Crawler backend

sitescripts/crawler/web/crawler.py

-import MySQLdb, os, simplejson
+import MySQLdb, os, re, simplejson, sys
 from sitescripts.utils import cached, get_config
 from sitescripts.web import url_handler, basic_auth
 
 @cached(600)
 def _get_db():
   database = get_config().get("crawler", "database")
   dbuser = get_config().get("crawler", "dbuser")
   dbpasswd = get_config().get("crawler", "dbpassword")
   if os.name == "nt":
-    return MySQLdb.connect(user=dbuser, passwd=dbpasswd, db=database, use_unicode=True, charset="utf8", named_pipe=True)
+    return MySQLdb.connect(user=dbuser, passwd=dbpasswd, db=database,
+                           use_unicode=True, charset="utf8", named_pipe=True)
   else:
-    return MySQLdb.connect(user=dbuser, passwd=dbpasswd, db=database, use_unicode=True, charset="utf8")
+    return MySQLdb.connect(user=dbuser, passwd=dbpasswd, db=database,
+                           use_unicode=True, charset="utf8")
 
 def get_cursor():
   return _get_db().cursor(MySQLdb.cursors.DictCursor)
 
 def _fetch_crawlable_sites():
   cursor = get_cursor()
   cursor.execute("SELECT url from crawler_sites")
   results = cursor.fetchall()
   sites = [result["url"] for result in results]
   return sites
 
 @url_handler("/crawlableSites")
-@basic_auth
+@basic_auth("crawler")
 def crawlable_sites(environ, start_response):
   urls = _fetch_crawlable_sites()
   start_response("200 OK", [("Content-Type", "text/plain")])
   return "\n".join(urls)
 
 def _find_site_id(site_url):
   cursor = get_cursor()
   cursor.execute("SELECT id FROM crawler_sites WHERE url = %s", site_url)
-  return cursor.fetchall()[0]["id"]
+  result = cursor.fetchone()
+  return result["id"] if result else None
 
 def _read_multipart_lines(environ, line_callback):
   data_file = environ["wsgi.input"]
-  current_line = 0
+  content_type = environ.get("CONTENT_TYPE")
+  if not content_type:
+    raise ValueError("Content-Type missing from header")
 
-  while True:
-    line = data_file.readline().strip()
-    current_line += 1
+  match = re.search(r"boundary=(.*)", content_type)
+  if not match:
+    raise ValueError("Multipart form data or boundary declaration missing")
 
-    if current_line == 1:
-      boundary = line
+  boundary = match.group(1)
+  boundary_passed = False
+  header_passed = False
+
+  for line in data_file:
+    line = line.strip()
+
+    if not boundary_passed:
+      if line == "--" + boundary:
+        boundary_passed = True
       continue
 
-    if current_line < 5 or not line:
+    if not header_passed:
+      if not line:
+        header_passed = True
       continue
 
-    if line.startswith(boundary):
+    if line == "--" + boundary + "--":
       break
 
-    line_callback(line)
+    if line:
+      line_callback(line)
 
 def _create_run():
   cursor = get_cursor()
   cursor.execute("INSERT INTO crawler_runs () VALUES ()")
   return cursor.lastrowid
 
 def _insert_data(run_id, site, url, filtered):
   site_id = _find_site_id(site)
+  if site_id is None:
+    print >>sys.stderr, "Unable to find site '%s' in the database" % site
+    return
+
   cursor = get_cursor()
   cursor.execute("""
 INSERT INTO crawler_data (run, site, url, filtered)
 VALUES (%s, %s, %s, %s)""",
-                 (run_id, site_id, url, filtered))  
+                 (run_id, site_id, url, filtered))
 
 @url_handler("/crawlerData")
-@basic_auth
+@basic_auth("crawler")
 def crawler_data(environ, start_response):
   def line_callback(line):
-    url, site, filtered = simplejson.loads(line)
-    _insert_data(run_id, site, url, filtered)
+    try:
+      url, site, filtered = simplejson.loads(line)
+      _insert_data(run_id, site, url, filtered)
+    except simplejson.JSONDecodeError:
+      print >>sys.stderr, "Unable to parse JSON from '%s'" % line
 
   run_id = _create_run()
-  _read_multipart_lines(environ, line_callback)
-  start_response("200 OK", [("Content-Type", "text/plain")])
-  return ""
+  try:
+    _read_multipart_lines(environ, line_callback)
+    start_response("200 OK", [("Content-Type", "text/plain")])
+    return ""
+  except ValueError as e:
+    start_response("401 Bad Request", [("Content-Type", "text/plain")])
+    return e