lib/isc/hex.c

	hex.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
 * Copyright (C) 2000-2005, 2007, 2008, 2013-2016  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: hex.c,v 1.20 2008/09/25 04:02:39 tbox Exp $ */

/*! \file */

#include <config.h>

#include <ctype.h>

#include <isc/buffer.h>
#include <isc/hex.h>
#include <isc/lex.h>
#include <isc/string.h>
#include <isc/util.h>

#define RETERR(x) do { \
    isc_result_t _r = (x); \
    if (_r != ISC_R_SUCCESS) \
        return (_r); \
    } while (0)


/*
 * BEW: These static functions are copied from lib/dns/rdata.c.
 */
static isc_result_t
str_totext(const char *source, isc_buffer_t *target);

static isc_result_t
mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);

static const char hex[] = "0123456789ABCDEF";

isc_result_t
isc_hex_totext(isc_region_t *source, int wordlength,
           const char *wordbreak, isc_buffer_t *target)
{
    char buf[3];
    unsigned int loops = 0;

    if (wordlength < 2)
        wordlength = 2;

    memset(buf, 0, sizeof(buf));
    while (source->length > 0) {
        buf[0] = hex[(source->base[0] >> 4) & 0xf];
        buf[1] = hex[(source->base[0]) & 0xf];
        RETERR(str_totext(buf, target));
        isc_region_consume(source, 1);

        loops++;
        if (source->length != 0 &&
            (int)((loops + 1) * 2) >= wordlength)
        {
            loops = 0;
            RETERR(str_totext(wordbreak, target));
        }
    }
    return (ISC_R_SUCCESS);
}

/*%
 * State of a hex decoding process in progress.
 */
typedef struct {
    int length;     /*%< Desired length of binary data or -1 */
    isc_buffer_t *target;   /*%< Buffer for resulting binary data */
    int digits;     /*%< Number of buffered hex digits */
    int val[2];
} hex_decode_ctx_t;

static inline void
hex_decode_init(hex_decode_ctx_t *ctx, int length, isc_buffer_t *target)
{
    ctx->digits = 0;
    ctx->length = length;
    ctx->target = target;
}

static inline isc_result_t
hex_decode_char(hex_decode_ctx_t *ctx, int c) {
    const char *s;

    if ((s = strchr(hex, toupper(c))) == NULL)
        return (ISC_R_BADHEX);
    ctx->val[ctx->digits++] = (int)(s - hex);
    if (ctx->digits == 2) {
        unsigned char num;

        num = (ctx->val[0] << 4) + (ctx->val[1]);
        RETERR(mem_tobuffer(ctx->target, &num, 1));
        if (ctx->length >= 0) {
            if (ctx->length == 0)
                return (ISC_R_BADHEX);
            else
                ctx->length -= 1;
        }
        ctx->digits = 0;
    }
    return (ISC_R_SUCCESS);
}

static inline isc_result_t
hex_decode_finish(hex_decode_ctx_t *ctx) {
    if (ctx->length > 0)
        return (ISC_R_UNEXPECTEDEND);
    if (ctx->digits != 0)
        return (ISC_R_BADHEX);
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
    hex_decode_ctx_t ctx;
    isc_textregion_t *tr;
    isc_token_t token;
    isc_boolean_t eol;

    hex_decode_init(&ctx, length, target);

    while (ctx.length != 0) {
        unsigned int i;

        if (length > 0)
            eol = ISC_FALSE;
        else
            eol = ISC_TRUE;
        RETERR(isc_lex_getmastertoken(lexer, &token,
                          isc_tokentype_string, eol));
        if (token.type != isc_tokentype_string)
            break;
        tr = &token.value.as_textregion;
        for (i = 0; i < tr->length; i++)
            RETERR(hex_decode_char(&ctx, tr->base[i]));
    }
    if (ctx.length < 0)
        isc_lex_ungettoken(lexer, &token);
    RETERR(hex_decode_finish(&ctx));
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_hex_decodestring(const char *cstr, isc_buffer_t *target) {
    hex_decode_ctx_t ctx;

    hex_decode_init(&ctx, -1, target);
    for (;;) {
        int c = *cstr++;
        if (c == '\0')
            break;
        if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
            continue;
        RETERR(hex_decode_char(&ctx, c));
    }
    RETERR(hex_decode_finish(&ctx));
    return (ISC_R_SUCCESS);
}

static isc_result_t
str_totext(const char *source, isc_buffer_t *target) {
    unsigned int l;
    isc_region_t region;

    isc_buffer_availableregion(target, &region);
    l = strlen(source);

    if (l > region.length)
        return (ISC_R_NOSPACE);

    memmove(region.base, source, l);
    isc_buffer_add(target, l);
    return (ISC_R_SUCCESS);
}

static isc_result_t
mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
    isc_region_t tr;

    isc_buffer_availableregion(target, &tr);
    if (length > tr.length)
        return (ISC_R_NOSPACE);
    memmove(tr.base, base, length);
    isc_buffer_add(target, length);
    return (ISC_R_SUCCESS);
}