mctp-netlink: Store interface physical address in linkmap

Normally, extended addressing is used to respond to requests. We can
take the physical address len from the requester's sockaddr.
However, when we want to send extended address on an interface,
we do not have that information in linkmap.

This stores interface address from netlink inside linkmap.

Tested: Discovery Notify message is filled with correct address
(see next commit)

Signed-off-by: Khang Nguyen Duy <[email protected]>

Author: Khang Nguyen

src/mctp-netlink.c

@@ -23,6 +23,8 @@
 struct linkmap_entry {
 	int	ifindex;
 	char	ifname[IFNAMSIZ+1];
+	uint8_t	ifaddr[MAX_ADDR_LEN];
+	size_t	ifaddr_len;
 	int	net;
 	bool 	up;
 
@@ -53,8 +55,9 @@ static int fill_local_addrs(mctp_nl *nl);
 static int fill_linkmap(mctp_nl *nl);
 static void sort_linkmap(mctp_nl *nl);
 static int linkmap_add_entry(mctp_nl *nl, struct ifinfomsg *info,
-		const char *ifname, size_t ifname_len, int net,
-		bool up);
+			     const char *ifname, size_t ifname_len,
+			     uint8_t *ifaddr, size_t ifaddr_len, int net,
+			     bool up);
 static struct linkmap_entry *entry_byindex(const mctp_nl *nl,
 	int index);
 
@@ -679,8 +682,9 @@ static int parse_getlink_dump(mctp_nl *nl, struct nlmsghdr *nlh, uint32_t len)
 
 	for (; NLMSG_OK(nlh, len); nlh = NLMSG_NEXT(nlh, len)) {
 		struct rtattr *rta, *rt_nest, *rt_mctp;
+		uint8_t *ifaddr;
 		char *ifname;
-		size_t ifname_len, rlen, nlen, mlen;
+		size_t ifname_len, ifaddr_len, rlen, nlen, mlen;
 		uint32_t net;
 		bool up;
 
@@ -722,8 +726,13 @@ static int parse_getlink_dump(mctp_nl *nl, struct nlmsghdr *nlh, uint32_t len)
 			continue;
 		}
 		ifname_len = strnlen(ifname, ifname_len);
+
+		ifaddr = mctp_get_rtnlmsg_attr(IFLA_ADDRESS, rta, rlen,
+					       &ifaddr_len);
+
 		up = info->ifi_flags & IFF_UP;
-		linkmap_add_entry(nl, info, ifname, ifname_len, net, up);
+		linkmap_add_entry(nl, info, ifname, ifname_len, ifaddr,
+				  ifaddr_len, net, up);
 	}
 	// Not done.
 	return 1;
@@ -927,6 +936,16 @@ const char* mctp_nl_if_byindex(const mctp_nl *nl, int index)
 	return NULL;
 }
 
+uint8_t *mctp_nl_ifaddr_byindex(const mctp_nl *nl, int index, size_t *ret_len)
+{
+	struct linkmap_entry *entry = entry_byindex(nl, index);
+	if (entry) {
+		*ret_len = entry->ifaddr_len;
+		return entry->ifaddr;
+	}
+	return NULL;
+}
+
 int mctp_nl_net_byindex(const mctp_nl *nl, int index)
 {
 	struct linkmap_entry *entry = entry_byindex(nl, index);
@@ -1054,8 +1073,9 @@ int *mctp_nl_if_list(const mctp_nl *nl, size_t *ret_num_ifs)
 }
 
 static int linkmap_add_entry(mctp_nl *nl, struct ifinfomsg *info,
-		const char *ifname, size_t ifname_len, int net,
-		bool up)
+			     const char *ifname, size_t ifname_len,
+			     uint8_t *ifaddr, size_t ifaddr_len, int net,
+			     bool up)
 {
 	struct linkmap_entry *entry;
 	size_t newsz;
@@ -1067,6 +1087,12 @@ static int linkmap_add_entry(mctp_nl *nl, struct ifinfomsg *info,
 		return -1;
 	}
 
+	if (ifaddr_len > MAX_ADDR_LEN) {
+		warnx("linkmap, too long ifaddr (%zu bytes long, expected max %d bytes)",
+		      ifaddr_len, MAX_ADDR_LEN);
+		return -1;
+	}
+
 	if (net <= 0) {
 		warnx("Bad network ID %d for %*s", net, (int)ifname_len, ifname);
 		return -1;
@@ -1088,6 +1114,8 @@ static int linkmap_add_entry(mctp_nl *nl, struct ifinfomsg *info,
 	entry = &nl->linkmap[idx];
 	memset(entry, 0, sizeof(*entry));
 	snprintf(entry->ifname, IFNAMSIZ, "%*s", (int)ifname_len, ifname);
+	memcpy(entry->ifaddr, ifaddr, ifaddr_len);
+	entry->ifaddr_len = ifaddr_len;
 	entry->ifindex = info->ifi_index;
 	entry->net = net;
 	entry->up = up;

src/mctp-netlink.h

@@ -62,6 +62,7 @@ int mctp_nl_recv_all(mctp_nl *nl, int sd,
 /* Lookup MCTP interfaces */
 int mctp_nl_ifindex_byname(const mctp_nl *nl, const char *ifname);
 const char* mctp_nl_if_byindex(const mctp_nl *nl, int index);
+uint8_t *mctp_nl_ifaddr_byindex(const mctp_nl *nl, int index, size_t *ret_len);
 int mctp_nl_net_byindex(const mctp_nl *nl, int index);
 bool mctp_nl_up_byindex(const mctp_nl *nl, int index);
 /* Caller to free */