feature: accesslogger

internal/net/http/accesslog/fields.go

@@ -0,0 +1,103 @@
+package accesslog
+
+import (
+	"net/http"
+	"net/url"
+)
+
+type (
+	FieldConfig struct {
+		DefaultMode FieldMode            `validate:"oneof=keep drop redact"`
+		Config      map[string]FieldMode `validate:"dive,oneof=keep drop redact"`
+	}
+	FieldMode string
+)
+
+const (
+	FieldModeKeep   FieldMode = "keep"
+	FieldModeDrop   FieldMode = "drop"
+	FieldModeRedact FieldMode = "redact"
+
+	RedactedValue = "REDACTED"
+)
+
+func processMap[V any](cfg *FieldConfig, m map[string]V, redactedV V) map[string]V {
+	if len(cfg.Config) == 0 {
+		switch cfg.DefaultMode {
+		case FieldModeKeep:
+			return m
+		case FieldModeDrop:
+			return nil
+		case FieldModeRedact:
+			redacted := make(map[string]V)
+			for k := range m {
+				redacted[k] = redactedV
+			}
+			return redacted
+		}
+	}
+
+	if len(m) == 0 {
+		return m
+	}
+
+	newMap := make(map[string]V)
+	for k := range m {
+		var mode FieldMode
+		var ok bool
+		if mode, ok = cfg.Config[k]; !ok {
+			mode = cfg.DefaultMode
+		}
+		switch mode {
+		case FieldModeKeep:
+			newMap[k] = m[k]
+		case FieldModeRedact:
+			newMap[k] = redactedV
+		}
+	}
+	return newMap
+}
+
+func processSlice[V any, VReturn any](cfg *FieldConfig, s []V, getKey func(V) string, convert func(V) VReturn, redact func(V) VReturn) map[string]VReturn {
+	if len(s) == 0 ||
+		len(cfg.Config) == 0 && cfg.DefaultMode == FieldModeDrop {
+		return nil
+	}
+	newMap := make(map[string]VReturn, len(s))
+	for _, v := range s {
+		var mode FieldMode
+		var ok bool
+		k := getKey(v)
+		if mode, ok = cfg.Config[k]; !ok {
+			mode = cfg.DefaultMode
+		}
+		switch mode {
+		case FieldModeKeep:
+			newMap[k] = convert(v)
+		case FieldModeRedact:
+			newMap[k] = redact(v)
+		}
+	}
+	return newMap
+}
+
+func (cfg *FieldConfig) ProcessHeaders(headers http.Header) http.Header {
+	return processMap(cfg, headers, []string{RedactedValue})
+}
+
+func (cfg *FieldConfig) ProcessQuery(q url.Values) url.Values {
+	return processMap(cfg, q, []string{RedactedValue})
+}
+
+func (cfg *FieldConfig) ProcessCookies(cookies []*http.Cookie) map[string]string {
+	return processSlice(cfg, cookies,
+		func(c *http.Cookie) string {
+			return c.Name
+		},
+		func(c *http.Cookie) string {
+			return c.Value
+		},
+		func(c *http.Cookie) string {
+			return RedactedValue
+		})
+}