/* Copyright (C) 2007-2012 Open Information Security Foundation

 *

 * You can copy, redistribute or modify this Program under the terms of

 * the GNU General Public License version 2 as published by the Free

 * Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * version 2 along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

/**

 * \file

 *

 * \author David Abarbanel <david.abarbanel@baesystems.com>

 *

 */

#include "util-base64.h"

#include "util-debug.h"

#include "util-unittest.h"

/* Constants */

#define BASE64_TABLE_MAX  122

/* Base64 character to index conversion table */

/* Characters are mapped as "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" */

static const int b64table[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,

        54, 55, 56, 57, 58, 59, 60, 61, -1, -1,

        -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,

        5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

        15, 16, 17, 18, 19, 20, 21, 22, 23, 24,

        25, -1, -1, -1, -1, -1, -1, 26, 27, 28,

        29, 30, 31, 32, 33, 34, 35, 36, 37, 38,

        39, 40, 41, 42, 43, 44, 45, 46, 47, 48,

        49, 50, 51 };

/**

 * \brief Gets a base64-decoded value from an encoded character

 *

 * \param c The encoded character

 *

 * \return The decoded value (0 or above), or -1 if the parameter is invalid

 */

static inline int GetBase64Value(uint8_t c)

{

    int val = -1;

    /* Pull from conversion table */

    if (c <= BASE64_TABLE_MAX) {

        val = b64table[(int) c];

    }

    return val;

}

/**

 * \brief Checks if the given char in a byte array is Base64 alphabet

 *

 * \param Char that needs to be checked

 *

 * \return True if the char was Base64 alphabet, False otherwise

 */

bool IsBase64Alphabet(uint8_t encoded_byte)

{

    if (GetBase64Value(encoded_byte) < 0 && encoded_byte != '=') {

        return false;

    }

    return true;

}

/**

 * \brief Decodes a 4-byte base64-encoded block into a 3-byte ascii-encoded block

 *

 * \param ascii the 3-byte ascii output block

 * \param b64 the 4-byte base64 input block

 *

 * \return none

 */

static inline void DecodeBase64Block(uint8_t ascii[ASCII_BLOCK], uint8_t b64[B64_BLOCK])

{

    ascii[0] = (uint8_t) (b64[0] << 2) | (b64[1] >> 4);

    ascii[1] = (uint8_t) (b64[1] << 4) | (b64[2] >> 2);

    ascii[2] = (uint8_t) (b64[2] << 6) | (b64[3]);

}

/**

 * \brief Decodes a base64-encoded string buffer into an ascii-encoded byte buffer

 *

 * \param dest The destination byte buffer

 * \param dest_size The destination byte buffer size

 * \param src The source string

 * \param len The length of the source string

 * \param consumed_bytes The bytes that were actually processed/consumed

 * \param decoded_bytes The bytes that were decoded

 * \param mode The mode in which decoding should happen

 *

 * \return Error code indicating success or failures with parsing

 */

Base64Ecode DecodeBase64(uint8_t *dest, uint32_t dest_size, const uint8_t *src, uint32_t len,

        uint32_t *consumed_bytes, uint32_t *decoded_bytes, Base64Mode mode)

{

    int val;

    uint32_t padding = 0, bbidx = 0, sp = 0, leading_sp = 0;

    uint8_t *dptr = dest;

    uint8_t b64[B64_BLOCK] = { 0,0,0,0 };

    bool valid = true;

    Base64Ecode ecode = BASE64_ECODE_OK;

    *decoded_bytes = 0;

    /* Traverse through each alpha-numeric letter in the source array */

    for (uint32_t i = 0; i < len; i++) {

        /* Get decimal representation */

        val = GetBase64Value(src[i]);

        if (val < 0) {

            if (mode == BASE64_MODE_RFC2045 && src[i] != '=') {

                if (bbidx == 0) {

                    /* Special case where last block of data has a leading space or invalid char */

                    leading_sp++;

                }

                sp++;

                continue;

            }

            /* Invalid character found, so decoding fails */

            if (src[i] != '=') {

                valid = false;

                ecode = BASE64_ECODE_ERR;

                if (mode == BASE64_MODE_STRICT) {

                    *decoded_bytes = 0;

                }

                break;

            }

            padding++;

        }

        /* For each alpha-numeric letter in the source array, find the numeric

         * value */

        b64[bbidx++] = (val > 0 ? (uint8_t)val : 0);

        /* Decode every 4 base64 bytes into 3 ascii bytes */

        if (bbidx == B64_BLOCK) {

            /* For every 4 bytes, add 3 bytes but deduct the '=' padded blocks */

            uint32_t numDecoded_blk = ASCII_BLOCK - (padding < B64_BLOCK ? padding : ASCII_BLOCK);

            if (dest_size < *decoded_bytes + numDecoded_blk) {

                SCLogDebug("Destination buffer full");

                ecode = BASE64_ECODE_BUF;

                break;

            }

            if (dest_size - *decoded_bytes < ASCII_BLOCK)

                return BASE64_ECODE_BUF;

            /* Decode base-64 block into ascii block and move pointer */

            DecodeBase64Block(dptr, b64);

            dptr += numDecoded_blk;

            *decoded_bytes += numDecoded_blk;

            /* Reset base-64 block and index */

            bbidx = 0;

            padding = 0;

            *consumed_bytes += B64_BLOCK + sp;

            sp = 0;

            leading_sp = 0;

            memset(&b64, 0, sizeof(b64));

        }

    }

    if (bbidx > 0 && bbidx < 4 && ((!valid && mode == BASE64_MODE_RFC4648))) {

        /* Decoded bytes for 1 or 2 base64 encoded bytes is 1 */

        padding = bbidx > 1 ? B64_BLOCK - bbidx : 2;

        uint32_t numDecoded_blk = ASCII_BLOCK - (padding < B64_BLOCK ? padding : ASCII_BLOCK);

        if (dest_size < *decoded_bytes + numDecoded_blk) {

            SCLogDebug("Destination buffer full");

            ecode = BASE64_ECODE_BUF;

            return ecode;

        }

        /* if the destination size is not at least 3 Bytes long, it'll give a dynamic

         * buffer overflow while decoding, so, return and let the caller take care of the

         * remaining bytes to be decoded which should always be < 4 at this stage */

        if (dest_size - *decoded_bytes < ASCII_BLOCK)

            return BASE64_ECODE_BUF;

        *decoded_bytes += numDecoded_blk;

        DecodeBase64Block(dptr, b64);

        *consumed_bytes += bbidx;

    }

    /* Finish remaining b64 bytes by padding */

    if (valid && bbidx > 0 && (mode != BASE64_MODE_RFC2045)) {

        /* Decode remaining */

        if (dest_size - *decoded_bytes < ASCII_BLOCK)

            return BASE64_ECODE_BUF;

        *decoded_bytes += ASCII_BLOCK - (B64_BLOCK - bbidx);

        DecodeBase64Block(dptr, b64);

    }

    if (*decoded_bytes == 0) {

        SCLogDebug("base64 decoding failed");

    }

    *consumed_bytes += leading_sp;

    return ecode;

}

#ifdef UNITTESTS

#define TEST_RFC2045(src, fin_str, dest_size, exp_decoded, exp_consumed, ecode)                    \

    {                                                                                              \

        uint32_t consumed_bytes = 0, num_decoded = 0;                                              \

        uint8_t dst[dest_size];                                                                    \

        Base64Ecode code = DecodeBase64(dst, dest_size, (const uint8_t *)src, strlen(src),         \

                &consumed_bytes, &num_decoded, BASE64_MODE_RFC2045);                               \

        FAIL_IF(code != ecode);                                                                    \

        FAIL_IF(memcmp(dst, fin_str, strlen(fin_str)) != 0);                                       \

        FAIL_IF(num_decoded != exp_decoded);                                                       \

        FAIL_IF(consumed_bytes != exp_consumed);                                                   \

    }

#define TEST_RFC4648(src, fin_str, dest_size, exp_decoded, exp_consumed, ecode)                    \

    {                                                                                              \

        uint32_t consumed_bytes = 0, num_decoded = 0;                                              \

        uint8_t dst[dest_size];                                                                    \

        Base64Ecode code = DecodeBase64(dst, dest_size, (const uint8_t *)src, strlen(src),         \

                &consumed_bytes, &num_decoded, BASE64_MODE_RFC4648);                               \

        FAIL_IF(code != ecode);                                                                    \

        FAIL_IF(memcmp(dst, fin_str, strlen(fin_str)) != 0);                                       \

        FAIL_IF(num_decoded != exp_decoded);                                                       \

        FAIL_IF(consumed_bytes != exp_consumed);                                                   \

    }

static int B64DecodeCompleteString(void)

{

    /*

     * SGVsbG8gV29ybGR6 : Hello Worldz

     * */

    const char *src = "SGVsbG8gV29ybGR6";

    const char *fin_str = "Hello Worldz";

    TEST_RFC2045(src, fin_str, strlen(fin_str), strlen(fin_str), strlen(src), BASE64_ECODE_OK);

    PASS;

}

static int B64DecodeInCompleteString(void)

{

    /*

     * SGVsbG8gV29ybGR6 : Hello Worldz

     * */

    const char *src = "SGVsbG8gV29ybGR";

    const char *fin_str = "Hello Wor";

    TEST_RFC2045(src, fin_str, strlen(fin_str), strlen(fin_str), strlen(src) - 3, BASE64_ECODE_OK);

    PASS;

}

static int B64DecodeCompleteStringWSp(void)

{

    /*

     * SGVsbG8gV29ybGQ= : Hello World

     * */

    const char *src = "SGVs bG8 gV29y bGQ=";

    const char *fin_str = "Hello World";

    TEST_RFC2045(src, fin_str, strlen(fin_str) + 3, strlen(fin_str), strlen(src), BASE64_ECODE_OK);

    PASS;

}

static int B64DecodeInCompleteStringWSp(void)

{

    /*

     * SGVsbG8gV29ybGQ= : Hello World

     * Special handling for this case (sp in remainder) done in ProcessBase64Remainder

     * */

    const char *src = "SGVs bG8 gV29y bGQ";

    const char *fin_str = "Hello Wor";

    TEST_RFC2045(src, fin_str, strlen(fin_str) + 1 /* 12 B in dest_size */, strlen(fin_str),

            strlen(src) - 3, BASE64_ECODE_OK);

    PASS;

}

static int B64DecodeStringBiggerThanBuffer(void)

{

    /*

     * SGVsbG8gV29ybGQ= : Hello World

     * */

    const char *src = "SGVs bG8 gV29y bGQ=";

    const char *fin_str = "Hello Wor";

    TEST_RFC2045(

            src, fin_str, strlen(fin_str) + 1, strlen(fin_str), strlen(src) - 4, BASE64_ECODE_BUF);

    PASS;

}

static int B64DecodeStringEndingSpaces(void)

{

    const char *src = "0YPhA d H";

    uint32_t consumed_bytes = 0, num_decoded = 0;

    uint8_t dst[10];

    Base64Ecode code = DecodeBase64(dst, sizeof(dst), (const uint8_t *)src, strlen(src),

            &consumed_bytes, &num_decoded, BASE64_MODE_RFC2045);

    FAIL_IF(code != BASE64_ECODE_OK);

    FAIL_IF(num_decoded != 3);

    FAIL_IF(consumed_bytes != 4);

    PASS;

}

static int B64TestVectorsRFC2045(void)

{

    const char *src1 = "";

    const char *fin_str1 = "";

    const char *src2 = "Zg==";

    const char *fin_str2 = "f";

    const char *src3 = "Zm8=";

    const char *fin_str3 = "fo";

    const char *src4 = "Zm9v";

    const char *fin_str4 = "foo";

    const char *src5 = "Zm9vYg==";

    const char *fin_str5 = "foob";

    const char *src6 = "Zm9vYmE=";

    const char *fin_str6 = "fooba";

    const char *src7 = "Zm9vYmFy";

    const char *fin_str7 = "foobar";

    const char *src8 = "Zm 9v Ym Fy";

    const char *fin_str8 = "foobar";

    const char *src9 = "Zm$9vYm.Fy";

    const char *fin_str9 = "foobar";

    const char *src10 = "Y21Wd2IzSjBaVzFoYVd4bWNtRjFaRUJoZEc4dVoyOTJMbUYxOmpqcHh4b3Rhb2w%5";

    const char *fin_str10 = "cmVwb3J0ZW1haWxmcmF1ZEBhdG8uZ292LmF1:jjpxxotaol9";

    TEST_RFC2045(src1, fin_str1, ASCII_BLOCK * 2, strlen(fin_str1), strlen(src1), BASE64_ECODE_OK);

    TEST_RFC2045(src2, fin_str2, ASCII_BLOCK * 2, strlen(fin_str2), strlen(src2), BASE64_ECODE_OK);

    TEST_RFC2045(src3, fin_str3, ASCII_BLOCK * 2, strlen(fin_str3), strlen(src3), BASE64_ECODE_OK);

    TEST_RFC2045(src4, fin_str4, ASCII_BLOCK * 2, strlen(fin_str4), strlen(src4), BASE64_ECODE_OK);

    TEST_RFC2045(src5, fin_str5, ASCII_BLOCK * 2, strlen(fin_str5), strlen(src5), BASE64_ECODE_OK);

    TEST_RFC2045(src6, fin_str6, ASCII_BLOCK * 2, strlen(fin_str6), strlen(src6), BASE64_ECODE_OK);

    TEST_RFC2045(src7, fin_str7, ASCII_BLOCK * 2, strlen(fin_str7), strlen(src7), BASE64_ECODE_OK);

    TEST_RFC2045(src8, fin_str8, ASCII_BLOCK * 2, strlen(fin_str8), strlen(src8), BASE64_ECODE_OK);

    TEST_RFC2045(src9, fin_str9, ASCII_BLOCK * 2, strlen(fin_str9), strlen(src9), BASE64_ECODE_OK);

    TEST_RFC2045(src10, fin_str10, strlen(fin_str10) + 2, strlen(fin_str10), strlen(src10),

            BASE64_ECODE_OK);

    PASS;

}

static int B64TestVectorsRFC4648(void)

{

    const char *src1 = "";

    const char *fin_str1 = "";

    const char *src2 = "Zg==";

    const char *fin_str2 = "f";

    const char *src3 = "Zm8=";

    const char *fin_str3 = "fo";

    const char *src4 = "Zm9v";

    const char *fin_str4 = "foo";

    const char *src5 = "Zm9vYg==";

    const char *fin_str5 = "foob";

    const char *src6 = "Zm9vYmE=";

    const char *fin_str6 = "fooba";

    const char *src7 = "Zm9vYmFy";

    const char *fin_str7 = "foobar";

    const char *src8 = "Zm 9v Ym Fy";

    const char *fin_str8 = "f";

    const char *src9 = "Zm$9vYm.Fy";

    const char *fin_str9 = "f";

    const char *src10 = "Y21Wd2IzSjBaVzFoYVd4bWNtRjFaRUJoZEc4dVoyOTJMbUYxOmpqcHh4b3Rhb2w%3D";

    const char *fin_str10 = "cmVwb3J0ZW1haWxmcmF1ZEBhdG8uZ292LmF1:jjpxxotaol";

    TEST_RFC4648(src1, fin_str1, ASCII_BLOCK * 2, strlen(fin_str1), strlen(src1), BASE64_ECODE_OK);

    TEST_RFC4648(src2, fin_str2, ASCII_BLOCK * 2, strlen(fin_str2), strlen(src2), BASE64_ECODE_OK);

    TEST_RFC4648(src3, fin_str3, ASCII_BLOCK * 2, strlen(fin_str3), strlen(src3), BASE64_ECODE_OK);

    TEST_RFC4648(src4, fin_str4, ASCII_BLOCK * 2, strlen(fin_str4), strlen(src4), BASE64_ECODE_OK);

    TEST_RFC4648(src5, fin_str5, ASCII_BLOCK * 2, strlen(fin_str5), strlen(src5), BASE64_ECODE_OK);

    TEST_RFC4648(src6, fin_str6, ASCII_BLOCK * 2, strlen(fin_str6), strlen(src6), BASE64_ECODE_OK);

    TEST_RFC4648(src7, fin_str7, ASCII_BLOCK * 2, strlen(fin_str7), strlen(src7), BASE64_ECODE_OK);

    TEST_RFC4648(src8, fin_str8, ASCII_BLOCK * 2, 1 /* f */, 2 /* Zm */, BASE64_ECODE_ERR);

    TEST_RFC4648(src9, fin_str9, ASCII_BLOCK * 2, 1 /* f */, 2 /* Zm */, BASE64_ECODE_ERR);

    TEST_RFC4648(src10, fin_str10, strlen(fin_str10) + 1, strlen(fin_str10), strlen(src10) - 3,

            BASE64_ECODE_ERR);

    PASS;

}

void Base64RegisterTests(void)

{

    UtRegisterTest("B64DecodeCompleteStringWSp", B64DecodeCompleteStringWSp);

    UtRegisterTest("B64DecodeInCompleteStringWSp", B64DecodeInCompleteStringWSp);

    UtRegisterTest("B64DecodeCompleteString", B64DecodeCompleteString);

    UtRegisterTest("B64DecodeInCompleteString", B64DecodeInCompleteString);

    UtRegisterTest("B64DecodeStringBiggerThanBuffer", B64DecodeStringBiggerThanBuffer);

    UtRegisterTest("B64DecodeStringEndingSpaces", B64DecodeStringEndingSpaces);

    UtRegisterTest("B64TestVectorsRFC2045", B64TestVectorsRFC2045);

    UtRegisterTest("B64TestVectorsRFC4648", B64TestVectorsRFC4648);

}

#endif