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twilio.go
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twilio.go
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package twilio
/*
* Handler for Twilio channels, see https://www.twilio.com/docs/api
*/
import (
"bytes"
"context"
"crypto/hmac"
"crypto/sha1"
"encoding/base64"
"fmt"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
"github.com/buger/jsonparser"
"github.com/sirupsen/logrus"
"github.com/nyaruka/courier"
"github.com/nyaruka/courier/handlers"
"github.com/nyaruka/courier/utils"
"github.com/nyaruka/gocommon/urns"
"github.com/pkg/errors"
)
const configAccountSID = "account_sid"
const configMessagingServiceSID = "messaging_service_sid"
const configSendURL = "send_url"
const twSignatureHeader = "X-Twilio-Signature"
var maxMsgLength = 1600
var sendURL = "https://api.twilio.com/2010-04-01/Accounts"
// error code twilio returns when a contact has sent "stop"
const errorStopped = 21610
type handler struct {
handlers.BaseHandler
ignoreDeliveryReports bool
}
// NewHandler returns a new TwilioHandler ready to be registered
func NewHandler(channelType string, name string) courier.ChannelHandler {
return &handler{handlers.NewBaseHandler(courier.ChannelType(channelType), name), false}
}
func init() {
courier.RegisterHandler(NewHandler("T", "Twilio"))
courier.RegisterHandler(NewHandler("TMS", "Twilio Messaging Service"))
}
// Initialize is called by the engine once everything is loaded
func (h *handler) Initialize(s courier.Server) error {
h.SetServer(s)
// save whether we should ignore delivery reports
h.ignoreDeliveryReports = s.Config().IgnoreDeliveryReports
err := s.AddHandlerRoute(h, "POST", "receive", h.ReceiveMessage)
if err != nil {
return err
}
return s.AddHandlerRoute(h, "POST", "status", h.StatusMessage)
}
type twMessage struct {
MessageSID string `validate:"required"`
AccountSID string `validate:"required"`
From string `validate:"required"`
FromCountry string
To string `validate:"required"`
ToCountry string
Body string
NumMedia int
}
type twStatus struct {
MessageSID string `validate:"required"`
MessageStatus string `validate:"required"`
ErrorCode string
}
var twStatusMapping = map[string]courier.MsgStatusValue{
"queued": courier.MsgSent,
"failed": courier.MsgFailed,
"sent": courier.MsgSent,
"delivered": courier.MsgDelivered,
"undelivered": courier.MsgFailed,
}
// ReceiveMessage is our HTTP handler function for incoming messages
func (h *handler) ReceiveMessage(ctx context.Context, channel courier.Channel, w http.ResponseWriter, r *http.Request) ([]courier.Event, error) {
err := h.validateSignature(channel, r)
if err != nil {
return nil, err
}
// get our params
twMsg := &twMessage{}
err = handlers.DecodeAndValidateForm(twMsg, r)
if err != nil {
return nil, err
}
// create our URN
urn := urns.NewTelURNForCountry(twMsg.From, twMsg.FromCountry)
if twMsg.Body != "" {
// Twilio sometimes sends concatenated sms as base64 encoded MMS
twMsg.Body = handlers.DecodePossibleBase64(twMsg.Body)
}
// build our msg
msg := h.Backend().NewIncomingMsg(channel, urn, twMsg.Body).WithExternalID(twMsg.MessageSID)
// process any attached media
for i := 0; i < twMsg.NumMedia; i++ {
mediaURL := r.PostForm.Get(fmt.Sprintf("MediaUrl%d", i))
msg.WithAttachment(mediaURL)
}
// and finally queue our message
err = h.Backend().WriteMsg(ctx, msg)
if err != nil {
return nil, err
}
return []courier.Event{msg}, h.writeReceiveSuccess(ctx, w, r, msg)
}
// StatusMessage is our HTTP handler function for status updates
func (h *handler) StatusMessage(ctx context.Context, channel courier.Channel, w http.ResponseWriter, r *http.Request) ([]courier.Event, error) {
err := h.validateSignature(channel, r)
if err != nil {
return nil, err
}
// get our params
twStatus := &twStatus{}
err = handlers.DecodeAndValidateForm(twStatus, r)
if err != nil {
return nil, err
}
msgStatus, found := twStatusMapping[twStatus.MessageStatus]
if !found {
return nil, courier.WriteAndLogRequestError(ctx, w, r, channel, fmt.Errorf("unknown status '%s', must be one of 'queued', 'failed', 'sent', 'delivered', or 'undelivered'", twStatus.MessageStatus))
}
// if we are ignoring delivery reports and this isn't failed then move on
if h.ignoreDeliveryReports && msgStatus != courier.MsgFailed {
return nil, courier.WriteAndLogRequestIgnored(ctx, w, r, channel, "ignoring non error delivery report")
}
// if the message id was passed explicitely, use that
var status courier.MsgStatus
idString := r.URL.Query().Get("id")
if idString != "" {
msgID, err := strconv.ParseInt(idString, 10, 64)
if err != nil {
logrus.WithError(err).WithField("id", idString).Error("error converting twilio callback id to integer")
} else {
status = h.Backend().NewMsgStatusForID(channel, courier.NewMsgID(msgID), msgStatus)
}
}
// if we have no status, then build it from the external (twilio) id
if status == nil {
status = h.Backend().NewMsgStatusForExternalID(channel, twStatus.MessageSID, msgStatus)
}
// write our status
err = h.Backend().WriteMsgStatus(ctx, status)
if err != nil {
return nil, err
}
return []courier.Event{status}, courier.WriteStatusSuccess(ctx, w, r, []courier.MsgStatus{status})
}
// SendMsg sends the passed in message, returning any error
func (h *handler) SendMsg(ctx context.Context, msg courier.Msg) (courier.MsgStatus, error) {
// build our callback URL
callbackDomain := msg.Channel().CallbackDomain(h.Server().Config().Domain)
callbackURL := fmt.Sprintf("https://%s/c/%s/%s/status?id=%d&action=callback", callbackDomain, strings.ToLower(msg.Channel().ChannelType().String()), msg.Channel().UUID(), msg.ID().Int64)
accountSID := msg.Channel().StringConfigForKey(configAccountSID, "")
if accountSID == "" {
return nil, fmt.Errorf("missing account sid for twilio channel")
}
accountToken := msg.Channel().StringConfigForKey(courier.ConfigAuthToken, "")
if accountToken == "" {
return nil, fmt.Errorf("missing account auth token for twilio channel")
}
status := h.Backend().NewMsgStatusForID(msg.Channel(), msg.ID(), courier.MsgErrored)
parts := handlers.SplitMsg(msg.Text(), maxMsgLength)
for i, part := range parts {
// build our request
form := url.Values{
"To": []string{msg.URN().Path()},
"Body": []string{part},
"StatusCallback": []string{callbackURL},
}
// add any media URL to the first part
if len(msg.Attachments()) > 0 && i == 0 {
_, mediaURL := courier.SplitAttachment(msg.Attachments()[0])
form["MediaUrl"] = []string{mediaURL}
}
// set our from, either as a messaging service or from our address
serviceSID := msg.Channel().StringConfigForKey(configMessagingServiceSID, "")
if serviceSID != "" {
form["MessagingServiceSid"] = []string{serviceSID}
} else {
form["From"] = []string{msg.Channel().Address()}
}
baseSendURL := msg.Channel().StringConfigForKey(configSendURL, sendURL)
sendURL, err := utils.AddURLPath(baseSendURL, accountSID, "Messages.json")
if err != nil {
return nil, err
}
req, err := http.NewRequest(http.MethodPost, sendURL, strings.NewReader(form.Encode()))
req.SetBasicAuth(accountSID, accountToken)
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
req.Header.Set("Accept", "application/json")
rr, err := utils.MakeHTTPRequest(req)
// record our status and log
log := courier.NewChannelLogFromRR("Message Sent", msg.Channel(), msg.ID(), rr).WithError("Message Send Error", err)
status.AddLog(log)
// see if we can parse the error if we have one
if err != nil && rr.Body != nil {
errorCode, _ := jsonparser.GetInt([]byte(rr.Body), "code")
if errorCode != 0 {
if errorCode == errorStopped {
status.SetStatus(courier.MsgFailed)
h.Backend().StopMsgContact(ctx, msg)
}
log.WithError("Message Send Error", errors.Errorf("received error code from twilio '%d'", errorCode))
return status, nil
}
}
// fail if we received an error
if err != nil {
return status, nil
}
// grab the external id
externalID, err := jsonparser.GetString([]byte(rr.Body), "sid")
if err != nil {
log.WithError("Message Send Error", errors.Errorf("unable to get sid from body"))
return status, nil
}
status.SetStatus(courier.MsgWired)
// only save the first external id
if i == 0 {
status.SetExternalID(externalID)
}
}
return status, nil
}
// Twilio expects Twiml from a message receive request
func (h *handler) writeReceiveSuccess(ctx context.Context, w http.ResponseWriter, r *http.Request, msg courier.Msg) error {
courier.LogMsgReceived(r, msg)
w.Header().Set("Content-Type", "text/xml")
w.WriteHeader(200)
_, err := fmt.Fprint(w, `<?xml version="1.0" encoding="UTF-8"?><Response/>`)
return err
}
// see https://www.twilio.com/docs/api/security
func (h *handler) validateSignature(channel courier.Channel, r *http.Request) error {
actual := r.Header.Get(twSignatureHeader)
if actual == "" {
return fmt.Errorf("missing request signature")
}
if err := r.ParseForm(); err != nil {
return err
}
confAuth := channel.ConfigForKey(courier.ConfigAuthToken, "")
authToken, isStr := confAuth.(string)
if !isStr || authToken == "" {
return fmt.Errorf("invalid or missing auth token in config")
}
url := fmt.Sprintf("https://%s%s", r.Host, r.URL.RequestURI())
expected, err := twCalculateSignature(url, r.PostForm, authToken)
if err != nil {
return err
}
// compare signatures in way that isn't sensitive to a timing attack
if !hmac.Equal(expected, []byte(actual)) {
return fmt.Errorf("invalid request signature")
}
return nil
}
// see https://www.twilio.com/docs/api/security
func twCalculateSignature(url string, form url.Values, authToken string) ([]byte, error) {
var buffer bytes.Buffer
buffer.WriteString(url)
keys := make(sort.StringSlice, 0, len(form))
for k := range form {
keys = append(keys, k)
}
keys.Sort()
for _, k := range keys {
buffer.WriteString(k)
for _, v := range form[k] {
buffer.WriteString(v)
}
}
// hash with SHA1
mac := hmac.New(sha1.New, []byte(authToken))
mac.Write(buffer.Bytes())
hash := mac.Sum(nil)
// encode with Base64
encoded := make([]byte, base64.StdEncoding.EncodedLen(len(hash)))
base64.StdEncoding.Encode(encoded, hash)
return encoded, nil
}