Refactor ping timeout tracking

src/lib.rs

@@ -54,6 +54,7 @@ mod packet;
 mod ping;
 
 pub use crate::errors::Error;
+#[allow(deprecated)]
 pub use crate::ping::{
     Ping, PingResult, SocketType, SocketType::DGRAM, SocketType::RAW, dgramsock, new, ping, rawsock,
 };

src/ping.rs

@@ -1,5 +1,5 @@
 use std::net::{IpAddr, SocketAddr};
-use std::time::{Duration, SystemTime};
+use std::time::{Duration, Instant};
 
 use rand::random;
 use socket2::{Domain, Protocol, Socket, Type};
@@ -11,6 +11,12 @@ const TOKEN_SIZE: usize = 24;
 const ECHO_REQUEST_BUFFER_SIZE: usize = ICMP_HEADER_SIZE + TOKEN_SIZE;
 type Token = [u8; TOKEN_SIZE];
 
+fn remaining_timeout(started_at: Instant, timeout: Duration) -> std::io::Result<Duration> {
+    timeout
+        .checked_sub(started_at.elapsed())
+        .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::TimedOut, "ping request timed out"))
+}
+
 /// The kind of socket used to send the ICMP request.
 ///
 /// The default depends on the platform. On Windows [`Ping::new`] uses
@@ -75,8 +81,6 @@ fn ping_with_socktype(
     payload: Option<&Token>,
     bind_device: Option<&str>,
 ) -> Result<PingResult, Error> {
-    let time_start = SystemTime::now();
-
     let timeout = match timeout {
         Some(timeout) => timeout,
         None => Duration::from_secs(4),
@@ -125,12 +129,12 @@ fn ping_with_socktype(
 
     socket.set_write_timeout(Some(timeout))?;
 
+    let started_at = Instant::now();
     socket.send_to(&mut buffer, &dest.into())?;
 
     // loop until either an echo whose payload token matches was received or timeout is over
-    let mut elapsed_time = Duration::from_secs(0);
     loop {
-        socket.set_read_timeout(Some(timeout - elapsed_time))?;
+        socket.set_read_timeout(Some(remaining_timeout(started_at, timeout)?))?;
 
         let mut buffer: [u8; 2048] = [0; 2048];
         // socket2 0.6 recv_from requires &mut [MaybeUninit<u8>]; cast is sound
@@ -172,16 +176,10 @@ fn ping_with_socktype(
             }
         };
 
-        // update elapsed time before deciding whether the payload token matches
-        elapsed_time = match SystemTime::now().duration_since(time_start) {
-            Ok(reply) => reply,
-            Err(_) => return Err(Error::InternalError.into()),
-        };
-
         if reply.payload == request.payload {
             // payload token matched: this reply belongs to our request
             return Ok(PingResult {
-                rtt: elapsed_time,
+                rtt: started_at.elapsed(),
                 ident: reply.ident,
                 seq_cnt: reply.seq_cnt,
                 payload: reply.payload.to_vec(),
@@ -190,11 +188,6 @@ fn ping_with_socktype(
                 ttl: recv_ttl,
             });
         }
-
-        if elapsed_time >= timeout {
-            let error = std::io::Error::new(std::io::ErrorKind::TimedOut, "Timeout occured");
-            return Err(Error::IoError { error: (error) });
-        }
     }
 }
 
@@ -237,6 +230,7 @@ pub mod dgramsock {
     }
 }
 
+#[deprecated(since = "0.8.0", note = "use `Ping::new` builder and `Ping::send` instead")]
 pub fn ping(
     addr: IpAddr,
     timeout: Option<Duration>,