[analyzer] Open server on IPv6 when available (#158).

This commit makes ikos-scan and ikos-view use IPv6 when available. More
specifically, it replaces uses of HTTPServer, which by default only
listens on IPv4 interfaces, with calls to a custom class HTTPServerIPv6.
The latter listens on IPv6 when available, as well as IPv4 whenever
dual-stack is supported. If IPv6 is not available, the server defaults
to the old behavior implemented by HTTPServer.

analyzer/python/ikos/scan.py

@@ -641,8 +641,8 @@ def __init__(self):
             try:
                 # try to start the http server on a random port
                 self.port = random.randint(8000, 9000)
-                self.httpd = http.HTTPServer(('', self.port),
-                                             ScanServerRequestHandler)
+                self.httpd = http.HTTPServerIPv6(('', self.port),
+                                                 ScanServerRequestHandler)
             except (OSError, IOError):
                 self.port = None  # port already in use
 

analyzer/python/ikos/view.py

@@ -62,7 +62,7 @@
 from ikos import settings
 from ikos.enums import Result, CheckKind
 from ikos.highlight import CppLexer, HtmlFormatter, highlight
-from ikos.http import HTTPServer, BaseHTTPRequestHandler
+from ikos.http import HTTPServerIPv6, BaseHTTPRequestHandler
 from ikos.log import printf
 from ikos.output_db import OutputDatabase
 
@@ -337,7 +337,7 @@ def __init__(self, db, port=8080):
         self.report = ViewReport(self.db)
 
         try:
-            self.httpd = HTTPServer(('', self.port), RequestHandler)
+            self.httpd = HTTPServerIPv6(('', self.port), RequestHandler)
         except (OSError, IOError) as e:
             log.error("Could not start the HTTP server: %s" % e)
             sys.exit(1)