rpcfetch/io.go

package rpcfetch

import (
	"encoding/binary"
	"encoding/json"
	"errors"
	"net"
	"os"
	"strconv"
	"syscall"
)

type Client struct {
	id string

	config *Config
	user   *User

	dialed bool
	active bool
	conn   net.Conn
}

// Raw wraps around the Raw method to provide generic json parsing
func Raw[T any](d *Client, opcode uint32, payload any) (uint32, T, error) {
	var p T

	opcodeResp, payloadResp, err := d.Raw(opcode, payload)
	if err != nil {
		return opcodeResp, p, err
	}

	return opcodeResp, p, json.Unmarshal(payloadResp, &p)
}

// Raw writes a raw payload to Discord and returns the response opcode and payload
func (d *Client) Raw(opcode uint32, payload any) (uint32, []byte, error) {
	opcodeResp, payloadResp, err := d.raw(opcode, payload)
	if errors.Is(err, syscall.EPIPE) {
		// clean up as much as possible
		_ = d.Close()
		// advise retry
		err = ErrAgain
	}
	return opcodeResp, payloadResp, err
}

func (d *Client) raw(opcode uint32, payload any) (uint32, []byte, error) {
	if err := binary.Write(d.conn, binary.LittleEndian, opcode); err != nil {
		return 0, nil, err
	}

	if p, err := json.Marshal(payload); err != nil {
		return 0, nil, err
	} else {
		if err = binary.Write(d.conn, binary.LittleEndian, uint32(len(p))); err != nil {
			return 0, nil, err
		}

		if _, err = d.conn.Write(p); err != nil {
			return 0, nil, err
		}
	}

	var (
		opcodeResp uint32
		lengthResp uint32
	)

	if err := binary.Read(d.conn, binary.LittleEndian, &opcodeResp); err != nil {
		return 0, nil, err
	}

	if err := binary.Read(d.conn, binary.LittleEndian, &lengthResp); err != nil {
		return 0, nil, err
	}

	payloadResp := make([]byte, lengthResp)
	_, err := d.conn.Read(payloadResp)
	return opcodeResp, payloadResp, err
}

// Close the client, this is required before exit
func (d *Client) Close() error {
	if !d.dialed {
		// silently succeed because client activation is implicit
		return nil
	}

	d.active = false
	d.dialed = false
	return d.conn.Close()
}

// New sets up and returns the reference to a new Client
func New(id string) *Client {
	d := &Client{
		id: id,
	}

	return d
}

func sockPath() string {
	snap := "/run/user/" + strconv.Itoa(os.Getuid()) + "/snap.discord"

	if _, err := os.Stat(snap); err == nil {
		return snap
	}

	for _, env := range []string{"XDG_RUNTIME_DIR", "TMPDIR", "TMP", "TEMP"} {
		if val, ok := os.LookupEnv(env); ok {
			return val
		}
	}

	// fallback
	return "/tmp"
}