| 1 | /* |
| 2 | * ux_x11.c: fetch local auth data for X forwarding. |
| 3 | */ |
| 4 | |
| 5 | #include <ctype.h> |
| 6 | #include <unistd.h> |
| 7 | #include <assert.h> |
| 8 | #include "putty.h" |
| 9 | #include "ssh.h" |
| 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; |
| 18 | int proto = -1; |
| 19 | |
| 20 | display = x11_display(display); |
| 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 | */ |
| 26 | if (!strncmp(display, "localhost:", 10) |
| 27 | || !strncmp(display, "unix:", 5)) |
| 28 | command = dupprintf("xauth list %s 2>/dev/null", |
| 29 | strchr(display, ':')); |
| 30 | else |
| 31 | command = dupprintf("xauth list %s 2>/dev/null", display); |
| 32 | sfree(display); |
| 33 | fp = popen(command, "r"); |
| 34 | sfree(command); |
| 35 | |
| 36 | if (!fp) |
| 37 | return; /* assume no auth */ |
| 38 | |
| 39 | localbuf = snewn(maxsize, char); |
| 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 | */ |
| 46 | int c, i, hexdigit; |
| 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 | } |