feature: added nsq as broker for events (#6740)

vendor/github.com/nsqio/go-nsq/protocol.go

@@ -0,0 +1,96 @@
+package nsq
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+	"regexp"
+)
+
+// MagicV1 is the initial identifier sent when connecting for V1 clients
+var MagicV1 = []byte("  V1")
+
+// MagicV2 is the initial identifier sent when connecting for V2 clients
+var MagicV2 = []byte("  V2")
+
+// frame types
+const (
+	FrameTypeResponse int32 = 0
+	FrameTypeError    int32 = 1
+	FrameTypeMessage  int32 = 2
+)
+
+var validTopicChannelNameRegex = regexp.MustCompile(`^[\.a-zA-Z0-9_-]+(#ephemeral)?$`)
+
+// IsValidTopicName checks a topic name for correctness
+func IsValidTopicName(name string) bool {
+	return isValidName(name)
+}
+
+// IsValidChannelName checks a channel name for correctness
+func IsValidChannelName(name string) bool {
+	return isValidName(name)
+}
+
+func isValidName(name string) bool {
+	if len(name) > 64 || len(name) < 1 {
+		return false
+	}
+	return validTopicChannelNameRegex.MatchString(name)
+}
+
+// ReadResponse is a client-side utility function to read from the supplied Reader
+// according to the NSQ protocol spec:
+//
+//    [x][x][x][x][x][x][x][x]...
+//    |  (int32) || (binary)
+//    |  4-byte  || N-byte
+//    ------------------------...
+//        size       data
+func ReadResponse(r io.Reader) ([]byte, error) {
+	var msgSize int32
+
+	// message size
+	err := binary.Read(r, binary.BigEndian, &msgSize)
+	if err != nil {
+		return nil, err
+	}
+
+	// message binary data
+	buf := make([]byte, msgSize)
+	_, err = io.ReadFull(r, buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf, nil
+}
+
+// UnpackResponse is a client-side utility function that unpacks serialized data
+// according to NSQ protocol spec:
+//
+//    [x][x][x][x][x][x][x][x]...
+//    |  (int32) || (binary)
+//    |  4-byte  || N-byte
+//    ------------------------...
+//      frame ID     data
+//
+// Returns a triplicate of: frame type, data ([]byte), error
+func UnpackResponse(response []byte) (int32, []byte, error) {
+	if len(response) < 4 {
+		return -1, nil, errors.New("length of response is too small")
+	}
+
+	return int32(binary.BigEndian.Uint32(response)), response[4:], nil
+}
+
+// ReadUnpackedResponse reads and parses data from the underlying
+// TCP connection according to the NSQ TCP protocol spec and
+// returns the frameType, data or error
+func ReadUnpackedResponse(r io.Reader) (int32, []byte, error) {
+	resp, err := ReadResponse(r)
+	if err != nil {
+		return -1, nil, err
+	}
+	return UnpackResponse(resp)
+}