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Annotation of xinu/sys/getpath.c, revision 1.1.1.1

1.1       root        1: /* getpath.c - getpath */
                      2: 
                      3: #include <conf.h>
                      4: #include <kernel.h>
                      5: #include <proc.h>
                      6: #include <network.h>
                      7: 
                      8: /*------------------------------------------------------------------------
                      9:  *  getpath  -  find a path (route table entry) for a given IP address
                     10:  *------------------------------------------------------------------------
                     11:  */
                     12: getpath(faddr)
                     13: IPaddr faddr;
                     14: {
                     15:        int     i;
                     16:        int     arindex;                /* route table entry index      */
                     17:        int     mypid;                  /* local copy of my process id  */
                     18:        IPaddr  myaddr;                 /* my IP address                */
                     19:        PStype  ps;
                     20:        register struct arpent  *arpptr;
                     21:        register struct arppak  *apacptr;
                     22:        struct  epacket *packet, *mkarp();
                     23: 
                     24:        wait(Arp.arpsem);
                     25:        arpptr = &Arp.arptab[ arindex = arpfind(faddr) ];
                     26:        if (arpptr->arp_state != AR_ALLOC) {
                     27:                signal(Arp.arpsem);
                     28:                return(arindex);
                     29:        }
                     30: 
                     31:        /* Use ARP to obtain and record IP-to-Ether binding */
                     32:        
                     33:        getaddr(myaddr);
                     34:        mypid = getpid();
                     35:        for (i=0 ; i < AR_RTRY ; i++) {
                     36:                packet = mkarp(EP_ARP, AR_REQ, myaddr, faddr);
                     37:                blkcopy(Arp.arpwant, faddr, AR_PLEN);
                     38:                disable(ps);
                     39:                Arp.arppid = mypid;
                     40:                recvclr();
                     41:                write(ETHER, packet, EMINPAK);
                     42:                restore(ps);
                     43:                if (recvtim(AR_TIME) == OK)
                     44:                        break;
                     45:        }
                     46:        Arp.arppid = BADPID;
                     47:        signal(Arp.arpsem);
                     48:        return(arindex);
                     49: }

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