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16 .\" $Id: lwres_context.3,v 1.13.2.2.2.7 2006/06/29 13:02:31 marka Exp $
20 .\" Title: lwres_context
22 .\" Generator: DocBook XSL Stylesheets v1.70.1 <http://docbook.sf.net/>
23 .\" Date: Jun 30, 2000
27 .TH "LWRES_CONTEXT" "3" "Jun 30, 2000" "BIND9" "BIND9"
28 .\" disable hyphenation
30 .\" disable justification (adjust text to left margin only)
33 lwres_context_create, lwres_context_destroy, lwres_context_nextserial, lwres_context_initserial, lwres_context_freemem, lwres_context_allocmem, lwres_context_sendrecv \- lightweight resolver context management
36 #include <lwres/lwres.h>
39 .BI "lwres_result_t lwres_context_create(lwres_context_t\ **contextp, void\ *arg, lwres_malloc_t\ malloc_function, lwres_free_t\ free_function);"
41 .BI "lwres_result_t lwres_context_destroy(lwres_context_t\ **contextp);"
43 .BI "void lwres_context_initserial(lwres_context_t\ *ctx, lwres_uint32_t\ serial);"
45 .BI "lwres_uint32_t lwres_context_nextserial(lwres_context_t\ *ctx);"
47 .BI "void lwres_context_freemem(lwres_context_t\ *ctx, void\ *mem, size_t\ len);"
49 .BI "void lwres_context_allocmem(lwres_context_t\ *ctx, size_t\ len);"
51 .BI "void * lwres_context_sendrecv(lwres_context_t\ *ctx, void\ *sendbase, int\ sendlen, void\ *recvbase, int\ recvlen, int\ *recvd_len);"
54 \fBlwres_context_create()\fR
57 structure for use in lightweight resolver operations. It holds a socket and other data needed for communicating with a resolver daemon. The new
60 \fIcontextp\fR, a pointer to a
64 pointer must initially be NULL, and is modified to point to the newly created
65 \fBlwres_context_t\fR.
67 When the lightweight resolver needs to perform dynamic memory allocation, it will call
69 to allocate memory and
75 are NULL, memory is allocated using .Xr malloc 3 and
76 \fBfree\fR(3). It is not permitted to have a NULL
82 is passed as the first parameter to the memory allocation functions. If
88 is unused and should be passed as NULL.
90 Once memory for the structure has been allocated, it is initialized using
91 \fBlwres_conf_init\fR(3)
95 \fBlwres_context_destroy()\fR
97 \fBlwres_context_t\fR, closing its socket.
99 is a pointer to a pointer to the context that is to be destroyed. The pointer will be set to NULL when the context has been destroyed.
101 The context holds a serial number that is used to identify resolver request packets and associate responses with the corresponding requests. This serial number is controlled using
102 \fBlwres_context_initserial()\fR
104 \fBlwres_context_nextserial()\fR.
105 \fBlwres_context_initserial()\fR
106 sets the serial number for context
110 \fBlwres_context_nextserial()\fR
111 increments the serial number and returns the previous value.
113 Memory for a lightweight resolver context is allocated and freed using
114 \fBlwres_context_allocmem()\fR
116 \fBlwres_context_freemem()\fR. These use whatever allocations were defined when the context was created with
117 \fBlwres_context_create()\fR.
118 \fBlwres_context_allocmem()\fR
121 bytes of memory and if successful returns a pointer to the allocated storage.
122 \fBlwres_context_freemem()\fR
125 bytes of space starting at location
128 \fBlwres_context_sendrecv()\fR
129 performs I/O for the context
130 \fIctx\fR. Data are read and written from the context's socket. It writes data from
132 \(em typically a lightweight resolver query packet \(em and waits for a reply which is copied to the receive buffer at
133 \fIrecvbase\fR. The number of bytes that were written to this receive buffer is returned in
137 \fBlwres_context_create()\fR
139 \fBLWRES_R_NOMEMORY\fR
141 \fBstruct lwres_context\fR
142 could not be allocated,
143 \fBLWRES_R_SUCCESS\fR
146 Successful calls to the memory allocator
147 \fBlwres_context_allocmem()\fR
148 return a pointer to the start of the allocated space. It returns NULL if memory could not be allocated.
150 \fBLWRES_R_SUCCESS\fR
152 \fBlwres_context_sendrecv()\fR
153 completes successfully.
154 \fBLWRES_R_IOERROR\fR
155 is returned if an I/O error occurs and
156 \fBLWRES_R_TIMEOUT\fR
158 \fBlwres_context_sendrecv()\fR
159 times out waiting for a response.
162 \fBlwres_conf_init\fR(3),
166 Copyright \(co 2004, 2005 Internet Systems Consortium, Inc. ("ISC")