projects / exim.git / blame
| Commit | Line | Data |
|---|---|---|
| 0756eb3c PH |
1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * | |
| 3 | *************************************************/ | |
| 4 | ||
| 0a49a7a4 | 5 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
| 0756eb3c PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | ||
| 8 | #include "../exim.h" | |
| 9 | ||
| 10 | ||
| 11 | /************************************************* | |
| 12 | * Decode byte-string in base 64 * | |
| 13 | *************************************************/ | |
| 14 | ||
| 15 | /* This function decodes a string in base 64 format as defined in RFC 2045 | |
| 16 | (MIME) and required by the SMTP AUTH extension (RFC 2554). The decoding | |
| 17 | algorithm is written out in a straightforward way. Turning it into some kind of | |
| 18 | compact loop is messy and would probably run more slowly. | |
| 19 | ||
| 20 | Arguments: | |
| 21 | code points to the coded string, zero-terminated | |
| 22 | ptr where to put the pointer to the result, which is in | |
| f78eb7c6 | 23 | dynamic store, and zero-terminated |
| 0756eb3c PH |
24 | |
| 25 | Returns: the number of bytes in the result, | |
| 26 | or -1 if the input was malformed | |
| 27 | ||
| 28 | A zero is added on to the end to make it easy in cases where the result is to | |
| 29 | be interpreted as text. This is not included in the count. */ | |
| 30 | ||
| 31 | static uschar dec64table[] = { | |
| 32 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, /* 0-15 */ | |
| 33 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, /* 16-31 */ | |
| 34 | 255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63, /* 32-47 */ | |
| 35 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255,255,255,255, /* 48-63 */ | |
| 36 | 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 64-79 */ | |
| 37 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255,255, /* 80-95 */ | |
| 38 | 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 96-111 */ | |
| 39 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255 /* 112-127*/ | |
| 40 | }; | |
| 41 | ||
| 42 | int | |
| 43 | auth_b64decode(uschar *code, uschar **ptr) | |
| 44 | { | |
| 45 | register int x, y; | |
| 46 | uschar *result = store_get(3*(Ustrlen(code)/4) + 1); | |
| 47 | ||
| 48 | *ptr = result; | |
| 49 | ||
| 50 | /* Each cycle of the loop handles a quantum of 4 input bytes. For the last | |
| 51 | quantum this may decode to 1, 2, or 3 output bytes. */ | |
| 52 | ||
| 53 | while ((x = (*code++)) != 0) | |
| 54 | { | |
| 55 | if (x > 127 || (x = dec64table[x]) == 255) return -1; | |
| 56 | if ((y = (*code++)) == 0 || (y = dec64table[y]) == 255) | |
| 57 | return -1; | |
| 58 | *result++ = (x << 2) | (y >> 4); | |
| 59 | ||
| 60 | if ((x = (*code++)) == '=') | |
| 61 | { | |
| 62 | if (*code++ != '=' || *code != 0) return -1; | |
| 63 | } | |
| 64 | else | |
| 65 | { | |
| 66 | if (x > 127 || (x = dec64table[x]) == 255) return -1; | |
| 67 | *result++ = (y << 4) | (x >> 2); | |
| 68 | if ((y = (*code++)) == '=') | |
| 69 | { | |
| 70 | if (*code != 0) return -1; | |
| 71 | } | |
| 72 | else | |
| 73 | { | |
| 74 | if (y > 127 || (y = dec64table[y]) == 255) return -1; | |
| 75 | *result++ = (x << 6) | y; | |
| 76 | } | |
| 77 | } | |
| 78 | } | |
| 79 | ||
| 80 | *result = 0; | |
| 81 | return result - *ptr; | |
| 82 | } | |
| 83 | ||
| 84 | /* End of b64decode.c */ |