| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package apcupsd |
| 4 | |
| 5 | import ( |
| 6 | "bytes" |
| 7 | "encoding/binary" |
| 8 | "io" |
| 9 | "net" |
| 10 | "time" |
| 11 | ) |
| 12 | |
| 13 | type apcupsdConn interface { |
| 14 | connect() error |
| 15 | disconnect() error |
| 16 | status() ([]byte, error) |
| 17 | } |
| 18 | |
| 19 | func newUpsdConn(conf Config) apcupsdConn { |
| 20 | return &apcupsdClient{ |
| 21 | address: conf.Address, |
| 22 | timeout: conf.Timeout.Duration(), |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | type apcupsdClient struct { |
| 27 | address string |
| 28 | timeout time.Duration |
| 29 | conn net.Conn |
| 30 | } |
| 31 | |
| 32 | func (c *apcupsdClient) connect() error { |
| 33 | if c.conn != nil { |
| 34 | _ = c.disconnect() |
| 35 | } |
| 36 | |
| 37 | conn, err := net.DialTimeout("tcp", c.address, c.timeout) |
| 38 | if err != nil { |
| 39 | return err |
| 40 | } |
| 41 | |
| 42 | c.conn = conn |
| 43 | |
| 44 | return nil |
| 45 | } |
| 46 | |
| 47 | func (c *apcupsdClient) disconnect() error { |
| 48 | if c.conn != nil { |
| 49 | err := c.conn.Close() |
| 50 | c.conn = nil |
| 51 | return err |
| 52 | } |
| 53 | return nil |
| 54 | } |
| 55 | |
| 56 | func (c *apcupsdClient) status() ([]byte, error) { |
| 57 | if err := c.send("status"); err != nil { |
| 58 | return nil, err |
| 59 | } |
| 60 | return c.receive() |
| 61 | } |
| 62 | |
| 63 | func (c *apcupsdClient) send(cmd string) error { |
| 64 | // https://github.com/therealbstern/apcupsd/blob/224d19d5faa508d04267f6135fe53d50800550de/src/lib/apclibnis.c#L153 |
| 65 | |
| 66 | msgLength := make([]byte, 2) |
| 67 | |
| 68 | binary.BigEndian.PutUint16(msgLength, uint16(len(cmd))) |
| 69 | |
| 70 | if err := c.conn.SetWriteDeadline(c.deadline()); err != nil { |
| 71 | return err |
| 72 | } |
| 73 | |
| 74 | if _, err := c.conn.Write(append(msgLength, cmd...)); err != nil { |
| 75 | return err |
| 76 | } |
| 77 | |
| 78 | return nil |
| 79 | } |
| 80 | |
| 81 | func (c *apcupsdClient) receive() ([]byte, error) { |
| 82 | // https://github.com/therealbstern/apcupsd/blob/224d19d5faa508d04267f6135fe53d50800550de/src/apcnis.c#L54 |
| 83 | |
| 84 | var buf bytes.Buffer |
| 85 | msgLength := make([]byte, 2) |
| 86 | |
| 87 | for { |
| 88 | if err := c.conn.SetReadDeadline(c.deadline()); err != nil { |
| 89 | return nil, err |
| 90 | } |
| 91 | |
| 92 | if _, err := io.ReadFull(c.conn, msgLength); err != nil { |
| 93 | return nil, err |
| 94 | } |
| 95 | |
| 96 | length := binary.BigEndian.Uint16(msgLength) |
| 97 | if length == 0 { |
| 98 | break |
| 99 | } |
| 100 | |
| 101 | if err := c.conn.SetReadDeadline(c.deadline()); err != nil { |
| 102 | return nil, err |
| 103 | } |
| 104 | |
| 105 | if _, err := io.CopyN(&buf, c.conn, int64(length)); err != nil { |
| 106 | return nil, err |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | return buf.Bytes(), nil |
| 111 | } |
| 112 | |
| 113 | func (c *apcupsdClient) deadline() time.Time { |
| 114 | return time.Now().Add(c.timeout) |
| 115 | } |