add tcp support and tcp_simplehttp app

os/src/syscall/net.rs

@@ -1,7 +1,8 @@
-use alloc::sync::Arc;
-use crate::net::IPv4;
+use crate::net::port_table::{listen, PortFd, accept, port_acceptable};
 use crate::net::udp::UDP;
-use crate::task::current_process;
+use crate::net::{IPv4, net_interrupt_handler};
+use crate::task::{current_process, block_current_and_run_next, current_task, current_trap_cx};
+use alloc::sync::Arc;
 
 // just support udp
 pub fn sys_connect(raddr: u32, lport: u16, rport: u16) -> isize {
@@ -10,5 +11,43 @@ pub fn sys_connect(raddr: u32, lport: u16, rport: u16) -> isize {
     let fd = inner.alloc_fd();
     let udp_node = UDP::new(IPv4::from_u32(raddr), lport, rport);
     inner.fd_table[fd] = Some(Arc::new(udp_node));
-    fd as isize    
-}
+    fd as isize
+}
+
+// listen a port
+pub fn sys_listen(port: u16) -> isize {
+    match listen(port) {
+        Some(port_index) => {
+            let process = current_process();
+            let mut inner = process.inner_exclusive_access();
+            let fd = inner.alloc_fd();
+            let port_fd = PortFd::new(port_index);
+            inner.fd_table[fd] = Some(Arc::new(port_fd));
+
+            // NOTICE: this return the port index, not the fd
+            port_index as isize
+        }
+        None => -1,
+    }
+}
+
+// accept a tcp connection
+pub fn sys_accept(port_index: usize) -> isize {
+    println!("accepting port {}", port_index);
+    
+    let task = current_task().unwrap();
+    accept(port_index, task);
+    // block_current_and_run_next();
+    
+    // NOTICE: There does not have interrupt handler, just call it munually.
+    loop {
+        net_interrupt_handler();
+
+        if !port_acceptable(port_index) {
+            break;
+        }
+    }
+
+    let cx = current_trap_cx();
+    cx.x[10] as isize
+}