/*************************************************************************
* (C) 2013 AITNET ltd - Sofia/Bulgaria - <misho@aitnet.org>
*  by Michael Pounov <misho@elwix.org>
*
* $Author: misho $
* $Id: bpf.c,v 1.3 2013/07/09 00:35:36 misho Exp $
*
**************************************************************************
The ELWIX and AITNET software is distributed under the following
terms:

All of the documentation and software included in the ELWIX and AITNET
Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>

Copyright 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
	by Michael Pounov <misho@elwix.org>.  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 Michael Pounov <misho@elwix.org>
ELWIX - Embedded LightWeight unIX and its contributors.
4. Neither the name of AITNET 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 AITNET 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 REGENTS 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.
*/
#include "global.h"


/*
 * io_get1stiface() - Get first interface of host
 *
 * @szIface = interface string buffer
 * @iflen = size of interface buffer
 * return: -1 error or 0 ok
 */
int
io_get1stiface(char *szIface, int iflen)
{
	struct ifaddrs *ifa;

	if (!szIface || !iflen)
		return -1;

	getifaddrs(&ifa);
	strlcpy(szIface, ifa->ifa_name, iflen);
	freeifaddrs(ifa);
	return 0;
}

/*
 * io_etherClose() - Close BPF interface
 *
 * @eth = bpf handle
 * @zcbuf = zero copy buffer, if BPF supports it and isn't NULL
 * return: none
 */
void
io_etherClose(int eth, void **zcbuf)
{
#ifdef __FreeBSD__
	struct bpf_zbuf *zbuf = NULL;
#endif

	if (eth > STDERR_FILENO)
		close(eth);

	if (zcbuf && *zcbuf) {
#ifdef __FreeBSD__
		zbuf = *zcbuf;
		munmap(zbuf->bz_bufb, zbuf->bz_buflen);
		munmap(zbuf->bz_bufa, zbuf->bz_buflen);
		e_free(*zcbuf);
		*zcbuf = NULL;
#endif
	}
}

#ifdef __FreeBSD__
static inline struct bpf_zbuf *
allocZCbuf(u_int len)
{
	struct bpf_zbuf *zbuf = NULL;

	zbuf = e_malloc(sizeof(struct bpf_zbuf));
	if (!zbuf) {
		io_SetErr(elwix_GetErrno(), "%s", elwix_GetError());
		return NULL;
	} else
		memset(zbuf, 0, sizeof(struct bpf_zbuf));

	zbuf->bz_buflen = roundup(len, getpagesize());
	zbuf->bz_bufa = mmap(NULL, zbuf->bz_buflen, PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
	if (zbuf->bz_bufa == MAP_FAILED) {
		LOGERR;
		e_free(zbuf);
		return NULL;
	} else
		memset(zbuf->bz_bufa, 0, zbuf->bz_buflen);
	zbuf->bz_bufb = mmap(NULL, zbuf->bz_buflen, PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
	if (zbuf->bz_bufb == MAP_FAILED) {
		LOGERR;
		munmap(zbuf->bz_bufa, zbuf->bz_buflen);
		e_free(zbuf);
		return NULL;
	} else
		memset(zbuf->bz_bufb, 0, zbuf->bz_buflen);

	return zbuf;
}
#endif

/*
 * io_etherOpen() - Open BPF interface to device
 *
 * @csIface = interface name
 * @flags = open flags
 * @whdr = with complete headers
 * @wdlt = with data link type
 * @buflen = buffer length
 * @zcbuf = zero copy buffer, if BPF supports it and isn't NULL
 * return: -1 error or >-1 bpf handle
 */
int
io_etherOpen(const char *csIface, int flags, int whdr, int wdlt, 
		u_int *buflen, void **zcbuf)
{
	int eth = -1;
	register int i;
	char szStr[STRSIZ];
	struct ifreq ifr;
	u_int n = 1;

#ifndef __FreeBSD__
	if (zcbuf) {
		io_SetErr(ENOTSUP, "bpf zero copy buffer mode is not supported");
		return -1;
	}
#endif

	for (i = 0; i < BPF_DEV_MAX; i++) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "/dev/bpf%d", i);
		eth = open(szStr, flags);
		if (eth > STDERR_FILENO)
			break;
	}
	if (eth < 3) {
		LOGERR;
		return -1;
	}

	if (!zcbuf) {
		if (ioctl(eth, BIOCGBLEN, &n) == -1) {
			LOGERR;
			close(eth);
			return -1;
		} else
			n = (buflen && *buflen) ? *buflen : n;
		if (ioctl(eth, BIOCSBLEN, &n) == -1) {
			LOGERR;
			close(eth);
			return -1;
		}
		if (buflen && *buflen)
			*buflen = n;
	} else {
#ifdef __FreeBSD__
		n = BPF_BUFMODE_ZBUF;
		if (ioctl(eth, BIOCSETBUFMODE, &n) == -1) {
			LOGERR;
			close(eth);
			return -1;
		}
		if (ioctl(eth, BIOCGETZMAX, &n) == -1) {
			LOGERR;
			close(eth);
			return -1;
		} else
			n = (buflen && *buflen) ? *buflen : n;
		if (!(*zcbuf = allocZCbuf(n))) {
			close(eth);
			return -1;
		}
		if (ioctl(eth, BIOCSETZBUF, *zcbuf) == -1) {
			LOGERR;
			io_etherClose(eth, zcbuf);
			return -1;
		}
		if (buflen && *buflen)
			*buflen = n;
#endif
	}

	if (csIface)
		strlcpy(szStr, csIface, sizeof szStr);
	else if (io_get1stiface(szStr, sizeof szStr) == -1) {
		io_etherClose(eth, zcbuf);
		return -1;
	}
	memset(&ifr, 0, sizeof ifr);
	strlcpy(ifr.ifr_name, szStr, sizeof ifr.ifr_name);
	if (ioctl(eth, BIOCSETIF, &ifr) == -1) {
		LOGERR;
		io_etherClose(eth, zcbuf);
		return -1;
	}

	n = 1;
	if (whdr && ioctl(eth, BIOCSHDRCMPLT, &n) == -1) {
		LOGERR;
		io_etherClose(eth, zcbuf);
		return -1;
	}
	if (wdlt && ioctl(eth, BIOCSDLT, &wdlt) == -1) {
		LOGERR;
		io_etherClose(eth, zcbuf);
		return -1;
	}
	if (ioctl(eth, BIOCIMMEDIATE, &n) == -1) {
		LOGERR;
		io_etherClose(eth, zcbuf);
		return -1;
	}

	return eth;
}

/*
 * io_etherSend() - Send packet to bpf
 *
 * @eth = bpf handle
 * @buf = buffer
 * @buflen = buffer length
 * return: -1 error or !=-1 written bytes
 */
ssize_t
io_etherSend(int eth, const void *buf, size_t buflen)
{
	ssize_t wlen = 0;

	if (!buf || !buflen) {
		io_SetErr(EINVAL, "invalid arguments");
		return -1;
	}

	wlen = write(eth, buf, buflen);
	if (wlen == -1)
		LOGERR;
	return wlen;
}

#ifdef __FreeBSD__
static inline void
ackZCbuf(struct bpf_zbuf_header *bzh)
{
	atomic_store_rel_int(&bzh->bzh_user_gen, bzh->bzh_kernel_gen);
}

static inline int
chkZCbuf(struct bpf_zbuf_header *bzh)
{
	/* return true if userspace owns buffer, and false otherwise. */
	return (bzh->bzh_user_gen != atomic_load_acq_int(&bzh->bzh_kernel_gen));
}

static ssize_t
nextZCbuf(int eth, struct bpf_zbuf * __restrict zbuf, void * __restrict buf, size_t buflen)
{
	ssize_t rlen = 0;
	struct bpf_zbuf bz;
	struct bpf_zbuf_header *bzh;
	off_t pos = 0;

	bzh = (struct bpf_zbuf_header *) zbuf->bz_bufa;
	if (chkZCbuf(bzh)) {
		rlen = MIN(atomic_load_acq_int(&bzh->bzh_kernel_len), buflen);
		memcpy(buf + pos, zbuf->bz_bufa + sizeof(struct bpf_zbuf_header), rlen);
		ackZCbuf(bzh);
		pos += rlen;
	}
	bzh = (struct bpf_zbuf_header *) zbuf->bz_bufb;
	if (chkZCbuf(bzh)) {
		rlen = MIN(atomic_load_acq_int(&bzh->bzh_kernel_len), buflen);
		memcpy(buf + pos, zbuf->bz_bufb + sizeof(struct bpf_zbuf_header), rlen);
		ackZCbuf(bzh);
		pos += rlen;
	}

	if (!pos) {
		if ((rlen = ioctl(eth, BIOCROTZBUF, &bz)) == -1)
			LOGERR;
	} else
		rlen = pos;
	return rlen;
}
#endif

/*
 * io_etherRecv() - Receive packet from bpf
 *
 * @eth = bpf handle
 * @buf = buffer
 * @buflen = buffer length
 * @zcbuf = zero copy buffer, if BPF supports it and isn't NULL
 * return: -1 error or !=-1 readed bytes
 */
ssize_t
io_etherRecv(int eth, void * __restrict buf, size_t buflen, void * __restrict zcbuf)
{
	ssize_t rlen = 0;
	struct bpf_hdr *h;

	if (!buf || !buflen) {
		io_SetErr(EINVAL, "invalid arguments");
		return -1;
	}

	if (!zcbuf) {
		rlen = read(eth, buf, buflen);
		if (rlen == -1)
			LOGERR;
	} else {
#ifdef __FreeBSD__
		rlen = nextZCbuf(eth, (struct bpf_zbuf*) zcbuf, buf, buflen);
		if (!rlen)
			rlen = nextZCbuf(eth, (struct bpf_zbuf*) zcbuf, buf, buflen);
#else
		rlen = -1;
		io_SetErr(ENOTSUP, "bpf zero copy buffer mode is not supported");
#endif
	}

	h = (struct bpf_hdr*) buf;
	rlen -= h->bh_hdrlen;

	if (h->bh_caplen != rlen) {
		if (h->bh_caplen < rlen)
			rlen = h->bh_caplen;
		else {
			io_SetErr(EIO, "Captured %d bytes should be at most %d bytes", 
					h->bh_caplen, rlen);
			return -1;
		}
	}

	memmove(buf, buf + h->bh_hdrlen, rlen);
	return rlen;
}