[WIP] Adding a TimeTravel improver for nginx

---------------------NOT READY FOR REVIEW YET--------------------

This is not the best way. Maybe we want a generic time travel improver
which could run on multiple data source. This is highly experimental and
is meant to serve as proof of work for current model.
Currently, this is incomplete and doesn't work. The classes and
functions used in time travel have not been ported properly.

This commit might need a full rewrite

Signed-off-by: Hritik Vijay <hritikxx8@gmail.com>

vulnerabilities/helpers.py

@@ -124,7 +124,7 @@ def requests_with_5xx_retry(max_retries=5, backoff_factor=0.5):
 
 def nearest_patched_package(
     vulnerable_packages: List[PackageURL], resolved_packages: List[PackageURL]
-) -> List[AffectedPackage]:
+) -> List[Tuple]:
     class PackageURLWithVersionComparator:
         """
         This class is used to  get around bisect module's lack of supplying custom
@@ -158,11 +158,12 @@ def __lt__(self, other):
         if patched_package_index < resolved_package_count:
             patched_package = resolved_packages[patched_package_index].package
 
-        affected_package_with_patched_package_objects.append(
-            AffectedPackage(
-                vulnerable_package=vulnerable_package.package, patched_package=patched_package
-            )
-        )
+#        affected_package_with_patched_package_objects.append(
+#            AffectedPackage(
+#                vulnerable_package=vulnerable_package.package, patched_package=patched_package
+#            )
+#        )
+        affected_package_with_patched_package_objects.append((vulnerable_package.package, patched_package))
 
     return affected_package_with_patched_package_objects
 

vulnerabilities/importers/nginx.py

@@ -36,10 +36,12 @@
 from vulnerabilities.data_source import DataSource
 from vulnerabilities.data_source import DataSourceConfiguration
 from vulnerabilities.data_source import Reference
+from vulnerabilities.data_inference import Inference
+from vulnerabilities.data_inference import Improver
 from vulnerabilities.package_managers import GitHubTagsAPI
 from vulnerabilities.package_managers import Version
 from vulnerabilities.helpers import nearest_patched_package
-
+from vulnerabilities.models import Advisory
 
 @dataclasses.dataclass
 class NginxDataSourceConfiguration(DataSourceConfiguration):
@@ -51,21 +53,6 @@ class NginxDataSource(DataSource):
 
     url = "http://nginx.org/en/security_advisories.html"
 
-    def set_api(self):
-        self.version_api = GitHubTagsAPI()
-        asyncio.run(self.version_api.load_api(["nginx/nginx"]))
-
-        # For some reason nginx tags it's releases are in the form of `release-1.2.3`
-        # Chop off the `release-` part here.
-        normalized_versions = set()
-        while self.version_api.cache["nginx/nginx"]:
-            version = self.version_api.cache["nginx/nginx"].pop()
-            normalized_version = Version(
-                version.value.replace("release-", ""), version.release_date
-            )
-            normalized_versions.add(normalized_version)
-        self.version_api.cache["nginx/nginx"] = normalized_versions
-
     def advisory_data(self) -> List[AdvisoryData]:
         adv_data = []
         #        self.set_api()
@@ -170,7 +157,9 @@ def extract_vuln_pkgs(self, vuln_info):
             if "-" not in version_info:
                 # These are discrete versions
                 version_ranges.append(
-                    VersionSpecifier.from_scheme_version_spec_string("semver", version_info[0])
+                    VersionSpecifier.from_scheme_version_spec_string(
+                        "semver", version_info[0]
+                    )
                 )
                 continue
 
@@ -195,6 +184,67 @@ def extract_vuln_pkgs(self, vuln_info):
         ]
 
 
+class NginxTimeTravel(Improver):
+    def inferences(self):
+        self.set_api()
+        advisories = Advisory.objects.filter(
+            source="vulnerabilities.importers.nginx.NginxDataSource"
+        )
+        inferences = []
+        for advisory in advisories:
+            advisory_data = AdvisoryData.from_json(advisory.data)
+
+            affected_package_ranges = [
+                pkg.version_specifier for pkg in advisory_data.affected_packages
+            ]
+            affected_package_versions = find_valid_versions(
+                self.version_api.get("nginx/nginx").valid_versions,
+                affected_package_ranges,
+            )
+            affected_packages = []
+            for pkg in advisory_data.affected_packages:
+                for 
+                affected_packages.extend([])
+            affected_packages = [advisory_data.affected_packages]
+
+            fixed_package_ranges = [
+                pkg.version_specifier for pkg in advisory_data.affected_packages
+            ]
+            fixed_packages = find_valid_versions(
+                self.version_api.get("nginx/nginx").valid_versions, fixed_package_ranges
+            )
+
+            pkgs = nearest_patched_package(affected_package_versions, fixed_package_ranges)
+            for pkg in pkgs:
+                print(pkg)
+                print(type(pkg))
+                inferences.append(
+                    Inference(
+                        confidence=90,  # TODO: Decide properly
+                        vulnerability_id=advisory_data.vulnerability_id,
+                        affected_packages=pkg[0],
+                        fixed_packages=pkg[1],
+                    )
+                )
+
+            return inferences
+
+    def set_api(self):
+        self.version_api = GitHubTagsAPI()
+        asyncio.run(self.version_api.load_api(["nginx/nginx"]))
+
+        # For some reason nginx tags it's releases are in the form of `release-1.2.3`
+        # Chop off the `release-` part here.
+        normalized_versions = set()
+        while self.version_api.cache["nginx/nginx"]:
+            version = self.version_api.cache["nginx/nginx"].pop()
+            normalized_version = Version(
+                version.value.replace("release-", ""), version.release_date
+            )
+            normalized_versions.add(normalized_version)
+        self.version_api.cache["nginx/nginx"] = normalized_versions
+
+
 def find_valid_versions(versions, version_ranges):
     valid_versions = set()
     for version in versions:

vulnerabilities/improvers/__init__.py

@@ -1,6 +1,10 @@
+from vulnerabilities import importers
 from . import nginx
 from . import default
 
-IMPROVER_REGISTRY = [default.DefaultImprover]
+IMPROVER_REGISTRY = [
+    default.DefaultImprover,
+    importers.nginx.NginxTimeTravel,
+]
 
 improver_mapping = {f"{x.__module__}.{x.__name__}": x for x in IMPROVER_REGISTRY}