/
resolver.go
182 lines (153 loc) · 4.27 KB
/
resolver.go
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package resolver
import (
"context"
"errors"
"fmt"
"math/rand"
"net"
"strings"
"time"
"github.com/laof/collide/component/trie"
"github.com/miekg/dns"
)
var (
// DefaultResolver aim to resolve ip
DefaultResolver Resolver
// DisableIPv6 means don't resolve ipv6 host
// default value is true
DisableIPv6 = true
// DefaultHosts aim to resolve hosts
DefaultHosts = trie.New()
// DefaultDNSTimeout defined the default dns request timeout
DefaultDNSTimeout = time.Second * 5
)
var (
ErrIPNotFound = errors.New("couldn't find ip")
ErrIPVersion = errors.New("ip version error")
ErrIPv6Disabled = errors.New("ipv6 disabled")
)
type Resolver interface {
LookupIP(ctx context.Context, host string) ([]net.IP, error)
LookupIPv4(ctx context.Context, host string) ([]net.IP, error)
LookupIPv6(ctx context.Context, host string) ([]net.IP, error)
ResolveIP(host string) (ip net.IP, err error)
ResolveIPv4(host string) (ip net.IP, err error)
ResolveIPv6(host string) (ip net.IP, err error)
ExchangeContext(ctx context.Context, m *dns.Msg) (msg *dns.Msg, err error)
}
// LookupIPv4 with a host, return ipv4 list
func LookupIPv4(ctx context.Context, host string) ([]net.IP, error) {
if node := DefaultHosts.Search(host); node != nil {
if ip := node.Data.(net.IP).To4(); ip != nil {
return []net.IP{ip}, nil
}
}
ip := net.ParseIP(host)
if ip != nil {
if !strings.Contains(host, ":") {
return []net.IP{ip}, nil
}
return nil, ErrIPVersion
}
if DefaultResolver != nil {
return DefaultResolver.LookupIPv4(ctx, host)
}
ctx, cancel := context.WithTimeout(context.Background(), DefaultDNSTimeout)
defer cancel()
ipAddrs, err := net.DefaultResolver.LookupIP(ctx, "ip4", host)
if err != nil {
return nil, err
} else if len(ipAddrs) == 0 {
return nil, ErrIPNotFound
}
return ipAddrs, nil
}
// ResolveIPv4 with a host, return ipv4
func ResolveIPv4(host string) (net.IP, error) {
ips, err := LookupIPv4(context.Background(), host)
if err != nil {
return nil, err
} else if len(ips) == 0 {
return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
}
return ips[rand.Intn(len(ips))], nil
}
// LookupIPv6 with a host, return ipv6 list
func LookupIPv6(ctx context.Context, host string) ([]net.IP, error) {
if DisableIPv6 {
return nil, ErrIPv6Disabled
}
if node := DefaultHosts.Search(host); node != nil {
if ip := node.Data.(net.IP).To16(); ip != nil {
return []net.IP{ip}, nil
}
}
ip := net.ParseIP(host)
if ip != nil {
if strings.Contains(host, ":") {
return []net.IP{ip}, nil
}
return nil, ErrIPVersion
}
if DefaultResolver != nil {
return DefaultResolver.LookupIPv6(ctx, host)
}
ctx, cancel := context.WithTimeout(context.Background(), DefaultDNSTimeout)
defer cancel()
ipAddrs, err := net.DefaultResolver.LookupIP(ctx, "ip6", host)
if err != nil {
return nil, err
} else if len(ipAddrs) == 0 {
return nil, ErrIPNotFound
}
return ipAddrs, nil
}
// ResolveIPv6 with a host, return ipv6
func ResolveIPv6(host string) (net.IP, error) {
ips, err := LookupIPv6(context.Background(), host)
if err != nil {
return nil, err
} else if len(ips) == 0 {
return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
}
return ips[rand.Intn(len(ips))], nil
}
// LookupIPWithResolver same as ResolveIP, but with a resolver
func LookupIPWithResolver(ctx context.Context, host string, r Resolver) ([]net.IP, error) {
if node := DefaultHosts.Search(host); node != nil {
return []net.IP{node.Data.(net.IP)}, nil
}
if r != nil {
if DisableIPv6 {
return r.LookupIPv4(ctx, host)
}
return r.LookupIP(ctx, host)
} else if DisableIPv6 {
return LookupIPv4(ctx, host)
}
ip := net.ParseIP(host)
if ip != nil {
return []net.IP{ip}, nil
}
ips, err := net.DefaultResolver.LookupIP(ctx, "ip", host)
if err != nil {
return nil, err
} else if len(ips) == 0 {
return nil, ErrIPNotFound
}
return ips, nil
}
// ResolveIP with a host, return ip
func LookupIP(ctx context.Context, host string) ([]net.IP, error) {
return LookupIPWithResolver(ctx, host, DefaultResolver)
}
// ResolveIP with a host, return ip
func ResolveIP(host string) (net.IP, error) {
ips, err := LookupIP(context.Background(), host)
if err != nil {
return nil, err
} else if len(ips) == 0 {
return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
}
return ips[rand.Intn(len(ips))], nil
}