/*************************************************************************
 * (C) 2011 AITNET - Sofia/Bulgaria - <office@aitnet.org>
 *  by Michael Pounov <misho@elwix.org>
 *
 * $Author: misho $
 * $Id: utils.c,v 1.5 2015/05/19 23:25:30 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"


void
Get1stEth(char *psDev, int devlen)
{
	struct ifaddrs *ifa;

	assert(psDev);
	assert(devlen > 0);

	getifaddrs(&ifa);
	strlcpy(psDev, ifa->ifa_name, devlen);
	freeifaddrs(ifa);
}

int
PrepareL2(const char *psDev, int *bpflen)
{
	int h, n = 1;
	register int i;
	char szStr[STRSIZ];
	struct ifreq ifr;
	struct bpf_program fcode = { 0 };
	struct bpf_insn insns[] = {
		BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
		BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ANSH_ID, 0, 1),
		BPF_STMT(BPF_RET + BPF_K, -1),
		BPF_STMT(BPF_RET + BPF_K, 0),
	};

	FTRACE(3);
	assert(psDev);

	fcode.bf_len = sizeof(insns) / sizeof(struct bpf_insn);
	fcode.bf_insns = insns;

	for (i = 0; i < 10; i++) {
		memset(szStr, 0, sizeof szStr);
		snprintf(szStr, sizeof szStr, "/dev/bpf%d", i);
		h = open(szStr, O_RDWR);
		if (h > 2)
			break;
	}
	if (h < 3) {
		printf("Error:: open bpf %s #%d - %s\n", szStr, errno, strerror(errno));
		return -1;
	}

	if (ioctl(h, BIOCIMMEDIATE, &n) == -1) {
		printf("Error:: set interface %s to bpf #%d - %s\n", psDev, errno, strerror(errno));
		close(h);
		return -1;
	}
	n = USHRT_MAX + 1;
	if (ioctl(h, BIOCSBLEN, &n) == -1) {
		printf("Error:: set buffer interface %s buffer length #%d - %s\n", psDev, errno, strerror(errno));
		close(h);
		return -1;
	}
	strlcpy(ifr.ifr_name, psDev, sizeof ifr.ifr_name);
	if (ioctl(h, BIOCSETIF, &ifr) == -1) {
		printf("Error:: bind interface %s to bpf #%d - %s\n", psDev, errno, strerror(errno));
		close(h);
		return -1;
	}
	if (ioctl(h, BIOCSETF, &fcode) == -1) {
		printf("Error:: set filter interface %s to bpf #%d - %s\n", psDev, errno, strerror(errno));
		close(h);
		return -1;
	}
	if (ioctl(h, BIOCGBLEN, bpflen) == -1) {
		printf("Error:: get buffer interface %s buffer length #%d - %s\n", psDev, errno, strerror(errno));
		close(h);
		return -1;
	}

	n = fcntl(h, F_GETFL);
	fcntl(h, F_SETFL, n | O_NONBLOCK);

	VERB(3) LOG("Openned device handle %d with bpf buflen %d", h, *bpflen);
	return h;
}

int
PrepareL3(const sockaddr_t *sa, int *bpflen)
{
	int h, n = 1;

	FTRACE(3);
	assert(sa);

	h = socket(sa->sa.sa_family ? sa->sa.sa_family : AF_INET, SOCK_RAW, IPPROTO_ICMP);
	if (h == -1) {
		printf("Error:: Cant open raw socket #%d - %s\n", errno, strerror(errno));
		return -1;
	}
	/*
	if (setsockopt(h, SOL_SOCKET, SO_REUSEADDR, &n, sizeof n) == -1) {
		printf("Error:: Cant set raw socket #%d - %s\n", errno, strerror(errno));
		close(h);
		return -1;
	}
	*/
	if (sa->sa.sa_family && bind(h, &sa->sa, sa->sa.sa_len) == -1) {
		printf("Error:: Cant bind to raw socket #%d - %s\n", errno, strerror(errno));
		close(h);
		return -1;
	}

	n = fcntl(h, F_GETFL);
	fcntl(h, F_SETFL, n | O_NONBLOCK);

	*bpflen = USHRT_MAX;
	VERB(3) LOG("Openned socket handle %d", h);
	return h;
}

char
icmpRecv(int s, u_int * __restrict seq, u_short * __restrict id, u_int * __restrict crypted, 
		u_char * __restrict data, int * __restrict datlen, sockaddr_t *sa, socklen_t *salen)
{
	int ret = 0;
	struct icmp *icmp;
	struct ansh_hdr *hdr;
	u_char buf[USHRT_MAX] = { 0 };
	u_int crc;

	ret = recvfrom(s, buf, sizeof buf, 0, &sa->sa, salen);
	if (ret == -1) {
		ERR("Receive recvfrom() #%d - %s", errno, strerror(errno));
		return ANSH_FLG_ERR;
	} else
		VERB(4) LOG("Get packet with len=%d", ret);

	/* check header len */
	if (ret < (sizeof(struct ip) + sizeof(struct icmp) + sizeof(struct ansh_hdr))) {
		VERB(1) LOG("Discard packet too short %d ...", ret);
		return ANSH_FLG_ERR;
	} else
		icmp = (struct icmp*) (buf + sizeof(struct ip));

	/* check echo magic ansh code */
	if (icmp->icmp_type != ICMP_ECHOREPLY || icmp->icmp_code != ANSH_CODE) {
		VERB(3) LOG("Packet isnt for me %d ... icmp_code=%d", ret, icmp->icmp_code);
		return ANSH_FLG_ERR;
	} else
		hdr = (struct ansh_hdr*) (buf + sizeof(struct ip) + sizeof(struct icmp));

	/* check version and total size of packet */
	if (hdr->ansh_ver != ANSH_VERSION) {
		VERB(3) LOG("Packet with wrong version ...");
		return ANSH_FLG_ERR;
	}
	if (crypted) {
		if (hdr->ansh_nonce && !*crypted) {
			VERB(3) LOG("Channel INSECURED:: Crypted communication not supported at this moment ...");
			return ANSH_FLG_ERR;
		}
		if (!hdr->ansh_nonce && *crypted) {
			VERB(3) LOG("Channel SECURED:: Plain text communication not supported at this moment ...");
			return ANSH_FLG_ERR;
		}
		if (ntohl(hdr->ansh_nonce) != *crypted)
			VERB(4) LOG("Detect change of nonce from %x to %x", *crypted, ntohl(hdr->ansh_nonce));

		*crypted = ntohl(hdr->ansh_nonce);
	}

	/* check crc of packet */
	crc = hdr->ansh_crc;
	hdr->ansh_crc ^= hdr->ansh_crc;
	hdr->ansh_crc = htonl(crcAdler((u_char*) hdr, ntohs(hdr->ansh_len)));
	if (crc != hdr->ansh_crc) {
		VERB(3) LOG("Packet with wrong crc ...");
		return ANSH_FLG_ERR;
	}

	/* copy data */
	if (data && datlen) {
		memset(data, 0, *datlen);
		*datlen = ntohs(hdr->ansh_len) - sizeof(struct ansh_hdr);
		memcpy(data, buf + sizeof(struct ip) + sizeof(struct icmp) + sizeof(struct ansh_hdr), *datlen);
	}

	if (seq)
		*seq = ntohl(hdr->ansh_seq);
	if (id)
		*id = ntohs(icmp->icmp_id);
	return hdr->ansh_flg;
}

int
icmpSend(int s, u_int seq, u_short id, char flg, u_int crypted, u_char *data, int datlen, 
		sockaddr_t *sa, socklen_t salen)
{
	u_char *pos, buf[USHRT_MAX] = { 0 };
	struct icmp *icmp;
	struct ansh_hdr *hdr;
	int ret = 0;

	assert(data);
	if ((sizeof buf - sizeof(struct icmp) + sizeof(struct ansh_hdr)) < datlen)
		return ANSH_FLG_ERR;

	icmp = (struct icmp*) buf;
	hdr = (struct ansh_hdr*) (buf + sizeof(struct icmp));
	pos = buf + sizeof(struct icmp) + sizeof(struct ansh_hdr);

	memcpy(pos, data, datlen);

	hdr->ansh_ver = ANSH_VERSION;
	hdr->ansh_flg = flg;
	hdr->ansh_len = htons(datlen + sizeof(struct ansh_hdr));
	hdr->ansh_nonce = htonl(crypted);
	hdr->ansh_seq = htonl(seq);
	hdr->ansh_crc = 0;
	hdr->ansh_crc = htonl(crcAdler((u_char*) hdr, ntohs(hdr->ansh_len)));

	icmp->icmp_type = ICMP_ECHOREPLY;
	icmp->icmp_code = ANSH_CODE;
	icmp->icmp_id = htons(id);
	icmp->icmp_seq = htons(datlen);
	icmp->icmp_cksum = 0;
	icmp->icmp_cksum = crcIP(buf, sizeof(struct icmp) + sizeof(struct ansh_hdr) + datlen);

	if ((ret = sendto(s, buf, sizeof(struct icmp) + sizeof(struct ansh_hdr) + datlen, 
					0, &sa->sa, salen)) == -1) {
		ERR("Send sendto() #%d - %s", errno, strerror(errno));
		return ANSH_FLG_ERR;
	} else
		VERB(4) LOG("Put packet with len=%d", ret);
	if (ret != sizeof(struct icmp) + sizeof(struct ansh_hdr) + datlen) {
		VERB(3) LOG("Sended data %d is different from source data len %d", ret, 
				(int) (sizeof(struct icmp) + sizeof(struct ansh_hdr) + datlen));
		return ANSH_FLG_ERR;
	}

	return ret;
}

static int
_pkt_Send(int s, u_int seq, char flg, u_int crypted, u_char *data, int datlen, ether_addr_t *ea)
{
	u_char *pos, *str, buf[USHRT_MAX] = { 0 };
	struct ether_header *e = (struct ether_header*) buf;
	struct ansh_hdr *hdr;
	int ret = 0;

	assert(data);
	if ((sizeof buf - ETHER_HDR_LEN + sizeof(struct ansh_hdr)) < datlen)
		return ANSH_FLG_ERR;

	e->ether_type = ntohs(ANSH_ID);
	memcpy(e->ether_dhost, ea->octet, ETHER_ADDR_LEN);
	hdr = (struct ansh_hdr*) (buf + ETHER_HDR_LEN);
	pos = ((u_char*) hdr) + sizeof(struct ansh_hdr);

	memcpy(pos, data, datlen);

	if (Crypted) {
		str = cryptBuffer(pos, datlen, Crypted);
		if (str) {
			memcpy(pos, str, datlen);
			e_free(str);
		}
	}

	hdr->ansh_ver = ANSH_VERSION;
	hdr->ansh_flg = flg;
	hdr->ansh_len = htons(datlen + sizeof(struct ansh_hdr));
	hdr->ansh_nonce = htonl(crypted);
	hdr->ansh_seq = htonl(seq);
	hdr->ansh_crc = 0;
	hdr->ansh_crc = htonl(crcAdler((u_char*) hdr, ntohs(hdr->ansh_len)));

	if ((ret = write(s, buf, ETHER_HDR_LEN + sizeof(struct ansh_hdr) + datlen)) == -1) {
		ERR("Send packet() #%d - %s", errno, strerror(errno));
		return ANSH_FLG_ERR;
	} else
		VERB(4) LOG("Put packet with len=%d", ret);
	if (ret != ETHER_HDR_LEN + sizeof(struct ansh_hdr) + datlen) {
		VERB(3) LOG("Sended data %d is different from source data len %d", ret, 
				(int) (ETHER_HDR_LEN + sizeof(struct ansh_hdr) + datlen));
		return ANSH_FLG_ERR;
	}

	return ret;
}

int
pktSend(int s, u_int seq, char flg, u_int crypted, u_char *data, int datlen, struct e_ether_addr *ea)
{
	int wlen, ret = 0;
	u_char *pos = data;

	while (datlen > -1) {
		wlen = _pkt_Send(s, seq, flg, crypted, pos, (datlen > 512) ? 512 : datlen, ea);
		if (wlen == -1)
			return -1;
		else {
			pos += wlen;
			datlen -= wlen;
			ret += wlen;
		}
	}

	return ret;
}

static char
_pkt_Recv(u_char * __restrict buf, int rlen, u_int * __restrict seq, u_int * __restrict crypted, 
		u_char * __restrict data, int * __restrict datlen, 
		u_char ** __restrict next, int * __restrict nextlen)
{
	int bias;
	struct bpf_hdr *bpf;
	struct ansh_hdr *hdr;
	u_int crc;
	u_char *str;

	if (rlen < (sizeof(struct bpf_hdr) + ETHER_HDR_LEN + sizeof(struct ansh_hdr))) {
		VERB(1) LOG("Discard packet too short %d ...", rlen);
		return ANSH_FLG_ERR;
	} else {
		bpf = (struct bpf_hdr*) buf;
		hdr = (struct ansh_hdr*) (buf + bpf->bh_hdrlen + ETHER_HDR_LEN);
	}

	/* slice readed data to packets */
	if ((bias = BPF_WORDALIGN(bpf->bh_hdrlen + bpf->bh_caplen)) < rlen) {
		*next = buf + bias;
		*nextlen = rlen - bias;
	} else {
		*next = NULL;
		*nextlen = 0;
	}

	/* check version and total size of packet */
	if (hdr->ansh_ver != ANSH_VERSION) {
		VERB(3) LOG("Packet with wrong version ... %d", hdr->ansh_ver);
		return ANSH_FLG_ERR;
	}
	if (crypted) {
		if (hdr->ansh_nonce && !*crypted) {
			VERB(3) LOG("Channel INSECURED:: Crypted communication not supported at this moment ...");
			return ANSH_FLG_ERR;
		}
		if (!hdr->ansh_nonce && *crypted) {
			VERB(3) LOG("Channel SECURED:: Plain text communication not supported at this moment ...");
			return ANSH_FLG_ERR;
		}
		if (ntohl(hdr->ansh_nonce) != *crypted)
			VERB(4) LOG("Detect change of nonce from %x to %x", *crypted, ntohl(hdr->ansh_nonce));

		*crypted = ntohl(hdr->ansh_nonce);
	}

	/* check crc of packet */
	crc = hdr->ansh_crc;
	hdr->ansh_crc ^= hdr->ansh_crc;
	hdr->ansh_crc = htonl(crcAdler((u_char*) hdr, ntohs(hdr->ansh_len)));
	if (crc != hdr->ansh_crc) {
		VERB(3) LOG("Packet with wrong crc ...");
		return ANSH_FLG_ERR;
	}

	/* select data */
	if (data) {
		*datlen = ntohs(hdr->ansh_len) - sizeof(struct ansh_hdr);
		if (Crypted) {
			str = cryptBuffer(buf + bpf->bh_hdrlen + ETHER_HDR_LEN + sizeof(struct ansh_hdr), 
					*datlen, Crypted);
			if (str) {
				memcpy(buf + bpf->bh_hdrlen + ETHER_HDR_LEN + sizeof(struct ansh_hdr), 
						str, *datlen);
				e_free(str);
			}
		}

		memcpy(data, buf + bpf->bh_hdrlen + ETHER_HDR_LEN + sizeof(struct ansh_hdr), *datlen);
	}

	if (seq)
		*seq = ntohl(hdr->ansh_seq);
	return hdr->ansh_flg;
}

char
pktRecv(int s, u_int * __restrict seq, u_int * __restrict crypted, u_char * __restrict data, 
		int * __restrict datlen, struct ether_header *eth)
{
	u_char *buf, *next, *ptr, *pos = data;
	int nextlen, rlen, buflen, ptrlen;
	char flg;
	struct bpf_hdr *bpf;
	struct ether_header *e;

	if (!eth || !data || !datlen)
		return ANSH_FLG_ERR;
	else
		memset(data, 0, *datlen);

	if (!(buf = e_malloc(*datlen))) {
		ERR("malloc() #%d - %s", errno, strerror(errno));
		return ANSH_FLG_ERR;
	}

	rlen = read(s, buf, *datlen);
	if (rlen == -1) {
		ERR("Receive packet() #%d - %s", errno, strerror(errno));
		e_free(buf);
		return ANSH_FLG_ERR;
	} else
		VERB(4) LOG("Get packet with len=%d", rlen);

	/* check header len */
	if (rlen < (sizeof(struct bpf_hdr) + ETHER_HDR_LEN + sizeof(struct ansh_hdr))) {
		VERB(1) LOG("Discard packet too short %d ...", rlen);
		e_free(buf);
		return ANSH_FLG_ERR;
	} else {
		bpf = (struct bpf_hdr*) buf;
		e = (struct ether_header*) (buf + bpf->bh_hdrlen);
		memcpy(eth, e, ETHER_HDR_LEN);
	}

	ptr = next = buf;
	ptrlen = nextlen = rlen;
	if ((flg = _pkt_Recv(ptr, ptrlen, seq, crypted, pos, &buflen, &next, &nextlen)) == -1) {
		e_free(buf);
		return ANSH_FLG_ERR;
	} else {
		pos += buflen;
		*datlen = buflen;
		ptr = next;
		ptrlen = nextlen;
	}
	/* get additional packets from buffer */
	while (next && nextlen > 0)
		if (_pkt_Recv(ptr, ptrlen, seq, crypted, pos, &buflen, &next, &nextlen) == -1)
			break;
		else {
			pos += buflen;
			*datlen += buflen;
			ptr = next;
			ptrlen = nextlen;
		}

	e_free(buf);

	return flg;
}

void *
TOfunc(sched_task_t *task)
{
	struct tagProc *proc;

	FTRACE(3);

	/* not found argument, drop data */
	if (!(proc = TASK_ARG(task)))
		return (void*) -1;

	if (proc->proc_pid)
		kill(proc->proc_pid, SIGTERM);

	return NULL;
}

u_char *
cryptBuffer(u_char *buf, int rlen, u_int ctr)
{
	u_char *str, ivec[AES_BLOCK_SIZE] = { 0 };
	u_int rctr = htonl(ctr);

	FTRACE(3);

	if (!buf)
		return NULL;

	memcpy(ivec, &ctr, sizeof ctr);
	memcpy(ivec + 4, &rctr, sizeof rctr);
	memcpy(ivec + 8, &ctr, sizeof ctr);
	memcpy(ivec + 12, &rctr, sizeof rctr);

	if (io_ctr_AES(buf, rlen, &str, (u_char*) Key, ivec) == -1)
		return NULL;

	return str;
}