/*

 * Copyright 1995-2026 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 <errno.h>

#include "internal/cryptlib.h"

#include <openssl/buffer.h>

#include <openssl/evp.h>

#include "internal/bio.h"

#include "crypto/evp.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 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;

    unsigned char buf[EVP_ENCODE_LENGTH(B64_BLOCK_SIZE) + 10];

    unsigned char tmp[B64_BLOCK_SIZE];

    unsigned char *encoded_buf;

    size_t encoded_buf_len;

} BIO_B64_CTX;

static const BIO_METHOD methods_b64 = {

    BIO_TYPE_BASE64,

    "base64 encoding",

    bwrite_conv,

    b64_write,

    bread_conv,

    b64_read,

    b64_puts,

    NULL, /* b64_gets, */

    b64_ctrl,

    b64_new,

    b64_free,

    b64_callback_ctrl,

};

const BIO_METHOD *BIO_f_base64(void)

{

    return &methods_b64;

}

static int b64_new(BIO *bi)

{

    BIO_B64_CTX *ctx;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)

        return 0;

    ctx->cont = 1;

    ctx->start = 1;

    ctx->encoded_buf = NULL;

    ctx->encoded_buf_len = 0;

    ctx->base64 = EVP_ENCODE_CTX_new();

    if (ctx->base64 == NULL) {

        OPENSSL_free(ctx);

        return 0;

    }

    BIO_set_data(bi, ctx);

    BIO_set_init(bi, 1);

    return 1;

}

static int b64_free(BIO *a)

{

    BIO_B64_CTX *ctx;

    if (a == NULL)

        return 0;

    ctx = BIO_get_data(a);

    if (ctx == NULL)

        return 0;

    OPENSSL_free(ctx->encoded_buf);

    ctx->encoded_buf = NULL;

    ctx->encoded_buf_len = 0;

    EVP_ENCODE_CTX_free(ctx->base64);

    OPENSSL_free(ctx);

    BIO_set_data(a, NULL);

    BIO_set_init(a, 0);

    return 1;

}

/*

 * Unless `BIO_FLAGS_BASE64_NO_NL` is set, this BIO ignores leading lines that

 * aren't exclusively composed of valid Base64 characters (followed by <CRLF>

 * or <LF>).  Once a valid Base64 line is found, `ctx->start` is set to 0 and

 * lines are processed until EOF or the first line that contains invalid Base64

 * characters.  In a nod to PEM, lines that start with a '-' (hyphen) are

 * treated as a soft EOF, rather than an error.

 */

static int b64_read(BIO *b, char *out, int outl)

{

    int ret = 0, i, ii, j, k, x, n, num, ret_code;

    BIO_B64_CTX *ctx;

    unsigned char *p, *q;

    BIO *next;

    if (out == NULL)

        return 0;

    ctx = (BIO_B64_CTX *)BIO_get_data(b);

    next = BIO_next(b);

    if (ctx == NULL || next == 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 buffered bytes already decoded */

    if (ctx->buf_len > 0) {

        if (!ossl_assert(ctx->buf_len >= ctx->buf_off)) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        i = ctx->buf_len - ctx->buf_off;

        if (i > outl)

            i = outl;

        if (!ossl_assert(ctx->buf_off + i < (int)sizeof(ctx->buf))) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        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;

        }

    }

    /* Restore any non-retriable error condition (ctx->cont < 0) */

    ret_code = ctx->cont < 0 ? ctx->cont : 0;

    /*

     * At this point, we have room of outl bytes and an either an empty buffer,

     * or outl == 0, so we'll attempt to read in some more.

     */

    while (outl > 0) {

        int again = ctx->cont;

        if (again <= 0)

            break;

        i = BIO_read(next, &(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(next)) {

                /* Incomplete final Base64 chunk in the decoder is an error */

                if (ctx->tmp_len == 0) {

                    if (EVP_DecodeFinal(ctx->base64, NULL, &num) < 0)

                        ret_code = -1;

                    EVP_DecodeInit(ctx->base64);

                }

                ctx->cont = ret_code;

            }

            if (ctx->tmp_len == 0)

                break;

            /* Fall through and process what we have */

            i = 0;

            /* But don't loop to top-up even if the buffer is not full! */

            again = 0;

        }

        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) != 0) {

            ctx->tmp_len = 0;

        } else if (ctx->start) {

            q = p = 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, ctx->buf, &num, p, (int)(q - p));

                EVP_DecodeInit(ctx->base64);

                if (k <= 0 && num == 0) {

                    p = q;

                    continue;

                }

                ctx->start = 0;

                if (p != ctx->tmp) {

                    i -= (int)(p - ctx->tmp);

                    for (x = 0; x < i; x++)

                        ctx->tmp[x] = p[x];

                }

                break;

            }

            /* we fell off the end without starting */

            if (ctx->start) {

                /*

                 * Is this is one long chunk?, if so, keep on reading until a

                 * new line.

                 */

                if (p == ctx->tmp) {

                    /* Check buffer full */

                    if (i == B64_BLOCK_SIZE) {

                        ctx->tmp_nl = 1;

                        ctx->tmp_len = 0;

                    }

                } else if (p != q) {

                    /* Retain partial line at end of buffer */

                    n = (int)(q - p);

                    for (ii = 0; ii < n; ii++)

                        ctx->tmp[ii] = p[ii];

                    ctx->tmp_len = n;

                } else {

                    /* All we have is newline terminated non-start data */

                    ctx->tmp_len = 0;

                }

                /*

                 * Try to read more if possible, otherwise we can't make

                 * progress unless the underlying BIO is retriable and may

                 * produce more data next time we're called.

                 */

                if (again > 0)

                    continue;

                else

                    break;

            } else {

                ctx->tmp_len = 0;

            }

        } else if (i < B64_BLOCK_SIZE && again > 0) {

            /*

             * If buffer isn't full and we can retry then restart to read in

             * more data.

             */

            continue;

        }

        i = EVP_DecodeUpdate(ctx->base64, ctx->buf, &ctx->buf_len,

            ctx->tmp, i);

        ctx->tmp_len = 0;

        /*

         * If eof or an error was signalled, then the condition

         * 'ctx->cont <= 0' will prevent b64_read() from reading

         * more data on subsequent calls. This assignment was

         * deleted accidentally in commit 5562cfaca4f3.

         */

        ctx->cont = i;

        ctx->buf_off = 0;

        if (i < 0) {

            ret_code = ctx->start ? 0 : i;

            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_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;

    BIO *next;

    size_t encoded_length;

    unsigned char *encoded;

    int n_bytes_enc;

    ctx = (BIO_B64_CTX *)BIO_get_data(b);

    next = BIO_next(b);

    if (ctx == NULL || next == NULL)

        return 0;

    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);

        if (BIO_get_flags(b) & BIO_FLAGS_BASE64_NO_NL)

            evp_encode_ctx_set_flags(ctx->base64, EVP_ENCODE_CTX_NO_NEWLINES);

    }

    if (!ossl_assert(ctx->buf_off < (int)sizeof(ctx->buf))) {

        ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

        return -1;

    }

    if (!ossl_assert(ctx->buf_len <= (int)sizeof(ctx->buf))) {

        ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

        return -1;

    }

    if (!ossl_assert(ctx->buf_len >= ctx->buf_off)) {

        ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

        return -1;

    }

    n = ctx->buf_len - ctx->buf_off;

    while (n > 0) {

        i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);

        if (i <= 0) {

            BIO_copy_next_retry(b);

            return i;

        }

        ctx->buf_off += i;

        if (!ossl_assert(ctx->buf_off <= (int)sizeof(ctx->buf))) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        if (!ossl_assert(ctx->buf_len >= ctx->buf_off)) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        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;

    encoded_length = EVP_ENCODE_LENGTH(inl);

    if (encoded_length > SIZE_MAX / 2) {

        ERR_raise(ERR_LIB_BIO, BIO_R_LENGTH_TOO_LONG);

        return -1;

    }

    if (ctx->encoded_buf == NULL || encoded_length > ctx->encoded_buf_len) {

        OPENSSL_free(ctx->encoded_buf);

        ctx->encoded_buf = OPENSSL_malloc(encoded_length);

        if (ctx->encoded_buf == NULL) {

            ERR_raise(ERR_LIB_BIO, ERR_R_MALLOC_FAILURE);

            return -1;

        }

        ctx->encoded_buf_len = encoded_length;

    }

    encoded = ctx->encoded_buf;

    if (encoded == NULL) {

        ERR_raise(ERR_LIB_BIO, ERR_R_MALLOC_FAILURE);

        return -1;

    }

    n_bytes_enc = 0;

    if (!EVP_EncodeUpdate(ctx->base64, encoded, &n_bytes_enc,

            (unsigned char *)in, inl)) {

        return -1;

    }

    ret += inl;

    i = BIO_write(next, encoded, n_bytes_enc);

    if (i <= 0)

        BIO_copy_next_retry(b);

    return ret;

}

static long b64_ctrl(BIO *b, int cmd, long num, void *ptr)

{

    BIO_B64_CTX *ctx;

    long ret = 1;

    int i;

    BIO *next;

    ctx = (BIO_B64_CTX *)BIO_get_data(b);

    next = BIO_next(b);

    /*

     * If there is no ctx or no next BIO, BIO_read() returns 0, which means EOF.

     * BIO_eof() should return 1 in this case.

     */

    if (ctx == NULL || next == NULL)

        return cmd == BIO_CTRL_EOF;

    switch (cmd) {

    case BIO_CTRL_RESET:

        ctx->cont = 1;

        ctx->start = 1;

        ctx->encode = B64_NONE;

        ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_EOF: /* More to read */

        if (ctx->cont <= 0)

            ret = 1;

        else

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_WPENDING: /* More to write in buffer */

        if (!ossl_assert(ctx->buf_len >= ctx->buf_off)) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        ret = ctx->buf_len - ctx->buf_off;

        if (ret == 0 && ctx->encode != B64_NONE

            && EVP_ENCODE_CTX_num(ctx->base64) != 0)

            ret = 1;

        else if (ret <= 0)

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_PENDING: /* More to read in buffer */

        if (!ossl_assert(ctx->buf_len >= ctx->buf_off)) {

            ERR_raise(ERR_LIB_BIO, ERR_R_INTERNAL_ERROR);

            return -1;

        }

        ret = ctx->buf_len - ctx->buf_off;

        if (ret <= 0)

            ret = BIO_ctrl(next, cmd, num, ptr);

        break;

    case BIO_CTRL_FLUSH:

        if (ctx->encode == B64_ENCODE) {

            /* do a final write */

        again:

            while (ctx->buf_len != ctx->buf_off) {

                i = b64_write(b, NULL, 0);

                if (i < 0)

                    return i;

            }

            if (EVP_ENCODE_CTX_num(ctx->base64) != 0) {

                ctx->buf_off = 0;

                EVP_EncodeFinal(ctx->base64, ctx->buf, &(ctx->buf_len));

                /* push out the bytes */

                goto again;

            }

        }

        /* Finally flush the underlying BIO */

        BIO_clear_retry_flags(b);

        ret = BIO_ctrl(next, cmd, num, ptr);

        BIO_copy_next_retry(b);

        break;

    case BIO_C_DO_STATE_MACHINE:

        BIO_clear_retry_flags(b);

        ret = BIO_ctrl(next, 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(next, cmd, num, ptr);

        break;

    }

    return ret;

}

static long b64_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)

{

    BIO *next = BIO_next(b);

    if (next == NULL)

        return 0;

    return BIO_callback_ctrl(next, cmd, fp);

}

static int b64_puts(BIO *b, const char *str)

{

    size_t len = strlen(str);

    if (len > INT_MAX)

        return -1;

    return b64_write(b, str, (int)len);

}