bio_b64.c

Go to the documentation of this file.

/* crypto/evp/bio_b64.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * 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 ([email protected]).
 * 
 * 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 ([email protected])"
 *    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 ([email protected])"
 * 
 * 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 "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=(BIO_B64_CTX *)OPENSSL_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);
    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;
            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)
                {
                /* 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;

#if 0
            jj=(i>>2)<<2;
#else
            jj = i & ~3; /* process per 4 */
#endif
            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));
    }