diff options
Diffstat (limited to 'lib/base64.c')
| -rw-r--r-- | lib/base64.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/lib/base64.c b/lib/base64.c new file mode 100644 index 0000000..1507b02 --- /dev/null +++ b/lib/base64.c @@ -0,0 +1,198 @@ +// SPDX-License-Identifier: NONE +/* + * This is part of the libb64 project, and has been placed in the public domain. + * For details, see http://sourceforge.net/projects/libb64 + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "base64.h" + +static const int CHARS_PER_LINE = 72; +static const char *ENCODING = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +void base64_init_encodestate(struct base64_encodestate *state_in) +{ + state_in->step = step_A; + state_in->result = 0; + state_in->stepcount = 0; +} + +char base64_encode_value(char value_in) +{ + if (value_in > 63) + return '='; + return ENCODING[(int)value_in]; +} + +int base64_encode_block(const char *plaintext_in, int length_in, char *code_out, + struct base64_encodestate *state_in) +{ + const char *plainchar = plaintext_in; + const char *const plaintextend = plaintext_in + length_in; + char *codechar = code_out; + char result; + char fragment; + + result = state_in->result; + + switch (state_in->step) { + while (1) { + case step_A: + if (plainchar == plaintextend) { + state_in->result = result; + state_in->step = step_A; + return codechar - code_out; + } + fragment = *plainchar++; + result = (fragment & 0x0fc) >> 2; + *codechar++ = base64_encode_value(result); + result = (fragment & 0x003) << 4; + /* fall through */ + case step_B: + if (plainchar == plaintextend) { + state_in->result = result; + state_in->step = step_B; + return codechar - code_out; + } + fragment = *plainchar++; + result |= (fragment & 0x0f0) >> 4; + *codechar++ = base64_encode_value(result); + result = (fragment & 0x00f) << 2; + /* fall through */ + case step_C: + if (plainchar == plaintextend) { + state_in->result = result; + state_in->step = step_C; + return codechar - code_out; + } + fragment = *plainchar++; + result |= (fragment & 0x0c0) >> 6; + *codechar++ = base64_encode_value(result); + result = (fragment & 0x03f) >> 0; + *codechar++ = base64_encode_value(result); + + ++(state_in->stepcount); + if (state_in->stepcount == CHARS_PER_LINE/4) { + *codechar++ = '\n'; + state_in->stepcount = 0; + } + } + } + /* control should not reach here */ + return codechar - code_out; +} + +int base64_encode_blockend(char *code_out, struct base64_encodestate *state_in) +{ + char *codechar = code_out; + + switch (state_in->step) { + case step_B: + *codechar++ = base64_encode_value(state_in->result); + *codechar++ = '='; + *codechar++ = '='; + break; + case step_C: + *codechar++ = base64_encode_value(state_in->result); + *codechar++ = '='; + break; + case step_A: + break; + } + *codechar++ = '\n'; + + return codechar - code_out; +} + + +signed char base64_decode_value(signed char value_in) +{ + static const signed 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 + }; + value_in -= 43; + if (value_in < 0 || value_in >= 80) + return -1; + return decoding[(int)value_in]; +} + +void base64_init_decodestate(struct base64_decodestate *state_in) +{ + state_in->step = step_a; + state_in->plainchar = 0; +} + +int base64_decode_block(const char *code_in, int length_in, char *plaintext_out, + struct base64_decodestate *state_in) +{ + const char *codec = code_in; + char *plainc = plaintext_out; + signed char fragmt; + + *plainc = state_in->plainchar; + + switch (state_in->step) { + while (1) { + case step_a: + do { + if (codec == code_in+length_in) { + state_in->step = step_a; + state_in->plainchar = *plainc; + return plainc - plaintext_out; + } + fragmt = base64_decode_value(*codec++); + } while (fragmt < 0); + *plainc = (fragmt & 0x03f) << 2; + /* fall through */ + case step_b: + do { + if (codec == code_in+length_in) { + state_in->step = step_b; + state_in->plainchar = *plainc; + return plainc - plaintext_out; + } + fragmt = base64_decode_value(*codec++); + } while (fragmt < 0); + *plainc++ |= (fragmt & 0x030) >> 4; + *plainc = (fragmt & 0x00f) << 4; + /* fall through */ + case step_c: + do { + if (codec == code_in+length_in) { + state_in->step = step_c; + state_in->plainchar = *plainc; + return plainc - plaintext_out; + } + fragmt = base64_decode_value(*codec++); + } while (fragmt < 0); + *plainc++ |= (fragmt & 0x03c) >> 2; + *plainc = (fragmt & 0x003) << 6; + /* fall through */ + case step_d: + do { + if (codec == code_in+length_in) { + state_in->step = step_d; + state_in->plainchar = *plainc; + return plainc - plaintext_out; + } + fragmt = base64_decode_value(*codec++); + } while (fragmt < 0); + *plainc++ |= (fragmt & 0x03f); + } + } + /* control should not reach here */ + return plainc - plaintext_out; +} |