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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; |
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16 | int proto = -1; |
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17 | |
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18 | /* |
19 | * Normally we should run `xauth list DISPLAYNAME'. However, |
20 | * there's an oddity when the display is local: the display |
21 | * `localhost:0' (or `:0') should become just `:0'. |
22 | */ |
23 | if (!strncmp(display, "localhost:", 10)) |
24 | command = dupprintf("xauth list %s 2>/dev/null", display+9); |
25 | else |
26 | command = dupprintf("xauth list %s 2>/dev/null", display); |
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27 | fp = popen(command, "r"); |
28 | sfree(command); |
29 | |
30 | if (!fp) |
31 | return; /* assume no auth */ |
32 | |
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33 | localbuf = snewn(maxsize, char); |
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34 | |
35 | while (1) { |
36 | /* |
37 | * Read a line from stdin, and attempt to parse it into a |
38 | * display name (ignored), auth protocol, and auth string. |
39 | */ |
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40 | int c, i, hexdigit; |
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41 | char protoname[64]; |
42 | |
43 | /* Skip the display name. */ |
44 | while (c = getc(fp), c != EOF && c != '\n' && !isspace(c)); |
45 | if (c == EOF) break; |
46 | if (c == '\n') continue; |
47 | |
48 | /* Skip white space. */ |
49 | while (c != EOF && c != '\n' && isspace(c)) |
50 | c = getc(fp); |
51 | if (c == EOF) break; |
52 | if (c == '\n') continue; |
53 | |
54 | /* Read the auth protocol name, and see if it matches any we |
55 | * know about. */ |
56 | i = 0; |
57 | while (c != EOF && c != '\n' && !isspace(c)) { |
58 | if (i < lenof(protoname)-1) protoname[i++] = c; |
59 | c = getc(fp); |
60 | } |
61 | protoname[i] = '\0'; |
62 | |
63 | for (i = X11_NO_AUTH; ++i < X11_NAUTHS ;) { |
64 | if (!strcmp(protoname, x11_authnames[i])) |
65 | break; |
66 | } |
67 | if (i >= X11_NAUTHS || i <= proto) { |
68 | /* Unrecognised protocol name, or a worse one than we already have. |
69 | * Skip this line. */ |
70 | while (c != EOF && c != '\n') |
71 | c = getc(fp); |
72 | if (c == EOF) break; |
73 | } |
74 | proto = i; |
75 | |
76 | /* Skip white space. */ |
77 | while (c != EOF && c != '\n' && isspace(c)) |
78 | c = getc(fp); |
79 | if (c == EOF) break; |
80 | if (c == '\n') continue; |
81 | |
82 | /* |
83 | * Now grab pairs of hex digits and shove them into `data'. |
84 | */ |
85 | i = 0; |
86 | hexdigit = -1; |
87 | while (c != EOF && c != '\n') { |
88 | int hexval = -1; |
89 | if (c >= 'A' && c <= 'F') |
90 | hexval = c + 10 - 'A'; |
91 | if (c >= 'a' && c <= 'f') |
92 | hexval = c + 10 - 'a'; |
93 | if (c >= '0' && c <= '9') |
94 | hexval = c - '0'; |
95 | if (hexval >= 0) { |
96 | if (hexdigit >= 0) { |
97 | hexdigit = (hexdigit << 4) + hexval; |
98 | if (i < maxsize) |
99 | localbuf[i++] = hexdigit; |
100 | hexdigit = -1; |
101 | } else |
102 | hexdigit = hexval; |
103 | } |
104 | c = getc(fp); |
105 | } |
106 | |
107 | *datalen = i; |
108 | *protocol = proto; |
109 | memcpy(data, localbuf, i); |
110 | |
111 | /* Nonetheless, continue looping round; we might find a better one. */ |
112 | } |
113 | pclose(fp); |
114 | sfree(localbuf); |
115 | } |