lib/isc/base64.c

	base64.c revision 2c9c7c5bb5975a18925c30aeb33a26094902f1c1
/*
 * Copyright (C) 1998-2000  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM 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: base64.c,v 1.19 2000/09/08 00:34:21 gson Exp $ */

#include <config.h>

#include <isc/base64.h>
#include <isc/buffer.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)


/*
 * These static functions are also present in lib/dns/rdata.c.  I'm not
 * sure where they should go. -- bwelling
 */
static isc_result_t
str_totext(const char *source, isc_buffer_t *target);

static isc_result_t
gettoken(isc_lex_t *lexer, isc_token_t *token, isc_tokentype_t expect,
     isc_boolean_t eol);

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

static const char base64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

isc_result_t
isc_base64_totext(isc_region_t *source, int wordlength,
          const char *wordbreak, isc_buffer_t *target)
{
    char buf[5];
    unsigned int loops = 0;

    if (wordlength < 4)
        wordlength = 4;

    memset(buf, 0, sizeof buf);
    while (source->length > 2) {
        buf[0] = base64[(source->base[0]>>2)&0x3f];
        buf[1] = base64[((source->base[0]<<4)&0x30)|
                ((source->base[1]>>4)&0x0f)];
        buf[2] = base64[((source->base[1]<<2)&0x3c)|
                ((source->base[2]>>6)&0x03)];
        buf[3] = base64[source->base[2]&0x3f];
        RETERR(str_totext(buf, target));
        isc_region_consume(source, 3);

        loops++;
        if (source->length != 0 &&
            (int)((loops + 1) * 4) >= wordlength)
        {
            loops = 0;
            RETERR(str_totext(wordbreak, target));
        }
    }
    if (source->length == 2) {
        buf[0] = base64[(source->base[0]>>2)&0x3f];
        buf[1] = base64[((source->base[0]<<4)&0x30)|
                ((source->base[1]>>4)&0x0f)];
        buf[2] = base64[((source->base[1]<<2)&0x3c)];
        buf[3] = '=';
        RETERR(str_totext(buf, target));
    } else if (source->length == 1) {
        buf[0] = base64[(source->base[0]>>2)&0x3f];
        buf[1] = base64[((source->base[0]<<4)&0x30)];
        buf[2] = buf[3] = '=';
        RETERR(str_totext(buf, target));
    }
    return (ISC_R_SUCCESS);
}

/*
 * State of a base64 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 base64 digits */
    isc_boolean_t seen_end; /* True if "=" end marker seen */
    int val[4];
} base64_decode_ctx_t;

static inline void
base64_decode_init(base64_decode_ctx_t *ctx, int length, isc_buffer_t *target)
{
    ctx->digits = 0;
    ctx->seen_end = ISC_FALSE;
    ctx->length = length;
    ctx->target = target;
}

static inline isc_result_t
base64_decode_char(base64_decode_ctx_t *ctx, int c) {
    char *s;

    if (ctx->seen_end)
        return (ISC_R_BADBASE64);
    if ((s = strchr(base64, c)) == NULL)
        return (ISC_R_BADBASE64);
    ctx->val[ctx->digits++] = s - base64;
    if (ctx->digits == 4) {
        int n;
        unsigned char buf[3];
        if (ctx->val[0] == 64 || ctx->val[1] == 64)
            return (ISC_R_BADBASE64);
        if (ctx->val[2] == 64 && ctx->val[3] != 64)
            return (ISC_R_BADBASE64);
        n = (ctx->val[2] == 64) ? 1 :
            (ctx->val[3] == 64) ? 2 : 3;
        if (n != 3) {
            ctx->seen_end = ISC_TRUE;
            if (ctx->val[2] == 64)
                ctx->val[2] = 0;
            if (ctx->val[3] == 64)
                ctx->val[3] = 0;
        }
        buf[0] = (ctx->val[0]<<2)|(ctx->val[1]>>4);
        buf[1] = (ctx->val[1]<<4)|(ctx->val[2]>>2);
        buf[2] = (ctx->val[2]<<6)|(ctx->val[3]);
        RETERR(mem_tobuffer(ctx->target, buf, n));
        if (ctx->length >= 0) {
            if (n > ctx->length)
                return (ISC_R_BADBASE64);
            else
                ctx->length -= n;
        }
        ctx->digits = 0;
    }
    return (ISC_R_SUCCESS);
}

static inline isc_result_t
base64_decode_finish(base64_decode_ctx_t *ctx) {
    if (ctx->length > 0)
        return (ISC_R_UNEXPECTEDEND);
    if (ctx->digits != 0)
        return (ISC_R_BADBASE64);
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_base64_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
    base64_decode_ctx_t ctx;
    isc_textregion_t *tr;
    isc_token_t token;

    base64_decode_init(&ctx, length, target);

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

        if (length > 0)
            RETERR(gettoken(lexer, &token, isc_tokentype_string,
                    ISC_FALSE));
        else
            RETERR(gettoken(lexer, &token, isc_tokentype_string,
                    ISC_TRUE));
        if (token.type != isc_tokentype_string)
            break;
        tr = &token.value.as_textregion;
        for (i = 0 ;i < tr->length; i++)
            RETERR(base64_decode_char(&ctx, tr->base[i]));
    }
    if (ctx.length < 0 && !ctx.seen_end)
        isc_lex_ungettoken(lexer, &token);
    RETERR(base64_decode_finish(&ctx));
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_base64_decodestring(isc_mem_t *mctx, char *cstr, isc_buffer_t *target) {
    base64_decode_ctx_t ctx;

    UNUSED(mctx);

    base64_decode_init(&ctx, -1, target);
    for (;;) {
        int c = *cstr++;
        if (c == '\0')
            break;
        if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
            continue;
        RETERR(base64_decode_char(&ctx, c));
    }
    RETERR(base64_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);

    memcpy(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);
    memcpy(tr.base, base, length);
    isc_buffer_add(target, length);
    return (ISC_R_SUCCESS);
}

static isc_result_t
gettoken(isc_lex_t *lexer, isc_token_t *token, isc_tokentype_t expect,
     isc_boolean_t eol)
{
    unsigned int options = ISC_LEXOPT_EOL | ISC_LEXOPT_EOF |
                   ISC_LEXOPT_DNSMULTILINE | ISC_LEXOPT_ESCAPE;
    isc_result_t result;

    if (expect == isc_tokentype_qstring)
        options |= ISC_LEXOPT_QSTRING;
    else if (expect == isc_tokentype_number)
        options |= ISC_LEXOPT_NUMBER;
    result = isc_lex_gettoken(lexer, options, token);
    switch (result) {
    case ISC_R_SUCCESS:
        break;
    case ISC_R_NOMEMORY:
        return (ISC_R_NOMEMORY);
    case ISC_R_NOSPACE:
        return (ISC_R_NOSPACE);
    default:
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_lex_gettoken() failed: %s",
                 isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }
    if (eol && ((token->type == isc_tokentype_eol) ||
            (token->type == isc_tokentype_eof)))
        return (ISC_R_SUCCESS);
    if (token->type == isc_tokentype_string &&
        expect == isc_tokentype_qstring)
        return (ISC_R_SUCCESS);
    if (token->type != expect) {
        isc_lex_ungettoken(lexer, token);
        if (token->type == isc_tokentype_eol ||
            token->type == isc_tokentype_eof)
            return (ISC_R_UNEXPECTEDEND);
        return (ISC_R_UNEXPECTEDTOKEN);
    }
    return (ISC_R_SUCCESS);
}