Add response error message output to HTTP Status 401 Errors in FileDo…

…wnloader (#15983)

* add missing test dependencies PyJWT and pluginbase

* add tests for unauthorized downloads due to missing or bad credentials

Also change the TestFileServer to distinguish between the two cases
so that we can test them by replacing the bad credentials error
message "Not authorized" with "Bad credentials".

* add response error message to 401 error in file downloader

The source download step attempts to load source_credentials.json when it is present.
When following the recommended steps of passing credentials to the source_credentials.json via
os.getenv('BACKUP_USER') etc., this can result in the json string "None" when
no authentication is provided.
This effectively gets translated to the curl call when being read:

    curl -i -u None:None https://artifactory.example.org/artifactory/source-backup/

This causes an error with status code 401, which currently does not propagate
the error message and is slightly misleading, as a source_credentials.json is
provided but the content is wrong:

    ERROR: conanfile.py (example/1.0): Error in source() method, line 17
            get(self, self.url, sha256=sha256, strip_root=True)
            ConanException: The source backup server 'https://artifactory.example.org/artifactory/source-backup/' needs authentication: . Please provide 'source_credentials.json'

With this fix, the error message is propagated in the same way others in the
same block, resulting in a more useful message, although the "please provide"
is still misleading.

    ERROR: conanfile.py (example/1.0): Error in source() method, line 17
            get(self, self.url, sha256=sha256, strip_root=True)
            ConanException: The source backup server 'https://artifactory.example.org/artifactory/source-backup/' needs authentication: {
  "errors" : [ {
    "status" : 401,
    "message" : "Bad credentials"
  } ]
}. Please provide 'source_credentials.json'

conans/client/downloaders/file_downloader.py

@@ -86,7 +86,7 @@ def _download_file(self, url, auth, headers, file_path, verify_ssl, try_resume=F
                     raise AuthenticationException(response_to_str(response))
                 raise ForbiddenException(response_to_str(response))
             elif response.status_code == 401:
-                raise AuthenticationException()
+                raise AuthenticationException(response_to_str(response))
             raise ConanException("Error %d downloading file %s" % (response.status_code, url))
 
         def get_total_length():

conans/requirements_dev.txt

@@ -4,3 +4,5 @@ parameterized>=0.6.3
 mock>=1.3.0, <1.4.0
 WebTest>=2.0.18, <2.1.0
 bottle
+PyJWT
+pluginbase

conans/test/unittests/tools/files/test_downloads.py

@@ -77,6 +77,27 @@ def test_download_forbidden(self, _manual):
             download(conanfile, file_server.fake_url + "/forbidden", dest)
         assert "403 Forbidden" in str(exc.value)
 
+    def test_download_unauthorized_no_credentials(self, _manual):
+        conanfile, file_server = _manual
+        dest = os.path.join(temp_folder(), "manual.html")
+        # Not authorized without credentials
+        with pytest.raises(AuthenticationException) as exc:
+            download(conanfile, file_server.fake_url + "/basic-auth/manual.html", dest)
+        assert "401 Unauthorized" in str(exc.value)
+        assert "Not authorized" in str(exc.value)
+
+    def test_download_unauthorized_literal_none_credentials(self, _manual):
+        conanfile, file_server = _manual
+        dest = os.path.join(temp_folder(), "manual.html")
+        # os.getenv('SOME_UNSET_VARIABLE') causes source_credentials.json to contain
+        # "None" as a string literal, causing auth to be ("None", "None") or with
+        # a "None" token.
+        auth = ("None", "None")
+        with pytest.raises(AuthenticationException) as exc:
+            download(conanfile, file_server.fake_url + "/basic-auth/manual.html", dest, auth=auth)
+        assert "401 Unauthorized" in str(exc.value)
+        assert "Bad credentials" in str(exc.value)
+
     def test_download_authorized(self, _manual):
         conanfile, file_server = _manual
         dest = os.path.join(temp_folder(), "manual.html")

conans/test/utils/file_server.py

@@ -50,7 +50,7 @@ def get_user_passwd(file):
             auth = bottle.request.auth
             if auth is not None:
                 if auth != ("user", "password"):
-                    return bottle.HTTPError(401, "Not authorized")
+                    return bottle.HTTPError(401, "Bad credentials")
                 return bottle.static_file(file, store)
 
             auth = bottle.request.headers.get("Authorization")