61 lines
2.5 KiB
Markdown
61 lines
2.5 KiB
Markdown
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# base64c
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This is primarily just a fork of a base64 decoder from the FreeBSD codebase. It has received a few modifications:
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* removed all allocations, you are expected to pass in a buffer that has sufficient space and you will get an error (-1) if you run out of space
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* replaced a dynamically generated lookup table with a hardcoded lookup table
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* wrote my own unit tests, i'm sure there are tests for freebsd somewhere but i didn't find them
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# Embedding
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This code is primarily intended to be dropped into an existing code base ( or perhaps using submodules). To do that:
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* grab include/base64c.h
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* grab src/base64c.h
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# Usage
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Call base64c_encoding_length() to calculate how big a buffer you need to encode a string. It's somewhere around 4 times the size of the input string. This length includes a null terminator.
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```c
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char input_string[256];
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size_t new_len = base64c_encoding_length( strlen(input_string));
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unsigned char *buffer = (unsigned char*)malloc(new_len);
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```
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Call base64c_encode() to actually encode your input string as base64. It will write to the buffer and return how many characters were written. If there was an error it will return -1.
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```c
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size_t output_length = base64c_encode(input_string, strlen(input_string), buffer, new_len);
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if (output_length == -1) {
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int x = 1/0; // ERROR!
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}
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```
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Call base64c_decoding_length() to calculate how big a buffer you need to decode. It comes out to about half the size. This number isn't always exact, but it is close to within a byte or two.
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```c
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size_t decode_len = base64c_decoding_length( strlen(buffer) );
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unsigned char *decoded = (unsigned char*)malloc( decode_len );
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```
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Call base64c_decode() to decode an encoded base64 string. It will write to the buffer and return how many characters were written. IF there was an error it will return -1. If the string contains invalid number of characters, or has any characters that are not part of the base64 character set an error will be returned.
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# Building
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You need to bootstrap all the autoconf tools by running ./autogen.sh
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You need to have autoconf installed to do this.
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Once bootstrapped run ./configure
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# Tests
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There are tests in the test/ subfolder. They will be built automatically. There is no special test runner. You can run each of the test cases manually to check whether the code is working properly.
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# References
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(http://web.mit.edu/freebsd/head/contrib/wpa/src/utils/base64.c)
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(https://github.com/freebsd/freebsd/blob/master/contrib/wpa/src/utils/base64.c)
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