Code cleanup

sdb.go

@@ -9,6 +9,71 @@ import (
 	"time"
 )
 
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Fprintf(os.Stderr,
+			"required argument missing\n")
+		os.Exit(1)
+	}
+
+	raw, err := ioutil.ReadFile(os.Args[1])
+	if err != nil {
+		fmt.Fprintf(os.Stderr,
+			"error reading \"%s\": %s\n",
+			os.Args[1], err.Error())
+	}
+
+	sdb, err := parseSDB(raw)
+	if err != nil {
+		fmt.Fprintf(os.Stderr,
+			"%s\n", err.Error())
+		os.Exit(1)
+	}
+
+	fmt.Printf("Protocol Revision: %d\n",
+		sdb.ProtocolRevision)
+	fmt.Printf("Message Length: %d\n",
+		sdb.Length)
+	for c, i := range sdb.Elements {
+		if c > 0 {
+			fmt.Println()
+		}
+		switch v := i.(type) {
+		case MOHeader:
+			fmt.Printf("\tMO Header IEI: %d\n",
+				v.IEI)
+			fmt.Printf("\tMO Header Length: %d\n",
+				v.Length)
+			fmt.Printf("\tMO Header CDR Reference: %d\n",
+				v.CDRReference)
+			fmt.Printf("\tMO Header IMEI: %s\n",
+				v.IMEI)
+			fmt.Printf("\tMO Header Status: %s (%d)\n",
+				v.StatusString(), v.Status)
+			fmt.Printf("\tMO Header MOMSN: %d\n",
+				v.MOMSN)
+			fmt.Printf("\tMO Header MTMSN: %d\n",
+				v.MTMSN)
+			fmt.Printf("\tMO Header Session Time: %s\n",
+				v.SessionTime().String())
+
+		case MOPayload:
+			fmt.Printf("\tMO Payload IEI: %d\n",
+				v.IEI)
+			fmt.Printf("\tMO Payload Length: %d\n",
+				v.Length)
+
+		case MOConfirmation:
+			fmt.Printf("\tMO Confirmation IEI: %d\n",
+				v.IEI)
+			fmt.Printf("\tMO Confirmation Length: %d\n",
+				v.Length)
+			fmt.Printf("\tMO Confirmation Status: %d\n",
+				v.Status)
+		}
+	}
+}
+
 type IridiumSDB struct {
 	ProtocolRevision byte
 	Length           uint16
@@ -76,32 +141,10 @@ type MOConfirmation struct {
 	Status byte
 }
 
-func main() {
+func parseSDB(raw []byte) (*IridiumSDB, error) {
-	if len(os.Args) < 2 {
-		fmt.Fprintf(os.Stderr,
-			"required argument missing\n")
-		os.Exit(1)
-	}
-
-	raw, err := ioutil.ReadFile(os.Args[1])
-	if err != nil {
-		fmt.Fprintf(os.Stderr,
-			"error reading \"%s\": %s\n",
-			os.Args[1], err.Error())
-	}
-
-	err = parseSDB(raw)
-	if err != nil {
-		fmt.Fprintf(os.Stderr,
-			"%s\n", err.Error())
-		os.Exit(1)
-	}
-}
-
-func parseSDB(raw []byte) error {
 	raw_len := len(raw)
 	if raw_len < 3 {
-		return fmt.Errorf("message structure too short: %d bytes",
+		return nil, fmt.Errorf("message structure too short: %d bytes",
 			len(raw))
 	}
 
@@ -110,20 +153,20 @@ func parseSDB(raw []byte) error {
 	sdb.Length = binary.BigEndian.Uint16(raw[1:3])
 
 	if (int(sdb.Length) + 3) != raw_len {
-		return fmt.Errorf("invalid message length (expected %d, got %d)",
+		return nil, fmt.Errorf("invalid message length (expected %d, got %d)",
 			(sdb.Length + 3), raw_len)
 	}
 
 	for i := 3; i < raw_len; {
 		if (i + 3) > raw_len {
-			return fmt.Errorf("invalid element length (at %d)",
+			return nil, fmt.Errorf("invalid element length (at %d)",
 				i)
 		}
 		el_iei := raw[i]
 		el_len := binary.BigEndian.Uint16(raw[i+1 : i+3])
 
 		if (i + 3 + int(el_len)) > raw_len {
-			return fmt.Errorf("invalid element length (at %d): %d",
+			return nil, fmt.Errorf("invalid element length (at %d): %d",
 				i+1, el_len)
 		}
 
@@ -134,7 +177,7 @@ func parseSDB(raw []byte) error {
 			moheader := MOHeader{}
 			err := binary.Read(buf, binary.BigEndian, &moheader)
 			if err != nil {
-				return fmt.Errorf("error reading MO header (at %d): %s",
+				return nil, fmt.Errorf("error reading MO header (at %d): %s",
 					i, err.Error())
 			}
 			sdb.Elements = append(sdb.Elements, moheader)
@@ -153,7 +196,7 @@ func parseSDB(raw []byte) error {
 			molocation := MOLocation{}
 			err := binary.Read(buf, binary.BigEndian, &molocation)
 			if err != nil {
-				return fmt.Errorf("error reading MO location (at %d): %s",
+				return nil, fmt.Errorf("error reading MO location (at %d): %s",
 					i, err.Error())
 			}
 			sdb.Elements = append(sdb.Elements, molocation)
@@ -167,55 +210,12 @@ func parseSDB(raw []byte) error {
 			sdb.Elements = append(sdb.Elements, moconfirmation)
 
 		default:
-			return fmt.Errorf("invalid element IEI (at %d): %d",
+			return nil, fmt.Errorf("invalid element IEI (at %d): %d",
 				i, el_iei)
 		}
 
 		i += (3 + int(el_len))
 	}
 
-	fmt.Printf("Protocol Revision: %d\n",
+	return &sdb, nil
-		sdb.ProtocolRevision)
-	fmt.Printf("Message Length: %d\n",
-		sdb.Length)
-	for c, i := range sdb.Elements {
-		if c > 0 {
-			fmt.Println()
-		}
-		switch v := i.(type) {
-		case MOHeader:
-			fmt.Printf("\tMO Header IEI: %d\n",
-				v.IEI)
-			fmt.Printf("\tMO Header Length: %d\n",
-				v.Length)
-			fmt.Printf("\tMO Header CDR Reference: %d\n",
-				v.CDRReference)
-			fmt.Printf("\tMO Header IMEI: %s\n",
-				v.IMEI)
-			fmt.Printf("\tMO Header Status: %s (%d)\n",
-				v.StatusString(), v.Status)
-			fmt.Printf("\tMO Header MOMSN: %d\n",
-				v.MOMSN)
-			fmt.Printf("\tMO Header MTMSN: %d\n",
-				v.MTMSN)
-			fmt.Printf("\tMO Header Session Time: %s\n",
-				v.SessionTime().String())
-
-		case MOPayload:
-			fmt.Printf("\tMO Payload IEI: %d\n",
-				v.IEI)
-			fmt.Printf("\tMO Payload Length: %d\n",
-				v.Length)
-
-		case MOConfirmation:
-			fmt.Printf("\tMO Confirmation IEI: %d\n",
-				v.IEI)
-			fmt.Printf("\tMO Confirmation Length: %d\n",
-				v.Length)
-			fmt.Printf("\tMO Confirmation Status: %d\n",
-				v.Status)
-		}
-	}
-
-	return nil
 }