From 604d4fc6526a1e7c7aa6aa33b73270d3fc47cb03 Mon Sep 17 00:00:00 2001
From: Siyuan Ren <netheril96@gmail.com>
Date: Fri, 30 Dec 2022 11:55:42 +0800
Subject: [PATCH 1/2] Add `lazy_start` option.

When on, the client will not attempt to connect to the server at
startup, only when a connection is initiated.
---
 app/cmd/client.go |  8 +++++++-
 app/cmd/config.go |  1 +
 core/cs/client.go | 33 +++++++++++++++++++--------------
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/app/cmd/client.go b/app/cmd/client.go
index bf11fef..f48ac09 100644
--- a/app/cmd/client.go
+++ b/app/cmd/client.go
@@ -136,6 +136,7 @@ func client(config *clientConfig) {
 	for {
 		try += 1
 		c, err := cs.NewClient(config.Server, auth, tlsConfig, quicConfig, pktConnFunc, up, down, config.FastOpen,
+			config.LazyStart,
 			func(err error) {
 				if config.QuitOnDisconnect {
 					logrus.WithFields(logrus.Fields{
@@ -170,7 +171,12 @@ func client(config *clientConfig) {
 		}
 	}
 	defer client.Close()
-	logrus.WithField("addr", config.Server).Info("Connected")
+	if config.LazyStart {
+		logrus.WithField("addr", config.Server).Info("Option lazy_start specified. Server connection deferred.")
+
+	} else {
+		logrus.WithField("addr", config.Server).Info("Connected")
+	}
 
 	// Local
 	errChan := make(chan error)
diff --git a/app/cmd/config.go b/app/cmd/config.go
index 65f7e4e..67b30f0 100644
--- a/app/cmd/config.go
+++ b/app/cmd/config.go
@@ -227,6 +227,7 @@ type clientConfig struct {
 	ReceiveWindow       uint64 `json:"recv_window"`
 	DisableMTUDiscovery bool   `json:"disable_mtu_discovery"`
 	FastOpen            bool   `json:"fast_open"`
+	LazyStart           bool   `json:"lazy_start"`
 	Resolver            string `json:"resolver"`
 	ResolvePreference   string `json:"resolve_preference"`
 }
diff --git a/core/cs/client.go b/core/cs/client.go
index d139d3f..93d3249 100644
--- a/core/cs/client.go
+++ b/core/cs/client.go
@@ -49,7 +49,7 @@ type Client struct {
 }
 
 func NewClient(serverAddr string, auth []byte, tlsConfig *tls.Config, quicConfig *quic.Config,
-	pktConnFunc pktconns.ClientPacketConnFunc, sendBPS uint64, recvBPS uint64, fastOpen bool,
+	pktConnFunc pktconns.ClientPacketConnFunc, sendBPS uint64, recvBPS uint64, fastOpen bool, lazyStart bool,
 	quicReconnectFunc func(err error),
 ) (*Client, error) {
 	quicConfig.DisablePathMTUDiscovery = quicConfig.DisablePathMTUDiscovery || pmtud.DisablePathMTUDiscovery
@@ -64,6 +64,9 @@ func NewClient(serverAddr string, auth []byte, tlsConfig *tls.Config, quicConfig
 		pktConnFunc:       pktConnFunc,
 		quicReconnectFunc: quicReconnectFunc,
 	}
+	if lazyStart {
+		return c, nil
+	}
 	if err := c.connect(); err != nil {
 		return nil, err
 	}
@@ -182,18 +185,20 @@ func (c *Client) openStreamWithReconnect() (quic.Connection, quic.Stream, error)
 	if c.closed {
 		return nil, nil, ErrClosed
 	}
-	stream, err := c.quicConn.OpenStream()
-	if err == nil {
-		// All good
-		return c.quicConn, &qStream{stream}, nil
-	}
-	// Something is wrong
-	if nErr, ok := err.(net.Error); ok && nErr.Temporary() {
-		// Temporary error, just return
-		return nil, nil, err
-	}
-	if c.quicReconnectFunc != nil {
-		c.quicReconnectFunc(err)
+	if c.quicConn != nil {
+		stream, err := c.quicConn.OpenStream()
+		if err == nil {
+			// All good
+			return c.quicConn, &qStream{stream}, nil
+		}
+		// Something is wrong
+		if nErr, ok := err.(net.Error); ok && nErr.Temporary() {
+			// Temporary error, just return
+			return nil, nil, err
+		}
+		if c.quicReconnectFunc != nil {
+			c.quicReconnectFunc(err)
+		}
 	}
 	// Permanent error, need to reconnect
 	if err := c.connect(); err != nil {
@@ -201,7 +206,7 @@ func (c *Client) openStreamWithReconnect() (quic.Connection, quic.Stream, error)
 		return nil, nil, err
 	}
 	// We are not going to try again even if it still fails the second time
-	stream, err = c.quicConn.OpenStream()
+	stream, err := c.quicConn.OpenStream()
 	return c.quicConn, &qStream{stream}, err
 }
 

From 20898f2990309574bd5d90f5a76cd3043c288467 Mon Sep 17 00:00:00 2001
From: tobyxdd <tobyxdd@gmail.com>
Date: Sat, 18 Feb 2023 20:01:01 -0800
Subject: [PATCH 2/2] chore: change info string

---
 app/cmd/client.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/app/cmd/client.go b/app/cmd/client.go
index f48ac09..3f51e86 100644
--- a/app/cmd/client.go
+++ b/app/cmd/client.go
@@ -172,8 +172,7 @@ func client(config *clientConfig) {
 	}
 	defer client.Close()
 	if config.LazyStart {
-		logrus.WithField("addr", config.Server).Info("Option lazy_start specified. Server connection deferred.")
-
+		logrus.WithField("addr", config.Server).Info("Lazy start enabled, waiting for first connection")
 	} else {
 		logrus.WithField("addr", config.Server).Info("Connected")
 	}