net: Keep IP cookie buckets separate (#44152)

Use the full IP address as the cookie storage bucket key instead of
passing IP hosts through the public suffix registrable-domain helper.
This prevents unrelated IP hosts that share suffix-like address segments
from sharing a per-host eviction bucket.

Testing: Added `test_ip_cookie_bucket_collision_eviction`; ran `cargo
test -p servo-net --test main test_ip_cookie_bucket_collision_eviction
--locked`.
Fixes: #44097

---------

Signed-off-by: Asish Kumar <officialasishkumar@gmail.com>

components/net/cookie_storage.rs

@@ -8,6 +8,7 @@
 use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::collections::hash_map::Entry;
+use std::net::IpAddr;
 use std::time::SystemTime;
 
 use cookie::Cookie;
@@ -292,6 +293,14 @@ impl CookieStorage {
 }
 
 fn reg_host(url: &str) -> String {
+    let host_for_ip_parse = url
+        .strip_prefix('[')
+        .and_then(|url| url.strip_suffix(']'))
+        .unwrap_or(url);
+    if let Ok(address) = host_for_ip_parse.parse::<IpAddr>() {
+        return address.to_string().to_lowercase();
+    }
+
     reg_suffix(url).to_lowercase()
 }
 

components/net/tests/cookie.rs

@@ -222,6 +222,36 @@ fn add_cookie_to_storage(storage: &mut CookieStorage, url: &ServoUrl, cookie_str
     storage.push(cookie, url, source);
 }
 
+fn assert_ip_cookie_bucket_collision_eviction(ip_a: &str, ip_b: &str) {
+    let mut storage = CookieStorage::new(5);
+    let ip_a = ServoUrl::parse(ip_a).unwrap();
+    let ip_b = ServoUrl::parse(ip_b).unwrap();
+    let source = CookieSource::HTTP;
+
+    for i in 1..=3 {
+        add_cookie_to_storage(&mut storage, &ip_a, &format!("a{i}=val{i}"));
+    }
+
+    for i in 1..=5 {
+        add_cookie_to_storage(&mut storage, &ip_b, &format!("b{i}=val{i}"));
+    }
+
+    let cookies_a = storage.cookies_for_url(&ip_a, source).unwrap();
+    assert_eq!(cookies_a.split("; ").count(), 3);
+    for i in 1..=3 {
+        assert!(cookies_a.contains(&format!("a{i}=val{i}")));
+    }
+}
+
+#[test]
+fn test_ip_cookie_bucket_collision_eviction() {
+    assert_ip_cookie_bucket_collision_eviction("http://192.168.0.1/path", "http://10.0.0.1/path");
+    assert_ip_cookie_bucket_collision_eviction(
+        "http://[2001:db8::1]/path",
+        "http://[2001:db8::2]/path",
+    );
+}
+
 #[test]
 fn test_insecure_cookies_cannot_evict_secure_cookie() {
     let mut storage = CookieStorage::new(5);