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package yamux
import (
"fmt"
"io"
"log"
"os"
"time"
)
// Config is used to tune the Yamux session
type Config struct {
// AcceptBacklog is used to limit how many streams may be
// waiting an accept.
AcceptBacklog int
// EnableKeepalive is used to do a period keep alive
// messages using a ping.
EnableKeepAlive bool
// KeepAliveInterval is how often to perform the keep alive
KeepAliveInterval time.Duration
// ConnectionWriteTimeout is meant to be a "safety valve" timeout after
// we which will suspect a problem with the underlying connection and
// close it. This is only applied to writes, where's there's generally
// an expectation that things will move along quickly.
ConnectionWriteTimeout time.Duration
// MaxStreamWindowSize is used to control the maximum
// window size that we allow for a stream.
MaxStreamWindowSize uint32
// StreamOpenTimeout is the maximum amount of time that a stream will
// be allowed to remain in pending state while waiting for an ack from the peer.
// Once the timeout is reached the session will be gracefully closed.
// A zero value disables the StreamOpenTimeout allowing unbounded
// blocking on OpenStream calls.
StreamOpenTimeout time.Duration
// StreamCloseTimeout is the maximum time that a stream will allowed to
// be in a half-closed state when `Close` is called before forcibly
// closing the connection. Forcibly closed connections will empty the
// receive buffer, drop any future packets received for that stream,
// and send a RST to the remote side.
StreamCloseTimeout time.Duration
// LogOutput is used to control the log destination. Either Logger or
// LogOutput can be set, not both.
LogOutput io.Writer
// Logger is used to pass in the logger to be used. Either Logger or
// LogOutput can be set, not both.
Logger *log.Logger
}
// DefaultConfig is used to return a default configuration
func DefaultConfig() *Config {
return &Config{
AcceptBacklog: 256,
EnableKeepAlive: true,
KeepAliveInterval: 30 * time.Second,
ConnectionWriteTimeout: 10 * time.Second,
MaxStreamWindowSize: initialStreamWindow,
StreamCloseTimeout: 5 * time.Minute,
StreamOpenTimeout: 75 * time.Second,
LogOutput: os.Stderr,
}
}
// VerifyConfig is used to verify the sanity of configuration
func VerifyConfig(config *Config) error {
if config.AcceptBacklog <= 0 {
return fmt.Errorf("backlog must be positive")
}
if config.KeepAliveInterval == 0 {
return fmt.Errorf("keep-alive interval must be positive")
}
if config.MaxStreamWindowSize < initialStreamWindow {
return fmt.Errorf("MaxStreamWindowSize must be larger than %d", initialStreamWindow)
}
if config.LogOutput != nil && config.Logger != nil {
return fmt.Errorf("both Logger and LogOutput may not be set, select one")
} else if config.LogOutput == nil && config.Logger == nil {
return fmt.Errorf("one of Logger or LogOutput must be set, select one")
}
return nil
}
// Server is used to initialize a new server-side connection.
// There must be at most one server-side connection. If a nil config is
// provided, the DefaultConfiguration will be used.
func Server(conn io.ReadWriteCloser, config *Config) (*Session, error) {
if config == nil {
config = DefaultConfig()
}
if err := VerifyConfig(config); err != nil {
return nil, err
}
return newSession(config, conn, false), nil
}
// Client is used to initialize a new client-side connection.
// There must be at most one client-side connection.
func Client(conn io.ReadWriteCloser, config *Config) (*Session, error) {
if config == nil {
config = DefaultConfig()
}
if err := VerifyConfig(config); err != nil {
return nil, err
}
return newSession(config, conn, true), nil
}
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