From ae97094f215b757a9e80d6b4463cd670bfcb5860 Mon Sep 17 00:00:00 2001
From: Dan Johnson <computerdruid@google.com>
Date: Thu, 5 Sep 2019 13:21:45 -0700
Subject: [PATCH 1/2] Allow % in IPv6 addresses to support zone identifiers.

https://tools.ietf.org/html/rfc6874 explains that %25 can be used to
indicate a "zone identifier", useful for IPv6 link-local addresses.
---
 src/uri/authority.rs | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/uri/authority.rs b/src/uri/authority.rs
index 724712cc..7088b8c6 100644
--- a/src/uri/authority.rs
+++ b/src/uri/authority.rs
@@ -103,15 +103,20 @@ impl Authority {
                 }
                 b':' => {
                     colon_cnt += 1;
-                },
+                }
                 b'[' => {
                     start_bracket = true;
+                    if has_percent {
+                        // Something other than the userinfo has a `%`, so reject it.
+                        return Err(ErrorKind::InvalidAuthority.into());
+                    }
                 }
                 b']' => {
                     end_bracket = true;
 
                     // Those were part of an IPv6 hostname, so forget them...
                     colon_cnt = 0;
+                    has_percent = false;
                 }
                 b'@' => {
                     at_sign_pos = Some(i);
@@ -127,8 +132,11 @@ impl Authority {
                     // the userinfo can have a percent-encoded username and password,
                     // so record that a `%` was found. If this turns out to be
                     // part of the userinfo, this flag will be cleared.
+                    // Also per https://tools.ietf.org/html/rfc6874, percent-encoding can
+                    // be used to indicate a zone identifier.
                     // If the flag hasn't been cleared at the end, that means this
-                    // was part of the hostname, and will fail with an error.
+                    // was part of the hostname (and not part of an IPv6 address), and
+                    // will fail with an error.
                     has_percent = true;
                 }
                 0 => {
@@ -612,4 +620,11 @@ mod tests {
         let err = Authority::parse_non_empty(b"a%2f:b%2f@example%2f.com").unwrap_err();
         assert_eq!(err.0, ErrorKind::InvalidAuthority);
     }
+
+    #[test]
+    fn allows_percent_in_ipv6_address() {
+        let authority_str = "[fe80::1:2:3:4%25eth0]";
+        let result: Authority = authority_str.parse().unwrap();
+        assert_eq!(result, authority_str);
+    }
 }

From d674788393af80d26c954aaeb600c2e3f37c753f Mon Sep 17 00:00:00 2001
From: Dan Johnson <computerdruid@google.com>
Date: Fri, 13 Sep 2019 10:28:39 -0700
Subject: [PATCH 2/2] Add test case for % outside of IPv6 address

---
 src/uri/authority.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/uri/authority.rs b/src/uri/authority.rs
index 7088b8c6..0564f2b5 100644
--- a/src/uri/authority.rs
+++ b/src/uri/authority.rs
@@ -627,4 +627,13 @@ mod tests {
         let result: Authority = authority_str.parse().unwrap();
         assert_eq!(result, authority_str);
     }
+
+    #[test]
+    fn rejects_percent_outside_ipv6_address() {
+        let err = Authority::parse_non_empty(b"1234%20[fe80::1:2:3:4]").unwrap_err();
+        assert_eq!(err.0, ErrorKind::InvalidAuthority);
+
+        let err = Authority::parse_non_empty(b"[fe80::1:2:3:4]%20").unwrap_err();
+        assert_eq!(err.0, ErrorKind::InvalidAuthority);
+    }
 }