From 0e2cd38135166d64dbf1bdd2d771ac138882a4df Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Tue, 4 Oct 2016 06:40:38 +0000
Subject: [PATCH] Rust: set the SOF_KEEPALIVE flag on session sockets.

---
 artiq/runtime.rs/liblwip-sys/lib.rs |  5 +++++
 artiq/runtime.rs/liblwip/lib.rs     | 12 ++++++++++++
 artiq/runtime.rs/src/sched.rs       |  8 ++++++++
 artiq/runtime.rs/src/session.rs     |  1 +
 artiq/runtime/main.c                |  4 ++++
 5 files changed, 30 insertions(+)

diff --git a/artiq/runtime.rs/liblwip-sys/lib.rs b/artiq/runtime.rs/liblwip-sys/lib.rs
index 5ea2e7d1e..82a7c5bcf 100644
--- a/artiq/runtime.rs/liblwip-sys/lib.rs
+++ b/artiq/runtime.rs/liblwip-sys/lib.rs
@@ -103,6 +103,10 @@ pub struct udp_pcb {
 pub const TCP_WRITE_FLAG_COPY: u8 = 0x01;
 pub const TCP_WRITE_FLAG_MORE: u8 = 0x02;
 
+pub const SOF_REUSEADDR: u8 = 0x04;
+pub const SOF_KEEPALIVE: u8 = 0x08;
+pub const SOF_BROADCAST: u8 = 0x20;
+
 extern {
     pub fn pbuf_alloc(l: pbuf_layer, length: u16, type_: pbuf_type) -> *mut pbuf;
     pub fn pbuf_realloc(p: *mut pbuf, length: u16);
@@ -144,6 +148,7 @@ extern {
 
     // nonstandard
     pub fn tcp_sndbuf_(pcb: *mut tcp_pcb) -> u16;
+    pub fn tcp_so_options_(pcb: *mut tcp_pcb) -> *mut u8;
 
     pub fn udp_new() -> *mut udp_pcb;
     pub fn udp_new_ip_type(type_: ip_addr_type) -> *mut udp_pcb;
diff --git a/artiq/runtime.rs/liblwip/lib.rs b/artiq/runtime.rs/liblwip/lib.rs
index c996074f0..4a6e1b3c1 100644
--- a/artiq/runtime.rs/liblwip/lib.rs
+++ b/artiq/runtime.rs/liblwip/lib.rs
@@ -397,6 +397,18 @@ impl TcpListener {
     pub fn try_accept(&self) -> Option<TcpStream> {
         self.state.borrow_mut().backlog.pop_front()
     }
+
+    pub fn keepalive(&self) -> bool {
+        unsafe { *lwip_sys::tcp_so_options_(self.raw) & lwip_sys::SOF_KEEPALIVE != 0 }
+    }
+
+    pub fn set_keepalive(&self, keepalive: bool) {
+        if keepalive {
+            unsafe { *lwip_sys::tcp_so_options_(self.raw) |= lwip_sys::SOF_KEEPALIVE }
+        } else {
+            unsafe { *lwip_sys::tcp_so_options_(self.raw) &= !lwip_sys::SOF_KEEPALIVE }
+        }
+    }
 }
 
 impl Drop for TcpListener {
diff --git a/artiq/runtime.rs/src/sched.rs b/artiq/runtime.rs/src/sched.rs
index 34dd5bc8c..4737ee0c6 100644
--- a/artiq/runtime.rs/src/sched.rs
+++ b/artiq/runtime.rs/src/sched.rs
@@ -391,6 +391,14 @@ impl<'a> TcpListener<'a> {
     pub fn acceptable(&self) -> bool {
         self.lower.state().borrow().acceptable()
     }
+
+    pub fn keepalive(&self) -> bool {
+        self.lower.keepalive()
+    }
+
+    pub fn set_keepalive(&self, keepalive: bool) {
+        self.lower.set_keepalive(keepalive)
+    }
 }
 
 pub use lwip::Shutdown;
diff --git a/artiq/runtime.rs/src/session.rs b/artiq/runtime.rs/src/session.rs
index e4fdf2924..879ad159d 100644
--- a/artiq/runtime.rs/src/session.rs
+++ b/artiq/runtime.rs/src/session.rs
@@ -396,6 +396,7 @@ pub fn thread(waiter: Waiter, spawner: Spawner) {
 
     let addr = SocketAddr::new(IP_ANY, 1381);
     let listener = TcpListener::bind(waiter, addr).expect("cannot bind socket");
+    listener.set_keepalive(true);
     info!("accepting network sessions in Rust");
 
     let mut kernel_thread = None;
diff --git a/artiq/runtime/main.c b/artiq/runtime/main.c
index c2460b32a..bf1091526 100644
--- a/artiq/runtime/main.c
+++ b/artiq/runtime/main.c
@@ -237,6 +237,10 @@ u16_t tcp_sndbuf_(struct tcp_pcb *pcb) {
     return tcp_sndbuf(pcb);
 }
 
+u8_t* tcp_so_options_(struct tcp_pcb *pcb) {
+    return &pcb->so_options;
+}
+
 int main(void)
 {
     irq_setmask(0);