Added draft SMS support.

api/modem/sms/errors.go

@@ -0,0 +1,69 @@
+package sms
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func DecodeError(code int) string {
+	switch code {
+	case 300:
+		return "ME failure"
+	case 301:
+		return "SMS service of ME reserved"
+	case 302:
+		return "Operation not allowed"
+	case 303:
+		return "Operation not supported"
+	case 304:
+		return "Invalid PDU mode parameter"
+	case 305:
+		return "Invalid text mode parameter"
+	case 310:
+		return "SIM not inserted"
+	case 311:
+		return "SIM PIN required"
+	case 312:
+		return "PH-SIM PIN required"
+	case 313:
+		return "SIM failure"
+	case 314:
+		return "SIM busy"
+	case 315:
+		return "SIM wrong"
+	case 316:
+		return "SIM PUK required"
+	case 317:
+		return "SIM PIN2 required"
+	case 318:
+		return "SIM PUK2 required"
+	case 320:
+		return "Memory failure"
+	case 321:
+		return "Invalid memory index"
+	case 322:
+		return "Memory full"
+	case 330:
+		return "SMSC address unknown"
+	case 331:
+		return "No network service"
+	case 332:
+		return "Network timeout"
+	case 340:
+		return "NO +CNMA ACK EXPECTED"
+	case 341:
+		return "Buffer overflow"
+	case 342:
+		return "SMS size more than expected"
+	case 500:
+		return "Unknown error"
+	}
+	return "UNDEFINED ERROR CODE"
+}
+
+func GetError(msg []byte) (int, error) {
+	if len(msg) >= len("+CMS ERROR: ")+3 && string(msg[:len("+CMS ERROR: ")]) == "+CMS ERROR: " {
+		return strconv.Atoi(string(msg[len("+CMS ERROR: ") : len("+CMS ERROR: ")+3]))
+	}
+	return 0, fmt.Errorf("failed to parse error")
+}

api/modem/sms/sms.go

@@ -0,0 +1,61 @@
+package sms
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"strings"
+
+	"github.com/CGSG-2021-AE4/modem-test/api/modem/at"
+)
+
+type dialer struct {
+	logger *log.Logger
+	port   at.Port
+}
+
+type Dialer interface {
+	Init() error
+	Send(number, msg string) error
+	ReadNew() ([]string, error)
+	io.Closer
+}
+
+func (d *dialer) Init() error {
+	// Ensure serial port
+	if !d.port.IsConnected() {
+		return fmt.Errorf("serial port is not connected")
+	}
+	// Ensure text format
+	if resp, err := d.port.Send("AT+CMGF=1"); err != nil || !resp.Check() {
+		if err != nil {
+			return fmt.Errorf("AT+CMGF=1 request: %w", err)
+		}
+		return fmt.Errorf("failed to set SMS format")
+	}
+	return nil
+}
+
+func (d *dialer) Send(number, msg string) error {
+	cmd := fmt.Sprintf("AT+CMGS=\"%s\"\r%s%c", number, msg, 26)
+	if resp, err := d.port.Send(cmd); err != nil || !resp.Check() {
+		if err != nil {
+			return fmt.Errorf("AT+CGMS= request: %w", err)
+		}
+		if errCode, err := GetError(resp.Bytes()); err != nil {
+			return fmt.Errorf("failed to send with SMS error: %s", DecodeError(errCode))
+		}
+		return fmt.Errorf("failed to send SMS")
+	}
+	return nil
+}
+
+// Reads all new messages
+func (d *dialer) ReadNew() ([]string, error) {
+	resp, err := d.port.Send("AT+CMGL")
+	if err != nil {
+		return nil, fmt.Errorf("AT+CMGL request: %w", err)
+	}
+	msgs := strings.Split(strings.Replace(string(resp), "\r", "", -1), "\n")
+	return msgs, nil // TODO
+}