| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | BIO_f_base64 - base64 BIO filter
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | =for openssl multiple includes
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| 10 |
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| 11 | #include <openssl/bio.h>
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| 12 | #include <openssl/evp.h>
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| 13 |
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| 14 | const BIO_METHOD *BIO_f_base64(void);
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| 15 |
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| 16 | =head1 DESCRIPTION
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| 17 |
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| 18 | BIO_f_base64() returns the base64 BIO method. This is a filter
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| 19 | BIO that base64 encodes any data written through it and decodes
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| 20 | any data read through it.
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| 21 |
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| 22 | Base64 BIOs do not support BIO_gets() or BIO_puts().
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| 23 |
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| 24 | For writing, output is by default divided to lines of length 64
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| 25 | characters and there is always a newline at the end of output.
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| 26 |
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| 27 | For reading, first line should be at most 1024
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| 28 | characters long. If it is longer then it is ignored completely.
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| 29 | Other input lines can be of any length. There must be a newline
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| 30 | at the end of input.
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| 31 |
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| 32 | This behavior can be changed with BIO_FLAGS_BASE64_NO_NL flag.
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| 33 |
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| 34 | BIO_flush() on a base64 BIO that is being written through is
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| 35 | used to signal that no more data is to be encoded: this is used
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| 36 | to flush the final block through the BIO.
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| 37 |
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| 38 | The flag BIO_FLAGS_BASE64_NO_NL can be set with BIO_set_flags().
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| 39 | For writing, it causes all data to be written on one line without
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| 40 | newline at the end.
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| 41 | For reading, it expects the data to be all on one line (with or
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| 42 | without a trailing newline).
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| 43 |
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| 44 | =head1 NOTES
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| 45 |
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| 46 | Because of the format of base64 encoding the end of the encoded
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| 47 | block cannot always be reliably determined.
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| 48 |
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| 49 | =head1 RETURN VALUES
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| 50 |
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| 51 | BIO_f_base64() returns the base64 BIO method.
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| 52 |
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| 53 | =head1 EXAMPLES
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| 54 |
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| 55 | Base64 encode the string "Hello World\n" and write the result
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| 56 | to standard output:
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| 57 |
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| 58 | BIO *bio, *b64;
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| 59 | char message[] = "Hello World \n";
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| 60 |
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| 61 | b64 = BIO_new(BIO_f_base64());
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| 62 | bio = BIO_new_fp(stdout, BIO_NOCLOSE);
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| 63 | BIO_push(b64, bio);
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| 64 | BIO_write(b64, message, strlen(message));
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| 65 | BIO_flush(b64);
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| 66 |
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| 67 | BIO_free_all(b64);
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| 68 |
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| 69 | Read Base64 encoded data from standard input and write the decoded
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| 70 | data to standard output:
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| 71 |
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| 72 | BIO *bio, *b64, *bio_out;
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| 73 | char inbuf[512];
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| 74 | int inlen;
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| 75 |
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| 76 | b64 = BIO_new(BIO_f_base64());
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| 77 | bio = BIO_new_fp(stdin, BIO_NOCLOSE);
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| 78 | bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
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| 79 | BIO_push(b64, bio);
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| 80 | while ((inlen = BIO_read(b64, inbuf, 512)) > 0)
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| 81 | BIO_write(bio_out, inbuf, inlen);
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| 82 |
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| 83 | BIO_flush(bio_out);
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| 84 | BIO_free_all(b64);
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| 85 |
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| 86 | =head1 BUGS
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| 87 |
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| 88 | The ambiguity of EOF in base64 encoded data can cause additional
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| 89 | data following the base64 encoded block to be misinterpreted.
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| 90 |
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| 91 | There should be some way of specifying a test that the BIO can perform
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| 92 | to reliably determine EOF (for example a MIME boundary).
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| 93 |
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| 94 | =head1 COPYRIGHT
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| 95 |
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| 96 | Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.
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| 97 |
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| 98 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 99 | this file except in compliance with the License. You can obtain a copy
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| 100 | in the file LICENSE in the source distribution or at
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| 101 | L<https://www.openssl.org/source/license.html>.
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| 102 |
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| 103 | =cut
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