osmo-st-gsm/SCCPHandler.st

"
 (C) 2010 by Holger Hans Peter Freyther
 All Rights Reserved

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as
 published by the Free Software Foundation, either version 3 of the
 License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU Affero General Public License for more details.

 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
"

PackageLoader fileInPackage: 'OsmoNetwork'.

Object subclass: SCCPConnection [
    | src dst queue conManager confirmSem proc state |

    SCCPConnection class >> stateInitial   [ ^ 0 ]
    SCCPConnection class >> stateConnected [ ^ 1 ]
    SCCPConnection class >> stateReleased  [ ^ 2 ]
    SCCPConnection class >> stateTimeout   [ ^ 3 ]

    SCCPConnection class >> new [
        ^ super new
            initialize; yourself
    ]

    initialize [
        state := SCCPConnection stateInitial.
        confirmSem := Semaphore new.
        queue := SharedQueue new.
    ]

    conManager: aHandler [
        <category: 'private'>
        conManager := aHandler.
    ]

    readQueue [
        <category: 'private'>
        ^ queue
    ]

    srcRef [
        <category: 'access'>
        ^ src
    ]
    srcRef: aRef [
        <category: 'access'>
        src := aRef
    ]

    dstRef: aRef [
        <category: 'access'>
        dst := aRef
    ]

    dstRef [
        <category: 'access'>
        ^ dst
    ]

    next [
        "Read the next item. If the connection is terminated"
        | msg |

        "If we are not connected we need to wait"
        state = SCCPConnection stateInitial
            ifTrue: [
                self waitForConfirmation.
        ].

        "If we are not connected here. Send a EndOfStream signal"
        (state > SCCPConnection stateConnected and: [self readQueue isEmpty])
            ifTrue: [
                ^ SystemExceptions.EndOfStream signal
        ].

        msg := self readQueue next.

        "If this is a small integer our connection is gone"
        (msg isKindOf: SmallInteger)
            ifTrue: [
                ^ SystemExceptions.EndOfStream signal
        ].

        "We do have a real message"
        ^ msg
    ]

    nextPutData: aMsg [
        | dt1 |
        dt1 := Osmo.SCCPConnectionData initWith: self dstRef data: aMsg.
        self nextPut: dt1 toMessage.
    ]

    nextPut: aMsg [
        conManager sendMsg: aMsg.
    ]

    waitForConfirmation [
        "Wait for the connection to be confirmed and then exit"

        ((Delay forSeconds: 10) timedWaitOn: confirmSem)
            ifTrue: [
                state := SCCPConnection stateTimeout.
                conManager connectionTimeout: self.
                ^ false
            ].

        ^ true
    ]


    "SCCP Connection state handling"
    terminate [
        self readQueue nextPut: 0.
    ]

    confirm: aCC [
        <category: 'connection-handling'>
        self dstRef: aCC src.
        state := SCCPConnection stateConnected.
        confirmSem signal.
    ]

    data: aDT [
        self readQueue nextPut: aDT data.
    ]

    released: aRLSD [
        | rlc |
        "Give up local resources here. We are done."

        state := SCCPConnection stateReleased.
        rlc := Osmo.SCCPConnectionReleaseComplete
                    initWithDst: aRLSD src src: aRLSD dst.
        self nextPut: rlc toMessage.
        self terminate.
    ]
]

Object subclass: MSGParser [
    <comment: 'I take a SCCP message and recursively parse all the data'>

    MSGParser class >> parse: aByteArray [
        | sccp |
        "Return a completely decoded subtree"

        sccp := Osmo.SCCPMessage decode: aByteArray.
        (sccp respondsTo: #data)
            ifTrue: [
                sccp data: (self decodeBSSAP: sccp data).
        ].

        ^ sccp
    ]

    MSGParser class >> decodeBSSAP: aData [
        | bssap |
        bssap := BSSAPMessage decode: aData.
        bssap class msgType = BSSAPDTAP msgType
            ifTrue: [
                bssap data: (GSM48MSG decode: bssap data)
            ]
            ifFalse: [
                bssap data: (self decodeBSSMAP: bssap data).
            ].

        ^ bssap
    ]

    MSGParser class >> decodeBSSMAP: aData [
        | bssmap |
        bssmap := IEMessage decode: aData with: GSM0808IE.
        bssmap findIE: (GSMLayer3Info elementId) ifPresent: [:each |
            each data: (GSM48MSG decode: each data).
        ].
        ^ bssmap
    ]

]

Object subclass: SCCPHandler [
    | connections last_ref connection |
    <comment: 'I handle SCCP messages'>

    registerOn: aDispatcher [
        aDispatcher addHandler: Osmo.IPAConstants protocolSCCP
                    on: self with: #handleMsg:.
    ]

    connectionTimeout: aConnection [
        ('SCCP Connection ', aConnection srcRef asString, ' timeout.') printNl.
        self connections remove: aConnection.
    ]

    forwardMessage: aMessage with: aConnection[
        (aMessage isKindOf: Osmo.SCCPConnectionConfirm)
            ifTrue: [
                aConnection confirm: aMessage.
                ^ true
        ].
        (aMessage isKindOf: Osmo.SCCPConnectionData)
            ifTrue: [
                aConnection data: aMessage.
                ^ true
        ].
        (aMessage isKindOf: Osmo.SCCPConnectionReleased)
            ifTrue: [
                aConnection released: aMessage.
                self connections remove: aConnection.
                ^ true
        ].

        "Message is not handled here"
        ^ false
    ]

    dispatchMessage: aMessage [
        self connections do: [:each |
            each srcRef = aMessage dst
                ifTrue: [
                    ^ self forwardMessage: aMessage with: each.
            ].
        ].

        'No one has handled the connection with ', aMessage dst asString printNl.
    ]

    handleMsg: aMsg [
        | sccp |

        [
            sccp := MSGParser parse: (aMsg asByteArray).
        ] on: Exception do: [
            self logError: 'Failed to parse message' area: #sccp.
            aMsg toMessageOrByteArray printNl.
            ^ false
        ].

        self dispatchMessage: sccp.
    ]


    connection: aConnection [
        connection := aConnection.
    ]

    sendMsg: aMsg [
        "Send a SCCP message."
        connection send: aMsg with: Osmo.IPAConstants protocolSCCP.
    ]

    createConnection: aData [
        | con res|

        con := SCCPConnection new.
        con srcRef: self assignSrcRef.
        con conManager: self.
        res := Osmo.SCCPConnectionRequest
                initWith: (con srcRef) dest: (Osmo.SCCPAddress createWith: 254) data: aData.
        self connections add: con.
        self sendMsg: res toMessage.

        ^ con
    ]

    referenceIsFree: aRef [
        <category: 'private'>
        self connections do: [:each |
            each srcRef = aRef
                ifTrue: [
                    ^ false
            ].
        ].

        ^ true
    ]

    assignSrcRef [
        "Find a free SCCP reference"
        1 to: 16rFFFFFE do: [:dummy |
            | ref |
            ref := Random between: 1 and: 16rFFFFFE.
            (self referenceIsFree: ref)
                ifTrue: [
                    ^ ref.
            ].
        ].

        self error: 'No free SCCP Connection. Close some'.
    ]

    connections [
        ^ connections ifNil: [ connections := OrderedCollection new. ]
    ]
]