/* $NetBSD: nit.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $ */ /* nit.c Network Interface Tap (NIT) network interface code, by Ted Lemon with one crucial tidbit of help from Stu Grossmen. */ /* * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996-2003 by Internet Software Consortium * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Internet Systems Consortium, Inc. * PO Box 360 * Newmarket, NH 03857 USA * * https://www.isc.org/ * */ #include __RCSID("$NetBSD: nit.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $"); #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) log_fatal ("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) log_fatal ("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) log_fatal ("Can't get physical layer address for %s: %m", info -> name); /* XXX code below assumes ethernet interface! */ info -> hw_address.hlen = 7; info -> hw_address.hbuf [0] = ARPHRD_ETHER; memcpy (&info -> hw_address.hbuf [1], ifr.ifr_ifru.ifru_addr.sa_data, 6); if (ioctl (sock, I_PUSH, "pf") < 0) log_fatal ("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) log_fatal ("Can't set NIT filter: %m"); #else info -> wfdesc = info -> rfdesc; #endif if (!quiet_interface_discovery) log_info ("Sending on NIT/%s%s%s", print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } void if_deregister_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 close (info -> wfdesc); #endif info -> wfdesc = -1; if (!quiet_interface_discovery) log_info ("Disabling output on NIT/%s%s%s", print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } #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 */ #if defined(RELAY_PORT) #error "Relay port is not yet supported for NIT" #endif 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) log_fatal ("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) log_info ("I_SRDOPT failed on %s: %m", info -> name); #if 0 /* Push on the chunker... */ if (ioctl (info -> rfdesc, I_PUSH, "nbuf") < 0) log_fatal ("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) log_fatal ("Can't set chunk timeout: %m"); #endif /* Ask for no header... */ x = 0; if (ioctl (info -> rfdesc, NIOCSFLAGS, &x) < 0) log_fatal ("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++] = *libdhcp_callbacks.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) log_fatal ("Can't set NIT filter on %s: %m", info -> name); if (!quiet_interface_discovery) log_info ("Listening on NIT/%s%s%s", print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } void if_deregister_receive (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. */ close (info -> rfdesc); info -> rfdesc = -1; if (!quiet_interface_discovery) log_info ("Disabling input on NIT/%s%s%s", print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } #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; { unsigned hbufp, ibufp; double hh [16]; double ih [1536 / sizeof (double)]; unsigned char *buf = (unsigned char *)ih; struct sockaddr *junk; struct strbuf ctl, data; struct sockaddr_in foo; int result; if (!strcmp (interface -> name, "fallback")) return send_fallback (interface, packet, raw, len, from, to, hto); if (hto == NULL && interface->anycast_mac_addr.hlen) hto = &interface->anycast_mac_addr; /* Start with the sockaddr struct... */ junk = (struct sockaddr *)&hh [0]; hbufp = (((unsigned char *)&junk -> sa_data [0]) - (unsigned char *)&hh[0]); ibufp = 0; /* Assemble the headers... */ assemble_hw_header (interface, (unsigned char *)junk, &hbufp, hto); assemble_udp_ip_header (interface, buf, &ibufp, from.s_addr, to -> sin_addr.s_addr, to -> sin_port, (unsigned char *)raw, len); /* Copy the data into the buffer (yuk). */ memcpy (buf + ibufp, raw, len); /* Set up the sockaddr structure... */ #if USE_SIN_LEN junk -> sa_len = hbufp - 2; /* XXX */ #endif junk -> sa_family = AF_UNSPEC; /* Set up the msg_buf structure... */ ctl.buf = (char *)&hh [0]; ctl.maxlen = ctl.len = hbufp; data.buf = (char *)&ih [0]; data.maxlen = data.len = ibufp + len; result = putmsg (interface -> wfdesc, &ctl, &data, 0); if (result < 0) log_error ("send_packet: %m"); return result; } #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; unsigned paylen; 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, length, &paylen, 1); /* If the IP or UDP checksum was bad, skip the packet... */ if (offset < 0) return 0; bufix += offset; length -= offset; if (length < paylen) log_fatal("Internal inconsistency at %s:%d.", MDL); /* Copy out the data in the packet... */ memcpy(buf, &ibuf[bufix], paylen); return paylen; } int can_unicast_without_arp (ip) struct interface_info *ip; { return 1; } int can_receive_unicast_unconfigured (ip) struct interface_info *ip; { return 1; } int supports_multiple_interfaces (ip) struct interface_info *ip; { return 1; } void maybe_setup_fallback () { isc_result_t status; struct interface_info *fbi = (struct interface_info *)0; if (setup_fallback (&fbi, MDL)) { if_register_fallback (fbi); status = omapi_register_io_object ((omapi_object_t *)fbi, if_readsocket, 0, fallback_discard, 0, 0); if (status != ISC_R_SUCCESS) log_fatal ("Can't register I/O handle for %s: %s", fbi -> name, isc_result_totext (status)); interface_dereference (&fbi, MDL); } } #endif