Fixes #982

Author: d2weber

src/socket/tcp.rs

@@ -486,6 +486,7 @@ impl<'a> Socket<'a> {
         // [...] the above constraints imply that 2 * the max window size must be less
         // than 2**31 [...] Thus, the shift count must be limited to 14 (which allows
         // windows of 2**30 = 1 Gbyte).
+        #[cfg(not(target_pointer_width = "16"))] // Prevent overflow
         if rx_capacity > (1 << 30) {
             panic!("receiving buffer too large, cannot exceed 1 GiB")
         }
@@ -594,7 +595,7 @@ impl<'a> Socket<'a> {
     fn scaled_window(&self) -> u16 {
         cmp::min(
             self.rx_buffer.window() >> self.remote_win_shift as usize,
-            (1 << 16) - 1,
+            u16::MAX as usize,
         ) as u16
     }
 
@@ -1868,7 +1869,10 @@ impl<'a> Socket<'a> {
         let assembler_was_empty = self.assembler.is_empty();
 
         // Try adding payload octets to the assembler.
-        let Ok(contig_len) = self.assembler.add_then_remove_front(payload_offset, payload_len) else {
+        let Ok(contig_len) = self
+            .assembler
+            .add_then_remove_front(payload_offset, payload_len)
+        else {
             net_debug!(
                 "assembler: too many holes to add {} octets at offset {}",
                 payload_len,
@@ -2155,7 +2159,7 @@ impl<'a> Socket<'a> {
             State::SynSent | State::SynReceived => {
                 repr.control = TcpControl::Syn;
                 // window len must NOT be scaled in SYNs.
-                repr.window_len = self.rx_buffer.window().min((1 << 16) - 1) as u16;
+                repr.window_len = u16::try_from(self.rx_buffer.window()).unwrap_or(u16::MAX);
                 if self.state == State::SynSent {
                     repr.ack_number = None;
                     repr.window_scale = Some(self.remote_win_shift);