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glutton.go
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glutton.go
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package glutton
import (
"bytes"
"context"
_ "embed"
"fmt"
"io"
"log/slog"
"net"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/mushorg/glutton/connection"
"github.com/mushorg/glutton/producer"
"github.com/mushorg/glutton/protocols"
"github.com/mushorg/glutton/rules"
"github.com/google/uuid"
"github.com/seud0nym/tproxy-go/tproxy"
"github.com/spf13/viper"
)
// Glutton struct
type Glutton struct {
id uuid.UUID
Logger *slog.Logger
Server *Server
rules rules.Rules
Producer *producer.Producer
connTable *connection.ConnTable
tcpProtocolHandlers map[string]protocols.TCPHandlerFunc
udpProtocolHandlers map[string]protocols.UDPHandlerFunc
ctx context.Context
cancel context.CancelFunc
publicAddrs []net.IP
}
//go:embed config/rules.yaml
var defaultRules []byte
func (g *Glutton) initConfig() error {
viper.SetConfigName("config")
viper.AddConfigPath(viper.GetString("confpath"))
if _, err := os.Stat(viper.GetString("confpath")); !os.IsNotExist(err) {
if err := viper.ReadInConfig(); err != nil {
return err
}
}
// If no config is found, use the defaults
viper.SetDefault("ports.tcp", 5000)
viper.SetDefault("ports.udp", 5001)
viper.SetDefault("max_tcp_payload", 4096)
viper.SetDefault("conn_timeout", 45)
viper.SetDefault("rules_path", "rules/rules.yaml")
g.Logger.Debug("configuration set successfully", slog.String("reporter", "glutton"))
return nil
}
// New creates a new Glutton instance
func New(ctx context.Context) (*Glutton, error) {
g := &Glutton{
tcpProtocolHandlers: make(map[string]protocols.TCPHandlerFunc),
udpProtocolHandlers: make(map[string]protocols.UDPHandlerFunc),
connTable: connection.New(),
}
g.ctx, g.cancel = context.WithCancel(ctx)
if err := g.makeID(); err != nil {
return nil, err
}
g.Logger = producer.NewLogger(g.id.String())
// Loading the configuration
g.Logger.Info("Loading configurations from: config/config.yaml", slog.String("reporter", "glutton"))
if err := g.initConfig(); err != nil {
return nil, err
}
var rulesFile io.ReadCloser
rulesPath := viper.GetString("rules_path")
if _, err := os.Stat(rulesPath); !os.IsNotExist(err) {
rulesFile, err = os.Open(rulesPath)
if err != nil {
return nil, err
}
defer rulesFile.Close()
} else {
g.Logger.Warn("No rules file found, using default rules", slog.String("reporter", "glutton"))
rulesFile = io.NopCloser(bytes.NewBuffer(defaultRules))
}
var err error
g.rules, err = rules.ParseRuleSpec(rulesFile)
if err != nil {
return nil, err
}
for idx, rule := range g.rules {
if err := rules.InitRule(idx, rule); err != nil {
return nil, fmt.Errorf("failed to initialize rule: %w", err)
}
}
return g, nil
}
// Init initializes server and handles
func (g *Glutton) Init() error {
var err error
g.publicAddrs, err = getNonLoopbackIPs(viper.GetString("interface"))
if err != nil {
return err
}
for _, sIP := range viper.GetStringSlice("addresses") {
if ip := net.ParseIP(sIP); ip != nil {
g.publicAddrs = append(g.publicAddrs, ip)
}
}
// Start the Glutton server
tcpServerPort := uint(viper.GetInt("ports.tcp"))
udpServerPort := uint(viper.GetInt("ports.udp"))
g.Server = NewServer(tcpServerPort, udpServerPort)
if err := g.Server.Start(); err != nil {
return err
}
// Initiating log producers
if viper.GetBool("producers.enabled") {
g.Producer, err = producer.New(g.id.String())
if err != nil {
return err
}
}
// Initiating protocol handlers
g.tcpProtocolHandlers = protocols.MapTCPProtocolHandlers(g.Logger, g)
g.udpProtocolHandlers = protocols.MapUDPProtocolHandlers(g.Logger, g)
return nil
}
func (g *Glutton) udpListen() {
buffer := make([]byte, 1024)
for {
n, srcAddr, dstAddr, err := tproxy.ReadFromUDP(g.Server.udpListener, buffer)
if err != nil {
g.Logger.Error("failed to read UDP packet", producer.ErrAttr(err))
}
rule, err := g.applyRules("udp", srcAddr, dstAddr)
if err != nil {
g.Logger.Error("failed to apply rules", producer.ErrAttr(err))
}
if rule == nil {
rule = &rules.Rule{Target: "udp"}
}
md, err := g.connTable.Register(srcAddr.IP.String(), strconv.Itoa(int(srcAddr.AddrPort().Port())), dstAddr.AddrPort().Port(), rule)
if err != nil {
g.Logger.Error("failed to register UDP packet", producer.ErrAttr(err))
}
if hfunc, ok := g.udpProtocolHandlers[rule.Target]; ok {
data := buffer[:n]
go func() {
if err := hfunc(g.ctx, srcAddr, dstAddr, data, md); err != nil {
g.Logger.Error("failed to handle UDP payload", producer.ErrAttr(err))
}
}()
}
}
}
// Start the listener, this blocks for new connections
func (g *Glutton) Start() error {
quit := make(chan struct{}) // stop monitor on shutdown
defer func() {
quit <- struct{}{}
g.Shutdown()
}()
g.startMonitor(quit)
if err := setTProxyIPTables(viper.GetString("interface"), g.publicAddrs[0].String(), "tcp", uint32(g.Server.tcpPort)); err != nil {
return err
}
if err := setTProxyIPTables(viper.GetString("interface"), g.publicAddrs[0].String(), "udp", uint32(g.Server.udpPort)); err != nil {
return err
}
go g.udpListen()
for {
select {
case <-g.ctx.Done():
return nil
default:
}
conn, err := g.Server.tcpListener.Accept()
if err != nil {
return err
}
rule, err := g.applyRulesOnConn(conn)
if err != nil {
return fmt.Errorf("failed to apply rules: %w", err)
}
if rule == nil {
rule = &rules.Rule{Target: "default"}
}
md, err := g.connTable.RegisterConn(conn, rule)
if err != nil {
return err
}
g.Logger.Debug("new connection", slog.String("addr", conn.LocalAddr().String()), slog.String("handler", rule.Target))
g.ctx = context.WithValue(g.ctx, ctxTimeout("timeout"), int64(viper.GetInt("conn_timeout")))
if err := g.UpdateConnectionTimeout(g.ctx, conn); err != nil {
g.Logger.Error("failed to set connection timeout", producer.ErrAttr(err))
}
if hfunc, ok := g.tcpProtocolHandlers[rule.Target]; ok {
go func() {
if err := hfunc(g.ctx, conn, md); err != nil {
g.Logger.Error("failed to handle TCP connection", producer.ErrAttr(err), slog.String("handler", rule.Target))
}
}()
}
}
}
func (g *Glutton) makeID() error {
filePath := filepath.Join(viper.GetString("var-dir"), "glutton.id")
if err := os.MkdirAll(viper.GetString("var-dir"), 0744); err != nil {
return fmt.Errorf("failed to create var-dir: %w", err)
}
if _, err := os.Stat(filePath); os.IsNotExist(err) {
g.id = uuid.New()
data, err := g.id.MarshalBinary()
if err != nil {
return fmt.Errorf("failed to marshal UUID: %w", err)
}
if err := os.WriteFile(filePath, data, 0744); err != nil {
return fmt.Errorf("failed to create new PID file: %w", err)
}
} else {
if err != nil {
return fmt.Errorf("failed to access PID file: %w", err)
}
f, err := os.Open(filePath)
if err != nil {
return fmt.Errorf("failed to open PID file: %w", err)
}
buff, err := io.ReadAll(f)
if err != nil {
return fmt.Errorf("failed to read PID file: %w", err)
}
g.id, err = uuid.FromBytes(buff)
if err != nil {
return fmt.Errorf("failed to create UUID from PID filed content: %w", err)
}
}
return nil
}
type ctxTimeout string
// UpdateConnectionTimeout increase connection timeout limit on connection I/O operation
func (g *Glutton) UpdateConnectionTimeout(ctx context.Context, conn net.Conn) error {
if timeout, ok := ctx.Value(ctxTimeout("timeout")).(int64); ok {
if err := conn.SetDeadline(time.Now().Add(time.Duration(timeout) * time.Second)); err != nil {
return err
}
}
return nil
}
// ConnectionByFlow returns connection metadata by connection key
func (g *Glutton) ConnectionByFlow(ckey [2]uint64) connection.Metadata {
return g.connTable.Get(ckey)
}
// MetadataByConnection returns connection metadata by connection
func (g *Glutton) MetadataByConnection(conn net.Conn) (connection.Metadata, error) {
host, port, err := net.SplitHostPort(conn.RemoteAddr().String())
if err != nil {
return connection.Metadata{}, fmt.Errorf("faild to split remote address: %w", err)
}
ckey, err := connection.NewConnKeyByString(host, port)
if err != nil {
return connection.Metadata{}, err
}
md := g.ConnectionByFlow(ckey)
return md, nil
}
func (g *Glutton) sanitizePayload(payload []byte) []byte {
for _, ip := range g.publicAddrs {
payload = []byte(strings.ReplaceAll(string(payload), ip.String(), "1.2.3.4"))
}
return payload
}
func (g *Glutton) ProduceTCP(handler string, conn net.Conn, md connection.Metadata, payload []byte, decoded interface{}) error {
if g.Producer != nil {
payload = g.sanitizePayload(payload)
return g.Producer.LogTCP(handler, conn, md, payload, decoded)
}
return nil
}
func (g *Glutton) ProduceUDP(handler string, srcAddr, dstAddr *net.UDPAddr, md connection.Metadata, payload []byte, decoded interface{}) error {
if g.Producer != nil {
payload = g.sanitizePayload(payload)
return g.Producer.LogUDP("udp", srcAddr, dstAddr, md, payload, decoded)
}
return nil
}
// Shutdown the packet processor
func (g *Glutton) Shutdown() {
g.cancel() // close all connection
g.Logger.Info("Shutting down listeners")
if err := g.Server.Shutdown(); err != nil {
g.Logger.Error("failed to shutdown server", producer.ErrAttr(err))
}
g.Logger.Info("FLushing TCP iptables")
if err := flushTProxyIPTables(viper.GetString("interface"), g.publicAddrs[0].String(), "tcp", uint32(g.Server.tcpPort)); err != nil {
g.Logger.Error("failed to drop tcp iptables", producer.ErrAttr(err))
}
g.Logger.Info("FLushing UDP iptables")
if err := flushTProxyIPTables(viper.GetString("interface"), g.publicAddrs[0].String(), "udp", uint32(g.Server.udpPort)); err != nil {
g.Logger.Error("failed to drop udp iptables", producer.ErrAttr(err))
}
g.Logger.Info("All done")
}
func (g *Glutton) applyRules(network string, srcAddr, dstAddr net.Addr) (*rules.Rule, error) {
match, err := g.rules.Match(network, srcAddr, dstAddr)
if err != nil {
return nil, err
}
if match != nil {
return match, err
}
return nil, nil
}
func (g *Glutton) applyRulesOnConn(conn net.Conn) (*rules.Rule, error) {
return g.applyRules("tcp", conn.RemoteAddr(), conn.LocalAddr())
}