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
+ Password string // Tracker password, if required by tracker
+
+ 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),
+ []byte{uint8(len(tr.Password))},
+ []byte(tr.Password),
)
+
+ 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: %v", 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:
// 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
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 {
// 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) {
+ 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]
git.r.bdr.sh / rbdr / mobius / blobdiff