checking session type when handling submit_sm and sending MO message

README.md

@@ -4,39 +4,52 @@
 
 Lightweight, zero-dependency and stupid SMSc simulator.
 
-### Warning
-
-* simulator implements only a small subset of the SMPP3.4 specification and supports only the following PDUs:
- - `bind_transmitter`, `bind_receiver`, `bind_transceiver`
- - `unbind`
- - `submit_sm`
- - `enquire_link`
- - `deliver_sm_resp`
-* simulator does not perform PDU validation
-
 ### Usage
 
-```bash
-> go build
-> ./smscsim
+1) Build from sources (need golang compiler)
+
 ```
+go build
+./smscsim
+```
+
+2) Build docker image
 
-This will start smpp server on port _2775_ and web server on port _12775_.
+```
+docker build -t smscsim .
+docker run -p 2775:2775 -p 12775:12775 smscsim
+```
 
-or
+3) Use prebuild docker image (from hub.docker.com)
 
-```bash
-> docker run -p 2775:2775 -p 12775:12775 ukarim/smscsim
 ```
+docker run -p 2775:2775 -p 12775:12775 ukarim/smscsim
+```
+
+then, just configure your smpp client to connect to `localhost:2775`
+
+### Features
 
-### Delivery reports
+#### Delivery reports (DLR)
 
-If it was requested by _submit_sm_ packet, delivery receipt will be returned after 2 sec with a message state always set to _DELIVERED_.
+If it was requested by _submit_sm_ packet, delivery receipt will be returned
+after 2 sec with a message state always set to _DELIVERED_.
 
-### MO messages
+#### MO messages
+
+Mobile originated messages (from `smsc` to `smpp client`) can be sent using
+special web page available at `http://localhost:12775` . MO message will be
+delivered to the selected smpp session using a _deliver_sm_ PDU.
+
+### Warning
 
-MO messages can be triggered using a special web page http://localhost:12775.
-MO message will be delivered to the selected smpp session using a _deliver_sm_ PDU.
+* simulator implements only a small subset of the SMPP3.4 specification and supports only the following PDUs:
+ - `bind_transmitter`, `bind_receiver`, `bind_transceiver`
+ - `unbind`
+ - `submit_sm`
+ - `enquire_link`
+ - `deliver_sm_resp`
+* simulator does not perform PDU validation
 
 ### Env variables
 

smsc.go

@@ -34,6 +34,7 @@ const (
 const (
  STS_OK = 0x00000000
  STS_INVALID_CMD = 0x00000003
+ STS_INV_BIND_STS = 0x00000004
  STS_ALREADY_BOUND = 0x00000005
 )
 
@@ -43,8 +44,9 @@ const (
 )
 
 type Session struct {
- SystemId string
- Conn net.Conn
+ SystemId string
+ Conn net.Conn
+ ReceiveMo bool
 }
 
 type Tlv struct {
@@ -93,9 +95,11 @@ func (smsc *Smsc) BoundSystemIds() []string {
 
 func (smsc *Smsc) SendMoMessage(sender, recipient, message, systemId string) error {
  var conn net.Conn
+ receiveMo := false
  for _, sess := range smsc.Sessions {
  if systemId == sess.SystemId {
  conn = sess.Conn
+ receiveMo = sess.ReceiveMo
  }
  }
 
@@ -104,6 +108,11 @@ func (smsc *Smsc) SendMoMessage(sender, recipient, message, systemId string) err
  return fmt.Errorf("No session found for systemId: [%s]", systemId)
  }
 
+ if !receiveMo {
+ log.Printf("Cannot send MO message to systemId: [%s]. Only RECEIVER and TRANSCEIVER sessions could receive MO messages", systemId)
+ return fmt.Errorf("Only RECEIVER and TRANSCEIVER sessions could receive MO messages")
+ }
+
  // TODO implement UDH for large messages
  shortMsg := truncateString(message, 70) // just truncate to 70 symbols
  var tlvs []Tlv
@@ -123,6 +132,7 @@ func handleSmppConnection(smsc *Smsc, conn net.Conn) {
  sessionId := rand.Int()
  systemId := "anonymous"
  bound := false
+ receiver := false
 
  defer delete(smsc.Sessions, sessionId)
  defer conn.Close()
@@ -165,9 +175,11 @@ func handleSmppConnection(smsc *Smsc, conn net.Conn) {
  respBytes = headerPDU(respCmdId, STS_ALREADY_BOUND, seqNum)
  log.Printf("[%s] already has bound session", systemId)
  } else {
- smsc.Sessions[sessionId] = Session{systemId, conn}
+ receiveMo := cmdId == BIND_RECEIVER || cmdId == BIND_TRANSCEIVER
+ smsc.Sessions[sessionId] = Session{systemId, conn, receiveMo}
  respBytes = stringBodyPDU(respCmdId, STS_OK, seqNum, "smscsim")
  bound = true
+ receiver = cmdId == BIND_RECEIVER
  }
  }
  case UNBIND: // unbind request
@@ -236,20 +248,25 @@ func handleSmppConnection(smsc *Smsc, conn net.Conn) {
 
  // prepare submit_sm_resp
  msgId := strconv.Itoa(rand.Int())
- respBytes = stringBodyPDU(SUBMIT_SM_RESP, STS_OK, seqNum, msgId)
-
- if registeredDlr != 0 {
- go func() {
- time.Sleep(2000 * time.Millisecond)
- now := time.Now()
- dlr := deliveryReceiptPDU(msgId, now, now)
- if _, err := conn.Write(dlr); err != nil {
- log.Printf("error sending delivery receipt to system_id[%s] due %v.", systemId, err)
- return
- } else {
- log.Printf("delivery receipt for message [%s] was send to system_id[%s]", msgId, systemId)
- }
- }()
+
+ if receiver {
+ respBytes = headerPDU(SUBMIT_SM_RESP, STS_INV_BIND_STS, seqNum)
+ } else {
+ respBytes = stringBodyPDU(SUBMIT_SM_RESP, STS_OK, seqNum, msgId)
+
+ if registeredDlr != 0 {
+ go func() {
+ time.Sleep(2000 * time.Millisecond)
+ now := time.Now()
+ dlr := deliveryReceiptPDU(msgId, now, now)
+ if _, err := conn.Write(dlr); err != nil {
+ log.Printf("error sending delivery receipt to system_id[%s] due %v.", systemId, err)
+ return
+ } else {
+ log.Printf("delivery receipt for message [%s] was send to system_id[%s]", msgId, systemId)
+ }
+ }()
+ }
  }
  }
  case DELIVER_SM_RESP: // deliver_sm_resp