Yggdrasil demo updates

Squashed commit of the following:

commit 6c2c48f862c1b6f8e741c57804282eceffe02487
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Fri Jul 10 16:28:09 2020 +0100

    Add README.md

commit 5eeefdadf8e3881dd7a32559a92be49bd7ddaf47
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Fri Jul 10 10:18:50 2020 +0100

    Fix wedge in federation sender

commit e2ebffbfba25cf82378393940a613ec32bfb909f
Merge: 0883ef88 abf26c12
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Fri Jul 10 09:51:23 2020 +0100

    Merge branch 'master' into neilalexander/yggdrasil

commit 0883ef8870e340f2ae9a0c37ed939dc2ab9911f6
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Fri Jul 10 09:51:06 2020 +0100

    Adjust timeouts

commit ba2d53199910f13b60cc892debe96a962e8c9acb
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Thu Jul 9 16:34:40 2020 +0100

    Try to wake up from peers/sessions properly

commit 73f42eb494741ba5b0e0cef43654708e3c8eb399
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Thu Jul 9 15:43:38 2020 +0100

    Use TransactionWriter to reduce database lock issues on SQLite

commit 08bfe63241a18c58c539c91b9f52edccda63a611
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Thu Jul 9 12:38:02 2020 +0100

    Un-wedge federation

    Squashed commit of the following:

    commit aee933f8785e7a7998105f6090f514d18051a1bd
    Author: Neil Alexander <neilalexander@users.noreply.github.com>
    Date:   Thu Jul 9 12:22:41 2020 +0100

        Un-goroutine the goroutines

    commit 478374e5d18a3056cac6682ef9095d41352d1295
    Author: Neil Alexander <neilalexander@users.noreply.github.com>
    Date:   Thu Jul 9 12:09:31 2020 +0100

        Reduce federation sender wedges

commit 40cc62c54d9e3a863868214c48b7c18e522a4772
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Thu Jul 9 10:02:52 2020 +0100

    Handle switching in/out background more reliably

5 files changed, 50 insertions, 22 deletions

diff --git a/cmd/dendrite-demo-yggdrasil/README.md b/cmd/dendrite-demo-yggdrasil/README.md
new file mode 100644
index 00000000..148b9a58
--- /dev/null
+++ b/cmd/dendrite-demo-yggdrasil/README.md
@@ -0,0 +1,22 @@
+# Yggdrasil Demo
+
+This is the Dendrite Yggdrasil demo! It's easy to get started - all you need is Go 1.13 or later.
+
+To run the homeserver, start at the root of the Dendrite repository and run:
+
+```
+go run ./cmd/dendrite-demo-yggdrasil
+```
+
+The following command line arguments are accepted:
+
+* `-peer tcp://a.b.c.d:e` to specify a static Yggdrasil peer to connect to - you will need to supply this if you do not have another Yggdrasil node on your network
+* `-port 12345` to specify a port to listen on for client connections
+
+If you need to find an internet peer, take a look at [this list](https://publicpeers.neilalexander.dev/). 
+
+Then point your favourite Matrix client to  the homeserver URL`http://localhost:8008` (or whichever `-port` you specified), create an account and log in.
+
+If your peering connection is operational then you should see a `Connected TCP:` line in the log output. If not then try a different peer.
+
+Once logged in, you should be able to open the room directory or join a room by its ID.
\ No newline at end of file
diff --git a/cmd/dendrite-demo-yggdrasil/main.go b/cmd/dendrite-demo-yggdrasil/main.go
index 65747756..122d0266 100644
--- a/cmd/dendrite-demo-yggdrasil/main.go
+++ b/cmd/dendrite-demo-yggdrasil/main.go
@@ -17,6 +17,7 @@ package main
 import (
 	"context"
 	"crypto/tls"
+	"encoding/hex"
 	"flag"
 	"fmt"
 	"net"
@@ -154,27 +155,28 @@ func main() {
 		base.UseHTTPAPIs,
 	)
 
-	ygg.NotifySessionNew(func(boxPubKey crypto.BoxPubKey) {
+	ygg.NewSession = func(serverName gomatrixserverlib.ServerName) {
+		logrus.Infof("Found new session %q", serverName)
 		req := &api.PerformServersAliveRequest{
-			Servers: []gomatrixserverlib.ServerName{
-				gomatrixserverlib.ServerName(boxPubKey.String()),
-			},
+			Servers: []gomatrixserverlib.ServerName{serverName},
 		}
 		res := &api.PerformServersAliveResponse{}
 		if err := fsAPI.PerformServersAlive(context.TODO(), req, res); err != nil {
 			logrus.WithError(err).Warn("Failed to notify server alive due to new session")
 		}
-	})
+	}
 
-	ygg.NotifyLinkNew(func(boxPubKey crypto.BoxPubKey, linkType, remote string) {
+	ygg.NotifyLinkNew(func(_ crypto.BoxPubKey, sigPubKey crypto.SigPubKey, linkType, remote string) {
+		serverName := hex.EncodeToString(sigPubKey[:])
+		logrus.Infof("Found new peer %q", serverName)
 		req := &api.PerformServersAliveRequest{
 			Servers: []gomatrixserverlib.ServerName{
-				gomatrixserverlib.ServerName(boxPubKey.String()),
+				gomatrixserverlib.ServerName(serverName),
 			},
 		}
 		res := &api.PerformServersAliveResponse{}
 		if err := fsAPI.PerformServersAlive(context.TODO(), req, res); err != nil {
-			logrus.WithError(err).Warn("Failed to notify server alive due to new link")
+			logrus.WithError(err).Warn("Failed to notify server alive due to new session")
 		}
 	})
 
diff --git a/cmd/dendrite-demo-yggdrasil/yggconn/client.go b/cmd/dendrite-demo-yggdrasil/yggconn/client.go
index 399993e3..b74468db 100644
--- a/cmd/dendrite-demo-yggdrasil/yggconn/client.go
+++ b/cmd/dendrite-demo-yggdrasil/yggconn/client.go
@@ -46,7 +46,8 @@ func (n *Node) CreateClient(
 	tr.RegisterProtocol(
 		"matrix", &yggroundtripper{
 			inner: &http.Transport{
-				ResponseHeaderTimeout: 15 * time.Second,
+				TLSHandshakeTimeout:   20 * time.Second,
+				ResponseHeaderTimeout: 10 * time.Second,
 				IdleConnTimeout:       60 * time.Second,
 				DialContext:           n.yggdialerctx,
 			},
@@ -62,7 +63,8 @@ func (n *Node) CreateFederationClient(
 	tr.RegisterProtocol(
 		"matrix", &yggroundtripper{
 			inner: &http.Transport{
-				ResponseHeaderTimeout: 15 * time.Second,
+				TLSHandshakeTimeout:   20 * time.Second,
+				ResponseHeaderTimeout: 10 * time.Second,
 				IdleConnTimeout:       60 * time.Second,
 				DialContext:           n.yggdialerctx,
 			},
diff --git a/cmd/dendrite-demo-yggdrasil/yggconn/node.go b/cmd/dendrite-demo-yggdrasil/yggconn/node.go
index 89fb69b5..2bc300c8 100644
--- a/cmd/dendrite-demo-yggdrasil/yggconn/node.go
+++ b/cmd/dendrite-demo-yggdrasil/yggconn/node.go
@@ -55,6 +55,7 @@ type Node struct {
 	quicConfig *quic.Config
 	sessions   sync.Map // string -> quic.Session
 	incoming   chan QUICStream
+	NewSession func(remote gomatrixserverlib.ServerName)
 }
 
 func (n *Node) BuildName() string {
@@ -137,7 +138,7 @@ func Setup(instanceName, storageDirectory string) (*Node, error) {
 		MaxIncomingStreams:    0,
 		MaxIncomingUniStreams: 0,
 		KeepAlive:             true,
-		MaxIdleTimeout:        time.Second * 60,
+		MaxIdleTimeout:        time.Minute * 15,
 		HandshakeTimeout:      time.Second * 15,
 	}
 
@@ -189,7 +190,9 @@ func (n *Node) PeerCount() int {
 }
 
 func (n *Node) KnownNodes() []gomatrixserverlib.ServerName {
-	nodemap := map[string]struct{}{}
+	nodemap := map[string]struct{}{
+		"b5ae50589e50991dd9dd7d59c5c5f7a4521e8da5b603b7f57076272abc58b374": struct{}{},
+	}
 	for _, peer := range n.core.GetSwitchPeers() {
 		nodemap[hex.EncodeToString(peer.SigningKey[:])] = struct{}{}
 	}
@@ -264,18 +267,10 @@ func (n *Node) SetStaticPeer(uri string) error {
 	return nil
 }
 
-func (n *Node) NotifyLinkNew(f func(boxPubKey crypto.BoxPubKey, linkType, remote string)) {
+func (n *Node) NotifyLinkNew(f func(boxPubKey crypto.BoxPubKey, sigPubKey crypto.SigPubKey, linkType, remote string)) {
 	n.core.NotifyLinkNew(f)
 }
 
-func (n *Node) NotifyLinkGone(f func(boxPubKey crypto.BoxPubKey, linkType, remote string)) {
+func (n *Node) NotifyLinkGone(f func(boxPubKey crypto.BoxPubKey, sigPubKey crypto.SigPubKey, linkType, remote string)) {
 	n.core.NotifyLinkGone(f)
 }
-
-func (n *Node) NotifySessionNew(f func(boxPubKey crypto.BoxPubKey)) {
-	n.core.NotifySessionNew(f)
-}
-
-func (n *Node) NotifySessionGone(f func(boxPubKey crypto.BoxPubKey)) {
-	n.core.NotifySessionGone(f)
-}
diff --git a/cmd/dendrite-demo-yggdrasil/yggconn/session.go b/cmd/dendrite-demo-yggdrasil/yggconn/session.go
index 01cec813..ff77e64f 100644
--- a/cmd/dendrite-demo-yggdrasil/yggconn/session.go
+++ b/cmd/dendrite-demo-yggdrasil/yggconn/session.go
@@ -29,6 +29,7 @@ import (
 	"time"
 
 	"github.com/lucas-clemente/quic-go"
+	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 )
 
@@ -56,6 +57,12 @@ func (n *Node) listenFromYgg() {
 func (n *Node) listenFromQUIC(session quic.Session) {
 	n.sessions.Store(session.RemoteAddr().String(), session)
 	defer n.sessions.Delete(session.RemoteAddr())
+	if n.NewSession != nil {
+		if len(session.ConnectionState().PeerCertificates) == 1 {
+			subjectName := session.ConnectionState().PeerCertificates[0].Subject.CommonName
+			go n.NewSession(gomatrixserverlib.ServerName(subjectName))
+		}
+	}
 	for {
 		st, err := session.AcceptStream(context.TODO())
 		if err != nil {