fruity: Enable lwIP TCP timestamps and SACK

To align with the Linux IP stack's defaults.

src/fruity/network-stack.vala

@@ -518,6 +518,7 @@ namespace Frida.Fruity {
 					if (self != null)
 						self->on_error (err);
 				});
+				pcb.set_flags (TIMESTAMP | SACK);
 				pcb.nagle_disable ();
 				pcb.bind_netif (&netstack.handle);
 

vapi/lwip.vapi

@@ -189,6 +189,8 @@ namespace LWIP {
 		[CCode (cname = "tcp_err")]
 		public void set_error_callback (ErrorFunc f);
 
+		public void set_flags (Flags flags);
+
 		public void nagle_disable ();
 		public void nagle_enable ();
 
@@ -221,6 +223,24 @@ namespace LWIP {
 		[CCode (cname = "tcp_connected_fn", has_target = false)]
 		public delegate ErrorCode ConnectedFunc (void * user_data, TcpPcb pcb, ErrorCode err);
 
+		[Flags]
+		[CCode (cname = "tcpflags_t", cprefix = "TF_", has_type_id = false)]
+		public enum Flags {
+			ACK_DELAY,
+			ACK_NOW,
+			INFR,
+			CLOSEPEND,
+			RXCLOSED,
+			FIN,
+			NODELAY,
+			NAGLEMEMERR,
+			WND_SCALE,
+			BACKLOGPEND,
+			TIMESTAMP,
+			RTO,
+			SACK,
+		}
+
 		[Flags]
 		[CCode (cname = "u8_t", cprefix = "TCP_WRITE_FLAG_", has_type_id = false)]
 		public enum WriteFlags {