openssl/crypto/evp/bio_b64.c

/* crypto/evp/bio_b64.c */
/* 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 <stdio.h>
#include <errno.h>
#include "internal/cryptlib.h"
#include <openssl/buffer.h>
#include <openssl/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 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 BIO_METHOD methods_b64 = {
    BIO_TYPE_BASE64, "base64 encoding",
    b64_write,
    b64_read,
    b64_puts,
    NULL,                       /* b64_gets, */
    b64_ctrl,
    b64_new,
    b64_free,
    b64_callback_ctrl,
};

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

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

    ctx = OPENSSL_malloc(sizeof(*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);
    OPENSSL_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 {
            EVP_EncodeUpdate(&(ctx->base64),
                             (unsigned char *)ctx->buf, &ctx->buf_len,
                             (unsigned char *)in, n);
            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));
}