Early response parsing work

bufaddr_test.go

@@ -0,0 +1,33 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+package go3270
+
+import (
+	"testing"
+)
+
+func TestEncode(t *testing.T) {
+	encoded := getpos(0, 0)
+	if encoded[0] != 0x40 || encoded[1] != 0x40 {
+		t.Error("Position (0, 0) not correctly encoded")
+	}
+
+	encoded = getpos(11, 39)
+	if encoded[0] != 0x4e || encoded[1] != 0xd7 {
+		t.Error("Position (11, 39) not correctly encoded")
+	}
+}
+
+func TestDecode(t *testing.T) {
+	decoded := decodeBufAddr([2]byte{0x40, 0x40})
+	if decoded != 0 {
+		t.Error("Buffer address incorrectly decoded")
+	}
+
+	decoded = decodeBufAddr([2]byte{0x4e, 0xd7})
+	if decoded != 919 {
+		t.Error("Buffer address incorrectly decoded")
+	}
+}

example/example.go

@@ -7,14 +7,22 @@ package main
 import (
 	"fmt"
 	"net"
+	"os"
 
 	"github.com/racingmars/go3270"
 )
 
+func init() {
+	go3270.Debug = os.Stderr
+}
+
+// A Screen is an array of go3270.Field structs:
 var loginScreen = go3270.Screen{
-	{Row: 0, Col: 0, Intense: true, Content: "Testing . . ."},
+	{Row: 0, Col: 30, Intense: true, Content: "3270 Example Screen"},
-	{Row: 1, Col: 0, Content: "Name    . . ."},
+	{Row: 1, Col: 0, Content: "First Name  . . ."},
-	{Row: 1, Col: 14, Name: "name", Write: true},
+	{Row: 1, Col: 18, Name: "fname", Write: true, Content: "Test"},
+	{Row: 2, Col: 0, Content: "Last Name . . . ."},
+	{Row: 2, Col: 18, Name: "lname", Write: true},
 }
 
 func main() {
@@ -35,21 +43,11 @@ func handle(conn net.Conn) {
 	defer conn.Close()
 
 	go3270.NegotiateTelnet(conn)
-	err := go3270.WriteScreen(loginScreen, 10, 15, conn)
+	_, err := go3270.ShowScreen(loginScreen, nil, 1, 19, conn)
 	if err != nil {
 		panic(err)
 	}
 
-	for {
+	fmt.Println("Connection closed")
-		rbuf := make([]byte, 255)
-		n, err := conn.Read(rbuf)
-		if err != nil {
-			break
-		}
-		for i := 0; i < n; i++ {
-			fmt.Printf("%x", rbuf[i])
-		}
-		fmt.Printf("\n")
-	}
 
 }

response.go

@@ -0,0 +1,192 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+package go3270
+
+import (
+	"bytes"
+	"net"
+)
+
+// Response encapsulates data received from a 3270 client in response to the
+// previously sent screen.
+type Response struct {
+	// Which Action ID key did the user press?
+	AID AID
+
+	// Row the cursor was on (0-based).
+	Row int
+
+	// Column the cursor was on (0-based).
+	Col int
+
+	// Field values.
+	Values map[string]string
+}
+
+// AID is an Action ID character.
+type AID byte
+
+const (
+	AIDNone  AID = 0x60
+	AIDEnter AID = 0x7D
+	AIDPF1   AID = 0xF1
+	AIDPF2   AID = 0xF2
+	AIDPF3   AID = 0xF3
+	AIDPF4   AID = 0xF4
+	AIDPF5   AID = 0xF5
+	AIDPF6   AID = 0xF6
+	AIDPF7   AID = 0xF7
+	AIDPF8   AID = 0xF8
+	AIDPF9   AID = 0xF9
+	AIDPF10  AID = 0x7A
+	AIDPF11  AID = 0x7B
+	AIDPF12  AID = 0x7C
+	AIDPF13  AID = 0xC1
+	AIDPF14  AID = 0xC2
+	AIDPF15  AID = 0xC3
+	AIDPF16  AID = 0xC4
+	AIDPF17  AID = 0xC5
+	AIDPF18  AID = 0xC6
+	AIDPF19  AID = 0xC7
+	AIDPF20  AID = 0xC8
+	AIDPF21  AID = 0xC9
+	AIDPF22  AID = 0x4A
+	AIDPF23  AID = 0x4B
+	AIDPF24  AID = 0x4C
+	AIDPA1   AID = 0x6C
+	AIDPA2   AID = 0x6E
+	AIDPA3   AID = 0x6B
+	AIDClear AID = 0x6D
+)
+
+func readResponse(c net.Conn) (Response, error) {
+	var r Response
+	aid, err := readAID(c)
+	if err != nil {
+		return r, err
+	}
+	r.AID = aid
+
+	row, col, _, err := readPosition(c)
+	if err != nil {
+		return r, err
+	}
+	r.Col = col
+	r.Row = row
+
+	if err = readFields(c); err != nil {
+		return r, err
+	}
+
+	return r, nil
+}
+
+func readAID(c net.Conn) (AID, error) {
+	buf := make([]byte, 1)
+	for {
+		_, err := c.Read(buf)
+		if err != nil {
+			return AIDNone, err
+		}
+		b := buf[0]
+		if (b == 0x60) || (b >= 0x6b && b <= 0x6e) ||
+			(b >= 0x7a && b <= 0x7d) || (b >= 0x4a && b <= 0x4c) ||
+			(b >= 0xf1 && b <= 0xf9) || (b >= 0xc1 && b <= 0xc9) {
+			// We found a valid AID
+			debugf("Got AID byte: %x\n", b)
+			return AID(b), nil
+		}
+		// Consume non-AID bytes continuing loop
+		debugf("Got non-AID byte: %x\n", b)
+	}
+}
+
+func readPosition(c net.Conn) (row, col, addr int, err error) {
+	buf := make([]byte, 1)
+	raw := make([]byte, 2)
+
+	// Read two bytes
+	for i := 0; i < 2; i++ {
+		if _, err := c.Read(buf); err != nil {
+			return 0, 0, 0, err
+		}
+		raw[i] = buf[0]
+	}
+
+	// Decode the raw position
+	addr = decodeBufAddr([2]byte{raw[0], raw[1]})
+	row = addr % 80
+	col = (addr - row) / 80
+
+	debugf("Got position bytes %02x %02x, decoded to %d\n", raw[0], raw[1],
+		addr)
+
+	return row, col, addr, nil
+}
+
+func readFields(c net.Conn) error {
+	buf := make([]byte, 1)
+	var infield bool
+	var fieldpos int
+	var fieldval bytes.Buffer
+	var err error
+
+	// consume bytes until we get 0xffef
+	for {
+		// Read a byte
+		if _, err = c.Read(buf); err != nil {
+			return err
+		}
+
+		// Check for end of data stream (0xffef)
+		if buf[0] == 0xff {
+			// Finish the current field
+			if infield {
+				// TODO
+				debugf("Field %d: %s\n", fieldpos, e2a(fieldval.Bytes()))
+			}
+
+			// consume the next byte, which is probably 0xef
+			if _, err = c.Read(buf); err != nil {
+				return err
+			}
+			return nil
+		}
+
+		// No? Check for start-of-field
+		if buf[0] == 0x11 {
+			// Finish the previous field, if necessary
+			if infield {
+				// TODO
+				debugf("Field %d: %s\n", fieldpos, e2a(fieldval.Bytes()))
+			}
+			// Start a new field
+			infield = true
+			fieldval = bytes.Buffer{}
+			fieldpos = 0
+
+			if _, _, fieldpos, err = readPosition(c); err != nil {
+				return err
+			}
+			continue
+		}
+
+		// Consume all other bytes as field contents if we're in a field
+		if !infield {
+			debugf("Got unexpected byte while processing fields: %02x\n", buf[0])
+			continue
+		}
+		fieldval.WriteByte(buf[0])
+
+	}
+}
+
+// decodeBufAddr decodes a raw 2-byte encoded buffer address and returns the
+// integer value of the address (i.e. 0-1919)
+func decodeBufAddr(raw [2]byte) int {
+	hi := decodes[raw[0]] << 6
+	lo := decodes[raw[1]]
+	return hi | lo
+}

screen.go

@@ -7,7 +7,7 @@ package go3270
 import (
 	"bytes"
 	"fmt"
-	"io"
+	"net"
 )
 
 // Field is a field on the 3270 screen.
@@ -41,13 +41,19 @@ type Field struct {
 // names,
 type Screen []Field
 
-// WriteScreen writes the 3270 datastream for the screen to a writer. Fields
+// ShowScreen writes the 3270 datastream for the screen to a connection.
-// that aren't valid (e.g. outside of the 24x80 screen) are silently ignored.
+// Fields that aren't valid (e.g. outside of the 24x80 screen) are silently
-// After writing the fields, the curser is set to crow, ccol, which are
+// ignored. If a named field has an entry in the values map, the content of
-// 0-based positions: row 0-23 and col 0-79. Errors from io.Writer.Write()
+// the field from the values map is used INSTEAD OF the Field struct's Content
-// are returned if encountered.
+// field. The values map may be nil if no overrides are needed. After writing
-func WriteScreen(screen Screen, crow, ccol int, w io.Writer) error {
+// the fields, the cursor is set to crow, ccol, which are 0-based positions:
+// row 0-23 and col 0-79. Errors from conn.Write() are returned if
+// encountered.
+func ShowScreen(screen Screen, values map[string]string, crow, ccol int,
+	conn net.Conn) (Response, error) {
+
 	var b bytes.Buffer
+	var fieldmap = make(map[int]string) // field buffer positions -> name
 
 	b.WriteByte(0xf5) // Erase/Write to terminal
 	b.WriteByte(0xc3) // WCC = Reset, Unlock Keyboard, Reset MDT
@@ -61,8 +67,23 @@ func WriteScreen(screen Screen, crow, ccol int, w io.Writer) error {
 
 		b.Write(sba(fld.Row, fld.Col))
 		b.Write(sf(fld.Write, fld.Intense))
-		if fld.Content != "" {
+
-			b.Write(a2e([]byte(fld.Content)))
+		// Use fld.Content, unless the field is named and appears in the
+		// value map.
+		content := fld.Content
+		if fld.Name != "" {
+			if val, ok := values[fld.Name]; ok {
+				content = val
+			}
+		}
+		if content != "" {
+			b.Write(a2e([]byte(content)))
+		}
+
+		// If a writable field, add it to the field map
+		if fld.Write {
+			bufaddr := fld.Row*80 + fld.Col
+			fieldmap[bufaddr] = fld.Name
 		}
 	}
 
@@ -73,14 +94,33 @@ func WriteScreen(screen Screen, crow, ccol int, w io.Writer) error {
 	if ccol < 0 || ccol > 79 {
 		ccol = 0
 	}
-	//b.Write(ic(crow, ccol))
+	b.Write(ic(crow, ccol))
 
 	b.Write([]byte{0xff, 0xef}) // Telnet IAC EOR
 
 	// Now write the datastream to the writer, returning any potential error.
-	fmt.Printf("%x\n", b.Bytes())
+	if Debug != nil {
-	_, err := w.Write(b.Bytes())
+		fmt.Fprintf(Debug, "%x\n", b.Bytes())
-	return err
+	}
+	if _, err := conn.Write(b.Bytes()); err != nil {
+		return Response{}, err
+	}
+
+	// Now wait for the response. We want to read bytes that start with an AID
+	// and end with 0xFFEF.
+	// for {
+	// 	rbuf := make([]byte, 1)
+	// 	n, err := conn.Read(rbuf)
+	// 	if err != nil {
+	// 		return Response{}, err
+	// 	}
+	// 	for i := 0; i < n; i++ {
+	// 		fmt.Printf("%x", rbuf[i])
+	// 	}
+	// 	fmt.Printf("\n")
+	// }
+
+	return readResponse(conn)
 }
 
 // sba is the "set buffer address" 3270 command.
@@ -97,6 +137,11 @@ func sf(write, intense bool) []byte {
 	result[0] = 0x1d // SF
 	if !write {
 		result[1] |= 1 << 5 // set "bit 2"
+	} else {
+		// The MDT bit -- we always want writable field values returned,
+		// even if unchanged
+		result[1] |= 1 // set "bit 7"
+
 	}
 	if intense {
 		result[1] |= 1 << 3 // set "bit 4"
@@ -126,11 +171,15 @@ func getpos(row, col int) []byte {
 	return result
 }
 
-// codes are the 3270 control character I/O codes, pre-computed as provided
+type readerState int
-// at http://www.tommysprinkle.com/mvs/P3270/iocodes.htm
+
-var codes = []byte{0x40, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8,
+const (
-	0xc9, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0xd1, 0xd2, 0xd3, 0xd4,
+	stateNone readerState = iota
-	0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60,
+	stateGotAID
-	0x61, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0x6a, 0x6b, 0x6c,
+	stateGotFirstAddr
-	0x6d, 0x6e, 0x6f, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
+	stateGotSecondAddr
-	0xf9, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f}
+	stateInField
+	stateGotFirstFieldAddr
+	stateGotSecondFieldAddr
+	stateGot
+)

util.go

@@ -0,0 +1,46 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+package go3270
+
+import (
+	"fmt"
+	"io"
+)
+
+var Debug io.Writer
+
+func debugf(format string, a ...interface{}) {
+	if Debug == nil {
+		return
+	}
+
+	fmt.Fprintf(Debug, format, a...)
+}
+
+// codes are the 3270 control character I/O codes, pre-computed as provided
+// at http://www.tommysprinkle.com/mvs/P3270/iocodes.htm
+var codes = []byte{0x40, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8,
+	0xc9, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0xd1, 0xd2, 0xd3, 0xd4,
+	0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60,
+	0x61, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0x6a, 0x6b, 0x6c,
+	0x6d, 0x6e, 0x6f, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
+	0xf9, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f}
+
+// decodes is the inverse of the above table; -1 is used in invalid positions
+var decodes = []int{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, 16, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, -1, -1, -1, -1, -1, -1,
+	-1, -1, 42, 43, 44, 45, 46, 47, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	58, 59, 60, 61, 62, 63, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2,
+	3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 17, 18, 19, 20, 21, 22,
+	23, 24, 25, -1, -1, -1, -1, -1, -1, -1, -1, 34, 35, 36, 37, 38, 39, 40,
+	41, -1, -1, -1, -1, -1, -1, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, -1,
+	-1, -1, -1, -1}