commit 83c090c59b30a152927393f40bda5efd0ca6b707 · seiso.moe/alky

.gitignore

README.md

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       # ALKY

     

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       ## IMPORTANT

     

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       #### REQUIRED But not currently supported 

     

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       - imperative mode for resolving

     

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           - i would support this as required by 1034 section 4.3.1 (https://datatracker.ietf.org/doc/html/rfc1034#section-4.3.1) but it does not look like any of the servers i have queried support this (cloudflare, google, quad9)

+17

docs/alky.toml

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       [server]

     

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       # Address to bind tcp/udp to.

     

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       address = "127.0.0.1"

     

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       # Port to bind tcp/udp to.

     

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       port = 2053

     

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       # Location of root hints file.

     

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       root_hints_file = "/etc/dns/root.hints"

     

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       [logging]

     

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       # Logging output: "stdout" or "file".

     

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       output = "stdout"

     

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       # This is used only if logging.output is "file".

     

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       file_path = "/home/blu/git/kiri/alky/log"

     

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       [advanced]

     

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       # Timeout (in milliseconds) for outgoing queries before being cancelled.

     

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       query_timeout = 100

go.mod

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       module code.kiri.systems/kiri/alky

     

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       go 1.22.5

     

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       require (

     

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       	code.kiri.systems/kiri/magna v0.0.0-20240721214902-8d0a079dbd84

     

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       	github.com/BurntSushi/toml v1.4.0

     

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       )

+12

go.sum

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       code.kiri.systems/kiri/magna v0.0.0-20240721214902-8d0a079dbd84 h1:igzBX4k3REg0WZExjGLWW7/wu/X+U6QlbMc8aeO2030=

     

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       code.kiri.systems/kiri/magna v0.0.0-20240721214902-8d0a079dbd84/go.mod h1:gSzCiTKyKlUEjGgl/qTb8rxF0QUVuWOEORAsTXA0qyI=

     

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       github.com/BurntSushi/toml v1.4.0 h1:kuoIxZQy2WRRk1pttg9asf+WVv6tWQuBNVmK8+nqPr0=

     

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       github.com/BurntSushi/toml v1.4.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=

     

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       github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=

     

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       github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

     

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       github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

     

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       github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=

     

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       github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=

     

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       github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=

     

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       gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

     

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       gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

+62

main.go

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       package main

     

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       import (

     

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       	"log"

     

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       	"log/slog"

     

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       	"os"

     

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         "flag"

     

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       	"code.kiri.systems/kiri/alky/pkg/config"

     

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       	"code.kiri.systems/kiri/alky/pkg/dns"

     

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       	"code.kiri.systems/kiri/alky/pkg/rootservers"

     

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       )

     

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       var configFlag string

     

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       func init() {

     

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         flag.StringVar(&configFlag, "config", "/etc/alky/alky.toml", "config file path for alky")

     

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         flag.Parse()

     

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       }

     

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       func main() {

     

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       	cfg, err := config.LoadConfig(configFlag)

     

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       	if err != nil {

     

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       		log.Fatal(err)

     

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       	}

     

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       	rootServers, err := rootservers.DecodeRootHints(cfg.Server.RootHintsFile)

     

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       	if err != nil {

     

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       		log.Fatal(err)

     

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       	}

     

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       	var logger *slog.Logger

     

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       	switch cfg.Logging.Output {

     

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       	case "file":

     

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       		f, err := os.OpenFile(cfg.Logging.FilePath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o644)

     

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       		if err != nil {

     

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       			log.Fatal(err)

     

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       		}

     

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       		logger = slog.New(slog.NewJSONHandler(f, nil))

     

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       	case "stdout":

     

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       		fallthrough

     

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       	default:

     

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       		logger = slog.New(slog.NewJSONHandler(os.Stdout, nil))

     

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       	}

     

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       	s := dns.Server{

     

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       		Address:     cfg.Server.Address,

     

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       		Port:        cfg.Server.Port,

     

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       		Timeout:     cfg.Advanced.QueryTimeout,

     

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       		RootServers: rootServers,

     

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       		Logger: logger,

     

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       	}

     

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       	go s.TCPListenAndServe()

     

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       	go s.UDPListenAndServe()

     

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       	for {

     

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       	}

     

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       }

+57

pkg/config/config.go

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       package config

     

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       import (

     

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       	"fmt"

     

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       	"github.com/BurntSushi/toml"

     

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       )

     

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       type ServerConfig struct {

     

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       	Address       string `toml:"address"`

     

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       	Port          int    `toml:"port"`

     

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       	RootHintsFile string `toml:"root_hints_file"`

     

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       }

     

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       type LoggingConfig struct {

     

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       	Output   string `toml:"output"`

     

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       	FilePath string `toml:"file_path"`

     

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       }

     

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       type AdvancedConfig struct {

     

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       	QueryTimeout int `toml:"query_timeout"`

     

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       }

     

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       type Config struct {

     

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       	Server   ServerConfig   `toml:"server"`

     

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       	Logging  LoggingConfig  `toml:"logging"`

     

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       	Advanced AdvancedConfig `toml:"advanced"`

     

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       }

     

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       func LoadConfig(path string) (Config, error) {

     

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       	cfg := Config{}

     

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       	if _, err := toml.DecodeFile(path, &cfg); err != nil {

     

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       		return cfg, err

     

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       	}

     

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       	if cfg.Server.Address == "" {

     

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       		cfg.Server.Address = "127.0.0.1"

     

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       	}

     

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       	if cfg.Server.Port == 0 {

     

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       		cfg.Server.Port = 53

     

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       	}

     

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       	if cfg.Server.RootHintsFile == "" {

     

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       		cfg.Server.RootHintsFile = "/etc/dns/root.hints"

     

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       	}

     

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       	if cfg.Logging.Output == "file" && cfg.Logging.FilePath == "" {

     

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       		return cfg, fmt.Errorf("If `[logging.output]` is `file` then `file_path` must be set.")

     

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       	}

     

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       	if cfg.Advanced.QueryTimeout == 0 {

     

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       		cfg.Advanced.QueryTimeout = 100

     

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       	}

     

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       	return cfg, nil

     

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       }

+301

pkg/dns/dns.go

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       package dns

     

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       import (

     

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       	"context"

     

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       	"encoding/binary"

     

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       	"fmt"

     

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       	"io"

     

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       	"log/slog"

     

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       	"math/rand/v2"

     

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       	"net"

     

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       	"time"

     

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       	"code.kiri.systems/kiri/magna"

     

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       )

     

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       type Server struct {

     

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       	Address     string

     

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       	Port        int

     

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       	Timeout     int

     

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       	RootServers []string

     

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       	Logger *slog.Logger

     

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       }

     

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       type queryResponse struct {

     

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       	MSG    magna.Message

     

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       	Server string

     

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       	Error  error

     

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       }

     

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       func (s *Server) UDPListenAndServe() error {

     

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       	addr := net.UDPAddr{

     

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       		Port: s.Port,

     

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       		IP:   net.ParseIP(s.Address),

     

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       	}

     

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       	server, err := net.ListenUDP("udp", &addr)

     

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       	if err != nil {

     

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       		return err

     

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       	}

     

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       	defer server.Close()

     

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       	for {

     

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       		b := make([]byte, 512)

     

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       		_, remote_addr, err := server.ReadFromUDP(b)

     

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       		if err != nil {

     

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       			s.Logger.Warn(err.Error())

     

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       			continue

     

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       		}

     

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           start := time.Now()

     

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       		msg := s.processQuery(b)

     

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       		s.Logger.Info("query", "class", msg.Question[0].QClass.String(), "type", msg.Question[0].QType.String(), "name", msg.Question[0].QName, "rcode", msg.Header.RCode.String(), "remote_addr", remote_addr.IP, "time_taken", time.Since(start).Nanoseconds())

     

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       		if err != nil {

     

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       			s.Logger.Warn(err.Error())

     

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       			continue

     

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       		}

     

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       		ans := msg.Encode()

     

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       		// xxx: set the TC bit if the message is over 512 bytes

     

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       		if len(ans) > 512 {

     

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       			ans[3] |= 1 << 6

     

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       		}

     

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       +
       

     

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       		if _, err := server.WriteToUDP(ans, remote_addr); err != nil {

     

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       			s.Logger.Warn("sending response", "err", err.Error())

     

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       		}

     

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       	}

     

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       +
       }

     

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       +
       

     

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       func (s *Server) TCPListenAndServe() error {

     

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       	addr := net.TCPAddr{

     

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       		Port: s.Port,

     

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       		IP:   net.ParseIP(s.Address),

     

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       	}

     

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       +
       

     

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       	server, err := net.ListenTCP("tcp", &addr)

     

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       	if err != nil {

     

       78
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       		return err

     

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       	}

     

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       	defer server.Close()

     

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       +
       

     

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       	for {

     

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       		conn, err := server.Accept()

     

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       +
       		if err != nil {

     

       85
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       			s.Logger.Warn("conn error:", err)

     

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       +
       			continue

     

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       +
       		}

     

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       +
       

     

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       		sizeBuffer := make([]byte, 2)

     

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       		if _, err := io.ReadFull(conn, sizeBuffer); err != nil {

     

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       			s.Logger.Warn("tcp-error", err)

     

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       			continue

     

       93
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       +
       		}

     

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       +
       

     

       95
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       +
       		size := binary.BigEndian.Uint16(sizeBuffer)

     

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       +
       

     

       97
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       		data := make([]byte, size)

     

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       +
       		if _, err := io.ReadFull(conn, data); err != nil {

     

       99
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       			s.Logger.Warn("tcp-error", err)

     

       100
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       +
       			continue

     

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       +
       		}

     

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       +
       

     

       103
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           start := time.Now()

     

       104
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       		msg := s.processQuery(data)

     

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       		s.Logger.Info("query", "class", msg.Question[0].QClass.String(), "type", msg.Question[0].QType.String(), "name", msg.Question[0].QName, "rcode", msg.Header.RCode.String(), "remote_addr", conn.RemoteAddr(), "time_taken", time.Since(start).Nanoseconds())

     

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       +
       

     

       107
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       		ans := msg.Encode()

     

       108
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       +
       		conn.Write(binary.BigEndian.AppendUint16([]byte{}, uint16(len(ans))))

     

       109
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       +
       		if _, err := conn.Write(ans); err != nil {

     

       110
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       			s.Logger.Error("tcp-error", err)

     

       111
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       +
       		}

     

       112
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       +
       	}

     

       113
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       +
       }

     

       114
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       +
       

     

       115
       115
       +
       func (s *Server) processQuery(messageBuffer []byte) (msg magna.Message) {

     

       116
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       +
       	var query magna.Message

     

       117
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       +
       	if err := query.Decode(messageBuffer); err != nil {

     

       118
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       		slog.Warn("decode", err)

     

       119
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       		return

     

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       +
       	}

     

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       122
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       +
       	msg = magna.Message{

     

       123
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       		Header: magna.Header{

     

       124
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       +
       			ID:      query.Header.ID,

     

       125
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       +
       			QR:      true,

     

       126
       126
       +
       			OPCode:  0,

     

       127
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       +
       			AA:      false,

     

       128
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       +
       			TC:      false,

     

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       +
       			RD:      query.Header.RD,

     

       130
       130
       +
       			RA:      true,

     

       131
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       +
       			Z:       0,

     

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       +
       			RCode:   magna.NOERROR,

     

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       +
       			QDCount: 1,

     

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       +
       			ANCount: 0,

     

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       +
       			NSCount: 0,

     

       136
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       +
       			ARCount: 0,

     

       137
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       +
       		},

     

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       +
       		Question:   []magna.Question{},

     

       139
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       +
       		Answer:     []magna.ResourceRecord{},

     

       140
       140
       +
       		Additional: []magna.ResourceRecord{},

     

       141
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       +
       		Authority:  []magna.ResourceRecord{},

     

       142
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       +
       	}

     

       143
       143
       +
       

     

       144
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       +
       	if len(query.Question) < 0 {

     

       145
       145
       +
       		msg.Header.RCode = magna.FORMERR

     

       146
       146
       +
       		return

     

       147
       147
       +
       	}

     

       148
       148
       +
       	question := query.Question[0]

     

       149
       149
       +
       	msg.Question = append(msg.Question, question)

     

       150
       150
       +
       

     

       151
       151
       +
       	if question.QClass != magna.IN {

     

       152
       152
       +
       		msg.Header.RCode = magna.NOTIMP

     

       153
       153
       +
       		return

     

       154
       154
       +
       	} else {

     

       155
       155
       +
       		answer, err := s.resolveQuestion(question, s.RootServers)

     

       156
       156
       +
       		if err != nil {

     

       157
       157
       +
       			slog.Warn("resolve-question", err)

     

       158
       158
       +
       			msg.Header.RCode = magna.SERVFAIL

     

       159
       159
       +
       			return

     

       160
       160
       +
       		}

     

       161
       161
       +
       

     

       162
       162
       +
       		msg.Header.ANCount = uint16(len(answer))

     

       163
       163
       +
       		msg.Answer = answer

     

       164
       164
       +
       

     

       165
       165
       +
       		if msg.Header.ANCount == 0 {

     

       166
       166
       +
       			msg.Header.RCode = magna.NXDOMAIN

     

       167
       167
       +
       			return

     

       168
       168
       +
       		}

     

       169
       169
       +
       	}

     

       170
       170
       +
       

     

       171
       171
       +
       	return

     

       172
       172
       +
       }

     

       173
       173
       +
       

     

       174
       174
       +
       func (s *Server) resolveQuestion(question magna.Question, servers []string) ([]magna.ResourceRecord, error) {

     

       175
       175
       +
       	ctx, cancel := context.WithCancel(context.Background())

     

       176
       176
       +
       	defer cancel()

     

       177
       177
       +
       

     

       178
       178
       +
       	ch := make(chan queryResponse, len(servers))

     

       179
       179
       +
       

     

       180
       180
       +
       	for _, s := range servers {

     

       181
       181
       +
       		go queryServer(ctx, question, s, ch)

     

       182
       182
       +
       	}

     

       183
       183
       +
       

     

       184
       184
       +
       	for i := 0; i < len(servers); i++ {

     

       185
       185
       +
       		select {

     

       186
       186
       +
       		case res := <-ch:

     

       187
       187
       +
       			if res.Error != nil {

     

       188
       188
       +
       				slog.Warn("error", "question", question, "server", res.Server, "error", res.Error)

     

       189
       189
       +
       				break

     

       190
       190
       +
       			}

     

       191
       191
       +
       

     

       192
       192
       +
       			msg := res.MSG

     

       193
       193
       +
       			if msg.Header.ANCount > 0 {

     

       194
       194
       +
       				if msg.Answer[0].RType == magna.CNAMEType {

     

       195
       195
       +
       					cname_answers, err := s.resolveQuestion(magna.Question{QName: msg.Answer[0].RData.String(), QType: question.QType, QClass: question.QClass}, s.RootServers)

     

       196
       196
       +
       					if err != nil {

     

       197
       197
       +
       						slog.Warn("error with cname request", err)

     

       198
       198
       +
       						continue

     

       199
       199
       +
       					}

     

       200
       200
       +
       					msg.Answer = append(msg.Answer, cname_answers...)

     

       201
       201
       +
       				}

     

       202
       202
       +
       

     

       203
       203
       +
       				return msg.Answer, nil

     

       204
       204
       +
       			}

     

       205
       205
       +
       

     

       206
       206
       +
       			if msg.Header.ARCount > 0 {

     

       207
       207
       +
       				var nextZone []string

     

       208
       208
       +
       				for _, ans := range msg.Additional {

     

       209
       209
       +
       					if ans.RType == magna.AType {

     

       210
       210
       +
       						nextZone = append(nextZone, ans.RData.String())

     

       211
       211
       +
       					}

     

       212
       212
       +
       				}

     

       213
       213
       +
       

     

       214
       214
       +
       				return s.resolveQuestion(question, nextZone)

     

       215
       215
       +
       			}

     

       216
       216
       +
       

     

       217
       217
       +
       			if msg.Header.NSCount > 0 {

     

       218
       218
       +
       				var ns []string

     

       219
       219
       +
       				for _, a := range msg.Authority {

     

       220
       220
       +
       					if a.RType == magna.NSType {

     

       221
       221
       +
       						ans, err := s.resolveQuestion(magna.Question{QName: a.RData.String(), QType: magna.AType, QClass: magna.IN}, s.RootServers)

     

       222
       222
       +
       						if err != nil {

     

       223
       223
       +
       							slog.Warn("error with ns request", err)

     

       224
       224
       +
       							break

     

       225
       225
       +
       						}

     

       226
       226
       +
       						for _, x := range ans {

     

       227
       227
       +
       							ns = append(ns, x.RData.String())

     

       228
       228
       +
       						}

     

       229
       229
       +
       					}

     

       230
       230
       +
       				}

     

       231
       231
       +
       

     

       232
       232
       +
       				return s.resolveQuestion(question, ns)

     

       233
       233
       +
       			}

     

       234
       234
       +
       

     

       235
       235
       +
       			return []magna.ResourceRecord{}, nil

     

       236
       236
       +
       		case <-time.After(time.Duration(s.Timeout) * time.Millisecond):

     

       237
       237
       +
       			cancel()

     

       238
       238
       +
       		}

     

       239
       239
       +
       	}

     

       240
       240
       +
       

     

       241
       241
       +
       	return []magna.ResourceRecord{}, nil

     

       242
       242
       +
       }

     

       243
       243
       +
       

     

       244
       244
       +
       func queryServer(ctx context.Context, question magna.Question, server string, ch chan<- queryResponse) {

     

       245
       245
       +
         done := make(chan struct{}, 1)

     

       246
       246
       +
       

     

       247
       247
       +
         go func() {

     

       248
       248
       +
           conn, err := net.Dial("udp", fmt.Sprintf("%s:53", server))

     

       249
       249
       +
           if err != nil {

     

       250
       250
       +
             ch <- queryResponse{Error: err}

     

       251
       251
       +
             return

     

       252
       252
       +
           }

     

       253
       253
       +
           defer conn.Close()

     

       254
       254
       +
       

     

       255
       255
       +
           query := magna.Message{

     

       256
       256
       +
             Header: magna.Header{

     

       257
       257
       +
               ID:      uint16(rand.Int() % 65535),

     

       258
       258
       +
               QR:      false,

     

       259
       259
       +
               OPCode:  0,

     

       260
       260
       +
               AA:      false,

     

       261
       261
       +
               TC:      false,

     

       262
       262
       +
               RD:      false,

     

       263
       263
       +
               RA:      false,

     

       264
       264
       +
               Z:       0,

     

       265
       265
       +
               RCode:   magna.NOERROR,

     

       266
       266
       +
               QDCount: 1,

     

       267
       267
       +
               ARCount: 0,

     

       268
       268
       +
               NSCount: 0,

     

       269
       269
       +
               ANCount: 0,

     

       270
       270
       +
             },

     

       271
       271
       +
             Question: []magna.Question{question},

     

       272
       272
       +
           }

     

       273
       273
       +
           if _, err := conn.Write(query.Encode()); err != nil {

     

       274
       274
       +
             ch <- queryResponse{Server: server, Error: err}

     

       275
       275
       +
             return

     

       276
       276
       +
           }

     

       277
       277
       +
       

     

       278
       278
       +
           p := make([]byte, 512)

     

       279
       279
       +
           nn, err := conn.Read(p)

     

       280
       280
       +
       

     

       281
       281
       +
           // TODO: retry request with TCP

     

       282
       282
       +
           if err != nil || nn > 512 {

     

       283
       283
       +
             if err == nil {

     

       284
       284
       +
               err = fmt.Errorf("truncated response")

     

       285
       285
       +
             }

     

       286
       286
       +
             ch <- queryResponse{Server: server, Error: err}

     

       287
       287
       +
             return

     

       288
       288
       +
           }

     

       289
       289
       +
       

     

       290
       290
       +
           var response magna.Message

     

       291
       291
       +
           err = response.Decode(p)

     

       292
       292
       +
           ch <- queryResponse{MSG: response, Server: server, Error: err}

     

       293
       293
       +
         }()

     

       294
       294
       +
       

     

       295
       295
       +
         select {

     

       296
       296
       +
         case <-ctx.Done():

     

       297
       297
       +
           ch <- queryResponse{Server: server, Error: ctx.Err()}

     

       298
       298
       +
         case <-done:

     

       299
       299
       +
           // goroutine finished with no cancellation

     

       300
       300
       +
         }

     

       301
       301
       +
       }

+41

pkg/rootservers/loader.go

···

       1
       1
       +
       package rootservers

     

       2
       2
       +
       

     

       3
       3
       +
       import (

     

       4
       4
       +
       	"bytes"

     

       5
       5
       +
       	"net"

     

       6
       6
       +
       	"os"

     

       7
       7
       +
       )

     

       8
       8
       +
       

     

       9
       9
       +
       // should probally just be a part of magna

     

       10
       10
       +
       func DecodeRootHints(path string) ([]string, error) {

     

       11
       11
       +
       	rootServers := make([]string, 0)

     

       12
       12
       +
       

     

       13
       13
       +
       	data, err := os.ReadFile(path)

     

       14
       14
       +
       	if err != nil {

     

       15
       15
       +
       		return rootServers, err

     

       16
       16
       +
       	}

     

       17
       17
       +
       

     

       18
       18
       +
       	for _, line := range bytes.Split(data, []byte{'\n'}) {

     

       19
       19
       +
       		// skip comments

     

       20
       20
       +
       		if line[0] == ';' {

     

       21
       21
       +
       			continue

     

       22
       22
       +
       		}

     

       23
       23
       +
       

     

       24
       24
       +
       		// xxx: not a great way to do this should probally just be a zone

     

       25
       25
       +
       		//      custom parser

     

       26
       26
       +
       		fields := bytes.Fields(line)

     

       27
       27
       +
       		if len(fields) != 4 {

     

       28
       28
       +
       			continue

     

       29
       29
       +
       		}

     

       30
       30
       +
       

     

       31
       31
       +
       		// only supports ipv4 for now, need to do testing with ipv6 and support

     

       32
       32
       +
       		// https://datatracker.ietf.org/doc/html/rfc3596 in magna

     

       33
       33
       +
       		if bytes.Equal(fields[2], []byte{'A'}) {

     

       34
       34
       +
       			if address := net.ParseIP(string(fields[3])); address != nil {

     

       35
       35
       +
       				rootServers = append(rootServers, address.String())

     

       36
       36
       +
       			}

     

       37
       37
       +
       		}

     

       38
       38
       +
       	}

     

       39
       39
       +
       

     

       40
       40
       +
       	return rootServers, nil

     

       41
       41
       +
       }