Support old conntrack stats

Linux < 2.6.35 was missing the `search_restart` field in nf_conntrack.
* Refactor stat parsing to simplify code.
* Support 16-field nf_conntrack entries.
* Support additional fields.

Fixes: #499

Signed-off-by: SuperQ <superq@gmail.com>

internal/util/parse.go

@@ -64,6 +64,21 @@ func ParsePInt64s(ss []string) ([]*int64, error) {
 	return us, nil
 }
 
+// Parses a uint64 from given hex in string.
+func ParseHexUint64s(ss []string) ([]*uint64, error) {
+	us := make([]*uint64, 0, len(ss))
+	for _, s := range ss {
+		u, err := strconv.ParseUint(s, 16, 64)
+		if err != nil {
+			return nil, err
+		}
+
+		us = append(us, &u)
+	}
+
+	return us, nil
+}
+
 // ReadUintFromFile reads a file and attempts to parse a uint64 from it.
 func ReadUintFromFile(path string) (uint64, error) {
 	data, err := os.ReadFile(path)

net_conntrackstat.go

@@ -18,7 +18,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"strconv"
 	"strings"
 
 	"github.com/prometheus/procfs/internal/util"
@@ -28,9 +27,13 @@ import (
 // and contains netfilter conntrack statistics at one CPU core.
 type ConntrackStatEntry struct {
 	Entries       uint64
+	Searched      uint64
 	Found         uint64
+	New           uint64
 	Invalid       uint64
 	Ignore        uint64
+	Delete        uint64
+	DeleteList    uint64
 	Insert        uint64
 	InsertFailed  uint64
 	Drop          uint64
@@ -81,73 +84,34 @@ func parseConntrackStat(r io.Reader) ([]ConntrackStatEntry, error) {
 
 // Parses a ConntrackStatEntry from given array of fields.
 func parseConntrackStatEntry(fields []string) (*ConntrackStatEntry, error) {
-	if len(fields) != 17 {
-		return nil, fmt.Errorf("invalid conntrackstat entry, missing fields")
-	}
-	entry := &ConntrackStatEntry{}
-
-	entries, err := parseConntrackStatField(fields[0])
-	if err != nil {
-		return nil, err
-	}
-	entry.Entries = entries
-
-	found, err := parseConntrackStatField(fields[2])
-	if err != nil {
-		return nil, err
-	}
-	entry.Found = found
-
-	invalid, err := parseConntrackStatField(fields[4])
-	if err != nil {
-		return nil, err
-	}
-	entry.Invalid = invalid
-
-	ignore, err := parseConntrackStatField(fields[5])
-	if err != nil {
-		return nil, err
-	}
-	entry.Ignore = ignore
-
-	insert, err := parseConntrackStatField(fields[8])
+	entries, err := util.ParseHexUint64s(fields)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("invalid conntrackstat entry, couldn't parse fields: %s", err)
 	}
-	entry.Insert = insert
-
-	insertFailed, err := parseConntrackStatField(fields[9])
-	if err != nil {
-		return nil, err
+	numEntries := len(entries)
+	if numEntries < 16 || numEntries > 17 {
+		return nil, fmt.Errorf("invalid conntrackstat entry, invalid number of fields: %d", numEntries)
 	}
-	entry.InsertFailed = insertFailed
 
-	drop, err := parseConntrackStatField(fields[10])
-	if err != nil {
-		return nil, err
+	stats := &ConntrackStatEntry{
+		Entries:      *entries[0],
+		Searched:     *entries[1],
+		Found:        *entries[2],
+		New:          *entries[3],
+		Invalid:      *entries[4],
+		Ignore:       *entries[5],
+		Delete:       *entries[6],
+		DeleteList:   *entries[7],
+		Insert:       *entries[8],
+		InsertFailed: *entries[9],
+		Drop:         *entries[10],
+		EarlyDrop:    *entries[11],
 	}
-	entry.Drop = drop
 
-	earlyDrop, err := parseConntrackStatField(fields[11])
-	if err != nil {
-		return nil, err
+	// Ignore missing search_restart on Linux < 2.6.35.
+	if numEntries == 17 {
+		stats.SearchRestart = *entries[16]
 	}
-	entry.EarlyDrop = earlyDrop
 
-	searchRestart, err := parseConntrackStatField(fields[16])
-	if err != nil {
-		return nil, err
-	}
-	entry.SearchRestart = searchRestart
-
-	return entry, nil
-}
-
-// Parses a uint64 from given hex in string.
-func parseConntrackStatField(field string) (uint64, error) {
-	val, err := strconv.ParseUint(field, 16, 64)
-	if err != nil {
-		return 0, fmt.Errorf("couldn't parse %q field: %w", field, err)
-	}
-	return val, err
+	return stats, nil
 }

net_conntrackstat_test.go

@@ -83,3 +83,36 @@ func TestParseConntrackStat(t *testing.T) {
 		t.Errorf("want %v, have %v", want, have)
 	}
 }
+
+func TestParseOldConntrackStat(t *testing.T) {
+	var nfConntrackStat = []byte(`entries  searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error  expect_new expect_create expect_delete
+0000002b  0003159f 02e6786a 00142562 0001bf93 00e1a051 00142537 000b8fe0 000b900b 00000000 00000000 00000000 0001b46a  00000000 00000000 00000000
+`)
+	r := bytes.NewReader(nfConntrackStat)
+
+	have, err := parseConntrackStat(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := []ConntrackStatEntry{
+		ConntrackStatEntry{
+			Entries:       43,
+			Searched:      202143,
+			Found:         48658538,
+			New:           1320290,
+			Invalid:       114579,
+			Ignore:        14786641,
+			Delete:        1320247,
+			DeleteList:    757728,
+			Insert:        757771,
+			InsertFailed:  0,
+			Drop:          0,
+			EarlyDrop:     0,
+			SearchRestart: 0,
+		},
+	}
+	if !reflect.DeepEqual(want, have) {
+		t.Errorf("want %v, have %v", want, have)
+	}
+}