This patch adds a mechanism to get the device address length via
netlink. This is necessary for device type 6LoWPAN which can have
different device address lengths.
---
device-linux.c | 16 +++++++++++++--
netlink.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
netlink.h | 1 +
3 files changed, 79 insertions(+), 2 deletions(-)
diff --git a/device-linux.c b/device-linux.c
index 7301927..1ccb207 100644
--- a/device-linux.c
+++ b/device-linux.c
@@ -17,6 +17,7 @@
#include "radvd.h"
#include "defaults.h"
#include "pathnames.h"
+#include "netlink.h"
#ifndef IPV6_ADDR_LINKLOCAL
#define IPV6_ADDR_LINKLOCAL 0x0020U
@@ -84,8 +85,19 @@ int update_device_info(int sock, struct Interface *iface)
break;
#endif /* ARPHDR_ARCNET */
case ARPHRD_6LOWPAN:
- iface->sllao.if_hwaddr_len = 64;
- iface->sllao.if_prefix_len = 64;
+#ifdef HAVE_NETLINK
+ /* hwaddr length differs on some L2 type lets detect them */
+ iface->sllao.if_hwaddr_len = netlink_get_device_addr_len(iface);
+ if (iface->sllao.if_hwaddr_len != -1) {
+ iface->sllao.if_hwaddr_len *= 8;
+ iface->sllao.if_prefix_len = 64;
+ } else {
+ iface->sllao.if_prefix_len = -1;
+ }
+#else
+ iface->sllao.if_hwaddr_len = -1;
+ iface->sllao.if_prefix_len = -1;
+#endif
break;
default:
iface->sllao.if_hwaddr_len = -1;
diff --git a/netlink.c b/netlink.c
index 80d2254..d07a0b8 100644
--- a/netlink.c
+++ b/netlink.c
@@ -32,6 +32,70 @@
#define SOL_NETLINK 270
#endif
+struct iplink_req {
+ struct nlmsghdr n;
+ struct ifinfomsg i;
+ char buf[1024];
+};
+
+int netlink_get_device_addr_len(struct Interface *iface)
+{
+ struct iplink_req req = {};
+ struct iovec iov = { &req, sizeof(req) };
+ struct sockaddr_nl sa = {};
+ struct msghdr msg = { (void *)&sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+ int sock, len, addr_len = -1;
+ unsigned short type;
+ char answer[32768];
+ struct rtattr *tb;
+
+ /* nl_pid (for linux kernel) and nl_groups (unicast) should be zero */
+ sa.nl_family = AF_NETLINK;
+ req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+ req.n.nlmsg_flags = NLM_F_REQUEST;
+ req.n.nlmsg_type = RTM_GETLINK;
+ req.i.ifi_index = iface->props.if_index;
+
+ sock = netlink_socket();
+ if (sock == -1)
+ return -1;
+
+ len = sendmsg(sock, &msg, 0);
+ if (len == -1) {
+ flog(LOG_ERR, "netlink: sendmsg for addr_len failed: %s", strerror(errno));
+ close(sock);
+ goto out;
+ }
+
+ iov.iov_base = answer;
+ iov.iov_len = sizeof(answer);
+ len = recvmsg(sock, &msg, 0);
+ if (len == -1) {
+ flog(LOG_ERR, "netlink: recvmsg for addr_len failed: %s", strerror(errno));
+ close(sock);
+ goto out;
+ }
+
+ if (len < NLMSG_LENGTH(sizeof(struct ifinfomsg)))
+ goto out;
+ len -= NLMSG_LENGTH(sizeof(struct ifinfomsg));
+
+ tb = (struct rtattr *)(answer + NLMSG_LENGTH(sizeof(struct ifinfomsg)));
+ while (RTA_OK(tb, len)) {
+ type = tb->rta_type & ~NLA_F_NESTED;
+ if (type == IFLA_ADDRESS) {
+ addr_len = RTA_PAYLOAD(tb);
+ break;
+ }
+ tb = RTA_NEXT(tb, len);
+ }
+
+out:
+ close(sock);
+
+ return addr_len;
+}
+
void process_netlink_msg(int sock, struct Interface * ifaces)
{
char buf[4096];
diff --git a/netlink.h b/netlink.h
index e2b706e..c693a10 100644
--- a/netlink.h
+++ b/netlink.h
@@ -17,5 +17,6 @@
#include "radvd.h"
+int netlink_get_device_addr_len(struct Interface *iface);
void process_netlink_msg(int sock, struct Interface * ifaces);
int netlink_socket(void);
--
2.9.2
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