ip_read.c

minux的源代码,一个非常小的操作系统

	{
#if DEBUG
 { where(); where(); printf("fragment not allright\n"); }
#endif
		bf_afree(ip_acc);
		bf_afree(eth_acc);
		return;
	}
	for_this_port= ok_for_port(ip_port, ip_hdr->ih_dst,
		&broadcast_allowed);

	if (!broadcast_allowed && broadcast_pack)
	{
		printf("got eth-broadcast pack for ip-nonbroadcast addr, src=");
		writeIpAddr(ip_hdr->ih_src);
		printf(" dst=");
		writeIpAddr(ip_hdr->ih_dst);
		printf("\n");
		bf_afree(ip_acc);
		bf_afree(eth_acc);
		return;
	}
#if !IP_ROUTER
	if (!for_this_port)
	{
#if DEBUG
 { where(); printf("ip.c: got strange packet, src="); 
   writeIpAddr(ip_hdr->ih_src); printf(" dst="); writeIpAddr(ip_hdr->ih_dst);
   printf(" src_eth= "); writeEtherAddr(&eth_src); printf(" dst_eth= ");
   writeEtherAddr(&eth_dst); printf("\n"); }
#endif
		bf_afree(ip_acc);
		bf_afree(eth_acc);
		return;
	}
#else
	if (!for_this_port)
	{
		bf_afree(eth_acc);
		ip_route(ip_port, ip_acc);
		return;
	}
#endif /* !IP_ROUTER */
	bf_afree(eth_acc);
	if (ntohs(ip_hdr->ih_flags_fragoff) & (IH_FRAGOFF_MASK|IH_MORE_FRAGS))
	{
#if DEBUG & 256
 { where(); printf("reassembling\n"); }
#endif
		ip_acc= reassemble (ip_port, ip_acc, ip_hdr);
		if (!ip_acc)
			return;
assert (ip_acc->acc_length >= IP_MIN_HDR_SIZE);
	ip_hdr= (ip_hdr_t *)ptr2acc_data(ip_acc);
assert (!(ntohs(ip_hdr->ih_flags_fragoff) & (IH_FRAGOFF_MASK|IH_MORE_FRAGS)));
	}
	ip_port_arrive (ip_port, ip_acc, ip_hdr);
}

PRIVATE int ok_for_port (ip_port, ipaddr, ref_broad_all)
ip_port_t *ip_port;
ipaddr_t ipaddr;
int *ref_broad_all;
{
	ipaddr_t netmask;

#if DEBUG & 256
 { where(); printf("ok_for_port( .., "); writeIpAddr(ipaddr);
   printf(", ..)\nip_port->ip_ipaddr= "); 
   writeIpAddr(ip_port->ip_ipaddr); printf("\n"); }
#endif
	if (ipaddr == ip_port->ip_ipaddr)
		*ref_broad_all= FALSE;
	else if (ipaddr == (ipaddr_t)-1)
		*ref_broad_all= TRUE;
	else if (net_broad (ipaddr, ip_port->ip_ipaddr &
		ip_port->ip_netmask, ip_port->ip_netmask))
		*ref_broad_all= TRUE;
	else
	{
		netmask= ip_get_netmask(ipaddr);
		if (!net_broad (ipaddr, ip_port->ip_ipaddr & netmask,
			netmask))
			return FALSE;
		*ref_broad_all= TRUE;
	}
	return TRUE;
}

PRIVATE int ip_frag_chk(pack)
acc_t *pack;
{
	ip_hdr_t *ip_hdr;
	int hdr_len;

	if (pack->acc_length < sizeof(ip_hdr_t))
	{
#if DEBUG
 { where(); printf("wrong length\n"); }
#endif
		return FALSE;
	}

	ip_hdr= (ip_hdr_t *)ptr2acc_data(pack);

	hdr_len= (ip_hdr->ih_vers_ihl & IH_IHL_MASK) * 4;
	if (pack->acc_length < hdr_len)
	{
#if DEBUG
 { where(); printf("wrong length\n"); }
#endif
		return FALSE;
	}

	if (((ip_hdr->ih_vers_ihl >> 4) & IH_VERSION_MASK) !=
		IP_VERSION)
	{
#if DEBUG
 { where(); printf("wrong version (ih_vers_ihl=0x%x)\n",ip_hdr->ih_vers_ihl); }
#endif
		return FALSE;
	}
	if (ntohs(ip_hdr->ih_length) != bf_bufsize(pack))
	{
#if DEBUG
 { where(); printf("wrong size\n"); }
#endif
		return FALSE;
	}
	if ((u16_t)~oneC_sum(0, (u16_t *)ip_hdr, hdr_len))
	{
#if DEBUG
 { where(); printf("packet with wrong checksum (= %x)\n", 
   (u16_t)~oneC_sum(0, (u16_t *)ip_hdr, hdr_len)); }
#endif
		return FALSE;
	}
	if (hdr_len>IP_MIN_HDR_SIZE && ip_chk_hdropt((u8_t *)
		(ptr2acc_data(pack) + IP_MIN_HDR_SIZE),
		hdr_len-IP_MIN_HDR_SIZE))
	{
#if DEBUG
 { where(); printf("packet with wrong options\n"); }
#endif
		return FALSE;
	}
	return TRUE;
}

PRIVATE int net_broad (hostaddr, netaddr, netmask)
ipaddr_t hostaddr, netaddr, netmask;
{
	if ((hostaddr & netmask) != (netaddr & netmask))
		return FALSE;
	if ((hostaddr & ~netmask) == ~netmask)
		return TRUE;
#if IP_SUN_BROADCAST
	if ((hostaddr & ~netmask) == 0)
		return TRUE;
#endif
	return FALSE;
}

PUBLIC int ip_packet2user (ip_fd)
ip_fd_t *ip_fd;
{
	acc_t *pack, *tmp_pack;
	ip_hdr_t *hdr;
	int result, hdr_len;
	size_t size, transf_size;

	pack= ip_fd->if_rd_buf;
	ip_fd->if_rd_buf= 0;

	size= bf_bufsize (pack);

	if (ip_fd->if_ipopt.nwio_flags & NWIO_RWDATONLY)
	{

		pack= bf_packIffLess (pack, IP_MIN_HDR_SIZE);
		assert (pack->acc_length >= IP_MIN_HDR_SIZE);

		hdr= (ip_hdr_t *)ptr2acc_data(pack);
		hdr_len= (hdr->ih_vers_ihl & IH_IHL_MASK) * 4;

		assert (size>= hdr_len);
		size -= hdr_len;
		tmp_pack= bf_cut(pack, hdr_len, size);
		bf_afree(pack);
		pack= tmp_pack;
	}

	if (size>ip_fd->if_rd_count)
	{
		tmp_pack= bf_cut (pack, 0, ip_fd->if_rd_count);
		bf_afree(pack);
		pack= tmp_pack;
		transf_size= ip_fd->if_rd_count;
	}
	else
		transf_size= size;

	result= (*ip_fd->if_put_userdata)(ip_fd->if_srfd,
		(size_t)0, pack, FALSE);
	if (result >= 0)
		if (size > transf_size)
			result= EPACKSIZE;
		else
			result= transf_size;

#if DEBUG & 256
 { where(); printf("packet2user cleared IFF_READ_IP\n"); }
#endif
	ip_fd->if_flags &= ~IFF_READ_IP;
	result= (*ip_fd->if_put_userdata)(ip_fd->if_srfd, result,
			(acc_t *)0, FALSE);
	assert (result >= 0);

	return result;
}

PUBLIC int ip_ok_for_fd (ip_fd, pack)
ip_fd_t *ip_fd;
acc_t *pack;
{
	ip_port_t *ip_port;
	ip_hdr_t *hdr;
	ipaddr_t dst;
	unsigned long pack_kind, nwio_flags;


	assert (pack->acc_length >= IP_MIN_HDR_SIZE);

	ip_port= ip_fd->if_port;

	hdr= (ip_hdr_t *)ptr2acc_data(pack);
	dst= hdr->ih_dst;
	if (dst == ip_port->ip_ipaddr)
		pack_kind= NWIO_EN_LOC;
	else
		pack_kind= NWIO_DI_LOC;

	nwio_flags= ip_fd->if_ipopt.nwio_flags;
	if (!(pack_kind & nwio_flags))
		return FALSE;

	if ((nwio_flags & NWIO_PROTOSPEC) &&
		(hdr->ih_proto != ip_fd->if_ipopt.nwio_proto))
		return FALSE;

	if ((nwio_flags & NWIO_REMSPEC) &&
		(hdr->ih_src != ip_fd->if_ipopt.nwio_rem))
		return FALSE;

	return TRUE;
}

PUBLIC void ip_port_arrive (ip_port, pack, ip_hdr)
ip_port_t *ip_port;
acc_t *pack;
ip_hdr_t *ip_hdr;
{
	ip_fd_t *ip_fd, *share_fd;
	ip_hdr_t *hdr;
	int port_nr;
	unsigned long ip_pack_stat;
	int i;
	ipproto_t proto;
	time_t exp_tim;

assert (pack->acc_linkC>0);

#if DEBUG & 256
 { where(); printf ("in ip_port_arrive()\n"); }
#endif
assert (pack->acc_length >= IP_MIN_HDR_SIZE);

	exp_tim= get_time() + (ip_hdr->ih_ttl+1) * HZ;

	if (ip_hdr->ih_dst == ip_port->ip_ipaddr)
		ip_pack_stat= NWIO_EN_LOC;
	else
		ip_pack_stat= NWIO_EN_BROAD;

	proto= ip_hdr->ih_proto;

#if DEBUG & 256
 { where(); printf("proto= %d\n", proto); }
#endif

	share_fd= 0;
	for (i=0, ip_fd=ip_fd_table; i<IP_FD_NR; i++, ip_fd++)
	{
		if (!(ip_fd->if_flags & IFF_INUSE))
		{
			continue;
		}
#if DEBUG & 256
 { where(); printf("ip_fd_table[%d].if_flags= 0x%x\n",
	ip_fd-ip_fd_table, ip_fd->if_flags); }
#endif
		if (!(ip_fd->if_flags & IFF_OPTSET))
		{
#if DEBUG & 256
 { where(); printf("%d options not set\n", i); }
#endif
			continue;
		}
		if (ip_fd->if_port != ip_port)
		{
#if DEBUG
 { where(); printf("%d wrong port\n", i); }
#endif
			continue;
		}
		if (!(ip_fd->if_ipopt.nwio_flags & ip_pack_stat))
		{
#if DEBUG & 256
 { where(); printf("%d wrong ip_pack_stat\n", i); }
#endif
			continue;
		}
		if ((ip_fd->if_ipopt.nwio_flags & NWIO_PROTOSPEC) &&
			proto != ip_fd->if_ipopt.nwio_proto)
		{
#if DEBUG & 256
 { where(); printf("%d wrong proto\n", i); }
#endif
			continue;
		}
		if ((ip_fd->if_ipopt.nwio_flags & NWIO_REMSPEC) &&
			ip_hdr->ih_src != ip_fd->if_ipopt.nwio_rem)
		{
#if DEBUG
 { where(); printf("%d wrong src addr (REMSPEC)\n", i); }
#endif
			continue;
		}
		if (ip_fd->if_rd_buf)
		{
			if ((ip_fd->if_ipopt.nwio_flags &
				NWIO_ACC_MASK) == NWIO_SHARED)
			{
#if DEBUG
 { where(); printf("%d shared packet\n", i); }
#endif
				share_fd= ip_fd;
				continue;
			}
#if DEBUG
 { where(); printf("throwing away packet\n"); }
#endif
			bf_afree(ip_fd->if_rd_buf);
		}
		ip_fd->if_rd_buf= pack;
		pack->acc_linkC++;
		ip_fd->if_exp_tim= exp_tim;

		if ((ip_fd->if_ipopt.nwio_flags & NWIO_ACC_MASK) == 
			NWIO_SHARED || (ip_fd->if_ipopt.nwio_flags &
			NWIO_ACC_MASK) ==  NWIO_EXCL)
		{
#if DEBUG
 { where(); printf("exclusive packet\n"); }
#endif
			bf_afree(pack);
			pack= 0;
			break;
		}

		if (ip_fd->if_flags & IFF_READ_IP)
		{
#if DEBUG & 256
 { where(); printf("%d calling packet2user\n", i); }
#endif
			ip_packet2user(ip_fd);
		}
		else
		{
#if DEBUG
 { where(); printf("%d not READ_IP\n", i); }
#endif
		}
	}
	if (share_fd && pack)
	{
#if DEBUG
 { where(); printf("exclusive packet\n"); }
#endif
		bf_afree(share_fd->if_rd_buf);
		share_fd->if_rd_buf= pack;
		share_fd->if_exp_tim= exp_tim;
	}
	else
	{
#if DEBUG & 256
 { where(); printf("throwing away packet\n"); }
#endif
		if (pack)
			bf_afree(pack);
	}
}