implement the recvmsg handler for udp

netstack/src/scheme/udp.rs

@@ -12,6 +12,7 @@ use super::{parse_endpoint, SchemeWrapper, Smolnetd, SocketSet};
 use crate::port_set::PortSet;
 use crate::router::Router;
 use std::fmt::Write;
+use libredox::flag;
 
 const SO_SNDBUF: usize = 7;
 const SO_RCVBUF: usize = 8;
@@ -59,7 +60,7 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
 
                     if !is_broadcast && !connected_addr.is_unspecified() {
                         if source.addr != connected_addr || source.port != data.port {
-                            // Bad packet detetced
+                            // Bad packet detected
                             // Remove it from the buffer immediately so poll() doesn't trigger
                             let _ = self.recv();
                             continue; // Loop again to check the next packet
@@ -297,9 +298,57 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
     }
 
     fn handle_recvmsg(&mut self, file: &mut SchemeFile<Self>, how:&mut [u8], flags:usize) -> SyscallResult<usize> {
-        return Err(SyscallError::new(syscall::EOPNOTSUPP));
+        //there is a separate flags argument for MSG_DONTWAIT which is call specific not socket-wide like socket_file.flags
+        let socket_file = match file{
+            SchemeFile::Socket(ref mut sock_f) => sock_f,
+            _ => return Err(SyscallError::new(syscall::EBADF))
+        };
+
+        if !socket_file.read_enabled {
+            Ok(0)
+        } else if self.can_recv(&socket_file.data) {
+            let usize_length = core::mem::size_of::<usize>();
+            let prepared_name_len = usize::from_le_bytes(
+                how[0..usize_length].try_into().map_err(|_| SyscallError::new(syscall::EINVAL))?,
+            );
+            let prepared_whole_iov_size = usize::from_le_bytes(
+                how[usize_length..2 * usize_length].try_into().map_err(|_| SyscallError::new(syscall::EINVAL))?,
+            );
+            let prepared_msg_controllen = usize::from_le_bytes(
+                how[2 * usize_length..3 * usize_length].try_into().map_err(|_| SyscallError::new(syscall::EINVAL))?,
+            );
+            if  prepared_name_len + prepared_msg_controllen + prepared_whole_iov_size > how.len() {//expected returned buffer size is larger than provided -> return invalid
+                return Err(SyscallError::new(syscall::EINVAL));
+            }
+           
+            //the relibc deserialization functions expect NO GAPS between the name and payload slices
+            //so the payload must be temporarily stored during recv_slice
+            let mut payload_tmp = vec![0u8; prepared_whole_iov_size - prepared_name_len]; 
+            let (length, address) = self.recv_slice(&mut payload_tmp).expect("Can't recieve slice");
+            
+            //Address Handling
+            let address_formatted = if prepared_name_len > 0 {
+                format!("/scheme/udp/{}:{}", address.endpoint.addr, address.endpoint.port)
+            } else {
+                String::from("")
+            };
+            how[..usize_length].copy_from_slice(&address_formatted.len().to_le_bytes());
+            let payload_len_index = address_formatted.len() + usize_length;
+            how[usize_length..payload_len_index].copy_from_slice(&address_formatted.as_bytes());
+
+            //Payload Handling
+            how[payload_len_index..payload_len_index + usize_length].copy_from_slice(&(length as usize).to_le_bytes());
+            how[payload_len_index + usize_length..payload_len_index + usize_length + length].copy_from_slice(&payload_tmp[..length]);
+            //TODO should return the length of payload but relibc uses trim on the buffer incorrectly
+            Ok(how.len())
+        } else if socket_file.flags & syscall::O_NONBLOCK == syscall::O_NONBLOCK || flags & flag::MSG_DONTWAIT as usize != 0 {
+            Err(SyscallError::new(syscall::EAGAIN))
+        } else {
+            Err(SyscallError::new(syscall::EWOULDBLOCK)) // internally scheduled to re-read
+        }
     }
 
+
     fn handle_get_peer_name(
         &self,
         file: &SchemeFile<Self>,