Commit

diff --git a/README.md b/README.md
index 4b43d3427f8fb6649b905350a1c2deddbce6ed93..ac50bdeb6d82053985e5ff082149ea3c9c8ca1cd 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ | BODY              | READER        | 🗸           | RFC3977  |
 | DATE              | READER        | 🗸           | RFC3977  |
 | GROUP             | READER        | 🗸           | RFC3977  |
 | LAST              | READER        | ☓           | RFC3977  |
-| LISTGROUP         | READER        | ☓           | RFC3977  |
+| LISTGROUP         | READER        | 🗸           | RFC3977  |
 | NEWGROUPS         | READER        | ☓           | RFC3977  |
 | NEXT              | READER        | ☓           | RFC3977  |
 
diff --git a/reader.go b/reader.go
index 92ff81210e4ce2100c498569010a2192004a5692..792d22535ed1034a6c8392626454c033c5c1bf74 100644
--- a/reader.go
+++ b/reader.go
@@ -3,6 +3,7 @@
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"time"
 )
 
@@ -99,3 +100,52 @@ 	default:
 		return ErrUnexpectedResponse
 	}
 }
+
+func (c *Conn) ListGroup(ctx context.Context, group string, from uint64, to uint64) ([]uint64, error) {
+	if c.caps&CapReader == 0 {
+		return nil, ErrCapabilityNotSupported
+	}
+
+	var param string
+	if group != "" {
+		param += " " + group
+		if from != 0 && to != 0 {
+			param += fmt.Sprintf(" %d-%d", from, to)
+		}
+	}
+
+	resp, err := c.Cmd(ctx, "LISTGROUP"+param)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list content of group '%s': %w", group, err)
+	}
+
+	var parsedList []uint64
+	var numbuf []byte
+	var num uint64
+	for _, bte := range resp.Body {
+		if bte >= 0x30 && bte < 0x3A {
+			numbuf = append(numbuf, bte)
+			continue
+		}
+		if len(numbuf) == 0 {
+			continue
+		}
+		num, err = strconv.ParseUint(string(numbuf), 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse response: %w", err)
+		}
+		parsedList = append(parsedList, num)
+		numbuf = []byte{}
+	}
+
+	switch resp.Status.Code {
+	case StatusArticleNumbersFollow:
+		return parsedList, nil
+	case StatusNoSuchNewsgroup:
+		return nil, ErrNoSuchNewsgroup
+	case StatusNoNewsgroupSelected:
+		return nil, ErrNoNewsgroupSelected
+	default:
+		return nil, ErrUnexpectedResponse
+	}
+}
diff --git a/reader_test.go b/reader_test.go
index 15a138a691d1141d8276ba0d1ac879f4a6bcd885..55404d67665056818381f74b4a64868cc090a9fa 100644
--- a/reader_test.go
+++ b/reader_test.go
@@ -1,10 +1,17 @@
 package nntp_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
 	"testing"
+	"text/scanner"
 	"time"
+
+	_ "embed"
 
 	"mpldr.codes/usenet/nntp"
 )
@@ -222,3 +229,162 @@ 			}
 		})
 	}
 }
+
+func TestListGroup(t *testing.T) {
+	if NewsServerSecure == "" || NewsServerUser == "" || NewsServerPassword == "" {
+		t.Log("secure server address, username, and password required in variables_test.go")
+		t.SkipNow()
+	}
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+	t.Parallel()
+	tests := []struct {
+		name          string
+		group         string
+		expectedError error
+		minEntries    int
+	}{
+		/*{ // eweka does not returns no newsgroup selected
+			name:          "invalid-group",
+			group:         "alt.binaries.fritzelschnitzelritzel",
+			expectedError: nntp.ErrNoSuchNewsgroup,
+		},*/
+		{
+			name:          "existing-group",
+			group:         "alt.binaries.dvdr.german",
+			expectedError: nil,
+			minEntries:    11835721,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c, err := nntp.Dial(NewsServerSecure)
+			if err != nil {
+				t.Skipf("connection to '%s' failed: %v", NewsServerSecure, err)
+			}
+			defer c.Close(context.Background())
+
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+			err = c.LoginUserPass(ctx, NewsServerUser, NewsServerPassword)
+			if err != nil {
+				t.Skipf("login failed: %v", err)
+			}
+
+			ctx, cancel = context.WithTimeout(context.Background(), 30*time.Second)
+			defer cancel()
+			list, err := c.ListGroup(ctx, test.group, 0, 0)
+			if !errors.Is(err, test.expectedError) {
+				t.Errorf("unexpected result:\n\tgot:      %v\n\texpected: %v\n", err, test.expectedError)
+			}
+			if len(list) < test.minEntries {
+				t.Errorf("less entries than expected: %d < %d", len(list), test.minEntries)
+			}
+		})
+	}
+}
+
+//go:embed testdata/ListGroupShortened
+var groupList []byte
+
+func BenchmarkListGroupListParse(b *testing.B) {
+	var parsedList1 []uint64
+	b.Run("scanner.Scanner", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var parsedList []uint64
+			var s scanner.Scanner
+			s.Init(bytes.NewReader(groupList))
+			var num uint64
+			var err error
+			for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
+				num, err = strconv.ParseUint(s.TokenText(), 10, 64)
+				if err != nil {
+					b.Fail()
+				}
+				parsedList = append(parsedList, num)
+			}
+			parsedList1 = parsedList
+		}
+	})
+
+	var parsedList2 []uint64
+	b.Run("bytes.Split", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var parsedList []uint64
+			var num uint64
+			var err error
+			for _, seq := range bytes.Split(groupList, []byte{'\r', '\n'}) {
+				if len(seq) == 0 {
+					continue
+				}
+				num, err = strconv.ParseUint(string(seq), 10, 64)
+				if err != nil {
+					fmt.Printf("%s\n%v\n%v\n", seq, seq, err)
+					b.FailNow()
+				}
+				parsedList = append(parsedList, num)
+			}
+			parsedList2 = parsedList
+		}
+	})
+
+	var parsedList3 []uint64
+	b.Run("byteslice-iter", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			var parsedList []uint64
+			var numbuf []byte
+			var num uint64
+			var err error
+			for _, bte := range groupList {
+				if bte >= 0x30 && bte < 0x3A {
+					numbuf = append(numbuf, bte)
+					continue
+				}
+				if len(numbuf) == 0 {
+					continue
+				}
+				num, err = strconv.ParseUint(string(numbuf), 10, 64)
+				if err != nil {
+					b.FailNow()
+				}
+				parsedList = append(parsedList, num)
+				numbuf = []byte{}
+			}
+			parsedList3 = parsedList
+		}
+	})
+
+	if !reflect.DeepEqual(parsedList1, parsedList2) {
+		minlen := len(parsedList1)
+		if len(parsedList1) != len(parsedList2) {
+			b.Logf("%d != %d", len(parsedList1), len(parsedList2))
+			if len(parsedList2) < minlen {
+				minlen = len(parsedList2)
+			}
+		}
+		for i := 0; i < minlen; i++ {
+			if parsedList1[i] != parsedList2[i] {
+				b.Logf("index %d: %d != %d", i, parsedList1[i], parsedList2[i])
+			}
+		}
+		b.Error("list 1 differs from list 2")
+	}
+
+	if !reflect.DeepEqual(parsedList1, parsedList3) {
+		minlen := len(parsedList1)
+		if len(parsedList1) != len(parsedList3) {
+			b.Logf("%d != %d", len(parsedList1), len(parsedList3))
+			if len(parsedList3) < minlen {
+				minlen = len(parsedList3)
+			}
+		}
+		for i := 0; i < minlen; i++ {
+			if parsedList1[i] != parsedList3[i] {
+				b.Logf("index %d: %d != %d", i, parsedList1[i], parsedList3[i])
+			}
+		}
+		b.Error("list 1 differs from list 3")
+	}
+}
diff --git a/status.go b/status.go
index 1ab9a2bcf7ce1467e8b262c3e3b0fe887ea413ed..2a9df0409a6171d16bb0452bbcd4d35803226ef6 100644
--- a/status.go
+++ b/status.go
@@ -9,6 +9,7 @@ 	StatusServiceAvailable            = 200
 	StatusServiceNoPosting            = 201
 	StatusConnectionClosing           = 205
 	StatusGroupSelected               = 211
+	StatusArticleNumbersFollow        = 211
 	StatusArticleFollows              = 220
 	StatusBodyFollows                 = 222
 	StatusHeadersFollow               = 221
diff --git a/testdata/ListGroupShortened b/testdata/ListGroupShortened
new file mode 100644
index 0000000000000000000000000000000000000000..5ac25325b8ceb15a6981b462f27cab6c4ffcac04
--- /dev/null
+++ b/testdata/ListGroupShortened
@@ -0,0 +1,140 @@
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Commit `d564bf8646f5fdd3a095a885bf5eaf5a8748fa3e`

Stats

Changeset

README.md	+1/-1
reader.go	+50/-0
reader_test.go	+166/-0
status.go	+1/-0
testdata/ListGroupShortened	+140/-0
Commit d564bf8646f5fdd3a095a885bf5eaf5a8748fa3e

Stats

Changeset

Commit `d564bf8646f5fdd3a095a885bf5eaf5a8748fa3e`
