/* $OpenBSD: bio_b64.c,v 1.29 2024/04/09 13:52:41 beck Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include <openssl/buffer.h>
#include <openssl/evp.h>

#include "bio_local.h"
#include "evp_local.h"

static int b64_write(BIO *h, const char *buf, int num);
static int b64_read(BIO *h, char *buf, int size);
static int b64_puts(BIO *h, const char *str);
/*static int b64_gets(BIO *h, char *str, int size); */
static long b64_ctrl(BIO *h, int cmd, long arg1, void *arg2);
static int b64_new(BIO *h);
static int b64_free(BIO *data);
static long b64_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fp);
#define B64_BLOCK_SIZE  1024
#define B64_BLOCK_SIZE2 768
#define B64_NONE        0
#define B64_ENCODE      1
#define B64_DECODE      2

typedef struct b64_struct {
        /*BIO *bio; moved to the BIO structure */
        int buf_len;
        int buf_off;
        int tmp_len;            /* used to find the start when decoding */
        int tmp_nl;             /* If true, scan until '\n' */
        int encode;
        int start;              /* have we started decoding yet? */
        int cont;               /* <= 0 when finished */
        EVP_ENCODE_CTX base64;
        char buf[EVP_ENCODE_LENGTH(B64_BLOCK_SIZE) + 10];
        char tmp[B64_BLOCK_SIZE];
} BIO_B64_CTX;

static const BIO_METHOD methods_b64 = {
        .type = BIO_TYPE_BASE64,
        .name = "base64 encoding",
        .bwrite = b64_write,
        .bread = b64_read,
        .bputs = b64_puts,
        .ctrl = b64_ctrl,
        .create = b64_new,
        .destroy = b64_free,
        .callback_ctrl = b64_callback_ctrl
};

const BIO_METHOD *
BIO_f_base64(void)
{
        return (&methods_b64);
}
LCRYPTO_ALIAS(BIO_f_base64);

static int
b64_new(BIO *bi)
{
        BIO_B64_CTX *ctx;

        ctx = malloc(sizeof(BIO_B64_CTX));
        if (ctx == NULL)
                return (0);

        ctx->buf_len = 0;
        ctx->tmp_len = 0;
        ctx->tmp_nl = 0;
        ctx->buf_off = 0;
        ctx->cont = 1;
        ctx->start = 1;
        ctx->encode = 0;

        bi->init = 1;
        bi->ptr = (char *)ctx;
        bi->flags = 0;
        bi->num = 0;
        return (1);
}

static int
b64_free(BIO *a)
{
        if (a == NULL)
                return (0);
        free(a->ptr);
        a->ptr = NULL;
        a->init = 0;
        a->flags = 0;
        return (1);
}

static int
b64_read(BIO *b, char *out, int outl)
{
        int ret = 0, i, ii, j, k, x, n, num, ret_code = 0;
        BIO_B64_CTX *ctx;
        unsigned char *p, *q;

        if (out == NULL)
                return (0);
        ctx = (BIO_B64_CTX *)b->ptr;

        if ((ctx == NULL) || (b->next_bio == NULL))
                return (0);

        BIO_clear_retry_flags(b);

        if (ctx->encode != B64_DECODE) {
                ctx->encode = B64_DECODE;
                ctx->buf_len = 0;
                ctx->buf_off = 0;
                ctx->tmp_len = 0;
                EVP_DecodeInit(&(ctx->base64));
        }

        /* First check if there are bytes decoded/encoded */
        if (ctx->buf_len > 0) {
                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                i = ctx->buf_len - ctx->buf_off;
                if (i > outl)
                        i = outl;
                OPENSSL_assert(ctx->buf_off + i < (int)sizeof(ctx->buf));
                memcpy(out, &(ctx->buf[ctx->buf_off]), i);
                ret = i;
                out += i;
                outl -= i;
                ctx->buf_off += i;
                if (ctx->buf_len == ctx->buf_off) {
                        ctx->buf_len = 0;
                        ctx->buf_off = 0;
                }
        }

        /* At this point, we have room of outl bytes and an empty
         * buffer, so we should read in some more. */

        ret_code = 0;
        while (outl > 0) {
                if (ctx->cont <= 0)
                        break;

                i = BIO_read(b->next_bio, &(ctx->tmp[ctx->tmp_len]),
                    B64_BLOCK_SIZE - ctx->tmp_len);

                if (i <= 0) {
                        ret_code = i;

                        /* Should we continue next time we are called? */
                        if (!BIO_should_retry(b->next_bio)) {
                                ctx->cont = i;
                                /* If buffer empty break */
                                if (ctx->tmp_len == 0)
                                        break;
                                /* Fall through and process what we have */
                                else
                                        i = 0;
                        }
                        /* else we retry and add more data to buffer */
                        else
                                break;
                }
                i += ctx->tmp_len;
                ctx->tmp_len = i;

                /* We need to scan, a line at a time until we
                 * have a valid line if we are starting. */
                if (ctx->start && (BIO_get_flags(b) & BIO_FLAGS_BASE64_NO_NL)) {
                        /* ctx->start=1; */
                        ctx->tmp_len = 0;
                } else if (ctx->start) {
                        q = p =(unsigned char *)ctx->tmp;
                        num = 0;
                        for (j = 0; j < i; j++) {
                                if (*(q++) != '\n')
                                        continue;

                                /* due to a previous very long line,
                                 * we need to keep on scanning for a '\n'
                                 * before we even start looking for
                                 * base64 encoded stuff. */
                                if (ctx->tmp_nl) {
                                        p = q;
                                        ctx->tmp_nl = 0;
                                        continue;
                                }

                                k = EVP_DecodeUpdate(&(ctx->base64),
                                    (unsigned char *)ctx->buf,
                                    &num, p, q - p);
                                if ((k <= 0) && (num == 0) && (ctx->start))
                                        EVP_DecodeInit(&ctx->base64);
                                else {
                                        if (p != (unsigned char *)
                                                &(ctx->tmp[0])) {
                                                i -= (p - (unsigned char *)
                                                &(ctx->tmp[0]));
                                                for (x = 0; x < i; x++)
                                                        ctx->tmp[x] = p[x];
                                        }
                                        EVP_DecodeInit(&ctx->base64);
                                        ctx->start = 0;
                                        break;
                                }
                                p = q;
                        }

                        /* we fell off the end without starting */
                        if ((j == i) && (num == 0)) {
                                /* Is this is one long chunk?, if so, keep on
                                 * reading until a new line. */
                                if (p == (unsigned char *)&(ctx->tmp[0])) {
                                        /* Check buffer full */
                                        if (i == B64_BLOCK_SIZE) {
                                                ctx->tmp_nl = 1;
                                                ctx->tmp_len = 0;
                                        }
                                }
                                else if (p != q) /* finished on a '\n' */
                                {
                                        n = q - p;
                                        for (ii = 0; ii < n; ii++)
                                                ctx->tmp[ii] = p[ii];
                                        ctx->tmp_len = n;
                                }
                                /* else finished on a '\n' */
                                continue;
                        } else {
                                ctx->tmp_len = 0;
                        }
                } else if ((i < B64_BLOCK_SIZE) && (ctx->cont > 0)) {
                        /* If buffer isn't full and we can retry then
                         * restart to read in more data.
                         */
                        continue;
                }

                if (BIO_get_flags(b) & BIO_FLAGS_BASE64_NO_NL) {
                        int z, jj;

                        jj = i & ~3; /* process per 4 */
                        z = EVP_DecodeBlock((unsigned char *)ctx->buf,
                            (unsigned char *)ctx->tmp, jj);
                        if (jj > 2) {
                                if (ctx->tmp[jj-1] == '=') {
                                        z--;
                                        if (ctx->tmp[jj-2] == '=')
                                                z--;
                                }
                        }
                        /* z is now number of output bytes and jj is the
                         * number consumed */
                        if (jj != i) {
                                memmove(ctx->tmp, &ctx->tmp[jj], i - jj);
                                ctx->tmp_len = i - jj;
                        }
                        ctx->buf_len = 0;
                        if (z > 0) {
                                ctx->buf_len = z;
                        }
                        i = z;
                } else {
                        i = EVP_DecodeUpdate(&(ctx->base64),
                            (unsigned char *)ctx->buf, &ctx->buf_len,
                            (unsigned char *)ctx->tmp, i);
                        ctx->tmp_len = 0;
                }
                ctx->buf_off = 0;
                if (i < 0) {
                        ret_code = 0;
                        ctx->buf_len = 0;
                        break;
                }

                if (ctx->buf_len <= outl)
                        i = ctx->buf_len;
                else
                        i = outl;

                memcpy(out, ctx->buf, i);
                ret += i;
                ctx->buf_off = i;
                if (ctx->buf_off == ctx->buf_len) {
                        ctx->buf_len = 0;
                        ctx->buf_off = 0;
                }
                outl -= i;
                out += i;
        }
        /* BIO_clear_retry_flags(b); */
        BIO_copy_next_retry(b);
        return ((ret == 0) ? ret_code : ret);
}

static int
b64_write(BIO *b, const char *in, int inl)
{
        int ret = 0;
        int n;
        int i;
        BIO_B64_CTX *ctx;

        ctx = (BIO_B64_CTX *)b->ptr;
        BIO_clear_retry_flags(b);

        if (ctx->encode != B64_ENCODE) {
                ctx->encode = B64_ENCODE;
                ctx->buf_len = 0;
                ctx->buf_off = 0;
                ctx->tmp_len = 0;
                EVP_EncodeInit(&(ctx->base64));
        }

        OPENSSL_assert(ctx->buf_off < (int)sizeof(ctx->buf));
        OPENSSL_assert(ctx->buf_len <= (int)sizeof(ctx->buf));
        OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
        n = ctx->buf_len - ctx->buf_off;
        while (n > 0) {
                i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);
                if (i <= 0) {
                        BIO_copy_next_retry(b);
                        return (i);
                }
                OPENSSL_assert(i <= n);
                ctx->buf_off += i;
                OPENSSL_assert(ctx->buf_off <= (int)sizeof(ctx->buf));
                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                n -= i;
        }
        /* at this point all pending data has been written */
        ctx->buf_off = 0;
        ctx->buf_len = 0;

        if ((in == NULL) || (inl <= 0))
                return (0);

        while (inl > 0) {
                n = (inl > B64_BLOCK_SIZE) ? B64_BLOCK_SIZE : inl;

                if (BIO_get_flags(b) & BIO_FLAGS_BASE64_NO_NL) {
                        if (ctx->tmp_len > 0) {
                                OPENSSL_assert(ctx->tmp_len <= 3);
                                n = 3 - ctx->tmp_len;
                                /* There's a theoretical possibility for this */
                                if (n > inl)
                                        n = inl;
                                memcpy(&(ctx->tmp[ctx->tmp_len]), in, n);
                                ctx->tmp_len += n;
                                ret += n;
                                if (ctx->tmp_len < 3)
                                        break;
                                ctx->buf_len = EVP_EncodeBlock(
                                    (unsigned char *)ctx->buf,
                                    (unsigned char *)ctx->tmp, ctx->tmp_len);
                                OPENSSL_assert(ctx->buf_len <=
                                    (int)sizeof(ctx->buf));
                                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                                /* Since we're now done using the temporary
                                   buffer, the length should be 0'd */
                                ctx->tmp_len = 0;
                        } else {
                                if (n < 3) {
                                        memcpy(ctx->tmp, in, n);
                                        ctx->tmp_len = n;
                                        ret += n;
                                        break;
                                }
                                n -= n % 3;
                                ctx->buf_len = EVP_EncodeBlock(
                                    (unsigned char *)ctx->buf,
                                    (const unsigned char *)in, n);
                                OPENSSL_assert(ctx->buf_len <=
                                    (int)sizeof(ctx->buf));
                                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                                ret += n;
                        }
                } else {
                        if (!EVP_EncodeUpdate(&(ctx->base64),
                            (unsigned char *)ctx->buf, &ctx->buf_len,
                            (unsigned char *)in, n))
                                return ((ret == 0) ? -1 : ret);
                        OPENSSL_assert(ctx->buf_len <= (int)sizeof(ctx->buf));
                        OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                        ret += n;
                }
                inl -= n;
                in += n;

                ctx->buf_off = 0;
                n = ctx->buf_len;
                while (n > 0) {
                        i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);
                        if (i <= 0) {
                                BIO_copy_next_retry(b);
                                return ((ret == 0) ? i : ret);
                        }
                        OPENSSL_assert(i <= n);
                        n -= i;
                        ctx->buf_off += i;
                        OPENSSL_assert(ctx->buf_off <= (int)sizeof(ctx->buf));
                        OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                }
                ctx->buf_len = 0;
                ctx->buf_off = 0;
        }
        return (ret);
}

static long
b64_ctrl(BIO *b, int cmd, long num, void *ptr)
{
        BIO_B64_CTX *ctx;
        long ret = 1;
        int i;

        ctx = (BIO_B64_CTX *)b->ptr;

        switch (cmd) {
        case BIO_CTRL_RESET:
                ctx->cont = 1;
                ctx->start = 1;
                ctx->encode = B64_NONE;
                ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_EOF:      /* More to read */
                if (ctx->cont <= 0)
                        ret = 1;
                else
                        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_WPENDING: /* More to write in buffer */
                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                ret = ctx->buf_len - ctx->buf_off;
                if ((ret == 0) && (ctx->encode != B64_NONE) &&
                    (ctx->base64.num != 0))
                        ret = 1;
                else if (ret <= 0)
                        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_PENDING: /* More to read in buffer */
                OPENSSL_assert(ctx->buf_len >= ctx->buf_off);
                ret = ctx->buf_len - ctx->buf_off;
                if (ret <= 0)
                        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;
        case BIO_CTRL_FLUSH:
                /* do a final write */
again:
                while (ctx->buf_len != ctx->buf_off) {
                        i = b64_write(b, NULL, 0);
                        if (i < 0)
                                return i;
                }
                if (BIO_get_flags(b) & BIO_FLAGS_BASE64_NO_NL) {
                        if (ctx->tmp_len != 0) {
                                ctx->buf_len = EVP_EncodeBlock(
                                    (unsigned char *)ctx->buf,
                                    (unsigned char *)ctx->tmp,
                                    ctx->tmp_len);
                                ctx->buf_off = 0;
                                ctx->tmp_len = 0;
                                goto again;
                        }
                } else if (ctx->encode != B64_NONE && ctx->base64.num != 0) {
                        ctx->buf_off = 0;
                        EVP_EncodeFinal(&(ctx->base64),
                            (unsigned char *)ctx->buf,
                            &(ctx->buf_len));
                        /* push out the bytes */
                        goto again;
                }
                /* Finally flush the underlying BIO */
                ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;

        case BIO_C_DO_STATE_MACHINE:
                BIO_clear_retry_flags(b);
                ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                BIO_copy_next_retry(b);
                break;

        case BIO_CTRL_DUP:
                break;
        case BIO_CTRL_INFO:
        case BIO_CTRL_GET:
        case BIO_CTRL_SET:
        default:
                ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
                break;
        }
        return (ret);
}

static long
b64_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
{
        long ret = 1;

        if (b->next_bio == NULL)
                return (0);
        switch (cmd) {
        default:
                ret = BIO_callback_ctrl(b->next_bio, cmd, fp);
                break;
        }
        return (ret);
}

static int
b64_puts(BIO *b, const char *str)
{
        return b64_write(b, str, strlen(str));
}