X-Git-Url: https://git.r.bdr.sh/rbdr/mobius/blobdiff_plain/04f402736027ced9bfbbf628136dc4872b671555..a2ef262a164fc735b9b8471ac0c8001eea2b9bf6:/hotline/tracker.go

diff --git a/hotline/tracker.go b/hotline/tracker.go
index bd7aa00..d0ccff4 100644
--- a/hotline/tracker.go
+++ b/hotline/tracker.go
@@ -3,57 +3,78 @@ package hotline
 import (
 	"bufio"
 	"encoding/binary"
+	"errors"
 	"fmt"
-	"github.com/jhalter/mobius/concat"
+	"io"
 	"net"
+	"slices"
 	"strconv"
-	"time"
 )
 
 // TrackerRegistration represents the payload a Hotline server sends to a Tracker to register
 type TrackerRegistration struct {
-	Port        [2]byte // Server listening port number
+	Port        [2]byte // Server's listening TCP port number
 	UserCount   int     // Number of users connected to this particular server
-	PassID      []byte  // Random number generated by the server
-	Name        string  // Server name
+	PassID      [4]byte // Random number generated by the server
+	Name        string  // Server Name
 	Description string  // Description of the server
+
+	readOffset int // Internal offset to track read progress
 }
 
-// TODO: reimplement as io.Reader
-func (tr *TrackerRegistration) Read() []byte {
+// Read implements io.Reader to write tracker registration payload bytes to slice
+func (tr *TrackerRegistration) Read(p []byte) (int, error) {
 	userCount := make([]byte, 2)
 	binary.BigEndian.PutUint16(userCount, uint16(tr.UserCount))
 
-	return concat.Slices(
-		[]byte{0x00, 0x01},
+	buf := slices.Concat(
+		[]byte{0x00, 0x01}, // Magic number, always 1
 		tr.Port[:],
 		userCount,
-		[]byte{0x00, 0x00},
-		tr.PassID,
+		[]byte{0x00, 0x00}, // Magic number, always 0
+		tr.PassID[:],
 		[]byte{uint8(len(tr.Name))},
 		[]byte(tr.Name),
 		[]byte{uint8(len(tr.Description))},
 		[]byte(tr.Description),
 	)
+
+	if tr.readOffset >= len(buf) {
+		return 0, io.EOF // All bytes have been read
+	}
+
+	n := copy(p, buf[tr.readOffset:])
+	tr.readOffset += n
+
+	return n, nil
+}
+
+// Dialer interface to abstract the dialing operation
+type Dialer interface {
+	Dial(network, address string) (net.Conn, error)
+}
+
+// RealDialer is the real implementation of the Dialer interface
+type RealDialer struct{}
+
+func (d *RealDialer) Dial(network, address string) (net.Conn, error) {
+	return net.Dial(network, address)
 }
 
-func register(tracker string, tr *TrackerRegistration) error {
-	conn, err := net.Dial("udp", tracker)
+func register(dialer Dialer, tracker string, tr io.Reader) error {
+	conn, err := dialer.Dial("udp", tracker)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to dial tracker: %w", err)
 	}
+	defer conn.Close()
 
-	b := tr.Read()
-
-	if _, err := conn.Write(b); err != nil {
-		return err
+	if _, err := io.Copy(conn, tr); err != nil {
+		return fmt.Errorf("failed to write to connection: %w", err)
 	}
 
 	return nil
 }
 
-const trackerTimeout = 5 * time.Second
-
 // All string values use 8-bit ASCII character set encoding.
 // Client Interface with Tracker
 // After establishing a connection with tracker, the following information is sent:
@@ -61,42 +82,35 @@ const trackerTimeout = 5 * time.Second
 // Magic number	4	‘HTRK’
 // Version	2	1 or 2	Old protocol (1) or new (2)
 
-// Reply received from the tracker starts with a header:
+// TrackerHeader is sent in reply Reply received from the tracker starts with a header:
 type TrackerHeader struct {
 	Protocol [4]byte // "HTRK" 0x4854524B
 	Version  [2]byte // Old protocol (1) or new (2)
 }
 
-// Message type	2	1	Sending list of servers
-// Message data size	2		Remaining size of this request
-// Number of servers	2		Number of servers in the server list
-// Number of servers	2		Same as previous field
 type ServerInfoHeader struct {
-	MsgType     [2]byte // always has value of 1
+	MsgType     [2]byte // Always has value of 1
 	MsgDataSize [2]byte // Remaining size of request
 	SrvCount    [2]byte // Number of servers in the server list
 	SrvCountDup [2]byte // Same as previous field ¯\_(ツ)_/¯
 }
 
+// ServerRecord is a tracker listing for a single server
 type ServerRecord struct {
 	IPAddr          [4]byte
 	Port            [2]byte
 	NumUsers        [2]byte // Number of users connected to this particular server
 	Unused          [2]byte
-	NameSize        byte   // Length of name string
-	Name            []byte // Server name
+	NameSize        byte   // Length of Name string
+	Name            []byte // Server Name
 	DescriptionSize byte
 	Description     []byte
 }
 
-func GetListing(addr string) ([]ServerRecord, error) {
-	conn, err := net.DialTimeout("tcp", addr, trackerTimeout)
-	if err != nil {
-		return []ServerRecord{}, err
-	}
+func GetListing(conn io.ReadWriteCloser) ([]ServerRecord, error) {
 	defer func() { _ = conn.Close() }()
 
-	_, err = conn.Write(
+	_, err := conn.Write(
 		[]byte{
 			0x48, 0x54, 0x52, 0x4B, // HTRK
 			0x00, 0x01, // Version
@@ -124,8 +138,9 @@ func GetListing(addr string) ([]ServerRecord, error) {
 	var servers []ServerRecord
 	for {
 		scanner.Scan()
+
 		var srv ServerRecord
-		_, err = srv.Read(scanner.Bytes())
+		_, err = srv.Write(scanner.Bytes())
 		if err != nil {
 			return nil, err
 		}
@@ -175,11 +190,15 @@ func serverScanner(data []byte, _ bool) (advance int, token []byte, err error) {
 	return 12 + nameLen + descLen, data[0 : 12+nameLen+descLen], nil
 }
 
-// Read implements io.Reader for ServerRecord
-func (s *ServerRecord) Read(b []byte) (n int, err error) {
+// Write implements io.Writer for ServerRecord
+func (s *ServerRecord) Write(b []byte) (n int, err error) {
+	if len(b) < 13 {
+		return 0, errors.New("too few bytes")
+	}
 	copy(s.IPAddr[:], b[0:4])
 	copy(s.Port[:], b[4:6])
 	copy(s.NumUsers[:], b[6:8])
+	s.NameSize = b[10]
 	nameLen := int(b[10])
 
 	s.Name = b[11 : 11+nameLen]