putty/unix/ux_x11.c

116 строки
3.2 KiB
C

/*
* ux_x11.c: fetch local auth data for X forwarding.
*/
#include <ctype.h>
#include <unistd.h>
#include "putty.h"
void platform_get_x11_auth(char *display, int *protocol,
unsigned char *data, int *datalen)
{
FILE *fp;
char *command;
int maxsize = *datalen;
char *localbuf;
int proto = -1;
/*
* Normally we should run `xauth list DISPLAYNAME'. However,
* there's an oddity when the display is local: the display
* `localhost:0' (or `:0') should become just `:0'.
*/
if (!strncmp(display, "localhost:", 10))
command = dupprintf("xauth list %s 2>/dev/null", display+9);
else
command = dupprintf("xauth list %s 2>/dev/null", display);
fp = popen(command, "r");
sfree(command);
if (!fp)
return; /* assume no auth */
localbuf = snewn(maxsize, char);
while (1) {
/*
* Read a line from stdin, and attempt to parse it into a
* display name (ignored), auth protocol, and auth string.
*/
int c, i, hexdigit;
char protoname[64];
/* Skip the display name. */
while (c = getc(fp), c != EOF && c != '\n' && !isspace(c));
if (c == EOF) break;
if (c == '\n') continue;
/* Skip white space. */
while (c != EOF && c != '\n' && isspace(c))
c = getc(fp);
if (c == EOF) break;
if (c == '\n') continue;
/* Read the auth protocol name, and see if it matches any we
* know about. */
i = 0;
while (c != EOF && c != '\n' && !isspace(c)) {
if (i < lenof(protoname)-1) protoname[i++] = c;
c = getc(fp);
}
protoname[i] = '\0';
for (i = X11_NO_AUTH; ++i < X11_NAUTHS ;) {
if (!strcmp(protoname, x11_authnames[i]))
break;
}
if (i >= X11_NAUTHS || i <= proto) {
/* Unrecognised protocol name, or a worse one than we already have.
* Skip this line. */
while (c != EOF && c != '\n')
c = getc(fp);
if (c == EOF) break;
}
proto = i;
/* Skip white space. */
while (c != EOF && c != '\n' && isspace(c))
c = getc(fp);
if (c == EOF) break;
if (c == '\n') continue;
/*
* Now grab pairs of hex digits and shove them into `data'.
*/
i = 0;
hexdigit = -1;
while (c != EOF && c != '\n') {
int hexval = -1;
if (c >= 'A' && c <= 'F')
hexval = c + 10 - 'A';
if (c >= 'a' && c <= 'f')
hexval = c + 10 - 'a';
if (c >= '0' && c <= '9')
hexval = c - '0';
if (hexval >= 0) {
if (hexdigit >= 0) {
hexdigit = (hexdigit << 4) + hexval;
if (i < maxsize)
localbuf[i++] = hexdigit;
hexdigit = -1;
} else
hexdigit = hexval;
}
c = getc(fp);
}
*datalen = i;
*protocol = proto;
memcpy(data, localbuf, i);
/* Nonetheless, continue looping round; we might find a better one. */
}
pclose(fp);
sfree(localbuf);
}