Initial commit

application/command/header.go

@@ -0,0 +1,143 @@
+// Sshwifty - A Web SSH client
+//
+// Copyright (C) 2019 Rui NI <nirui@gmx.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package command
+
+import "fmt"
+
+// Header Packet Type
+type Header byte
+
+// Packet Types
+const (
+	// 00------: Control signals
+	// Remaing bits: Data length
+	//
+	// Format:
+	//   0011111 [63 bytes long data] - 63 bytes of control data
+	//
+	HeaderControl Header = 0x00
+
+	// 01------: Bidirectional stream data
+	// Remaining bits: Stream ID
+	// Followed by: Parameter or data
+	//
+	// Format:
+	//   0111111 [Command parameters / data] - Open/use stream 63 to execute
+	//                                         command or transmit data
+	HeaderStream Header = 0x40
+
+	// 10------: Close stream
+	// Remaining bits: Stream ID
+	//
+	// Format:
+	//   1011111 - Close stream 63
+	//
+	// WARNING: The requester MUST NOT send any data to this stream once this
+	//          header is sent.
+	//
+	// WARNING: The receiver MUST reply with a Completed header to indicate
+	//          the success of the Close action. Until a Completed header is
+	//          replied, all data from the sender must be proccessed as normal.
+	HeaderClose Header = 0x80
+
+	// 11------: Stream has been closed/completed in respond to client request
+	// Remaining bits: Stream ID
+	//
+	// Format:
+	//   1111111 - Stream 63 is completed
+	//
+	// WARNING: This header can ONLY be send in respond to a Close header
+	//
+	// WARNING: The sender of this header MUST NOT send any data to the stream
+	//          once this header is sent until this stream been re-opened by a
+	//          Data header
+	HeaderCompleted Header = 0xc0
+)
+
+// Control signal types
+const (
+	HeaderControlEcho         = 0x00
+	HeaderControlPauseStream  = 0x01
+	HeaderControlResumeStream = 0x02
+)
+
+// Consts
+const (
+	HeaderMaxData = 0x3f
+)
+
+// Cutters
+const (
+	headerHeaderCutter = 0xc0
+	headerDataCutter   = 0x3f
+)
+
+// Type get packet type
+func (p Header) Type() Header {
+	return (p & headerHeaderCutter)
+}
+
+// Data returns the data of current Packet header
+func (p Header) Data() byte {
+	return byte(p & headerDataCutter)
+}
+
+// Set set a new value of the Header
+func (p *Header) Set(data byte) {
+	if data > headerDataCutter {
+		panic("data must not be greater than 0x3f")
+	}
+
+	*p |= (headerDataCutter & Header(data))
+}
+
+// Set set a new value of the Header
+func (p Header) String() string {
+	switch p.Type() {
+	case HeaderControl:
+		return fmt.Sprintf("Control (%d bytes)", p.Data())
+
+	case HeaderStream:
+		return fmt.Sprintf("Stream (%d)", p.Data())
+
+	case HeaderClose:
+		return fmt.Sprintf("Close (Stream %d)", p.Data())
+
+	case HeaderCompleted:
+		return fmt.Sprintf("Completed (Stream %d)", p.Data())
+
+	default:
+		return "Unknown"
+	}
+}
+
+// IsStreamControl returns true when the header is for stream control, false
+// when otherwise
+func (p Header) IsStreamControl() bool {
+	switch p {
+	case HeaderStream:
+		fallthrough
+	case HeaderClose:
+		fallthrough
+	case HeaderCompleted:
+		return true
+
+	default:
+		return false
+	}
+}