1 files changed, 104 insertions, 1 deletions

diff --git a/clientloop.c b/clientloop.c
index ae4dce820..ee36cc9e5 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -59,7 +59,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: clientloop.c,v 1.137 2005/06/08 11:25:09 djm Exp $");
+RCSID("$OpenBSD: clientloop.c,v 1.138 2005/06/16 03:38:36 djm Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -208,6 +208,109 @@ get_current_time(void)
         return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
 }
 
+#define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
+void
+client_x11_get_proto(const char *display, const char *xauth_path,
+    u_int trusted, char **_proto, char **_data)
+{
+        char cmd[1024];
+        char line[512];
+        char xdisplay[512];
+        static char proto[512], data[512];
+        FILE *f;
+        int got_data = 0, generated = 0, do_unlink = 0, i;
+        char *xauthdir, *xauthfile;
+        struct stat st;
+
+        xauthdir = xauthfile = NULL;
+        *_proto = proto;
+        *_data = data;
+        proto[0] = data[0] = '\0';
+
+        if (xauth_path == NULL ||(stat(xauth_path, &st) == -1)) {
+                debug("No xauth program.");
+        } else {
+                if (display == NULL) {
+                        debug("x11_get_proto: DISPLAY not set");
+                        return;
+                }
+                /*
+                 * Handle FamilyLocal case where $DISPLAY does
+                 * not match an authorization entry.  For this we
+                 * just try "xauth list unix:displaynum.screennum".
+                 * XXX: "localhost" match to determine FamilyLocal
+                 *      is not perfect.
+                 */
+                if (strncmp(display, "localhost:", 10) == 0) {
+                        snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
+                            display + 10);
+                        display = xdisplay;
+                }
+                if (trusted == 0) {
+                        xauthdir = xmalloc(MAXPATHLEN);
+                        xauthfile = xmalloc(MAXPATHLEN);
+                        strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
+                        if (mkdtemp(xauthdir) != NULL) {
+                                do_unlink = 1;
+                                snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
+                                    xauthdir);
+                                snprintf(cmd, sizeof(cmd),
+                                    "%s -f %s generate %s " SSH_X11_PROTO
+                                    " untrusted timeout 1200 2>" _PATH_DEVNULL,
+                                    xauth_path, xauthfile, display);
+                                debug2("x11_get_proto: %s", cmd);
+                                if (system(cmd) == 0)
+                                        generated = 1;
+                        }
+                }
+                snprintf(cmd, sizeof(cmd),
+                    "%s %s%s list %s . 2>" _PATH_DEVNULL,
+                    xauth_path,
+                    generated ? "-f " : "" ,
+                    generated ? xauthfile : "",
+                    display);
+                debug2("x11_get_proto: %s", cmd);
+                f = popen(cmd, "r");
+                if (f && fgets(line, sizeof(line), f) &&
+                    sscanf(line, "%*s %511s %511s", proto, data) == 2)
+                        got_data = 1;
+                if (f)
+                        pclose(f);
+        }
+
+        if (do_unlink) {
+                unlink(xauthfile);
+                rmdir(xauthdir);
+        }
+        if (xauthdir)
+                xfree(xauthdir);
+        if (xauthfile)
+                xfree(xauthfile);
+
+        /*
+         * If we didn't get authentication data, just make up some
+         * data.  The forwarding code will check the validity of the
+         * response anyway, and substitute this data.  The X11
+         * server, however, will ignore this fake data and use
+         * whatever authentication mechanisms it was using otherwise
+         * for the local connection.
+         */
+        if (!got_data) {
+                u_int32_t rnd = 0;
+
+                logit("Warning: No xauth data; "
+                    "using fake authentication data for X11 forwarding.");
+                strlcpy(proto, SSH_X11_PROTO, sizeof proto);
+                for (i = 0; i < 16; i++) {
+                        if (i % 4 == 0)
+                                rnd = arc4random();
+                        snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
+                            rnd & 0xff);
+                        rnd >>= 8;
+                }
+        }
+}
+
 /*
  * This is called when the interactive is entered.  This checks if there is
  * an EOF coming on stdin.  We must check this explicitly, as select() does