Handle repeated NNTP command whitespace

internal/news/nntpd/server.go

@@ -142,12 +142,16 @@ func (s *Server) Process(nc net.Conn) {
 		if err != nil {
 			return
 		}
-		cmd := strings.Split(l, " ")
-		args := []string{}
-		if len(cmd) > 1 {
-			args = cmd[1:]
+		fields := strings.Fields(l)
+		if len(fields) == 0 {
+			err = handleDefault(nil, sess, c)
+		} else {
+			args := []string{}
+			if len(fields) > 1 {
+				args = fields[1:]
+			}
+			err = sess.dispatchCommand(fields[0], args, c)
 		}
-		err = sess.dispatchCommand(cmd[0], args, c)
 		if err != nil {
 			if _, isNNTPError := err.(*NNTPError); err == io.EOF {
 				return

internal/news/nntpd/server_test.go

@@ -0,0 +1,87 @@
+package nntpd
+
+import (
+	"errors"
+	"net"
+	"net/textproto"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/dustin/go-nntp"
+)
+
+type whitespaceBackend struct {
+	group *nntp.Group
+}
+
+func (b *whitespaceBackend) ListGroups(max int) ([]*nntp.Group, error) {
+	return []*nntp.Group{b.group}, nil
+}
+
+func (b *whitespaceBackend) GetGroup(name string) (*nntp.Group, error) {
+	if name == b.group.Name {
+		return b.group, nil
+	}
+	return nil, ErrNoSuchGroup
+}
+
+func (b *whitespaceBackend) GetArticle(group *nntp.Group, id string) (*nntp.Article, error) {
+	return nil, ErrInvalidArticleNumber
+}
+
+func (b *whitespaceBackend) GetArticles(group *nntp.Group, from, to int64) ([]NumberedArticle, error) {
+	return nil, nil
+}
+
+func (b *whitespaceBackend) Authorized() bool { return true }
+
+func (b *whitespaceBackend) Authenticate(user, pass string) (Backend, error) {
+	return b, nil
+}
+
+func (b *whitespaceBackend) AllowPost() bool { return false }
+
+func (b *whitespaceBackend) Post(article *nntp.Article) error {
+	return errors.New("posting disabled")
+}
+
+func TestProcessCollapsesRepeatedCommandWhitespace(t *testing.T) {
+	backend := &whitespaceBackend{
+		group: &nntp.Group{Name: "pfs.general", Count: 1, Low: 1, High: 1, Posting: nntp.PostingPermitted},
+	}
+	server := NewServer(backend)
+	clientConn, serverConn := net.Pipe()
+	defer clientConn.Close()
+
+	done := make(chan struct{})
+	go func() {
+		server.Process(serverConn)
+		close(done)
+	}()
+
+	client := textproto.NewConn(clientConn)
+	defer client.Close()
+
+	if line, err := client.ReadLine(); err != nil || !strings.HasPrefix(line, "200 ") {
+		t.Fatalf("greeting = %q, %v", line, err)
+	}
+	if err := client.PrintfLine("GROUP  pfs.general"); err != nil {
+		t.Fatalf("send GROUP: %v", err)
+	}
+	if line, err := client.ReadLine(); err != nil || !strings.HasPrefix(line, "211 ") {
+		t.Fatalf("GROUP with repeated spaces = %q, %v; want 211", line, err)
+	}
+	if err := client.PrintfLine("QUIT"); err != nil {
+		t.Fatalf("send QUIT: %v", err)
+	}
+	if line, err := client.ReadLine(); err != nil || !strings.HasPrefix(line, "205 ") {
+		t.Fatalf("QUIT = %q, %v; want 205", line, err)
+	}
+
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("server did not close after QUIT")
+	}
+}