First commit

fallback_receive.go

@@ -0,0 +1,84 @@
+package proxyprotocol
+
+import (
+	"bufio"
+	"errors"
+)
+
+// StubHeaderParser always return nil Header
+type StubHeaderParser struct{}
+
+// NewStubHeaderParser construct StubHeaderParser
+func NewStubHeaderParser() StubHeaderParser {
+	return StubHeaderParser{}
+}
+
+// Parse always return nil, nil
+func (parser StubHeaderParser) Parse(*bufio.Reader) (*Header, error) {
+	return nil, nil
+}
+
+// FallbackHeaderParserBuilder build FallbackHeaderParser
+type FallbackHeaderParserBuilder []HeaderParserBuilder
+
+// NewFallbackHeaderParserBuilder construct FallbackHeaderParserBuilder
+func NewFallbackHeaderParserBuilder(
+	headerParserBuilders ...HeaderParserBuilder,
+) FallbackHeaderParserBuilder {
+	return FallbackHeaderParserBuilder(headerParserBuilders)
+}
+
+// Build FallbackHeaderParser from headerParserBuilders
+func (headerParserBuilders FallbackHeaderParserBuilder) Build(logger Logger) HeaderParser {
+	headerParsers := make([]HeaderParser, 0, len(headerParserBuilders))
+	for _, headerParserBuilder := range headerParserBuilders {
+		headerParser := headerParserBuilder.Build(logger)
+		headerParsers = append(headerParsers, headerParser)
+	}
+	return FallbackHeaderParser{
+		Logger:        logger,
+		HeaderParsers: headerParsers,
+	}
+}
+
+// ErrInvalidHeader returned by FallbackHeaderParser when all headerParsers return
+// ErrInvalidSignature
+var ErrInvalidHeader = errors.New("invalid header")
+
+// FallbackHeaderParser iterate over HeaderParser until parser not return nil error.
+type FallbackHeaderParser struct {
+	Logger        Logger
+	HeaderParsers []HeaderParser
+}
+
+// NewFallbackHeaderParser create new instance of FallbackHeaderParser
+func NewFallbackHeaderParser(logger Logger, headerParsers ...HeaderParser) FallbackHeaderParser {
+	return FallbackHeaderParser{
+		Logger:        logger,
+		HeaderParsers: headerParsers,
+	}
+}
+
+// Parse iterate over headerParsers call Parse().
+//
+// If any parser return not nil or not ErrInvalidSignature error, then return its error.
+//
+// If any parser return nil error, then return header.
+//
+// If all parsers return error ErrInvalidSignature, then return ErrInvalidHeader.
+func (parser FallbackHeaderParser) Parse(buf *bufio.Reader) (*Header, error) {
+	for _, headerParser := range parser.HeaderParsers {
+		header, err := headerParser.Parse(buf)
+		switch err {
+		case nil:
+			parser.Logger.Printf("Use header remote addr")
+			return header, nil
+		case ErrInvalidSignature:
+			continue
+		default:
+			parser.Logger.Printf("Parse header error: %s", err)
+			return nil, err
+		}
+	}
+	return nil, ErrInvalidHeader
+}