103 lines
3.0 KiB
C
103 lines
3.0 KiB
C
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/*
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cencoder.c - c source to a base64 encoding algorithm implementation
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This is part of the libb64 project, and 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 "cencode.h"
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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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}
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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) {
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return '=';
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}
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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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while (1) {
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case step_A:
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if (plainchar == plaintextend) {
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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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case step_B:
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if (plainchar == plaintextend) {
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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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case step_C:
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if (plainchar == plaintextend) {
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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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}
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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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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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*codechar = 0x00;
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return codechar - code_out;
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}
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int base64_encode_chars(const char* plaintext_in, int length_in, char* code_out)
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{
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base64_encodestate _state;
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base64_init_encodestate(&_state);
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int len = base64_encode_block(plaintext_in, length_in, code_out, &_state);
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return len + base64_encode_blockend((code_out + len), &_state);
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}
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