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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> |
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7 | #include <assert.h> |
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8 | #include "putty.h" |
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9 | #include "ssh.h" |
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10 | |
11 | void platform_get_x11_auth(char *display, int *protocol, |
12 | unsigned char *data, int *datalen) |
13 | { |
14 | FILE *fp; |
15 | char *command; |
16 | int maxsize = *datalen; |
17 | char *localbuf; |
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18 | int proto = -1; |
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19 | |
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20 | display = x11_display(display); |
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21 | /* |
22 | * Normally we should run `xauth list DISPLAYNAME'. However, |
23 | * there's an oddity when the display is local: the display |
24 | * `localhost:0' (or `:0') should become just `:0'. |
25 | */ |
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26 | if (!strncmp(display, "localhost:", 10) |
27 | || !strncmp(display, "unix:", 5)) |
28 | command = dupprintf("xauth list %s 2>/dev/null", |
29 | strchr(display, ':')); |
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30 | else |
31 | command = dupprintf("xauth list %s 2>/dev/null", display); |
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32 | sfree(display); |
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33 | fp = popen(command, "r"); |
34 | sfree(command); |
35 | |
36 | if (!fp) |
37 | return; /* assume no auth */ |
38 | |
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39 | localbuf = snewn(maxsize, char); |
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40 | |
41 | while (1) { |
42 | /* |
43 | * Read a line from stdin, and attempt to parse it into a |
44 | * display name (ignored), auth protocol, and auth string. |
45 | */ |
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46 | int c, i, hexdigit; |
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47 | char protoname[64]; |
48 | |
49 | /* Skip the display name. */ |
50 | while (c = getc(fp), c != EOF && c != '\n' && !isspace(c)); |
51 | if (c == EOF) break; |
52 | if (c == '\n') continue; |
53 | |
54 | /* Skip white space. */ |
55 | while (c != EOF && c != '\n' && isspace(c)) |
56 | c = getc(fp); |
57 | if (c == EOF) break; |
58 | if (c == '\n') continue; |
59 | |
60 | /* Read the auth protocol name, and see if it matches any we |
61 | * know about. */ |
62 | i = 0; |
63 | while (c != EOF && c != '\n' && !isspace(c)) { |
64 | if (i < lenof(protoname)-1) protoname[i++] = c; |
65 | c = getc(fp); |
66 | } |
67 | protoname[i] = '\0'; |
68 | |
69 | for (i = X11_NO_AUTH; ++i < X11_NAUTHS ;) { |
70 | if (!strcmp(protoname, x11_authnames[i])) |
71 | break; |
72 | } |
73 | if (i >= X11_NAUTHS || i <= proto) { |
74 | /* Unrecognised protocol name, or a worse one than we already have. |
75 | * Skip this line. */ |
76 | while (c != EOF && c != '\n') |
77 | c = getc(fp); |
78 | if (c == EOF) break; |
79 | } |
80 | proto = i; |
81 | |
82 | /* Skip white space. */ |
83 | while (c != EOF && c != '\n' && isspace(c)) |
84 | c = getc(fp); |
85 | if (c == EOF) break; |
86 | if (c == '\n') continue; |
87 | |
88 | /* |
89 | * Now grab pairs of hex digits and shove them into `data'. |
90 | */ |
91 | i = 0; |
92 | hexdigit = -1; |
93 | while (c != EOF && c != '\n') { |
94 | int hexval = -1; |
95 | if (c >= 'A' && c <= 'F') |
96 | hexval = c + 10 - 'A'; |
97 | if (c >= 'a' && c <= 'f') |
98 | hexval = c + 10 - 'a'; |
99 | if (c >= '0' && c <= '9') |
100 | hexval = c - '0'; |
101 | if (hexval >= 0) { |
102 | if (hexdigit >= 0) { |
103 | hexdigit = (hexdigit << 4) + hexval; |
104 | if (i < maxsize) |
105 | localbuf[i++] = hexdigit; |
106 | hexdigit = -1; |
107 | } else |
108 | hexdigit = hexval; |
109 | } |
110 | c = getc(fp); |
111 | } |
112 | |
113 | *datalen = i; |
114 | *protocol = proto; |
115 | memcpy(data, localbuf, i); |
116 | |
117 | /* Nonetheless, continue looping round; we might find a better one. */ |
118 | } |
119 | pclose(fp); |
120 | sfree(localbuf); |
121 | } |