add cache to document loader

pyvckit/document_loader.py

@@ -0,0 +1,127 @@
+"""
+Remote document loader using Requests.
+
+.. module:: jsonld.documentloader.requests
+  :synopsis: Remote document loader using Requests
+
+.. moduleauthor:: Dave Longley
+.. moduleauthor:: Mike Johnson
+.. moduleauthor:: Tim McNamara <tim.mcnamara@okfn.org>
+.. moduleauthor:: Olaf Conradi <olaf@conradi.org>
+"""
+import string
+import json
+import urllib.parse as urllib_parse
+
+from pyld.jsonld import (JsonLdError, parse_link_header, LINK_HEADER_REL)
+
+
+def get_cache():
+    with open("cache_context.json") as f:
+        doc_str = f.read()
+        if doc_str:
+            # import pdb; pdb.set_trace()
+            return json.loads(doc_str)
+    return {}
+
+
+def requests_document_loader(secure=False, **kwargs):
+    """
+    Create a Requests document loader.
+
+    Can be used to setup extra Requests args such as verify, cert, timeout,
+    or others.
+
+    :param secure: require all requests to use HTTPS (default: False).
+    :param **kwargs: extra keyword args for Requests get() call.
+
+    :return: the RemoteDocument loader function.
+    """
+    import requests
+
+
+    def loader(url, options={}):
+        """
+        Retrieves JSON-LD at the given URL.
+
+        :param url: the URL to retrieve.
+
+        :return: the RemoteDocument.
+        """
+        # import pdb; pdb.set_trace()
+        cache = get_cache()
+        if cache.get(url):
+            return cache[url]
+
+        try:
+            # validate URL
+            pieces = urllib_parse.urlparse(url)
+            if (not all([pieces.scheme, pieces.netloc]) or
+                pieces.scheme not in ['http', 'https'] or
+                set(pieces.netloc) > set(
+                    string.ascii_letters + string.digits + '-.:')):
+                raise JsonLdError(
+                    'URL could not be dereferenced; only "http" and "https" '
+                    'URLs are supported.',
+                    'jsonld.InvalidUrl', {'url': url},
+                    code='loading document failed')
+            if secure and pieces.scheme != 'https':
+                raise JsonLdError(
+                    'URL could not be dereferenced; secure mode enabled and '
+                    'the URL\'s scheme is not "https".',
+                    'jsonld.InvalidUrl', {'url': url},
+                    code='loading document failed')
+            headers = options.get('headers')
+            if headers is None:
+                headers = {
+                    'Accept': 'application/ld+json, application/json'
+                }
+            response = requests.get(url, headers=headers, **kwargs)
+
+            content_type = response.headers.get('content-type')
+            if not content_type:
+                content_type = 'application/octet-stream'
+            doc = {
+                'contentType': content_type,
+                'contextUrl': None,
+                'documentUrl': response.url,
+                'document': response.json()
+            }
+            link_header = response.headers.get('link')
+            if link_header:
+                linked_context = parse_link_header(link_header).get(
+                    LINK_HEADER_REL)
+                # only 1 related link header permitted
+                if linked_context and content_type != 'application/ld+json':
+                  if isinstance(linked_context, list):
+                      raise JsonLdError(
+                          'URL could not be dereferenced, '
+                          'it has more than one '
+                          'associated HTTP Link Header.',
+                          'jsonld.LoadDocumentError',
+                          {'url': url},
+                          code='multiple context link headers')
+                  doc['contextUrl'] = linked_context['target']
+                linked_alternate = parse_link_header(link_header).get('alternate')
+                # if not JSON-LD, alternate may point there
+                if (linked_alternate and
+                        linked_alternate.get('type') == 'application/ld+json' and
+                        not re.match(r'^application\/(\w*\+)?json$', content_type)):
+                    doc['contentType'] = 'application/ld+json'
+                    doc['documentUrl'] = jsonld.prepend_base(url, linked_alternate['target'])
+            # import pdb; pdb.set_trace()
+            cache[url] = doc
+            f = open("cache_context.json", "w")
+            f.write(json.dumps(cache))
+            f.close()
+            return doc
+        except JsonLdError as e:
+            raise e
+        except Exception as cause:
+            raise JsonLdError(
+                'Could not retrieve a JSON-LD document from the URL.',
+                'jsonld.LoadDocumentError', code='loading document failed',
+                cause=cause)
+
+    return loader
+

pyvckit/sign.py

@@ -2,6 +2,10 @@ import hashlib
 import nacl.signing
 import nacl.encoding
 from pyld import jsonld
+from pyvckit.document_loader import requests_document_loader
+
+
+jsonld.set_document_loader(requests_document_loader())
 
 
 # https://github.com/spruceid/ssi/blob/main/ssi-jws/src/lib.rs#L75