ip/link_gre.c - maze/iproute2 - Git at Google

 /*
  * link_gre.c	gre driver module
  *
  *		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:	Herbert Xu <herbert@gondor.apana.org.au>
  *
  */

 #include <string.h>
 #include <net/if.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>

 #include <linux/ip.h>
 #include <linux/if_tunnel.h>
 #include "rt_names.h"
 #include "utils.h"
 #include "ip_common.h"
 #include "tunnel.h"

 static void usage(void) __attribute__((noreturn));
 static void usage(void)
 {
 	fprintf(stderr, "Usage: ip link { add | set | change | replace | del } NAME\n");
 	fprintf(stderr, "          type { gre | gretap } [ remote ADDR ] [ local ADDR ]\n");
 	fprintf(stderr, "          [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
 	fprintf(stderr, "          [ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ] [ dev PHYS_DEV ]\n");
 	fprintf(stderr, "\n");
 	fprintf(stderr, "Where: NAME := STRING\n");
 	fprintf(stderr, "       ADDR := { IP_ADDRESS | any }\n");
 	fprintf(stderr, "       TOS  := { NUMBER | inherit }\n");
 	fprintf(stderr, "       TTL  := { 1..255 | inherit }\n");
 	fprintf(stderr, "       KEY  := { DOTTED_QUAD | NUMBER }\n");
 	exit(-1);
 }

 static int gre_parse_opt(struct link_util *lu, int argc, char **argv,
 			 struct nlmsghdr *n)
 {
 	struct {
 		struct nlmsghdr n;
 		struct ifinfomsg i;
 		char buf[1024];
 	} req;
 	struct ifinfomsg *ifi = (struct ifinfomsg *)(n + 1);
 	struct rtattr *tb[IFLA_MAX + 1];
 	struct rtattr *linkinfo[IFLA_INFO_MAX+1];
 	struct rtattr *greinfo[IFLA_GRE_MAX + 1];
 	__u16 iflags = 0;
 	__u16 oflags = 0;
 	unsigned ikey = 0;
 	unsigned okey = 0;
 	unsigned saddr = 0;
 	unsigned daddr = 0;
 	unsigned link = 0;
 	__u8 pmtudisc = 1;
 	__u8 ttl = 0;
 	__u8 tos = 0;
 	int len;

 	if (!(n->nlmsg_flags & NLM_F_CREATE)) {
 		memset(&req, 0, sizeof(req));

 		req.n.nlmsg_len = NLMSG_LENGTH(sizeof(*ifi));
 		req.n.nlmsg_flags = NLM_F_REQUEST;
 		req.n.nlmsg_type = RTM_GETLINK;
 		req.i.ifi_family = preferred_family;
 		req.i.ifi_index = ifi->ifi_index;

 		if (rtnl_talk(&rth, &req.n, 0, 0, &req.n) < 0) {
 get_failed:
 			fprintf(stderr,
 				"Failed to get existing tunnel info.\n");
 			return -1;
 		}

 		len = req.n.nlmsg_len;
 		len -= NLMSG_LENGTH(sizeof(*ifi));
 		if (len < 0)
 			goto get_failed;

 		parse_rtattr(tb, IFLA_MAX, IFLA_RTA(&req.i), len);

 		if (!tb[IFLA_LINKINFO])
 			goto get_failed;

 		parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);

 		if (!linkinfo[IFLA_INFO_DATA])
 			goto get_failed;

 		parse_rtattr_nested(greinfo, IFLA_GRE_MAX,
 				    linkinfo[IFLA_INFO_DATA]);

 		if (greinfo[IFLA_GRE_IKEY])
 			ikey = rta_getattr_u32(greinfo[IFLA_GRE_IKEY]);

 		if (greinfo[IFLA_GRE_OKEY])
 			okey = rta_getattr_u32(greinfo[IFLA_GRE_OKEY]);

 		if (greinfo[IFLA_GRE_IFLAGS])
 			iflags = rta_getattr_u16(greinfo[IFLA_GRE_IFLAGS]);

 		if (greinfo[IFLA_GRE_OFLAGS])
 			oflags = rta_getattr_u16(greinfo[IFLA_GRE_OFLAGS]);

 		if (greinfo[IFLA_GRE_LOCAL])
 			saddr = rta_getattr_u32(greinfo[IFLA_GRE_LOCAL]);

 		if (greinfo[IFLA_GRE_REMOTE])
 			daddr = rta_getattr_u32(greinfo[IFLA_GRE_REMOTE]);

 		if (greinfo[IFLA_GRE_PMTUDISC])
 			pmtudisc = rta_getattr_u8(
 				greinfo[IFLA_GRE_PMTUDISC]);

 		if (greinfo[IFLA_GRE_TTL])
 			ttl = rta_getattr_u8(greinfo[IFLA_GRE_TTL]);

 		if (greinfo[IFLA_GRE_TOS])
 			tos = rta_getattr_u8(greinfo[IFLA_GRE_TOS]);

 		if (greinfo[IFLA_GRE_LINK])
 			link = rta_getattr_u8(greinfo[IFLA_GRE_LINK]);
 	}

 	while (argc > 0) {
 		if (!matches(*argv, "key")) {
 			unsigned uval;

 			NEXT_ARG();
 			iflags |= GRE_KEY;
 			oflags |= GRE_KEY;
 			if (strchr(*argv, '.'))
 				uval = get_addr32(*argv);
 			else {
 				if (get_unsigned(&uval, *argv, 0) < 0) {
 					fprintf(stderr,
 						"Invalid value for \"key\"\n");
 					exit(-1);
 				}
 				uval = htonl(uval);
 			}

 			ikey = okey = uval;
 		} else if (!matches(*argv, "ikey")) {
 			unsigned uval;

 			NEXT_ARG();
 			iflags |= GRE_KEY;
 			if (strchr(*argv, '.'))
 				uval = get_addr32(*argv);
 			else {
 				if (get_unsigned(&uval, *argv, 0)<0) {
 					fprintf(stderr, "invalid value of \"ikey\"\n");
 					exit(-1);
 				}
 				uval = htonl(uval);
 			}
 			ikey = uval;
 		} else if (!matches(*argv, "okey")) {
 			unsigned uval;

 			NEXT_ARG();
 			oflags |= GRE_KEY;
 			if (strchr(*argv, '.'))
 				uval = get_addr32(*argv);
 			else {
 				if (get_unsigned(&uval, *argv, 0)<0) {
 					fprintf(stderr, "invalid value of \"okey\"\n");
 					exit(-1);
 				}
 				uval = htonl(uval);
 			}
 			okey = uval;
 		} else if (!matches(*argv, "seq")) {
 			iflags |= GRE_SEQ;
 			oflags |= GRE_SEQ;
 		} else if (!matches(*argv, "iseq")) {
 			iflags |= GRE_SEQ;
 		} else if (!matches(*argv, "oseq")) {
 			oflags |= GRE_SEQ;
 		} else if (!matches(*argv, "csum")) {
 			iflags |= GRE_CSUM;
 			oflags |= GRE_CSUM;
 		} else if (!matches(*argv, "icsum")) {
 			iflags |= GRE_CSUM;
 		} else if (!matches(*argv, "ocsum")) {
 			oflags |= GRE_CSUM;
 		} else if (!matches(*argv, "nopmtudisc")) {
 			pmtudisc = 0;
 		} else if (!matches(*argv, "pmtudisc")) {
 			pmtudisc = 1;
 		} else if (!matches(*argv, "remote")) {
 			NEXT_ARG();
 			if (strcmp(*argv, "any"))
 				daddr = get_addr32(*argv);
 		} else if (!matches(*argv, "local")) {
 			NEXT_ARG();
 			if (strcmp(*argv, "any"))
 				saddr = get_addr32(*argv);
 		} else if (!matches(*argv, "dev")) {
 			NEXT_ARG();
 			link = if_nametoindex(*argv);
 			if (link == 0)
 				exit(-1);
 		} else if (!matches(*argv, "ttl") ||
 			   !matches(*argv, "hoplimit")) {
 			unsigned uval;

 			NEXT_ARG();
 			if (strcmp(*argv, "inherit") != 0) {
 				if (get_unsigned(&uval, *argv, 0))
 					invarg("invalid TTL\n", *argv);
 				if (uval > 255)
 					invarg("TTL must be <= 255\n", *argv);
 				ttl = uval;
 			}
 		} else if (!matches(*argv, "tos") ||
 			   !matches(*argv, "tclass") ||
 			   !matches(*argv, "dsfield")) {
 			__u32 uval;

 			NEXT_ARG();
 			if (strcmp(*argv, "inherit") != 0) {
 				if (rtnl_dsfield_a2n(&uval, *argv))
 					invarg("bad TOS value", *argv);
 				tos = uval;
 			} else
 				tos = 1;
 		} else
 			usage();
 		argc--; argv++;
 	}

 	if (!ikey && IN_MULTICAST(ntohl(daddr))) {
 		ikey = daddr;
 		iflags |= GRE_KEY;
 	}
 	if (!okey && IN_MULTICAST(ntohl(daddr))) {
 		okey = daddr;
 		oflags |= GRE_KEY;
 	}
 	if (IN_MULTICAST(ntohl(daddr)) && !saddr) {
 		fprintf(stderr, "Broadcast tunnel requires a source address.\n");
 		return -1;
 	}

 	addattr32(n, 1024, IFLA_GRE_IKEY, ikey);
 	addattr32(n, 1024, IFLA_GRE_OKEY, okey);
 	addattr_l(n, 1024, IFLA_GRE_IFLAGS, &iflags, 2);
 	addattr_l(n, 1024, IFLA_GRE_OFLAGS, &oflags, 2);
 	addattr_l(n, 1024, IFLA_GRE_LOCAL, &saddr, 4);
 	addattr_l(n, 1024, IFLA_GRE_REMOTE, &daddr, 4);
 	addattr_l(n, 1024, IFLA_GRE_PMTUDISC, &pmtudisc, 1);
 	if (link)
 		addattr32(n, 1024, IFLA_GRE_LINK, link);
 	addattr_l(n, 1024, IFLA_GRE_TTL, &ttl, 1);
 	addattr_l(n, 1024, IFLA_GRE_TOS, &tos, 1);

 	return 0;
 }

 static void gre_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 {
 	char s1[1024];
 	char s2[64];
 	const char *local = "any";
 	const char *remote = "any";
 	unsigned iflags = 0;
 	unsigned oflags = 0;

 	if (!tb)
 		return;

 	if (tb[IFLA_GRE_REMOTE]) {
 		unsigned addr = rta_getattr_u32(tb[IFLA_GRE_REMOTE]);

 		if (addr)
 			remote = format_host(AF_INET, 4, &addr, s1, sizeof(s1));
 	}

 	fprintf(f, "remote %s ", remote);

 	if (tb[IFLA_GRE_LOCAL]) {
 		unsigned addr = rta_getattr_u32(tb[IFLA_GRE_LOCAL]);

 		if (addr)
 			local = format_host(AF_INET, 4, &addr, s1, sizeof(s1));
 	}

 	fprintf(f, "local %s ", local);

 	if (tb[IFLA_GRE_LINK] && rta_getattr_u32(tb[IFLA_GRE_LINK])) {
 		unsigned link = rta_getattr_u32(tb[IFLA_GRE_LINK]);
 		const char *n = if_indextoname(link, s2);

 		if (n)
 			fprintf(f, "dev %s ", n);
 		else
 			fprintf(f, "dev %u ", link);
 	}

 	if (tb[IFLA_GRE_TTL] && rta_getattr_u8(tb[IFLA_GRE_TTL]))
 		fprintf(f, "ttl %d ", rta_getattr_u8(tb[IFLA_GRE_TTL]));
 	else
 		fprintf(f, "ttl inherit ");

 	if (tb[IFLA_GRE_TOS] && rta_getattr_u8(tb[IFLA_GRE_TOS])) {
 		int tos = rta_getattr_u8(tb[IFLA_GRE_TOS]);

 		fputs("tos ", f);
 		if (tos == 1)
 			fputs("inherit ", f);
 		else
 			fprintf(f, "0x%x ", tos);
 	}

 	if (tb[IFLA_GRE_PMTUDISC] &&
 	    !rta_getattr_u8(tb[IFLA_GRE_PMTUDISC]))
 		fputs("nopmtudisc ", f);

 	if (tb[IFLA_GRE_IFLAGS])
 		iflags = rta_getattr_u16(tb[IFLA_GRE_IFLAGS]);

 	if (tb[IFLA_GRE_OFLAGS])
 		oflags = rta_getattr_u16(tb[IFLA_GRE_OFLAGS]);

 	if ((iflags & GRE_KEY) && tb[IFLA_GRE_IKEY]) {
 		inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_IKEY]), s2, sizeof(s2));
 		fprintf(f, "ikey %s ", s2);
 	}

 	if ((oflags & GRE_KEY) && tb[IFLA_GRE_OKEY]) {
 		inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_OKEY]), s2, sizeof(s2));
 		fprintf(f, "okey %s ", s2);
 	}

 	if (iflags & GRE_SEQ)
 		fputs("iseq ", f);
 	if (oflags & GRE_SEQ)
 		fputs("oseq ", f);
 	if (iflags & GRE_CSUM)
 		fputs("icsum ", f);
 	if (oflags & GRE_CSUM)
 		fputs("ocsum ", f);
 }

 struct link_util gre_link_util = {
 	.id = "gre",
 	.maxattr = IFLA_GRE_MAX,
 	.parse_opt = gre_parse_opt,
 	.print_opt = gre_print_opt,
 };

 struct link_util gretap_link_util = {
 	.id = "gretap",
 	.maxattr = IFLA_GRE_MAX,
 	.parse_opt = gre_parse_opt,
 	.print_opt = gre_print_opt,
 };
	/*
	* link_gre.c gre driver module
	*
	* 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: Herbert Xu <herbert@gondor.apana.org.au>
	*
	*/

	#include <string.h>
	#include <net/if.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <arpa/inet.h>

	#include <linux/ip.h>
	#include <linux/if_tunnel.h>
	#include "rt_names.h"
	#include "utils.h"
	#include "ip_common.h"
	#include "tunnel.h"

	static void usage(void) __attribute__((noreturn));
	static void usage(void)
	{
	fprintf(stderr, "Usage: ip link { add \| set \| change \| replace \| del } NAME\n");
	fprintf(stderr, " type { gre \| gretap } [ remote ADDR ] [ local ADDR ]\n");
	fprintf(stderr, " [ [i\|o]seq ] [ [i\|o]key KEY ] [ [i\|o]csum ]\n");
	fprintf(stderr, " [ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ] [ dev PHYS_DEV ]\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "Where: NAME := STRING\n");
	fprintf(stderr, " ADDR := { IP_ADDRESS \| any }\n");
	fprintf(stderr, " TOS := { NUMBER \| inherit }\n");
	fprintf(stderr, " TTL := { 1..255 \| inherit }\n");
	fprintf(stderr, " KEY := { DOTTED_QUAD \| NUMBER }\n");
	exit(-1);
	}

	static int gre_parse_opt(struct link_util lu, int argc, char *argv,
	struct nlmsghdr *n)
	{
	struct {
	struct nlmsghdr n;
	struct ifinfomsg i;
	char buf[1024];
	} req;
	struct ifinfomsg ifi = (struct ifinfomsg )(n + 1);
	struct rtattr *tb[IFLA_MAX + 1];
	struct rtattr *linkinfo[IFLA_INFO_MAX+1];
	struct rtattr *greinfo[IFLA_GRE_MAX + 1];
	__u16 iflags = 0;
	__u16 oflags = 0;
	unsigned ikey = 0;
	unsigned okey = 0;
	unsigned saddr = 0;
	unsigned daddr = 0;
	unsigned link = 0;
	__u8 pmtudisc = 1;
	__u8 ttl = 0;
	__u8 tos = 0;
	int len;

	if (!(n->nlmsg_flags & NLM_F_CREATE)) {
	memset(&req, 0, sizeof(req));

	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(*ifi));
	req.n.nlmsg_flags = NLM_F_REQUEST;
	req.n.nlmsg_type = RTM_GETLINK;
	req.i.ifi_family = preferred_family;
	req.i.ifi_index = ifi->ifi_index;

	if (rtnl_talk(&rth, &req.n, 0, 0, &req.n) < 0) {
	get_failed:
	fprintf(stderr,
	"Failed to get existing tunnel info.\n");
	return -1;
	}

	len = req.n.nlmsg_len;
	len -= NLMSG_LENGTH(sizeof(*ifi));
	if (len < 0)
	goto get_failed;

	parse_rtattr(tb, IFLA_MAX, IFLA_RTA(&req.i), len);

	if (!tb[IFLA_LINKINFO])
	goto get_failed;

	parse_rtattr_nested(linkinfo, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);

	if (!linkinfo[IFLA_INFO_DATA])
	goto get_failed;

	parse_rtattr_nested(greinfo, IFLA_GRE_MAX,
	linkinfo[IFLA_INFO_DATA]);

	if (greinfo[IFLA_GRE_IKEY])
	ikey = rta_getattr_u32(greinfo[IFLA_GRE_IKEY]);

	if (greinfo[IFLA_GRE_OKEY])
	okey = rta_getattr_u32(greinfo[IFLA_GRE_OKEY]);

	if (greinfo[IFLA_GRE_IFLAGS])
	iflags = rta_getattr_u16(greinfo[IFLA_GRE_IFLAGS]);

	if (greinfo[IFLA_GRE_OFLAGS])
	oflags = rta_getattr_u16(greinfo[IFLA_GRE_OFLAGS]);

	if (greinfo[IFLA_GRE_LOCAL])
	saddr = rta_getattr_u32(greinfo[IFLA_GRE_LOCAL]);

	if (greinfo[IFLA_GRE_REMOTE])
	daddr = rta_getattr_u32(greinfo[IFLA_GRE_REMOTE]);

	if (greinfo[IFLA_GRE_PMTUDISC])
	pmtudisc = rta_getattr_u8(
	greinfo[IFLA_GRE_PMTUDISC]);

	if (greinfo[IFLA_GRE_TTL])
	ttl = rta_getattr_u8(greinfo[IFLA_GRE_TTL]);

	if (greinfo[IFLA_GRE_TOS])
	tos = rta_getattr_u8(greinfo[IFLA_GRE_TOS]);

	if (greinfo[IFLA_GRE_LINK])
	link = rta_getattr_u8(greinfo[IFLA_GRE_LINK]);
	}

	while (argc > 0) {
	if (!matches(*argv, "key")) {
	unsigned uval;

	NEXT_ARG();
	iflags \|= GRE_KEY;
	oflags \|= GRE_KEY;
	if (strchr(*argv, '.'))
	uval = get_addr32(*argv);
	else {
	if (get_unsigned(&uval, *argv, 0) < 0) {
	fprintf(stderr,
	"Invalid value for \"key\"\n");
	exit(-1);
	}
	uval = htonl(uval);
	}

	ikey = okey = uval;
	} else if (!matches(*argv, "ikey")) {
	unsigned uval;

	NEXT_ARG();
	iflags \|= GRE_KEY;
	if (strchr(*argv, '.'))
	uval = get_addr32(*argv);
	else {
	if (get_unsigned(&uval, *argv, 0)<0) {
	fprintf(stderr, "invalid value of \"ikey\"\n");
	exit(-1);
	}
	uval = htonl(uval);
	}
	ikey = uval;
	} else if (!matches(*argv, "okey")) {
	unsigned uval;

	NEXT_ARG();
	oflags \|= GRE_KEY;
	if (strchr(*argv, '.'))
	uval = get_addr32(*argv);
	else {
	if (get_unsigned(&uval, *argv, 0)<0) {
	fprintf(stderr, "invalid value of \"okey\"\n");
	exit(-1);
	}
	uval = htonl(uval);
	}
	okey = uval;
	} else if (!matches(*argv, "seq")) {
	iflags \|= GRE_SEQ;
	oflags \|= GRE_SEQ;
	} else if (!matches(*argv, "iseq")) {
	iflags \|= GRE_SEQ;
	} else if (!matches(*argv, "oseq")) {
	oflags \|= GRE_SEQ;
	} else if (!matches(*argv, "csum")) {
	iflags \|= GRE_CSUM;
	oflags \|= GRE_CSUM;
	} else if (!matches(*argv, "icsum")) {
	iflags \|= GRE_CSUM;
	} else if (!matches(*argv, "ocsum")) {
	oflags \|= GRE_CSUM;
	} else if (!matches(*argv, "nopmtudisc")) {
	pmtudisc = 0;
	} else if (!matches(*argv, "pmtudisc")) {
	pmtudisc = 1;
	} else if (!matches(*argv, "remote")) {
	NEXT_ARG();
	if (strcmp(*argv, "any"))
	daddr = get_addr32(*argv);
	} else if (!matches(*argv, "local")) {
	NEXT_ARG();
	if (strcmp(*argv, "any"))
	saddr = get_addr32(*argv);
	} else if (!matches(*argv, "dev")) {
	NEXT_ARG();
	link = if_nametoindex(*argv);
	if (link == 0)
	exit(-1);
	} else if (!matches(*argv, "ttl") \|\|
	!matches(*argv, "hoplimit")) {
	unsigned uval;

	NEXT_ARG();
	if (strcmp(*argv, "inherit") != 0) {
	if (get_unsigned(&uval, *argv, 0))
	invarg("invalid TTL\n", *argv);
	if (uval > 255)
	invarg("TTL must be <= 255\n", *argv);
	ttl = uval;
	}
	} else if (!matches(*argv, "tos") \|\|
	!matches(*argv, "tclass") \|\|
	!matches(*argv, "dsfield")) {
	__u32 uval;

	NEXT_ARG();
	if (strcmp(*argv, "inherit") != 0) {
	if (rtnl_dsfield_a2n(&uval, *argv))
	invarg("bad TOS value", *argv);
	tos = uval;
	} else
	tos = 1;
	} else
	usage();
	argc--; argv++;
	}

	if (!ikey && IN_MULTICAST(ntohl(daddr))) {
	ikey = daddr;
	iflags \|= GRE_KEY;
	}
	if (!okey && IN_MULTICAST(ntohl(daddr))) {
	okey = daddr;
	oflags \|= GRE_KEY;
	}
	if (IN_MULTICAST(ntohl(daddr)) && !saddr) {
	fprintf(stderr, "Broadcast tunnel requires a source address.\n");
	return -1;
	}

	addattr32(n, 1024, IFLA_GRE_IKEY, ikey);
	addattr32(n, 1024, IFLA_GRE_OKEY, okey);
	addattr_l(n, 1024, IFLA_GRE_IFLAGS, &iflags, 2);
	addattr_l(n, 1024, IFLA_GRE_OFLAGS, &oflags, 2);
	addattr_l(n, 1024, IFLA_GRE_LOCAL, &saddr, 4);
	addattr_l(n, 1024, IFLA_GRE_REMOTE, &daddr, 4);
	addattr_l(n, 1024, IFLA_GRE_PMTUDISC, &pmtudisc, 1);
	if (link)
	addattr32(n, 1024, IFLA_GRE_LINK, link);
	addattr_l(n, 1024, IFLA_GRE_TTL, &ttl, 1);
	addattr_l(n, 1024, IFLA_GRE_TOS, &tos, 1);

	return 0;
	}

	static void gre_print_opt(struct link_util lu, FILE f, struct rtattr *tb[])
	{
	char s1[1024];
	char s2[64];
	const char *local = "any";
	const char *remote = "any";
	unsigned iflags = 0;
	unsigned oflags = 0;

	if (!tb)
	return;

	if (tb[IFLA_GRE_REMOTE]) {
	unsigned addr = rta_getattr_u32(tb[IFLA_GRE_REMOTE]);

	if (addr)
	remote = format_host(AF_INET, 4, &addr, s1, sizeof(s1));
	}

	fprintf(f, "remote %s ", remote);

	if (tb[IFLA_GRE_LOCAL]) {
	unsigned addr = rta_getattr_u32(tb[IFLA_GRE_LOCAL]);

	if (addr)
	local = format_host(AF_INET, 4, &addr, s1, sizeof(s1));
	}

	fprintf(f, "local %s ", local);

	if (tb[IFLA_GRE_LINK] && rta_getattr_u32(tb[IFLA_GRE_LINK])) {
	unsigned link = rta_getattr_u32(tb[IFLA_GRE_LINK]);
	const char *n = if_indextoname(link, s2);

	if (n)
	fprintf(f, "dev %s ", n);
	else
	fprintf(f, "dev %u ", link);
	}

	if (tb[IFLA_GRE_TTL] && rta_getattr_u8(tb[IFLA_GRE_TTL]))
	fprintf(f, "ttl %d ", rta_getattr_u8(tb[IFLA_GRE_TTL]));
	else
	fprintf(f, "ttl inherit ");

	if (tb[IFLA_GRE_TOS] && rta_getattr_u8(tb[IFLA_GRE_TOS])) {
	int tos = rta_getattr_u8(tb[IFLA_GRE_TOS]);

	fputs("tos ", f);
	if (tos == 1)
	fputs("inherit ", f);
	else
	fprintf(f, "0x%x ", tos);
	}

	if (tb[IFLA_GRE_PMTUDISC] &&
	!rta_getattr_u8(tb[IFLA_GRE_PMTUDISC]))
	fputs("nopmtudisc ", f);

	if (tb[IFLA_GRE_IFLAGS])
	iflags = rta_getattr_u16(tb[IFLA_GRE_IFLAGS]);

	if (tb[IFLA_GRE_OFLAGS])
	oflags = rta_getattr_u16(tb[IFLA_GRE_OFLAGS]);

	if ((iflags & GRE_KEY) && tb[IFLA_GRE_IKEY]) {
	inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_IKEY]), s2, sizeof(s2));
	fprintf(f, "ikey %s ", s2);
	}

	if ((oflags & GRE_KEY) && tb[IFLA_GRE_OKEY]) {
	inet_ntop(AF_INET, RTA_DATA(tb[IFLA_GRE_OKEY]), s2, sizeof(s2));
	fprintf(f, "okey %s ", s2);
	}

	if (iflags & GRE_SEQ)
	fputs("iseq ", f);
	if (oflags & GRE_SEQ)
	fputs("oseq ", f);
	if (iflags & GRE_CSUM)
	fputs("icsum ", f);
	if (oflags & GRE_CSUM)
	fputs("ocsum ", f);
	}

	struct link_util gre_link_util = {
	.id = "gre",
	.maxattr = IFLA_GRE_MAX,
	.parse_opt = gre_parse_opt,
	.print_opt = gre_print_opt,
	};

	struct link_util gretap_link_util = {
	.id = "gretap",
	.maxattr = IFLA_GRE_MAX,
	.parse_opt = gre_parse_opt,
	.print_opt = gre_print_opt,
	};