tcp.go

// Copyright 2017 Inca Roads LLC.  All rights reserved.
// Use of this source code is governed by licenses granted by the
// copyright holder including that found in the LICENSE file.

// Inbound TCP support
package main

import (
	"bufio"
	"fmt"
	"io"
	"net"
)

// TCPInboundHandler kicks off TCP single-upload request server
func TCPInboundHandler() {

	fmt.Printf("Now handling inbound TCP on %s%s\n", ThisServerAddressIPv4, TTServerTCPPort)

	ServerAddr, err := net.ResolveTCPAddr("tcp", TTServerTCPPort)
	if err != nil {
		fmt.Printf("Error resolving TCP port: \n%v\n", err)
		return
	}

	ServerConn, err := net.ListenTCP("tcp", ServerAddr)
	if err != nil {
		fmt.Printf("Error listening on TCP port: \n%v\n", err)
		return
	}
	defer ServerConn.Close()

	for {

		// Accept the TCP connection
		conn, err := ServerConn.AcceptTCP()
		if err != nil {
			fmt.Printf("\nTCP: rror accepting TCP session: \n%v\n", err)
			continue
		}

		// Create a reader on that connection
		rdconn := bufio.NewReader(conn)

		// Read the payload buffer format
		payloadFormatLen := 1
		payloadFormat := make([]byte, payloadFormatLen)
		n, err := io.ReadFull(rdconn, payloadFormat)
		if err != nil {
			fmt.Printf("\nTCP: can't read format: \n%v\n", err)
			conn.Close()
			continue
		}
		if n != payloadFormatLen {
			fmt.Printf("\nTCP: can't read format: %d/%d\n", n, payloadFormatLen)
			conn.Close()
			continue
		}
		if payloadFormat[0] != BuffFormatPBArray {
			fmt.Printf("\n%s TCP request from %s ignored\n", LogTime(), ipv4(conn.RemoteAddr().String()))
			buf1 := make([]byte, 1024)
			n, err := rdconn.Read(buf1)
			if err == nil || err == io.EOF || err == io.ErrUnexpectedEOF {
				buf2 := append(payloadFormat, buf1[:n]...)
				b := make([]byte, len(buf2))
				var bl int
				var ch, chPrev byte
				for i := 0; i < len(buf2); i++ {
					ch = buf2[i]
					if ch < 32 || ch >= 127 {
						if chPrev == ';' {
							ch = ' '
						} else {
							ch = ';'
						}
					}
					if ch != ' ' || chPrev != ' ' {
						b[bl] = ch
						bl++
					}
					chPrev = ch
				}
				if bl != 0 {
					fmt.Printf("%s\n", string(b[:bl]))
				}
			}
			conn.Close()
			continue
		}

		// Read the number of array entries
		payloadCountLen := 1
		payloadCount := make([]byte, payloadCountLen)
		n, err = io.ReadFull(rdconn, payloadCount)
		if err != nil {
			fmt.Printf("\nTCP: can't read count: \n%v\n", err)
			conn.Close()
			continue
		}
		if n != payloadCountLen {
			fmt.Printf("\nTCP: can't read count: %d/%d\n", n, payloadCountLen)
			conn.Close()
			continue
		}
		if payloadCount[0] == 0 {
			fmt.Printf("\nTCP: unsupported count: %d\n", payloadCount[0])
			conn.Close()
			continue
		}

		// Read the length array
		payloadEntryLengthsLen := int(payloadCount[0])
		payloadEntryLengths := make([]byte, payloadEntryLengthsLen)
		n, err = io.ReadFull(rdconn, payloadEntryLengths)
		if err != nil {
			fmt.Printf("\nTCP: can't read entry_lengths: \n%v\n", err)
			conn.Close()
			continue
		}
		if n != int(payloadEntryLengthsLen) {
			fmt.Printf("\nTCP: can't read entry_lengths: %d/%d\n", n, payloadEntryLengthsLen)
			conn.Close()
			continue
		}

		// Read the entries
		payloadEntriesLen := 0
		for i := 0; i < int(payloadEntryLengthsLen); i++ {
			payloadEntriesLen += int(payloadEntryLengths[i])
		}
		payloadEntries := make([]byte, payloadEntriesLen)
		n, err = io.ReadFull(rdconn, payloadEntries)
		if err != nil {
			fmt.Printf("\nTCP: can't read entries: \n%v\n", err)
			conn.Close()
			continue
		}
		if n != payloadEntriesLen {
			fmt.Printf("\nTCP: can't read entries: %d/%d\n", n, payloadEntriesLen)
			conn.Close()
			continue
		}

		// Combine all that we've read
		payload := append(payloadFormat, payloadCount...)
		payload = append(payload, payloadEntryLengths...)
		payload = append(payload, payloadEntries...)

		// Initialize a new AppReq
		AppReq := IncomingAppReq{}
		AppReq.SvTransport = "device-tcp:" + ipv4(conn.RemoteAddr().String())

		// Push it to be processed
		go AppReqPushPayload(AppReq, payload, "device directly")
		stats.Count.TCP++

		// Close the connection
		conn.Close()

	}

}