1LWRES_GNBA(3) BIND9 LWRES_GNBA(3)
2
6 lwres_gnbarequest_render, lwres_gnbaresponse_render,
7 lwres_gnbarequest_parse, lwres_gnbaresponse_parse,
8 lwres_gnbaresponse_free, lwres_gnbarequest_free - lightweight resolver
9 getnamebyaddress message handling
10
12 #include <lwres/lwres.h>
13 lwres_result_t lwres_gnbarequest_render(lwres_context_t *ctx,
15 lwres_gnbarequest_t *req,
16 lwres_lwpacket_t *pkt,
17 lwres_buffer_t *b);
18 lwres_result_t lwres_gnbaresponse_render(lwres_context_t *ctx,
20 lwres_gnbaresponse_t *req,
21 lwres_lwpacket_t *pkt,
22 lwres_buffer_t *b);
23 lwres_result_t lwres_gnbarequest_parse(lwres_context_t *ctx,
25 lwres_buffer_t *b,
26 lwres_lwpacket_t *pkt,
27 lwres_gnbarequest_t **structp);
28 lwres_result_t lwres_gnbaresponse_parse(lwres_context_t *ctx,
30 lwres_buffer_t *b,
31 lwres_lwpacket_t *pkt,
32 lwres_gnbaresponse_t **structp);
33 void lwres_gnbaresponse_free(lwres_context_t *ctx,
35 lwres_gnbaresponse_t **structp);
36 void lwres_gnbarequest_free(lwres_context_t *ctx,
38 lwres_gnbarequest_t **structp);
39
41 These are low-level routines for creating and parsing lightweight
42 resolver address-to-name lookup request and response messages.
43 There are four main functions for the getnamebyaddr opcode. One render
45 function converts a getnamebyaddr request structure —
46 lwres_gnbarequest_t — to the lightweight resolver's canonical format.
47 It is complemented by a parse function that converts a packet in this
48 canonical format to a getnamebyaddr request structure. Another render
49 function converts the getnamebyaddr response structure —
50 lwres_gnbaresponse_t to the canonical format. This is complemented by a
51 parse function which converts a packet in canonical format to a
52 getnamebyaddr response structure.
53 These structures are defined in lwres/lwres.h. They are shown below.
55 #define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U
57 typedef struct {
60 lwres_uint32_t flags;
61 lwres_addr_t addr;
62 } lwres_gnbarequest_t;
63 typedef struct {
66 lwres_uint32_t flags;
67 lwres_uint16_t naliases;
68 char *realname;
69 char **aliases;
70 lwres_uint16_t realnamelen;
71 lwres_uint16_t *aliaslen;
72 void *base;
73 size_t baselen;
74 } lwres_gnbaresponse_t;
75 lwres_gnbarequest_render() uses resolver context ctx to convert
78 getnamebyaddr request structure req to canonical format. The packet
79 header structure pkt is initialised and transferred to buffer b. The
80 contents of *req are then appended to the buffer in canonical format.
81 lwres_gnbaresponse_render() performs the same task, except it converts
82 a getnamebyaddr response structure lwres_gnbaresponse_t to the
83 lightweight resolver's canonical format.
84 lwres_gnbarequest_parse() uses context ctx to convert the contents of
86 packet pkt to a lwres_gnbarequest_t structure. Buffer b provides space
87 to be used for storing this structure. When the function succeeds, the
88 resulting lwres_gnbarequest_t is made available through *structp.
89 lwres_gnbaresponse_parse() offers the same semantics as
90 lwres_gnbarequest_parse() except it yields a lwres_gnbaresponse_t
91 structure.
92 lwres_gnbaresponse_free() and lwres_gnbarequest_free() release the
94 memory in resolver context ctx that was allocated to the
95 lwres_gnbaresponse_t or lwres_gnbarequest_t structures referenced via
96 structp. Any memory associated with ancillary buffers and strings for
97 those structures is also discarded.
98
100 The getnamebyaddr opcode functions lwres_gnbarequest_render(),
101 lwres_gnbaresponse_render() lwres_gnbarequest_parse() and
102 lwres_gnbaresponse_parse() all return LWRES_R_SUCCESS on success. They
103 return LWRES_R_NOMEMORY if memory allocation fails.
104 LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
105 b is too small to accommodate the packet header or the
106 lwres_gnbarequest_t and lwres_gnbaresponse_t structures.
107 lwres_gnbarequest_parse() and lwres_gnbaresponse_parse() will return
108 LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
109 received packet. These functions will return LWRES_R_FAILURE if
110 pktflags in the packet header structure lwres_lwpacket_t indicate that
111 the packet is not a response to an earlier query.
112
114 lwres_packet(3).
115
117 Copyright © 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
118 Copyright © 2000, 2001 Internet Software Consortium.
119BIND9 Jun 30, 2000 LWRES_GNBA(3)