PCARP.C
上传用户:sunrenlu
上传日期:2022-06-13
资源大小:1419k
文件大小:9k
- /*
- * Address Resolution Protocol
- *
- * Externals:
- * _arp_handler( pb ) - returns 1 on handled correctly, 0 on problems
- * _arp_resolve - rets 1 on success, 0 on fail
- * - does not return hardware address if passed NULL for buffer
- *
- */
- #include <copyright.h>
- #include <wattcp.h>
- #include <string.h>
- #include <mem.h>
- #define MAX_ARP_DATA 40
- #define MAX_ARP_ALIVE 300 /* five minutes */
- #define MAX_ARP_GRACE 100 /* additional grace upon expiration */
- extern word wathndlcbrk;
- extern word watcbroke;
- extern word multihomes;
- typedef struct {
- longword ip;
- eth_address hardware;
- byte flags;
- byte bits; /* bits in network */
- longword expiry;
- } arp_tables;
- typedef struct {
- longword gate_ip;
- longword subnet;
- longword mask;
- } gate_tables;
- #define ARP_FLAG_NEED 0
- #define ARP_FLAG_FOUND 1
- #define ARP_FLAG_FIXED 255 /* cannot be removed */
- /*
- * arp resolution cache - we zero fill it to save an initialization routine
- */
- static arp_tables arp_data[ MAX_ARP_DATA ] =
- { {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL},
- {0uL,{{0,0,0,0,0,0}},0,0,0uL}, {0uL,{{0,0,0,0,0,0}},0,0,0uL}};
- gate_tables _arp_gate_data[ MAX_GATE_DATA ];
- word _arp_last_gateway;
- extern void (*system_yield)(); /* from pctcp.c 2000.4.14 EE */
- /*
- * _arp_add_gateway - if data is NULL, don't use string
- */
- void _arp_add_gateway( char *data, longword ip )
- {
- int i;
- char *subnetp, *maskp;
- longword subnet, mask;
- subnet = mask = 0;
- if ( data ) {
- maskp = NULL;
- if ( (subnetp = strchr( data, ',' )) != NULL ) {
- *subnetp++ = 0;
- if ( (maskp = strchr( subnetp, ',' )) != NULL ) {
- *maskp++ = 0;
- mask = aton( maskp );
- subnet = aton( subnetp );
- } else {
- subnet = aton( subnetp );
- switch ( subnet >> 30 ) {
- case 0 :
- case 1 : mask = 0xff000000L; break;
- case 2 : mask = 0xfffffe00L; break; /* minimal class b */
- case 3 : mask = 0xffffff00L; break;
- }
- }
- }
- ip = aton( data );
- }
- if ( _arp_last_gateway < MAX_GATE_DATA ) {
- for ( i = 0 ; i < _arp_last_gateway ; ++i ) {
- if ( _arp_gate_data[i].mask < mask ) {
- movmem( &_arp_gate_data[i], &_arp_gate_data[i+1],
- (_arp_last_gateway - i) * sizeof( gate_tables ));
- break;
- }
- }
- _arp_gate_data[i].gate_ip = ip;
- _arp_gate_data[i].subnet = subnet;
- _arp_gate_data[i].mask = mask;
- ++_arp_last_gateway; /* used up another one */
- }
- }
- static void _arp_request( longword ip )
- {
- arp_Header *op;
- op = (arp_Header *)_eth_formatpacket(&_eth_brdcast, 0x608);
- op->hwType = arp_TypeEther;
- op->protType = 0x008; /* IP */
- op->hwProtAddrLen = sizeof(eth_address) + (sizeof(longword)<<8);
- op->opcode = ARP_REQUEST;
- op->srcIPAddr = intel( my_ip_addr );
- movmem(&_eth_addr, &op->srcEthAddr, sizeof(eth_address));
- op->dstIPAddr = intel( ip );
- /* ...and send the packet */
- _eth_send( sizeof(arp_Header) );
- }
- static word arp_index = 0; /* rotates round-robin */
- static arp_tables *_arp_search( longword ip, int create )
- {
- int i;
- arp_tables *arp_ptr;
- for ( i = 0; i < MAX_ARP_DATA; ++i ) {
- if ( ip == arp_data[i].ip )
- return( &arp_data[i] );
- }
- /* didn't find any */
- if ( create ) {
- /* pick an old or empty one */
- for ( i = 0; i < MAX_ARP_DATA ; ++i ) {
- arp_ptr = &arp_data[i];
- if ( ! arp_ptr->ip || chk_timeout(arp_ptr->expiry+MAX_ARP_GRACE))
- return( arp_ptr );
- }
- /* pick one at pseudo-random */
- return( &arp_data[ arp_index = ( arp_index + 1 ) % MAX_ARP_DATA ] );
- }
- return( NULL );
- }
- void _arp_register( longword use, longword instead_of )
- {
- /* word i; */
- arp_tables *arp_ptr;
- if ( (arp_ptr = _arp_search( instead_of, 0 )) != NULL) {
- /* now insert the address of the new guy */
- arp_ptr->flags = ARP_FLAG_NEED;
- _arp_resolve( use, &arp_ptr->hardware, 0);
- arp_ptr->expiry = set_timeout( MAX_ARP_ALIVE );
- return;
- }
- arp_ptr = _arp_search( use , 1 ); /* create a new one */
- arp_ptr->flags = ARP_FLAG_NEED;
- /* but now is this right? if 'use' was already in the arp cache,
- we're now nuking it... at worst an efficiency problem */
- arp_ptr->ip = instead_of; /* use; */ /* 94.11.30 */
- _arp_resolve( use, &arp_ptr->hardware, 0);
- arp_ptr->expiry = set_timeout( MAX_ARP_ALIVE );
- }
- void _arp_tick( longword ip )
- {
- arp_tables *arp_ptr;
- if ( (arp_ptr = _arp_search( ip , 0)) != NULL )
- arp_ptr->expiry = set_timeout( MAX_ARP_ALIVE );
- }
- /*
- * _arp_handler - handle incomming ARP packets
- */
- int _arp_handler( arp_Header *in)
- {
- arp_Header *op;
- longword his_ip;
- arp_tables *arp_ptr;
- if ( in->hwType != arp_TypeEther || /* have ethernet hardware, */
- in->protType != 8 ) /* and internet software, */
- return( 0 );
- /* continuously accept data - but only for people we talk to */
- his_ip = intel( in->srcIPAddr );
- if ( (arp_ptr = _arp_search( his_ip, 0)) != NULL ) {
- arp_ptr->expiry = set_timeout( MAX_ARP_ALIVE );
- movmem( &in->srcEthAddr, &arp_ptr->hardware, sizeof( eth_address ));
- arp_ptr->flags = ARP_FLAG_FOUND;
- }
- /* does someone else want our Ethernet address ? */
- if ( in->opcode == ARP_REQUEST && /* and be a resolution req. */
- ((longword)(intel(in->dstIPAddr) - my_ip_addr ) <= multihomes )
- ) {
- op = (arp_Header *)_eth_formatpacket(&in->srcEthAddr, 0x0608);
- op->hwType = arp_TypeEther;
- op->protType = 0x008; /* intel for ip */
- op->hwProtAddrLen = sizeof(eth_address) + (sizeof(longword) << 8 );
- op->opcode = ARP_REPLY;
- op->dstIPAddr = in->srcIPAddr;
- op->srcIPAddr = in->dstIPAddr;
- movmem(&_eth_addr, &op->srcEthAddr, sizeof(eth_address));
- movmem(&in->srcEthAddr, &op->dstEthAddr, sizeof(eth_address));
- _eth_send(sizeof(arp_Header));
- return ( 1 );
- }
- return( 1 );
- }
- /*
- * _arp_resolve - resolve IP address to hardware address
- */
- int _arp_resolve( longword ina, eth_address *ethap, int nowait )
- {
- static arp_tables *arp_ptr;
- int i, oldhndlcbrk;
- longword timeout, resend;
- /* int packettype; */
- if ( _pktdevclass == PD_SLIP ) {
- /* we are running slip or somthing which does not use addresses */
- return( 1 );
- }
- if ( (longword)(ina - my_ip_addr) < multihomes) {
- if (ethap)
- movmem( &_eth_addr, ethap, sizeof( eth_address ));
- return( 1 );
- }
- /* attempt to solve with ARP cache */
- /* fake while loop */
- while ( (arp_ptr = _arp_search( ina, 0)) != NULL ) {
- if ( arp_ptr->flags != ARP_FLAG_NEED ) {
- /* has been resolved */
- #ifdef NEW_EXPIRY
- if ( chk_timeout( arp_ptr->timeout ) {
- if ( ! chk_timeout( arp_ptr->timeout + MAX_ARP_GRACE ) {
- /* we wish to refresh it asynchronously */
- _arp_request( ina );
- else
- break; /* must do full fledged arp */
- #endif NEW_EXPIRY
- if (ethap)
- movmem( &arp_ptr->hardware, ethap, sizeof(eth_address));
- return( 1 );
- }
- break;
- }
- /* make a new one if necessary */
- if (! arp_ptr )
- arp_ptr = _arp_search( ina, 1 );
- /* we must look elsewhere - but is it on our subnet??? */
- if (( ina ^ my_ip_addr ) & sin_mask ) {
- /* not of this network */
- for ( i = 0; i < _arp_last_gateway ; ++i ) {
- // is the gateway on our subnet
- // or if mask is ff...ff, we assume any gateway must succeed
- // because we are on 'no' network
- if ((((_arp_gate_data[i].gate_ip ^ my_ip_addr ) & sin_mask ) == 0)
- || ( sin_mask == 0xffffffffL )) {
- /* compare the various subnet bits */
- if ( (_arp_gate_data[i].mask & ina ) == _arp_gate_data[i].subnet ) {
- if ( _arp_resolve( _arp_gate_data[i].gate_ip , ethap, nowait ))
- return( 1 );
- }
- }
- }
- return( 0 );
- }
- /* return if no host, or no gateway */
- if (! ina )
- return( 0 );
- /* is on our subnet, we must resolve */
- timeout = set_timeout( 5 ); /* five seconds is long for ARP */
- oldhndlcbrk = wathndlcbrk;
- wathndlcbrk = 1;
- watcbroke = 0;
- while ( !chk_timeout( timeout )) {
- /* do the request */
- _arp_request( arp_ptr->ip = ina );
- resend = set_timeout( 1 ) - 14L; /* 250 ms */
- while (!chk_timeout( resend )) {
- if (watcbroke) goto fail;
- tcp_tick( NULL );
- if ( arp_ptr->flags) {
- if (ethap)
- movmem( &arp_ptr->hardware, ethap, sizeof(eth_address));
- arp_ptr->expiry = set_timeout( MAX_ARP_ALIVE );
- watcbroke = 0;
- wathndlcbrk = oldhndlcbrk;
- return ( 1 );
- }
- /* EE 2000.4.14 */
- if ( system_yield != NULL )
- (*system_yield)();
- }
- if ( nowait ) goto fail;
- }
- fail:
- watcbroke = 0;
- wathndlcbrk = oldhndlcbrk;
- return ( 0 );
- }