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1 | /* $Cambridge: exim/src/src/auths/xtextdecode.c,v 1.1 2004/10/07 13:10:01 ph10 Exp $ */ |
2 | ||
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
7 | /* Copyright (c) University of Cambridge 1995 - 2004 */ | |
8 | /* See the file NOTICE for conditions of use and distribution. */ | |
9 | ||
10 | #include "../exim.h" | |
11 | ||
12 | ||
13 | /************************************************* | |
14 | * Decode byte-string in xtext * | |
15 | *************************************************/ | |
16 | ||
17 | /* This function decodes a string in xtextformat as defined in RFC 1891 and | |
18 | required by the SMTP AUTH extension (RFC 2554). We put the result in a piece of | |
19 | store of equal length - it cannot be longer than this. Although in general the | |
20 | result of decoding an xtext may be binary, in the context in which it is used | |
21 | by Exim (for decoding the value of AUTH on a MAIL command), the result is | |
22 | expected to be an addr-spec. We therefore add on a terminating zero, for | |
23 | convenience. | |
24 | ||
25 | Arguments: | |
26 | code points to the coded string, zero-terminated | |
27 | ptr where to put the pointer to the result, which is in | |
28 | dynamic store | |
29 | ||
30 | Returns: the number of bytes in the result, excluding the final zero; | |
31 | -1 if the input is malformed | |
32 | */ | |
33 | ||
34 | int | |
35 | auth_xtextdecode(uschar *code, uschar **ptr) | |
36 | { | |
37 | register int x; | |
38 | uschar *result = store_get(Ustrlen(code) + 1); | |
39 | *ptr = result; | |
40 | ||
41 | while ((x = (*code++)) != 0) | |
42 | { | |
43 | if (x < 33 || x > 127 || x == '=') return -1; | |
44 | if (x == '+') | |
45 | { | |
46 | register int y; | |
47 | if (!isxdigit((x = (*code++)))) return -1; | |
48 | y = ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10)) << 4; | |
49 | if (!isxdigit((x = (*code++)))) return -1; | |
50 | *result++ = y | ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10)); | |
51 | } | |
52 | else *result++ = x; | |
53 | } | |
54 | ||
55 | *result = 0; | |
56 | return result - *ptr; | |
57 | } | |
58 | ||
59 | /* End of xtextdecode.c */ |