add plugin system

hosts/hosts.go

@@ -12,6 +12,7 @@ import (
 	"github.com/go-gost/core/hosts"
 	"github.com/go-gost/core/logger"
 	"github.com/go-gost/x/internal/loader"
+	"google.golang.org/grpc"
 )
 
 type Mapping struct {
@@ -24,6 +25,7 @@ type options struct {
 	fileLoader  loader.Loader
 	redisLoader loader.Loader
 	httpLoader  loader.Loader
+	client      *grpc.ClientConn
 	period      time.Duration
 	logger      logger.Logger
 }
@@ -60,6 +62,12 @@ func HTTPLoaderOption(httpLoader loader.Loader) Option {
 	}
 }
 
+func PluginConnOption(c *grpc.ClientConn) Option {
+	return func(opts *options) {
+		opts.client = c
+	}
+}
+
 func LoggerOption(logger logger.Logger) Option {
 	return func(opts *options) {
 		opts.logger = logger
@@ -104,7 +112,7 @@ func NewHostMapper(opts ...Option) hosts.HostMapper {
 // Lookup searches the IP address corresponds to the given network and host from the host table.
 // The network should be 'ip', 'ip4' or 'ip6', default network is 'ip'.
 // the host should be a hostname (example.org) or a hostname with dot prefix (.example.org).
-func (h *hostMapper) Lookup(network, host string) (ips []net.IP, ok bool) {
+func (h *hostMapper) Lookup(ctx context.Context, network, host string) (ips []net.IP, ok bool) {
 	h.options.logger.Debugf("lookup %s/%s", host, network)
 	ips = h.lookup(host)
 	if ips == nil {

hosts/plugin.go

@@ -0,0 +1,66 @@
+package hosts
+
+import (
+	"context"
+	"net"
+
+	"github.com/go-gost/core/hosts"
+	"github.com/go-gost/plugin/hosts/proto"
+	xlogger "github.com/go-gost/x/logger"
+)
+
+type pluginHostMapper struct {
+	client  proto.HostMapperClient
+	options options
+}
+
+// NewPluginHostMapper creates a plugin HostMapper.
+func NewPluginHostMapper(opts ...Option) hosts.HostMapper {
+	var options options
+	for _, opt := range opts {
+		opt(&options)
+	}
+	if options.logger == nil {
+		options.logger = xlogger.Nop()
+	}
+
+	p := &pluginHostMapper{
+		options: options,
+	}
+	if options.client != nil {
+		p.client = proto.NewHostMapperClient(options.client)
+	}
+	return p
+}
+
+func (p *pluginHostMapper) Lookup(ctx context.Context, network, host string) (ips []net.IP, ok bool) {
+	p.options.logger.Debugf("lookup %s/%s", host, network)
+
+	if p.client == nil {
+		return
+	}
+
+	r, err := p.client.Lookup(ctx,
+		&proto.LookupRequest{
+			Network: network,
+			Host:    host,
+		})
+	if err != nil {
+		p.options.logger.Error(err)
+		return
+	}
+	for _, s := range r.Ips {
+		if ip := net.ParseIP(s); ip != nil {
+			ips = append(ips, ip)
+		}
+	}
+	ok = r.Ok
+	return
+}
+
+func (p *pluginHostMapper) Close() error {
+	if p.options.client != nil {
+		return p.options.client.Close()
+	}
+	return nil
+}