//
// 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 specify the dimensions of the model
const int l = 2; // number of hardware addresses (including all zeroes address)
const int m = 2; // number of available link local IP addresses
//real value is 65024 but simulator can't handle that
const int n = 3; // number of network automata
typedef scalar[l] HAtype;
typedef scalar[m+1] IPtype; //an IP address in our model is either a link local address or the zero address
IPtype zero;
typedef scalar[n] Networktype;
IPtype IP[HAtype]; // array recording (guessed) IP address for each host, zero means no address guessed
bool UseIP[HAtype]; // array recording whether host is using an IP address
// channels to send messages to network, reset a host, receive messages from network, and to send answers back to network
chan send_req,reset[HAtype],receive_msg[Networktype][HAtype],send_answer[Networktype];
// trick to make certain transitions urgent
urgent broadcast chan urg;
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;
meta HAtype ha0;
void initialize(ARP_packet& p)
{
p.senderHA := ha0;
p.senderIP := zero;
p.targetIP := zero;
p.request := false;
}
//meta because it is used only for value passing in synchronizations
meta ARP_packet packet;
Configconst HAtype hclock 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 occurredPRE_CLAIMWAITCOLLISIONPROBEINITCLAIMEDRegularconst HAtype hINITInputHandlerconst HAtype hclock y;
ARP_packet answer;
Networktype network;
bool do_reset;
void ihandler(bool defend)
{
if (IP[h]==zero) // Scenario A: I have not selected an IP address
;
else if (packet.senderHA==h) // Scenario B: I have sent the packet myself
;
else if (packet.senderIP==IP[h]) //There is a conflict: somebody else is using my address!
{
if (not UseIP[h]) // Scenario C: select a new address
do_reset:=true;
else if (defend) // Scenario D: I am going to defend my address
{
answer.senderHA:=h;
answer.senderIP:=IP[h];
answer.targetIP:=IP[h];
answer.request:=true;
y:=0;
}
else // Scenario E: I will not defend my address
do_reset:=true;
}
else if (not UseIP[h])
{
if (packet.targetIP==IP[h] && packet.request && packet.senderIP==zero) // Scenario F: conflicting probe
do_reset:=true;
else //Scenario G: Packet is not conflicting with IP address that I want to use
;
}
else // Packet is not conflicting with IP address that I am using
{
if (packet.targetIP==IP[h] && packet.request) // Scenario H: answer regular ARP request
{
answer.senderHA:=h;
answer.senderIP:=IP[h];
answer.targetIP:=packet.senderIP;
answer.request:=false;
}
else // Scenario I: no reply message required
;
}
}
BUSYINITIDLENetworkconst Networktype wclock z;
bool send[HAtype];
bool answer[HAtype];
ARP_packet s_buffer;
ARP_packet a_buffer;
void set(bool& a[HAtype]) {
for(i:HAtype){a[i]:=true;}
}
BUSYIDLEsystem Config, InputHandler,Regular,Network;