compress.c

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/*
 * Copyright (C) 2004-2007, 2015  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

/*! \file */

#define DNS_NAME_USEINLINE 1

#include <config.h>

#include <isc/mem.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/compress.h>
#include <dns/fixedname.h>
#include <dns/rbt.h>
#include <dns/result.h>

#define CCTX_MAGIC      ISC_MAGIC('C', 'C', 'T', 'X')
#define VALID_CCTX(x)   ISC_MAGIC_VALID(x, CCTX_MAGIC)

#define DCTX_MAGIC      ISC_MAGIC('D', 'C', 'T', 'X')
#define VALID_DCTX(x)   ISC_MAGIC_VALID(x, DCTX_MAGIC)

/***
 ***    Compression
 ***/

isc_result_t
dns_compress_init(dns_compress_t *cctx, int edns, isc_mem_t *mctx) {
        unsigned int i;

        REQUIRE(cctx != NULL);
        REQUIRE(mctx != NULL);  /* See: rdataset.c:towiresorted(). */

        cctx->allowed = 0;
        cctx->edns = edns;
        for (i = 0; i < DNS_COMPRESS_TABLESIZE; i++)
                cctx->table[i] = NULL;
        cctx->mctx = mctx;
        cctx->count = 0;
        cctx->magic = CCTX_MAGIC;
        return (ISC_R_SUCCESS);
}

void
dns_compress_invalidate(dns_compress_t *cctx) {
        dns_compressnode_t *node;
        unsigned int i;

        REQUIRE(VALID_CCTX(cctx));

        cctx->magic = 0;
        for (i = 0; i < DNS_COMPRESS_TABLESIZE; i++) {
                while (cctx->table[i] != NULL) {
                        node = cctx->table[i];
                        cctx->table[i] = cctx->table[i]->next;
                        if ((node->offset & 0x8000) != 0)
                                isc_mem_put(cctx->mctx, node->r.base,
                                            node->r.length);
                        if (node->count < DNS_COMPRESS_INITIALNODES)
                                continue;
                        isc_mem_put(cctx->mctx, node, sizeof(*node));
                }
        }
        cctx->allowed = 0;
        cctx->edns = -1;
}

void
dns_compress_setmethods(dns_compress_t *cctx, unsigned int allowed) {
        REQUIRE(VALID_CCTX(cctx));

        cctx->allowed &= ~DNS_COMPRESS_ALL;
        cctx->allowed |= (allowed & DNS_COMPRESS_ALL);
}

unsigned int
dns_compress_getmethods(dns_compress_t *cctx) {
        REQUIRE(VALID_CCTX(cctx));
        return (cctx->allowed & DNS_COMPRESS_ALL);
}

void
dns_compress_setsensitive(dns_compress_t *cctx, isc_boolean_t sensitive) {
        REQUIRE(VALID_CCTX(cctx));

        if (sensitive)
                cctx->allowed |= DNS_COMPRESS_CASESENSITIVE;
        else
                cctx->allowed &= ~DNS_COMPRESS_CASESENSITIVE;
}

isc_boolean_t
dns_compress_getsensitive(dns_compress_t *cctx) {
        REQUIRE(VALID_CCTX(cctx));

        return (ISC_TF((cctx->allowed & DNS_COMPRESS_CASESENSITIVE) != 0));
}

int
dns_compress_getedns(dns_compress_t *cctx) {
        REQUIRE(VALID_CCTX(cctx));
        return (cctx->edns);
}

#define NODENAME(node, name) \
do { \
        (name)->length = (node)->r.length; \
        (name)->labels = (node)->labels; \
        (name)->ndata = (node)->r.base; \
        (name)->attributes = DNS_NAMEATTR_ABSOLUTE; \
} while (0)

/*
 * Find the longest match of name in the table.
 * If match is found return ISC_TRUE. prefix, suffix and offset are updated.
 * If no match is found return ISC_FALSE.
 */
isc_boolean_t
dns_compress_findglobal(dns_compress_t *cctx, const dns_name_t *name,
                        dns_name_t *prefix, isc_uint16_t *offset)
{
        dns_name_t tname, nname;
        dns_compressnode_t *node = NULL;
        unsigned int labels, hash, n;

        REQUIRE(VALID_CCTX(cctx));
        REQUIRE(dns_name_isabsolute(name) == ISC_TRUE);
        REQUIRE(offset != NULL);

        if (cctx->count == 0)
                return (ISC_FALSE);

        labels = dns_name_countlabels(name);
        INSIST(labels > 0);

        dns_name_init(&tname, NULL);
        dns_name_init(&nname, NULL);

        for (n = 0; n < labels - 1; n++) {
                dns_name_getlabelsequence(name, n, labels - n, &tname);
                hash = dns_name_hash(&tname, ISC_FALSE) %
                       DNS_COMPRESS_TABLESIZE;
                for (node = cctx->table[hash]; node != NULL; node = node->next)
                {
                        NODENAME(node, &nname);
                        if ((cctx->allowed & DNS_COMPRESS_CASESENSITIVE) != 0) {
                                if (dns_name_caseequal(&nname, &tname))
                                        break;
                        } else {
                                if (dns_name_equal(&nname, &tname))
                                        break;
                        }
                }
                if (node != NULL)
                        break;
        }

        /*
         * If node == NULL, we found no match at all.
         */
        if (node == NULL)
                return (ISC_FALSE);

        if (n == 0)
                dns_name_reset(prefix);
        else
                dns_name_getlabelsequence(name, 0, n, prefix);

        *offset = (node->offset & 0x7fff);
        return (ISC_TRUE);
}

static inline unsigned int
name_length(const dns_name_t *name) {
        isc_region_t r;
        dns_name_toregion(name, &r);
        return (r.length);
}

void
dns_compress_add(dns_compress_t *cctx, const dns_name_t *name,
                 const dns_name_t *prefix, isc_uint16_t offset)
{
        dns_name_t tname, xname;
        unsigned int start;
        unsigned int n;
        unsigned int count;
        unsigned int hash;
        dns_compressnode_t *node;
        unsigned int length;
        unsigned int tlength;
        isc_uint16_t toffset;
        unsigned char *tmp;
        isc_region_t r;

        REQUIRE(VALID_CCTX(cctx));
        REQUIRE(dns_name_isabsolute(name));

        if (offset > 0x4000)
                return;
        dns_name_init(&tname, NULL);
        dns_name_init(&xname, NULL);

        n = dns_name_countlabels(name);
        count = dns_name_countlabels(prefix);
        if (dns_name_isabsolute(prefix))
                count--;
        if (count == 0)
                return;
        start = 0;
        dns_name_toregion(name, &r);
        length = r.length;
        tmp = isc_mem_get(cctx->mctx, length);
        if (tmp == NULL)
                return;
        memmove(tmp, r.base, r.length);
        r.base = tmp;
        dns_name_fromregion(&xname, &r);

        while (count > 0) {
                if (offset >= 0x4000)
                        break;
                dns_name_getlabelsequence(&xname, start, n, &tname);
                hash = dns_name_hash(&tname, ISC_FALSE) %
                       DNS_COMPRESS_TABLESIZE;
                tlength = name_length(&tname);
                toffset = (isc_uint16_t)(offset + (length - tlength));
                /*
                 * Create a new node and add it.
                 */
                if (cctx->count < DNS_COMPRESS_INITIALNODES)
                        node = &cctx->initialnodes[cctx->count];
                else {
                        node = isc_mem_get(cctx->mctx,
                                           sizeof(dns_compressnode_t));
                        if (node == NULL) {
                                if (start == 0)
                                        isc_mem_put(cctx->mctx,
                                                    r.base, r.length);
                                return;
                        }
                }
                node->count = cctx->count++;
                if (start == 0)
                        toffset |= 0x8000;
                node->offset = toffset;
                dns_name_toregion(&tname, &node->r);
                node->labels = (isc_uint8_t)dns_name_countlabels(&tname);
                node->next = cctx->table[hash];
                cctx->table[hash] = node;
                start++;
                n--;
                count--;
        }
}

void
dns_compress_rollback(dns_compress_t *cctx, isc_uint16_t offset) {
        unsigned int i;
        dns_compressnode_t *node;

        REQUIRE(VALID_CCTX(cctx));

        for (i = 0; i < DNS_COMPRESS_TABLESIZE; i++) {
                node = cctx->table[i];
                /*
                 * This relies on nodes with greater offsets being
                 * closer to the beginning of the list, and the
                 * items with the greatest offsets being at the end
                 * of the initialnodes[] array.
                 */
                while (node != NULL && (node->offset & 0x7fff) >= offset) {
                        cctx->table[i] = node->next;
                        if ((node->offset & 0x8000) != 0)
                                isc_mem_put(cctx->mctx, node->r.base,
                                            node->r.length);
                        if (node->count >= DNS_COMPRESS_INITIALNODES)
                                isc_mem_put(cctx->mctx, node, sizeof(*node));
                        cctx->count--;
                        node = cctx->table[i];
                }
        }
}

/***
 ***    Decompression
 ***/

void
dns_decompress_init(dns_decompress_t *dctx, int edns,
                    dns_decompresstype_t type) {

        REQUIRE(dctx != NULL);
        REQUIRE(edns >= -1 && edns <= 255);

        dctx->allowed = DNS_COMPRESS_NONE;
        dctx->edns = edns;
        dctx->type = type;
        dctx->magic = DCTX_MAGIC;
}

void
dns_decompress_invalidate(dns_decompress_t *dctx) {

        REQUIRE(VALID_DCTX(dctx));

        dctx->magic = 0;
}

void
dns_decompress_setmethods(dns_decompress_t *dctx, unsigned int allowed) {

        REQUIRE(VALID_DCTX(dctx));

        switch (dctx->type) {
        case DNS_DECOMPRESS_ANY:
                dctx->allowed = DNS_COMPRESS_ALL;
                break;
        case DNS_DECOMPRESS_NONE:
                dctx->allowed = DNS_COMPRESS_NONE;
                break;
        case DNS_DECOMPRESS_STRICT:
                dctx->allowed = allowed;
                break;
        }
}

unsigned int
dns_decompress_getmethods(dns_decompress_t *dctx) {

        REQUIRE(VALID_DCTX(dctx));

        return (dctx->allowed);
}

int
dns_decompress_edns(dns_decompress_t *dctx) {

        REQUIRE(VALID_DCTX(dctx));

        return (dctx->edns);
}

dns_decompresstype_t
dns_decompress_type(dns_decompress_t *dctx) {

        REQUIRE(VALID_DCTX(dctx));

        return (dctx->type);
}

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