[PATCH v3] Define SO_RCVTIMEO and SO_SNDTIMEO.

[Christopher Baines]

These are important for reliable networking, since they prevent network
operations from hanging indefinitely.

* libguile/socket.c (scm_init_socket): Define SO_RCVTIMEO and
SO_SNDTIMEO.
(scm_getsockopt, scm_setsockopt): Include SO_RCVTIMEO and SO_SNDTIMEO in
docstring and handle them.
* doc/ref/posix.texi (Network Sockets and Communication): Document them.
---
 doc/ref/posix.texi |  2 ++
 libguile/socket.c  | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/doc/ref/posix.texi b/doc/ref/posix.texi
index 19911a427..5c7dce90d 100644
--- a/doc/ref/posix.texi
+++ b/doc/ref/posix.texi
@@ -3229,6 +3229,8 @@ Manual}, or @command{man 7 socket}.
 @defvarx SO_NO_CHECK
 @defvarx SO_PRIORITY
 @defvarx SO_REUSEPORT
+@defvarx SO_RCVTIMEO
+@defvarx SO_SNDTIMEO
 The @var{value} taken or returned is an integer.
 @end defvar
 
diff --git a/libguile/socket.c b/libguile/socket.c
index b3482c8f3..8451aadac 100644
--- a/libguile/socket.c
+++ b/libguile/socket.c
@@ -35,6 +35,7 @@
 #endif
 #include <unistd.h>
 #include <sys/types.h>
+#include <sys/time.h>
 
 #ifdef HAVE_WINSOCK2_H
 #include <winsock2.h>
@@ -502,6 +503,12 @@ SCM_DEFINE (scm_getsockopt, "getsockopt", 3, 0, 0,
            "timeout support (ie.@: without @code{struct linger}), only\n"
            "@var{enable} has an effect but the value in Guile is always a\n"
            "pair.\n"
+           "@end defvar"
+            "\n"
+           "@defvar SO_RCVTIMEO\n"
+           "@defvarx SO_SNDTIMEO\n"
+           "@var{value} is a pair of integers @code{(@var{SECONDS}\n"
+           ". @var{MICROSECONDS})}.\n"
            "@end defvar")
 #define FUNC_NAME s_scm_getsockopt
 {
@@ -522,6 +529,16 @@ SCM_DEFINE (scm_getsockopt, "getsockopt", 3, 0, 0,
   if (getsockopt (fd, ilevel, ioptname, (void *) &optval, &optlen) == -1)
     SCM_SYSERROR;
 
+#if defined(SO_RCVTIMEO) && defined(SO_SNDTIMEO)
+  if (ioptname == SO_RCVTIMEO || ioptname == SO_SNDTIMEO)
+    {
+      struct timeval *opt_time = (struct timeval *) &optval;
+
+      return scm_cons (scm_from_long (opt_time->tv_sec),
+                       scm_from_long (opt_time->tv_usec));
+    }
+#endif
+
   if (ilevel == SOL_SOCKET)
     {
 #ifdef SO_LINGER
@@ -590,6 +607,12 @@ SCM_DEFINE (scm_setsockopt, "setsockopt", 4, 0, 0,
            "(ie.@: without @code{struct linger}), only @var{ENABLE} has an\n"
            "effect but the value in Guile is always a pair.\n"
            "@end defvar\n"
+            "\n"
+           "@defvar SO_RCVTIMEO\n"
+           "@defvarx SO_SNDTIMEO\n"
+           "@var{value} is a pair of integers @code{(@var{SECONDS}\n"
+           ". @var{MICROSECONDS})}.\n"
+           "@end defvar\n"
            "\n"
            "@c  Note that we refer only to ``man ip'' here.  On GNU/Linux 
it's\n"
            "@c  ``man 7 ip'' but on NetBSD it's ``man 4 ip''.\n"
@@ -633,6 +656,8 @@ SCM_DEFINE (scm_setsockopt, "setsockopt", 4, 0, 0,
   struct ip_mreq opt_mreq;
 #endif
 
+  struct timeval opt_time;
+
   const void *optval = NULL;
   socklen_t optlen = 0;
 
@@ -682,6 +707,19 @@ SCM_DEFINE (scm_setsockopt, "setsockopt", 4, 0, 0,
     }
 #endif
 
+#if defined(SO_RCVTIMEO) && defined(SO_SNDTIMEO)
+  if (ioptname == SO_RCVTIMEO || ioptname == SO_SNDTIMEO)
+    {
+      SCM_ASSERT_TYPE (scm_is_pair (value), value, SCM_ARG4, FUNC_NAME,
+                       "value");
+      opt_time.tv_sec = scm_to_ulong (SCM_CAR (value));
+      opt_time.tv_usec = scm_to_ulong (SCM_CDR (value));
+
+      optlen = sizeof (opt_time);
+      optval = &opt_time;
+    }
+#endif
+
   if (optval == NULL)
     {
       /* Most options take an int.  */
@@ -1768,6 +1806,12 @@ scm_init_socket ()
 #ifdef SO_REUSEPORT                              /* new in Linux 3.9 */
   scm_c_define ("SO_REUSEPORT", scm_from_int (SO_REUSEPORT));
 #endif
+#ifdef SO_RCVTIMEO
+  scm_c_define ("SO_RCVTIMEO", scm_from_int (SO_RCVTIMEO));
+#endif
+#ifdef SO_SNDTIMEO
+  scm_c_define ("SO_SNDTIMEO", scm_from_int (SO_SNDTIMEO));
+#endif
 
   /* recv/send options.  */
 #ifdef MSG_DONTWAIT
-- 
2.37.3