1// Copyright 2019 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package procfs
15
16import (
17	"bufio"
18	"bytes"
19	"errors"
20	"fmt"
21	"io"
22	"strings"
23
24	"github.com/prometheus/procfs/internal/util"
25)
26
27// A NetSockstat contains the output of /proc/net/sockstat{,6} for IPv4 or IPv6,
28// respectively.
29type NetSockstat struct {
30	// Used is non-nil for IPv4 sockstat results, but nil for IPv6.
31	Used      *int
32	Protocols []NetSockstatProtocol
33}
34
35// A NetSockstatProtocol contains statistics about a given socket protocol.
36// Pointer fields indicate that the value may or may not be present on any
37// given protocol.
38type NetSockstatProtocol struct {
39	Protocol string
40	InUse    int
41	Orphan   *int
42	TW       *int
43	Alloc    *int
44	Mem      *int
45	Memory   *int
46}
47
48// NetSockstat retrieves IPv4 socket statistics.
49func (fs FS) NetSockstat() (*NetSockstat, error) {
50	return readSockstat(fs.proc.Path("net", "sockstat"))
51}
52
53// NetSockstat6 retrieves IPv6 socket statistics.
54//
55// If IPv6 is disabled on this kernel, the returned error can be checked with
56// os.IsNotExist.
57func (fs FS) NetSockstat6() (*NetSockstat, error) {
58	return readSockstat(fs.proc.Path("net", "sockstat6"))
59}
60
61// readSockstat opens and parses a NetSockstat from the input file.
62func readSockstat(name string) (*NetSockstat, error) {
63	// This file is small and can be read with one syscall.
64	b, err := util.ReadFileNoStat(name)
65	if err != nil {
66		// Do not wrap this error so the caller can detect os.IsNotExist and
67		// similar conditions.
68		return nil, err
69	}
70
71	stat, err := parseSockstat(bytes.NewReader(b))
72	if err != nil {
73		return nil, fmt.Errorf("failed to read sockstats from %q: %v", name, err)
74	}
75
76	return stat, nil
77}
78
79// parseSockstat reads the contents of a sockstat file and parses a NetSockstat.
80func parseSockstat(r io.Reader) (*NetSockstat, error) {
81	var stat NetSockstat
82	s := bufio.NewScanner(r)
83	for s.Scan() {
84		// Expect a minimum of a protocol and one key/value pair.
85		fields := strings.Split(s.Text(), " ")
86		if len(fields) < 3 {
87			return nil, fmt.Errorf("malformed sockstat line: %q", s.Text())
88		}
89
90		// The remaining fields are key/value pairs.
91		kvs, err := parseSockstatKVs(fields[1:])
92		if err != nil {
93			return nil, fmt.Errorf("error parsing sockstat key/value pairs from %q: %v", s.Text(), err)
94		}
95
96		// The first field is the protocol. We must trim its colon suffix.
97		proto := strings.TrimSuffix(fields[0], ":")
98		switch proto {
99		case "sockets":
100			// Special case: IPv4 has a sockets "used" key/value pair that we
101			// embed at the top level of the structure.
102			used := kvs["used"]
103			stat.Used = &used
104		default:
105			// Parse all other lines as individual protocols.
106			nsp := parseSockstatProtocol(kvs)
107			nsp.Protocol = proto
108			stat.Protocols = append(stat.Protocols, nsp)
109		}
110	}
111
112	if err := s.Err(); err != nil {
113		return nil, err
114	}
115
116	return &stat, nil
117}
118
119// parseSockstatKVs parses a string slice into a map of key/value pairs.
120func parseSockstatKVs(kvs []string) (map[string]int, error) {
121	if len(kvs)%2 != 0 {
122		return nil, errors.New("odd number of fields in key/value pairs")
123	}
124
125	// Iterate two values at a time to gather key/value pairs.
126	out := make(map[string]int, len(kvs)/2)
127	for i := 0; i < len(kvs); i += 2 {
128		vp := util.NewValueParser(kvs[i+1])
129		out[kvs[i]] = vp.Int()
130
131		if err := vp.Err(); err != nil {
132			return nil, err
133		}
134	}
135
136	return out, nil
137}
138
139// parseSockstatProtocol parses a NetSockstatProtocol from the input kvs map.
140func parseSockstatProtocol(kvs map[string]int) NetSockstatProtocol {
141	var nsp NetSockstatProtocol
142	for k, v := range kvs {
143		// Capture the range variable to ensure we get unique pointers for
144		// each of the optional fields.
145		v := v
146		switch k {
147		case "inuse":
148			nsp.InUse = v
149		case "orphan":
150			nsp.Orphan = &v
151		case "tw":
152			nsp.TW = &v
153		case "alloc":
154			nsp.Alloc = &v
155		case "mem":
156			nsp.Mem = &v
157		case "memory":
158			nsp.Memory = &v
159		}
160	}
161
162	return nsp
163}
164