Switch hosts on HSTS preload to HTTPS (#151)

httpx/models.py

@@ -8,6 +8,7 @@ from http.cookiejar import Cookie, CookieJar
 from urllib.parse import parse_qsl, urlencode
 
 import chardet
+import hstspreload
 import rfc3986
 
 from .config import USER_AGENT
@@ -113,6 +114,14 @@ class URL:
             if not self.host:
                 raise InvalidURL("No host included in URL.")
 
+        # If the URL is HTTP but the host is on the HSTS preload list switch to HTTPS.
+        if (
+            self.scheme == "http"
+            and self.host
+            and hstspreload.in_hsts_preload(self.host)
+        ):
+            self.components = self.components.copy_with(scheme="https")
+
     @property
     def scheme(self) -> str:
         return self.components.scheme or ""

requirements.txt

@@ -2,6 +2,7 @@ certifi
 chardet==3.*
 h11==0.8.*
 h2==3.*
+hstspreload
 idna==2.*
 rfc3986==1.*
 

setup.py

@@ -51,6 +51,7 @@ setup(
         "chardet==3.*",
         "h11==0.8.*",
         "h2==3.*",
+        "hstspreload",
         "idna==2.*",
         "rfc3986==1.*",
     ],

tests/models/test_url.py

@@ -124,3 +124,11 @@ def test_url_set():
     url_set = set(urls)
 
     assert all(url in urls for url in url_set)
+
+
+def test_hsts_preload_converted_to_https():
+    url = URL("http://www.paypal.com")
+
+    assert url.is_ssl
+    assert url.scheme == "https"
+    assert url == "https://www.paypal.com"