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

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  1. .\" Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
  2. .\" Copyright (C) 2000, 2001 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
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  15. .\"
  16. .\" $Id$
  17. .\"
  18. .hy 0
  19. .ad l
  20. .\" Title: lwres_noop
  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_NOOP" "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_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free \- lightweight resolver no\-op message handling
  34. .SH "SYNOPSIS"
  35. .nf
  36. #include <lwres/lwres.h>
  37. .fi
  38. .HP 40
  39. .BI "lwres_result_t lwres_nooprequest_render(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
  40. .HP 41
  41. .BI "lwres_result_t lwres_noopresponse_render(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
  42. .HP 39
  43. .BI "lwres_result_t lwres_nooprequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_nooprequest_t\ **" "structp" ");"
  44. .HP 40
  45. .BI "lwres_result_t lwres_noopresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_noopresponse_t\ **" "structp" ");"
  46. .HP 29
  47. .BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
  48. .HP 28
  49. .BI "void lwres_nooprequest_free(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ **" "structp" ");"
  50. .SH "DESCRIPTION"
  51. .PP
  52. These are low\-level routines for creating and parsing lightweight resolver no\-op request and response messages.
  53. .PP
  54. The no\-op message is analogous to a
  55. \fBping\fR
  56. packet: a packet is sent to the resolver daemon and is simply echoed back. The opcode is intended to allow a client to determine if the server is operational or not.
  57. .PP
  58. There are four main functions for the no\-op opcode. One render function converts a no\-op request structure \(em
  59. \fBlwres_nooprequest_t\fR
  60. \(em to the lighweight resolver's canonical format. It is complemented by a parse function that converts a packet in this canonical format to a no\-op request structure. Another render function converts the no\-op response structure \(em
  61. \fBlwres_noopresponse_t\fR
  62. to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a no\-op response structure.
  63. .PP
  64. These structures are defined in
  65. \fIlwres/lwres.h\fR. They are shown below.
  66. .PP
  67. .RS 4
  68. .nf
  69. #define LWRES_OPCODE_NOOP 0x00000000U
  70. .fi
  71. .RE
  72. .sp
  73. .PP
  74. .RS 4
  75. .nf
  76. typedef struct {
  77. lwres_uint16_t datalength;
  78. unsigned char *data;
  79. } lwres_nooprequest_t;
  80. .fi
  81. .RE
  82. .sp
  83. .PP
  84. .RS 4
  85. .nf
  86. typedef struct {
  87. lwres_uint16_t datalength;
  88. unsigned char *data;
  89. } lwres_noopresponse_t;
  90. .fi
  91. .RE
  92. .sp
  93. .PP
  94. Although the structures have different types, they are identical. This is because the no\-op opcode simply echos whatever data was sent: the response is therefore identical to the request.
  95. .PP
  96. \fBlwres_nooprequest_render()\fR
  97. uses resolver context
  98. \fIctx\fR
  99. to convert no\-op request structure
  100. \fIreq\fR
  101. to canonical format. The packet header structure
  102. \fIpkt\fR
  103. is initialised and transferred to buffer
  104. \fIb\fR. The contents of
  105. \fI*req\fR
  106. are then appended to the buffer in canonical format.
  107. \fBlwres_noopresponse_render()\fR
  108. performs the same task, except it converts a no\-op response structure
  109. \fBlwres_noopresponse_t\fR
  110. to the lightweight resolver's canonical format.
  111. .PP
  112. \fBlwres_nooprequest_parse()\fR
  113. uses context
  114. \fIctx\fR
  115. to convert the contents of packet
  116. \fIpkt\fR
  117. to a
  118. \fBlwres_nooprequest_t\fR
  119. structure. Buffer
  120. \fIb\fR
  121. provides space to be used for storing this structure. When the function succeeds, the resulting
  122. \fBlwres_nooprequest_t\fR
  123. is made available through
  124. \fI*structp\fR.
  125. \fBlwres_noopresponse_parse()\fR
  126. offers the same semantics as
  127. \fBlwres_nooprequest_parse()\fR
  128. except it yields a
  129. \fBlwres_noopresponse_t\fR
  130. structure.
  131. .PP
  132. \fBlwres_noopresponse_free()\fR
  133. and
  134. \fBlwres_nooprequest_free()\fR
  135. release the memory in resolver context
  136. \fIctx\fR
  137. that was allocated to the
  138. \fBlwres_noopresponse_t\fR
  139. or
  140. \fBlwres_nooprequest_t\fR
  141. structures referenced via
  142. \fIstructp\fR.
  143. .SH "RETURN VALUES"
  144. .PP
  145. The no\-op opcode functions
  146. \fBlwres_nooprequest_render()\fR,
  147. \fBlwres_noopresponse_render()\fR
  148. \fBlwres_nooprequest_parse()\fR
  149. and
  150. \fBlwres_noopresponse_parse()\fR
  151. all return
  152. \fBLWRES_R_SUCCESS\fR
  153. on success. They return
  154. \fBLWRES_R_NOMEMORY\fR
  155. if memory allocation fails.
  156. \fBLWRES_R_UNEXPECTEDEND\fR
  157. is returned if the available space in the buffer
  158. \fIb\fR
  159. is too small to accommodate the packet header or the
  160. \fBlwres_nooprequest_t\fR
  161. and
  162. \fBlwres_noopresponse_t\fR
  163. structures.
  164. \fBlwres_nooprequest_parse()\fR
  165. and
  166. \fBlwres_noopresponse_parse()\fR
  167. will return
  168. \fBLWRES_R_UNEXPECTEDEND\fR
  169. if the buffer is not empty after decoding the received packet. These functions will return
  170. \fBLWRES_R_FAILURE\fR
  171. if
  172. \fBpktflags\fR
  173. in the packet header structure
  174. \fBlwres_lwpacket_t\fR
  175. indicate that the packet is not a response to an earlier query.
  176. .SH "SEE ALSO"
  177. .PP
  178. \fBlwres_packet\fR(3)
  179. .SH "COPYRIGHT"
  180. Copyright \(co 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
  181. .br
  182. Copyright \(co 2000, 2001 Internet Software Consortium.
  183. .br