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-rw-r--r--common/bpf.c609
1 files changed, 609 insertions, 0 deletions
diff --git a/common/bpf.c b/common/bpf.c
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+++ b/common/bpf.c
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+/* bpf.c
+
+ BPF socket interface code, originally contributed by Archie Cobbs. */
+
+/*
+ * Copyright (c) 2004,2007,2009 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 1996-2003 by Internet Software Consortium
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * 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.
+ * 950 Charter Street
+ * Redwood City, CA 94063
+ * <info@isc.org>
+ * https://www.isc.org/
+ *
+ * This software was contributed to Internet Systems Consortium
+ * by Archie Cobbs.
+ *
+ * Patches for FDDI support on Digital Unix were written by Bill
+ * Stapleton, and maintained for a while by Mike Meredith before he
+ * managed to get me to integrate them.
+ */
+
+#include "dhcpd.h"
+#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) \
+ || defined (USE_LPF_RECEIVE)
+# if defined (USE_LPF_RECEIVE)
+# include <asm/types.h>
+# include <linux/filter.h>
+# define bpf_insn sock_filter /* Linux: dare to be gratuitously different. */
+# else
+# include <sys/ioctl.h>
+# include <sys/uio.h>
+# include <net/bpf.h>
+# include <net/if_types.h>
+# if defined (NEED_OSF_PFILT_HACKS)
+# include <net/pfilt.h>
+# endif
+# endif
+
+#include <netinet/in_systm.h>
+#include "includes/netinet/ip.h"
+#include "includes/netinet/udp.h"
+#include "includes/netinet/if_ether.h"
+#endif
+
+#ifdef USE_BPF_RECEIVE
+#include <ifaddrs.h>
+#endif
+
+#include <errno.h>
+
+/* Reinitializes the specified interface after an address change. This
+ is not required for packet-filter APIs. */
+
+#ifdef USE_BPF_SEND
+void if_reinitialize_send (info)
+ struct interface_info *info;
+{
+}
+#endif
+
+#ifdef USE_BPF_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. */
+
+#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE)
+int if_register_bpf (info)
+ struct interface_info *info;
+{
+ int sock;
+ char filename[50];
+ int b;
+
+ /* Open a BPF device */
+ for (b = 0; 1; b++) {
+ /* %Audit% 31 bytes max. %2004.06.17,Safe% */
+ sprintf(filename, BPF_FORMAT, b);
+ sock = open (filename, O_RDWR, 0);
+ if (sock < 0) {
+ if (errno == EBUSY) {
+ continue;
+ } else {
+ if (!b)
+ log_fatal ("No bpf devices.%s%s%s",
+ " Please read the README",
+ " section for your operating",
+ " system.");
+ log_fatal ("Can't find free bpf: %m");
+ }
+ } else {
+ break;
+ }
+ }
+
+ /* Set the BPF device to point at this interface. */
+ if (ioctl (sock, BIOCSETIF, info -> ifp) < 0)
+ log_fatal ("Can't attach interface %s to bpf device %s: %m",
+ info -> name, filename);
+
+ get_hw_addr(info->name, &info->hw_address);
+
+ return sock;
+}
+#endif /* USE_BPF_SEND || USE_BPF_RECEIVE */
+
+#ifdef USE_BPF_SEND
+void if_register_send (info)
+ struct interface_info *info;
+{
+ /* If we're using the bpf API for sending and receiving,
+ we don't need to register this interface twice. */
+#ifndef USE_BPF_RECEIVE
+ info -> wfdesc = if_register_bpf (info, interface);
+#else
+ info -> wfdesc = info -> rfdesc;
+#endif
+ if (!quiet_interface_discovery)
+ log_info ("Sending on BPF/%s/%s%s%s",
+ info -> name,
+ 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 bpf API for sending and receiving,
+ we don't need to register this interface twice. */
+#ifndef USE_BPF_RECEIVE
+ close (info -> wfdesc);
+#endif
+ info -> wfdesc = -1;
+
+ if (!quiet_interface_discovery)
+ log_info ("Disabling output on BPF/%s/%s%s%s",
+ info -> name,
+ 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_BPF_SEND */
+
+#if defined (USE_BPF_RECEIVE) || defined (USE_LPF_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 BPF program! XXX */
+
+struct bpf_insn dhcp_bpf_filter [] = {
+ /* Make sure this is an IP packet... */
+ BPF_STMT (BPF_LD + BPF_H + BPF_ABS, 12),
+ BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8),
+
+ /* Make sure it's a UDP packet... */
+ BPF_STMT (BPF_LD + BPF_B + BPF_ABS, 23),
+ BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6),
+
+ /* Make sure this isn't a fragment... */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
+ BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0),
+
+ /* Get the IP header length... */
+ BPF_STMT (BPF_LDX + BPF_B + BPF_MSH, 14),
+
+ /* Make sure it's to the right port... */
+ BPF_STMT (BPF_LD + BPF_H + BPF_IND, 16),
+ BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1), /* patch */
+
+ /* If we passed all the tests, ask for the whole packet. */
+ BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
+
+ /* Otherwise, drop it. */
+ BPF_STMT(BPF_RET+BPF_K, 0),
+};
+
+#if defined (DEC_FDDI)
+struct bpf_insn *bpf_fddi_filter;
+#endif
+
+int dhcp_bpf_filter_len = sizeof dhcp_bpf_filter / sizeof (struct bpf_insn);
+#if defined (HAVE_TR_SUPPORT)
+struct bpf_insn dhcp_bpf_tr_filter [] = {
+ /* accept all token ring packets due to variable length header */
+ /* if we want to get clever, insert the program here */
+
+ /* If we passed all the tests, ask for the whole packet. */
+ BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
+
+ /* Otherwise, drop it. */
+ BPF_STMT(BPF_RET+BPF_K, 0),
+};
+
+int dhcp_bpf_tr_filter_len = (sizeof dhcp_bpf_tr_filter /
+ sizeof (struct bpf_insn));
+#endif /* HAVE_TR_SUPPORT */
+#endif /* USE_LPF_RECEIVE || USE_BPF_RECEIVE */
+
+#if defined (USE_BPF_RECEIVE)
+void if_register_receive (info)
+ struct interface_info *info;
+{
+ int flag = 1;
+ struct bpf_version v;
+ struct bpf_program p;
+#ifdef NEED_OSF_PFILT_HACKS
+ u_int32_t bits;
+#endif
+#ifdef DEC_FDDI
+ int link_layer;
+#endif /* DEC_FDDI */
+
+ /* Open a BPF device and hang it on this interface... */
+ info -> rfdesc = if_register_bpf (info);
+
+ /* Make sure the BPF version is in range... */
+ if (ioctl (info -> rfdesc, BIOCVERSION, &v) < 0)
+ log_fatal ("Can't get BPF version: %m");
+
+ if (v.bv_major != BPF_MAJOR_VERSION ||
+ v.bv_minor < BPF_MINOR_VERSION)
+ log_fatal ("BPF version mismatch - recompile DHCP!");
+
+ /* Set immediate mode so that reads return as soon as a packet
+ comes in, rather than waiting for the input buffer to fill with
+ packets. */
+ if (ioctl (info -> rfdesc, BIOCIMMEDIATE, &flag) < 0)
+ log_fatal ("Can't set immediate mode on bpf device: %m");
+
+#ifdef NEED_OSF_PFILT_HACKS
+ /* Allow the copyall flag to be set... */
+ if (ioctl(info -> rfdesc, EIOCALLOWCOPYALL, &flag) < 0)
+ log_fatal ("Can't set ALLOWCOPYALL: %m");
+
+ /* Clear all the packet filter mode bits first... */
+ bits = 0;
+ if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
+ log_fatal ("Can't clear pfilt bits: %m");
+
+ /* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */
+ bits = ENBATCH | ENCOPYALL | ENBPFHDR;
+ if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
+ log_fatal ("Can't set ENBATCH|ENCOPYALL|ENBPFHDR: %m");
+#endif
+ /* Get the required BPF buffer length from the kernel. */
+ if (ioctl (info -> rfdesc, BIOCGBLEN, &info -> rbuf_max) < 0)
+ log_fatal ("Can't get bpf buffer length: %m");
+ info -> rbuf = dmalloc (info -> rbuf_max, MDL);
+ if (!info -> rbuf)
+ log_fatal ("Can't allocate %ld bytes for bpf input buffer.",
+ (long)(info -> rbuf_max));
+ info -> rbuf_offset = 0;
+ info -> rbuf_len = 0;
+
+ /* Set up the bpf filter program structure. */
+ p.bf_len = dhcp_bpf_filter_len;
+
+#ifdef DEC_FDDI
+ /* See if this is an FDDI interface, flag it for later. */
+ if (ioctl(info -> rfdesc, BIOCGDLT, &link_layer) >= 0 &&
+ link_layer == DLT_FDDI) {
+ if (!bpf_fddi_filter) {
+ bpf_fddi_filter = dmalloc (sizeof bpf_fddi_filter,
+ MDL);
+ if (!bpf_fddi_filter)
+ log_fatal ("No memory for FDDI filter.");
+ memcpy (bpf_fddi_filter,
+ dhcp_bpf_filter, sizeof dhcp_bpf_filter);
+ /* Patch the BPF program to account for the difference
+ in length between ethernet headers (14), FDDI and
+ 802.2 headers (16 +8=24, +10).
+ XXX changes to filter program may require changes to
+ XXX the insn number(s) used below! */
+ bpf_fddi_filter[0].k += 10;
+ bpf_fddi_filter[2].k += 10;
+ bpf_fddi_filter[4].k += 10;
+ bpf_fddi_filter[6].k += 10;
+ bpf_fddi_filter[7].k += 10;
+ }
+ p.bf_insns = bpf_fddi_filter;
+ } else
+#endif /* DEC_FDDI */
+ p.bf_insns = dhcp_bpf_filter;
+
+ /* Patch the server port into the BPF program...
+ XXX changes to filter program may require changes
+ to the insn number(s) used below! XXX */
+ dhcp_bpf_filter [8].k = ntohs (local_port);
+
+ if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0)
+ log_fatal ("Can't install packet filter program: %m");
+ if (!quiet_interface_discovery)
+ log_info ("Listening on BPF/%s/%s%s%s",
+ info -> name,
+ 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;
+{
+ close (info -> rfdesc);
+ info -> rfdesc = -1;
+
+ if (!quiet_interface_discovery)
+ log_info ("Disabling input on BPF/%s/%s%s%s",
+ info -> name,
+ 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_BPF_RECEIVE */
+
+#ifdef USE_BPF_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 = 0, ibufp = 0;
+ double hw [4];
+ double ip [32];
+ struct iovec iov [3];
+ 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;
+
+ /* Assemble the headers... */
+ assemble_hw_header (interface, (unsigned char *)hw, &hbufp, hto);
+ assemble_udp_ip_header (interface,
+ (unsigned char *)ip, &ibufp, from.s_addr,
+ to -> sin_addr.s_addr, to -> sin_port,
+ (unsigned char *)raw, len);
+
+ /* Fire it off */
+ iov [0].iov_base = ((char *)hw);
+ iov [0].iov_len = hbufp;
+ iov [1].iov_base = ((char *)ip);
+ iov [1].iov_len = ibufp;
+ iov [2].iov_base = (char *)raw;
+ iov [2].iov_len = len;
+
+ result = writev(interface -> wfdesc, iov, 3);
+ if (result < 0)
+ log_error ("send_packet: %m");
+ return result;
+}
+#endif /* USE_BPF_SEND */
+
+#ifdef USE_BPF_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 length = 0;
+ int offset = 0;
+ struct bpf_hdr hdr;
+ unsigned paylen;
+
+ /* All this complexity is because BPF doesn't guarantee
+ that only one packet will be returned at a time. We're
+ getting what we deserve, though - this is a terrible abuse
+ of the BPF interface. Sigh. */
+
+ /* Process packets until we get one we can return or until we've
+ done a read and gotten nothing we can return... */
+
+ do {
+ /* If the buffer is empty, fill it. */
+ if (interface -> rbuf_offset == interface -> rbuf_len) {
+ length = read (interface -> rfdesc,
+ interface -> rbuf,
+ (size_t)interface -> rbuf_max);
+ if (length <= 0) {
+#ifdef __FreeBSD__
+ if (errno == ENXIO) {
+#else
+ if (errno == EIO) {
+#endif
+ dhcp_interface_remove
+ ((omapi_object_t *)interface,
+ (omapi_object_t *)0);
+ }
+ return length;
+ }
+ interface -> rbuf_offset = 0;
+ interface -> rbuf_len = BPF_WORDALIGN (length);
+ }
+
+ /* If there isn't room for a whole bpf header, something went
+ wrong, but we'll ignore it and hope it goes away... XXX */
+ if (interface -> rbuf_len -
+ interface -> rbuf_offset < sizeof hdr) {
+ interface -> rbuf_offset = interface -> rbuf_len;
+ continue;
+ }
+
+ /* Copy out a bpf header... */
+ memcpy (&hdr, &interface -> rbuf [interface -> rbuf_offset],
+ sizeof hdr);
+
+ /* If the bpf header plus data doesn't fit in what's left
+ of the buffer, stick head in sand yet again... */
+ if (interface -> rbuf_offset +
+ hdr.bh_hdrlen + hdr.bh_caplen > interface -> rbuf_len) {
+ interface -> rbuf_offset = interface -> rbuf_len;
+ continue;
+ }
+
+ /* If the captured data wasn't the whole packet, or if
+ the packet won't fit in the input buffer, all we
+ can do is drop it. */
+ if (hdr.bh_caplen != hdr.bh_datalen) {
+ interface -> rbuf_offset =
+ BPF_WORDALIGN (interface -> rbuf_offset +
+ hdr.bh_hdrlen + hdr.bh_caplen);
+ continue;
+ }
+
+ /* Skip over the BPF header... */
+ interface -> rbuf_offset += hdr.bh_hdrlen;
+
+ /* Decode the physical header... */
+ offset = decode_hw_header (interface,
+ interface -> rbuf,
+ interface -> rbuf_offset,
+ hfrom);
+
+ /* If a physical layer checksum failed (dunno of any
+ physical layer that supports this, but WTH), skip this
+ packet. */
+ if (offset < 0) {
+ interface -> rbuf_offset =
+ BPF_WORDALIGN (interface -> rbuf_offset +
+ hdr.bh_caplen);
+ continue;
+ }
+ interface -> rbuf_offset += offset;
+ hdr.bh_caplen -= offset;
+
+ /* Decode the IP and UDP headers... */
+ offset = decode_udp_ip_header (interface,
+ interface -> rbuf,
+ interface -> rbuf_offset,
+ from, hdr.bh_caplen, &paylen);
+
+ /* If the IP or UDP checksum was bad, skip the packet... */
+ if (offset < 0) {
+ interface -> rbuf_offset =
+ BPF_WORDALIGN (interface -> rbuf_offset +
+ hdr.bh_caplen);
+ continue;
+ }
+ interface -> rbuf_offset = interface -> rbuf_offset + offset;
+ hdr.bh_caplen -= offset;
+
+ /* If there's not enough room to stash the packet data,
+ we have to skip it (this shouldn't happen in real
+ life, though). */
+ if (hdr.bh_caplen > len) {
+ interface -> rbuf_offset =
+ BPF_WORDALIGN (interface -> rbuf_offset +
+ hdr.bh_caplen);
+ continue;
+ }
+
+ /* Copy out the data in the packet... */
+ memcpy(buf, interface->rbuf + interface->rbuf_offset, paylen);
+ interface -> rbuf_offset =
+ BPF_WORDALIGN (interface -> rbuf_offset +
+ hdr.bh_caplen);
+ return paylen;
+ } while (!length);
+ return 0;
+}
+
+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);
+ }
+}
+
+void
+get_hw_addr(const char *name, struct hardware *hw) {
+ struct ifaddrs *ifa;
+ struct ifaddrs *p;
+ struct sockaddr_dl *sa;
+
+ if (getifaddrs(&ifa) != 0) {
+ log_fatal("Error getting interface information; %m");
+ }
+
+ /*
+ * Loop through our interfaces finding a match.
+ */
+ sa = NULL;
+ for (p=ifa; (p != NULL) && (sa == NULL); p = p->ifa_next) {
+ if ((p->ifa_addr->sa_family == AF_LINK) &&
+ !strcmp(p->ifa_name, name)) {
+ sa = (struct sockaddr_dl *)p->ifa_addr;
+ }
+ }
+ if (sa == NULL) {
+ log_fatal("No interface called '%s'", name);
+ }
+
+ /*
+ * Pull out the appropriate information.
+ */
+ switch (sa->sdl_type) {
+ case IFT_ETHER:
+ hw->hlen = sa->sdl_alen + 1;
+ hw->hbuf[0] = HTYPE_ETHER;
+ memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
+ break;
+ case IFT_ISO88023:
+ case IFT_ISO88024: /* "token ring" */
+ case IFT_ISO88025:
+ case IFT_ISO88026:
+ hw->hlen = sa->sdl_alen + 1;
+ hw->hbuf[0] = HTYPE_IEEE802;
+ memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
+ break;
+#ifdef IFT_FDDI
+ case IFT_FDDI:
+ hw->hlen = sa->sdl_alen + 1;
+ hw->hbuf[0] = HTYPE_FDDI;
+ memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
+ break;
+#endif /* IFT_FDDI */
+ default:
+ log_fatal("Unsupported device type %d for \"%s\"",
+ sa->sdl_type, name);
+ }
+
+ freeifaddrs(ifa);
+}
+#endif