 address if here is an active network interface of that type. This is not currently implemented in the BIND 9 lightweight resolver, and the flag is ignored.
  124. .RE
  125. .PP
  126. \fBAI_DEFAULT\fR
  127. .RS 4
  128. This default sets the
  129. \fBAI_V4MAPPED\fR
  130. and
  131. \fBAI_ADDRCONFIG\fR
  132. flag bits.
  133. .RE
  134. .PP
  135. \fBlwres_getipnodebyaddr()\fR
  136. performs a reverse lookup of address
  137. \fIsrc\fR
  138. which is
  139. \fIlen\fR
  140. bytes long.
  141. \fIaf\fR
  142. denotes the protocol family, typically
  143. \fBPF_INET\fR
  144. or
  145. \fBPF_INET6\fR.
  146. .PP
  147. \fBlwres_freehostent()\fR
  148. releases all the memory associated with the
  149. \fBstruct hostent\fR
  150. pointer
  151. \fIhe\fR. Any memory allocated for the
  152. \fBh_name\fR,
  153. \fBh_addr_list\fR
  154. and
  155. \fBh_aliases\fR
  156. is freed, as is the memory for the
  157. \fBhostent\fR
  158. structure itself.
  159. .SH "RETURN VALUES"
  160. .PP
  161. If an error occurs,
  162. \fBlwres_getipnodebyname()\fR
  163. and
  164. \fBlwres_getipnodebyaddr()\fR
  165. set
  166. \fI*error_num\fR
  167. to an appropriate error code and the function returns a
  168. \fBNULL\fR
  169. pointer. The error codes and their meanings are defined in
  170. \fI<lwres/netdb.h>\fR:
  171. .PP
  172. \fBHOST_NOT_FOUND\fR
  173. .RS 4
  174. No such host is known.
  175. .RE
  176. .PP
  177. \fBNO_ADDRESS\fR
  178. .RS 4
  179. The server recognised the request and the name but no address is available. Another type of request to the name server for the domain might return an answer.
  180. .RE
  181. .PP
  182. \fBTRY_AGAIN\fR
  183. .RS 4
  184. A temporary and possibly transient error occurred, such as a failure of a server to respond. The request may succeed if retried.
  185. .RE
  186. .PP
  187. \fBNO_RECOVERY\fR
  188. .RS 4
  189. An unexpected failure occurred, and retrying the request is pointless.
  190. .RE
  191. .PP
  192. \fBlwres_hstrerror\fR(3)
  193. translates these error codes to suitable error messages.
  194. .SH "SEE ALSO"
  195. .PP
  196. \fBRFC2553\fR(),
  197. \fBlwres\fR(3),
  198. \fBlwres_gethostent\fR(3),
  199. \fBlwres_getaddrinfo\fR(3),
  200. \fBlwres_getnameinfo\fR(3),
  201. \fBlwres_hstrerror\fR(3).
  202. .SH "COPYRIGHT"
  203. Copyright \(co 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
  204. .br
  205. Copyright \(co 2000, 2001, 2003 Internet Software Consortium.
  206. .br