/*********************************************************************\ MODULE NAME: b64.c AUTHOR: Bob Trower 08/04/01 PROJECT: Crypt Data Packaging COPYRIGHT: Copyright (c) Trantor Standard Systems Inc., 2001 NOTE: This source code may be used as you wish, subject to the MIT license. See the LICENCE section below. DESCRIPTION: This little utility implements the Base64 Content-Transfer-Encoding standard described in RFC1113 (http://www.faqs.org/rfcs/rfc1113.html). This is the coding scheme used by MIME to allow binary data to be transferred by SMTP mail. Groups of 3 bytes from a binary stream are coded as groups of 4 bytes in a text stream. The input stream is 'padded' with zeros to create an input that is an even multiple of 3. A special character ('=') is used to denote padding so that the stream can be decoded back to its exact size. Encoded output is formatted in lines which should be a maximum of 72 characters to conform to the specification. This program defaults to 72 characters, but will allow more or less through the use of a switch. The program enforces a minimum line size of 4 characters. Example encoding: The stream 'ABCD' is 32 bits long. It is mapped as follows: ABCD A (65) B (66) C (67) D (68) (None) (None) 01000001 01000010 01000011 01000100 16 (Q) 20 (U) 9 (J) 3 (D) 17 (R) 0 (A) NA (=) NA (=) 010000 010100 001001 000011 010001 000000 000000 000000 QUJDRA== Decoding is the process in reverse. A 'decode' lookup table has been created to avoid string scans. DESIGN GOALS: Specifically: Code is a stand-alone utility to perform base64 encoding/decoding. It should be genuinely useful when the need arises and it meets a need that is likely to occur for some users. Code acts as sample code to show the author's design and coding style. Generally: This program is designed to survive: Everything you need is in a single source file. It compiles cleanly using a vanilla ANSI C compiler. It does its job correctly with a minimum of fuss. The code is not overly clever, not overly simplistic and not overly verbose. Access is 'cut and paste' from a web page. Terms of use are reasonable. VALIDATION: Non-trivial code is never without errors. This file likely has some problems, since it has only been tested by the author. It is expected with most source code that there is a period of 'burn-in' when problems are identified and corrected. That being said, it is possible to have 'reasonably correct' code by following a regime of unit test that covers the most likely cases and regression testing prior to release. This has been done with this code and it has a good probability of performing as expected. Unit Test Cases: case 0:empty file: CASE0.DAT -> -> (Zero length target file created on both encode and decode.) case 1:One input character: CASE1.DAT A -> QQ== -> A case 2:Two input characters: CASE2.DAT AB -> QUJD -> AB case 3:Three input characters: CASE3.DAT ABC -> QUJD -> ABC case 4:Four input characters: case4.dat ABCD -> QUJDRA== -> ABCD case 5:All chars from 0 to ff, linesize set to 50: AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIj JCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZH SElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWpr bG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6P kJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKz tLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX 2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7 /P3+/w== case 6:Mime Block from e-mail: (Data same as test case 5) case 7: Large files: Tested 28 MB file in/out. case 8: Random Binary Integrity: This binary program (b64.exe) was encoded to base64, back to binary and then executed. case 9 Stress: All files in a working directory encoded/decoded and compared with file comparison utility to ensure that multiple runs do not cause problems such as exhausting file handles, tmp storage, etc. ------------- Syntax, operation and failure: All options/switches tested. Performs as expected. case 10: No Args -- Shows Usage Screen Return Code 1 (Invalid Syntax) case 11: One Arg (invalid) -- Shows Usage Screen Return Code 1 (Invalid Syntax) case 12: One Arg Help (-?) -- Shows detailed Usage Screen. Return Code 0 (Success -- help request is valid). case 13: One Arg Help (-h) -- Shows detailed Usage Screen. Return Code 0 (Success -- help request is valid). case 14: One Arg (valid) -- Uses stdin/stdout (filter) Return Code 0 (Sucess) case 15: Two Args (invalid file) -- shows system error. Return Code 2 (File Error) case 16: Encode non-existent file -- shows system error. Return Code 2 (File Error) case 17: Out of disk space -- shows system error. Return Code 3 (File I/O Error) ------------- Compile/Regression test: gcc compiled binary under Cygwin Microsoft Visual Studio under Windows 2000 Microsoft Version 6.0 C under Windows 2000 DEPENDENCIES: None LICENCE: Copyright (c) 2001 Bob Trower, Trantor Standard Systems Inc. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. VERSION HISTORY: Bob Trower 08/04/01 -- Create Version 0.00.00B \******************************************************************* */ #include #include #include #include "b64.h" /* ** Translation Table as described in RFC1113 */ static const char cb64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; /* ** Translation Table to decode (created by author) */ static const char cd64[] = "|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`abcdefghijklmnopq"; /* ** encodeblock ** ** encode 3 8-bit binary bytes as 4 '6-bit' characters */ static void encodeblock(uint8_t *wordin, uint8_t *wordout, int wordlen) { wordout[0] = cb64[(unsigned)wordin[0] >> 2]; wordout[1] = cb64[((unsigned)(wordin[0] & 0x03) << 4) | ((unsigned)(wordin[1] & 0xf0) >> 4)]; wordout[2] = (uint8_t)(wordlen > 1) ? cb64[((unsigned)(wordin[1] & 0x0f) << 2) | ((unsigned)(wordin[2] & 0xc0) >> 6)] : '='; wordout[3] = (uint8_t)(wordlen > 2) ? cb64[wordin[2] & 0x3f] : '='; } /* ** encode ** ** base64 encode a stream adding padding and line breaks as per spec. */ int b64encode(const char *in, const size_t insize, void *vp, size_t outsize, int linesize) { const char *inp; unsigned i; uint8_t wordout[4]; uint8_t wordin[3]; char *out = vp; char *outp; int blocksout; int wordlen; wordlen = 0; for (blocksout = 0, inp = in, outp = out; (size_t)(inp - in) < insize && (size_t)(outp - out) < outsize;) { for (wordlen = 0, i = 0; i < sizeof(wordin); i++) { wordin[i] = (uint8_t) *inp++; if ((size_t)(inp - in) <= insize) { wordlen++; } else { wordin[i] = 0x0; } } if (wordlen > 0) { encodeblock(wordin, wordout, wordlen); for (i = 0; i < sizeof(wordout) ; i++) { *outp++ = wordout[i]; } blocksout++; } if (linesize > 0) { if (blocksout >= (int)(linesize / sizeof(wordout)) || (size_t)(inp - in) >= insize) { if (blocksout) { *outp++ = '\r'; *outp++ = '\n'; } blocksout = 0; } } } return (int)(outp - out); } /* ** decodeblock ** ** decode 4 '6-bit' characters into 3 8-bit binary bytes */ static void decodeblock(uint8_t wordin[4], uint8_t wordout[3]) { wordout[0] = (uint8_t) ((unsigned)wordin[0] << 2 | (unsigned)wordin[1] >> 4); wordout[1] = (uint8_t) ((unsigned)wordin[1] << 4 | (unsigned)wordin[2] >> 2); wordout[2] = (uint8_t) (((wordin[2] << 6) & 0xc0) | wordin[3]); } /* ** decode ** ** decode a base64 encoded stream discarding padding, line breaks and noise */ int b64decode(const char *in, const size_t insize, void *vp, size_t outsize) { const char *inp; unsigned wordlen; unsigned i; uint8_t wordout[3]; uint8_t wordin[4]; uint8_t v; char *out = vp; char *outp; for (inp = in, outp = out ; (size_t)(inp - in) < insize && (size_t)(outp - out) < outsize ; ) { for (wordlen = 0, i = 0 ; i < sizeof(wordin) && (size_t)(inp - in) < insize ; i++) { /* get a single character */ for (v = 0; (size_t)(inp - in) <= insize && v == 0 ; ) { if (*inp == '\r' && *(inp + 1) == '\n') { inp += 2; } else { v = (uint8_t) *inp++; v = (uint8_t) ((v < 43 || v > 122) ? 0 : cd64[v - 43]); if (v) { v = (uint8_t) ((v == '$') ? 0 : v - 61); } } } /* perhaps 0x0 pad */ if ((size_t)(inp - in) <= insize) { wordlen += 1; if (v) { wordin[i] = (uint8_t) (v - 1); } } else { wordin[i] = 0x0; } } if (wordlen > 0) { decodeblock(wordin, wordout); for (i = 0; i < wordlen - 1 ; i++) { *outp++ = wordout[i]; } } } return (int)(outp - out); } /* return the encoded size for n bytes input */ int b64_encsize(unsigned n) { return ((4 * n) / 3) + 4; }