refactor: prepare trusted proxies

context_test.go

@@ -1440,7 +1440,6 @@ func TestContextAbortWithError(t *testing.T) {
 func TestContextClientIP(t *testing.T) {
 	c, _ := CreateTestContext(httptest.NewRecorder())
 	c.Request, _ = http.NewRequest("POST", "/", nil)
-	c.engine.trustedCIDRs, _ = c.engine.prepareTrustedCIDRs()
 	resetContextForClientIPTests(c)
 
 	// Legacy tests (validating that the defaults don't break the

gin.go

@@ -387,33 +387,22 @@ func (engine *Engine) Run(addr ...string) (err error) {
 	return
 }
 
-func (engine *Engine) prepareTrustedCIDRs() ([]*net.IPNet, error) {
-	if engine.trustedProxies == nil {
+func prepareTrustedCIDRs(trustedProxies []string) ([]*net.IPNet, error) {
+	if trustedProxies == nil {
 		return nil, nil
 	}
 
-	cidr := make([]*net.IPNet, 0, len(engine.trustedProxies))
-	for _, trustedProxy := range engine.trustedProxies {
-		if !strings.Contains(trustedProxy, "/") {
-			ip := parseIP(trustedProxy)
-			if ip == nil {
-				return cidr, &net.ParseError{Type: "IP address", Text: trustedProxy}
-			}
+	cidrArr := make([]*net.IPNet, 0, len(trustedProxies))
 
-			switch len(ip) {
-			case net.IPv4len:
-				trustedProxy += "/32"
-			case net.IPv6len:
-				trustedProxy += "/128"
-			}
-		}
-		_, cidrNet, err := net.ParseCIDR(trustedProxy)
+	for _, trustedProxy := range trustedProxies {
+        cidrNet, err := prepareCIDR(trustedProxy)
 		if err != nil {
-			return cidr, err
+			return cidrArr, err
 		}
-		cidr = append(cidr, cidrNet)
+		cidrArr = append(cidrArr, cidrNet)
 	}
-	return cidr, nil
+
+	return cidrArr, nil
 }
 
 // SetTrustedProxies set a list of network origins (IPv4 addresses,
@@ -426,7 +415,35 @@ func (engine *Engine) prepareTrustedCIDRs() ([]*net.IPNet, error) {
 // return the remote address directly.
 func (engine *Engine) SetTrustedProxies(trustedProxies []string) error {
 	engine.trustedProxies = trustedProxies
-	return engine.parseTrustedProxies()
+	trustedCIDRs, err := prepareTrustedCIDRs(trustedProxies)
+	engine.trustedCIDRs = trustedCIDRs
+	return err
+}
+
+// converts a string CIDR or single IP to a IPNet instance
+func prepareCIDR(ipOrCidr string) (*net.IPNet, error) {
+    // not a CIDR, try to convert to cidr notation
+    if !strings.Contains(ipOrCidr, "/") {
+        ip := parseIP(ipOrCidr)
+        if ip == nil {
+            return nil, &net.ParseError{Type: "IP address", Text: ipOrCidr}
+        }
+
+        switch len(ip) {
+        case net.IPv4len:
+            ipOrCidr += "/32"
+        case net.IPv6len:
+            ipOrCidr += "/128"
+        }
+    }
+
+    _, cidrNet, err := net.ParseCIDR(ipOrCidr)
+
+    if err != nil {
+        return nil, err
+    }
+
+    return cidrNet, err
 }
 
 // isUnsafeTrustedProxies checks if Engine.trustedCIDRs contains all IPs, it's not safe if it has (returns true)
@@ -434,13 +451,6 @@ func (engine *Engine) isUnsafeTrustedProxies() bool {
 	return engine.isTrustedProxy(net.ParseIP("0.0.0.0")) || engine.isTrustedProxy(net.ParseIP("::"))
 }
 
-// parseTrustedProxies parse Engine.trustedProxies to Engine.trustedCIDRs
-func (engine *Engine) parseTrustedProxies() error {
-	trustedCIDRs, err := engine.prepareTrustedCIDRs()
-	engine.trustedCIDRs = trustedCIDRs
-	return err
-}
-
 // isTrustedProxy will check whether the IP address is included in the trusted list according to Engine.trustedCIDRs
 func (engine *Engine) isTrustedProxy(ip net.IP) bool {
 	if engine.trustedCIDRs == nil {

logger_test.go

@@ -183,10 +183,7 @@ func TestLoggerWithConfigFormatting(t *testing.T) {
 	var gotParam LogFormatterParams
 	var gotKeys map[string]any
 	buffer := new(strings.Builder)
-
 	router := New()
-	router.engine.trustedCIDRs, _ = router.engine.prepareTrustedCIDRs()
-
 	router.Use(LoggerWithConfig(LoggerConfig{
 		Output: buffer,
 		Formatter: func(param LogFormatterParams) string {