| Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame^] | 1 | /* |
| 2 | cencoder.c - c source to a base64 encoding algorithm implementation |
| 3 | |
| 4 | This is part of the libb64 project, and has been placed in the public domain. |
| 5 | For details, see http://sourceforge.net/projects/libb64 |
| 6 | */ |
| 7 | |
| 8 | #include <libzrtpcpp/zrtpB64Encode.h> |
| 9 | |
| 10 | const int CHARS_PER_LINE = 72; |
| 11 | |
| 12 | void base64_init_encodestate(base64_encodestate* state_in, int lineLength) |
| 13 | { |
| 14 | state_in->step = step_A; |
| 15 | state_in->result = 0; |
| 16 | state_in->stepcount = 0; |
| 17 | if (lineLength < 0) |
| 18 | state_in->lineLength = CHARS_PER_LINE / 4; |
| 19 | else |
| 20 | state_in->lineLength = (lineLength+3) / 4; |
| 21 | } |
| 22 | |
| 23 | char base64_encode_value(const int8_t value_in) |
| 24 | { |
| 25 | static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 26 | if (value_in > 63) return '='; |
| 27 | return encoding[(int)value_in]; |
| 28 | } |
| 29 | |
| 30 | int base64_encode_block(const uint8_t *plaintext_in, int length_in, char* code_out, base64_encodestate* state_in) |
| 31 | { |
| 32 | const uint8_t *plainchar = plaintext_in; |
| 33 | const uint8_t *const plaintextend = plaintext_in + length_in; |
| 34 | char* codechar = code_out; |
| 35 | char result; |
| 36 | char fragment; |
| 37 | |
| 38 | result = state_in->result; |
| 39 | |
| 40 | switch (state_in->step) |
| 41 | { |
| 42 | while (1) |
| 43 | { |
| 44 | case step_A: |
| 45 | if (plainchar == plaintextend) |
| 46 | { |
| 47 | state_in->result = result; |
| 48 | state_in->step = step_A; |
| 49 | return codechar - code_out; |
| 50 | } |
| 51 | fragment = *plainchar++; |
| 52 | result = (fragment & 0x0fc) >> 2; |
| 53 | *codechar++ = base64_encode_value(result); |
| 54 | result = (fragment & 0x003) << 4; |
| 55 | case step_B: |
| 56 | if (plainchar == plaintextend) |
| 57 | { |
| 58 | state_in->result = result; |
| 59 | state_in->step = step_B; |
| 60 | return codechar - code_out; |
| 61 | } |
| 62 | fragment = *plainchar++; |
| 63 | result |= (fragment & 0x0f0) >> 4; |
| 64 | *codechar++ = base64_encode_value(result); |
| 65 | result = (fragment & 0x00f) << 2; |
| 66 | case step_C: |
| 67 | if (plainchar == plaintextend) |
| 68 | { |
| 69 | state_in->result = result; |
| 70 | state_in->step = step_C; |
| 71 | return codechar - code_out; |
| 72 | } |
| 73 | fragment = *plainchar++; |
| 74 | result |= (fragment & 0x0c0) >> 6; |
| 75 | *codechar++ = base64_encode_value(result); |
| 76 | result = (fragment & 0x03f) >> 0; |
| 77 | *codechar++ = base64_encode_value(result); |
| 78 | |
| 79 | if (state_in->lineLength > 0) { |
| 80 | state_in->stepcount++; |
| 81 | if (state_in->stepcount == state_in->lineLength) |
| 82 | { |
| 83 | *codechar++ = '\n'; |
| 84 | state_in->stepcount = 0; |
| 85 | } |
| 86 | } |
| 87 | } |
| 88 | } |
| 89 | /* control should not reach here */ |
| 90 | return codechar - code_out; |
| 91 | } |
| 92 | |
| 93 | int base64_encode_blockend(char* code_out, base64_encodestate* state_in) |
| 94 | { |
| 95 | char* codechar = code_out; |
| 96 | |
| 97 | switch (state_in->step) |
| 98 | { |
| 99 | case step_B: |
| 100 | *codechar++ = base64_encode_value(state_in->result); |
| 101 | *codechar++ = '='; |
| 102 | *codechar++ = '='; |
| 103 | break; |
| 104 | case step_C: |
| 105 | *codechar++ = base64_encode_value(state_in->result); |
| 106 | *codechar++ = '='; |
| 107 | break; |
| 108 | case step_A: |
| 109 | break; |
| 110 | } |
| 111 | if (state_in->lineLength > 0) |
| 112 | *codechar++ = '\n'; |
| 113 | |
| 114 | return codechar - code_out; |
| 115 | } |
| 116 | |