Implement URL normalization for proxy server URL comparison.

cli/internal/tygerproxy/tygerproxy.go

@@ -189,13 +189,29 @@ func CheckProxyAlreadyRunning(options *ProxyOptions) (*ProxyServiceMetadata, err
 		return existingProxy, ErrProxyNotRunning
 	}
 
-	if existingProxy.ServerUrl != options.ServerUrl {
+	if !urlsEquivalent(existingProxy.ServerUrl, options.ServerUrl) {
 		return existingProxy, ErrProxyAlreadyRunningWrongTarget
 	}
 
 	return existingProxy, nil
 }
 
+func urlsEquivalent(a, b string) bool {
+	return normalizeUrl(a) == normalizeUrl(b)
+}
+
+func normalizeUrl(raw string) string {
+	u, err := url.Parse(raw)
+	if err != nil {
+		return raw
+	}
+	u.Scheme = strings.ToLower(u.Scheme)
+	u.Host = strings.ToLower(u.Host)
+	u.Path = strings.TrimRight(u.Path, "/")
+	u.RawQuery = u.Query().Encode()
+	return u.String()
+}
+
 func GetExistingProxyMetadata(options *ProxyOptions) *ProxyServiceMetadata {
 	// note: not using retryablehttp here because we are hitting localhost
 	// and we want to fail quickly

cli/internal/tygerproxy/tygerproxy_test.go

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+package tygerproxy
+
+import "testing"
+
+func TestUrlsEquivalent(t *testing.T) {
+	tests := []struct {
+		name string
+		a    string
+		b    string
+		want bool
+	}{
+		{"identical", "http://myserver:8080", "http://myserver:8080", true},
+		{"scheme casing", "http://myserver:8080", "HTTP://myserver:8080", true},
+		{"host casing", "http://MyServer:8080", "http://myserver:8080", true},
+		{"mixed case scheme and host", "HTTPS://MyServer.Example.COM/api", "https://myserver.example.com/api", true},
+		{"escaped vs unescaped brackets in query",
+			"ssh://user@myhost/opt/tyger/api.sock?option[StrictHostKeyChecking]=no&option[UserKnownHostsFile]=NUL",
+			"ssh://user@myhost/opt/tyger/api.sock?option%5BStrictHostKeyChecking%5D=no&option%5BUserKnownHostsFile%5D=NUL",
+			true},
+		{"escaped vs unescaped brackets reversed",
+			"ssh://user@myhost/opt/tyger/api.sock?option%5BStrictHostKeyChecking%5D=no&option%5BUserKnownHostsFile%5D=NUL",
+			"ssh://user@myhost/opt/tyger/api.sock?option[StrictHostKeyChecking]=no&option[UserKnownHostsFile]=NUL",
+			true},
+		{"different servers", "http://server-a:8080", "http://server-b:8080", false},
+		{"different ports", "http://myserver:8080", "http://myserver:9090", false},
+		{"different schemes", "http://myserver:8080", "https://myserver:8080", false},
+		{"different query values",
+			"ssh://user@myhost/opt/tyger/api.sock?option[StrictHostKeyChecking]=no",
+			"ssh://user@myhost/opt/tyger/api.sock?option[StrictHostKeyChecking]=yes",
+			false},
+		{"different paths", "http://myserver:8080/a", "http://myserver:8080/b", false},
+		{"trailing slash", "http://myserver:8080/api/", "http://myserver:8080/api", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := urlsEquivalent(tt.a, tt.b)
+			if got != tt.want {
+				t.Errorf("UrlsEquivalent(%q, %q) = %v, want %v", tt.a, tt.b, got, tt.want)
+			}
+		})
+	}
+}