source: code/trunk/vendor/github.com/prometheus/procfs/net_sockstat.go@ 822

// Copyright 2019 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"
        "bytes"
        "errors"
        "fmt"
        "io"
        "strings"

        "github.com/prometheus/procfs/internal/util"
)

// A NetSockstat contains the output of /proc/net/sockstat{,6} for IPv4 or IPv6,
// respectively.
type NetSockstat struct {
        // Used is non-nil for IPv4 sockstat results, but nil for IPv6.
        Used      *int
        Protocols []NetSockstatProtocol
}

// A NetSockstatProtocol contains statistics about a given socket protocol.
// Pointer fields indicate that the value may or may not be present on any
// given protocol.
type NetSockstatProtocol struct {
        Protocol string
        InUse    int
        Orphan   *int
        TW       *int
        Alloc    *int
        Mem      *int
        Memory   *int
}

// NetSockstat retrieves IPv4 socket statistics.
func (fs FS) NetSockstat() (*NetSockstat, error) {
        return readSockstat(fs.proc.Path("net", "sockstat"))
}

// NetSockstat6 retrieves IPv6 socket statistics.
//
// If IPv6 is disabled on this kernel, the returned error can be checked with
// os.IsNotExist.
func (fs FS) NetSockstat6() (*NetSockstat, error) {
        return readSockstat(fs.proc.Path("net", "sockstat6"))
}

// readSockstat opens and parses a NetSockstat from the input file.
func readSockstat(name string) (*NetSockstat, error) {
        // This file is small and can be read with one syscall.
        b, err := util.ReadFileNoStat(name)
        if err != nil {
                // Do not wrap this error so the caller can detect os.IsNotExist and
                // similar conditions.
                return nil, err
        }

        stat, err := parseSockstat(bytes.NewReader(b))
        if err != nil {
                return nil, fmt.Errorf("failed to read sockstats from %q: %w", name, err)
        }

        return stat, nil
}

// parseSockstat reads the contents of a sockstat file and parses a NetSockstat.
func parseSockstat(r io.Reader) (*NetSockstat, error) {
        var stat NetSockstat
        s := bufio.NewScanner(r)
        for s.Scan() {
                // Expect a minimum of a protocol and one key/value pair.
                fields := strings.Split(s.Text(), " ")
                if len(fields) < 3 {
                        return nil, fmt.Errorf("malformed sockstat line: %q", s.Text())
                }

                // The remaining fields are key/value pairs.
                kvs, err := parseSockstatKVs(fields[1:])
                if err != nil {
                        return nil, fmt.Errorf("error parsing sockstat key/value pairs from %q: %w", s.Text(), err)
                }

                // The first field is the protocol. We must trim its colon suffix.
                proto := strings.TrimSuffix(fields[0], ":")
                switch proto {
                case "sockets":
                        // Special case: IPv4 has a sockets "used" key/value pair that we
                        // embed at the top level of the structure.
                        used := kvs["used"]
                        stat.Used = &used
                default:
                        // Parse all other lines as individual protocols.
                        nsp := parseSockstatProtocol(kvs)
                        nsp.Protocol = proto
                        stat.Protocols = append(stat.Protocols, nsp)
                }
        }

        if err := s.Err(); err != nil {
                return nil, err
        }

        return &stat, nil
}

// parseSockstatKVs parses a string slice into a map of key/value pairs.
func parseSockstatKVs(kvs []string) (map[string]int, error) {
        if len(kvs)%2 != 0 {
                return nil, errors.New("odd number of fields in key/value pairs")
        }

        // Iterate two values at a time to gather key/value pairs.
        out := make(map[string]int, len(kvs)/2)
        for i := 0; i < len(kvs); i += 2 {
                vp := util.NewValueParser(kvs[i+1])
                out[kvs[i]] = vp.Int()

                if err := vp.Err(); err != nil {
                        return nil, err
                }
        }

        return out, nil
}

// parseSockstatProtocol parses a NetSockstatProtocol from the input kvs map.
func parseSockstatProtocol(kvs map[string]int) NetSockstatProtocol {
        var nsp NetSockstatProtocol
        for k, v := range kvs {
                // Capture the range variable to ensure we get unique pointers for
                // each of the optional fields.
                v := v
                switch k {
                case "inuse":
                        nsp.InUse = v
                case "orphan":
                        nsp.Orphan = &v
                case "tw":
                        nsp.TW = &v
                case "alloc":
                        nsp.Alloc = &v
                case "mem":
                        nsp.Mem = &v
                case "memory":
                        nsp.Memory = &v
                }
        }

        return nsp
}