/*

 * Copyright 1995-2024 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <limits.h>

#include "internal/cryptlib.h"

#include <openssl/evp.h>

#include "crypto/evp.h"

#include "evp_local.h"

static unsigned char conv_ascii2bin(unsigned char a,

                                    const unsigned char *table);

static int evp_encodeblock_int(EVP_ENCODE_CTX *ctx, unsigned char *t,

                               const unsigned char *f, int dlen);

static int evp_decodeblock_int(EVP_ENCODE_CTX *ctx, unsigned char *t,

                               const unsigned char *f, int n);

#ifndef CHARSET_EBCDIC

# define conv_bin2ascii(a, table)       ((table)[(a)&0x3f])

#else

/*

 * We assume that PEM encoded files are EBCDIC files (i.e., printable text

 * files). Convert them here while decoding. When encoding, output is EBCDIC

 * (text) format again. (No need for conversion in the conv_bin2ascii macro,

 * as the underlying textstring data_bin2ascii[] is already EBCDIC)

 */

# define conv_bin2ascii(a, table)       ((table)[(a)&0x3f])

#endif

/*-

 * 64 char lines

 * pad input with 0

 * left over chars are set to =

 * 1 byte  => xx==

 * 2 bytes => xxx=

 * 3 bytes => xxxx

 */

#define BIN_PER_LINE    (64/4*3)

#define CHUNKS_PER_LINE (64/4)

#define CHAR_PER_LINE   (64+1)

static const unsigned char data_bin2ascii[65] =

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/* SRP uses a different base64 alphabet */

static const unsigned char srpdata_bin2ascii[65] =

    "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";

/*-

 * 0xF0 is a EOLN

 * 0xF1 is ignore but next needs to be 0xF0 (for \r\n processing).

 * 0xF2 is EOF

 * 0xE0 is ignore at start of line.

 * 0xFF is error

 */

#define B64_EOLN                0xF0

#define B64_CR                  0xF1

#define B64_EOF                 0xF2

#define B64_WS                  0xE0

#define B64_ERROR               0xFF

#define B64_NOT_BASE64(a)       (((a)|0x13) == 0xF3)

#define B64_BASE64(a)           (!B64_NOT_BASE64(a))

static const unsigned char data_ascii2bin[128] = {

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xE0, 0xF0, 0xFF, 0xFF, 0xF1, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xE0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0x3E, 0xFF, 0xF2, 0xFF, 0x3F,

    0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B,

    0x3C, 0x3D, 0xFF, 0xFF, 0xFF, 0x00, 0xFF, 0xFF,

    0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,

    0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,

    0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,

    0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20,

    0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,

    0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30,

    0x31, 0x32, 0x33, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

};

static const unsigned char srpdata_ascii2bin[128] = {

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xE0, 0xF0, 0xFF, 0xFF, 0xF1, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xE0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xF2, 0x3E, 0x3F,

    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,

    0x08, 0x09, 0xFF, 0xFF, 0xFF, 0x00, 0xFF, 0xFF,

    0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10,

    0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,

    0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20,

    0x21, 0x22, 0x23, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A,

    0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32,

    0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,

    0x3B, 0x3C, 0x3D, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

};

#ifndef CHARSET_EBCDIC

static unsigned char conv_ascii2bin(unsigned char a, const unsigned char *table)

{

    if (a & 0x80)

        return B64_ERROR;

    return table[a];

}

#else

static unsigned char conv_ascii2bin(unsigned char a, const unsigned char *table)

{

    a = os_toascii[a];

    if (a & 0x80)

        return B64_ERROR;

    return table[a];

}

#endif

EVP_ENCODE_CTX *EVP_ENCODE_CTX_new(void)

{

    return OPENSSL_zalloc(sizeof(EVP_ENCODE_CTX));

}

void EVP_ENCODE_CTX_free(EVP_ENCODE_CTX *ctx)

{

    OPENSSL_free(ctx);

}

int EVP_ENCODE_CTX_copy(EVP_ENCODE_CTX *dctx, const EVP_ENCODE_CTX *sctx)

{

    memcpy(dctx, sctx, sizeof(EVP_ENCODE_CTX));

    return 1;

}

int EVP_ENCODE_CTX_num(EVP_ENCODE_CTX *ctx)

{

    return ctx->num;

}

void evp_encode_ctx_set_flags(EVP_ENCODE_CTX *ctx, unsigned int flags)

{

    ctx->flags = flags;

}

void EVP_EncodeInit(EVP_ENCODE_CTX *ctx)

{

    ctx->length = 48;

    ctx->num = 0;

    ctx->line_num = 0;

    ctx->flags = 0;

}

int EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,

                      const unsigned char *in, int inl)

{

    int i, j;

    size_t total = 0;

    *outl = 0;

    if (inl <= 0)

        return 0;

    OPENSSL_assert(ctx->length <= (int)sizeof(ctx->enc_data));

    if (ctx->length - ctx->num > inl) {

        memcpy(&(ctx->enc_data[ctx->num]), in, inl);

        ctx->num += inl;

        return 1;

    }

    if (ctx->num != 0) {

        i = ctx->length - ctx->num;

        memcpy(&(ctx->enc_data[ctx->num]), in, i);

        in += i;

        inl -= i;

        j = evp_encodeblock_int(ctx, out, ctx->enc_data, ctx->length);

        ctx->num = 0;

        out += j;

        total = j;

        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0) {

            *(out++) = '\n';

            total++;

        }

        *out = '\0';

    }

    while (inl >= ctx->length && total <= INT_MAX) {

        j = evp_encodeblock_int(ctx, out, in, ctx->length);

        in += ctx->length;

        inl -= ctx->length;

        out += j;

        total += j;

        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0) {

            *(out++) = '\n';

            total++;

        }

        *out = '\0';

    }

    if (total > INT_MAX) {

        /* Too much output data! */

        *outl = 0;

        return 0;

    }

    if (inl != 0)

        memcpy(&(ctx->enc_data[0]), in, inl);

    ctx->num = inl;

    *outl = total;

    return 1;

}

void EVP_EncodeFinal(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl)

{

    unsigned int ret = 0;

    if (ctx->num != 0) {

        ret = evp_encodeblock_int(ctx, out, ctx->enc_data, ctx->num);

        if ((ctx->flags & EVP_ENCODE_CTX_NO_NEWLINES) == 0)

            out[ret++] = '\n';

        out[ret] = '\0';

        ctx->num = 0;

    }

    *outl = ret;

}

static int evp_encodeblock_int(EVP_ENCODE_CTX *ctx, unsigned char *t,

                               const unsigned char *f, int dlen)

{

    int i, ret = 0;

    unsigned long l;

    const unsigned char *table;

    if (ctx != NULL && (ctx->flags & EVP_ENCODE_CTX_USE_SRP_ALPHABET) != 0)

        table = srpdata_bin2ascii;

    else

        table = data_bin2ascii;

    for (i = dlen; i > 0; i -= 3) {

        if (i >= 3) {

            l = (((unsigned long)f[0]) << 16L) |

                (((unsigned long)f[1]) << 8L) | f[2];

            *(t++) = conv_bin2ascii(l >> 18L, table);

            *(t++) = conv_bin2ascii(l >> 12L, table);

            *(t++) = conv_bin2ascii(l >> 6L, table);

            *(t++) = conv_bin2ascii(l, table);

        } else {

            l = ((unsigned long)f[0]) << 16L;

            if (i == 2)

                l |= ((unsigned long)f[1] << 8L);

            *(t++) = conv_bin2ascii(l >> 18L, table);

            *(t++) = conv_bin2ascii(l >> 12L, table);

            *(t++) = (i == 1) ? '=' : conv_bin2ascii(l >> 6L, table);

            *(t++) = '=';

        }

        ret += 4;

        f += 3;

    }

    *t = '\0';

    return ret;

}

int EVP_EncodeBlock(unsigned char *t, const unsigned char *f, int dlen)

{

    return evp_encodeblock_int(NULL, t, f, dlen);

}

void EVP_DecodeInit(EVP_ENCODE_CTX *ctx)

{

    /* Only ctx->num and ctx->flags are used during decoding. */

    ctx->num = 0;

    ctx->length = 0;

    ctx->line_num = 0;

    ctx->flags = 0;

}

/*-

 * -1 for error

 *  0 for last line

 *  1 for full line

 *

 * Note: even though EVP_DecodeUpdate attempts to detect and report end of

 * content, the context doesn't currently remember it and will accept more data

 * in the next call. Therefore, the caller is responsible for checking and

 * rejecting a 0 return value in the middle of content.

 *

 * Note: even though EVP_DecodeUpdate has historically tried to detect end of

 * content based on line length, this has never worked properly. Therefore,

 * we now return 0 when one of the following is true:

 *   - Padding or B64_EOF was detected and the last block is complete.

 *   - Input has zero-length.

 * -1 is returned if:

 *   - Invalid characters are detected.

 *   - There is extra trailing padding, or data after padding.

 *   - B64_EOF is detected after an incomplete base64 block.

 */

int EVP_DecodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,

                     const unsigned char *in, int inl)

{

    int seof = 0, eof = 0, rv = -1, ret = 0, i, v, tmp, n, decoded_len;

    unsigned char *d;

    const unsigned char *table;

    n = ctx->num;

    d = ctx->enc_data;

    if (n > 0 && d[n - 1] == '=') {

        eof++;

        if (n > 1 && d[n - 2] == '=')

            eof++;

    }

     /* Legacy behaviour: an empty input chunk signals end of input. */

    if (inl == 0) {

        rv = 0;

        goto end;

    }

    if ((ctx->flags & EVP_ENCODE_CTX_USE_SRP_ALPHABET) != 0)

        table = srpdata_ascii2bin;

    else

        table = data_ascii2bin;

    for (i = 0; i < inl; i++) {

        tmp = *(in++);

        v = conv_ascii2bin(tmp, table);

        if (v == B64_ERROR) {

            rv = -1;

            goto end;

        }

        if (tmp == '=') {

            eof++;

        } else if (eof > 0 && B64_BASE64(v)) {

            /* More data after padding. */

            rv = -1;

            goto end;

        }

        if (eof > 2) {

            rv = -1;

            goto end;

        }

        if (v == B64_EOF) {

            seof = 1;

            goto tail;

        }

        /* Only save valid base64 characters. */

        if (B64_BASE64(v)) {

            if (n >= 64) {

                /*

                 * We increment n once per loop, and empty the buffer as soon as

                 * we reach 64 characters, so this can only happen if someone's

                 * manually messed with the ctx. Refuse to write any more data.

                 */

                rv = -1;

                goto end;

            }

            OPENSSL_assert(n < (int)sizeof(ctx->enc_data));

            d[n++] = tmp;

        }

        if (n == 64) {

            decoded_len = evp_decodeblock_int(ctx, out, d, n);

            n = 0;

            if (decoded_len < 0 || eof > decoded_len) {

                rv = -1;

                goto end;

            }

            ret += decoded_len - eof;

            out += decoded_len - eof;

        }

    }

    /*

     * Legacy behaviour: if the current line is a full base64-block (i.e., has

     * 0 mod 4 base64 characters), it is processed immediately. We keep this

     * behaviour as applications may not be calling EVP_DecodeFinal properly.

     */

tail:

    if (n > 0) {

        if ((n & 3) == 0) {

            decoded_len = evp_decodeblock_int(ctx, out, d, n);

            n = 0;

            if (decoded_len < 0 || eof > decoded_len) {

                rv = -1;

                goto end;

            }

            ret += (decoded_len - eof);

        } else if (seof) {

            /* EOF in the middle of a base64 block. */

            rv = -1;

            goto end;

        }

    }

    rv = seof || (n == 0 && eof) ? 0 : 1;

end:

    /* Legacy behaviour. This should probably rather be zeroed on error. */

    *outl = ret;

    ctx->num = n;

    return rv;

}

static int evp_decodeblock_int(EVP_ENCODE_CTX *ctx, unsigned char *t,

                               const unsigned char *f, int n)

{

    int i, ret = 0, a, b, c, d;

    unsigned long l;

    const unsigned char *table;

    if (ctx != NULL && (ctx->flags & EVP_ENCODE_CTX_USE_SRP_ALPHABET) != 0)

        table = srpdata_ascii2bin;

    else

        table = data_ascii2bin;

    /* trim whitespace from the start of the line. */

    while ((n > 0) && (conv_ascii2bin(*f, table) == B64_WS)) {

        f++;

        n--;

    }

    /*

     * strip off stuff at the end of the line ascii2bin values B64_WS,

     * B64_EOLN, B64_EOLN and B64_EOF

     */

    while ((n > 3) && (B64_NOT_BASE64(conv_ascii2bin(f[n - 1], table))))

        n--;

    if (n % 4 != 0)

        return -1;

    for (i = 0; i < n; i += 4) {

        a = conv_ascii2bin(*(f++), table);

        b = conv_ascii2bin(*(f++), table);

        c = conv_ascii2bin(*(f++), table);

        d = conv_ascii2bin(*(f++), table);

        if ((a | b | c | d) & 0x80)

            return -1;

        l = ((((unsigned long)a) << 18L) |

             (((unsigned long)b) << 12L) |

             (((unsigned long)c) << 6L) | (((unsigned long)d)));

        *(t++) = (unsigned char)(l >> 16L) & 0xff;

        *(t++) = (unsigned char)(l >> 8L) & 0xff;

        *(t++) = (unsigned char)(l) & 0xff;

        ret += 3;

    }

    return ret;

}

int EVP_DecodeBlock(unsigned char *t, const unsigned char *f, int n)

{

    return evp_decodeblock_int(NULL, t, f, n);

}

int EVP_DecodeFinal(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl)

{

    int i;

    *outl = 0;

    if (ctx->num != 0) {

        i = evp_decodeblock_int(ctx, out, ctx->enc_data, ctx->num);

        if (i < 0)

            return -1;

        ctx->num = 0;

        *outl = i;

        return 1;

    } else

        return 1;

}