cloudflared-mirror/edgediscovery/edgediscovery.go

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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.Debugf("Giving connection its new address %s", addr)
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")
// note: if oldAddr were not nil, it will become available on the next iteration
return nil, errNoAddressesLeft
}
logger.Debugf("Giving connection its new address %s", addr)
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)
}