From badaa83c319ae5a0bef872d1e7a55bf1260c1b84 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Wed, 18 Jan 2023 16:14:10 +0100
Subject: [PATCH] refclock: convert mismatched timeval in SOCK messages

On 32-bit glibc-based (>=2.34) systems, allow the SOCK client to send
messages with timevals using the other time_t size than chrony. If the
length of the received message corresponds to the other size, convert
the timeval and move the rest of the message before its processing.

This is needed for compatibility with the current development version of
gpsd, which forces 64-bit time_t on these systems, while chrony needs to
be compiled with the same time_t as gnutls.
---
 refclock_sock.c | 42 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/refclock_sock.c b/refclock_sock.c
index f0d91c5..2302b9d 100644
--- a/refclock_sock.c
+++ b/refclock_sock.c
@@ -58,8 +58,27 @@ struct sock_sample {
   int magic;
 };
 
+/* On 32-bit glibc-based systems enable conversion between timevals using
+   32-bit and 64-bit time_t to support SOCK clients compiled with different
+   time_t size than chrony */
+#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 34) && __TIMESIZE == 32
+#define CONVERT_TIMEVAL 1
+#if defined(_TIME_BITS) && _TIME_BITS == 64
+typedef int32_t alt_time_t;
+typedef int32_t alt_suseconds_t;
+#else
+typedef int64_t alt_time_t;
+typedef int64_t alt_suseconds_t;
+#endif
+struct alt_timeval {
+  alt_time_t tv_sec;
+  alt_suseconds_t tv_usec;
+};
+#endif
+
 static void read_sample(int sockfd, int event, void *anything)
 {
+  char buf[sizeof (struct sock_sample) + 16];
   struct timespec sys_ts, ref_ts;
   struct sock_sample sample;
   RCL_Instance instance;
@@ -67,14 +86,33 @@ static void read_sample(int sockfd, int event, void *anything)
 
   instance = (RCL_Instance)anything;
 
-  s = recv(sockfd, &sample, sizeof (sample), 0);
+  s = recv(sockfd, buf, sizeof (buf), 0);
 
   if (s < 0) {
     DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
     return;
   }
 
-  if (s != sizeof (sample)) {
+  if (s == sizeof (sample)) {
+    memcpy(&sample, buf, sizeof (sample));
+#ifdef CONVERT_TIMEVAL
+  } else if (s == sizeof (sample) - sizeof (struct timeval) + sizeof (struct alt_timeval)) {
+    struct alt_timeval atv;
+    memcpy(&atv, buf, sizeof (atv));
+#ifndef HAVE_LONG_TIME_T
+    if (atv.tv_sec > INT32_MAX || atv.tv_sec < INT32_MIN ||
+        atv.tv_usec > INT32_MAX || atv.tv_usec < INT32_MIN) {
+      DEBUG_LOG("Could not convert 64-bit timeval");
+      return;
+    }
+#endif
+    sample.tv.tv_sec = atv.tv_sec;
+    sample.tv.tv_usec = atv.tv_usec;
+    DEBUG_LOG("Converted %u-bit timeval", 8 * sizeof (alt_time_t));
+    memcpy((char *)&sample + sizeof (struct timeval), buf + sizeof (struct alt_timeval),
+           sizeof (sample) - sizeof (struct timeval));
+#endif
+  } else {
     DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
               s, (long)sizeof (sample));
     return;