From 2cf5adccf82f1fbbcee8f06c8877dd5dd5c57354 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 4 Dec 2025 11:39:30 -0500
Subject: [PATCH 01/27] Add failing test

---
 src/libmongoc/tests/test-mongoc-client.c | 41 ++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index 04ba91a023e..7bc0447fec2 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3836,6 +3836,46 @@ test_killCursors(void)
    mongoc_client_destroy(client);
 }
 
+static void
+test_socketTimeoutMS_zero(void)
+{
+   mongoc_uri_t *const uri = test_framework_get_uri();
+   mongoc_uri_set_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, 0);
+
+   mongoc_client_t *const client = test_framework_client_new_from_uri(uri, NULL);
+
+   // Configure a failpoint to block on "ping" for 500ms.
+   bson_error_t error;
+   bool ok = mongoc_client_command_simple(
+      client,
+      "admin",
+      tmp_bson(BSON_STR({
+         "configureFailPoint" : "failCommand",
+         "mode" : {"times" : 1},
+         "data" : {"failCommands" : ["ping"], "blockTimeMS" : 500, "blockConnection" : true}
+      })),
+      NULL,
+      NULL,
+      &error);
+   ASSERT_OR_PRINT(ok, error);
+
+   // Expect "ping" to take 500ms.
+   const mlib_time_point start = mlib_now();
+
+   // Send "ping":
+   ok = mongoc_client_command_simple(client, "admin", tmp_bson(BSON_STR({"ping" : 1})), NULL, NULL, &error);
+   ASSERT_OR_PRINT(ok, error);
+
+   const mlib_time_point end = mlib_now();
+
+   const mlib_duration elapsed = mlib_time_difference(end, start);
+
+   ASSERT_CMPINT64(mlib_microseconds_count(elapsed), >=, mlib_microseconds_count(mlib_duration(500, ms)));
+
+   mongoc_client_destroy(client);
+   mongoc_uri_destroy(uri);
+}
+
 void
 test_client_install(TestSuite *suite)
 {
@@ -4051,4 +4091,5 @@ test_client_install(TestSuite *suite)
                      test_framework_skip_if_no_server_ssl);
 #endif
    TestSuite_AddLive(suite, "/Client/killCursors", test_killCursors);
+   TestSuite_AddLive(suite, "/Client/socketTimeoutMS_zero", test_socketTimeoutMS_zero);
 }

From 6ed9323d7615bdebe9b5cba071168b5bc4b8ce6c Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 4 Dec 2025 11:40:17 -0500
Subject: [PATCH 02/27] Fix socketTimeoutMS=0 ignored in URI

---
 src/libmongoc/src/mongoc/mongoc-client.h      | 13 ----------
 src/libmongoc/src/mongoc/mongoc-cluster.c     |  3 +--
 src/libmongoc/src/mongoc/mongoc-uri-private.h |  3 +++
 src/libmongoc/src/mongoc/mongoc-uri.c         | 25 ++++++++++++++-----
 src/libmongoc/src/mongoc/mongoc-uri.h         | 12 +++++++++
 5 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-client.h b/src/libmongoc/src/mongoc/mongoc-client.h
index 2b53c91b8b0..3c89c0e70a4 100644
--- a/src/libmongoc/src/mongoc/mongoc-client.h
+++ b/src/libmongoc/src/mongoc/mongoc-client.h
@@ -54,19 +54,6 @@ BSON_BEGIN_DECLS
 #endif
 
 
-#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
-/*
- * NOTE: The default socket timeout for connections is 5 minutes. This
- *       means that if your MongoDB server dies or becomes unavailable
- *       it will take 5 minutes to detect this.
- *
- *       You can change this by providing sockettimeoutms= in your
- *       connection URI.
- */
-#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
-#endif
-
-
 /**
  * mongoc_client_t:
  *
diff --git a/src/libmongoc/src/mongoc/mongoc-cluster.c b/src/libmongoc/src/mongoc/mongoc-cluster.c
index 0519ec0a179..3a2e6171f58 100644
--- a/src/libmongoc/src/mongoc/mongoc-cluster.c
+++ b/src/libmongoc/src/mongoc/mongoc-cluster.c
@@ -2502,8 +2502,7 @@ void
 mongoc_cluster_reset_sockettimeoutms(mongoc_cluster_t *cluster)
 {
    BSON_ASSERT_PARAM(cluster);
-   cluster->sockettimeoutms =
-      mongoc_uri_get_option_as_int32(cluster->uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+   cluster->sockettimeoutms = mongoc_uri_get_sockettimeoutms_option(cluster->uri);
 }
 
 static uint32_t
diff --git a/src/libmongoc/src/mongoc/mongoc-uri-private.h b/src/libmongoc/src/mongoc/mongoc-uri-private.h
index 5e9dc2ac38f..ae759ed0932 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri-private.h
@@ -55,6 +55,9 @@ _mongoc_uri_apply_query_string(mongoc_uri_t *uri, mstr_view options, bool from_d
 int32_t
 mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri);
 
+int32_t
+mongoc_uri_get_sockettimeoutms_option(const mongoc_uri_t *uri);
+
 bool
 _mongoc_uri_requires_auth_negotiation(const mongoc_uri_t *uri);
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index d444cfdfd2f..c9e77557ea4 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2573,27 +2573,40 @@ mongoc_uri_get_compressors(const mongoc_uri_t *uri)
 }
 
 
-/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
 int32_t
-mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri)
+_mongoc_uri_get_option_as_int32_0_is_valid(const mongoc_uri_t *uri, const char *option, int32_t fallback)
 {
    const bson_t *options;
    bson_iter_t iter;
-   int32_t retval = MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS;
+   int32_t retval = fallback;
 
-   if ((options = mongoc_uri_get_options(uri)) && bson_iter_init_find_case(&iter, options, "localthresholdms") &&
+   if ((options = mongoc_uri_get_options(uri)) && bson_iter_init_find_case(&iter, options, option) &&
        BSON_ITER_HOLDS_INT32(&iter)) {
       retval = bson_iter_int32(&iter);
 
       if (retval < 0) {
-         MONGOC_WARNING("Invalid localThresholdMS: %d", retval);
-         retval = MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS;
+         MONGOC_WARNING("Invalid %s: %d", option, retval);
+         retval = fallback;
       }
    }
 
    return retval;
 }
 
+/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
+int32_t
+mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri)
+{
+   return _mongoc_uri_get_option_as_int32_0_is_valid(
+      uri, MONGOC_URI_LOCALTHRESHOLDMS, MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS);
+}
+
+/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
+int32_t
+mongoc_uri_get_sockettimeoutms_option(const mongoc_uri_t *uri)
+{
+   return _mongoc_uri_get_option_as_int32_0_is_valid(uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+}
 
 const char *
 mongoc_uri_get_srv_hostname(const mongoc_uri_t *uri)
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.h b/src/libmongoc/src/mongoc/mongoc-uri.h
index ecf689d6ae7..c788a244014 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri.h
@@ -33,6 +33,18 @@
 #define MONGOC_DEFAULT_PORT 27017
 #endif
 
+#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
+/*
+ * NOTE: The default socket timeout for connections is 5 minutes. This
+ *       means that if your MongoDB server dies or becomes unavailable
+ *       it will take 5 minutes to detect this.
+ *
+ *       You can change this by providing sockettimeoutms= in your
+ *       connection URI.
+ */
+#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
+#endif
+
 #define MONGOC_URI_APPNAME "appname"
 #define MONGOC_URI_AUTHMECHANISM "authmechanism"
 #define MONGOC_URI_AUTHMECHANISMPROPERTIES "authmechanismproperties"

From 596727c96696b294c3984abc515c4c057ae351c7 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 4 Dec 2025 11:51:45 -0500
Subject: [PATCH 03/27] Treat 0 timeout as infinite

---
 src/libmongoc/src/mongoc/mongoc-stream-socket.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-socket.c b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
index 2c020f45170..9be3b3237af 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-socket.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
@@ -36,10 +36,8 @@ struct _mongoc_stream_socket_t {
 static BSON_INLINE int64_t
 get_expiration(int32_t timeout_msec)
 {
-   if (timeout_msec < 0) {
+   if (timeout_msec <= 0) {
       return -1;
-   } else if (timeout_msec == 0) {
-      return 0;
    } else {
       return (bson_get_monotonic_time() + ((int64_t)timeout_msec * 1000L));
    }

From 543260846557bfd03b8bec505ac483bc493920a6 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 4 Dec 2025 14:49:32 -0500
Subject: [PATCH 04/27] Fix meaning of 0 timeout for TLS

---
 src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
index 71bc8a1579b..9f84a56510b 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
@@ -121,7 +121,7 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
    ENTRY;
    BSON_ASSERT(secure_transport);
 
-   if (tls->timeout_msec >= 0) {
+   if (tls->timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000UL);
    }
 
@@ -300,7 +300,7 @@ _mongoc_stream_tls_secure_transport_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec >= 0) {
+   if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
    }
 

From bb23cbda1e7f12bbfe85806378f060b4cdd0457f Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 4 Dec 2025 15:04:57 -0500
Subject: [PATCH 05/27] Revert "Fix socketTimeoutMS=0 ignored in URI"

This reverts commit 6ed9323d7615bdebe9b5cba071168b5bc4b8ce6c.
---
 src/libmongoc/src/mongoc/mongoc-client.h      | 13 ++++++++++
 src/libmongoc/src/mongoc/mongoc-cluster.c     |  3 ++-
 src/libmongoc/src/mongoc/mongoc-uri-private.h |  3 ---
 src/libmongoc/src/mongoc/mongoc-uri.c         | 25 +++++--------------
 src/libmongoc/src/mongoc/mongoc-uri.h         | 12 ---------
 5 files changed, 21 insertions(+), 35 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-client.h b/src/libmongoc/src/mongoc/mongoc-client.h
index 3c89c0e70a4..2b53c91b8b0 100644
--- a/src/libmongoc/src/mongoc/mongoc-client.h
+++ b/src/libmongoc/src/mongoc/mongoc-client.h
@@ -54,6 +54,19 @@ BSON_BEGIN_DECLS
 #endif
 
 
+#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
+/*
+ * NOTE: The default socket timeout for connections is 5 minutes. This
+ *       means that if your MongoDB server dies or becomes unavailable
+ *       it will take 5 minutes to detect this.
+ *
+ *       You can change this by providing sockettimeoutms= in your
+ *       connection URI.
+ */
+#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
+#endif
+
+
 /**
  * mongoc_client_t:
  *
diff --git a/src/libmongoc/src/mongoc/mongoc-cluster.c b/src/libmongoc/src/mongoc/mongoc-cluster.c
index 3a2e6171f58..0519ec0a179 100644
--- a/src/libmongoc/src/mongoc/mongoc-cluster.c
+++ b/src/libmongoc/src/mongoc/mongoc-cluster.c
@@ -2502,7 +2502,8 @@ void
 mongoc_cluster_reset_sockettimeoutms(mongoc_cluster_t *cluster)
 {
    BSON_ASSERT_PARAM(cluster);
-   cluster->sockettimeoutms = mongoc_uri_get_sockettimeoutms_option(cluster->uri);
+   cluster->sockettimeoutms =
+      mongoc_uri_get_option_as_int32(cluster->uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
 }
 
 static uint32_t
diff --git a/src/libmongoc/src/mongoc/mongoc-uri-private.h b/src/libmongoc/src/mongoc/mongoc-uri-private.h
index ae759ed0932..5e9dc2ac38f 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri-private.h
@@ -55,9 +55,6 @@ _mongoc_uri_apply_query_string(mongoc_uri_t *uri, mstr_view options, bool from_d
 int32_t
 mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri);
 
-int32_t
-mongoc_uri_get_sockettimeoutms_option(const mongoc_uri_t *uri);
-
 bool
 _mongoc_uri_requires_auth_negotiation(const mongoc_uri_t *uri);
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index c9e77557ea4..d444cfdfd2f 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2573,40 +2573,27 @@ mongoc_uri_get_compressors(const mongoc_uri_t *uri)
 }
 
 
+/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
 int32_t
-_mongoc_uri_get_option_as_int32_0_is_valid(const mongoc_uri_t *uri, const char *option, int32_t fallback)
+mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri)
 {
    const bson_t *options;
    bson_iter_t iter;
-   int32_t retval = fallback;
+   int32_t retval = MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS;
 
-   if ((options = mongoc_uri_get_options(uri)) && bson_iter_init_find_case(&iter, options, option) &&
+   if ((options = mongoc_uri_get_options(uri)) && bson_iter_init_find_case(&iter, options, "localthresholdms") &&
        BSON_ITER_HOLDS_INT32(&iter)) {
       retval = bson_iter_int32(&iter);
 
       if (retval < 0) {
-         MONGOC_WARNING("Invalid %s: %d", option, retval);
-         retval = fallback;
+         MONGOC_WARNING("Invalid localThresholdMS: %d", retval);
+         retval = MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS;
       }
    }
 
    return retval;
 }
 
-/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
-int32_t
-mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri)
-{
-   return _mongoc_uri_get_option_as_int32_0_is_valid(
-      uri, MONGOC_URI_LOCALTHRESHOLDMS, MONGOC_TOPOLOGY_LOCAL_THRESHOLD_MS);
-}
-
-/* can't use mongoc_uri_get_option_as_int32, it treats 0 specially */
-int32_t
-mongoc_uri_get_sockettimeoutms_option(const mongoc_uri_t *uri)
-{
-   return _mongoc_uri_get_option_as_int32_0_is_valid(uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
-}
 
 const char *
 mongoc_uri_get_srv_hostname(const mongoc_uri_t *uri)
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.h b/src/libmongoc/src/mongoc/mongoc-uri.h
index c788a244014..ecf689d6ae7 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri.h
@@ -33,18 +33,6 @@
 #define MONGOC_DEFAULT_PORT 27017
 #endif
 
-#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
-/*
- * NOTE: The default socket timeout for connections is 5 minutes. This
- *       means that if your MongoDB server dies or becomes unavailable
- *       it will take 5 minutes to detect this.
- *
- *       You can change this by providing sockettimeoutms= in your
- *       connection URI.
- */
-#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
-#endif
-
 #define MONGOC_URI_APPNAME "appname"
 #define MONGOC_URI_AUTHMECHANISM "authmechanism"
 #define MONGOC_URI_AUTHMECHANISMPROPERTIES "authmechanismproperties"

From 5678eec14653229b7c90f92ec2d40a5d0ef397eb Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Mon, 8 Dec 2025 16:08:53 -0500
Subject: [PATCH 06/27] Support socketTimeoutMS=inf

---
 src/libmongoc/src/mongoc/mongoc-client.h      | 13 -----
 src/libmongoc/src/mongoc/mongoc-cluster.c     |  3 +-
 src/libmongoc/src/mongoc/mongoc-uri-private.h |  3 ++
 src/libmongoc/src/mongoc/mongoc-uri.c         | 23 ++++++++-
 src/libmongoc/src/mongoc/mongoc-uri.h         | 14 +++++
 src/libmongoc/tests/test-mongoc-client.c      |  6 +--
 src/libmongoc/tests/test-mongoc-uri.c         | 51 +++++++++++++++++++
 7 files changed, 93 insertions(+), 20 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-client.h b/src/libmongoc/src/mongoc/mongoc-client.h
index 2b53c91b8b0..3c89c0e70a4 100644
--- a/src/libmongoc/src/mongoc/mongoc-client.h
+++ b/src/libmongoc/src/mongoc/mongoc-client.h
@@ -54,19 +54,6 @@ BSON_BEGIN_DECLS
 #endif
 
 
-#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
-/*
- * NOTE: The default socket timeout for connections is 5 minutes. This
- *       means that if your MongoDB server dies or becomes unavailable
- *       it will take 5 minutes to detect this.
- *
- *       You can change this by providing sockettimeoutms= in your
- *       connection URI.
- */
-#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
-#endif
-
-
 /**
  * mongoc_client_t:
  *
diff --git a/src/libmongoc/src/mongoc/mongoc-cluster.c b/src/libmongoc/src/mongoc/mongoc-cluster.c
index 0519ec0a179..580eb40de5d 100644
--- a/src/libmongoc/src/mongoc/mongoc-cluster.c
+++ b/src/libmongoc/src/mongoc/mongoc-cluster.c
@@ -2502,8 +2502,7 @@ void
 mongoc_cluster_reset_sockettimeoutms(mongoc_cluster_t *cluster)
 {
    BSON_ASSERT_PARAM(cluster);
-   cluster->sockettimeoutms =
-      mongoc_uri_get_option_as_int32(cluster->uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+   cluster->sockettimeoutms = mongoc_uri_get_socket_timeout_ms_option(cluster->uri);
 }
 
 static uint32_t
diff --git a/src/libmongoc/src/mongoc/mongoc-uri-private.h b/src/libmongoc/src/mongoc/mongoc-uri-private.h
index 5e9dc2ac38f..887b3e3ef89 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri-private.h
@@ -55,6 +55,9 @@ _mongoc_uri_apply_query_string(mongoc_uri_t *uri, mstr_view options, bool from_d
 int32_t
 mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri);
 
+int32_t
+mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri);
+
 bool
 _mongoc_uri_requires_auth_negotiation(const mongoc_uri_t *uri);
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index d444cfdfd2f..5276fd7dab0 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -22,6 +22,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "mongoc/mongoc.h"
+
 /* strcasecmp on windows */
 #include <common-bson-dsl-private.h>
 #include <common-string-private.h>
@@ -733,7 +735,9 @@ mongoc_uri_option_is_utf8(const char *key)
           /* deprecated options with canonical equivalents */
           !strcasecmp(key, MONGOC_URI_SSLCLIENTCERTIFICATEKEYFILE) ||
           !strcasecmp(key, MONGOC_URI_SSLCLIENTCERTIFICATEKEYPASSWORD) ||
-          !strcasecmp(key, MONGOC_URI_SSLCERTIFICATEAUTHORITYFILE);
+          !strcasecmp(key, MONGOC_URI_SSLCERTIFICATEAUTHORITYFILE) ||
+          // temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts
+          !strcasecmp(key, MONGOC_URI_SOCKETTIMEOUTMS);
 }
 
 const char *
@@ -997,7 +1001,10 @@ mongoc_uri_apply_options(mongoc_uri_t *uri, const bson_t *options, bool from_dns
             MONGOC_WARNING("Empty value provided for \"%s\"", key);
          }
       } else if (mongoc_uri_option_is_int32(key)) {
-         if (0 < strlen(value)) {
+         // temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts
+         if (strcasecmp(key, MONGOC_URI_SOCKETTIMEOUTMS) == 0 && strcasecmp(value, "inf") == 0) {
+            _bson_upsert_utf8_icase(&uri->options, mstr_cstring(MONGOC_URI_SOCKETTIMEOUTMS), "inf");
+         } else if (0 < strlen(value)) {
             int32_t i32 = 42424242;
             if (mlib_i32_parse(mstr_cstring(value), &i32)) {
                goto UNSUPPORTED_VALUE;
@@ -2594,6 +2601,18 @@ mongoc_uri_get_local_threshold_option(const mongoc_uri_t *uri)
    return retval;
 }
 
+int32_t
+mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
+{
+   const char *const str_maybe = mongoc_uri_get_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, NULL);
+
+   if (str_maybe && strcasecmp(str_maybe, "inf") == 0) {
+      // TODO: log and refer to ticket number
+      return 0;
+   }
+
+   return mongoc_uri_get_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+}
 
 const char *
 mongoc_uri_get_srv_hostname(const mongoc_uri_t *uri)
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.h b/src/libmongoc/src/mongoc/mongoc-uri.h
index ecf689d6ae7..fd654268930 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri.h
@@ -33,6 +33,20 @@
 #define MONGOC_DEFAULT_PORT 27017
 #endif
 
+#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
+/*
+ * NOTE: The default socket timeout for connections is 5 minutes. This
+ *       means that if your MongoDB server dies or becomes unavailable
+ *       it will take 5 minutes to detect this.
+ *
+ *       You can change this by providing sockettimeoutms= in your
+ *       connection URI.
+ *
+ *       This default may be changed to 0 (unlimited timeout)
+ */
+#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
+#endif
+
 #define MONGOC_URI_APPNAME "appname"
 #define MONGOC_URI_AUTHMECHANISM "authmechanism"
 #define MONGOC_URI_AUTHMECHANISMPROPERTIES "authmechanismproperties"
diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index 7bc0447fec2..717e94013a3 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3837,10 +3837,10 @@ test_killCursors(void)
 }
 
 static void
-test_socketTimeoutMS_zero(void)
+test_socketTimeoutMS_unlimited(void)
 {
    mongoc_uri_t *const uri = test_framework_get_uri();
-   mongoc_uri_set_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, 0);
+   mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf");
 
    mongoc_client_t *const client = test_framework_client_new_from_uri(uri, NULL);
 
@@ -4091,5 +4091,5 @@ test_client_install(TestSuite *suite)
                      test_framework_skip_if_no_server_ssl);
 #endif
    TestSuite_AddLive(suite, "/Client/killCursors", test_killCursors);
-   TestSuite_AddLive(suite, "/Client/socketTimeoutMS_zero", test_socketTimeoutMS_zero);
+   TestSuite_AddLive(suite, "/Client/socketTimeoutMS_unlimited", test_socketTimeoutMS_unlimited);
 }
diff --git a/src/libmongoc/tests/test-mongoc-uri.c b/src/libmongoc/tests/test-mongoc-uri.c
index dd4d1036199..2b19b7b66d0 100644
--- a/src/libmongoc/tests/test-mongoc-uri.c
+++ b/src/libmongoc/tests/test-mongoc-uri.c
@@ -2610,6 +2610,56 @@ test_mongoc_uri_local_threshold_ms(void)
    mongoc_uri_destroy(uri);
 }
 
+static void
+test_mongoc_uri_socket_timeout_ms(void)
+{
+   mongoc_uri_t *uri = mongoc_uri_new("mongodb://localhost/");
+   ASSERT(uri);
+
+   // If sockettimeoutms is not set, return the C Driver's default
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+
+   ASSERT(mongoc_uri_set_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, 99));
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 99);
+
+   // TODO:link to ticket explaining "inf"
+   ASSERT(mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf"));
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 0);
+
+   mongoc_uri_destroy(uri);
+
+   uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=99");
+   ASSERT(uri);
+
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 99);
+
+   mongoc_uri_destroy(uri);
+
+   uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=inf");
+   ASSERT(uri);
+
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 0);
+
+   mongoc_uri_destroy(uri);
+
+   uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=0");
+   ASSERT(uri);
+
+   // TODO:link to ticket explaining "inf"
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), !=, 0);
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+
+   mongoc_uri_destroy(uri);
+
+   capture_logs(true);
+
+   uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=garbage");
+   ASSERT(!uri);
+   ASSERT_CAPTURED_LOG("mongoc_uri_get_socket_timeout_ms_option",
+                       MONGOC_LOG_LEVEL_WARNING,
+                       "Unsupported value for \"sockettimeoutms\": \"garbage\"");
+}
+
 
 #define INVALID(_uri, _host)                                                                             \
    ASSERT_WITH_MSG(!mongoc_uri_upsert_host((_uri), (_host), 1, &error), "expected host upsert to fail"); \
@@ -3323,6 +3373,7 @@ test_uri_install(TestSuite *suite)
    TestSuite_Add(suite, "/Uri/compound_setters", test_mongoc_uri_compound_setters);
    TestSuite_Add(suite, "/Uri/long_hostname", test_mongoc_uri_long_hostname);
    TestSuite_Add(suite, "/Uri/local_threshold_ms", test_mongoc_uri_local_threshold_ms);
+   TestSuite_Add(suite, "/Uri/socket_timeout_ms", test_mongoc_uri_socket_timeout_ms);
    TestSuite_Add(suite, "/Uri/srv", test_mongoc_uri_srv);
    TestSuite_Add(suite, "/Uri/dns_options", test_mongoc_uri_dns_options);
    TestSuite_Add(suite, "/Uri/utf8", test_mongoc_uri_utf8);

From d4d1f45ae004e75bfa91b1e58d5f527853ecc550 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Tue, 9 Dec 2025 10:07:50 -0500
Subject: [PATCH 07/27] Set SSL opts on test client

---
 src/libmongoc/tests/test-mongoc-client.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index 717e94013a3..53dcf7c85d7 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3843,6 +3843,7 @@ test_socketTimeoutMS_unlimited(void)
    mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf");
 
    mongoc_client_t *const client = test_framework_client_new_from_uri(uri, NULL);
+   test_framework_set_ssl_opts(client);
 
    // Configure a failpoint to block on "ping" for 500ms.
    bson_error_t error;

From 4fb27cbd7fd9b23b990ad8ebb4cc65191b309878 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Tue, 9 Dec 2025 10:19:02 -0500
Subject: [PATCH 08/27] Remove include

---
 src/libmongoc/src/mongoc/mongoc-uri.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 5276fd7dab0..fc71931592e 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -22,8 +22,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "mongoc/mongoc.h"
-
 /* strcasecmp on windows */
 #include <common-bson-dsl-private.h>
 #include <common-string-private.h>

From d9811a769189e18ada1af9e9f084fe2500b5f748 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 10 Dec 2025 15:50:18 -0500
Subject: [PATCH 09/27] Apply timeout changes to OpenSSL TLS

---
 src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
index 298e0fe48d6..0bb8d954569 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
@@ -209,7 +209,7 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
    BSON_ASSERT(buf);
    BSON_ASSERT(buf_len);
 
-   if (tls->timeout_msec >= 0) {
+   if (tls->timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000);
    }
 
@@ -421,7 +421,7 @@ _mongoc_stream_tls_openssl_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec >= 0) {
+   if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
    }
 

From 969fe2606b6cd02b9ba9332628767b703c858b0a Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 11 Dec 2025 11:17:47 -0500
Subject: [PATCH 10/27] Handle case where immediate timeout is desired

---
 src/libmongoc/src/mongoc/mongoc-async-cmd.c     | 4 ++--
 src/libmongoc/src/mongoc/mongoc-stream-socket.c | 4 +++-
 src/libmongoc/src/mongoc/mongoc-stream.h        | 4 ++++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-async-cmd.c b/src/libmongoc/src/mongoc/mongoc-async-cmd.c
index 3ca7acbb163..d5baea7882d 100644
--- a/src/libmongoc/src/mongoc/mongoc-async-cmd.c
+++ b/src/libmongoc/src/mongoc/mongoc-async-cmd.c
@@ -85,8 +85,8 @@ mongoc_async_cmd_tls_setup(mongoc_stream_t *stream, int *events, void *ctx, mlib
    // Try to do a non-blocking operation, if our backend allows it
    const mlib_duration_rep_t remain_ms = //
       use_non_blocking
-         // Pass 0 for the timeout to begin / continue a non-blocking handshake
-         ? 0
+         // Pass sentinel value for the timeout to begin / continue a non-blocking handshake
+         ? MONGOC_SOCKET_TIMEOUT_NON_BLOCKING
          // Otherwise, use the deadline
          : mlib_milliseconds_count(mlib_timer_remaining(deadline));
    if (mongoc_stream_tls_handshake(tls_stream, host, mlib_assert_narrow(int32_t, remain_ms), &retry_events, error)) {
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-socket.c b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
index 9be3b3237af..1ab60dee857 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-socket.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
@@ -36,7 +36,9 @@ struct _mongoc_stream_socket_t {
 static BSON_INLINE int64_t
 get_expiration(int32_t timeout_msec)
 {
-   if (timeout_msec <= 0) {
+   if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      return 0;
+   } else if (timeout_msec <= 0) {
       return -1;
    } else {
       return (bson_get_monotonic_time() + ((int64_t)timeout_msec * 1000L));
diff --git a/src/libmongoc/src/mongoc/mongoc-stream.h b/src/libmongoc/src/mongoc/mongoc-stream.h
index 723f5febd43..c4ccd4d0db3 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream.h
@@ -23,10 +23,14 @@
 #include <mongoc/mongoc-macros.h>
 #include <mongoc/mongoc-socket.h>
 
+#include <stdint.h>
+
 
 BSON_BEGIN_DECLS
 
 
+#define MONGOC_SOCKET_TIMEOUT_NON_BLOCKING INT32_MIN
+
 typedef struct _mongoc_stream_t mongoc_stream_t;
 
 typedef struct _mongoc_stream_poll_t {

From 6e1a6db86ff3fd14433d87017fe46a8dd5275a0a Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 11 Dec 2025 14:27:24 -0500
Subject: [PATCH 11/27] Apply timeout channels to secure channel

---
 src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
index 0d4b70d616e..f35b1775931 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
@@ -695,7 +695,7 @@ _mongoc_stream_tls_secure_channel_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec >= 0) {
+   if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
    }
 

From 52c1672353dd0607c3a5a231f690e7c2cc1cc421 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Tue, 16 Dec 2025 14:21:23 -0500
Subject: [PATCH 12/27] Fix non-blocking timeout handling in TLS

---
 src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c      | 8 ++++++--
 .../src/mongoc/mongoc-stream-tls-secure-channel.c         | 4 +++-
 .../src/mongoc/mongoc-stream-tls-secure-transport.c       | 8 ++++++--
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
index 0bb8d954569..65238baf335 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
@@ -211,6 +211,8 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
 
    if (tls->timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000);
+   } else if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      expire = bson_get_monotonic_time();
    }
 
    BSON_ASSERT(mlib_in_range(int, buf_len));
@@ -228,7 +230,7 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
             mongoc_counter_streams_timeout_inc();
          }
 
-         tls->timeout_msec = 0;
+         tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
       } else {
          tls->timeout_msec = (expire - now) / 1000;
       }
@@ -423,6 +425,8 @@ _mongoc_stream_tls_openssl_readv(
 
    if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
+   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      expire = bson_get_monotonic_time();
    }
 
    for (i = 0; i < iovcnt; i++) {
@@ -457,7 +461,7 @@ _mongoc_stream_tls_openssl_readv(
                   RETURN(-1);
                }
 
-               tls->timeout_msec = 0;
+               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
                tls->timeout_msec = (expire - now) / 1000L;
             }
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
index f35b1775931..d44789318ec 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
@@ -697,6 +697,8 @@ _mongoc_stream_tls_secure_channel_readv(
 
    if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
+   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      expire = bson_get_monotonic_time();
    }
 
    for (i = 0; i < iovcnt; i++) {
@@ -726,7 +728,7 @@ _mongoc_stream_tls_secure_channel_readv(
                   RETURN(-1);
                }
 
-               tls->timeout_msec = 0;
+               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
                tls->timeout_msec = (expire - now) / 1000L;
             }
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
index 9f84a56510b..432e40f7daf 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
@@ -123,6 +123,8 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
 
    if (tls->timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000UL);
+   } else if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      expire = bson_get_monotonic_time();
    }
 
    status = SSLWrite(secure_transport->ssl_ctx_ref, buf, buf_len, (size_t *)&write_ret);
@@ -147,7 +149,7 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
             mongoc_counter_streams_timeout_inc();
          }
 
-         tls->timeout_msec = 0;
+         tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
       } else {
          tls->timeout_msec = (expire - now) / 1000L;
       }
@@ -302,6 +304,8 @@ _mongoc_stream_tls_secure_transport_readv(
 
    if (timeout_msec > 0) {
       expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
+   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+      expire = bson_get_monotonic_time();
    }
 
    for (i = 0; i < iovcnt; i++) {
@@ -338,7 +342,7 @@ _mongoc_stream_tls_secure_transport_readv(
                   RETURN(-1);
                }
 
-               tls->timeout_msec = 0;
+               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
                tls->timeout_msec = (expire - now) / 1000L;
             }

From 6d0b80989e371032a518c71c4929089610bf8d84 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Tue, 16 Dec 2025 15:31:43 -0500
Subject: [PATCH 13/27] Fix handling of sub-millisecond timeouts

---
 src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c | 12 ++++++++----
 .../src/mongoc/mongoc-stream-tls-secure-channel.c    |  6 ++++--
 .../src/mongoc/mongoc-stream-tls-secure-transport.c  | 12 ++++++++----
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
index 65238baf335..41340f9f87c 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
@@ -225,14 +225,16 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
    if (expire) {
       now = bson_get_monotonic_time();
 
-      if ((expire - now) < 0) {
+      const int64_t remaining_msec = (expire - now) / 1000L;
+
+      if (remaining_msec <= 0) {
          if (mlib_cmp(ret, <, buf_len)) {
             mongoc_counter_streams_timeout_inc();
          }
 
          tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
       } else {
-         tls->timeout_msec = (expire - now) / 1000;
+         tls->timeout_msec = remaining_msec;
       }
    }
 
@@ -450,7 +452,9 @@ _mongoc_stream_tls_openssl_readv(
          if (expire) {
             now = bson_get_monotonic_time();
 
-            if ((expire - now) < 0) {
+            const int64_t remaining_msec = (expire - now) / 1000L;
+
+            if (remaining_msec <= 0) {
                if (read_ret == 0) {
                   mongoc_counter_streams_timeout_inc();
 #ifdef _WIN32
@@ -463,7 +467,7 @@ _mongoc_stream_tls_openssl_readv(
 
                tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
-               tls->timeout_msec = (expire - now) / 1000L;
+               tls->timeout_msec = remaining_msec;
             }
          }
 
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
index d44789318ec..1d25734c56f 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
@@ -721,7 +721,9 @@ _mongoc_stream_tls_secure_channel_readv(
          if (expire) {
             now = bson_get_monotonic_time();
 
-            if ((expire - now) < 0) {
+            const int64_t remaining_msec = (expire - now) / 1000L;
+
+            if (remaining_msec <= 0) {
                if (read_ret == 0) {
                   mongoc_counter_streams_timeout_inc();
                   errno = ETIMEDOUT;
@@ -730,7 +732,7 @@ _mongoc_stream_tls_secure_channel_readv(
 
                tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
-               tls->timeout_msec = (expire - now) / 1000L;
+               tls->timeout_msec = remaining_msec;
             }
          }
 
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
index 432e40f7daf..15647b943d8 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
@@ -144,14 +144,16 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
    if (expire) {
       now = bson_get_monotonic_time();
 
-      if ((expire - now) < 0) {
+      const int64_t remaining_msec = (expire - now) / 1000L;
+
+      if (remaining_msec <= 0) {
          if (write_ret < (ssize_t)buf_len) {
             mongoc_counter_streams_timeout_inc();
          }
 
          tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
       } else {
-         tls->timeout_msec = (expire - now) / 1000L;
+         tls->timeout_msec = remaining_msec;
       }
    }
 
@@ -335,7 +337,9 @@ _mongoc_stream_tls_secure_transport_readv(
          if (expire) {
             now = bson_get_monotonic_time();
 
-            if ((expire - now) < 0) {
+            const int64_t remaining_msec = (expire - now) / 1000L;
+
+            if (remaining_msec <= 0) {
                if (read_ret == 0) {
                   mongoc_counter_streams_timeout_inc();
                   errno = ETIMEDOUT;
@@ -344,7 +348,7 @@ _mongoc_stream_tls_secure_transport_readv(
 
                tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
             } else {
-               tls->timeout_msec = (expire - now) / 1000L;
+               tls->timeout_msec = remaining_msec;
             }
          }
 

From f8056fd8f7e6a63bdb822e47d1c01ad6f8198e81 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 11:10:43 -0500
Subject: [PATCH 14/27] Refactor timeout handling to be less error-prone

---
 src/libmongoc/src/mongoc/mongoc-async-cmd.c   |  2 +-
 .../src/mongoc/mongoc-stream-socket.c         |  2 +-
 .../src/mongoc/mongoc-stream-tls-openssl.c    | 54 ++++---------------
 .../src/mongoc/mongoc-stream-tls-private.h    |  8 +++
 .../mongoc/mongoc-stream-tls-secure-channel.c | 28 +++-------
 .../mongoc-stream-tls-secure-transport.c      | 52 ++++--------------
 src/libmongoc/src/mongoc/mongoc-stream-tls.c  | 30 +++++++++++
 src/libmongoc/src/mongoc/mongoc-stream.h      |  3 +-
 src/libmongoc/src/mongoc/mongoc-uri.c         |  2 +-
 src/libmongoc/tests/test-mongoc-uri.c         |  6 +--
 10 files changed, 73 insertions(+), 114 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-async-cmd.c b/src/libmongoc/src/mongoc/mongoc-async-cmd.c
index d5baea7882d..e713b35c7c0 100644
--- a/src/libmongoc/src/mongoc/mongoc-async-cmd.c
+++ b/src/libmongoc/src/mongoc/mongoc-async-cmd.c
@@ -86,7 +86,7 @@ mongoc_async_cmd_tls_setup(mongoc_stream_t *stream, int *events, void *ctx, mlib
    const mlib_duration_rep_t remain_ms = //
       use_non_blocking
          // Pass sentinel value for the timeout to begin / continue a non-blocking handshake
-         ? MONGOC_SOCKET_TIMEOUT_NON_BLOCKING
+         ? MONGOC_SOCKET_TIMEOUT_IMMEDIATE
          // Otherwise, use the deadline
          : mlib_milliseconds_count(mlib_timer_remaining(deadline));
    if (mongoc_stream_tls_handshake(tls_stream, host, mlib_assert_narrow(int32_t, remain_ms), &retry_events, error)) {
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-socket.c b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
index 1ab60dee857..a6bfaabba86 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-socket.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-socket.c
@@ -36,7 +36,7 @@ struct _mongoc_stream_socket_t {
 static BSON_INLINE int64_t
 get_expiration(int32_t timeout_msec)
 {
-   if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
+   if (timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE) {
       return 0;
    } else if (timeout_msec <= 0) {
       return -1;
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
index 41340f9f87c..106099b1e15 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-openssl.c
@@ -201,19 +201,13 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
 {
    mongoc_stream_tls_openssl_t *openssl = (mongoc_stream_tls_openssl_t *)tls->ctx;
    ssize_t ret;
-   int64_t now;
-   int64_t expire = 0;
    ENTRY;
 
    BSON_ASSERT(tls);
    BSON_ASSERT(buf);
    BSON_ASSERT(buf_len);
 
-   if (tls->timeout_msec > 0) {
-      expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000);
-   } else if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
-      expire = bson_get_monotonic_time();
-   }
+   const mlib_timer timer = _mongoc_stream_tls_timer_from_timeout_msec(tls->timeout_msec);
 
    BSON_ASSERT(mlib_in_range(int, buf_len));
    ret = BIO_write(openssl->bio, buf, (int)buf_len);
@@ -222,20 +216,10 @@ _mongoc_stream_tls_openssl_write(mongoc_stream_tls_t *tls, char *buf, size_t buf
       return ret;
    }
 
-   if (expire) {
-      now = bson_get_monotonic_time();
-
-      const int64_t remaining_msec = (expire - now) / 1000L;
-
-      if (remaining_msec <= 0) {
-         if (mlib_cmp(ret, <, buf_len)) {
-            mongoc_counter_streams_timeout_inc();
-         }
+   tls->timeout_msec = _mongoc_stream_tls_timer_to_timeout_msec(timer);
 
-         tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
-      } else {
-         tls->timeout_msec = remaining_msec;
-      }
+   if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE && mlib_cmp(ret, <, buf_len)) {
+      mongoc_counter_streams_timeout_inc();
    }
 
    RETURN(ret);
@@ -415,8 +399,6 @@ _mongoc_stream_tls_openssl_readv(
    size_t i;
    int read_ret;
    size_t iov_pos = 0;
-   int64_t now;
-   int64_t expire = 0;
    ENTRY;
 
    BSON_ASSERT(tls);
@@ -425,11 +407,7 @@ _mongoc_stream_tls_openssl_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec > 0) {
-      expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
-   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
-      expire = bson_get_monotonic_time();
-   }
+   const mlib_timer timer = _mongoc_stream_tls_timer_from_timeout_msec(timeout_msec);
 
    for (i = 0; i < iovcnt; i++) {
       iov_pos = 0;
@@ -449,26 +427,16 @@ _mongoc_stream_tls_openssl_readv(
             return -1;
          }
 
-         if (expire) {
-            now = bson_get_monotonic_time();
-
-            const int64_t remaining_msec = (expire - now) / 1000L;
+         tls->timeout_msec = _mongoc_stream_tls_timer_to_timeout_msec(timer);
 
-            if (remaining_msec <= 0) {
-               if (read_ret == 0) {
-                  mongoc_counter_streams_timeout_inc();
+         if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE && read_ret == 0) {
+            mongoc_counter_streams_timeout_inc();
 #ifdef _WIN32
-                  errno = WSAETIMEDOUT;
+            errno = WSAETIMEDOUT;
 #else
-                  errno = ETIMEDOUT;
+            errno = ETIMEDOUT;
 #endif
-                  RETURN(-1);
-               }
-
-               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
-            } else {
-               tls->timeout_msec = remaining_msec;
-            }
+            RETURN(-1);
          }
 
          ret += read_ret;
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-private.h b/src/libmongoc/src/mongoc/mongoc-stream-tls-private.h
index c17e992ff28..f7624492aab 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-private.h
@@ -28,6 +28,8 @@
 
 #include <bson/bson.h>
 
+#include <mlib/timer.h>
+
 #ifdef MONGOC_ENABLE_SSL_OPENSSL
 #include <openssl/ssl.h>
 #endif
@@ -67,6 +69,12 @@ mongoc_stream_tls_new_with_secure_channel_cred(mongoc_stream_t *base_stream,
                                                mongoc_shared_ptr secure_channel_cred_ptr) BSON_GNUC_WARN_UNUSED_RESULT;
 #endif // MONGOC_ENABLE_SSL_SECURE_CHANNEL
 
+mlib_timer
+_mongoc_stream_tls_timer_from_timeout_msec(int64_t timeout_msec);
+
+int64_t
+_mongoc_stream_tls_timer_to_timeout_msec(mlib_timer timer);
+
 BSON_END_DECLS
 
 #endif /* MONGOC_STREAM_TLS_PRIVATE_H */
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
index 1d25734c56f..79dd8a6aaf6 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-channel.c
@@ -685,8 +685,6 @@ _mongoc_stream_tls_secure_channel_readv(
    ssize_t ret = 0;
    size_t i;
    size_t iov_pos = 0;
-   int64_t now;
-   int64_t expire = 0;
 
    BSON_ASSERT(iov);
    BSON_ASSERT(iovcnt);
@@ -695,11 +693,7 @@ _mongoc_stream_tls_secure_channel_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec > 0) {
-      expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
-   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
-      expire = bson_get_monotonic_time();
-   }
+   const mlib_timer timer = _mongoc_stream_tls_timer_from_timeout_msec(timeout_msec);
 
    for (i = 0; i < iovcnt; i++) {
       iov_pos = 0;
@@ -718,22 +712,12 @@ _mongoc_stream_tls_secure_channel_readv(
             RETURN(-1);
          }
 
-         if (expire) {
-            now = bson_get_monotonic_time();
-
-            const int64_t remaining_msec = (expire - now) / 1000L;
-
-            if (remaining_msec <= 0) {
-               if (read_ret == 0) {
-                  mongoc_counter_streams_timeout_inc();
-                  errno = ETIMEDOUT;
-                  RETURN(-1);
-               }
+         tls->timeout_msec = _mongoc_stream_tls_timer_to_timeout_msec(timer);
 
-               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
-            } else {
-               tls->timeout_msec = remaining_msec;
-            }
+         if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE && read_ret == 0) {
+            mongoc_counter_streams_timeout_inc();
+            errno = ETIMEDOUT;
+            RETURN(-1);
          }
 
          ret += read_ret;
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
index 15647b943d8..5b246694106 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls-secure-transport.c
@@ -115,17 +115,11 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
    mongoc_stream_tls_t *tls = (mongoc_stream_tls_t *)stream;
    mongoc_stream_tls_secure_transport_t *secure_transport = (mongoc_stream_tls_secure_transport_t *)tls->ctx;
    ssize_t write_ret;
-   int64_t now;
-   int64_t expire = 0;
 
    ENTRY;
    BSON_ASSERT(secure_transport);
 
-   if (tls->timeout_msec > 0) {
-      expire = bson_get_monotonic_time() + (tls->timeout_msec * 1000UL);
-   } else if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
-      expire = bson_get_monotonic_time();
-   }
+   const mlib_timer timer = _mongoc_stream_tls_timer_from_timeout_msec(tls->timeout_msec);
 
    status = SSLWrite(secure_transport->ssl_ctx_ref, buf, buf_len, (size_t *)&write_ret);
 
@@ -141,20 +135,10 @@ _mongoc_stream_tls_secure_transport_write(mongoc_stream_t *stream, char *buf, si
       RETURN(-1);
    }
 
-   if (expire) {
-      now = bson_get_monotonic_time();
-
-      const int64_t remaining_msec = (expire - now) / 1000L;
+   tls->timeout_msec = _mongoc_stream_tls_timer_to_timeout_msec(timer);
 
-      if (remaining_msec <= 0) {
-         if (write_ret < (ssize_t)buf_len) {
-            mongoc_counter_streams_timeout_inc();
-         }
-
-         tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
-      } else {
-         tls->timeout_msec = remaining_msec;
-      }
+   if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE && write_ret < (ssize_t)buf_len) {
+      mongoc_counter_streams_timeout_inc();
    }
 
    RETURN(write_ret);
@@ -291,8 +275,6 @@ _mongoc_stream_tls_secure_transport_readv(
    size_t i;
    size_t read_ret;
    size_t iov_pos = 0;
-   int64_t now;
-   int64_t expire = 0;
    size_t to_read;
    size_t remaining_buf_size;
    size_t remaining_to_read;
@@ -304,11 +286,7 @@ _mongoc_stream_tls_secure_transport_readv(
 
    tls->timeout_msec = timeout_msec;
 
-   if (timeout_msec > 0) {
-      expire = bson_get_monotonic_time() + (timeout_msec * 1000UL);
-   } else if (timeout_msec == MONGOC_SOCKET_TIMEOUT_NON_BLOCKING) {
-      expire = bson_get_monotonic_time();
-   }
+   const mlib_timer timer = _mongoc_stream_tls_timer_from_timeout_msec(timeout_msec);
 
    for (i = 0; i < iovcnt; i++) {
       iov_pos = 0;
@@ -334,22 +312,12 @@ _mongoc_stream_tls_secure_transport_readv(
             RETURN(-1);
          }
 
-         if (expire) {
-            now = bson_get_monotonic_time();
-
-            const int64_t remaining_msec = (expire - now) / 1000L;
-
-            if (remaining_msec <= 0) {
-               if (read_ret == 0) {
-                  mongoc_counter_streams_timeout_inc();
-                  errno = ETIMEDOUT;
-                  RETURN(-1);
-               }
+         tls->timeout_msec = _mongoc_stream_tls_timer_to_timeout_msec(timer);
 
-               tls->timeout_msec = MONGOC_SOCKET_TIMEOUT_NON_BLOCKING;
-            } else {
-               tls->timeout_msec = remaining_msec;
-            }
+         if (tls->timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE && read_ret == 0) {
+            mongoc_counter_streams_timeout_inc();
+            errno = ETIMEDOUT;
+            RETURN(-1);
          }
 
          ret += read_ret;
diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls.c b/src/libmongoc/src/mongoc/mongoc-stream-tls.c
index 3c2494f410c..4a5ad7f666e 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls.c
@@ -237,4 +237,34 @@ mongoc_stream_tls_new_with_secure_channel_cred(mongoc_stream_t *base_stream,
 }
 #endif // MONGOC_ENABLE_SSL_SECURE_CHANNEL
 
+mlib_timer
+_mongoc_stream_tls_timer_from_timeout_msec(int64_t timeout_msec)
+{
+   if (timeout_msec == MONGOC_SOCKET_TIMEOUT_IMMEDIATE) {
+      return mlib_expires_after(0, ms);
+   } else if (timeout_msec <= 0) {
+      return mlib_expires_never();
+   } else {
+      return mlib_expires_after(timeout_msec, ms);
+   }
+}
+
+int64_t
+_mongoc_stream_tls_timer_to_timeout_msec(mlib_timer timer)
+{
+   const mlib_timer never = mlib_expires_never();
+
+   if (mlib_time_cmp(timer.expires_at, never.expires_at) == mlib_equal) {
+      return MONGOC_SOCKET_TIMEOUT_INFINITE;
+   }
+
+   const int64_t remaining_msec = mlib_milliseconds_count(mlib_timer_remaining(timer));
+
+   if (remaining_msec <= 0) {
+      return MONGOC_SOCKET_TIMEOUT_IMMEDIATE;
+   } else {
+      return remaining_msec;
+   }
+}
+
 #endif
diff --git a/src/libmongoc/src/mongoc/mongoc-stream.h b/src/libmongoc/src/mongoc/mongoc-stream.h
index c4ccd4d0db3..07058787af8 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream.h
@@ -29,7 +29,8 @@
 BSON_BEGIN_DECLS
 
 
-#define MONGOC_SOCKET_TIMEOUT_NON_BLOCKING INT32_MIN
+#define MONGOC_SOCKET_TIMEOUT_INFINITE 0
+#define MONGOC_SOCKET_TIMEOUT_IMMEDIATE INT32_MIN
 
 typedef struct _mongoc_stream_t mongoc_stream_t;
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 9e2b607b52e..7556be19e71 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2611,7 +2611,7 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
 
    if (str_maybe && strcasecmp(str_maybe, "inf") == 0) {
       // TODO: log and refer to ticket number
-      return 0;
+      return MONGOC_SOCKET_TIMEOUT_INFINITE;
    }
 
    return mongoc_uri_get_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
diff --git a/src/libmongoc/tests/test-mongoc-uri.c b/src/libmongoc/tests/test-mongoc-uri.c
index 7ae3c0f2204..4168718091d 100644
--- a/src/libmongoc/tests/test-mongoc-uri.c
+++ b/src/libmongoc/tests/test-mongoc-uri.c
@@ -2624,7 +2624,7 @@ test_mongoc_uri_socket_timeout_ms(void)
 
    // TODO:link to ticket explaining "inf"
    ASSERT(mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf"));
-   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 0);
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_SOCKET_TIMEOUT_INFINITE);
 
    mongoc_uri_destroy(uri);
 
@@ -2638,7 +2638,7 @@ test_mongoc_uri_socket_timeout_ms(void)
    uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=inf");
    ASSERT(uri);
 
-   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 0);
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_SOCKET_TIMEOUT_INFINITE);
 
    mongoc_uri_destroy(uri);
 
@@ -2646,7 +2646,7 @@ test_mongoc_uri_socket_timeout_ms(void)
    ASSERT(uri);
 
    // TODO:link to ticket explaining "inf"
-   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), !=, 0);
+   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), !=, MONGOC_SOCKET_TIMEOUT_INFINITE);
    ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
 
    mongoc_uri_destroy(uri);

From 2a458ef95faefe922d93753dd61d67ff98c8b41a Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 12:38:49 -0500
Subject: [PATCH 15/27] Rename test case

---
 src/libmongoc/tests/test-mongoc-client.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index 53dcf7c85d7..fec13397e01 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3837,7 +3837,7 @@ test_killCursors(void)
 }
 
 static void
-test_socketTimeoutMS_unlimited(void)
+test_socketTimeoutMS_infinite(void)
 {
    mongoc_uri_t *const uri = test_framework_get_uri();
    mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf");
@@ -4092,5 +4092,5 @@ test_client_install(TestSuite *suite)
                      test_framework_skip_if_no_server_ssl);
 #endif
    TestSuite_AddLive(suite, "/Client/killCursors", test_killCursors);
-   TestSuite_AddLive(suite, "/Client/socketTimeoutMS_unlimited", test_socketTimeoutMS_unlimited);
+   TestSuite_AddLive(suite, "/Client/socketTimeoutMS_infinite", test_socketTimeoutMS_infinite);
 }

From 2261cfd2df90c812e3ae68fdd18e608037e45b08 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 12:42:24 -0500
Subject: [PATCH 16/27] Remove timing checks from test

---
 src/libmongoc/tests/test-mongoc-client.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index fec13397e01..9ffd8321ccd 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3860,19 +3860,10 @@ test_socketTimeoutMS_infinite(void)
       &error);
    ASSERT_OR_PRINT(ok, error);
 
-   // Expect "ping" to take 500ms.
-   const mlib_time_point start = mlib_now();
-
-   // Send "ping":
+   // Ensure we can send a ping without timing out:
    ok = mongoc_client_command_simple(client, "admin", tmp_bson(BSON_STR({"ping" : 1})), NULL, NULL, &error);
    ASSERT_OR_PRINT(ok, error);
 
-   const mlib_time_point end = mlib_now();
-
-   const mlib_duration elapsed = mlib_time_difference(end, start);
-
-   ASSERT_CMPINT64(mlib_microseconds_count(elapsed), >=, mlib_microseconds_count(mlib_duration(500, ms)));
-
    mongoc_client_destroy(client);
    mongoc_uri_destroy(uri);
 }

From 93b32a82574aae77c11cc3e75aacadd39952189c Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 13:44:04 -0500
Subject: [PATCH 17/27] Refer to future fix ticket number

---
 src/libmongoc/src/mongoc/mongoc-uri.c    | 7 ++++---
 src/libmongoc/src/mongoc/mongoc-uri.h    | 2 +-
 src/libmongoc/tests/test-mongoc-client.c | 1 +
 src/libmongoc/tests/test-mongoc-uri.c    | 7 +++----
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 7556be19e71..776148a6a54 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -734,7 +734,7 @@ mongoc_uri_option_is_utf8(const char *key)
           !strcasecmp(key, MONGOC_URI_SSLCLIENTCERTIFICATEKEYFILE) ||
           !strcasecmp(key, MONGOC_URI_SSLCLIENTCERTIFICATEKEYPASSWORD) ||
           !strcasecmp(key, MONGOC_URI_SSLCERTIFICATEAUTHORITYFILE) ||
-          // temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts
+          // CDRIVER-6177: Temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts.
           !strcasecmp(key, MONGOC_URI_SOCKETTIMEOUTMS);
 }
 
@@ -1004,7 +1004,7 @@ mongoc_uri_apply_options(mongoc_uri_t *uri, const bson_t *options, bool from_dns
             MONGOC_WARNING("Empty value provided for \"%s\"", key);
          }
       } else if (mongoc_uri_option_is_int32(key)) {
-         // temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts
+         // CDRIVER-6177: Temporarily allow `socketTimeoutMS=inf` to support unlimited timeouts.
          if (strcasecmp(key, MONGOC_URI_SOCKETTIMEOUTMS) == 0 && strcasecmp(value, "inf") == 0) {
             _bson_upsert_utf8_icase(&uri->options, mstr_cstring(MONGOC_URI_SOCKETTIMEOUTMS), "inf");
          } else if (0 < strlen(value)) {
@@ -2610,7 +2610,8 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
    const char *const str_maybe = mongoc_uri_get_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, NULL);
 
    if (str_maybe && strcasecmp(str_maybe, "inf") == 0) {
-      // TODO: log and refer to ticket number
+      // CDRIVER-6177: To avoid a breaking change, use `socketTimeoutMS=inf` to specify an infinite timeout instead of
+      // `socketTimeoutMS=0`.
       return MONGOC_SOCKET_TIMEOUT_INFINITE;
    }
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.h b/src/libmongoc/src/mongoc/mongoc-uri.h
index fd654268930..bd87243fb24 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri.h
@@ -42,7 +42,7 @@
  *       You can change this by providing sockettimeoutms= in your
  *       connection URI.
  *
- *       This default may be changed to 0 (unlimited timeout)
+ *       CDRIVER-6177: This default is not spec compliant.
  */
 #define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
 #endif
diff --git a/src/libmongoc/tests/test-mongoc-client.c b/src/libmongoc/tests/test-mongoc-client.c
index 9ffd8321ccd..f2481b6d70c 100644
--- a/src/libmongoc/tests/test-mongoc-client.c
+++ b/src/libmongoc/tests/test-mongoc-client.c
@@ -3840,6 +3840,7 @@ static void
 test_socketTimeoutMS_infinite(void)
 {
    mongoc_uri_t *const uri = test_framework_get_uri();
+   // CDRIVER-6177: We must use "inf" instead of 0 to disable the timeout.
    mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf");
 
    mongoc_client_t *const client = test_framework_client_new_from_uri(uri, NULL);
diff --git a/src/libmongoc/tests/test-mongoc-uri.c b/src/libmongoc/tests/test-mongoc-uri.c
index 4168718091d..84f133ff966 100644
--- a/src/libmongoc/tests/test-mongoc-uri.c
+++ b/src/libmongoc/tests/test-mongoc-uri.c
@@ -2616,13 +2616,13 @@ test_mongoc_uri_socket_timeout_ms(void)
    mongoc_uri_t *uri = mongoc_uri_new("mongodb://localhost/");
    ASSERT(uri);
 
-   // If sockettimeoutms is not set, return the C Driver's default
+   // If `socketTimeoutMS` is not set, return the C Driver's default.
    ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
 
    ASSERT(mongoc_uri_set_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, 99));
    ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, 99);
 
-   // TODO:link to ticket explaining "inf"
+   // CDRIVER-6177: `socketTimeoutMS=inf` is used to specify an infinite timeout instead of `socketTimeoutMS=0`.
    ASSERT(mongoc_uri_set_option_as_utf8(uri, MONGOC_URI_SOCKETTIMEOUTMS, "inf"));
    ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_SOCKET_TIMEOUT_INFINITE);
 
@@ -2645,8 +2645,7 @@ test_mongoc_uri_socket_timeout_ms(void)
    uri = mongoc_uri_new("mongodb://localhost/?" MONGOC_URI_SOCKETTIMEOUTMS "=0");
    ASSERT(uri);
 
-   // TODO:link to ticket explaining "inf"
-   ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), !=, MONGOC_SOCKET_TIMEOUT_INFINITE);
+   // CDRIVER-6177: `socketTimeoutMS=0` is treated as unset, so the default is used instead.
    ASSERT_CMPINT32(mongoc_uri_get_socket_timeout_ms_option(uri), ==, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
 
    mongoc_uri_destroy(uri);

From dfac42d8360ec5d49a6f943d39fcfbb69321fb15 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 14:02:35 -0500
Subject: [PATCH 18/27] Warn if socketTimeoutMS=0 is specified

---
 src/libmongoc/src/mongoc/mongoc-uri.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 776148a6a54..e35f29b28c2 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2615,7 +2615,24 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
       return MONGOC_SOCKET_TIMEOUT_INFINITE;
    }
 
-   return mongoc_uri_get_option_as_int32(uri, MONGOC_URI_SOCKETTIMEOUTMS, MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+   const bson_t *const options = mongoc_uri_get_options(uri);
+   bson_iter_t iter;
+
+   if (options && bson_iter_init_find_case(&iter, options, MONGOC_URI_SOCKETTIMEOUTMS) &&
+       BSON_ITER_HOLDS_INT32(&iter)) {
+      int32_t const value = bson_iter_int32(&iter);
+
+      if (value == 0) {
+         MONGOC_WARNING("`socketTimeoutMS=0` cannot be used to disable socket timeouts. The default of %" PRId64
+                        " will be used instead. To disable socket timeouts, use `socketTimeoutMS=inf`.",
+                        (int64_t)MONGOC_DEFAULT_SOCKETTIMEOUTMS);
+         return MONGOC_DEFAULT_SOCKETTIMEOUTMS;
+      } else {
+         return value;
+      }
+   }
+
+   return MONGOC_DEFAULT_SOCKETTIMEOUTMS;
 }
 
 const char *

From 3c59307ef31e161e677fdf2ee4556b2dd085a94d Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 14:48:16 -0500
Subject: [PATCH 19/27] Add comment with ticket number

---
 src/libmongoc/src/mongoc/mongoc-uri.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index e35f29b28c2..aa9c4004df4 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2623,6 +2623,7 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
       int32_t const value = bson_iter_int32(&iter);
 
       if (value == 0) {
+         // See CDRIVER-6177.
          MONGOC_WARNING("`socketTimeoutMS=0` cannot be used to disable socket timeouts. The default of %" PRId64
                         " will be used instead. To disable socket timeouts, use `socketTimeoutMS=inf`.",
                         (int64_t)MONGOC_DEFAULT_SOCKETTIMEOUTMS);

From 7f4a63c4254be51128a980c68f361c5a1ad8a43b Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Wed, 17 Dec 2025 15:04:11 -0500
Subject: [PATCH 20/27] Document socketTimeoutMS=inf

---
 src/libmongoc/doc/mongoc_uri_t.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libmongoc/doc/mongoc_uri_t.rst b/src/libmongoc/doc/mongoc_uri_t.rst
index fd2ba609a7d..6a1ddcf996d 100644
--- a/src/libmongoc/doc/mongoc_uri_t.rst
+++ b/src/libmongoc/doc/mongoc_uri_t.rst
@@ -115,6 +115,8 @@ MONGOC_URI_SRVMAXHOSTS                     srvmaxhosts                       0
   The meaning of a timeout of ``0`` or a negative value may vary depending on the operation being executed, even when specified by the same URI option.
   To specify the documented default value for a \*timeoutMS option, use the `MONGOC_DEFAULT_*` constants defined in ``mongoc-client.h`` instead.
 
+  In the case of socketTimeoutMS, to disable the timeout completely (i.e., an infinite timeout), use ``socketTimeoutMS=inf``.
+
 Authentication Options
 ----------------------
 

From 34f63a54048bb8dda1915676f15e87b9a1f4ac6d Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 08:38:24 -0500
Subject: [PATCH 21/27] Document socketTimeoutMS=inf as a C Driver extension

---
 src/libmongoc/doc/mongoc_uri_t.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libmongoc/doc/mongoc_uri_t.rst b/src/libmongoc/doc/mongoc_uri_t.rst
index 6a1ddcf996d..9404c29208b 100644
--- a/src/libmongoc/doc/mongoc_uri_t.rst
+++ b/src/libmongoc/doc/mongoc_uri_t.rst
@@ -115,7 +115,7 @@ MONGOC_URI_SRVMAXHOSTS                     srvmaxhosts                       0
   The meaning of a timeout of ``0`` or a negative value may vary depending on the operation being executed, even when specified by the same URI option.
   To specify the documented default value for a \*timeoutMS option, use the `MONGOC_DEFAULT_*` constants defined in ``mongoc-client.h`` instead.
 
-  In the case of socketTimeoutMS, to disable the timeout completely (i.e., an infinite timeout), use ``socketTimeoutMS=inf``.
+  In the case of socketTimeoutMS, to disable the timeout completely (i.e., an infinite timeout), use the C Driver extension ``socketTimeoutMS=inf``.
 
 Authentication Options
 ----------------------

From 6ff501c4b9d5d113e5c6fc7ae72c411c2a228f3d Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 08:49:20 -0500
Subject: [PATCH 22/27] Use more familiar time point comparison syntax

---
 src/libmongoc/src/mongoc/mongoc-stream-tls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-tls.c b/src/libmongoc/src/mongoc/mongoc-stream-tls.c
index 4a5ad7f666e..52c39312816 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-tls.c
+++ b/src/libmongoc/src/mongoc/mongoc-stream-tls.c
@@ -254,7 +254,7 @@ _mongoc_stream_tls_timer_to_timeout_msec(mlib_timer timer)
 {
    const mlib_timer never = mlib_expires_never();
 
-   if (mlib_time_cmp(timer.expires_at, never.expires_at) == mlib_equal) {
+   if (mlib_time_cmp(timer.expires_at, ==, never.expires_at)) {
       return MONGOC_SOCKET_TIMEOUT_INFINITE;
    }
 

From f65bb766aac51a2cdd21baf28d30f14d58d67e16 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 08:58:54 -0500
Subject: [PATCH 23/27] Move new constants into private header

---
 src/libmongoc/src/mongoc/mongoc-stream-private.h | 3 +++
 src/libmongoc/src/mongoc/mongoc-stream.h         | 3 ---
 src/libmongoc/src/mongoc/mongoc-uri.c            | 1 +
 src/libmongoc/tests/test-mongoc-uri.c            | 1 +
 4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-private.h b/src/libmongoc/src/mongoc/mongoc-stream-private.h
index 66a50e75627..adfddb9a1a1 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream-private.h
@@ -39,6 +39,9 @@ BSON_BEGIN_DECLS
 #define MONGOC_STREAM_GRIDFS_UPLOAD 6
 #define MONGOC_STREAM_GRIDFS_DOWNLOAD 7
 
+#define MONGOC_SOCKET_TIMEOUT_INFINITE 0
+#define MONGOC_SOCKET_TIMEOUT_IMMEDIATE INT32_MIN
+
 bool
 mongoc_stream_wait(mongoc_stream_t *stream, int64_t expire_at);
 
diff --git a/src/libmongoc/src/mongoc/mongoc-stream.h b/src/libmongoc/src/mongoc/mongoc-stream.h
index 07058787af8..de8901712d4 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream.h
@@ -29,9 +29,6 @@
 BSON_BEGIN_DECLS
 
 
-#define MONGOC_SOCKET_TIMEOUT_INFINITE 0
-#define MONGOC_SOCKET_TIMEOUT_IMMEDIATE INT32_MIN
-
 typedef struct _mongoc_stream_t mongoc_stream_t;
 
 typedef struct _mongoc_stream_poll_t {
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index aa9c4004df4..e16eaec1639 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -31,6 +31,7 @@
 #include <mongoc/mongoc-host-list-private.h>
 #include <mongoc/mongoc-oidc-env-private.h>
 #include <mongoc/mongoc-read-concern-private.h>
+#include <mongoc/mongoc-stream-private.h>
 #include <mongoc/mongoc-topology-private.h>
 #include <mongoc/mongoc-trace-private.h>
 #include <mongoc/mongoc-uri-private.h>
diff --git a/src/libmongoc/tests/test-mongoc-uri.c b/src/libmongoc/tests/test-mongoc-uri.c
index 84f133ff966..24dc34e7be9 100644
--- a/src/libmongoc/tests/test-mongoc-uri.c
+++ b/src/libmongoc/tests/test-mongoc-uri.c
@@ -1,6 +1,7 @@
 #include <common-string-private.h>
 #include <mongoc/mongoc-client-private.h>
 #include <mongoc/mongoc-host-list-private.h>
+#include <mongoc/mongoc-stream-private.h>
 #include <mongoc/mongoc-topology-private.h>
 #include <mongoc/mongoc-uri-private.h>
 #include <mongoc/mongoc-util-private.h>

From fb8f40fa96decbdf1a345a799ed23eced72f5b50 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 09:04:47 -0500
Subject: [PATCH 24/27] Fix inconsistent integer widths

---
 src/libmongoc/src/mongoc/mongoc-uri.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index e16eaec1639..6036a5e107a 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2616,6 +2616,8 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
       return MONGOC_SOCKET_TIMEOUT_INFINITE;
    }
 
+   const int32_t fallback = MONGOC_DEFAULT_SOCKETTIMEOUTMS;
+
    const bson_t *const options = mongoc_uri_get_options(uri);
    bson_iter_t iter;
 
@@ -2625,16 +2627,16 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
 
       if (value == 0) {
          // See CDRIVER-6177.
-         MONGOC_WARNING("`socketTimeoutMS=0` cannot be used to disable socket timeouts. The default of %" PRId64
+         MONGOC_WARNING("`socketTimeoutMS=0` cannot be used to disable socket timeouts. The default of %" PRId32
                         " will be used instead. To disable socket timeouts, use `socketTimeoutMS=inf`.",
-                        (int64_t)MONGOC_DEFAULT_SOCKETTIMEOUTMS);
-         return MONGOC_DEFAULT_SOCKETTIMEOUTMS;
+                        fallback);
+         return fallback;
       } else {
          return value;
       }
    }
 
-   return MONGOC_DEFAULT_SOCKETTIMEOUTMS;
+   return fallback;
 }
 
 const char *

From 1773b8a32fe1882362089c83a77a121f8265c22d Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 09:05:29 -0500
Subject: [PATCH 25/27] Fix inconsistent east/west const

---
 src/libmongoc/src/mongoc/mongoc-uri.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 6036a5e107a..8f9cf697d87 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -2623,7 +2623,7 @@ mongoc_uri_get_socket_timeout_ms_option(const mongoc_uri_t *uri)
 
    if (options && bson_iter_init_find_case(&iter, options, MONGOC_URI_SOCKETTIMEOUTMS) &&
        BSON_ITER_HOLDS_INT32(&iter)) {
-      int32_t const value = bson_iter_int32(&iter);
+      const int32_t value = bson_iter_int32(&iter);
 
       if (value == 0) {
          // See CDRIVER-6177.

From 5314d229adcff33464162dd678d10b89238a20a9 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 09:17:59 -0500
Subject: [PATCH 26/27] Move MONGOC_DEFAULT_SOCKETTIMEOUTMS back to
 mongoc-client.h

---
 src/libmongoc/src/mongoc/mongoc-client.h | 15 +++++++++++++++
 src/libmongoc/src/mongoc/mongoc-uri.c    |  2 ++
 src/libmongoc/src/mongoc/mongoc-uri.h    | 14 --------------
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-client.h b/src/libmongoc/src/mongoc/mongoc-client.h
index 3c89c0e70a4..55b74d0f610 100644
--- a/src/libmongoc/src/mongoc/mongoc-client.h
+++ b/src/libmongoc/src/mongoc/mongoc-client.h
@@ -54,6 +54,21 @@ BSON_BEGIN_DECLS
 #endif
 
 
+#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
+/*
+ * NOTE: The default socket timeout for connections is 5 minutes. This
+ *       means that if your MongoDB server dies or becomes unavailable
+ *       it will take 5 minutes to detect this.
+ *
+ *       You can change this by providing sockettimeoutms= in your
+ *       connection URI.
+ *
+ *       CDRIVER-6177: This default is not spec compliant.
+ */
+#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
+#endif
+
+
 /**
  * mongoc_client_t:
  *
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 8f9cf697d87..965d54f14d6 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -38,6 +38,8 @@
 #include <mongoc/mongoc-util-private.h>
 #include <mongoc/mongoc-write-concern-private.h>
 
+// CDRIVER-6179: Including mongoc-client.h for MONGOC_DEFAULT_SOCKETTIMEOUTMS.
+#include <mongoc/mongoc-client.h>
 #include <mongoc/mongoc-config.h>
 #include <mongoc/mongoc-host-list.h>
 #include <mongoc/mongoc-log.h>
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.h b/src/libmongoc/src/mongoc/mongoc-uri.h
index bd87243fb24..ecf689d6ae7 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.h
+++ b/src/libmongoc/src/mongoc/mongoc-uri.h
@@ -33,20 +33,6 @@
 #define MONGOC_DEFAULT_PORT 27017
 #endif
 
-#ifndef MONGOC_DEFAULT_SOCKETTIMEOUTMS
-/*
- * NOTE: The default socket timeout for connections is 5 minutes. This
- *       means that if your MongoDB server dies or becomes unavailable
- *       it will take 5 minutes to detect this.
- *
- *       You can change this by providing sockettimeoutms= in your
- *       connection URI.
- *
- *       CDRIVER-6177: This default is not spec compliant.
- */
-#define MONGOC_DEFAULT_SOCKETTIMEOUTMS (1000L * 60L * 5L)
-#endif
-
 #define MONGOC_URI_APPNAME "appname"
 #define MONGOC_URI_AUTHMECHANISM "authmechanism"
 #define MONGOC_URI_AUTHMECHANISMPROPERTIES "authmechanismproperties"

From 4b7dce8fef62172cdafbc824e90546cfcea544e8 Mon Sep 17 00:00:00 2001
From: Connor MacDonald <connor.macdonald@mongodb.com>
Date: Thu, 18 Dec 2025 09:23:10 -0500
Subject: [PATCH 27/27] Fix fixed-width integer includes

---
 src/libmongoc/src/mongoc/mongoc-stream-private.h | 2 ++
 src/libmongoc/src/mongoc/mongoc-stream.h         | 2 --
 src/libmongoc/src/mongoc/mongoc-uri.c            | 2 ++
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libmongoc/src/mongoc/mongoc-stream-private.h b/src/libmongoc/src/mongoc/mongoc-stream-private.h
index adfddb9a1a1..9fd71ccf575 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream-private.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream-private.h
@@ -27,6 +27,8 @@
 
 #include <mlib/timer.h>
 
+#include <stdint.h>
+
 
 BSON_BEGIN_DECLS
 
diff --git a/src/libmongoc/src/mongoc/mongoc-stream.h b/src/libmongoc/src/mongoc/mongoc-stream.h
index de8901712d4..723f5febd43 100644
--- a/src/libmongoc/src/mongoc/mongoc-stream.h
+++ b/src/libmongoc/src/mongoc/mongoc-stream.h
@@ -23,8 +23,6 @@
 #include <mongoc/mongoc-macros.h>
 #include <mongoc/mongoc-socket.h>
 
-#include <stdint.h>
-
 
 BSON_BEGIN_DECLS
 
diff --git a/src/libmongoc/src/mongoc/mongoc-uri.c b/src/libmongoc/src/mongoc/mongoc-uri.c
index 965d54f14d6..70fc4a3284b 100644
--- a/src/libmongoc/src/mongoc/mongoc-uri.c
+++ b/src/libmongoc/src/mongoc/mongoc-uri.c
@@ -18,7 +18,9 @@
 #include <sys/types.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <math.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>