X-Git-Url: https://git.r.bdr.sh/rbdr/mobius/blobdiff_plain/8ff2b66d1583b38298dfa415588df89631023695..a55350daaf83498b7a237c027ad0dd2377f06fee:/hotline/tracker.go

diff --git a/hotline/tracker.go b/hotline/tracker.go
index 4d4c8a6..b927986 100644
--- a/hotline/tracker.go
+++ b/hotline/tracker.go
@@ -4,49 +4,60 @@ import (
 	"bufio"
 	"encoding/binary"
 	"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
 }
 
 func register(tracker string, tr *TrackerRegistration) error {
 	conn, err := net.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
@@ -67,7 +78,7 @@ type TrackerHeader struct {
 	Version  [2]byte // Old protocol (1) or new (2)
 }
 
-// Message type	2	1	Sending list of servers
+// 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
@@ -83,8 +94,8 @@ type ServerRecord struct {
 	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
 }
@@ -124,8 +135,12 @@ func GetListing(addr string) ([]ServerRecord, error) {
 	var servers []ServerRecord
 	for {
 		scanner.Scan()
+
 		var srv ServerRecord
-		_, _ = srv.Read(scanner.Bytes())
+		_, err = srv.Write(scanner.Bytes())
+		if err != nil {
+			return nil, err
+		}
 
 		servers = append(servers, srv)
 		if len(servers) == totalSrv {
@@ -146,22 +161,34 @@ func GetListing(addr string) ([]ServerRecord, error) {
 // 00000050  4f 54 4c 2e 63 6f 6d 3a  35 35 30 30 2d 4f 3a b2  |OTL.com:5500-O:.|
 // 00000060  15 7c 00 00 00 00 08 53  65 6e 65 63 74 75 73 20  |.|.....Senectus |
 func serverScanner(data []byte, _ bool) (advance int, token []byte, err error) {
+	// The name length field is the 11th byte of the server record.  If we don't have that many bytes,
+	// return nil token so the Scanner reads more data and continues scanning.
 	if len(data) < 10 {
 		return 0, nil, nil
 	}
 
 	// A server entry has two variable length fields: the name and description.
-	// To get the token length, we first need the name length from the 10th byte:
+	// To get the token length, we first need the name length from the 10th byte
 	nameLen := int(data[10])
 
+	// The description length field is at the 12th + nameLen byte of the server record.
+	// If we don't have that many bytes, return nil token so the Scanner reads more data and continues scanning.
+	if len(data) < 11+nameLen {
+		return 0, nil, nil
+	}
+
 	// Next we need the description length from the 11+nameLen byte:
 	descLen := int(data[11+nameLen])
 
+	if len(data) < 12+nameLen+descLen {
+		return 0, nil, nil
+	}
+
 	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) {
 	copy(s.IPAddr[:], b[0:4])
 	copy(s.Port[:], b[4:6])
 	copy(s.NumUsers[:], b[6:8])