feat(darwin): add L2CAP support

gap.go

@@ -136,6 +136,7 @@ type GAPDevice interface {
 	RequestConnectionParams(params ConnectionParams) error
 	Connected() (bool, error)
 	Disconnect() error
+	OpenL2CAPChannel(psm L2CAPPSM) (*L2CAPConn, error)
 }
 
 // ScanResult contains information from when an advertisement packet was

gap_darwin.go

@@ -101,7 +101,8 @@ type deviceInternal struct {
 	servicesChan chan error
 	charsChan    chan error
 
-	services map[UUID]DeviceService
+	services  map[UUID]DeviceService
+	l2capChan chan l2capResult
 }
 
 // Connect starts a connection attempt to the given peripheral device address.
@@ -256,3 +257,10 @@ func (pd *peripheralDelegate) DidWriteValueForCharacteristic(_ cbgo.Peripheral,
 		}
 	}
 }
+
+// DidOpenL2CAPChannel is called when an L2CAP channel has been opened.
+func (pd *peripheralDelegate) DidOpenL2CAPChannel(prph cbgo.Peripheral, channel cbgo.L2CAPChannel, err error) {
+	if pd.d.l2capChan != nil {
+		pd.d.l2capChan <- l2capResult{channel: channel, err: err}
+	}
+}

go.mod

@@ -7,8 +7,8 @@ require (
 	github.com/godbus/dbus/v5 v5.1.0
 	github.com/saltosystems/winrt-go v0.0.0-20240509164145-4f7860a3bd2b
 	github.com/soypat/cyw43439 v0.0.0-20250505012923-830110c8f4af
-	github.com/tinygo-org/cbgo v0.0.4
-	golang.org/x/crypto v0.12.0
+	github.com/tinygo-org/cbgo v0.0.5-0.20260404133704-78b73a9c8e7e
+	golang.org/x/crypto v0.26.0
 	tinygo.org/x/drivers v0.33.0
 	tinygo.org/x/tinyfont v0.6.0
 	tinygo.org/x/tinyterm v0.5.0
@@ -20,6 +20,6 @@ require (
 	github.com/soypat/seqs v0.0.0-20250124201400-0d65bc7c1710 // indirect
 	github.com/tinygo-org/pio v0.2.0 // indirect
 	golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d // indirect
-	golang.org/x/sys v0.11.0 // indirect
-	golang.org/x/term v0.11.0 // indirect
+	golang.org/x/sys v0.23.0 // indirect
+	golang.org/x/term v0.23.0 // indirect
 )

go.sum

@@ -5,6 +5,7 @@ github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
 github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
 github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
 github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
@@ -24,21 +25,81 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.5 h1:s5PTfem8p8EbKQOctVV53k6jCJt3UX4IEJzwh+C324Q=
 github.com/stretchr/testify v1.7.5/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/tinygo-org/cbgo v0.0.4 h1:3D76CRYbH03Rudi8sEgs/YO0x3JIMdyq8jlQtk/44fU=
-github.com/tinygo-org/cbgo v0.0.4/go.mod h1:7+HgWIHd4nbAz0ESjGlJ1/v9LDU1Ox8MGzP9mah/fLk=
+github.com/tinygo-org/cbgo v0.0.5-0.20260404133704-78b73a9c8e7e h1:6rWS9GYjNL5fM9R57DO9sm0k29i0083HhSfJCzEmq2Q=
+github.com/tinygo-org/cbgo v0.0.5-0.20260404133704-78b73a9c8e7e/go.mod h1:FruLOLNWPVyKyydTExa3RiPBjlAiorVsfRizhv4evoM=
 github.com/tinygo-org/pio v0.2.0 h1:vo3xa6xDZ2rVtxrks/KcTZHF3qq4lyWOntvEvl2pOhU=
 github.com/tinygo-org/pio v0.2.0/go.mod h1:LU7Dw00NJ+N86QkeTGjMLNkYcEYMor6wTDpTCu0EaH8=
-golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk=
-golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.13.0/go.mod h1:y6Z2r+Rw4iayiXXAIxJIDAJ1zMW4yaTpebo8fPOliYc=
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 golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=
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 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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l2cap.go

@@ -0,0 +1,13 @@
+package bluetooth
+
+import "io"
+
+// L2CAPPSM represents an L2CAP Protocol/Service Multiplexer identifier.
+type L2CAPPSM = uint16
+
+// L2CAPChannel is the common interface implemented by L2CAPConn on all platforms.
+type L2CAPChannel interface {
+	io.ReadWriteCloser
+	// PSM returns the Protocol/Service Multiplexer identifier for this channel.
+	PSM() L2CAPPSM
+}

l2cap_darwin.go

@@ -0,0 +1,143 @@
+package bluetooth
+
+import (
+	"errors"
+	"io"
+	"runtime"
+	"sync"
+	"time"
+
+	"github.com/tinygo-org/cbgo"
+)
+
+// l2capResult is used internally to communicate the result of an L2CAP channel
+// open operation from the delegate callback to the calling goroutine.
+type l2capResult struct {
+	channel cbgo.L2CAPChannel
+	err     error
+}
+
+// L2CAPConn represents an L2CAP Connection-Oriented Channel connection.
+// It implements io.ReadWriteCloser for bidirectional communication.
+type L2CAPConn struct {
+	channel cbgo.L2CAPChannel
+	mu      sync.Mutex
+	closed  bool
+}
+
+var _ L2CAPChannel = (*L2CAPConn)(nil)
+
+// OpenL2CAPChannel opens an L2CAP Connection-Oriented Channel to the
+// connected peripheral. The PSM (Protocol/Service Multiplexer) identifies the
+// L2CAP service to connect to on the remote device.
+//
+// The device must already be connected via Connect before calling this method.
+func (d Device) OpenL2CAPChannel(psm L2CAPPSM) (*L2CAPConn, error) {
+	ch := make(chan l2capResult, 1)
+	d.l2capChan = ch
+	defer func() { d.l2capChan = nil }()
+
+	d.prph.OpenL2CAPChannel(psm)
+
+	select {
+	case result := <-ch:
+		if result.err != nil {
+			return nil, result.err
+		}
+		return &L2CAPConn{
+			channel: result.channel,
+		}, nil
+	case <-time.NewTimer(30 * time.Second).C:
+		return nil, errors.New("bluetooth: timeout on OpenL2CAPChannel")
+	}
+}
+
+// Read reads data from the L2CAP channel. It blocks until data is available,
+// the channel is closed locally, or the remote end closes the stream (EOF).
+func (c *L2CAPConn) Read(p []byte) (int, error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	for {
+		c.mu.Lock()
+		if c.closed {
+			c.mu.Unlock()
+			return 0, io.ErrClosedPipe
+		}
+		c.mu.Unlock()
+
+		n := c.channel.Read(p)
+		if n < 0 {
+			return 0, errors.New("bluetooth: L2CAP read error")
+		}
+		if n > 0 {
+			return n, nil
+		}
+
+		// c.channel.Read returns 0 in two cases:
+		//  - hasBytesAvailable was false → no data yet, retry.
+		//  - hasBytesAvailable was true but NSInputStream read returned 0 → EOF.
+		// Distinguish them by checking HasBytesAvailable after a 0-byte read.
+		if !c.channel.HasBytesAvailable() {
+			// No data available yet, yield and retry.
+			runtime.Gosched()
+			continue
+		}
+		// The stream reported bytes available yet Read returned 0:
+		// the input stream has reached end-of-stream.
+		return 0, io.EOF
+	}
+}
+
+// Write writes data to the L2CAP channel. It blocks until all data has been
+// written or the channel is closed.
+func (c *L2CAPConn) Write(p []byte) (int, error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	total := 0
+	for total < len(p) {
+		c.mu.Lock()
+		if c.closed {
+			c.mu.Unlock()
+			return total, io.ErrClosedPipe
+		}
+		c.mu.Unlock()
+
+		// Output stream not ready yet, yield and retry.
+		if !c.channel.HasSpaceAvailable() {
+			runtime.Gosched()
+			continue
+		}
+
+		n := c.channel.Write(p[total:])
+		if n < 0 {
+			return total, errors.New("bluetooth: L2CAP write error")
+		}
+		if n > 0 {
+			total += n
+			continue
+		}
+	}
+	return total, nil
+}
+
+// Close closes the L2CAP channel.
+func (c *L2CAPConn) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return nil
+	}
+	c.closed = true
+	c.channel.Close()
+	return nil
+}
+
+// PSM returns the Protocol/Service Multiplexer identifier for this channel.
+func (c *L2CAPConn) PSM() L2CAPPSM {
+	return c.channel.PSM()
+}

l2cap_hci.go

@@ -164,3 +164,33 @@ func (l *l2cap) sendReq(handle uint16, data []byte) error {
 
 	return l.hci.sendAclPkt(handle, signalingCID, data)
 }
+
+// L2CAPConn represents an L2CAP Connection-Oriented Channel connection.
+type L2CAPConn struct{}
+
+var _ L2CAPChannel = (*L2CAPConn)(nil)
+
+// Read is not yet implemented on this platform.
+func (c *L2CAPConn) Read(p []byte) (int, error) {
+	return 0, errNotYetImplmented
+}
+
+// Write is not yet implemented on this platform.
+func (c *L2CAPConn) Write(p []byte) (int, error) {
+	return 0, errNotYetImplmented
+}
+
+// Close is not yet implemented on this platform.
+func (c *L2CAPConn) Close() error {
+	return errNotYetImplmented
+}
+
+// PSM is not yet implemented on this platform.
+func (c *L2CAPConn) PSM() L2CAPPSM {
+	return 0
+}
+
+// OpenL2CAPChannel is not yet implemented on this platform.
+func (d Device) OpenL2CAPChannel(psm L2CAPPSM) (*L2CAPConn, error) {
+	return nil, errNotYetImplmented
+}

l2cap_linux.go

@@ -0,0 +1,33 @@
+//go:build !baremetal
+
+package bluetooth
+
+// L2CAPConn represents an L2CAP Connection-Oriented Channel connection.
+type L2CAPConn struct{}
+
+var _ L2CAPChannel = (*L2CAPConn)(nil)
+
+// Read is not yet implemented on this platform.
+func (c *L2CAPConn) Read(p []byte) (int, error) {
+	return 0, errNotYetImplmented
+}
+
+// Write is not yet implemented on this platform.
+func (c *L2CAPConn) Write(p []byte) (int, error) {
+	return 0, errNotYetImplmented
+}
+
+// Close is not yet implemented on this platform.
+func (c *L2CAPConn) Close() error {
+	return errNotYetImplmented
+}
+
+// PSM is not yet implemented on this platform.
+func (c *L2CAPConn) PSM() L2CAPPSM {
+	return 0
+}
+
+// OpenL2CAPChannel is not yet implemented on this platform.
+func (d Device) OpenL2CAPChannel(psm L2CAPPSM) (*L2CAPConn, error) {
+	return nil, errNotYetImplmented
+}