TUN-2714: New edge discovery. Connections try to reconnect to the same edge IP.

edgediscovery/edgediscovery.go

@@ -0,0 +1,143 @@
+package edgediscovery
+
+import (
+	"fmt"
+	"net"
+	"sync"
+
+	"github.com/cloudflare/cloudflared/edgediscovery/allregions"
+
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	subsystem = "edgediscovery"
+)
+
+var errNoAddressesLeft = fmt.Errorf("There are no free edge addresses left")
+
+// Edge finds addresses on the Cloudflare edge and hands them out to connections.
+type Edge struct {
+	regions *allregions.Regions
+	sync.Mutex
+	logger *logrus.Entry
+}
+
+// ------------------------------------
+// Constructors
+// ------------------------------------
+
+// ResolveEdge runs the initial discovery of the Cloudflare edge, finding Addrs that can be allocated
+// to connections.
+func ResolveEdge(l *logrus.Logger) (*Edge, error) {
+	logger := l.WithField("subsystem", subsystem)
+	regions, err := allregions.ResolveEdge(logger)
+	if err != nil {
+		return new(Edge), err
+	}
+	return &Edge{
+		logger:  logger,
+		regions: regions,
+	}, nil
+}
+
+// StaticEdge creates a list of edge addresses from the list of hostnames. Mainly used for testing connectivity.
+func StaticEdge(l *logrus.Logger, hostnames []string) (*Edge, error) {
+	logger := l.WithField("subsystem", subsystem)
+	regions, err := allregions.StaticEdge(hostnames)
+	if err != nil {
+		return new(Edge), err
+	}
+	return &Edge{
+		logger:  logger,
+		regions: regions,
+	}, nil
+}
+
+// MockEdge creates a Cloudflare Edge from arbitrary TCP addresses. Used for testing.
+func MockEdge(l *logrus.Logger, addrs []*net.TCPAddr) *Edge {
+	logger := l.WithField("subsystem", subsystem)
+	regions := allregions.NewNoResolve(addrs)
+	return &Edge{
+		logger:  logger,
+		regions: regions,
+	}
+}
+
+// ------------------------------------
+// Methods
+// ------------------------------------
+
+// GetAddrForRPC gives this connection an edge Addr.
+func (ed *Edge) GetAddrForRPC() (*net.TCPAddr, error) {
+	ed.Lock()
+	defer ed.Unlock()
+	addr := ed.regions.GetAnyAddress()
+	if addr == nil {
+		return nil, errNoAddressesLeft
+	}
+	return addr, nil
+}
+
+// GetAddr gives this proxy connection an edge Addr. Prefer Addrs this connection has already used.
+func (ed *Edge) GetAddr(connID int) (*net.TCPAddr, error) {
+	ed.Lock()
+	defer ed.Unlock()
+	logger := ed.logger.WithFields(logrus.Fields{
+		"connID":   connID,
+		"function": "GetAddr",
+	})
+
+	// If this connection has already used an edge addr, return it.
+	if addr := ed.regions.AddrUsedBy(connID); addr != nil {
+		logger.Debug("Returning same address back to proxy connection")
+		return addr, nil
+	}
+
+	// Otherwise, give it an unused one
+	addr := ed.regions.GetUnusedAddr(nil, connID)
+	if addr == nil {
+		logger.Debug("No addresses left to give proxy connection")
+		return nil, errNoAddressesLeft
+	}
+	logger.Debug("Giving connection its new address")
+	return addr, nil
+}
+
+// GetDifferentAddr gives back the proxy connection's edge Addr and uses a new one.
+func (ed *Edge) GetDifferentAddr(connID int) (*net.TCPAddr, error) {
+	ed.Lock()
+	defer ed.Unlock()
+	logger := ed.logger.WithFields(logrus.Fields{
+		"connID":   connID,
+		"function": "GetDifferentAddr",
+	})
+
+	oldAddr := ed.regions.AddrUsedBy(connID)
+	if oldAddr != nil {
+		ed.regions.GiveBack(oldAddr)
+	}
+	addr := ed.regions.GetUnusedAddr(oldAddr, connID)
+	if addr == nil {
+		logger.Debug("No addresses left to give proxy connection")
+		return nil, errNoAddressesLeft
+	}
+	logger.Debug("Giving connection its new address")
+	return addr, nil
+}
+
+// AvailableAddrs returns how many unused addresses there are left.
+func (ed *Edge) AvailableAddrs() int {
+	ed.Lock()
+	defer ed.Unlock()
+	return ed.regions.AvailableAddrs()
+}
+
+// GiveBack the address so that other connections can use it.
+// Returns true if the address is in this edge.
+func (ed *Edge) GiveBack(addr *net.TCPAddr) bool {
+	ed.Lock()
+	defer ed.Unlock()
+	ed.logger.WithField("function", "GiveBack").Debug("Address now unused")
+	return ed.regions.GiveBack(addr)
+}