lwres_gabn.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
* Copyright (C) 2000, 2001, 2004, 2005, 2007, 2013, 2015, 2016 Internet Systems Consortium, Inc. ("ISC")
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
/* $Id: lwres_gabn.c,v 1.33 2007/06/19 23:47:22 tbox Exp $ */
/*! \file lwres_gabn.c
These are low-level routines for creating and parsing lightweight
resolver name-to-address lookup request and response messages.
There are four main functions for the getaddrbyname opcode. One render
function converts a getaddrbyname request structure --
lwres_gabnrequest_t -- to the lighweight resolver's canonical format.
It is complemented by a parse function that converts a packet in this
canonical format to a getaddrbyname request structure. Another render
function converts the getaddrbyname response structure --
lwres_gabnresponse_t -- to the canonical format. This is complemented
by a parse function which converts a packet in canonical format to a
getaddrbyname response structure.
\code
#define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint32_t addrtypes;
lwres_uint16_t namelen;
char *name;
} lwres_gabnrequest_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
lwres_uint16_t naddrs;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
lwres_addrlist_t addrs;
void *base;
size_t baselen;
} lwres_gabnresponse_t;
\endcode
lwres_gabnrequest_render() uses resolver context ctx to convert
getaddrbyname request structure req to canonical format. The packet
header structure pkt is initialised and transferred to buffer b. The
contents of *req are then appended to the buffer in canonical format.
lwres_gabnresponse_render() performs the same task, except it converts
a getaddrbyname response structure lwres_gabnresponse_t to the
lightweight resolver's canonical format.
lwres_gabnrequest_parse() uses context ctx to convert the contents of
packet pkt to a lwres_gabnrequest_t structure. Buffer b provides space
to be used for storing this structure. When the function succeeds, the
resulting lwres_gabnrequest_t is made available through *structp.
lwres_gabnresponse_parse() offers the same semantics as
lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t
structure.
lwres_gabnresponse_free() and lwres_gabnrequest_free() release the
memory in resolver context ctx that was allocated to the
lwres_gabnresponse_t or lwres_gabnrequest_t structures referenced via
structp. Any memory associated with ancillary buffers and strings for
those structures is also discarded.
\section lwres_gabn_return Return Values
The getaddrbyname opcode functions lwres_gabnrequest_render(),
lwres_gabnresponse_render() lwres_gabnrequest_parse() and
lwres_gabnresponse_parse() all return #LWRES_R_SUCCESS on success. They
return #LWRES_R_NOMEMORY if memory allocation fails.
#LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
b is too small to accommodate the packet header or the
lwres_gabnrequest_t and lwres_gabnresponse_t structures.
lwres_gabnrequest_parse() and lwres_gabnresponse_parse() will return
#LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
received packet. These functions will return #LWRES_R_FAILURE if
pktflags in the packet header structure #lwres_lwpacket_t indicate that
the packet is not a response to an earlier query.
\section lwres_gabn_see See Also
\link lwpacket.c lwres_lwpacket \endlink
*/
#include <config.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <lwres/lwbuffer.h>
#include <lwres/lwpacket.h>
#include "context_p.h"
#include "assert_p.h"
/*% uses resolver context ctx to convert getaddrbyname request structure req to canonical format. */
{
unsigned char *buf;
int ret;
return (LWRES_R_NOMEMORY);
pkt->authlength = 0;
if (ret != LWRES_R_SUCCESS) {
return (ret);
}
/*
* Flags.
*/
/*
* Address types we'll accept.
*/
/*
* Put the length and the data. We know this will fit because we
* just checked for it.
*/
lwres_buffer_putuint8(b, 0); /* trailing NUL */
INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
return (LWRES_R_SUCCESS);
}
/*% converts a getaddrbyname response structure lwres_gabnresponse_t to the lightweight resolver's canonical format. */
{
unsigned char *buf;
int ret;
int x;
/* naliases, naddrs */
/* real name encoding */
/* each alias */
/* each address */
x = 0;
x++;
}
return (LWRES_R_NOMEMORY);
pkt->authlength = 0;
if (ret != LWRES_R_SUCCESS) {
return (ret);
}
/*
* Check space needed here.
*/
/* Flags. */
/* encode naliases and naddrs */
/* encode the real name */
lwres_buffer_putuint8(b, 0);
/* encode the aliases */
datalen);
lwres_buffer_putuint8(b, 0);
}
/* encode the addresses */
}
INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
return (LWRES_R_SUCCESS);
}
/*% Uses context ctx to convert the contents of packet pkt to a lwres_gabnrequest_t structure. */
{
int ret;
char *name;
return (LWRES_R_FAILURE);
return (LWRES_R_UNEXPECTEDEND);
flags = lwres_buffer_getuint32(b);
/*
* Pull off the name itself
*/
if (ret != LWRES_R_SUCCESS)
return (ret);
if (LWRES_BUFFER_REMAINING(b) != 0)
return (LWRES_R_TRAILINGDATA);
return (LWRES_R_NOMEMORY);
return (LWRES_R_SUCCESS);
}
/*% Offers the same semantics as lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t structure. */
{
unsigned int x;
return (LWRES_R_FAILURE);
/*
* Pull off the name itself
*/
return (LWRES_R_UNEXPECTEDEND);
flags = lwres_buffer_getuint32(b);
naddrs = lwres_buffer_getuint16(b);
return (LWRES_R_NOMEMORY);
if (naliases > 0) {
goto out;
}
goto out;
}
}
for (x = 0; x < naddrs; x++) {
goto out;
}
}
/*
* Now, pull off the real name.
*/
if (ret != LWRES_R_SUCCESS)
goto out;
/*
* Parse off the aliases.
*/
if (ret != LWRES_R_SUCCESS)
goto out;
}
/*
* Pull off the addresses. We already strung the linked list
* up above.
*/
if (ret != LWRES_R_SUCCESS)
goto out;
}
if (LWRES_BUFFER_REMAINING(b) != 0) {
goto out;
}
return (LWRES_R_SUCCESS);
out:
sizeof(lwres_uint16_t) * naliases);
}
}
return (ret);
}
/*% Release the memory in resolver context ctx that was allocated to the lwres_gabnrequest_t. */
void
{
}
/*% Release the memory in resolver context ctx that was allocated to the lwres_gabnresponse_t. */
void
{
}
}
}