Fix/workaround for issue #910 Publisher crashes when curve encryption is enabled and SubscribeToAnyTopic is used in the subscriber socket

Author: Jesper Glintborg

src/NetMQ/Core/Patterns/XPub.cs

@@ -176,8 +176,8 @@ protected override void XReadActivated(Pipe pipe)
                     else
                     {
                         var unique = sub[0] == 0
-                            ? m_subscriptions.Remove(sub.Slice(1), pipe)
-                            : m_subscriptions.Add(sub.Slice(1), pipe);
+                            ? m_subscriptions.Remove(size == 1 ? new Span<byte>(): sub.Slice(1), pipe)
+                            : m_subscriptions.Add(size == 1 ? new Span<byte>() : sub.Slice(1), pipe);
 
                         // If the subscription is not a duplicate, store it so that it can be
                         // passed to used on next recv call.

src/NetMQ/Core/Patterns/XSub.cs

@@ -19,6 +19,7 @@ You should have received a copy of the GNU Lesser General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+using System;
 using System.Diagnostics;
 using NetMQ.Core.Patterns.Utils;
 
@@ -170,15 +171,15 @@ protected override bool XSend(ref Msg msg)
                 if (!m_moreOut && size > 0 && msg[0] == 1)
                 {
                     // Process the subscription.
-                    if (m_subscriptions.Add(msg.Slice(1)))
+                    if (m_subscriptions.Add(size == 1 ? new Span<byte>() : msg.Slice(1)))
                     {
                         m_distribution.SendToAll(ref msg);
                         return true;
                     }
                 }
                 else if (!m_moreOut && size > 0 && msg[0] == 0)
                 {
-                    if (m_subscriptions.Remove(msg.Slice(1)))
+                    if (m_subscriptions.Remove(size == 1 ?new Span<byte>() : msg.Slice(1)))
                     {
                         m_distribution.SendToAll(ref msg);
                         return true;