Extensive refactor, quality of life enhancements

[rbdr/mobius] / hotline / tracker.go

diff --git a/hotline/tracker.go b/hotline/tracker.go
index bd7aa00da966d52b21f1a2b872d3153e78348884..2d655d97b5762c26ddd16a078b5f1033447d2a5a 100644 (file)
--- a/hotline/tracker.go
+++ b/hotline/tracker.go
@@ -3,57 +3,78 @@ package hotline
 import (
        "bufio"
        "encoding/binary"
 import (
        "bufio"
        "encoding/binary"

+       "errors"

        "fmt"
        "fmt"

-       "github.com/jhalter/mobius/concat"
+       "io"

        "net"
        "net"

+       "slices"

        "strconv"
        "strconv"

-       "time"

 )
 
 // TrackerRegistration represents the payload a Hotline server sends to a Tracker to register
 type TrackerRegistration struct {
 )
 
 // 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
        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
        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))
 
        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,
                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.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 {
        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
 }
 
        }
 
        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:
 // 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)
 
 // 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)
 }
 
 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 {
 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)_/¯
 }
 
        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
 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
 }
 
        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() }()
 
        defer func() { _ = conn.Close() }()
 

-       _, err = conn.Write(
+       _, err := conn.Write(

                []byte{
                        0x48, 0x54, 0x52, 0x4B, // HTRK
                        0x00, 0x01, // Version
                []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 servers []ServerRecord
        for {
                scanner.Scan()

+

                var srv ServerRecord
                var srv ServerRecord

-               _, err = srv.Read(scanner.Bytes())
+               _, err = srv.Write(scanner.Bytes())

                if err != nil {
                        return nil, err
                }
                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
 }
 
        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])
        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]
        nameLen := int(b[10])
 
        s.Name = b[11 : 11+nameLen]