writer.go

//
// Copyright © 2011-2018 Guy M. Allard
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

package stompngo

import (
	"bufio"
	"bytes"
	"net"

	// "bytes"
	"strconv"
	"time"
)

/*
	Write data to logical network writer.  Writer will take care of the output wire data.
	If the underlying connection goes bad and writer give up working, the closed ssdc chan
	will make sure write action aware that happens.
*/
func (c *Connection) writeWireData(wd wiredata) error {
	select {
	case c.output <- wd:
	case <-c.ssdc:
		return ECONBAD
	}
	return nil
}

/*
	Logical network writer.  Read wiredata structures from the communication
	channel, and put the frame on the wire.
*/
func (c *Connection) writer() {
writerLoop:
	for {
		select {
		case d := <-c.output:
			c.log("WTR_WIREWRITE start")
			c.wireWrite(d)
			logLock.Lock()
			if c.logger != nil {
				c.logx("WTR_WIREWRITE COMPLETE", d.frame.Command, d.frame.Headers,
					HexData(d.frame.Body))
			}
			logLock.Unlock()
			if d.frame.Command == DISCONNECT {
				break writerLoop // we are done with this connection
			}
		case _ = <-c.ssdc:
			c.log("WTR_WIREWRITE shutdown S received")
			break writerLoop
		case _ = <-c.wtrsdc:
			c.log("WTR_WIREWRITE shutdown W received")
			break writerLoop
		}
	} // of for
	//
	c.connLock.Lock()
	c.connected = false
	c.connLock.Unlock()
	c.sysAbort()
	c.log("WTR_SHUTDOWN", time.Now())
}

/*
	Connection logical write.
*/
func (c *Connection) wireWrite(d wiredata) {
	f := &d.frame
	// fmt.Printf("WWD01 f:[%v]\n", f)
	switch f.Command {
	case "\n": // HeartBeat frame
		if c.dld.wde && c.dld.wds {
			_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
		}
		_, e := c.wtr.WriteString(f.Command)
		if e != nil {
			if e.(net.Error).Timeout() {
				if c.dld.dns {
					c.dld.dlnotify(e, true)
				}
			}
			d.errchan <- e
			return
		}
	default: // Other frames
		if e := f.writeFrame(c.wtr, c); e != nil {
			d.errchan <- e
			return
		}
		if e := c.wtr.Flush(); e != nil {
			d.errchan <- e
			return
		}
	}
	if e := c.wtr.Flush(); e != nil {
		d.errchan <- e
		return
	}
	//
	if c.hbd != nil {
		c.hbd.sdl.Lock()
		c.hbd.ls = time.Now().UnixNano() // Latest good send
		c.hbd.sdl.Unlock()
	}
	c.mets.tfw++                // Frame written count
	c.mets.tbw += f.Size(false) // Bytes written count
	//
	d.errchan <- nil
	return
}

/*
	Physical frame write to the wire.
*/
func (f *Frame) writeFrame(w *bufio.Writer, c *Connection) error {

	var sctok bool
	// Content type.  Always add it if the client does not suppress and does not
	// supply it.
	_, sctok = f.Headers.Contains(HK_SUPPRESS_CT)
	if !sctok {
		if _, ctok := f.Headers.Contains(HK_CONTENT_TYPE); !ctok {
			f.Headers = append(f.Headers, HK_CONTENT_TYPE,
				DFLT_CONTENT_TYPE)
		}
	}

	var sclok bool
	// Content length - Always add it if client does not suppress it and
	// does not supply it.
	_, sclok = f.Headers.Contains(HK_SUPPRESS_CL)
	if !sclok {
		if _, clok := f.Headers.Contains(HK_CONTENT_LENGTH); !clok {
			f.Headers = append(f.Headers, HK_CONTENT_LENGTH, strconv.Itoa(len(f.Body)))
		}
	}
	// Encode the headers if needed
	if c.Protocol() > SPL_10 && f.Command != CONNECT {
		for i := 0; i < len(f.Headers); i += 2 {
			f.Headers[i] = encode(f.Headers[i])
			f.Headers[i+1] = encode(f.Headers[i+1])
		}
	}

	if sclok {
		nz := bytes.IndexByte(f.Body, 0)
		// fmt.Printf("WDBG41 ok:%v\n", nz)
		if nz == 0 {
			f.Body = []byte{}
			// fmt.Printf("WDBG42 body:%v bodystring: %v\n", f.Body, string(f.Body))
		} else if nz > 0 {
			f.Body = f.Body[0:nz]
			// fmt.Printf("WDBG43 body:%v bodystring: %v\n", f.Body, string(f.Body))
		}
	}

	if c.dld.wde && c.dld.wds {
		_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
	}

	// Writes start

	// Write the frame Command
	_, e := w.WriteString(f.Command + "\n")
	if c.checkWriteError(e) != nil {
		return e
	}
	// fmt.Println("WRCMD", f.Command)
	// Write the frame Headers
	for i := 0; i < len(f.Headers); i += 2 {
		if c.dld.wde && c.dld.wds {
			_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
		}
		_, e := w.WriteString(f.Headers[i] + ":" + f.Headers[i+1] + "\n")
		if c.checkWriteError(e) != nil {
			return e
		}
		// fmt.Println("WRHDR", f.Headers[i]+":"+f.Headers[i+1]+"\n")
	}

	// Write the last Header LF
	if c.dld.wde && c.dld.wds {
		_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
	}
	e = w.WriteByte('\n')
	if c.checkWriteError(e) != nil {
		return e
	}
	// fmt.Printf("WDBG40 ok:%v\n", sclok)

	// Write the body
	if len(f.Body) != 0 { // Foolish to write 0 length data
		// fmt.Println("WRBDY", f.Body)
		e := c.writeBody(f)
		if c.checkWriteError(e) != nil {
			return e
		}
	}
	if c.dld.wde && c.dld.wds {
		_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
	}
	e = w.WriteByte(0)
	if c.checkWriteError(e) != nil {
		return e
	}
	// End of write loop - set no deadline
	if c.dld.wde {
		_ = c.netconn.SetWriteDeadline(c.dld.t0)
	}
	return nil
}

func (c *Connection) checkWriteError(e error) error {
	if e == nil {
		return e
	}
	ne, ok := e.(net.Error)
	if !ok {
		return e
	}
	if ne.Timeout() {
		if c.dld.dns {
			c.log("invoking write deadline callback 1")
			c.dld.dlnotify(e, true)
		}
	}
	return e
}

func (c *Connection) writeBody(f *Frame) error {
	// fmt.Printf("WDBG99 body:%v bodystring: %v\n", f.Body, string(f.Body))
	var n = 0
	var e error
	for {
		if c.dld.wde && c.dld.wds {
			_ = c.netconn.SetWriteDeadline(time.Now().Add(c.dld.wdld))
		}
		n, e = c.wtr.Write(f.Body)
		if n == len(f.Body) {
			return e
		}
		c.log("SHORT WRITE", n, len(f.Body))
		if n == 0 { // Zero bytes would mean something is seriously wrong.
			return e
		}
		if !c.dld.rfsw {
			return e
		}
		if c.dld.wde && c.dld.wds && c.dld.dns && isErrorTimeout(e) {
			c.log("invoking write deadline callback 2")
			c.dld.dlnotify(e, true)
		}
		// *Any* error from a bufio.Writer is *not* recoverable.  See code in
		// bufio.go to understand this.  We get a new writer here, to clear any
		// error condition.
		c.wtr = bufio.NewWriter(c.netconn) // Create new writer
		f.Body = f.Body[n:]
	}
}

func isErrorTimeout(e error) bool {
	if e == nil {
		return false
	}
	_, ok := e.(net.Error)
	if !ok {
		return false
	}
	return true
}