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|
package apns
import (
"crypto/tls"
"errors"
"net"
"strings"
"time"
)
var _ APNSClient = &Client{}
// APNSClient is an APNS client.
type APNSClient interface {
ConnectAndWrite(resp *PushNotificationResponse, payload []byte) (err error)
Send(pn *PushNotification) (resp *PushNotificationResponse)
}
// Client contains the fields necessary to communicate
// with Apple, such as the gateway to use and your
// certificate contents.
//
// You'll need to provide your own CertificateFile
// and KeyFile to send notifications. Ideally, you'll
// just set the CertificateFile and KeyFile fields to
// a location on drive where the certs can be loaded,
// but if you prefer you can use the CertificateBase64
// and KeyBase64 fields to store the actual contents.
type Client struct {
Gateway string
CertificateFile string
CertificateBase64 string
KeyFile string
KeyBase64 string
}
// BareClient can be used to set the contents of your
// certificate and key blocks manually.
func BareClient(gateway, certificateBase64, keyBase64 string) (c *Client) {
c = new(Client)
c.Gateway = gateway
c.CertificateBase64 = certificateBase64
c.KeyBase64 = keyBase64
return
}
// NewClient assumes you'll be passing in paths that
// point to your certificate and key.
func NewClient(gateway, certificateFile, keyFile string) (c *Client) {
c = new(Client)
c.Gateway = gateway
c.CertificateFile = certificateFile
c.KeyFile = keyFile
return
}
// Send connects to the APN service and sends your push notification.
// Remember that if the submission is successful, Apple won't reply.
func (client *Client) Send(pn *PushNotification) (resp *PushNotificationResponse) {
resp = new(PushNotificationResponse)
payload, err := pn.ToBytes()
if err != nil {
resp.Success = false
resp.Error = err
return
}
err = client.ConnectAndWrite(resp, payload)
if err != nil {
resp.Success = false
resp.Error = err
return
}
resp.Success = true
resp.Error = nil
return
}
// ConnectAndWrite establishes the connection to Apple and handles the
// transmission of your push notification, as well as waiting for a reply.
//
// In lieu of a timeout (which would be available in Go 1.1)
// we use a timeout channel pattern instead. We start two goroutines,
// one of which just sleeps for TimeoutSeconds seconds, while the other
// waits for a response from the Apple servers.
//
// Whichever channel puts data on first is the "winner". As such, it's
// possible to get a false positive if Apple takes a long time to respond.
// It's probably not a deal-breaker, but something to be aware of.
func (client *Client) ConnectAndWrite(resp *PushNotificationResponse, payload []byte) (err error) {
var cert tls.Certificate
if len(client.CertificateBase64) == 0 && len(client.KeyBase64) == 0 {
// The user did not specify raw block contents, so check the filesystem.
cert, err = tls.LoadX509KeyPair(client.CertificateFile, client.KeyFile)
} else {
// The user provided the raw block contents, so use that.
cert, err = tls.X509KeyPair([]byte(client.CertificateBase64), []byte(client.KeyBase64))
}
if err != nil {
return err
}
gatewayParts := strings.Split(client.Gateway, ":")
conf := &tls.Config{
Certificates: []tls.Certificate{cert},
ServerName: gatewayParts[0],
}
conn, err := net.Dial("tcp", client.Gateway)
if err != nil {
return err
}
defer conn.Close()
tlsConn := tls.Client(conn, conf)
err = tlsConn.Handshake()
if err != nil {
return err
}
defer tlsConn.Close()
_, err = tlsConn.Write(payload)
if err != nil {
return err
}
// Create one channel that will serve to handle
// timeouts when the notification succeeds.
timeoutChannel := make(chan bool, 1)
go func() {
time.Sleep(time.Second * TimeoutSeconds)
timeoutChannel <- true
}()
// This channel will contain the binary response
// from Apple in the event of a failure.
responseChannel := make(chan []byte, 1)
go func() {
buffer := make([]byte, 6, 6)
tlsConn.Read(buffer)
responseChannel <- buffer
}()
// First one back wins!
// The data structure for an APN response is as follows:
//
// command -> 1 byte
// status -> 1 byte
// identifier -> 4 bytes
//
// The first byte will always be set to 8.
select {
case r := <-responseChannel:
resp.Success = false
resp.AppleResponse = ApplePushResponses[r[1]]
err = errors.New(resp.AppleResponse)
case <-timeoutChannel:
resp.Success = true
}
return err
}
|
