IP协议c源代码（注意，只是单独的IP协议包哦）

/* ipproc.c - ipproc */ #include <conf.h> #include <kernel.h> #include <network.h> #include <bufpool.h> #include <dos.h> struct ep *ipgetp(); struct route *rtget(); /*------------------------------------------------------------------------ * ipproc - handle an IP datagram coming in from the network *------------------------------------------------------------------------ */ PROCESS ipproc() { struct ep *pep; struct ip *pip; struct route *prt; Bool nonlocal; int ifnum, rdtype; ippid = getpid(); /* so others can find us */ signal(Net.sema); /* signal initialization done */ while (TRUE) { pep = ipgetp(&ifnum); pip = (struct ip *)pep->ep_data; if ((pip->ip_verlen>>4) != IP_VERSION) { IpInHdrErrors++; freebuf(pep); continue; } if (IP_CLASSD(pip->ip_dst) || IP_CLASSE(pip->ip_dst)) { IpInAddrErrors++; freebuf(pep); continue; } if (ifnum != NI_LOCAL) { if (cksum(pip, IP_HLEN(pip)>>1)) { IpInHdrErrors++; freebuf(pep); continue; } ipnet2h(pip); } prt = rtget(pip->ip_dst, (ifnum == NI_LOCAL)); if (prt == NULL) { if (gateway) { iph2net(pip); icmp(ICT_DESTUR, ICC_NETUR, pip->ip_src, pep); } else { IpOutNoRoutes++; freebuf(pep); } continue; } nonlocal = ifnum != NI_LOCAL && prt->rt_ifnum != NI_LOCAL; if (!gateway && nonlocal) { IpInAddrErrors++; freebuf(pep); rtfree(prt); continue; } if (nonlocal) IpForwDatagrams++; /* fill in src IP, if we're the sender */ if (ifnum == NI_LOCAL) if (blkequ(pip->ip_src, ip_anyaddr, IP_ALEN)) if (prt->rt_ifnum == NI_LOCAL) blkcopy(pip->ip_src, pip->ip_dst, IP_ALEN); else blkcopy(pip->ip_src, nif[prt->rt_ifnum].ni_ip, IP_ALEN); if (--(pip->ip_ttl) == 0 && prt->rt_ifnum != NI_LOCAL) { IpInHdrErrors++; iph2net(pip); icmp(ICT_TIMEX, ICC_TIMEX, pip->ip_src, pep); rtfree(prt); continue; } ipdbc(ifnum, pep, prt); /* handle directed broadcasts */ ipredirect(pep, ifnum, prt); /* do redirect, if needed */ if (prt->rt_metric != 0) ipputp(prt->rt_ifnum, prt->rt_gw, pep); else ipputp(prt->rt_ifnum, pip->ip_dst, pep); rtfree(prt); } } int ippid, gateway, bsdbrc;