Check for invalid SAM destination

This closes #208

SAM.cpp

@@ -343,7 +343,9 @@ namespace client
 		if (m_Session)
 		{
 			i2p::data::IdentityEx dest;
-			dest.FromBase64 (destination);
+			size_t len = dest.FromBase64(destination);
+			if (len > 0)
+			{
 				context.GetAddressBook().InsertAddress(dest);
 				auto leaseSet = m_Session->localDestination->FindLeaseSet(dest.GetIdentHash());
 				if (leaseSet)
@@ -355,6 +357,9 @@ namespace client
 						shared_from_this(), std::placeholders::_1));
 				}
 			}
+			else
+				SendMessageReply(SAM_SESSION_STATUS_INVALID_KEY, strlen(SAM_SESSION_STATUS_INVALID_KEY), true);
+		}
 		else
 			SendMessageReply (SAM_STREAM_STATUS_INVALID_ID, strlen(SAM_STREAM_STATUS_INVALID_ID), true);		
 	}

SAM.h

@@ -28,6 +28,7 @@ namespace client
 	const char SAM_SESSION_CREATE_REPLY_OK[] = "SESSION STATUS RESULT=OK DESTINATION=%s\n";
 	const char SAM_SESSION_CREATE_DUPLICATED_ID[] = "SESSION STATUS RESULT=DUPLICATED_ID\n";
 	const char SAM_SESSION_CREATE_DUPLICATED_DEST[] = "SESSION STATUS RESULT=DUPLICATED_DEST\n";	
+	const char SAM_SESSION_STATUS_INVALID_KEY[] = "SESSION STATUS RESULT=INVALID_KEY\n";
 	const char SAM_STREAM_CONNECT[] = "STREAM CONNECT";
 	const char SAM_STREAM_STATUS_OK[] = "STREAM STATUS RESULT=OK\n";
 	const char SAM_STREAM_STATUS_INVALID_ID[] = "STREAM STATUS RESULT=INVALID_ID\n";