/*      $NetBSD: ndbootd-bpf.c,v 1.8 2004/12/01 23:18:20 christos Exp $ */

/* ndbootd-bpf.c - the Sun Network Disk (nd) daemon BPF component: */

/*
 * Copyright (c) 2001 Matthew Fredette.  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. All advertising materials mentioning features or use of this software
 *      must display the following acknowledgement:
 *        This product includes software developed by Matthew Fredette.
 *   4. The name of Matthew Fredette may not be used to endorse or promote
 *      products derived from this software without specific prior written
 *      permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* <<Header: /data/home/fredette/project/THE-WEIGHT-CVS/ndbootd/config/ndbootd-bpf.c,v 1.4 2001/05/23 02:35:49 fredette Exp >> */

/*
 * <<Log: ndbootd-bpf.c,v >>
 * Revision 1.4  2001/05/23 02:35:49  fredette
 * Changed many debugging printfs to compile quietly on the
 * alpha.  Patch from Andrew Brown <atatat@atatdot.net>.
 *
 * Revision 1.3  2001/05/22 13:13:24  fredette
 * Ran indent(1) with NetBSD's KNF-approximating profile.
 *
 * Revision 1.2  2001/05/09 20:50:46  fredette
 * Removed an unnecessary comment.
 *
 * Revision 1.1  2001/01/29 15:12:13  fredette
 * Added.
 *
 */

#include <sys/cdefs.h>
#if o
static const char _ndbootd_bpf_c_rcsid[] = "<<Id: ndbootd-bpf.c,v 1.4 2001/05/23 02:35:49 fredette Exp >>";
#else
__RCSID("$NetBSD: ndbootd-bpf.c,v 1.8 2004/12/01 23:18:20 christos Exp $");
#endif

/* includes: */
#include <sys/poll.h>
#include <net/bpf.h>
#include <paths.h>

/* structures: */
struct _ndbootd_interface_bpf {

        /* the size of the packet buffer for the interface: */
        size_t _ndbootd_interface_bpf_buffer_size;

        /* the packet buffer for the interface: */
        char *_ndbootd_interface_bpf_buffer;

        /* the next offset within the packet buffer, and the end of the data
         * in the packet buffer: */
        size_t _ndbootd_interface_bpf_buffer_offset;
        size_t _ndbootd_interface_bpf_buffer_end;
};

/* the BPF program to capture ND packets: */
static struct bpf_insn ndboot_bpf_filter[] = {

        /* drop this packet if its ethertype isn't ETHERTYPE_IP: */
        BPF_STMT(BPF_LD + BPF_H + BPF_ABS, NDBOOTD_OFFSETOF(struct ether_header, ether_type)),
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 9),

        /* drop this packet if its IP protocol isn't IPPROTO_ND: */
        BPF_STMT(BPF_LD + BPF_B + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_p)),
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_ND, 0, 7),

        /* drop this packet if it's a fragment: */
        BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_off)),
        BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x3fff, 5, 0),

        /* drop this packet if it is carrying data (we only want requests,
         * which have no data): */
        BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_len)),
        BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, sizeof(struct ether_header)),
        BPF_STMT(BPF_ALU + BPF_SUB + BPF_X, 0),
        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ndboot_packet), 0, 1),

        /* accept this packet: */
        BPF_STMT(BPF_RET + BPF_K, (u_int) -1),

        /* drop this packet: */
        BPF_STMT(BPF_RET + BPF_K, 0),
};

/* this opens a raw socket using BPF. */
int
ndbootd_raw_open(struct ndbootd_interface * interface)
{
        int network_fd;
        int saved_errno;
        u_int bufsize;
        u_int bpf_opt;
        struct bpf_version version;
        u_int packet_buffer_size;
        struct bpf_program program;
        struct _ndbootd_interface_bpf *interface_bpf;
        const char *dev_bpf_filename = _PATH_BPF;

        /* loop trying to open the /dev/bpf device: */
        if ((network_fd = open(dev_bpf_filename, O_RDWR)) < 0) {
                /* we have failed: */
                _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno)));
                return (-1);
        }
        _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename));

        /* this macro helps in closing the BPF socket on error: */
#define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno

        /* check the BPF version: */
        if (ioctl(network_fd, BIOCVERSION, &version) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s",
                        dev_bpf_filename, strerror(errno)));
                _NDBOOTD_RAW_OPEN_ERROR(close(network_fd));
                return (-1);
        }
        if (version.bv_major != BPF_MAJOR_VERSION
            || version.bv_minor < BPF_MINOR_VERSION) {
                _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d",
                        version.bv_major, version.bv_minor,
                        BPF_MAJOR_VERSION, BPF_MINOR_VERSION));
                close(network_fd);
                errno = ENXIO;
                return (-1);
        }
        /* put the BPF device into immediate mode: */
        bpf_opt = TRUE;
        if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s",
                        dev_bpf_filename, strerror(errno)));
                _NDBOOTD_RAW_OPEN_ERROR(close(network_fd));
                return (-1);
        }
        /* set a reasonable sized buffer for the BPF device */
        bufsize = 32768;
        if (ioctl(network_fd, BIOCSBLEN, &bufsize) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed set buffer size to %d: %s",
                        bufsize, strerror(errno)));
        }
        /* tell the BPF device we're providing complete Ethernet headers: */
        bpf_opt = TRUE;
        if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s",
                        dev_bpf_filename, strerror(errno)));
                _NDBOOTD_RAW_OPEN_ERROR(close(network_fd));
                return (-1);
        }
        /* point the BPF device at the interface we're using: */
        if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s",
                        interface->ndbootd_interface_ifreq->ifr_name, strerror(errno)));
                saved_errno = errno;
                close(network_fd);
                errno = saved_errno;
                return (-1);
        }
        /* set the filter on the BPF device: */
        program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]);
        program.bf_insns = ndboot_bpf_filter;
        if (ioctl(network_fd, BIOCSETF, &program) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s",
                        dev_bpf_filename, strerror(errno)));
                _NDBOOTD_RAW_OPEN_ERROR(close(network_fd));
                return (-1);
        }
        /* get the BPF read buffer size: */
        if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) {
                _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s",
                        dev_bpf_filename, strerror(errno)));
                _NDBOOTD_RAW_OPEN_ERROR(close(network_fd));
                return (-1);
        }
        _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u",
                dev_bpf_filename, packet_buffer_size));

        /* allocate our private interface information and we're done: */
        interface->ndbootd_interface_fd = network_fd;
        interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1);
        interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size;
        interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size);
        interface->_ndbootd_interface_raw_private = interface_bpf;
        return (0);
#undef _NDBOOTD_RAW_OPEN_ERROR
}

/* this reads a raw packet: */
int
ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size)
{
        struct _ndbootd_interface_bpf *interface_bpf;
        ssize_t buffer_end;
        struct bpf_hdr the_bpf_header;
        struct pollfd set[1];

        /* recover our state: */
        interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private;

        /* loop until we have something to return: */
        set[0].fd = interface->ndbootd_interface_fd;
        set[0].events = POLLIN;
        for (;;) {

                /* if the buffer is empty, fill it: */
                if (interface_bpf->_ndbootd_interface_bpf_buffer_offset
                    >= interface_bpf->_ndbootd_interface_bpf_buffer_end) {

                        /* poll on the BPF socket: */
                        _NDBOOTD_DEBUG((fp, "bpf: calling poll"));
                        switch (poll(set, 1, INFTIM)) {
                        case 0:
                                _NDBOOTD_DEBUG((fp, "bpf: poll returned zero"));
                                continue;
                        case 1:
                                break;
                        default:
                                if (errno == EINTR) {
                                        _NDBOOTD_DEBUG((fp, "bpf: poll got EINTR"));
                                        continue;
                                }
                                _NDBOOTD_DEBUG((fp, "bpf: poll failed: %s", strerror(errno)));
                                return (-1);
                        }
                        assert(set[0].revents & POLLIN);

                        /* read the BPF socket: */
                        _NDBOOTD_DEBUG((fp, "bpf: calling read"));
                        buffer_end = read(interface->ndbootd_interface_fd,
                            interface_bpf->_ndbootd_interface_bpf_buffer,
                            interface_bpf->_ndbootd_interface_bpf_buffer_size);
                        if (buffer_end <= 0) {
                                _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno)));
                                return (-1);
                        }
                        _NDBOOTD_DEBUG((fp, "bpf: read %ld bytes of packets", (long) buffer_end));
                        interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0;
                        interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end;
                }
                /* if there's not enough for a BPF header, flush the buffer: */
                if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset
                        + sizeof(the_bpf_header))
                    > interface_bpf->_ndbootd_interface_bpf_buffer_end) {
                        _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes"));
                        interface_bpf->_ndbootd_interface_bpf_buffer_end = 0;
                        continue;
                }
                /* get the BPF header and check it: */
                memcpy(&the_bpf_header,
                    interface_bpf->_ndbootd_interface_bpf_buffer
                    + interface_bpf->_ndbootd_interface_bpf_buffer_offset,
                    sizeof(the_bpf_header));
                interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen;

                /* if we're missing some part of the packet: */
                if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen
                    || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen)
                        > interface_bpf->_ndbootd_interface_bpf_buffer_end)) {
                        _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet"));
                        interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen;
                        continue;
                }
                /* silently ignore packets that don't even have Ethernet
                 * headers, and those packets that we transmitted: */
                if (the_bpf_header.bh_datalen < sizeof(struct ether_header)
                    || !memcmp(((struct ether_header *)
                            (interface_bpf->_ndbootd_interface_bpf_buffer
                                + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost,
                        interface->ndbootd_interface_ether,
                        ETHER_ADDR_LEN)) {
                        /* silently ignore packets from us: */
                        interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen;
                        continue;
                }
                /* if the caller hasn't provided a large enough buffer: */
                if (packet_buffer_size < the_bpf_header.bh_datalen) {
                        errno = EIO;
                        interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen;
                        return (-1);
                }
                /* return this captured packet to the user: */
                memcpy(packet_buffer,
                    interface_bpf->_ndbootd_interface_bpf_buffer
                    + interface_bpf->_ndbootd_interface_bpf_buffer_offset,
                    the_bpf_header.bh_datalen);
                interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen;
                return (the_bpf_header.bh_datalen);
        }
        /* NOTREACHED */
}

/* this writes a raw packet: */
int
ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size)
{
        return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size));
}