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 lighweight resolver's canonical format. It
47 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;
60 typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
61 typedef struct {
64 lwres_uint32_t flags;
65 lwres_uint32_t addrtypes;
66 lwres_uint16_t namelen;
67 char *name;
68 } lwres_gabnrequest_t;
69 typedef struct {
72 lwres_uint32_t flags;
73 lwres_uint16_t naliases;
74 lwres_uint16_t naddrs;
75 char *realname;
76 char **aliases;
77 lwres_uint16_t realnamelen;
78 lwres_uint16_t *aliaslen;
79 lwres_addrlist_t addrs;
80 void *base;
81 size_t baselen;
82 } lwres_gabnresponse_t;
83 lwres_gabnrequest_render() uses resolver context ctx to convert
86 getaddrbyname request structure req to canonical format. The packet
87 header structure pkt is initialised and transferred to buffer b. The
88 contents of *req are then appended to the buffer in canonical format.
89 lwres_gabnresponse_render() performs the same task, except it converts
90 a getaddrbyname response structure lwres_gabnresponse_t to the
91 lightweight resolver's canonical format.
92 lwres_gabnrequest_parse() uses context ctx to convert the contents of
94 packet pkt to a lwres_gabnrequest_t structure. Buffer b provides space
95 to be used for storing this structure. When the function succeeds, the
96 resulting lwres_gabnrequest_t is made available through *structp.
97 lwres_gabnresponse_parse() offers the same semantics as
98 lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t
99 structure.
100 lwres_gabnresponse_free() and lwres_gabnrequest_free() release the
102 memory in resolver context ctx that was allocated to the
103 lwres_gabnresponse_t or lwres_gabnrequest_t structures referenced via
104 structp. Any memory associated with ancillary buffers and strings for
105 those structures is also discarded.
106
108 The getaddrbyname opcode functions lwres_gabnrequest_render(),
109 lwres_gabnresponse_render() lwres_gabnrequest_parse() and
110 lwres_gabnresponse_parse() all return LWRES_R_SUCCESS on success. They
111 return LWRES_R_NOMEMORY if memory allocation fails.
112 LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
113 b is too small to accommodate the packet header or the
114 lwres_gabnrequest_t and lwres_gabnresponse_t structures.
115 lwres_gabnrequest_parse() and lwres_gabnresponse_parse() will return
116 LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
117 received packet. These functions will return LWRES_R_FAILURE if
118 pktflags in the packet header structure lwres_lwpacket_t indicate that
119 the packet is not a response to an earlier query.
120
122 lwres_packet(3)
123
125 Copyright © 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
126 Copyright © 2000, 2001 Internet Software Consortium.
127BIND9 Jun 30, 2000 LWRES_GABN(3)