1LWRES_GABN(3) BIND9 LWRES_GABN(3)
2
6 lwres_gabnrequest_render, lwres_gabnresponse_render,
7 lwres_gabnrequest_parse, lwres_gabnresponse_parse,
8 lwres_gabnresponse_free, lwres_gabnrequest_free - lightweight resolver
9 getaddrbyname message handling
10
12 #include <lwres/lwres.h>
13 lwres_result_t lwres_gabnrequest_render(lwres_context_t *ctx,
15 lwres_gabnrequest_t *req,
16 lwres_lwpacket_t *pkt,
17 lwres_buffer_t *b);
18 lwres_result_t lwres_gabnresponse_render(lwres_context_t *ctx,
20 lwres_gabnresponse_t *req,
21 lwres_lwpacket_t *pkt,
22 lwres_buffer_t *b);
23 lwres_result_t lwres_gabnrequest_parse(lwres_context_t *ctx,
25 lwres_buffer_t *b,
26 lwres_lwpacket_t *pkt,
27 lwres_gabnrequest_t **structp);
28 lwres_result_t lwres_gabnresponse_parse(lwres_context_t *ctx,
30 lwres_buffer_t *b,
31 lwres_lwpacket_t *pkt,
32 lwres_gabnresponse_t **structp);
33 void lwres_gabnresponse_free(lwres_context_t *ctx,
35 lwres_gabnresponse_t **structp);
36 void lwres_gabnrequest_free(lwres_context_t *ctx,
38 lwres_gabnrequest_t **structp);
39
41 These are low-level routines for creating and parsing lightweight
42 resolver name-to-address lookup request and response messages.
43 There are four main functions for the getaddrbyname opcode. One render
45 function converts a getaddrbyname request structure —
46 lwres_gabnrequest_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 getaddrbyname request structure. Another render
49 function converts the getaddrbyname response structure —
50 lwres_gabnresponse_t — to the canonical format. This is complemented by
51 a parse function which converts a packet in canonical format to a
52 getaddrbyname response structure.
53 These structures are defined in <lwres/lwres.h>. They are shown below.
55 #define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U
57 typedef struct lwres_addr lwres_addr_t;
59 typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
60 typedef struct {
62 uint32_t flags;
63 uint32_t addrtypes;
64 uint16_t namelen;
65 char *name;
66 } lwres_gabnrequest_t;
67 typedef struct {
69 uint32_t flags;
70 uint16_t naliases;
71 uint16_t naddrs;
72 char *realname;
73 char **aliases;
74 uint16_t realnamelen;
75 uint16_t *aliaslen;
76 lwres_addrlist_t addrs;
77 void *base;
78 size_t baselen;
79 } lwres_gabnresponse_t;
80 lwres_gabnrequest_render() uses resolver context ctx to convert
82 getaddrbyname request structure req to canonical format. The packet
83 header structure pkt is initialised and transferred to buffer b. The
84 contents of *req are then appended to the buffer in canonical format.
85 lwres_gabnresponse_render() performs the same task, except it converts
86 a getaddrbyname response structure lwres_gabnresponse_t to the
87 lightweight resolver's canonical format.
88 lwres_gabnrequest_parse() uses context ctx to convert the contents of
90 packet pkt to a lwres_gabnrequest_t structure. Buffer b provides space
91 to be used for storing this structure. When the function succeeds, the
92 resulting lwres_gabnrequest_t is made available through *structp.
93 lwres_gabnresponse_parse() offers the same semantics as
94 lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t
95 structure.
96 lwres_gabnresponse_free() and lwres_gabnrequest_free() release the
98 memory in resolver context ctx that was allocated to the
99 lwres_gabnresponse_t or lwres_gabnrequest_t structures referenced via
100 structp. Any memory associated with ancillary buffers and strings for
101 those structures is also discarded.
102
104 The getaddrbyname opcode functions lwres_gabnrequest_render(),
105 lwres_gabnresponse_render() lwres_gabnrequest_parse() and
106 lwres_gabnresponse_parse() all return LWRES_R_SUCCESS on success. They
107 return LWRES_R_NOMEMORY if memory allocation fails.
108 LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
109 b is too small to accommodate the packet header or the
110 lwres_gabnrequest_t and lwres_gabnresponse_t structures.
111 lwres_gabnrequest_parse() and lwres_gabnresponse_parse() will return
112 LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
113 received packet. These functions will return LWRES_R_FAILURE if
114 pktflags in the packet header structure lwres_lwpacket_t indicate that
115 the packet is not a response to an earlier query.
116
118 lwres_packet(3)
119
121 Internet Systems Consortium, Inc.
122
124 Copyright © 2000, 2001, 2004, 2005, 2007, 2014-2016, 2018-2021 Internet
125 Systems Consortium, Inc. ("ISC")
126ISC 2007-06-18 LWRES_GABN(3)