busybox: backport 'ip rule suppress_{prefixlength, ifgroup}'

This is a backport from the busybox repository
(192dce4b84fb32346ebc5194de7daa5da3b8d1b4); it enables the use of the
suppress_{prefixlength,ifgroup} flags for policy routing rules.

Signed-off-by: Stefan Tomanek <[email protected]>

package/utils/busybox/patches/302-ip-rule-add-suppress-prefixlength.patch

@@ -0,0 +1,145 @@
+From dbac30c3784c267bbe44a2a3ebed4e827c8fe82a Mon Sep 17 00:00:00 2001
+From: Stefan Tomanek <[email protected]>
+Date: Tue, 13 Jun 2017 19:06:09 +0200
+Subject: [PATCH] ip rule: add suppress_{prefixlength,ifgroup} options
+
+(cherry-picked from 192dce4b84fb32346ebc5194de7daa5da3b8d1b4)
+
+function                                             old     new   delta
+iprule_modify                                        816     887     +71
+print_rule                                           610     680     +70
+------------------------------------------------------------------------------
+(add/remove: 0/0 grow/shrink: 2/0 up/down: 141/0)             Total: 141 bytes
+
+Signed-off-by: Stefan Tomanek <[email protected]>
+Signed-off-by: Denys Vlasenko <[email protected]>
+---
+ networking/libiproute/iprule.c | 73 ++++++++++++++++++++++++++----------------
+ 1 file changed, 46 insertions(+), 27 deletions(-)
+
+--- a/networking/libiproute/iprule.c
++++ b/networking/libiproute/iprule.c
+@@ -17,25 +17,32 @@
+ #include <netinet/ip.h>
+ #include <arpa/inet.h>
+ 
++/* from <linux/fib_rules.h>: */
++#define FRA_SUPPRESS_IFGROUP   13
++#define FRA_SUPPRESS_PREFIXLEN 14
++
+ #include "ip_common.h"  /* #include "libbb.h" is inside */
+ #include "rt_names.h"
+ #include "utils.h"
+ 
+-/*
+-static void usage(void) __attribute__((noreturn));
+-
+-static void usage(void)
+-{
+-	fprintf(stderr, "Usage: ip rule [ list | add | del ] SELECTOR ACTION\n");
+-	fprintf(stderr, "SELECTOR := [ from PREFIX ] [ to PREFIX ] [ tos TOS ] [ fwmark FWMARK ]\n");
+-	fprintf(stderr, "            [ dev STRING ] [ pref NUMBER ]\n");
+-	fprintf(stderr, "ACTION := [ table TABLE_ID ] [ nat ADDRESS ]\n");
+-	fprintf(stderr, "          [ prohibit | reject | unreachable ]\n");
+-	fprintf(stderr, "          [ realms [SRCREALM/]DSTREALM ]\n");
+-	fprintf(stderr, "TABLE_ID := [ local | main | default | NUMBER ]\n");
+-	exit(-1);
+-}
+-*/
++/* If you add stuff here, update iprule_full_usage */
++static const char keywords[] ALIGN1 =
++	"from\0""to\0""preference\0""order\0""priority\0"
++	"tos\0""fwmark\0""realms\0""table\0""lookup\0"
++	"suppress_prefixlength\0""suppress_ifgroup\0"
++	"dev\0""iif\0""nat\0""map-to\0""type\0""help\0"
++	;
++#define keyword_preference            (keywords           + sizeof("from") + sizeof("to"))
++#define keyword_fwmark                (keyword_preference + sizeof("preference") + sizeof("order") + sizeof("priority") + sizeof("tos"))
++#define keyword_realms                (keyword_fwmark     + sizeof("fwmark"))
++#define keyword_suppress_prefixlength (keyword_realms     + sizeof("realms") + sizeof("table") + sizeof("lookup"))
++#define keyword_suppress_ifgroup      (keyword_suppress_prefixlength + sizeof("suppress_prefixlength"))
++enum {
++	ARG_from = 1, ARG_to, ARG_preference, ARG_order, ARG_priority,
++	ARG_tos, ARG_fwmark, ARG_realms, ARG_table, ARG_lookup,
++	ARG_suppress_prefixlength, ARG_suppress_ifgroup,
++	ARG_dev, ARG_iif, ARG_nat, ARG_map_to, ARG_type, ARG_help,
++};
+ 
+ static int FAST_FUNC print_rule(const struct sockaddr_nl *who UNUSED_PARAM,
+ 					struct nlmsghdr *n, void *arg UNUSED_PARAM)
+@@ -119,6 +126,17 @@ static int FAST_FUNC print_rule(const st
+ 	else if (r->rtm_table)
+ 		printf("lookup %s ", rtnl_rttable_n2a(r->rtm_table));
+ 
++	if (tb[FRA_SUPPRESS_PREFIXLEN]) {
++		int pl = *(uint32_t*)RTA_DATA(tb[FRA_SUPPRESS_PREFIXLEN]);
++		if (pl != -1)
++			printf("%s %d ", keyword_suppress_prefixlength, pl);
++	}
++	if (tb[FRA_SUPPRESS_IFGROUP]) {
++		int grp = *(uint32_t*)RTA_DATA(tb[FRA_SUPPRESS_IFGROUP]);
++		if (grp != -1)
++			printf("%s %d ", keyword_suppress_ifgroup, grp);
++	}
++
+ 	if (tb[RTA_FLOW]) {
+ 		uint32_t to = *(uint32_t*)RTA_DATA(tb[RTA_FLOW]);
+ 		uint32_t from = to>>16;
+@@ -174,15 +192,6 @@ static int iprule_list(char **argv)
+ /* Return value becomes exitcode. It's okay to not return at all */
+ static int iprule_modify(int cmd, char **argv)
+ {
+-	static const char keywords[] ALIGN1 =
+-		"from\0""to\0""preference\0""order\0""priority\0"
+-		"tos\0""fwmark\0""realms\0""table\0""lookup\0""dev\0"
+-		"iif\0""nat\0""map-to\0""type\0""help\0";
+-	enum {
+-		ARG_from = 1, ARG_to, ARG_preference, ARG_order, ARG_priority,
+-		ARG_tos, ARG_fwmark, ARG_realms, ARG_table, ARG_lookup, ARG_dev,
+-		ARG_iif, ARG_nat, ARG_map_to, ARG_type, ARG_help
+-	};
+ 	bool table_ok = 0;
+ 	struct rtnl_handle rth;
+ 	struct {
+@@ -232,7 +241,7 @@ static int iprule_modify(int cmd, char *
+ 		) {
+ 			uint32_t pref;
+ 			NEXT_ARG();
+-			pref = get_u32(*argv, "preference");
++			pref = get_u32(*argv, keyword_preference);
+ 			addattr32(&req.n, sizeof(req), RTA_PRIORITY, pref);
+ 		} else if (key == ARG_tos) {
+ 			uint32_t tos;
+@@ -243,13 +252,13 @@ static int iprule_modify(int cmd, char *
+ 		} else if (key == ARG_fwmark) {
+ 			uint32_t fwmark;
+ 			NEXT_ARG();
+-			fwmark = get_u32(*argv, "fwmark");
++			fwmark = get_u32(*argv, keyword_fwmark);
+ 			addattr32(&req.n, sizeof(req), RTA_PROTOINFO, fwmark);
+ 		} else if (key == ARG_realms) {
+ 			uint32_t realm;
+ 			NEXT_ARG();
+ 			if (get_rt_realms(&realm, *argv))
+-				invarg_1_to_2(*argv, "realms");
++				invarg_1_to_2(*argv, keyword_realms);
+ 			addattr32(&req.n, sizeof(req), RTA_FLOW, realm);
+ 		} else if (key == ARG_table ||
+ 			   key == ARG_lookup
+@@ -265,6 +274,16 @@ static int iprule_modify(int cmd, char *
+ 				addattr32(&req.n, sizeof(req), RTA_TABLE, tid);
+ 			}
+ 			table_ok = 1;
++		} else if (key == ARG_suppress_prefixlength) {
++			int prefix_length;
++			NEXT_ARG();
++			prefix_length = get_u32(*argv, keyword_suppress_prefixlength);
++			addattr32(&req.n, sizeof(req), FRA_SUPPRESS_PREFIXLEN, prefix_length);
++		} else if (key == ARG_suppress_ifgroup) {
++			int grp;
++			NEXT_ARG();
++			grp = get_u32(*argv, keyword_suppress_ifgroup);
++			addattr32(&req.n, sizeof(req), FRA_SUPPRESS_IFGROUP, grp);
+ 		} else if (key == ARG_dev ||
+ 			   key == ARG_iif
+ 		) {