Change security policy -- only accept requests from current host.

diff --git a/Demo/pysvr/pysvr.py b/Demo/pysvr/pysvr.py
index 4488386dd93992f2518f0f966eafd562b0b9f324..329909b686bca53682a0c8c1756fed65d48d38e5 100755 (executable)
--- a/Demo/pysvr/pysvr.py
+++ b/Demo/pysvr/pysvr.py
@@ -6,13 +6,15 @@ This is really a prototype for the same thing in C.
 
 Usage: pysvr.py [port]
 
+For security reasons, it only accepts requests from the current host.
+This can still be insecure, but restricts violations from people who
+can log in on your machine.  Use with caution!
+
 """
 
 import sys, os, string, getopt, thread, socket, traceback
 
-OK_DOMAINS = [".cnri.reston.va.us", ".python.org"]
-
-PORT = 7585892 % 0xFFFF                        # == 49367
+PORT = 4000                            # Default port
 
 def main():
     try:
@@ -43,6 +45,7 @@ def main_thread(port):
     sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     sock.bind(("", port))
     sock.listen(5)
+    print "Listening on port", port, "..."
     while 1:
        (conn, addr) = sock.accept()
        thread.start_new_thread(service_thread, (conn, addr))
@@ -50,26 +53,11 @@ def main_thread(port):
 
 def service_thread(conn, addr):
     (caddr, cport) = addr
-    try:
-       host, aliases, ipaddrs = socket.gethostbyaddr(caddr)
-    except socket.error:
-       print "Don't know hostname for", caddr
-       return
-    if '.' not in host:
-       for a in aliases:
-           if '.' in a:
-               host = a
-               break
-       else:
-           print "Only a local name (%s) for %s" % (host, caddr)
-           return
-    i = string.find(host, '.')
-    domain = string.lower(host[i:])
-    if domain not in OK_DOMAINS:
-       print "Connection from", host, "not accepted"
+    if caddr != socket.gethostbyname(socket.gethostname()):
+       print "Connection from", caddr, "not accepted."
        return
     print "Thread %s has connection from %s.\n" % (str(thread.get_ident()),
-                                                  host),
+                                                  caddr),
     stdin = conn.makefile("r")
     stdout = conn.makefile("w", 0)
     run_interpreter(stdin, stdout)