//
// CONSTANTS FROM RFC 3927 www.ietf.org/rfc/rfc3927.txt
//
// The following 10 constant declarations are copied almost verbatim from Section 9
// "The following timing constants are used in this protocol; they are
// not intended to be user configurable."
const int PROBE_WAIT = 1; // second (initial random delay)
const int PROBE_NUM = 3; // (number of probe packets)
const int PROBE_MIN = 1; // second (minimum delay till repeated probe)
const int PROBE_MAX = 2; // seconds (maximum delay till repeated probe)
const int ANNOUNCE_WAIT = 2; // seconds (delay before announcing)
const int ANNOUNCE_NUM = 2; // (number of announcement packets)
const int ANNOUNCE_INTERVAL = 2; // seconds (time between announcement packets)
const int MAX_CONFLICTS = 10; // (max conflicts before rate limiting)
const int RATE_LIMIT_INTERVAL = 60; // second (delay between successive attempts)
const int DEFEND_INTERVAL = 10; // seconds (minimum interval between defensive ARPs).
//The following constants have been defined by us
const int k = 2; // number of hosts
const int m = 1; // number of available IP addresses
//Real value is 65024 but simulator can't handle that
const int n = 2; // number of network automata
typedef scalar[k] HAType;
typedef scalar[n] NetworkType;
int[0,m] IP[HAType]; // array recording (guessed) IP address for each host, 0 means no address guessed
bool UseIP[HAType]; // array recording whether host is using an IP address
// channels to send messages to network, receive messages from network, and to reset host
chan send_req,receive_msg[HAType],answer,no_answer,reset[HAType];
// trick to make certain transitions urgent
urgent broadcast chan urg;
typedef int[0,m] IPType;
typedef struct{
HAType senderHA; // sender hardware address
IPType senderIP; // sender IP address
IPType targetIP; // target IP address
bool request; // is the packet a Request or a Reply
}ARP_packet;
//auxiliary control variables needed for handling messages
bool response;
bool conflict;
//make following variable meta once this is implemented
ARP_packet packet;
Configconst HAType j//Insert local declarations of clocks, variables and constants.
clock x;
int [0,PROBE_NUM] counter; //number of probes or gratuitous ARP that have been sent
int [0,MAX_CONFLICTS] ConflictNum; //the number of times an address collision has occurred
PRE_CLAIMWAITCOLLISIONPROBEINITUSEInputHandlerconst HAType jclock y;
void ihandler(bool defend)
{
if (IP[j]==0) // Scenario A: I have not selected an IP address
{response:=false; conflict:=false;}
else if (packet.senderHA==j) // Scenario B: I have sent the packet myself
{response:=false; conflict:=false;}
else if (packet.senderIP==IP[j]) //There is a conflict: somebody else is using my IP address!
{
conflict:=true;
if (not UseIP[j]) // Scenario C: select a new address
response:=false;
else if (defend) // Scenario D: I am going to defend my address
response:=true;
else // Scenario E: I will not defend my address
response:=false;
}
else if (not UseIP[j])
{
response:=false;
if (packet.targetIP==IP[j] && packet.request && packet.senderIP==0) // Scenario F: conflicting probe
conflict:=true;
else //Scenario G: Packet is not conflicting with IP address that I want to use
conflict:=false;
}
else // Incoming packet is not conflicting with IP address that I am using
{
conflict:=false;
if (packet.targetIP==IP[j] && packet.request) // Scenario H: answer regular ARP request
response:=true;
else // Scenario I: no reply message required
response:=false;
}
}
Networkconst NetworkType jclock z;
bool sent[HAType],replied[HAType];
ARP_packet answer_buffer, send_buffer;
void init_vars(){
for(i: HAType){
sent[i]:=false;
replied[i]:=false;
};
answer_buffer.senderIP:=0;
answer_buffer.targetIP:=0;
answer_buffer.request:=false;
}
bool all_sent(){
// the request packet has been sent to all
// and if there is an answer it has been sent to all
return ((forall (i : HAType) sent[i]) and ((answer_buffer.senderIP!=0) imply (forall (i : HAType) replied[i])));
}DELIVERIDLERegularconst HAType j
system
Config, InputHandler,Regular,Network;