/
MasterInfo.go
346 lines (270 loc) · 8.77 KB
/
MasterInfo.go
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package protocol
import (
"encoding/binary"
"fmt"
"math"
"net"
"sort"
"strconv"
"strings"
"github.com/StarsiegePlayers/darkstar-query-go/v2/server"
)
type Master struct {
*Packet `json:"-" csv:"-"`
Address string
CommonName string
MOTDJunk string `json:"-" csv:"-"`
MOTD string
Servers map[string]*server.Server
MasterID uint16
}
func NewMasterWithAddress(address string) (output *Master) {
output = NewMaster()
output.Address = address
return
}
func NewMaster() (output *Master) {
output = new(Master)
output.Servers = make(map[string]*server.Server)
output.MOTDJunk = "0000000000" // anything except all <0x00> will show the MOTD
output.Packet = NewPacket()
return
}
func (m *Master) UnmarshalBinarySet(data [][]byte) (err error) {
for _, v := range data {
err = m.UnmarshalBinary(v)
if err != nil {
return err
}
}
return
}
func (m *Master) UnmarshalBinary(data []byte) (err error) {
err = m.Packet.UnmarshalBinary(data)
if err != nil {
return
}
p := m.Packet
m.MasterID = p.ID
if len(p.Data) <= 2 {
return
}
// if it's the first packet (and only the first packet)
// parse out the common name and MOTD
if p.Number == 1 {
m.CommonName, p.Data = ReadPascalStringStream(p.Data)
m.CommonName = strings.ReplaceAll(m.CommonName, `\n`, "")
m.MOTD, p.Data = ReadPascalStringStream(p.Data)
m.MOTD = strings.ReplaceAll(m.MOTD, `\n`, " ")
if len(m.MOTD) > 10 {
// the first 10 characters are classified as "junk"
m.MOTDJunk, m.MOTD = m.MOTD[0:10], m.MOTD[10:]
}
}
if len(p.Data) == 0 {
return
}
p.Data = p.Data[1:] // null header separator
serverCount := byte(0)
serverCount, p.Data = p.Data[0], p.Data[1:]
if serverCount <= 0 || len(p.Data) == 0 {
return
}
for i := byte(0); i < serverCount; i++ {
p.Data = p.Data[1:] // skip separator byte "0x6"
address := fmt.Sprintf("%d.%d.%d.%d", p.Data[0], p.Data[1], p.Data[2], p.Data[3])
port := fmt.Sprintf("%d", binary.LittleEndian.Uint16(p.Data[4:4+2]))
addressPort := fmt.Sprintf("%s:%s", address, port)
p.Data = p.Data[6:]
if address == "127.0.0.1" { // skip all servers reporting as localhost
continue
}
svr, err := server.NewServerFromString(addressPort)
if err != nil {
continue
}
m.Servers[addressPort] = svr
}
// log.Printf("Servercount: %d, datalen %d, countlen %d\n", serverCount, len(data), len(m.ServerAddresses))
return
}
func (m *Master) MarshalBinaryHeader() (output []byte) {
// field 01 - pascal common name, string
commonName := make([]byte, len(m.CommonName)+1)
commonName[0] = byte(len(m.CommonName))
copy(commonName[1:], m.CommonName)
motd := make([]byte, 2)
if len(m.MOTD) > 0 {
// field 02 - pascal MOTD string, incl 10 character spacer
motd = make([]byte, len(m.MOTD)+12)
motd[0] = byte(len(motd) - 2) // exclude size byte and trailer null
copy(motd[1:1+10], m.MOTDJunk) // magic 10 characters
copy(motd[11:len(m.MOTD)+11], m.MOTD)
copy(motd[len(motd)-1:], "\x00")
}
// combine
output = make([]byte, len(commonName)+len(motd))
copy(output, commonName)
copy(output[len(commonName):], motd)
return
}
// MarshalBinarySet generates the body of a darkstar master packet
// laddr is the address of the interface the packet came in on
// raddr is the address of the request
func (m *Master) MarshalBinarySet(options *Options, input map[string]*server.Server, laddr net.Addr, raddr net.Addr) (output []byte) {
set := make([]string, 0)
for k := range input {
set = append(set, k)
}
sort.Strings(set)
// work with a byte buffer
hold := make([]byte, len(set)*7)
// classify the remote ip address
remoteIsLocalNet := false
remoteIsLocalHost := false
// if the local address and remote address are in the same network
if raddr != nil && raddr.(*net.UDPAddr).IP.IsPrivate() {
remoteIsLocalNet = true
}
// if the remote address is in the localhost network "127.0.0.1/8"
if raddr != nil && raddr.(*net.UDPAddr).IP.IsLoopback() {
remoteIsLocalHost = true
}
for index, hostPort := range set {
// split ip:port
stringHost, port, err := net.SplitHostPort(hostPort)
if err != nil {
continue
}
host := net.ParseIP(stringHost)
switch {
// if the remote ip is in a local network, and we're about to send a host from a loopback address
// then substitute out the local ip corresponding to the local network the packet came in on
case remoteIsLocalNet:
if laddr != nil && host.IsLoopback() {
host = laddr.(*net.UDPAddr).IP
}
// if we have a STUN IP, and we've gotten our networks correctly
// and if the remote ip isn't from either localhost or a local network
// then substitute out the local ip address for the address received via STUN
case options.ExternalIP != nil && options.LocalNetworks != nil && !remoteIsLocalHost && !remoteIsLocalNet:
for _, v := range options.LocalNetworks {
if v.Contains(host) {
host = options.ExternalIP
}
}
}
// individual entry byte buffer
out := make([]byte, 7)
// <length: 0x06><4 bytes ipv4 addr><2 bytes port>
out[0] = byte(len(out) - 1)
copy(out[1:], host.To4())
// ports are sent as a uint16 little endian stream
p, _ := strconv.Atoi(port)
binary.LittleEndian.PutUint16(out[5:], uint16(p))
// current entry * length of entry : current entry * length of entry + length of entry
copy(hold[index*7:index*7+7], out)
}
output = make([]byte, len(hold)+1)
output[0] = byte(len(set))
copy(output[1:], hold)
return
}
func (m *Master) GeneratePackets(options *Options, key uint16, laddr net.Addr, raddr net.Addr) [][]byte {
serverAddresses := make([]string, 0)
for k := range m.Servers {
serverAddresses = append(serverAddresses, k)
}
sort.Strings(serverAddresses)
output := make([][]byte, 0)
// generate header
header := m.MarshalBinaryHeader()
firstPacketOverhead := uint16(len(header) + HeaderSize + 2) // uint16 little endian trailer for payload length
// calculate packet sizes relative to payload data
// 7 bytes per entry: <0x06 pascal-style entry length in bytes><4 bytes ipv4 address><2 bytes udpPort>
firstPacketMax := (options.MaxServerPacketSize - firstPacketOverhead) / 7
overflowPacketMax := (options.MaxServerPacketSize - (HeaderSize + 2)) / 7
// calculate overflow from first packet
overflowPackets, overflowSize := 0, len(serverAddresses)-int(firstPacketMax)
if overflowSize > 0 {
overflowPackets = int(math.Ceil(float64(overflowSize)/float64(overflowPacketMax))) + 1
}
localAddresses := make([]string, len(serverAddresses))
copy(localAddresses, serverAddresses)
// send first packet
pkt := NewPacket()
pkt.Type = MasterServerList
pkt.ID = m.MasterID
pkt.Key = key
// simple logic for non spanned packets
if overflowPackets <= 0 {
// setting pkt 1 of 1 is distinctly different from ping/game info
pkt.Number = 1
pkt.Total = 1
dataset := m.MarshalBinarySet(options, m.Servers, laddr, raddr)
tempData := make([]byte, len(header)+len(dataset))
copy(tempData[0:len(header)], header)
copy(tempData[len(header):len(header)+len(dataset)], dataset)
pkt.Data = tempData
binOut, err := pkt.MarshalBinary()
if err != nil {
// todo: log
return [][]byte{}
}
output = append(output, binOut)
// exit early
return output
}
// otherwise, time to do some convoluted craziness
pkt.Number = 1 // start at 0x1
pkt.Total = byte(overflowPackets) // overflow packets should be > 2
// deep copy the first subset of addresses
tmpAddresses := make(map[string]*server.Server)
for k, v := range localAddresses {
if uint16(k) >= firstPacketMax {
break
}
tmpAddresses[v] = m.Servers[v]
}
// pop the elements we just copied
localAddresses = localAddresses[firstPacketMax:]
// marshal data
dataset := m.MarshalBinarySet(options, tmpAddresses, laddr, raddr)
tempData := make([]byte, len(header)+len(dataset))
copy(tempData[0:len(header)], header)
copy(tempData[len(header):len(header)+len(dataset)], dataset)
// copy to output
pkt.Data = tempData
binOut, err := pkt.MarshalBinary()
if err != nil {
// todo: log
return [][]byte{}
}
output = append(output, binOut)
// do the above for each overflow packet
for i := 1; i < overflowPackets; i++ {
pkt.Number++ // increment packet number
// make sure we don't exceed the array for the last packet
if uint16(len(localAddresses)) <= overflowPacketMax {
overflowPacketMax = uint16(len(localAddresses))
}
// copy the next subset of overflow addresses
tmpAddresses = make(map[string]*server.Server)
for k, v := range localAddresses {
if uint16(k) >= overflowPacketMax {
break
}
tmpAddresses[v] = m.Servers[v]
}
localAddresses = localAddresses[overflowPacketMax:]
// marshal and send
pkt.Data = m.MarshalBinarySet(options, tmpAddresses, laddr, raddr)
binOut, err = pkt.MarshalBinary()
if err != nil {
// todo: log
return [][]byte{}
}
output = append(output, binOut)
}
return output
}