feat: WIP ACL

extras/outbounds/acl/parse.go

@@ -0,0 +1,79 @@
+package acl
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+)
+
+var linePattern = regexp.MustCompile(`^(\w+)\s*\(([^,]+)(?:,([^,]+))?(?:,([^,]+))?\)$`)
+
+type InvalidSyntaxError struct {
+	Line    string
+	LineNum int
+}
+
+func (e *InvalidSyntaxError) Error() string {
+	return fmt.Sprintf("invalid syntax at line %d: %s", e.LineNum, e.Line)
+}
+
+// TextRule is the struct representation of a (non-comment) line parsed from an ACL file.
+// A line can be parsed into a TextRule as long as it matches one of the following patterns:
+//
+//	outbound(address)
+//	outbound(address,protoPort)
+//	outbound(address,protoPort,hijackAddress)
+//
+// It does not check whether any of the fields is valid - it's up to the compiler to do so.
+type TextRule struct {
+	Outbound      string
+	Address       string
+	ProtoPort     string
+	HijackAddress string
+}
+
+func parseLine(line string) *TextRule {
+	matches := linePattern.FindStringSubmatch(line)
+	if matches == nil {
+		return nil
+	}
+	return &TextRule{
+		Outbound:      matches[1],
+		Address:       strings.TrimSpace(matches[2]),
+		ProtoPort:     strings.TrimSpace(matches[3]),
+		HijackAddress: strings.TrimSpace(matches[4]),
+	}
+}
+
+func ParseTextRules(text string) ([]TextRule, error) {
+	rules := make([]TextRule, 0)
+	lineNum := 0
+	for _, line := range strings.Split(text, "\n") {
+		lineNum++
+		// Remove comments
+		if i := strings.Index(line, "#"); i >= 0 {
+			line = line[:i]
+		}
+		line = strings.TrimSpace(line)
+		// Skip empty lines
+		if len(line) == 0 {
+			continue
+		}
+		// Parse line
+		rule := parseLine(line)
+		if rule == nil {
+			return nil, &InvalidSyntaxError{line, lineNum}
+		}
+		rules = append(rules, *rule)
+	}
+	return rules, nil
+}
+
+func ParseTextRulesFile(filename string) ([]TextRule, error) {
+	bs, err := os.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	return ParseTextRules(string(bs))
+}