aos/sctp: handle multiple recvmsg calls

Change-Id: I9929c49559f28b5595c8343f1c8e244ce37f7c15
diff --git a/aos/network/sctp_lib.h b/aos/network/sctp_lib.h
index 9a1274a..265d1f5 100644
--- a/aos/network/sctp_lib.h
+++ b/aos/network/sctp_lib.h
@@ -52,6 +52,8 @@
     return reinterpret_cast<const uint8_t *>(&actual_data[0].data);
   }
 
+  uint32_t partial_deliveries = 0;
+
   // Returns a human readable peer IP address.
   std::string PeerAddress() const;
 
@@ -70,7 +72,7 @@
 void LogSctpStatus(int fd, sctp_assoc_t assoc_id);
 
 // Read and allocate a message.
-aos::unique_c_ptr<Message> ReadSctpMessage(int fd, int max_size);
+aos::unique_c_ptr<Message> ReadSctpMessage(int fd, size_t max_size);
 
 // Returns the max network buffer available for reading for a socket.
 size_t ReadRMemMax();