Set TCP_USER_TIMEOUT socket option

src/core/lib/iomgr/socket_utils_common_posix.cc

@@ -222,6 +222,30 @@ grpc_error* grpc_set_socket_low_latency(int fd, int low_latency) {
   return GRPC_ERROR_NONE;
 }
 
+#define DEFAULT_TCP_USER_TIMEOUT 20000 /* 20 seconds */
+
+/* Set TCP_USER_TIMEOUT */
+grpc_error* grpc_set_socket_tcp_user_timeout(int fd, int val) {
+#ifdef GPR_LINUX
+  int newval;
+  socklen_t len;
+  if (val == 0) {
+    val = DEFAULT_TCP_USER_TIMEOUT;
+  }
+  if (0 != setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT, &val, sizeof(val))) {
+    return GRPC_OS_ERROR(errno, "setsockopt(TCP_USER_TIMEOUT)");
+  }
+  if (0 != getsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT, &newval, &len)) {
+    return GRPC_OS_ERROR(errno, "getsockopt(TCP_USER_TIMEOUT)");
+  }
+  if (newval != val) {
+    return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+        "Failed to set TCP_USER_TIMEOUT");
+  }
+#endif /* GPR_LINUX */
+  return GRPC_ERROR_NONE;
+}
+
 /* set a socket using a grpc_socket_mutator */
 grpc_error* grpc_set_socket_with_mutator(int fd, grpc_socket_mutator* mutator) {
   GPR_ASSERT(mutator);

src/core/lib/iomgr/socket_utils_posix.h

@@ -53,6 +53,9 @@ grpc_error* grpc_set_socket_low_latency(int fd, int low_latency);
 /* set SO_REUSEPORT */
 grpc_error* grpc_set_socket_reuse_port(int fd, int reuse);
 
+/* Set TCP_USER_TIMEOUT to val, or the default value if val is 0. */
+grpc_error* grpc_set_socket_tcp_user_timeout(int fd, int val);
+
 /* Returns true if this system can create AF_INET6 sockets bound to ::1.
    The value is probed once, and cached for the life of the process.
 

src/core/lib/iomgr/tcp_client_posix.cc

@@ -76,8 +76,11 @@ static grpc_error* prepare_socket(const grpc_resolved_address* addr, int fd,
   if (!grpc_is_unix_socket(addr)) {
     err = grpc_set_socket_low_latency(fd, 1);
     if (err != GRPC_ERROR_NONE) goto error;
+    err = grpc_set_socket_tcp_user_timeout(fd, 0 /* set to gRPC default */);
+    if (err != GRPC_ERROR_NONE) goto error;
   }
   err = grpc_set_socket_no_sigpipe_if_possible(fd);
+
   if (err != GRPC_ERROR_NONE) goto error;
   if (channel_args) {
     for (size_t i = 0; i < channel_args->num_args; i++) {

src/core/lib/iomgr/tcp_server_utils_posix_common.cc

@@ -166,6 +166,8 @@ grpc_error* grpc_tcp_server_prepare_socket(grpc_tcp_server* s, int fd,
     if (err != GRPC_ERROR_NONE) goto error;
     err = grpc_set_socket_reuse_addr(fd, 1);
     if (err != GRPC_ERROR_NONE) goto error;
+    err = grpc_set_socket_tcp_user_timeout(fd, 0);
+    if (err != GRPC_ERROR_NONE) goto error;
   }
   err = grpc_set_socket_no_sigpipe_if_possible(fd);
   if (err != GRPC_ERROR_NONE) goto error;