214 lines
5.6 KiB
C
214 lines
5.6 KiB
C
/*
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This is derived from the libb64 project, which has been placed in the public domain.
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For details, see http://sourceforge.net/projects/libb64
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*/
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#include "base64.h"
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int base64_decode_value(char value_in)
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{
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static const char decoding[] = {62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51};
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static const char decoding_size = sizeof(decoding);
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value_in -= 43;
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if (value_in < 0 || value_in >= decoding_size) return -1;
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return decoding[(int)value_in];
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}
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void base64_init_decodestate(base64_decodestate* state_in)
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{
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state_in->step = step_a;
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state_in->plainchar = 0;
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}
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int base64_decode_block(const char* code_in, const int length_in, char* plaintext_out, base64_decodestate* state_in)
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{
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const char* codechar = code_in;
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char* plainchar = plaintext_out;
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char fragment;
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*plainchar = state_in->plainchar;
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switch (state_in->step)
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{
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while (1)
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{
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case step_a:
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do {
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if (codechar == code_in+length_in)
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{
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state_in->step = step_a;
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state_in->plainchar = *plainchar;
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return plainchar - plaintext_out;
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}
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fragment = (char)base64_decode_value(*codechar++);
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} while (fragment < 0);
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*plainchar = (fragment & 0x03f) << 2;
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// fall through
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case step_b:
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do {
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if (codechar == code_in+length_in)
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{
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state_in->step = step_b;
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state_in->plainchar = *plainchar;
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return plainchar - plaintext_out;
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}
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fragment = (char)base64_decode_value(*codechar++);
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} while (fragment < 0);
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*plainchar++ |= (fragment & 0x030) >> 4;
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*plainchar = (fragment & 0x00f) << 4;
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// fall through
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case step_c:
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do {
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if (codechar == code_in+length_in)
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{
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state_in->step = step_c;
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state_in->plainchar = *plainchar;
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return plainchar - plaintext_out;
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}
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fragment = (char)base64_decode_value(*codechar++);
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} while (fragment < 0);
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*plainchar++ |= (fragment & 0x03c) >> 2;
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*plainchar = (fragment & 0x003) << 6;
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// fall through
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case step_d:
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do {
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if (codechar == code_in+length_in)
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{
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state_in->step = step_d;
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state_in->plainchar = *plainchar;
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return plainchar - plaintext_out;
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}
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fragment = (char)base64_decode_value(*codechar++);
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} while (fragment < 0);
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*plainchar++ |= (fragment & 0x03f);
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}
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}
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/* control should not reach here */
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return plainchar - plaintext_out;
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}
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void base64_init_encodestate(base64_encodestate* state_in)
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{
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state_in->step = step_A;
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state_in->result = 0;
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state_in->stepcount = 0;
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}
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char base64_encode_value(char value_in)
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{
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static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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if (value_in > 63) return '=';
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return encoding[(int)value_in];
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}
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int base64_encode_block(const char* plaintext_in, int length_in, char* code_out, base64_encodestate* state_in)
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{
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const char* plainchar = plaintext_in;
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const char* const plaintextend = plaintext_in + length_in;
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char* codechar = code_out;
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char result;
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char fragment;
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result = state_in->result;
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switch (state_in->step)
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{
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while (1)
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{
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case step_A:
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if (plainchar == plaintextend)
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{
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state_in->result = result;
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state_in->step = step_A;
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return codechar - code_out;
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}
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fragment = *plainchar++;
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result = (fragment & 0x0fc) >> 2;
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*codechar++ = base64_encode_value(result);
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result = (fragment & 0x003) << 4;
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// fall through
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case step_B:
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if (plainchar == plaintextend)
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{
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state_in->result = result;
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state_in->step = step_B;
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return codechar - code_out;
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}
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fragment = *plainchar++;
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result |= (fragment & 0x0f0) >> 4;
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*codechar++ = base64_encode_value(result);
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result = (fragment & 0x00f) << 2;
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// fall through
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case step_C:
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if (plainchar == plaintextend)
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{
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state_in->result = result;
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state_in->step = step_C;
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return codechar - code_out;
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}
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fragment = *plainchar++;
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result |= (fragment & 0x0c0) >> 6;
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*codechar++ = base64_encode_value(result);
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result = (fragment & 0x03f) >> 0;
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*codechar++ = base64_encode_value(result);
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++(state_in->stepcount);
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#ifdef BASE64_USE_NEWLINES
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if (state_in->stepcount == BASE64_CHARS_PER_LINE/4)
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{
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*codechar++ = '\n';
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state_in->stepcount = 0;
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}
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#endif
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}
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}
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/* control should not reach here */
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return codechar - code_out;
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}
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int base64_encode_blockend(char* code_out, base64_encodestate* state_in)
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{
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char* codechar = code_out;
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switch (state_in->step)
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{
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case step_B:
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*codechar++ = base64_encode_value(state_in->result);
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*codechar++ = '=';
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*codechar++ = '=';
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break;
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case step_C:
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*codechar++ = base64_encode_value(state_in->result);
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*codechar++ = '=';
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break;
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case step_A:
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break;
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}
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#ifdef BASE64_USE_NEWLINES
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*codechar++ = '\n';
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#endif
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return codechar - code_out;
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}
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// These "one-shot" functions were not in the original project, I have added them and still need to be sure they work
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// note - output MUST be large enough to accomodate the base64'd input (i.e. must be 1/3 bigger than input_len plus the null terminator - 65 bytes for 48-byte input)
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void base64_encode_oneshot(char* input, int input_len, char* output){
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base64_encodestate s;
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char* c = output;
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base64_init_encodestate(&s);
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c += base64_encode_block(input, input_len, output, &s);
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c += base64_encode_blockend(c, &s);
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*c = '\0';
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}
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// note - output MUST be large enough to accomodate the decoded input (i.e. must be at least 3/4 the size of the input - 48 bytes for 64-byte input)
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void base64_decode_oneshot(char* input, int input_len, char* output){
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base64_decodestate s;
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base64_init_decodestate(&s);
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base64_decode_block(input, input_len, output, &s);
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} |