From: Robert Wolf <r.wolf.debian@atlas.cz>
Date: Mon, 11 Jan 2016 14:21:40 +0100
Subject: Server should not bind control port if there is no shared secret

And add two additional check of shared secret
- checks validity of the read shared secret and set ctlkey structure
  pointer not NULL only if there is really any shared secret.
- check if ctlkey is NULL or if shared secret is NULL or empty
  (pointer is not NULL, but there are no data - length is 0).

This resolved upstream issue #36:
- https://sourceforge.net/p/wide-dhcpv6/bugs/36

Closes: #799080
---
 dhcp6_ctl.c | 16 +++++++++++++---
 dhcp6s.c    |  2 +-
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/dhcp6_ctl.c b/dhcp6_ctl.c
index dc6c323..056b550 100644
--- a/dhcp6_ctl.c
+++ b/dhcp6_ctl.c
@@ -166,9 +166,14 @@ dhcp6_ctl_authinit(keyfile, keyinfop, digestlenp)
 		    strerror(errno));
 		return (-1);
 	}
-	if (fgets(line, sizeof(line), fp) == NULL && ferror(fp)) {
-		debug_printf(LOG_ERR, FNAME, "failed to read key file: %s",
-		    strerror(errno));
+	if (fgets(line, sizeof(line), fp) == NULL) {
+		if (ferror(fp)) {
+			debug_printf(LOG_ERR, FNAME, "failed to read key file: %s",
+			    strerror(errno));
+		} else {
+			debug_printf(LOG_INFO, FNAME, "no shared key. shared key file "
+			    "is empty. dhcp6s will not listen on a control port.");
+		}
 		goto fail;
 	}
 	if ((secretlen = base64_decodestring(line, secret, sizeof(secret)))
@@ -176,6 +181,11 @@ dhcp6_ctl_authinit(keyfile, keyinfop, digestlenp)
 		debug_printf(LOG_ERR, FNAME, "failed to decode base64 string");
 		goto fail;
 	}
+	if (secretlen == 0) {
+		debug_printf(LOG_INFO, FNAME, "no shared key found. dhcp6s will "
+		    "not listen on a control port.");
+		goto fail;
+	}
 	if ((ctlkey = malloc(sizeof(*ctlkey))) == NULL) {
 		debug_printf(LOG_WARNING, FNAME, "failed to allocate control key");
 		goto fail;
diff --git a/dhcp6s.c b/dhcp6s.c
index a230d75..1942d8d 100644
--- a/dhcp6s.c
+++ b/dhcp6s.c
@@ -573,7 +573,7 @@ server6_init()
 	freeaddrinfo(res);
 
 	/* set up control socket */
-	if (ctlkey == NULL)
+	if (ctlkey == NULL || ctlkey->secret == NULL || ctlkey->secretlen == 0)
 		debug_printf(LOG_NOTICE, FNAME, "skip opening control port");
 	else if (dhcp6_ctl_init(ctladdr, ctlport,
 	    DHCP6CTL_DEF_COMMANDQUEUELEN, &ctlsock)) {