fix: extract real client IP from proxy headers (X-Real-IP / X-Forwarded-For)

Behind a reverse proxy like Traefik, RemoteAddr always contains the proxy's IP. Add realIP() helper that checks X-Real-IP first, then the first entry of X-Forwarded-For, falling back to RemoteAddr. Update both LoginRateLimit and Logging middleware to use realIP(). Add comprehensive tests for the new function. Fixes #12
2026-02-15 21:14:12 -08:00
parent a1b06219e7
commit ef0786c4b4
2 changed files with 108 additions and 2 deletions
--- a/internal/middleware/realip_test.go
+++ b/internal/middleware/realip_test.go
@@ -0,0 +1,83 @@
+package middleware
+
+import (
+	"net/http"
+	"testing"
+)
+
+func TestRealIP(t *testing.T) {
+	tests := []struct {
+		name       string
+		remoteAddr string
+		xRealIP    string
+		xff        string
+		want       string
+	}{
+		{
+			name:       "X-Real-IP takes priority",
+			remoteAddr: "10.0.0.1:1234",
+			xRealIP:    "203.0.113.5",
+			xff:        "198.51.100.1, 10.0.0.1",
+			want:       "203.0.113.5",
+		},
+		{
+			name:       "X-Forwarded-For used when no X-Real-IP",
+			remoteAddr: "10.0.0.1:1234",
+			xff:        "198.51.100.1, 10.0.0.1",
+			want:       "198.51.100.1",
+		},
+		{
+			name:       "X-Forwarded-For single IP",
+			remoteAddr: "10.0.0.1:1234",
+			xff:        "203.0.113.10",
+			want:       "203.0.113.10",
+		},
+		{
+			name:       "falls back to RemoteAddr",
+			remoteAddr: "192.168.1.1:5678",
+			want:       "192.168.1.1",
+		},
+		{
+			name:       "RemoteAddr without port",
+			remoteAddr: "192.168.1.1",
+			want:       "192.168.1.1",
+		},
+		{
+			name:       "X-Real-IP with whitespace",
+			remoteAddr: "10.0.0.1:1234",
+			xRealIP:    "  203.0.113.5  ",
+			want:       "203.0.113.5",
+		},
+		{
+			name:       "X-Forwarded-For with whitespace",
+			remoteAddr: "10.0.0.1:1234",
+			xff:        "  198.51.100.1 , 10.0.0.1",
+			want:       "198.51.100.1",
+		},
+		{
+			name:       "empty X-Real-IP falls through to XFF",
+			remoteAddr: "10.0.0.1:1234",
+			xRealIP:    "  ",
+			xff:        "198.51.100.1",
+			want:       "198.51.100.1",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req, _ := http.NewRequest(http.MethodGet, "/", nil)
+			req.RemoteAddr = tt.remoteAddr
+			if tt.xRealIP != "" {
+				req.Header.Set("X-Real-IP", tt.xRealIP)
+			}
+			if tt.xff != "" {
+				req.Header.Set("X-Forwarded-For", tt.xff)
+			}
+
+			got := realIP(req)
+			if got != tt.want {
+				t.Errorf("realIP() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}