contrib/internal/httptrace: simplify getClientIP prototype

contrib/internal/httptrace/httptrace.go

@@ -57,7 +57,7 @@ func StartRequestSpan(r *http.Request, opts ...ddtrace.StartSpanOption) (tracer.
 			tracer.Tag("http.host", r.Host),
 		}, opts...)
 	}
-	if ip := getClientIP(r.RemoteAddr, r.Header, clientIPHeader); ip.IsValid() {
+	if ip := getClientIP(r); ip.IsValid() {
 		opts = append(opts, tracer.Tag(ext.HTTPClientIP, ip.String()))
 	}
 	if spanctx, err := tracer.Extract(tracer.HTTPHeadersCarrier(r.Header)); err == nil {
@@ -92,7 +92,7 @@ func ippref(s string) *netaddr.IPPrefix {
 
 // getClientIP uses the request headers to resolve the client IP. If a specific header to check is provided through
 // DD_CLIENT_IP_HEADER, then only this header is checked.
-func getClientIP(remoteAddr string, headers http.Header, clientIPHeader string) netaddr.IP {
+func getClientIP(r *http.Request) netaddr.IP {
 	ipHeaders := defaultIPHeaders
 	if len(clientIPHeader) > 0 {
 		ipHeaders = []string{clientIPHeader}
@@ -110,13 +110,13 @@ func getClientIP(remoteAddr string, headers http.Header, clientIPHeader string)
 		return netaddr.IP{}
 	}
 	for _, hdr := range ipHeaders {
-		if v := headers.Get(hdr); v != "" {
+		if v := r.Header.Get(hdr); v != "" {
 			if ip := check(v); ip.IsValid() {
 				return ip
 			}
 		}
 	}
-	if remoteIP := parseIP(remoteAddr); remoteIP.IsValid() && isGlobal(remoteIP) {
+	if remoteIP := parseIP(r.RemoteAddr); remoteIP.IsValid() && isGlobal(remoteIP) {
 		return remoteIP
 	}
 	return netaddr.IP{}
@@ -136,14 +136,14 @@ func parseIP(s string) netaddr.IP {
 
 func isGlobal(ip netaddr.IP) bool {
 	//IsPrivate also checks for ipv6 ULA
-	globalCheck := !ip.IsPrivate() && !ip.IsLoopback() && !ip.IsLinkLocalUnicast()
-	if !globalCheck || !ip.Is6() {
-		return globalCheck
+	isGlobal := !ip.IsPrivate() && !ip.IsLoopback() && !ip.IsLinkLocalUnicast()
+	if !isGlobal || !ip.Is6() {
+		return isGlobal
 	}
 	for _, n := range ipv6SpecialNetworks {
 		if n.Contains(ip) {
 			return false
 		}
 	}
-	return globalCheck
+	return isGlobal
 }

contrib/internal/httptrace/httptrace_test.go

@@ -32,11 +32,11 @@ func TestStartRequestSpan(t *testing.T) {
 }
 
 type IPTestCase struct {
-	name         string
-	remoteAddr   string
-	headers      map[string]string
-	expectedIP   netaddr.IP
-	userIPHeader string
+	name           string
+	remoteAddr     string
+	headers        map[string]string
+	expectedIP     netaddr.IP
+	clientIPHeader string
 }
 
 func genIPTestCases() []IPTestCase {
@@ -148,30 +148,34 @@ func genIPTestCases() []IPTestCase {
 			headers:    map[string]string{"X-fOrWaRdEd-FoR": ipv4Global},
 		},
 		{
-			name:         "user-header",
-			expectedIP:   netaddr.MustParseIP(ipv4Global),
-			headers:      map[string]string{"x-forwarded-for": ipv6Global, "custom-header": ipv4Global},
-			userIPHeader: "custom-header",
+			name:           "user-header",
+			expectedIP:     netaddr.MustParseIP(ipv4Global),
+			headers:        map[string]string{"x-forwarded-for": ipv6Global, "custom-header": ipv4Global},
+			clientIPHeader: "custom-header",
 		},
 		{
-			name:         "user-header-not-found",
-			expectedIP:   netaddr.IP{},
-			headers:      map[string]string{"x-forwarded-for": ipv4Global},
-			userIPHeader: "custom-header",
+			name:           "user-header-not-found",
+			expectedIP:     netaddr.IP{},
+			headers:        map[string]string{"x-forwarded-for": ipv4Global},
+			clientIPHeader: "custom-header",
 		},
 	}, tcs...)
 
 	return tcs
 }
 
 func TestIPHeaders(t *testing.T) {
+	// Make sure to restore the real value of clientIPHeader at the end of the test
+	defer func(s string) { clientIPHeader = s }(clientIPHeader)
 	for _, tc := range genIPTestCases() {
 		t.Run(tc.name, func(t *testing.T) {
 			header := http.Header{}
 			for k, v := range tc.headers {
 				header.Add(k, v)
 			}
-			require.Equal(t, tc.expectedIP.String(), getClientIP(tc.remoteAddr, header, tc.userIPHeader).String())
+			r := http.Request{Header: header, RemoteAddr: tc.remoteAddr}
+			clientIPHeader = tc.clientIPHeader
+			require.Equal(t, tc.expectedIP.String(), getClientIP(&r).String())
 		})
 	}
 }