tipc: support interface name when activating UDP bearer

Support for indicating interface name has an ip address in parallel
with specifying ip address when activating UDP bearer.
This liberates the user from keeping track of the current ip address
for each device.

Old command syntax:
$tipc bearer enable media udp name NAME localip IP

New command syntax:
$tipc bearer enable media udp name NAME [localip IP|dev DEVICE]

v2:
    - Removed initial value for fd
    - Fixed the returning value for cmd_bearer_validate_and_get_addr
      to make its consistent with using: zero or non-zero
v3: - Switch to use helper 'get_ifname' to retrieve interface name
v4: - Replace legacy SIOCGIFADDR by netlink
v5: - Fix leaky rtnl_handle

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: David Ahern <dsahern@gmail.com>

Author: Hoang Le

tipc/bearer.c

@@ -19,10 +19,12 @@
 #include <linux/tipc_netlink.h>
 #include <linux/tipc.h>
 #include <linux/genetlink.h>
+#include <linux/if.h>
 
 #include <libmnl/libmnl.h>
 #include <sys/socket.h>
 
+#include "utils.h"
 #include "cmdl.h"
 #include "msg.h"
 #include "bearer.h"
@@ -68,7 +70,7 @@ static void cmd_bearer_enable_l2_help(struct cmdl *cmdl, char *media)
 static void cmd_bearer_enable_udp_help(struct cmdl *cmdl, char *media)
 {
 	fprintf(stderr,
-		"Usage: %s bearer enable [OPTIONS] media %s name NAME localip IP [UDP OPTIONS]\n\n"
+		"Usage: %s bearer enable [OPTIONS] media %s name NAME [localip IP|device DEVICE] [UDP OPTIONS]\n\n"
 		"OPTIONS\n"
 		" domain DOMAIN		- Discovery domain\n"
 		" priority PRIORITY	- Bearer priority\n\n"
@@ -119,6 +121,76 @@ static int generate_multicast(short af, char *buf, int bufsize)
 	return 0;
 }
 
+static struct ifreq ifr;
+static int nl_dump_req_filter(struct nlmsghdr *nlh, int reqlen)
+{
+	struct ifaddrmsg *ifa = NLMSG_DATA(nlh);
+
+	ifa->ifa_index = ifr.ifr_ifindex;
+
+	return 0;
+}
+
+static int nl_dump_addr_filter(struct nlmsghdr *nlh, void *arg)
+{
+	struct ifaddrmsg *ifa = NLMSG_DATA(nlh);
+	char *r_addr = (char *)arg;
+	int len = nlh->nlmsg_len;
+	struct rtattr *addr_attr;
+
+	if (ifr.ifr_ifindex != ifa->ifa_index)
+		return 0;
+
+	if (strlen(r_addr) > 0)
+		return 0;
+
+	addr_attr = parse_rtattr_one(IFA_ADDRESS, IFA_RTA(ifa),
+				     len - NLMSG_LENGTH(sizeof(*ifa)));
+	if (!addr_attr)
+		return 0;
+
+	if (ifa->ifa_family == AF_INET) {
+		struct sockaddr_in ip4addr;
+		memcpy(&ip4addr.sin_addr, RTA_DATA(addr_attr),
+		       sizeof(struct in_addr));
+		inet_ntop(AF_INET, &ip4addr.sin_addr, r_addr,
+			  INET_ADDRSTRLEN);
+	} else if (ifa->ifa_family == AF_INET6) {
+		struct sockaddr_in6 ip6addr;
+		memcpy(&ip6addr.sin6_addr, RTA_DATA(addr_attr),
+		       sizeof(struct in6_addr));
+		inet_ntop(AF_INET6, &ip6addr.sin6_addr, r_addr,
+			  INET6_ADDRSTRLEN);
+	}
+	return 0;
+}
+
+static int cmd_bearer_validate_and_get_addr(const char *name, char *r_addr)
+{
+	struct rtnl_handle rth = { .fd = -1 };
+	int err = -1;
+
+	memset(&ifr, 0, sizeof(ifr));
+	if (!name || !r_addr || get_ifname(ifr.ifr_name, name))
+		return err;
+
+	ifr.ifr_ifindex = ll_name_to_index(ifr.ifr_name);
+	if (!ifr.ifr_ifindex)
+		return err;
+
+	/* remove from cache */
+	ll_drop_by_index(ifr.ifr_ifindex);
+
+	if ((err = rtnl_open(&rth, 0)) < 0)
+		return err;
+
+	if ((err = rtnl_addrdump_req(&rth, AF_UNSPEC, nl_dump_req_filter)) > 0)
+		err = rtnl_dump_filter(&rth, nl_dump_addr_filter, r_addr);
+
+	rtnl_close(&rth);
+	return err;
+}
+
 static int nl_add_udp_enable_opts(struct nlmsghdr *nlh, struct opt *opts,
 				  struct cmdl *cmdl)
 {
@@ -136,13 +208,25 @@ static int nl_add_udp_enable_opts(struct nlmsghdr *nlh, struct opt *opts,
 		.ai_family = AF_UNSPEC,
 		.ai_socktype = SOCK_DGRAM
 	};
+	char addr[INET6_ADDRSTRLEN] = {0};
 
-	if (!(opt = get_opt(opts, "localip"))) {
-		fprintf(stderr, "error, udp bearer localip missing\n");
-		cmd_bearer_enable_udp_help(cmdl, "udp");
+	opt = get_opt(opts, "device");
+	if (opt && cmd_bearer_validate_and_get_addr(opt->val, addr) < 0) {
+		fprintf(stderr, "error, no device name available\n");
 		return -EINVAL;
 	}
-	locip = opt->val;
+
+	if (strlen(addr) > 0) {
+		locip = addr;
+	} else {
+		opt = get_opt(opts, "localip");
+		if (!opt) {
+			fprintf(stderr, "error, udp bearer localip/device missing\n");
+			cmd_bearer_enable_udp_help(cmdl, "udp");
+			return -EINVAL;
+		}
+		locip = opt->val;
+	}
 
 	if ((opt = get_opt(opts, "remoteip")))
 		remip = opt->val;