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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 xtext * | |
13 | *************************************************/ | |
14 | ||
15 | /* This function decodes a string in xtextformat as defined in RFC 1891 and | |
16 | required by the SMTP AUTH extension (RFC 2554). We put the result in a piece of | |
17 | store of equal length - it cannot be longer than this. Although in general the | |
18 | result of decoding an xtext may be binary, in the context in which it is used | |
19 | by Exim (for decoding the value of AUTH on a MAIL command), the result is | |
20 | expected to be an addr-spec. We therefore add on a terminating zero, for | |
21 | convenience. | |
22 | ||
23 | Arguments: | |
24 | code points to the coded string, zero-terminated | |
25 | ptr where to put the pointer to the result, which is in | |
26 | dynamic store | |
27 | ||
28 | Returns: the number of bytes in the result, excluding the final zero; | |
29 | -1 if the input is malformed | |
30 | */ | |
31 | ||
32 | int | |
33 | auth_xtextdecode(uschar *code, uschar **ptr) | |
34 | { | |
35 | register int x; | |
36 | uschar *result = store_get(Ustrlen(code) + 1); | |
37 | *ptr = result; | |
38 | ||
39 | while ((x = (*code++)) != 0) | |
40 | { | |
41 | if (x < 33 || x > 127 || x == '=') return -1; | |
42 | if (x == '+') | |
43 | { | |
44 | register int y; | |
45 | if (!isxdigit((x = (*code++)))) return -1; | |
46 | y = ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10)) << 4; | |
47 | if (!isxdigit((x = (*code++)))) return -1; | |
48 | *result++ = y | ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10)); | |
49 | } | |
50 | else *result++ = x; | |
51 | } | |
52 | ||
53 | *result = 0; | |
54 | return result - *ptr; | |
55 | } | |
56 | ||
57 | /* End of xtextdecode.c */ |