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1 | /* |
2 | * ux_x11.c: fetch local auth data for X forwarding. |
3 | */ |
4 | |
5 | #include <ctype.h> |
6 | #include <unistd.h> |
7 | #include "putty.h" |
8 | |
9 | void platform_get_x11_auth(char *display, int *protocol, |
10 | unsigned char *data, int *datalen) |
11 | { |
12 | FILE *fp; |
13 | char *command; |
14 | int maxsize = *datalen; |
15 | char *localbuf; |
16 | |
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17 | /* |
18 | * Normally we should run `xauth list DISPLAYNAME'. However, |
19 | * there's an oddity when the display is local: the display |
20 | * `localhost:0' (or `:0') should become just `:0'. |
21 | */ |
22 | if (!strncmp(display, "localhost:", 10)) |
23 | command = dupprintf("xauth list %s 2>/dev/null", display+9); |
24 | else |
25 | command = dupprintf("xauth list %s 2>/dev/null", display); |
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26 | fp = popen(command, "r"); |
27 | sfree(command); |
28 | |
29 | if (!fp) |
30 | return; /* assume no auth */ |
31 | |
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32 | localbuf = snewn(maxsize, char); |
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33 | |
34 | while (1) { |
35 | /* |
36 | * Read a line from stdin, and attempt to parse it into a |
37 | * display name (ignored), auth protocol, and auth string. |
38 | */ |
39 | int c, i, hexdigit, proto; |
40 | char protoname[64]; |
41 | |
42 | /* Skip the display name. */ |
43 | while (c = getc(fp), c != EOF && c != '\n' && !isspace(c)); |
44 | if (c == EOF) break; |
45 | if (c == '\n') continue; |
46 | |
47 | /* Skip white space. */ |
48 | while (c != EOF && c != '\n' && isspace(c)) |
49 | c = getc(fp); |
50 | if (c == EOF) break; |
51 | if (c == '\n') continue; |
52 | |
53 | /* Read the auth protocol name, and see if it matches any we |
54 | * know about. */ |
55 | i = 0; |
56 | while (c != EOF && c != '\n' && !isspace(c)) { |
57 | if (i < lenof(protoname)-1) protoname[i++] = c; |
58 | c = getc(fp); |
59 | } |
60 | protoname[i] = '\0'; |
61 | |
62 | for (i = X11_NO_AUTH; ++i < X11_NAUTHS ;) { |
63 | if (!strcmp(protoname, x11_authnames[i])) |
64 | break; |
65 | } |
66 | if (i >= X11_NAUTHS || i <= proto) { |
67 | /* Unrecognised protocol name, or a worse one than we already have. |
68 | * Skip this line. */ |
69 | while (c != EOF && c != '\n') |
70 | c = getc(fp); |
71 | if (c == EOF) break; |
72 | } |
73 | proto = i; |
74 | |
75 | /* Skip white space. */ |
76 | while (c != EOF && c != '\n' && isspace(c)) |
77 | c = getc(fp); |
78 | if (c == EOF) break; |
79 | if (c == '\n') continue; |
80 | |
81 | /* |
82 | * Now grab pairs of hex digits and shove them into `data'. |
83 | */ |
84 | i = 0; |
85 | hexdigit = -1; |
86 | while (c != EOF && c != '\n') { |
87 | int hexval = -1; |
88 | if (c >= 'A' && c <= 'F') |
89 | hexval = c + 10 - 'A'; |
90 | if (c >= 'a' && c <= 'f') |
91 | hexval = c + 10 - 'a'; |
92 | if (c >= '0' && c <= '9') |
93 | hexval = c - '0'; |
94 | if (hexval >= 0) { |
95 | if (hexdigit >= 0) { |
96 | hexdigit = (hexdigit << 4) + hexval; |
97 | if (i < maxsize) |
98 | localbuf[i++] = hexdigit; |
99 | hexdigit = -1; |
100 | } else |
101 | hexdigit = hexval; |
102 | } |
103 | c = getc(fp); |
104 | } |
105 | |
106 | *datalen = i; |
107 | *protocol = proto; |
108 | memcpy(data, localbuf, i); |
109 | |
110 | /* Nonetheless, continue looping round; we might find a better one. */ |
111 | } |
112 | pclose(fp); |
113 | sfree(localbuf); |
114 | } |