decrepit/bio/base64_bio.c - boringssl - Git at Google

 /* 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 <assert.h>
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>

 #include <openssl/base64.h>
 #include <openssl/bio.h>
 #include <openssl/buffer.h>
 #include <openssl/evp.h>
 #include <openssl/mem.h>

 #include "../../crypto/internal.h"


 #define B64_BLOCK_SIZE 1024
 #define B64_BLOCK_SIZE2 768
 #define B64_NONE 0
 #define B64_ENCODE 1
 #define B64_DECODE 2
 #define EVP_ENCODE_LENGTH(l) (((l+2)/3*4)+(l/48+1)*2+80)

 typedef struct b64_struct {
   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 int b64_new(BIO *bio) {
   BIO_B64_CTX *ctx;

   ctx = OPENSSL_malloc(sizeof(*ctx));
   if (ctx == NULL) {
     return 0;
   }

   OPENSSL_memset(ctx, 0, sizeof(*ctx));

   ctx->cont = 1;
   ctx->start = 1;

   bio->init = 1;
   bio->ptr = (char *)ctx;
   return 1;
 }

 static int b64_free(BIO *bio) {
   if (bio == NULL) {
     return 0;
   }
   OPENSSL_free(bio->ptr);
   bio->ptr = NULL;
   bio->init = 0;
   bio->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;
   uint8_t *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) {
     assert(ctx->buf_len >= ctx->buf_off);
     i = ctx->buf_len - ctx->buf_off;
     if (i > outl) {
       i = outl;
     }
     assert(ctx->buf_off + i < (int)sizeof(ctx->buf));
     OPENSSL_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;
         } else {
           // Fall through and process what we have
           i = 0;
         }
       } else {
         // else we retry and add more data to buffer
         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_test_flags(b, BIO_FLAGS_BASE64_NO_NL))) {
       // ctx->start = 1;
       ctx->tmp_len = 0;
     } else if (ctx->start) {
       q = p = (uint8_t *)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), (uint8_t *)ctx->buf, &num, p,
                              q - p);

         if (k <= 0 && num == 0 && ctx->start) {
           EVP_DecodeInit(&ctx->base64);
         } else {
           if (p != (uint8_t *)&(ctx->tmp[0])) {
             i -= (p - (uint8_t *)&(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 == (uint8_t *)&(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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
       int z, jj;

       jj = i & ~3;  // process per 4
       z = EVP_DecodeBlock((uint8_t *)ctx->buf, (uint8_t *)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) {
         OPENSSL_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), (uint8_t *)ctx->buf,
                            &ctx->buf_len, (uint8_t *)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;
     }

     OPENSSL_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, n, 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));
   }

   assert(ctx->buf_off < (int)sizeof(ctx->buf));
   assert(ctx->buf_len <= (int)sizeof(ctx->buf));
   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;
     }
     assert(i <= n);
     ctx->buf_off += i;
     assert(ctx->buf_off <= (int)sizeof(ctx->buf));
     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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
       if (ctx->tmp_len > 0) {
         assert(ctx->tmp_len <= 3);
         n = 3 - ctx->tmp_len;
         // There's a theoretical possibility of this.
         if (n > inl) {
           n = inl;
         }
         OPENSSL_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((uint8_t *)ctx->buf, (uint8_t *)ctx->tmp,
                                        ctx->tmp_len);
         assert(ctx->buf_len <= (int)sizeof(ctx->buf));
         assert(ctx->buf_len >= ctx->buf_off);

         // Since we're now done using the temporary buffer, the length should
         // be zeroed.
         ctx->tmp_len = 0;
       } else {
         if (n < 3) {
           OPENSSL_memcpy(ctx->tmp, in, n);
           ctx->tmp_len = n;
           ret += n;
           break;
         }
         n -= n % 3;
         ctx->buf_len =
             EVP_EncodeBlock((uint8_t *)ctx->buf, (const uint8_t *)in, n);
         assert(ctx->buf_len <= (int)sizeof(ctx->buf));
         assert(ctx->buf_len >= ctx->buf_off);
         ret += n;
       }
     } else {
       EVP_EncodeUpdate(&(ctx->base64), (uint8_t *)ctx->buf, &ctx->buf_len,
                        (uint8_t *)in, n);
       assert(ctx->buf_len <= (int)sizeof(ctx->buf));
       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;
       }
       assert(i <= n);
       n -= i;
       ctx->buf_off += i;
       assert(ctx->buf_off <= (int)sizeof(ctx->buf));
       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
       assert(ctx->buf_len >= ctx->buf_off);
       ret = ctx->buf_len - ctx->buf_off;
       if ((ret == 0) && (ctx->encode != B64_NONE) && (ctx->base64.data_used != 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
       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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
         if (ctx->tmp_len != 0) {
           ctx->buf_len = EVP_EncodeBlock((uint8_t *)ctx->buf,
                                          (uint8_t *)ctx->tmp, ctx->tmp_len);
           ctx->buf_off = 0;
           ctx->tmp_len = 0;
           goto again;
         }
       } else if (ctx->encode != B64_NONE && ctx->base64.data_used != 0) {
         ctx->buf_off = 0;
         EVP_EncodeFinal(&(ctx->base64), (uint8_t *)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_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 const BIO_METHOD b64_method = {
     BIO_TYPE_BASE64, "base64 encoding", b64_write, b64_read, NULL /* puts */,
     NULL /* gets */, b64_ctrl,          b64_new,   b64_free, b64_callback_ctrl,
 };

 const BIO_METHOD *BIO_f_base64(void) { return &b64_method; }
	/* 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 <assert.h>
	#include <errno.h>
	#include <stdio.h>
	#include <string.h>

	#include <openssl/base64.h>
	#include <openssl/bio.h>
	#include <openssl/buffer.h>
	#include <openssl/evp.h>
	#include <openssl/mem.h>

	#include "../../crypto/internal.h"


	#define B64_BLOCK_SIZE 1024
	#define B64_BLOCK_SIZE2 768
	#define B64_NONE 0
	#define B64_ENCODE 1
	#define B64_DECODE 2
	#define EVP_ENCODE_LENGTH(l) (((l+2)/34)+(l/48+1)2+80)

	typedef struct b64_struct {
	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 int b64_new(BIO *bio) {
	BIO_B64_CTX *ctx;

	ctx = OPENSSL_malloc(sizeof(*ctx));
	if (ctx == NULL) {
	return 0;
	}

	OPENSSL_memset(ctx, 0, sizeof(*ctx));

	ctx->cont = 1;
	ctx->start = 1;

	bio->init = 1;
	bio->ptr = (char *)ctx;
	return 1;
	}

	static int b64_free(BIO *bio) {
	if (bio == NULL) {
	return 0;
	}
	OPENSSL_free(bio->ptr);
	bio->ptr = NULL;
	bio->init = 0;
	bio->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;
	uint8_t 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) {
	assert(ctx->buf_len >= ctx->buf_off);
	i = ctx->buf_len - ctx->buf_off;
	if (i > outl) {
	i = outl;
	}
	assert(ctx->buf_off + i < (int)sizeof(ctx->buf));
	OPENSSL_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;
	} else {
	// Fall through and process what we have
	i = 0;
	}
	} else {
	// else we retry and add more data to buffer
	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_test_flags(b, BIO_FLAGS_BASE64_NO_NL))) {
	// ctx->start = 1;
	ctx->tmp_len = 0;
	} else if (ctx->start) {
	q = p = (uint8_t *)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), (uint8_t *)ctx->buf, &num, p,
	q - p);

	if (k <= 0 && num == 0 && ctx->start) {
	EVP_DecodeInit(&ctx->base64);
	} else {
	if (p != (uint8_t *)&(ctx->tmp[0])) {
	i -= (p - (uint8_t *)&(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 == (uint8_t *)&(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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
	int z, jj;

	jj = i & ~3; // process per 4
	z = EVP_DecodeBlock((uint8_t )ctx->buf, (uint8_t )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) {
	OPENSSL_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), (uint8_t *)ctx->buf,
	&ctx->buf_len, (uint8_t *)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;
	}

	OPENSSL_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, n, 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));
	}

	assert(ctx->buf_off < (int)sizeof(ctx->buf));
	assert(ctx->buf_len <= (int)sizeof(ctx->buf));
	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;
	}
	assert(i <= n);
	ctx->buf_off += i;
	assert(ctx->buf_off <= (int)sizeof(ctx->buf));
	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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
	if (ctx->tmp_len > 0) {
	assert(ctx->tmp_len <= 3);
	n = 3 - ctx->tmp_len;
	// There's a theoretical possibility of this.
	if (n > inl) {
	n = inl;
	}
	OPENSSL_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((uint8_t )ctx->buf, (uint8_t )ctx->tmp,
	ctx->tmp_len);
	assert(ctx->buf_len <= (int)sizeof(ctx->buf));
	assert(ctx->buf_len >= ctx->buf_off);

	// Since we're now done using the temporary buffer, the length should
	// be zeroed.
	ctx->tmp_len = 0;
	} else {
	if (n < 3) {
	OPENSSL_memcpy(ctx->tmp, in, n);
	ctx->tmp_len = n;
	ret += n;
	break;
	}
	n -= n % 3;
	ctx->buf_len =
	EVP_EncodeBlock((uint8_t )ctx->buf, (const uint8_t )in, n);
	assert(ctx->buf_len <= (int)sizeof(ctx->buf));
	assert(ctx->buf_len >= ctx->buf_off);
	ret += n;
	}
	} else {
	EVP_EncodeUpdate(&(ctx->base64), (uint8_t *)ctx->buf, &ctx->buf_len,
	(uint8_t *)in, n);
	assert(ctx->buf_len <= (int)sizeof(ctx->buf));
	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;
	}
	assert(i <= n);
	n -= i;
	ctx->buf_off += i;
	assert(ctx->buf_off <= (int)sizeof(ctx->buf));
	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
	assert(ctx->buf_len >= ctx->buf_off);
	ret = ctx->buf_len - ctx->buf_off;
	if ((ret == 0) && (ctx->encode != B64_NONE) && (ctx->base64.data_used != 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
	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_test_flags(b, BIO_FLAGS_BASE64_NO_NL)) {
	if (ctx->tmp_len != 0) {
	ctx->buf_len = EVP_EncodeBlock((uint8_t *)ctx->buf,
	(uint8_t *)ctx->tmp, ctx->tmp_len);
	ctx->buf_off = 0;
	ctx->tmp_len = 0;
	goto again;
	}
	} else if (ctx->encode != B64_NONE && ctx->base64.data_used != 0) {
	ctx->buf_off = 0;
	EVP_EncodeFinal(&(ctx->base64), (uint8_t *)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_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 const BIO_METHOD b64_method = {
	BIO_TYPE_BASE64, "base64 encoding", b64_write, b64_read, NULL /* puts */,
	NULL /* gets */, b64_ctrl, b64_new, b64_free, b64_callback_ctrl,
	};

	const BIO_METHOD *BIO_f_base64(void) { return &b64_method; }