Add support for per-interface SNMP6 stats

Signed-off-by: Felix Geschwindner <[email protected]>

Author: Vascko

README.md

@@ -47,15 +47,15 @@ However, most of the API includes unit tests which can be run with `make test`.
 The procfs library includes a set of test fixtures which include many example files from
 the `/proc` and `/sys` filesystems.  These fixtures are included as a [ttar](https://github.com/ideaship/ttar) file
 which is extracted automatically during testing.  To add/update the test fixtures, first
-ensure the `fixtures` directory is up to date by removing the existing directory and then
-extracting the ttar file using `make fixtures/.unpacked` or just `make test`.
+ensure the `testdata/fixtures` directory is up to date by removing the existing directory and then
+extracting the ttar file using `make testdata/fixtures/.unpacked` or just `make test`.
 
 ```bash
 rm -rf testdata/fixtures
 make test
 ```
 
-Next, make the required changes to the extracted files in the `fixtures` directory.  When
+Next, make the required changes to the extracted files in the `testdata/fixtures` directory.  When
 the changes are complete, run `make update_fixtures` to create a new `fixtures.ttar` file
 based on the updated `fixtures` directory.  And finally, verify the changes using
 `git diff testdata/fixtures.ttar`.

net_dev_snmp6.go

@@ -0,0 +1,96 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package procfs
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// NetDevSNMP6 is parsed from files in /proc/net/dev_snmp6/ or /proc/<PID>/net/dev_snmp6/.
+// The outer map's keys are interface names and the inner map's keys are stat names.
+//
+// If you'd like a total across all interfaces, please use the Snmp6() method of the Proc type.
+type NetDevSNMP6 map[string]map[string]uint64
+
+// Returns kernel/system statistics read from interface files within the /proc/net/dev_snmp6/
+// directory.
+func (fs FS) NetDevSNMP6() (NetDevSNMP6, error) {
+	return newNetDevSNMP6(fs.proc.Path("net/dev_snmp6"))
+}
+
+// Returns kernel/system statistics read from interface files within the /proc/<PID>/net/dev_snmp6/
+// directory.
+func (p Proc) NetDevSNMP6() (NetDevSNMP6, error) {
+	return newNetDevSNMP6(p.path("net/dev_snmp6"))
+}
+
+// newNetDevSNMP6 creates a new NetDevSNMP6 from the contents of the given directory.
+func newNetDevSNMP6(dir string) (NetDevSNMP6, error) {
+	netDevSNMP6 := make(NetDevSNMP6)
+
+	// The net/dev_snmp6 folders contain one file per interface
+	ifaceFiles, err := os.ReadDir(dir)
+	if err != nil {
+		// On systems with IPv6 disabled, this directory won't exist.
+		// Do nothing.
+		if errors.Is(err, os.ErrNotExist) {
+			return netDevSNMP6, err
+		}
+		return netDevSNMP6, err
+	}
+
+	for _, iFaceFile := range ifaceFiles {
+		f, err := os.Open(dir + "/" + iFaceFile.Name())
+		if err != nil {
+			return netDevSNMP6, err
+		}
+		defer f.Close()
+
+		netDevSNMP6[iFaceFile.Name()], err = parseNetDevSNMP6Stats(f)
+		if err != nil {
+			return netDevSNMP6, err
+		}
+	}
+
+	return netDevSNMP6, nil
+}
+
+func parseNetDevSNMP6Stats(r io.Reader) (map[string]uint64, error) {
+	m := make(map[string]uint64)
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		stat := strings.Fields(scanner.Text())
+		if len(stat) < 2 {
+			continue
+		}
+		key, val := stat[0], stat[1]
+
+		// Expect stat name to contain "6" or be "ifIndex"
+		if strings.Contains(key, "6") || key == "ifIndex" {
+			v, err := strconv.ParseUint(val, 10, 64)
+			if err != nil {
+				return m, err
+			}
+
+			m[key] = v
+		}
+	}
+	return m, scanner.Err()
+}

net_dev_snmp6_test.go

@@ -0,0 +1,86 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package procfs
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestNetDevSNMP6(t *testing.T) {
+	fs, err := NewFS(procTestFixtures)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	netDevSNMP6, err := fs.NetDevSNMP6()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := validateNetDevSNMP6(netDevSNMP6); err != nil {
+		t.Error(err.Error())
+	}
+}
+
+func TestProcNetDevSNMP6(t *testing.T) {
+	p, err := getProcFixtures(t).Proc(26231)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	procNetDevSNMP6, err := p.NetDevSNMP6()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := validateNetDevSNMP6(procNetDevSNMP6); err != nil {
+		t.Error(err.Error())
+	}
+}
+
+func validateNetDevSNMP6(have NetDevSNMP6) error {
+	var wantNetDevSNMP6 = map[string]map[string]uint64{
+		"eth0": {
+			"ifIndex":      1,
+			"Ip6InOctets":  14064059261,
+			"Ip6OutOctets": 811213622,
+			"Icmp6InMsgs":  53293,
+			"Icmp6OutMsgs": 20400,
+		},
+		"eth1": {
+			"ifIndex":      2,
+			"Ip6InOctets":  303177290674,
+			"Ip6OutOctets": 29245052746,
+			"Icmp6InMsgs":  37911,
+			"Icmp6OutMsgs": 114015,
+		},
+	}
+
+	for wantIface, wantData := range wantNetDevSNMP6 {
+		if haveData, ok := have[wantIface]; ok {
+			for wantStat, wantVal := range wantData {
+				if haveVal, ok := haveData[wantStat]; !ok {
+					return fmt.Errorf("stat %s missing from %s test data", wantStat, wantIface)
+				} else if wantVal != haveVal {
+					return fmt.Errorf("%s - %s: want %d, have %d", wantIface, wantStat, wantVal, haveVal)
+				}
+			}
+		} else {
+			return fmt.Errorf("%s not found in test data", wantIface)
+		}
+	}
+
+	return nil
+}