From c28b116689b03dcbd426e8028914bd3b6fa7b878 Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <zecke@selfish.org>
Date: Mon, 22 Nov 2010 17:11:08 +0100
Subject: [PATCH] Decode: Work on decoding the messages...

This is a lot of work in progress to recursively decode
the messages.
---
 BSSAP.st    | 41 +++++++++++++++++++++++++-----
 Messages.st | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 Tests.st    | 18 +++++++++++++
 3 files changed, 126 insertions(+), 6 deletions(-)

diff --git a/BSSAP.st b/BSSAP.st
index 58569d0..b5128ae 100644
--- a/BSSAP.st
+++ b/BSSAP.st
@@ -28,24 +28,53 @@ Object subclass: BSSAPHelper [
     ]
 ]
 
-Object subclass: BSSAPManagement [
-    | payload |
+Object subclass: BSSAPMessage [
+    BSSAPMessage class >> decode: bssap [
+        | type |
+        type := bssap at: 1.
 
+        BSSAPMessage allSubclassesDo: [:each |
+            each msgType = type
+                ifTrue: [
+                    ^ each parseFrom: bssap.
+            ]
+        ].
+
+        ^ Error signal: 'No handler for: ', type asString.
+    ]
+]
+
+BSSAPMessage subclass: BSSAPManagement [
+    | data |
+
+    BSSAPManagement class >> msgType [ <category: 'factory'> ^ BSSAPHelper msgManagemnt ]
     BSSAPManagement class >> initWith: data [
         ^ (self new)
-            payload: data;
+            data: data;
             yourself.
     ]
 
-    payload: aPayload [
-        payload := aPayload.
+    BSSAPMessage class >> parseFrom: aByteArray [
+        | size data |
+        size := aByteArray at: 2.
+        data := aByteArray copyFrom: 3 to: 2 + size.
+
+        ^ BSSAPManagement initWith: data.
+    ]
+
+    data: aPayload [
+        data := aPayload.
+    ]
+
+    data [
+        ^ data
     ]
 
     writeOn: aMsg [
         | dat |
         aMsg putByte: BSSAPHelper msgManagemnt.
 
-        dat := payload toMessageOrByteArray.
+        dat := data toMessageOrByteArray.
         aMsg putByte: dat size.
         aMsg putByteArray: dat.
     ]
diff --git a/Messages.st b/Messages.st
index 6976296..bc8c908 100644
--- a/Messages.st
+++ b/Messages.st
@@ -1,4 +1,38 @@
 "General IE based message handling"
+Object subclass: DataIE [
+    | type data |
+
+    <category: 'osmo-messages'>
+    DataIE class >> initWith: aType data: aData [
+        ^ self new
+            type: aType;
+            data: aData;
+            yourself
+    ]
+
+    type [
+        ^ type
+    ]
+
+    type: aType [
+        type := aType.
+    ]
+
+    data [
+        ^ data
+    ]
+
+    data: aData [
+        data := aData.
+    ]
+
+    writeOn: aMsg [
+        aMsg putByte: type.
+        aMsg putByte: data size.
+        aMsg putByteArray: data.
+    ]
+]
+
 Object subclass: IEMessage [
     <category: 'osmo-messages'>
     | ies type |
@@ -10,11 +44,50 @@ Object subclass: IEMessage [
             yourself
     ]
 
+    IEMessage class >> findIE: type with: data from: IEBase [
+        "TODO: This needs to move some basic dispatch class"
+        "Find the IE that handles the type specified"
+
+        ^ DataIE initWith: type data: data.
+"
+        IEBase allSubclassesDo: [:each |
+            each elementId = type
+                    ifTrue: [
+                       ^ each parseFrom: data.
+                ].
+            ].
+
+        ^ Exception signal: 'Unsupported IE type: ', type.
+"
+    ]
+
+    IEMessage class >> decode: aByteArray with: IEBase [
+        | msg dat |
+        msg := IEMessage initWith: (aByteArray at: 1).
+
+        dat := aByteArray copyFrom: 2.
+        [dat isEmpty not] whileTrue: [
+            | type size data |
+            type := dat at: 1.
+            size := dat at: 2.
+            data := dat copyFrom: 3 to: 2 + size.
+            dat  := dat copyFrom: 3 + size.
+
+            msg addIe: (self findIE: type with: data from: IEBase).
+        ].
+
+        ^ msg
+    ]
+
     type: aType [
         <category: 'creation'>
         type := aType.
     ]
 
+    type [
+        ^ type
+    ]
+
     addIe: aIe [
         <category: 'creation'>
         self ies add: aIe.
diff --git a/Tests.st b/Tests.st
index b25afb8..19fbca7 100644
--- a/Tests.st
+++ b/Tests.st
@@ -44,6 +44,16 @@ TestCase subclass: GSM0808Test [
                  16r75 16r30 16r17 16r03 16r01 16r02 16r03) asByteArray.
         self assert: buf asByteArray = res
     ]
+
+    testIEDecoding [
+        | inp res |
+        inp := #(16r57 16r05 16r08 16r00 16r72 16rF4 16r80 16r20 16r12
+                 16r75 16r30 16r17 16r03 16r01 16r02 16r03) asByteArray.
+
+        res := IEMessage decode: inp with: GSM0808IE.
+        self assert: res type = GSM0808Helper msgComplL3.
+        self assert: res ies size = 2.
+    ]
 ]
 
 TestCase subclass: BSSAPTest [
@@ -63,6 +73,14 @@ TestCase subclass: BSSAPTest [
         self assert: man toMessage asByteArray = #(0 3 1 2 3) asByteArray.
     ]
 
+    testParseManagement [
+        | man |
+
+        man := BSSAPMessage decode: #(0 3 1 2 3) asByteArray.
+        self assert: (man isKindOf: BSSAPManagement).
+        self assert: man data = #(1 2 3) asByteArray.
+    ]
+
     testPrependDTAP [
         | msg |
         msg := Osmo.MessageBuffer new.