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..d0bc25784fd63a36cb99dbf288be8b3997ec05cc
--- /dev/null
+++ b/tools/skpdiff/skpdiff_server.py
@@ -0,0 +1,83 @@
+#!/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):

[djsollen, 2013/07/25 12:02:57]

aren't we going to start the server after we know the directories that the
images are in?  Why not pass those params to the server at startup and only
serve from those directories?

[Zach Reizner, 2013/07/25 13:24:46]

Due to the way skpdiff_output.json is structured, the filenames inside it could
be relative or absolute. A future CL will change this behavior because it will
generate its own skpdiff_output.json from images it puts in a directory.
Therefore it will have much better control and knowledge over where the images
are in the filesystem.

+            return
+
+        # If no file to send was found, just give the standard 404
+        self.send_error(404)
+
+
+def main():
+    server_address = ('127.0.0.1', 8080)

[epoger, 2013/07/24 22:00:25]

Please add a note indicating the security problem that will follow if someone
binds to a server_address allowing access from machines other than localhost.

+    http_server = BaseHTTPServer.HTTPServer(server_address, SkPDiffHandler)
+    print('Navigate thine browser to: {}:{}'.format(*server_address))
+    http_server.serve_forever()
+
+if __name__ == '__main__':
+    main()