Fix user data encoding for SMS

Use utf8.RuneCountInString to count characters

Author: corny

at.go

@@ -424,13 +424,11 @@ func (d *Device) SendSMS(text string, address sms.PhoneNumber) (err error) {
 		VPFormat: sms.ValidityPeriodFormats.Relative,
 		VP:       sms.ValidityPeriod(24 * time.Hour * 4),
 	}
-	for _, w := range text {
-		// detected a double-width char
-		if w > 1 {
-			msg.Encoding = sms.Encodings.UCS2
-			break
-		}
+
+	if !pdu.Is7BitEncodable(text) {
+		msg.Encoding = sms.Encodings.UCS2
 	}
+
 	n, octets, err := msg.PDU()
 	if err != nil {
 		return

sms/sms.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"errors"
 	"io"
+	"unicode/utf8"
 
 	"github.com/xlab/at/pdu"
 )
@@ -119,20 +120,11 @@ func (s *Message) encodeDeliver(buf *bytes.Buffer) (n int, err error) {
 	sms.ProtocolIdentifier = 0x00 // Short Message Type 0
 	sms.DataCodingScheme = byte(s.Encoding)
 	sms.ServiceCentreTimestamp = s.ServiceCenterTime.PDU()
-
-	var userData []byte
-	switch s.Encoding {
-	case Encodings.Gsm7Bit, Encodings.Gsm7Bit_2:
-		userData = pdu.Encode7Bit(s.Text)
-		sms.UserDataLength = byte(len(s.Text))
-	case Encodings.UCS2:
-		userData = pdu.EncodeUcs2(s.Text)
-		sms.UserDataLength = byte(len(userData))
-	default:
-		return 0, ErrUnknownEncoding
+	sms.UserData, sms.UserDataLength, err = s.encodedUserData()
+	if err != nil {
+		return 0, err
 	}
 
-	sms.UserData = userData
 	return buf.Write(sms.Bytes())
 }
 
@@ -165,19 +157,10 @@ func (s *Message) encodeSubmit(buf *bytes.Buffer) (n int, err error) {
 		return 0, ErrNonRelative
 	}
 
-	var userData []byte
-	switch s.Encoding {
-	case Encodings.Gsm7Bit, Encodings.Gsm7Bit_2:
-		userData = pdu.Encode7Bit(s.Text)
-		sms.UserDataLength = byte(len(s.Text))
-	case Encodings.UCS2:
-		userData = pdu.EncodeUcs2(s.Text)
-		sms.UserDataLength = byte(len(userData))
-	default:
-		return 0, ErrUnknownEncoding
+	sms.UserData, sms.UserDataLength, err = s.encodedUserData()
+	if err != nil {
+		return 0, err
 	}
-
-	sms.UserData = userData
 	return buf.Write(sms.Bytes())
 }
 
@@ -202,20 +185,11 @@ func (s *Message) encodeStatusReport(buf *bytes.Buffer) (n int, err error) {
 	sms.ServiceCentreTimestamp = s.ServiceCenterTime.PDU()
 	sms.DischargeTimestamp = s.DischargeTime.PDU()
 	sms.Status = byte(s.Status)
-
-	var userData []byte
-	switch s.Encoding {
-	case Encodings.Gsm7Bit, Encodings.Gsm7Bit_2:
-		userData = pdu.Encode7Bit(s.Text)
-		sms.UserDataLength = byte(len(s.Text))
-	case Encodings.UCS2:
-		userData = pdu.EncodeUcs2(s.Text)
-		sms.UserDataLength = byte(len(userData))
-	default:
-		return 0, ErrUnknownEncoding
+	sms.UserData, sms.UserDataLength, err = s.encodedUserData()
+	if err != nil {
+		return 0, err
 	}
 
-	sms.UserData = userData
 	return buf.Write(sms.Bytes())
 }
 
@@ -345,6 +319,21 @@ func (s *Message) decodeStatusReport(data []byte) (n int, err error) {
 	return n, err
 }
 
+func (s *Message) encodedUserData() (userData []byte, length byte, err error) {
+	switch s.Encoding {
+	case Encodings.Gsm7Bit, Encodings.Gsm7Bit_2:
+		userData = pdu.Encode7Bit(s.Text)
+		length = byte(utf8.RuneCountInString(s.Text))
+	case Encodings.UCS2:
+		userData = pdu.EncodeUcs2(s.Text)
+		length = byte(len(userData))
+	default:
+		err = ErrUnknownEncoding
+	}
+
+	return
+}
+
 func (s *Message) decodeUserData(data []byte, dataLen byte) (err error) {
 	switch s.Encoding {
 	case Encodings.Gsm7Bit, Encodings.Gsm7Bit_2:

sms/sms_test.go

@@ -20,8 +20,8 @@ var (
 		"003200200440043004370430002E0020041F043E0441043B04350434043D043804390020002D" +
 		"002000200032003600200438044E043D044F00200432002000320031003A00330035"
 
-	pduDeliverGsm7   = "07919762020033F1040B919762995696F0000041606291401561046379180E"
-	pduSubmitGsm7    = "07919762020033F111000B919762995696F00000AA046379180E"
+	pduDeliverGsm7   = "07919762020033F1040B919762995696F0000041606291401561066379180E8200"
+	pduSubmitGsm7    = "07919762020033F111000B919762995696F00000AA066379180E8200"
 	pduDeliverGsm7_2 = "0791551010010201040D91551699296568F80011719022124215293DD4B71C5E26BF" +
 		"41D3E6145476D3E5E573BD0C82BF40B59A2D96CBE564351BCE8603A164319D8CA6ABD540E432482673C172AED82DE502"
 
@@ -38,7 +38,7 @@ var (
 		ServiceCenterTime:    parseTimestamp("2014-06-26T21:36:30+04:00"),
 	}
 	smsDeliverGsm7 = Message{
-		Text:                 "crap",
+		Text:                 "crap Δ",
 		Encoding:             Encodings.Gsm7Bit,
 		Type:                 MessageTypes.Deliver,
 		Address:              "+79269965690",
@@ -63,7 +63,7 @@ var (
 		VPFormat:             ValidityPeriodFormats.Relative,
 	}
 	smsSubmitGsm7 = Message{
-		Text:                 "crap",
+		Text:                 "crap Δ",
 		Encoding:             Encodings.Gsm7Bit,
 		Type:                 MessageTypes.Submit,
 		Address:              "+79269965690",