/* nit.c Network Interface Tap (NIT) network interface code, by Ted Lemon with one crucial tidbit of help from Stu Grossmen. */ /* * Copyright (c) 1996 The Internet Software Consortium. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of The Internet Software Consortium nor the names * of its contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * This software has been written for the Internet Software Consortium * by Ted Lemon in cooperation with Vixie * Enterprises. To learn more about the Internet Software Consortium, * see ``http://www.vix.com/isc''. To learn more about Vixie * Enterprises, see ``http://www.vix.com''. */ #ifndef lint static char copyright[] = "$Id: nit.c,v 1.1.1.3 1997/10/20 23:28:40 mellon Exp $ Copyright (c) 1996 The Internet Software Consortium. All rights reserved.\n"; #endif /* not lint */ #include "dhcpd.h" #if defined (USE_NIT_SEND) || defined (USE_NIT_RECEIVE) #include #include #include #include #include #include #include #include #include #include #include "includes/netinet/ip.h" #include "includes/netinet/udp.h" #include "includes/netinet/if_ether.h" /* Reinitializes the specified interface after an address change. This is not required for packet-filter APIs. */ #ifdef USE_NIT_SEND void if_reinitialize_send (info) struct interface_info *info; { } #endif #ifdef USE_NIT_RECEIVE void if_reinitialize_receive (info) struct interface_info *info; { } #endif /* Called by get_interface_list for each interface that's discovered. Opens a packet filter for each interface and adds it to the select mask. */ int if_register_nit (info) struct interface_info *info; { int sock; char filename[50]; struct ifreq ifr; struct strioctl sio; /* Open a NIT device */ sock = open ("/dev/nit", O_RDWR); if (sock < 0) error ("Can't open NIT device for %s: %m", info -> name); /* Set the NIT device to point at this interface. */ sio.ic_cmd = NIOCBIND; sio.ic_len = sizeof *(info -> ifp); sio.ic_dp = (char *)(info -> ifp); sio.ic_timout = INFTIM; if (ioctl (sock, I_STR, &sio) < 0) error ("Can't attach interface %s to nit device: %m", info -> name); /* Get the low-level address... */ sio.ic_cmd = SIOCGIFADDR; sio.ic_len = sizeof ifr; sio.ic_dp = (char *)𝔦 sio.ic_timout = INFTIM; if (ioctl (sock, I_STR, &sio) < 0) error ("Can't get physical layer address for %s: %m", info -> name); /* XXX code below assumes ethernet interface! */ info -> hw_address.hlen = 6; info -> hw_address.htype = ARPHRD_ETHER; memcpy (info -> hw_address.haddr, ifr.ifr_ifru.ifru_addr.sa_data, 6); if (ioctl (sock, I_PUSH, "pf") < 0) error ("Can't push packet filter onto NIT for %s: %m", info -> name); return sock; } #endif /* USE_NIT_SEND || USE_NIT_RECEIVE */ #ifdef USE_NIT_SEND void if_register_send (info) struct interface_info *info; { /* If we're using the nit API for sending and receiving, we don't need to register this interface twice. */ #ifndef USE_NIT_RECEIVE struct packetfilt pf; struct strioctl sio; info -> wfdesc = if_register_nit (info); pf.Pf_Priority = 0; pf.Pf_FilterLen = 1; pf.Pf_Filter [0] = ENF_PUSHZERO; /* Set up an NIT filter that rejects everything... */ sio.ic_cmd = NIOCSETF; sio.ic_len = sizeof pf; sio.ic_dp = (char *)&pf; sio.ic_timout = INFTIM; if (ioctl (info -> wfdesc, I_STR, &sio) < 0) error ("Can't set NIT filter: %m"); #else info -> wfdesc = info -> rfdesc; #endif if (!quiet_interface_discovery) note ("Sending on NIT/%s/%s", print_hw_addr (info -> hw_address.htype, info -> hw_address.hlen, info -> hw_address.haddr), (info -> shared_network ? info -> shared_network -> name : "unattached")); } #endif /* USE_NIT_SEND */ #ifdef USE_NIT_RECEIVE /* Packet filter program... XXX Changes to the filter program may require changes to the constant offsets used in if_register_send to patch the NIT program! XXX */ void if_register_receive (info) struct interface_info *info; { int flag = 1; u_int32_t x; struct packetfilt pf; struct strioctl sio; u_int16_t addr [2]; struct timeval t; /* Open a NIT device and hang it on this interface... */ info -> rfdesc = if_register_nit (info); /* Set the snap length to 0, which means always take the whole packet. */ x = 0; if (ioctl (info -> rfdesc, NIOCSSNAP, &x) < 0) error ("Can't set NIT snap length on %s: %m", info -> name); /* Set the stream to byte stream mode */ if (ioctl (info -> rfdesc, I_SRDOPT, RMSGN) != 0) note ("I_SRDOPT failed on %s: %m", info -> name); #if 0 /* Push on the chunker... */ if (ioctl (info -> rfdesc, I_PUSH, "nbuf") < 0) error ("Can't push chunker onto NIT STREAM: %m"); /* Set the timeout to zero. */ t.tv_sec = 0; t.tv_usec = 0; if (ioctl (info -> rfdesc, NIOCSTIME, &t) < 0) error ("Can't set chunk timeout: %m"); #endif /* Ask for no header... */ x = 0; if (ioctl (info -> rfdesc, NIOCSFLAGS, &x) < 0) error ("Can't set NIT flags on %s: %m", info -> name); /* Set up the NIT filter program. */ /* XXX Unlike the BPF filter program, this one won't work if the XXX IP packet is fragmented or if there are options on the IP XXX header. */ pf.Pf_Priority = 0; pf.Pf_FilterLen = 0; pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 6; pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND; pf.Pf_Filter [pf.Pf_FilterLen++] = htons (ETHERTYPE_IP); pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT; pf.Pf_Filter [pf.Pf_FilterLen++] = htons (IPPROTO_UDP); pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 11; pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_AND; pf.Pf_Filter [pf.Pf_FilterLen++] = htons (0xFF); pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_CAND; pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHWORD + 18; pf.Pf_Filter [pf.Pf_FilterLen++] = ENF_PUSHLIT + ENF_CAND; pf.Pf_Filter [pf.Pf_FilterLen++] = local_port; /* Install the filter... */ sio.ic_cmd = NIOCSETF; sio.ic_len = sizeof pf; sio.ic_dp = (char *)&pf; sio.ic_timout = INFTIM; if (ioctl (info -> rfdesc, I_STR, &sio) < 0) error ("Can't set NIT filter on %s: %m", info -> name); if (!quiet_interface_discovery) note ("Listening on NIT/%s/%s", print_hw_addr (info -> hw_address.htype, info -> hw_address.hlen, info -> hw_address.haddr), (info -> shared_network ? info -> shared_network -> name : "unattached")); } #endif /* USE_NIT_RECEIVE */ #ifdef USE_NIT_SEND ssize_t send_packet (interface, packet, raw, len, from, to, hto) struct interface_info *interface; struct packet *packet; struct dhcp_packet *raw; size_t len; struct in_addr from; struct sockaddr_in *to; struct hardware *hto; { int bufp; unsigned char buf [1536 + sizeof (struct sockaddr)]; struct sockaddr *junk; struct strbuf ctl, data; int hw_end; struct sockaddr_in foo; /* Start with the sockaddr struct... */ junk = (struct sockaddr *)&buf [0]; bufp = ((unsigned char *)&junk -> sa_data [0]) - &buf [0]; /* Assemble the headers... */ assemble_hw_header (interface, buf, &bufp, hto); hw_end = bufp; assemble_udp_ip_header (interface, buf, &bufp, from.s_addr, to -> sin_addr.s_addr, to -> sin_port, raw, len); /* Copy the data into the buffer (yuk). */ memcpy (buf + bufp, raw, len); /* Set up the sockaddr structure... */ #if USE_SIN_LEN junk -> sa_len = hw_end - 2; /* XXX */ #endif junk -> sa_family = AF_UNSPEC; #if 0 /* Already done. */ memcpy (junk.sa_data, buf, hw_len); #endif /* Set up the msg_buf structure... */ ctl.buf = (char *)&buf [0]; ctl.maxlen = ctl.len = hw_end; data.buf = (char *)&buf [hw_end]; data.maxlen = data.len = bufp + len - hw_end; return putmsg (interface -> wfdesc, &ctl, &data, 0); } #endif /* USE_NIT_SEND */ #ifdef USE_NIT_RECEIVE ssize_t receive_packet (interface, buf, len, from, hfrom) struct interface_info *interface; unsigned char *buf; size_t len; struct sockaddr_in *from; struct hardware *hfrom; { int nread; int length = 0; int offset = 0; unsigned char ibuf [1536]; int bufix = 0; length = read (interface -> rfdesc, ibuf, sizeof ibuf); if (length <= 0) return length; /* Decode the physical header... */ offset = decode_hw_header (interface, ibuf, bufix, hfrom); /* If a physical layer checksum failed (dunno of any physical layer that supports this, but WTH), skip this packet. */ if (offset < 0) { return 0; } bufix += offset; length -= offset; /* Decode the IP and UDP headers... */ offset = decode_udp_ip_header (interface, ibuf, bufix, from, (unsigned char *)0, length); /* If the IP or UDP checksum was bad, skip the packet... */ if (offset < 0) return 0; bufix += offset; length -= offset; /* Copy out the data in the packet... */ memcpy (buf, &ibuf [bufix], length); return length; } #endif