Add Windows named-pipe local control

crates/geth-config/src/lib.rs

@@ -87,7 +87,23 @@ impl GethPaths {
 
     #[must_use]
     pub fn socket_path(&self) -> PathBuf {
-        self.run_dir().join("geth.sock")
+        PathBuf::from(self.control_endpoint())
+    }
+
+    #[must_use]
+    pub fn control_endpoint(&self) -> String {
+        #[cfg(unix)]
+        {
+            self.run_dir().join("geth.sock").display().to_string()
+        }
+        #[cfg(windows)]
+        {
+            let home = self.home.display().to_string().to_ascii_lowercase();
+            format!(
+                r"\\.\pipe\geth-{:016x}",
+                stable_control_endpoint_suffix(home.as_bytes())
+            )
+        }
     }
 
     pub fn ensure_base_dirs(&self) -> Result<(), ConfigError> {
@@ -98,6 +114,16 @@ impl GethPaths {
     }
 }
 
+#[cfg(any(windows, test))]
+fn stable_control_endpoint_suffix(bytes: &[u8]) -> u64 {
+    let mut hash = 0xcbf2_9ce4_8422_2325_u64;
+    for byte in bytes {
+        hash ^= u64::from(*byte);
+        hash = hash.wrapping_mul(0x0000_0100_0000_01b3);
+    }
+    hash
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum ConfigError {
     #[error("could not determine OS data directory and GETH_HOME is unset")]
@@ -603,6 +629,18 @@ mod tests {
         assert!(matches!(error, ConfigError::InvalidLocalDiscovery(_)));
     }
 
+    #[test]
+    fn control_endpoint_suffix_is_stable_and_home_scoped() {
+        assert_eq!(
+            stable_control_endpoint_suffix(b"C:/Users/Eric/geth"),
+            stable_control_endpoint_suffix(b"C:/Users/Eric/geth")
+        );
+        assert_ne!(
+            stable_control_endpoint_suffix(b"C:/Users/Eric/geth"),
+            stable_control_endpoint_suffix(b"C:/Users/Eric/other")
+        );
+    }
+
     #[test]
     fn config_set_preserves_comments_and_validates_the_result() {
         let home = tempfile::tempdir().expect("tempdir");