refactor: get rid of package expressions by moving the code into package expression

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/checker/expression/README.md

@@ -0,0 +1,3 @@
+# Expressions support
+
+The expressions support is based on ideas from [go-away](https://git.gammaspectra.live/git/go-away) but with different opinions about how things should be done.

lib/checker/expression/checker.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/TecharoHQ/anubis/internal"
 	"github.com/TecharoHQ/anubis/lib/checker/expression/environment"
-	"github.com/TecharoHQ/anubis/lib/policy/expressions"
 	"github.com/google/cel-go/cel"
 	"github.com/google/cel-go/common/types"
 )
@@ -72,15 +71,15 @@ func (cr *CELRequest) ResolveName(name string) (any, bool) {
 	case "path":
 		return cr.URL.Path, true
 	case "query":
-		return expressions.URLValues{Values: cr.URL.Query()}, true
+		return URLValues{Values: cr.URL.Query()}, true
 	case "headers":
-		return expressions.HTTPHeaders{Header: cr.Header}, true
+		return HTTPHeaders{Header: cr.Header}, true
 	case "load_1m":
-		return expressions.Load1(), true
+		return Load1(), true
 	case "load_5m":
-		return expressions.Load5(), true
+		return Load5(), true
 	case "load_15m":
-		return expressions.Load15(), true
+		return Load15(), true
 	default:
 		return nil, false
 	}

lib/checker/expression/http_headers.go

@@ -0,0 +1,75 @@
+package expression
+
+import (
+	"net/http"
+	"reflect"
+	"strings"
+
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/common/types/traits"
+)
+
+// HTTPHeaders is a type wrapper to expose HTTP headers into CEL programs.
+type HTTPHeaders struct {
+	http.Header
+}
+
+func (h HTTPHeaders) ConvertToNative(typeDesc reflect.Type) (any, error) {
+	return nil, ErrNotImplemented
+}
+
+func (h HTTPHeaders) ConvertToType(typeVal ref.Type) ref.Val {
+	switch typeVal {
+	case types.MapType:
+		return h
+	case types.TypeType:
+		return types.MapType
+	}
+
+	return types.NewErr("can't convert from %q to %q", types.MapType, typeVal)
+}
+
+func (h HTTPHeaders) Equal(other ref.Val) ref.Val {
+	return types.Bool(false) // We don't want to compare header maps
+}
+
+func (h HTTPHeaders) Type() ref.Type {
+	return types.MapType
+}
+
+func (h HTTPHeaders) Value() any { return h }
+
+func (h HTTPHeaders) Find(key ref.Val) (ref.Val, bool) {
+	k, ok := key.(types.String)
+	if !ok {
+		return nil, false
+	}
+
+	if _, ok := h.Header[string(k)]; !ok {
+		return nil, false
+	}
+
+	return types.String(strings.Join(h.Header.Values(string(k)), ",")), true
+}
+
+func (h HTTPHeaders) Contains(key ref.Val) ref.Val {
+	_, ok := h.Find(key)
+	return types.Bool(ok)
+}
+
+func (h HTTPHeaders) Get(key ref.Val) ref.Val {
+	result, ok := h.Find(key)
+	if !ok {
+		return types.ValOrErr(result, "no such key: %v", key)
+	}
+	return result
+}
+
+func (h HTTPHeaders) Iterator() traits.Iterator { panic("TODO(Xe): implement me") }
+
+func (h HTTPHeaders) IsZeroValue() bool {
+	return len(h.Header) == 0
+}
+
+func (h HTTPHeaders) Size() ref.Val { return types.Int(len(h.Header)) }

lib/checker/expression/http_headers_test.go

@@ -0,0 +1,52 @@
+package expression
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/google/cel-go/common/types"
+)
+
+func TestHTTPHeaders(t *testing.T) {
+	headers := HTTPHeaders{
+		Header: http.Header{
+			"Content-Type": {"application/json"},
+			"Cf-Worker":    {"true"},
+			"User-Agent":   {"Go-http-client/2"},
+		},
+	}
+
+	t.Run("contains-existing-header", func(t *testing.T) {
+		resp := headers.Contains(types.String("User-Agent"))
+		if !resp.(types.Bool) {
+			t.Fatal("headers does not contain User-Agent")
+		}
+	})
+
+	t.Run("not-contains-missing-header", func(t *testing.T) {
+		resp := headers.Contains(types.String("Xxx-Random-Header"))
+		if resp.(types.Bool) {
+			t.Fatal("headers does not contain User-Agent")
+		}
+	})
+
+	t.Run("get-existing-header", func(t *testing.T) {
+		val := headers.Get(types.String("User-Agent"))
+		switch val.(type) {
+		case types.String:
+			// ok
+		default:
+			t.Fatalf("result was wrong type %T", val)
+		}
+	})
+
+	t.Run("not-get-missing-header", func(t *testing.T) {
+		val := headers.Get(types.String("Xxx-Random-Header"))
+		switch val.(type) {
+		case *types.Err:
+			// ok
+		default:
+			t.Fatalf("result was wrong type %T", val)
+		}
+	})
+}

lib/checker/expression/loadavg.go

@@ -0,0 +1,69 @@
+package expression
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+	"time"
+
+	"github.com/shirou/gopsutil/v4/load"
+)
+
+type loadAvg struct {
+	lock sync.RWMutex
+	data *load.AvgStat
+}
+
+func (l *loadAvg) updateThread(ctx context.Context) {
+	ticker := time.NewTicker(15 * time.Second)
+	defer ticker.Stop()
+
+	l.update()
+
+	for {
+		select {
+		case <-ticker.C:
+			l.update()
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (l *loadAvg) update() {
+	l.lock.Lock()
+	defer l.lock.Unlock()
+
+	var err error
+	l.data, err = load.Avg()
+	if err != nil {
+		slog.Debug("can't get load average", "err", err)
+	}
+}
+
+var (
+	globalLoadAvg *loadAvg
+)
+
+func init() {
+	globalLoadAvg = &loadAvg{}
+	go globalLoadAvg.updateThread(context.Background())
+}
+
+func Load1() float64 {
+	globalLoadAvg.lock.RLock()
+	defer globalLoadAvg.lock.RUnlock()
+	return globalLoadAvg.data.Load1
+}
+
+func Load5() float64 {
+	globalLoadAvg.lock.RLock()
+	defer globalLoadAvg.lock.RUnlock()
+	return globalLoadAvg.data.Load5
+}
+
+func Load15() float64 {
+	globalLoadAvg.lock.RLock()
+	defer globalLoadAvg.lock.RUnlock()
+	return globalLoadAvg.data.Load15
+}

lib/checker/expression/url_values.go

@@ -0,0 +1,78 @@
+package expression
+
+import (
+	"errors"
+	"net/url"
+	"reflect"
+	"strings"
+
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/common/types/traits"
+)
+
+var ErrNotImplemented = errors.New("expressions: not implemented")
+
+// URLValues is a type wrapper to expose url.Values into CEL programs.
+type URLValues struct {
+	url.Values
+}
+
+func (u URLValues) ConvertToNative(typeDesc reflect.Type) (any, error) {
+	return nil, ErrNotImplemented
+}
+
+func (u URLValues) ConvertToType(typeVal ref.Type) ref.Val {
+	switch typeVal {
+	case types.MapType:
+		return u
+	case types.TypeType:
+		return types.MapType
+	}
+
+	return types.NewErr("can't convert from %q to %q", types.MapType, typeVal)
+}
+
+func (u URLValues) Equal(other ref.Val) ref.Val {
+	return types.Bool(false) // We don't want to compare header maps
+}
+
+func (u URLValues) Type() ref.Type {
+	return types.MapType
+}
+
+func (u URLValues) Value() any { return u }
+
+func (u URLValues) Find(key ref.Val) (ref.Val, bool) {
+	k, ok := key.(types.String)
+	if !ok {
+		return nil, false
+	}
+
+	if _, ok := u.Values[string(k)]; !ok {
+		return nil, false
+	}
+
+	return types.String(strings.Join(u.Values[string(k)], ",")), true
+}
+
+func (u URLValues) Contains(key ref.Val) ref.Val {
+	_, ok := u.Find(key)
+	return types.Bool(ok)
+}
+
+func (u URLValues) Get(key ref.Val) ref.Val {
+	result, ok := u.Find(key)
+	if !ok {
+		return types.ValOrErr(result, "no such key: %v", key)
+	}
+	return result
+}
+
+func (u URLValues) Iterator() traits.Iterator { panic("TODO(Xe): implement me") }
+
+func (u URLValues) IsZeroValue() bool {
+	return len(u.Values) == 0
+}
+
+func (u URLValues) Size() ref.Val { return types.Int(len(u.Values)) }

lib/checker/expression/url_values_test.go

@@ -0,0 +1,50 @@
+package expression
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/google/cel-go/common/types"
+)
+
+func TestURLValues(t *testing.T) {
+	headers := URLValues{
+		Values: url.Values{
+			"format": {"json"},
+		},
+	}
+
+	t.Run("contains-existing-key", func(t *testing.T) {
+		resp := headers.Contains(types.String("format"))
+		if !resp.(types.Bool) {
+			t.Fatal("headers does not contain User-Agent")
+		}
+	})
+
+	t.Run("not-contains-missing-key", func(t *testing.T) {
+		resp := headers.Contains(types.String("not-there"))
+		if resp.(types.Bool) {
+			t.Fatal("headers does not contain User-Agent")
+		}
+	})
+
+	t.Run("get-existing-key", func(t *testing.T) {
+		val := headers.Get(types.String("format"))
+		switch val.(type) {
+		case types.String:
+			// ok
+		default:
+			t.Fatalf("result was wrong type %T", val)
+		}
+	})
+
+	t.Run("not-get-missing-key", func(t *testing.T) {
+		val := headers.Get(types.String("not-there"))
+		switch val.(type) {
+		case *types.Err:
+			// ok
+		default:
+			t.Fatalf("result was wrong type %T", val)
+		}
+	})
+}