[fix]soundcloud.com guest client_id fetches dynamically

searx/engines/soundcloud.py

@@ -10,17 +10,19 @@
  @parse       url, title, content, publishedDate, embedded
 """
 
+import re
+from StringIO import StringIO
 from json import loads
+from lxml import etree
 from urllib import urlencode, quote_plus
 from dateutil import parser
+from searx import logger
+from searx.poolrequests import get as http_get
 
 # engine dependent config
 categories = ['music']
 paging = True
 
-# api-key
-guest_client_id = 'b45b1aa10f1ac2941910a7f0d10f8e28'
-
 # search-url
 url = 'https://api.soundcloud.com/'
 search_url = url + 'search?{query}'\
@@ -35,6 +37,30 @@ embedded_url = '<iframe width="100%" height="166" ' +\
     'data-src="https://w.soundcloud.com/player/?url={uri}"></iframe>'
 
 
+def get_client_id():
+    response = http_get("https://soundcloud.com")
+    rx_namespace = {"re": "http://exslt.org/regular-expressions"}
+
+    if response.ok:
+        tree = etree.parse(StringIO(response.content), etree.HTMLParser())
+        script_tags = tree.xpath("//script[re:match(@src, '(.*app.*js)')]", namespaces=rx_namespace)
+        app_js_urls = [script_tag.get('src') for script_tag in script_tags if script_tag is not None]
+
+        # extracts valid app_js urls from soundcloud.com content
+        for app_js_url in app_js_urls:
+            # gets app_js and searches for the clientid
+            response = http_get(app_js_url)
+            if response.ok:
+                cids = re.search(r'client_id:"([^"]*)"', response.content, re.M | re.I)
+                if cids is not None and len(cids.groups()):
+                    return cids.groups()[0]
+    logger.warning("Unable to fetch guest client_id from SoundCloud, check parser!")
+    return ""
+
+# api-key
+guest_client_id = get_client_id()
+
+
 # do search-request
 def request(query, params):
     offset = (params['pageno'] - 1) * 20