Add capacity methods to all sockets.

src/socket/icmp.rs

@@ -189,6 +189,30 @@ impl<'a, 'b> IcmpSocket<'a, 'b> {
         !self.rx_buffer.is_empty()
     }
 
+    /// Return the maximum number packets the socket can receive.
+    #[inline]
+    pub fn packet_recv_capacity(&self) -> usize {
+        self.rx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number packets the socket can transmit.
+    #[inline]
+    pub fn packet_send_capacity(&self) -> usize {
+        self.tx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the recv buffer.
+    #[inline]
+    pub fn payload_recv_capacity(&self) -> usize {
+        self.rx_buffer.payload_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the transmit buffer.
+    #[inline]
+    pub fn payload_send_capacity(&self) -> usize {
+        self.tx_buffer.payload_capacity()
+    }
+
     /// Check whether the socket is open.
     #[inline]
     pub fn is_open(&self) -> bool {

src/socket/raw.rs

@@ -74,6 +74,30 @@ impl<'a, 'b> RawSocket<'a, 'b> {
         !self.rx_buffer.is_empty()
     }
 
+    /// Return the maximum number packets the socket can receive.
+    #[inline]
+    pub fn packet_recv_capacity(&self) -> usize {
+        self.rx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number packets the socket can transmit.
+    #[inline]
+    pub fn packet_send_capacity(&self) -> usize {
+        self.tx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the recv buffer.
+    #[inline]
+    pub fn payload_recv_capacity(&self) -> usize {
+        self.rx_buffer.payload_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the transmit buffer.
+    #[inline]
+    pub fn payload_send_capacity(&self) -> usize {
+        self.tx_buffer.payload_capacity()
+    }
+
     /// Enqueue a packet to send, and return a pointer to its payload.
     ///
     /// This function returns `Err(Error::Exhausted)` if the transmit buffer is full,

src/socket/tcp.rs

@@ -640,6 +640,18 @@ impl<'a> TcpSocket<'a> {
         !self.tx_buffer.is_full()
     }
 
+    /// Return the maximum number of bytes inside the recv buffer.
+    #[inline]
+    pub fn recv_capacity(&self) -> usize {
+        self.rx_buffer.capacity()
+    }
+
+    /// Return the maximum number of bytes inside the transmit buffer.
+    #[inline]
+    pub fn send_capacity(&self) -> usize {
+        self.tx_buffer.capacity()
+    }
+
     /// Check whether the receive half of the full-duplex connection buffer is open
     /// (see [may_recv](#method.may_recv), and the receive buffer is not empty.
     #[inline]

src/socket/udp.rs

@@ -110,6 +110,30 @@ impl<'a, 'b> UdpSocket<'a, 'b> {
         !self.rx_buffer.is_empty()
     }
 
+    /// Return the maximum number packets the socket can receive.
+    #[inline]
+    pub fn packet_recv_capacity(&self) -> usize {
+        self.rx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number packets the socket can transmit.
+    #[inline]
+    pub fn packet_send_capacity(&self) -> usize {
+        self.tx_buffer.packet_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the recv buffer.
+    #[inline]
+    pub fn payload_recv_capacity(&self) -> usize {
+        self.rx_buffer.payload_capacity()
+    }
+
+    /// Return the maximum number of bytes inside the transmit buffer.
+    #[inline]
+    pub fn payload_send_capacity(&self) -> usize {
+        self.tx_buffer.payload_capacity()
+    }
+
     /// Enqueue a packet to be sent to a given remote endpoint, and return a pointer
     /// to its payload.
     ///

src/storage/packet_buffer.rs

@@ -168,6 +168,16 @@ impl<'a, 'b, H> PacketBuffer<'a, 'b, H> {
             Err(Error::Exhausted)
         }
     }
+
+    /// Return the maximum number packets that can be stored.
+    pub fn packet_capacity(&self) -> usize {
+        self.metadata_ring.capacity()
+    }
+
+    /// Return the maximum number of bytes in the payload ring buffer.
+    pub fn payload_capacity(&self) -> usize {
+        self.payload_ring.capacity()
+    }
 }
 
 #[cfg(test)]