add basic HTTP server for viewing skpdiff results

tools/skpdiff/skpdiff_server.py

Index: tools/skpdiff/skpdiff_server.py
diff --git a/tools/skpdiff/skpdiff_server.py b/tools/skpdiff/skpdiff_server.py
new file mode 100644
index 0000000000000000000000000000000000000000..07f0e53af3633eca14c35dadb15d764bdc43e422
--- /dev/null
+++ b/tools/skpdiff/skpdiff_server.py
@@ -0,0 +1,87 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+from __future__ import print_function
+import BaseHTTPServer
+import os
+import os.path
+
+# A simple dictionary of file name extensions to MIME types. The empty string
+# entry is used as the default when no extension was given or if the extension
+# has no entry in this dictionary.
+MIME_TYPE_MAP = {'': 'application/octet-stream',
+                 'html': 'text/html',
+                 'css': 'text/css',
+                 'png': 'image/png',
+                 'js': 'application/javascript'
+                 }
+
+
+class SkPDiffHandler(BaseHTTPServer.BaseHTTPRequestHandler):
+    def send_file(self, file_path):
+        # Grab the extension if there is one
+        extension = os.path.splitext(file_path)[1]
+        if len(extension) >= 1:
+            extension = extension[1:]
+
+        # Determine the MIME type of the file from its extension
+        mime_type = MIME_TYPE_MAP.get(extension, MIME_TYPE_MAP[''])
+
+        # Open the file and send it over HTTP
+        sending_file = open(file_path, 'rb')
+        self.send_response(200)
+        self.send_header('Content-type', mime_type)
+        self.end_headers()
+        self.wfile.write(sending_file.read())
+        sending_file.close()
+
+    def serve_if_in_dir(self, dir_path, file_path):
+        # Determine if the file exists relative to the given dir_path AND exists
+        # under the dir_path. This is to prevent accidentally serving files
+        # outside the directory intended using symlinks, or '../'.
+        real_path = os.path.normpath(os.path.join(dir_path, file_path))
+        print(repr(real_path))
+        if os.path.commonprefix([real_path, dir_path]) == dir_path:
+            if os.path.isfile(real_path):
+                self.send_file(real_path)
+                return True
+        return False
+
+    def do_GET(self):
+        # Grab the script path because that is where all the static assets are
+        script_dir = os.path.dirname(os.path.abspath(__file__))
+
+        # Simple rewrite rule of the root path to 'viewer.html'
+        if self.path == '' or self.path == '/':
+            self.path = '/viewer.html'
+
+        # The [1:] chops off the leading '/'
+        file_path = self.path[1:]
+
+        # Attempt to send static asset files first
+        if self.serve_if_in_dir(script_dir, file_path):
+            return
+
+        # WARNING: Using the root is a big ol' hack. Incredibly insecure. Only
+        # allow serving to localhost unless you want the network to be able to
+        # see ALL of the files you can.
+        # Attempt to send gm image files
+        if self.serve_if_in_dir('/', file_path):
+            return
+
+        # If no file to send was found, just give the standard 404
+        self.send_error(404)
+
+
+def main():
+    # Do not bind to interfaces other than localhost because the server will
+    # attempt to serve files relative to the root directory as a last resort
+    # before 404ing. This means all of your files can be accessed from this
+    # server, so DO NOT let this server listen to anything but localhost.
+    server_address = ('127.0.0.1', 8080)
+    http_server = BaseHTTPServer.HTTPServer(server_address, SkPDiffHandler)
+    print('Navigate thine browser to: {}:{}'.format(*server_address))
+    http_server.serve_forever()
+
+if __name__ == '__main__':
+    main()