| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package socket |
| 4 | |
| 5 | import ( |
| 6 | "bufio" |
| 7 | "context" |
| 8 | "crypto/tls" |
| 9 | "errors" |
| 10 | "fmt" |
| 11 | "net" |
| 12 | "time" |
| 13 | ) |
| 14 | |
| 15 | // Processor is a callback function passed to the Socket.Command method. |
| 16 | // It processes each response line received from the server. |
| 17 | type Processor func([]byte) (bool, error) |
| 18 | |
| 19 | // Client defines an interface for socket clients, abstracting the underlying implementation. |
| 20 | // Implementations should provide connections for various socket types such as TCP, UDP, or Unix domain sockets. |
| 21 | type Client interface { |
| 22 | Connect() error |
| 23 | Disconnect() error |
| 24 | Command(command string, process Processor) error |
| 25 | } |
| 26 | |
| 27 | // ConnectAndRead establishes a connection using the given configuration, |
| 28 | // executes the provided processor function on the incoming response lines, |
| 29 | // and ensures the connection is properly closed after use. |
| 30 | func ConnectAndRead(cfg Config, process Processor) error { |
| 31 | sock := New(cfg) |
| 32 | |
| 33 | if err := sock.Connect(); err != nil { |
| 34 | return err |
| 35 | } |
| 36 | |
| 37 | defer func() { _ = sock.Disconnect() }() |
| 38 | |
| 39 | return sock.read(process) |
| 40 | } |
| 41 | |
| 42 | // New creates and returns a new Socket instance configured with the provided settings. |
| 43 | // The socket supports multiple types (TCP, UDP, UNIX), addresses (IPv4, IPv6, domain names), |
| 44 | // and optional TLS encryption. Connections are reused where possible. |
| 45 | func New(cfg Config) *Socket { |
| 46 | return &Socket{Config: cfg} |
| 47 | } |
| 48 | |
| 49 | // Socket is a concrete implementation of the Client interface, managing a network connection |
| 50 | // based on the specified configuration (address, type, timeout, and optional TLS settings). |
| 51 | type Socket struct { |
| 52 | Config |
| 53 | conn net.Conn |
| 54 | } |
| 55 | |
| 56 | // Config encapsulates the settings required to establish a network connection. |
| 57 | type Config struct { |
| 58 | Address string |
| 59 | Timeout time.Duration |
| 60 | TLSConf *tls.Config |
| 61 | MaxReadLines int64 |
| 62 | } |
| 63 | |
| 64 | // Connect establishes a connection to the specified address using the configuration details. |
| 65 | func (s *Socket) Connect() error { |
| 66 | conn, err := s.dial() |
| 67 | if err != nil { |
| 68 | return fmt.Errorf("socket.Connect: %w", err) |
| 69 | } |
| 70 | |
| 71 | s.conn = conn |
| 72 | |
| 73 | return nil |
| 74 | } |
| 75 | |
| 76 | // Disconnect terminates the active connection if one exists. |
| 77 | func (s *Socket) Disconnect() error { |
| 78 | if s.conn == nil { |
| 79 | return nil |
| 80 | } |
| 81 | err := s.conn.Close() |
| 82 | s.conn = nil |
| 83 | return err |
| 84 | } |
| 85 | |
| 86 | // Command sends a command string to the connected server and processes its response line by line |
| 87 | // using the provided Processor function. This method respects the timeout configuration |
| 88 | // for write and read operations. If a timeout or processing error occurs, it stops and returns the error. |
| 89 | func (s *Socket) Command(command string, process Processor) error { |
| 90 | if s.conn == nil { |
| 91 | return errors.New("cannot send command on nil connection") |
| 92 | } |
| 93 | |
| 94 | if err := s.write(command); err != nil { |
| 95 | return err |
| 96 | } |
| 97 | |
| 98 | return s.read(process) |
| 99 | } |
| 100 | |
| 101 | func (s *Socket) write(command string) error { |
| 102 | if s.conn == nil { |
| 103 | return errors.New("write: nil connection") |
| 104 | } |
| 105 | |
| 106 | if err := s.conn.SetWriteDeadline(s.deadline()); err != nil { |
| 107 | return err |
| 108 | } |
| 109 | |
| 110 | _, err := s.conn.Write([]byte(command)) |
| 111 | |
| 112 | return err |
| 113 | } |
| 114 | |
| 115 | func (s *Socket) read(process Processor) error { |
| 116 | if process == nil { |
| 117 | return errors.New("read: process func is nil") |
| 118 | } |
| 119 | if s.conn == nil { |
| 120 | return errors.New("read: nil connection") |
| 121 | } |
| 122 | |
| 123 | if err := s.conn.SetReadDeadline(s.deadline()); err != nil { |
| 124 | return err |
| 125 | } |
| 126 | |
| 127 | sc := bufio.NewScanner(s.conn) |
| 128 | |
| 129 | var n int64 |
| 130 | limit := s.MaxReadLines |
| 131 | |
| 132 | for sc.Scan() { |
| 133 | more, err := process(sc.Bytes()) |
| 134 | if err != nil { |
| 135 | return err |
| 136 | } |
| 137 | if n++; limit > 0 && n > limit { |
| 138 | return fmt.Errorf("read line limit exceeded (%d", limit) |
| 139 | } |
| 140 | if !more { |
| 141 | break |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | return sc.Err() |
| 146 | } |
| 147 | |
| 148 | func (s *Socket) dial() (net.Conn, error) { |
| 149 | network, address := parseAddress(s.Address) |
| 150 | |
| 151 | var d net.Dialer |
| 152 | d.Timeout = s.timeout() |
| 153 | |
| 154 | if s.TLSConf != nil { |
| 155 | return tls.DialWithDialer(&d, network, address, s.TLSConf) |
| 156 | } |
| 157 | return d.DialContext(context.Background(), network, address) |
| 158 | } |
| 159 | |
| 160 | func (s *Socket) deadline() time.Time { |
| 161 | return time.Now().Add(s.timeout()) |
| 162 | } |
| 163 | |
| 164 | func (s *Socket) timeout() time.Duration { |
| 165 | if s.Timeout == 0 { |
| 166 | return time.Second |
| 167 | } |
| 168 | return s.Timeout |
| 169 | } |