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reuse listening connections for dialing
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| package libp2pquic | ||
|
|
||
| import ( | ||
| "net" | ||
| "sync" | ||
| "sync/atomic" | ||
|
|
||
| "github.com/vishvananda/netlink" | ||
| ) | ||
|
|
||
| type reuseConn struct { | ||
| net.PacketConn | ||
| refCount int32 // to be used as an atomic | ||
| } | ||
|
|
||
| func newReuseConn(conn net.PacketConn) *reuseConn { | ||
| return &reuseConn{PacketConn: conn} | ||
| } | ||
|
|
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| func (c *reuseConn) IncreaseCount() { atomic.AddInt32(&c.refCount, 1) } | ||
| func (c *reuseConn) DecreaseCount() { atomic.AddInt32(&c.refCount, -1) } | ||
| func (c *reuseConn) GetCount() int { return int(atomic.LoadInt32(&c.refCount)) } | ||
|
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| type reuse struct { | ||
| mutex sync.Mutex | ||
|
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| unicast map[string] /* IP.String() */ map[int] /* port */ *reuseConn | ||
| // global contains connections that are listening on 0.0.0.0 / :: | ||
| global map[int]*reuseConn | ||
| } | ||
|
|
||
| func newReuse() *reuse { | ||
| return &reuse{ | ||
| unicast: make(map[string]map[int]*reuseConn), | ||
| global: make(map[int]*reuseConn), | ||
| } | ||
| } | ||
|
|
||
| func (r *reuse) getSourceIPs(network string, raddr *net.UDPAddr) ([]net.IP, error) { | ||
| // Determine the source address that the kernel would use for this IP address. | ||
| // Note: This only works on Linux. | ||
| // On other OSes, this will return a netlink.ErrNotImplemetned. | ||
| routes, err := (&netlink.Handle{}).RouteGet(raddr.IP) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| ips := make([]net.IP, 0, len(routes)) | ||
| for _, route := range routes { | ||
| ips = append(ips, route.Src) | ||
| } | ||
| return ips, nil | ||
| } | ||
|
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| func (r *reuse) Dial(network string, raddr *net.UDPAddr) (*reuseConn, error) { | ||
| ips, err := r.getSourceIPs(network, raddr) | ||
| if err != nil && err != netlink.ErrNotImplemented { | ||
| return nil, err | ||
| } | ||
|
|
||
| r.mutex.Lock() | ||
| defer r.mutex.Unlock() | ||
|
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| conn, err := r.dialLocked(network, raddr, ips) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| conn.IncreaseCount() | ||
| return conn, nil | ||
| } | ||
|
|
||
| func (r *reuse) dialLocked(network string, raddr *net.UDPAddr, ips []net.IP) (*reuseConn, error) { | ||
| for _, ip := range ips { | ||
| // We already have at least one suitable connection... | ||
| if conns, ok := r.unicast[ip.String()]; ok { | ||
| // ... we don't care which port we're dialing from. Just use the first. | ||
| for _, c := range conns { | ||
| return c, nil | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Use a connection listening on 0.0.0.0 (or ::). | ||
| // Again, we don't care about the port number. | ||
| for _, conn := range r.global { | ||
| return conn, nil | ||
| } | ||
|
|
||
| // We don't have a connection that we can use for dialing. | ||
| // Dial a new connection from a random port. | ||
| var addr *net.UDPAddr | ||
| switch network { | ||
| case "udp4": | ||
| addr = &net.UDPAddr{IP: net.IPv4zero, Port: 0} | ||
| case "udp6": | ||
| addr = &net.UDPAddr{IP: net.IPv6zero, Port: 0} | ||
| } | ||
| conn, err := net.ListenUDP(network, addr) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| rconn := newReuseConn(conn) | ||
| r.global[conn.LocalAddr().(*net.UDPAddr).Port] = rconn | ||
| return rconn, nil | ||
| } | ||
|
|
||
| func (r *reuse) Listen(network string, laddr *net.UDPAddr) (*reuseConn, error) { | ||
| conn, err := net.ListenUDP(network, laddr) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| localAddr := conn.LocalAddr().(*net.UDPAddr) | ||
|
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||
| rconn := newReuseConn(conn) | ||
| rconn.IncreaseCount() | ||
|
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||
| r.mutex.Lock() | ||
| defer r.mutex.Unlock() | ||
|
|
||
| // Deal with listen on a global address | ||
| if laddr.IP.IsUnspecified() { | ||
| // The kernel already checked that the laddr is not already listen | ||
| // so we need not check here (when we create ListenUDP). | ||
| r.global[laddr.Port] = rconn | ||
| return rconn, err | ||
| } | ||
|
|
||
| // Deal with listen on a unicast address | ||
| if _, ok := r.unicast[localAddr.IP.String()]; !ok { | ||
| r.unicast[laddr.IP.String()] = make(map[int]*reuseConn) | ||
| } | ||
|
|
||
| // The kernel already checked that the laddr is not already listen | ||
| // so we need not check here (when we create ListenUDP). | ||
| r.unicast[laddr.IP.String()][localAddr.Port] = rconn | ||
| return rconn, err | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,79 @@ | ||
| package libp2pquic | ||
|
|
||
| import ( | ||
| "net" | ||
| "runtime" | ||
|
|
||
| . "github.com/onsi/ginkgo" | ||
| . "github.com/onsi/gomega" | ||
| ) | ||
|
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| var _ = Describe("Reuse", func() { | ||
| var reuse *reuse | ||
|
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| BeforeEach(func() { | ||
| reuse = newReuse() | ||
| }) | ||
|
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| It("creates a new global connection when listening on 0.0.0.0", func() { | ||
| addr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| conn, err := reuse.Listen("udp4", addr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(conn.GetCount()).To(Equal(1)) | ||
| }) | ||
|
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| It("creates a new global connection when listening on [::]", func() { | ||
| addr, err := net.ResolveUDPAddr("udp6", "[::]:1234") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| conn, err := reuse.Listen("udp6", addr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(conn.GetCount()).To(Equal(1)) | ||
| }) | ||
|
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||
| It("creates a new global connection when dialing", func() { | ||
| addr, err := net.ResolveUDPAddr("udp4", "1.1.1.1:1234") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| conn, err := reuse.Dial("udp4", addr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(conn.GetCount()).To(Equal(1)) | ||
| laddr := conn.LocalAddr().(*net.UDPAddr) | ||
| Expect(laddr.IP.String()).To(Equal("0.0.0.0")) | ||
| Expect(laddr.Port).ToNot(BeZero()) | ||
| }) | ||
|
|
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| It("reuses a connection it created for listening when dialing", func() { | ||
| // listen | ||
| addr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| lconn, err := reuse.Listen("udp4", addr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(lconn.GetCount()).To(Equal(1)) | ||
| // dial | ||
| raddr, err := net.ResolveUDPAddr("udp4", "1.1.1.1:1234") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| conn, err := reuse.Dial("udp4", raddr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(conn.GetCount()).To(Equal(2)) | ||
| }) | ||
|
|
||
| if runtime.GOOS == "linux" { | ||
| It("reuses a connection it created for listening on a specific interface", func() { | ||
| raddr, err := net.ResolveUDPAddr("udp4", "1.1.1.1:1234") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| ips, err := reuse.getSourceIPs("udp4", raddr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(ips).ToNot(BeEmpty()) | ||
| // listen | ||
| addr, err := net.ResolveUDPAddr("udp4", ips[0].String()+":0") | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| lconn, err := reuse.Listen("udp4", addr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(lconn.GetCount()).To(Equal(1)) | ||
| // dial | ||
| conn, err := reuse.Dial("udp4", raddr) | ||
| Expect(err).ToNot(HaveOccurred()) | ||
| Expect(conn.GetCount()).To(Equal(2)) | ||
| }) | ||
| } | ||
| }) |
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