tun.c: tun_addaddr: Fix segfault and wrong usage of tun_nlattr

First of all, dstaddr can be NULL, avoid copying it in that case.
Second, we want to copy the addr data, not the pointer. I tested it and
the IP was not added (not shown in ip addr) until I copied the content
instead of the address.

Change-Id: I8da637b155f0e913cab6c5b0dde355c9f33375b5

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/tun.c b/lib/tun.c
index d8e4b62..3081575 100644
--- a/lib/tun.c
+++ b/lib/tun.c
@@ -333,8 +333,9 @@ int tun_addaddr(struct tun_t *this,
 		return -1;
 	}
 
-	tun_nlattr(&req.n, sizeof(req), IFA_ADDRESS, addr, sizeof(addr));
-	tun_nlattr(&req.n, sizeof(req), IFA_LOCAL, dstaddr, sizeof(dstaddr));
+	tun_nlattr(&req.n, sizeof(req), IFA_ADDRESS, addr, sizeof(*addr));
+	if (dstaddr)
+		tun_nlattr(&req.n, sizeof(req), IFA_LOCAL, dstaddr, sizeof(*dstaddr));
 
 	if ((fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) < 0) {
 		SYS_ERR(DTUN, LOGL_ERROR, errno, "socket() failed");