add docs

internal/app/client_info_test.go

@@ -0,0 +1,96 @@
+package app
+
+import (
+	"context"
+	"testing"
+
+	"google.golang.org/grpc/metadata"
+)
+
+func TestClientInfoFromContext(t *testing.T) {
+	tests := []struct {
+		name          string
+		md            metadata.MD
+		wantIP        string
+		wantUserAgent string
+	}{
+		{
+			name:          "нет метаданных",
+			wantIP:        "",
+			wantUserAgent: "",
+		},
+		{
+			name: "x-forwarded-for через gateway: берём последний элемент",
+			md: metadata.MD{
+				"x-forwarded-for":        []string{"203.0.113.1, 198.51.100.7"},
+				"grpcgateway-user-agent": []string{"Mozilla/5.0 (test)"},
+			},
+			wantIP:        "198.51.100.7",
+			wantUserAgent: "Mozilla/5.0 (test)",
+		},
+		{
+			name: "x-real-ip от доверенного прокси приоритетнее x-forwarded-for",
+			md: metadata.MD{
+				"x-real-ip":              []string{"192.0.2.10"},
+				"x-forwarded-for":        []string{"203.0.113.1, 10.0.0.1"},
+				"grpcgateway-user-agent": []string{"curl/8.0"},
+			},
+			wantIP:        "192.0.2.10",
+			wantUserAgent: "curl/8.0",
+		},
+		{
+			name: "x-real-ip пустой — фолбэк на x-forwarded-for",
+			md: metadata.MD{
+				"x-real-ip":       []string{" "},
+				"x-forwarded-for": []string{"203.0.113.5"},
+			},
+			wantIP: "203.0.113.5",
+		},
+		{
+			name: "user-agent для прямого gRPC-клиента",
+			md: metadata.MD{
+				"user-agent": []string{"grpc-go/1.60"},
+			},
+			wantUserAgent: "grpc-go/1.60",
+		},
+		{
+			name: "x-forwarded-for с пробелами после запятых",
+			md: metadata.MD{
+				"x-forwarded-for": []string{"203.0.113.1 ,  198.51.100.7 "},
+			},
+			wantIP: "198.51.100.7",
+		},
+		{
+			name: "невалидный x-real-ip — фолбэк на валидный x-forwarded-for",
+			md: metadata.MD{
+				"x-real-ip":       []string{"not-an-ip; drop me"},
+				"x-forwarded-for": []string{"203.0.113.1, 198.51.100.7"},
+			},
+			wantIP: "198.51.100.7",
+		},
+		{
+			name: "все источники невалидны — IP пустой (спуфинг)",
+			md: metadata.MD{
+				"x-real-ip":       []string{"not-an-ip; drop me"},
+				"x-forwarded-for": []string{"256.256.256.256"},
+			},
+			wantIP: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var ctx context.Context = context.Background()
+			if tt.md != nil {
+				ctx = metadata.NewIncomingContext(ctx, tt.md)
+			}
+			ip, userAgent := clientInfoFromContext(ctx)
+			if ip != tt.wantIP {
+				t.Errorf("ip = %q, want %q", ip, tt.wantIP)
+			}
+			if userAgent != tt.wantUserAgent {
+				t.Errorf("userAgent = %q, want %q", userAgent, tt.wantUserAgent)
+			}
+		})
+	}
+}