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

edgediscovery/allregions/regions.go

@@ -0,0 +1,118 @@
+package allregions
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/sirupsen/logrus"
+)
+
+// Regions stores Cloudflare edge network IPs, partitioned into two regions.
+// This is NOT thread-safe. Users of this package should use it with a lock.
+type Regions struct {
+	region1 Region
+	region2 Region
+}
+
+// ------------------------------------
+// Constructors
+// ------------------------------------
+
+// ResolveEdge resolves the Cloudflare edge, returning all regions discovered.
+func ResolveEdge(logger *logrus.Entry) (*Regions, error) {
+	addrLists, err := edgeDiscovery(logger)
+	if err != nil {
+		return nil, err
+	}
+	if len(addrLists) < 2 {
+		return nil, fmt.Errorf("expected at least 2 Cloudflare Regions regions, but SRV only returned %v", len(addrLists))
+	}
+	return &Regions{
+		region1: NewRegion(addrLists[0]),
+		region2: NewRegion(addrLists[1]),
+	}, nil
+}
+
+// StaticEdge creates a list of edge addresses from the list of hostnames.
+// Mainly used for testing connectivity.
+func StaticEdge(hostnames []string) (*Regions, error) {
+	addrs, err := ResolveAddrs(hostnames)
+	if err != nil {
+		return nil, err
+	}
+	return NewNoResolve(addrs), nil
+}
+
+// NewNoResolve doesn't resolve the edge. Instead it just uses the given addresses.
+// You probably only need this for testing.
+func NewNoResolve(addrs []*net.TCPAddr) *Regions {
+	region1 := make([]*net.TCPAddr, 0)
+	region2 := make([]*net.TCPAddr, 0)
+	for i, v := range addrs {
+		if i%2 == 0 {
+			region1 = append(region1, v)
+		} else {
+			region2 = append(region2, v)
+		}
+	}
+
+	return &Regions{
+		region1: NewRegion(region1),
+		region2: NewRegion(region2),
+	}
+}
+
+// ------------------------------------
+// Methods
+// ------------------------------------
+
+// GetAnyAddress returns an arbitrary address from the larger region.
+func (rs *Regions) GetAnyAddress() *net.TCPAddr {
+	if rs.region1.AvailableAddrs() > rs.region2.AvailableAddrs() {
+		return rs.region1.GetAnyAddress()
+	}
+	return rs.region2.GetAnyAddress()
+}
+
+// AddrUsedBy finds the address used by the given connection.
+// Returns nil if the connection isn't using an address.
+func (rs *Regions) AddrUsedBy(connID int) *net.TCPAddr {
+	if addr := rs.region1.AddrUsedBy(connID); addr != nil {
+		return addr
+	}
+	return rs.region2.AddrUsedBy(connID)
+}
+
+// GetUnusedAddr gets an unused addr from the edge, excluding the given addr. Prefer to use addresses
+// evenly across both regions.
+func (rs *Regions) GetUnusedAddr(excluding *net.TCPAddr, connID int) *net.TCPAddr {
+	var addr *net.TCPAddr
+	if rs.region1.AvailableAddrs() > rs.region2.AvailableAddrs() {
+		addr = rs.region1.GetUnusedIP(excluding)
+		rs.region1.Use(addr, connID)
+	} else {
+		addr = rs.region2.GetUnusedIP(excluding)
+		rs.region2.Use(addr, connID)
+	}
+
+	if addr == nil {
+		return nil
+	}
+
+	// Mark the address as used and return it
+	return addr
+}
+
+// AvailableAddrs returns how many edge addresses aren't used.
+func (rs *Regions) AvailableAddrs() int {
+	return rs.region1.AvailableAddrs() + rs.region2.AvailableAddrs()
+}
+
+// GiveBack the address so that other connections can use it.
+// Returns true if the address is in this edge.
+func (rs *Regions) GiveBack(addr *net.TCPAddr) bool {
+	if found := rs.region1.GiveBack(addr); found {
+		return found
+	}
+	return rs.region2.GiveBack(addr)
+}