/*
 * veth.c	       "ethernet tunnel"
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Authors:	Pavel Emelianov, <xemul@openvz.org>
 *
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/genetlink.h>

#include "utils.h"
#include "veth.h"

#define GENLMSG_DATA(glh)       ((void *)(NLMSG_DATA(glh) + GENL_HDRLEN))
#define NLA_DATA(na)            ((void *)((char*)(na) + NLA_HDRLEN))

static int do_veth_help(void)
{
	fprintf(stderr, "Usage: ip veth add DEVICE PEER_NAME\n");
	fprintf(stderr, "               del DEVICE\n");
	exit(-1);
}

static int genl_ctrl_resolve_family(const char *family)
{
	struct rtnl_handle rth;
	struct nlmsghdr *nlh;
	struct genlmsghdr *ghdr;
	int ret = 0;
	struct {
		struct nlmsghdr         n;
		char                    buf[4096];
	} req;

	memset(&req, 0, sizeof(req));

	nlh = &req.n;
	nlh->nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	nlh->nlmsg_type = GENL_ID_CTRL;

	ghdr = NLMSG_DATA(&req.n);
	ghdr->cmd = CTRL_CMD_GETFAMILY;

	if (rtnl_open_byproto(&rth, 0, NETLINK_GENERIC) < 0) {
		fprintf(stderr, "Cannot open generic netlink socket\n");
		exit(1);
	}

	addattr_l(nlh, 128, CTRL_ATTR_FAMILY_NAME, family, strlen(family) + 1);

	if (rtnl_talk(&rth, nlh, 0, 0, nlh, NULL, NULL) < 0) {
		fprintf(stderr, "Error talking to the kernel\n");
		goto errout;
	}

	{
		struct rtattr *tb[CTRL_ATTR_MAX + 1];
		struct genlmsghdr *ghdr = NLMSG_DATA(nlh);
		int len = nlh->nlmsg_len;
		struct rtattr *attrs;

		if (nlh->nlmsg_type !=  GENL_ID_CTRL) {
			fprintf(stderr, "Not a controller message, nlmsg_len=%d "
				"nlmsg_type=0x%x\n", nlh->nlmsg_len, nlh->nlmsg_type);
			goto errout;
		}

		if (ghdr->cmd != CTRL_CMD_NEWFAMILY) {
			fprintf(stderr, "Unkown controller command %d\n", ghdr->cmd);
			goto errout;
		}

		len -= NLMSG_LENGTH(GENL_HDRLEN);

		if (len < 0) {
			fprintf(stderr, "wrong controller message len %d\n", len);
			return -1;
		}

		attrs = (struct rtattr *) ((char *) ghdr + GENL_HDRLEN);
		parse_rtattr(tb, CTRL_ATTR_MAX, attrs, len);

		if (tb[CTRL_ATTR_FAMILY_ID] == NULL) {
			fprintf(stderr, "Missing family id TLV\n");
			goto errout;
		}

		ret = *(__u16 *) RTA_DATA(tb[CTRL_ATTR_FAMILY_ID]);
	}

errout:
	rtnl_close(&rth);
	return ret;
}

static int do_veth_operate(char *dev, char *peer, int cmd)
{
	struct rtnl_handle rth;
	struct nlmsghdr *nlh;
	struct genlmsghdr *ghdr;
	struct nlattr *attr;
	struct  {
		struct nlmsghdr n;
		struct genlmsghdr h;
		char bug[1024];
	} req;
	int family, len;
	int err = 0;

	family = genl_ctrl_resolve_family("veth");
	if (family == 0) {
		fprintf(stderr, "veth: Can't resolve family\n");
		exit(1);
	}

	if (rtnl_open_byproto(&rth, 0, NETLINK_GENERIC) < 0)
		exit(1);

	nlh = &req.n;
	nlh->nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
	nlh->nlmsg_flags = NLM_F_REQUEST;
	nlh->nlmsg_type = family;
	nlh->nlmsg_seq = 0;

	ghdr = &req.h;
	ghdr->cmd = cmd;

	attr = (struct nlattr *) GENLMSG_DATA(&req);
	len = strlen(dev);
	attr->nla_type = VETH_ATTR_DEVNAME;
	attr->nla_len = len + 1 + NLA_HDRLEN;
	memcpy(NLA_DATA(attr), dev, len);
	nlh->nlmsg_len += NLMSG_ALIGN(attr->nla_len);

	if (peer) {
		attr = (struct nlattr *)((char *)attr +
				NLMSG_ALIGN(attr->nla_len));
		len = strlen(peer);
		attr->nla_type = VETH_ATTR_PEERNAME;
		attr->nla_len = len + 1 + NLA_HDRLEN;
		memcpy(NLA_DATA(attr), peer, len);
		nlh->nlmsg_len += NLMSG_ALIGN(attr->nla_len);
	}

	if (rtnl_send(&rth, (char *) &req, nlh->nlmsg_len) < 0) {
		err = -1;
		fprintf(stderr, "Error talking to the kernel (add)\n");
	}

	rtnl_close(&rth);
	return err;
}

static int do_veth_add(int argc, char **argv)
{
	if (argc < 2)
		return do_veth_help();

	return do_veth_operate(argv[0], argv[1], VETH_CMD_ADD);
}

static int do_veth_del(int argc, char **argv)
{
	char *name;

	if (argc < 1)
		return do_veth_help();

	return do_veth_operate(argv[0], NULL, VETH_CMD_DEL);
}

int do_veth(int argc, char **argv)
{
	if (argc == 0)
		return do_veth_help();

	if (strcmp(*argv, "add") == 0 || strcmp(*argv, "a") == 0)
		return do_veth_add(argc - 1, argv + 1);
	if (strcmp(*argv, "del") == 0 || strcmp(*argv, "d") == 0)
		return do_veth_del(argc - 1, argv + 1);
	if (strcmp(*argv, "help") == 0)
		return do_veth_help();

	fprintf(stderr, "Command \"%s\" is unknown, try \"ip veth help\".\n", *argv);
	exit(-1);
}