/
client.go
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/
client.go
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/*
Copyright 2022 Loophole Labs
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 frisbee
import (
"context"
"github.com/loopholelabs/frisbee-go/pkg/packet"
"github.com/rs/zerolog"
"go.uber.org/atomic"
"net"
"sync"
)
// Client connects to a frisbee Server and can send and receive frisbee packets
type Client struct {
conn *Async
handlerTable HandlerTable
ctx context.Context
options *Options
closed *atomic.Bool
wg sync.WaitGroup
heartbeatChannel chan struct{}
// PacketContext is used to define packet-specific contexts based on the incoming packet
// and is run whenever a new packet arrives
PacketContext func(context.Context, *packet.Packet) context.Context
// UpdateContext is used to update a handler-specific context whenever the returned
// Action from a handler is UPDATE
UpdateContext func(context.Context, *Async) context.Context
}
// NewClient returns an uninitialized frisbee Client with the registered ClientRouter.
// The ConnectAsync method must then be called to dial the server and initialize the connection.
func NewClient(handlerTable HandlerTable, ctx context.Context, opts ...Option) (*Client, error) {
for i := uint16(0); i < RESERVED9; i++ {
if _, ok := handlerTable[i]; ok {
return nil, InvalidHandlerTable
}
}
options := loadOptions(opts...)
var heartbeatChannel chan struct{}
return &Client{
handlerTable: handlerTable,
ctx: ctx,
options: options,
closed: atomic.NewBool(false),
heartbeatChannel: heartbeatChannel,
}, nil
}
// Connect actually connects to the given frisbee server, and starts the reactor goroutines
// to receive and handle incoming packets. If this function is called, FromConn should not be called.
func (c *Client) Connect(addr string, streamHandler ...NewStreamHandler) error {
c.Logger().Debug().Msgf("Connecting to %s", addr)
var frisbeeConn *Async
var err error
frisbeeConn, err = ConnectAsync(addr, c.options.KeepAlive, c.Logger(), c.options.TLSConfig, streamHandler...)
if err != nil {
return err
}
c.conn = frisbeeConn
c.Logger().Info().Msgf("Connected to %s", addr)
c.wg.Add(1)
go c.handleConn()
c.Logger().Debug().Msgf("Connection handler started for %s", addr)
return nil
}
// FromConn takes a pre-existing connection to a Frisbee server and starts the reactor goroutines
// to receive and handle incoming packets. If this function is called, Connect should not be called.
func (c *Client) FromConn(conn net.Conn, streamHandler ...NewStreamHandler) error {
c.conn = NewAsync(conn, c.Logger(), streamHandler...)
c.wg.Add(1)
go c.handleConn()
c.Logger().Debug().Msgf("Connection handler started for %s", c.conn.RemoteAddr())
return nil
}
// Closed checks whether this client has been closed
func (c *Client) Closed() bool {
return c.closed.Load()
}
// Error checks whether this client has an error
func (c *Client) Error() error {
return c.conn.Error()
}
// Close closes the frisbee client and kills all the goroutines
func (c *Client) Close() error {
if c.closed.CompareAndSwap(false, true) {
err := c.conn.Close()
if err != nil {
return err
}
c.wg.Wait()
return nil
}
return c.conn.Close()
}
// WritePacket sends a frisbee packet.Packet from the client to the server
func (c *Client) WritePacket(p *packet.Packet) error {
return c.conn.WritePacket(p)
}
// Flush flushes any queued frisbee Packets from the client to the server
func (c *Client) Flush() error {
return c.conn.Flush()
}
// CloseChannel returns a channel that can be listened to see if this client has been closed
func (c *Client) CloseChannel() <-chan struct{} {
return c.conn.CloseChannel()
}
// Raw converts the frisbee client into a normal net.Conn object, and returns it.
// This is especially useful in proxying and streaming scenarios.
func (c *Client) Raw() (net.Conn, error) {
if c.conn == nil {
return nil, ConnectionNotInitialized
}
if c.closed.CompareAndSwap(false, true) {
conn := c.conn.Raw()
c.wg.Wait()
return conn, nil
}
return c.conn.Raw(), nil
}
// Stream returns a new Stream object that can be used to send and receive frisbee packets
func (c *Client) Stream(id uint16) *Stream {
return c.conn.NewStream(id)
}
// SetNewStreamHandler sets the callback handler for new streams.
//
// It's important to note that this handler is called for new streams and if it is
// not set then stream packets will be dropped.
//
// It's also important to note that the handler itself is called in its own goroutine to
// avoid blocking the read lop. This means that the handler must be thread-safe.
func (c *Client) SetNewStreamHandler(handler NewStreamHandler) {
c.conn.SetNewStreamHandler(handler)
}
// Logger returns the client's logger (useful for ClientRouter functions)
func (c *Client) Logger() *zerolog.Logger {
return c.options.Logger
}
func (c *Client) handleConn() {
var p *packet.Packet
var outgoing *packet.Packet
var action Action
var err error
var handlerFunc Handler
for {
if c.closed.Load() {
c.wg.Done()
return
}
p, err = c.conn.ReadPacket()
if err != nil {
c.Logger().Debug().Err(err).Msg("error while getting packet frisbee connection")
c.wg.Done()
_ = c.Close()
return
}
handlerFunc = c.handlerTable[p.Metadata.Operation]
if handlerFunc != nil {
packetCtx := c.ctx
if c.PacketContext != nil {
packetCtx = c.PacketContext(packetCtx, p)
}
outgoing, action = handlerFunc(packetCtx, p)
if outgoing != nil && outgoing.Metadata.ContentLength == uint32(outgoing.Content.Len()) {
err = c.conn.WritePacket(outgoing)
if outgoing != p {
packet.Put(outgoing)
}
packet.Put(p)
if err != nil {
c.Logger().Error().Err(err).Msg("error while writing to frisbee conn")
c.wg.Done()
_ = c.Close()
return
}
} else {
packet.Put(p)
}
switch action {
case NONE:
case CLOSE:
c.Logger().Debug().Msgf("Closing connection %s because of CLOSE action", c.conn.RemoteAddr())
c.wg.Done()
_ = c.Close()
return
}
} else {
packet.Put(p)
}
}
}