add user-agent tests

reseed/user_agent_test.go

@@ -0,0 +1,138 @@
+package reseed
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+// Test for Bug #6: User Agent String Mismatch with I2P Compatibility
+// This test verifies that the server strictly enforces the exact I2P user agent
+// Only "Wget/1.11.4" is allowed - no other versions or variations
+func TestUserAgentCompatibility(t *testing.T) {
+	// Create a simple handler that just returns OK
+	testHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("OK"))
+	})
+
+	// Wrap with our verification middleware
+	handler := verifyMiddleware(testHandler)
+
+	testCases := []struct {
+		name           string
+		userAgent      string
+		expectedStatus int
+		description    string
+	}{
+		{
+			name:           "Exact match (current behavior)",
+			userAgent:      "Wget/1.11.4",
+			expectedStatus: http.StatusOK,
+			description:    "Should accept the exact expected user agent",
+		},
+		{
+			name:           "Newer wget version",
+			userAgent:      "Wget/1.12.0",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject newer wget versions - only exact I2P standard allowed",
+		},
+		{
+			name:           "Much newer wget version",
+			userAgent:      "Wget/1.20.3",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject much newer wget versions - only exact I2P standard allowed",
+		},
+		{
+			name:           "Invalid user agent (not wget)",
+			userAgent:      "Mozilla/5.0 (Windows NT 10.0; Win64; x64)",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject non-wget user agents",
+		},
+		{
+			name:           "Invalid user agent (curl)",
+			userAgent:      "curl/7.68.0",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject curl and other non-wget agents",
+		},
+		{
+			name:           "Malformed wget version",
+			userAgent:      "Wget/invalid",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject malformed wget versions",
+		},
+		{
+			name:           "Empty user agent",
+			userAgent:      "",
+			expectedStatus: http.StatusForbidden,
+			description:    "Should reject empty user agent",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := httptest.NewRequest("GET", "/i2pseeds.su3", nil)
+			req.Header.Set("User-Agent", tc.userAgent)
+
+			rr := httptest.NewRecorder()
+			handler.ServeHTTP(rr, req)
+
+			if rr.Code != tc.expectedStatus {
+				t.Errorf("Expected status %d, got %d for user agent %q. %s",
+					tc.expectedStatus, rr.Code, tc.userAgent, tc.description)
+			}
+
+			// Log the current behavior for visibility
+			if tc.expectedStatus == http.StatusForbidden && rr.Code == http.StatusForbidden {
+				t.Logf("BLOCKED (as expected): %s -> %d", tc.userAgent, rr.Code)
+			} else if tc.expectedStatus == http.StatusOK && rr.Code == http.StatusOK {
+				t.Logf("ALLOWED (as expected): %s -> %d", tc.userAgent, rr.Code)
+			} else {
+				t.Logf("MISMATCH: %s -> %d (expected %d)", tc.userAgent, rr.Code, tc.expectedStatus)
+			}
+		})
+	}
+}
+
+// isValidI2PUserAgent validates if a user agent string is the exact I2P-required user agent
+// According to I2P protocol specification, ONLY "Wget/1.11.4" is valid for SU3 bundle fetching
+func isValidI2PUserAgent(userAgent string) bool {
+	// I2P protocol requires exactly "Wget/1.11.4" - no other versions or variations allowed
+	return userAgent == I2pUserAgent
+}
+
+// Test for the strict user agent validation (I2P protocol requirement)
+func TestStrictUserAgentValidation(t *testing.T) {
+	testCases := []struct {
+		userAgent    string
+		shouldAccept bool
+		description  string
+	}{
+		{"Wget/1.11.4", true, "Only valid I2P user agent"},
+		{"Wget/1.12.0", false, "Newer version not allowed"},
+		{"Wget/1.20.3", false, "Much newer version not allowed"},
+		{"Wget/2.0.0", false, "Major version upgrade not allowed"},
+		{"wget/1.11.4", false, "Lowercase wget (case sensitive)"},
+		{"Wget/1.11", false, "Missing patch version"},
+		{"Wget/1.11.4.5", false, "Too many version parts"},
+		{"Wget/1.11.4-ubuntu", false, "Version with suffix"},
+		{"Wget/abc", false, "Non-numeric version"},
+		{"Mozilla/5.0", false, "Browser user agent"},
+		{"curl/7.68.0", false, "Curl user agent"},
+		{"", false, "Empty user agent"},
+		{"Wget", false, "No version"},
+		{"Wget/", false, "Empty version"},
+		{"Wget/1.11.3", false, "Older version not allowed"},
+		{"Wget/1.10.4", false, "Older minor version not allowed"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.userAgent, func(t *testing.T) {
+			result := isValidI2PUserAgent(tc.userAgent)
+			if result != tc.shouldAccept {
+				t.Errorf("For user agent %q: expected %v, got %v. %s",
+					tc.userAgent, tc.shouldAccept, result, tc.description)
+			}
+		})
+	}
+}