Subject: [PATCH v5] contrib/sslinfo: Add ssl_group_info

From: Dmitrii Dolgov <[email-masked]>
Date: Thu, 19 Feb 2026 16:33:17 +0100

Add a new function to sslinfo ssl_group_info to show SSL groups,
including negotiated, supported and shared. It's useful for diagnostic
purposes, to identify what's being used and supported, e.g. which key
share is being negotiated. Few examples, for openssl 3.2.4:

    select * from ssl_group_info();
	type    |        name
    ------------+--------------------
     negotiated | X25519MLKEM768
     shared     | X25519MLKEM768
     shared     | x25519
     supported  | X25519MLKEM768
     supported  | x25519
     [...]

The implementation is inspired by ssl_print_groups from openssl.
---
 configure                             |  36 +++++
 configure.ac                          |   4 +
 contrib/sslinfo/Makefile              |   2 +-
 contrib/sslinfo/meson.build           |   1 +
 contrib/sslinfo/sslinfo--1.2--1.3.sql |  10 ++
 contrib/sslinfo/sslinfo.c             | 189 +++++++++++++++++++++++++-
 contrib/sslinfo/sslinfo.control       |   2 +-
 doc/src/sgml/sslinfo.sgml             |  45 ++++++
 meson.build                           |   5 +
 src/include/pg_config.h.in            |  11 ++
 src/tools/pgindent/typedefs.list      |   1 +
 11 files changed, 303 insertions(+), 3 deletions(-)
 create mode 100644 contrib/sslinfo/sslinfo--1.2--1.3.sql

diff --git a/configure b/configure
index 5aec0afa9ab..b867c188ffc 100755
--- a/configure
+++ b/configure
@@ -13189,6 +13189,42 @@ _ACEOF
 fi
 done
 
+  # Functions for groups support, some of them are real functions, some are
+  # just wrappers around SSL_ctrl.
+  for ac_func in SSL_group_to_name
+do :
+  ac_fn_c_check_func "$LINENO" "SSL_group_to_name" "ac_cv_func_SSL_group_to_name"
+if test "x$ac_cv_func_SSL_group_to_name" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_SSL_GROUP_TO_NAME 1
+_ACEOF
+
+fi
+done
+
+ac_fn_c_check_decl "$LINENO" "SSL_get1_groups" "ac_cv_have_decl_SSL_get1_groups" "#include <openssl/ssl.h>
+"
+if test "x$ac_cv_have_decl_SSL_get1_groups" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_SSL_GET1_GROUPS $ac_have_decl
+_ACEOF
+ac_fn_c_check_decl "$LINENO" "SSL_get_negotiated_group" "ac_cv_have_decl_SSL_get_negotiated_group" "#include <openssl/ssl.h>
+"
+if test "x$ac_cv_have_decl_SSL_get_negotiated_group" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_SSL_GET_NEGOTIATED_GROUP $ac_have_decl
+_ACEOF
+
 
 $as_echo "#define USE_OPENSSL 1" >>confdefs.h
 
diff --git a/configure.ac b/configure.ac
index fead9a6ce99..6b3bd8667bc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1444,6 +1444,10 @@ if test "$with_ssl" = openssl ; then
   AC_CHECK_FUNCS([SSL_CTX_set_cert_cb])
   # Function introduced in OpenSSL 1.1.1, not in LibreSSL.
   AC_CHECK_FUNCS([X509_get_signature_info SSL_CTX_set_num_tickets SSL_CTX_set_keylog_callback])
+  # Functions for groups support, some of them are real functions, some are
+  # just wrappers around SSL_ctrl.
+  AC_CHECK_FUNCS([SSL_group_to_name])
+  AC_CHECK_DECLS([SSL_get1_groups, SSL_get_negotiated_group], [], [], [#include <openssl/ssl.h>])
   AC_DEFINE([USE_OPENSSL], 1, [Define to 1 to build with OpenSSL support. (--with-ssl=openssl)])
 elif test "$with_ssl" != no ; then
   AC_MSG_ERROR([--with-ssl must specify openssl])
diff --git a/contrib/sslinfo/Makefile b/contrib/sslinfo/Makefile
index 14305594e2d..d968ef2abfd 100644
--- a/contrib/sslinfo/Makefile
+++ b/contrib/sslinfo/Makefile
@@ -6,7 +6,7 @@ OBJS = \
 	sslinfo.o
 
 EXTENSION = sslinfo
-DATA = sslinfo--1.2.sql sslinfo--1.1--1.2.sql sslinfo--1.0--1.1.sql
+DATA = sslinfo--1.2.sql sslinfo--1.2--1.3.sql sslinfo--1.1--1.2.sql sslinfo--1.0--1.1.sql
 PGFILEDESC = "sslinfo - information about client SSL certificate"
 
 ifdef USE_PGXS
diff --git a/contrib/sslinfo/meson.build b/contrib/sslinfo/meson.build
index 6e9cb96430a..27737562925 100644
--- a/contrib/sslinfo/meson.build
+++ b/contrib/sslinfo/meson.build
@@ -26,6 +26,7 @@ install_data(
   'sslinfo--1.0--1.1.sql',
   'sslinfo--1.1--1.2.sql',
   'sslinfo--1.2.sql',
+  'sslinfo--1.2--1.3.sql',
   'sslinfo.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/sslinfo/sslinfo--1.2--1.3.sql b/contrib/sslinfo/sslinfo--1.2--1.3.sql
new file mode 100644
index 00000000000..40fd0ea2b9c
--- /dev/null
+++ b/contrib/sslinfo/sslinfo--1.2--1.3.sql
@@ -0,0 +1,10 @@
+/* contrib/sslinfo/sslinfo--1.2--1.3.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION sslinfo UPDATE TO '1.3'" to load this file. \quit
+
+CREATE FUNCTION
+ssl_group_info(OUT group_type text, OUT name text
+) RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'ssl_group_info'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
diff --git a/contrib/sslinfo/sslinfo.c b/contrib/sslinfo/sslinfo.c
index 2b9eb90b093..d3f50bc03bf 100644
--- a/contrib/sslinfo/sslinfo.c
+++ b/contrib/sslinfo/sslinfo.c
@@ -19,6 +19,11 @@
 #include "miscadmin.h"
 #include "utils/builtins.h"
 
+#define HAVE_SSL_GROUPS \
+	defined(HAVE_DECL_SSL_GET1_GROUPS) && \
+	defined(HAVE_DECL_SSL_GET_NEGOTIATED_GROUP) && \
+	defined(HAVE_SSL_GROUP_TO_NAME)
+
 PG_MODULE_MAGIC_EXT(
 					.name = "sslinfo",
 					.version = PG_VERSION
@@ -28,13 +33,28 @@ static Datum X509_NAME_field_to_text(X509_NAME *name, text *fieldName);
 static Datum ASN1_STRING_to_text(ASN1_STRING *str);
 
 /*
- * Function context for data persisting over repeated calls.
+ * Function context for data persisting over repeated calls of
+ * ssl_extension_info.
  */
 typedef struct
 {
 	TupleDesc	tupdesc;
 } SSLExtensionInfoContext;
 
+/*
+ * Function context for data persisting over repeated calls of
+ * ssl_group_info.
+ */
+typedef struct
+{
+	TupleDesc	tupdesc;
+	int			nshared;
+	int			nsupported;
+
+	/* Supported groups have to be stored separately */
+	int		   *supported_groups;
+} SSLGroupInfoContext;
+
 /*
  * Indicates whether current session uses SSL
  *
@@ -474,3 +494,170 @@ ssl_extension_info(PG_FUNCTION_ARGS)
 	/* All done */
 	SRF_RETURN_DONE(funcctx);
 }
+
+/*
+ * Returns information about TLS groups.
+ *
+ * Returns setof record made of the following values:
+ * - type of the group: negotiated, shared, supported.
+ * - name of the group.
+ */
+PG_FUNCTION_INFO_V1(ssl_group_info);
+Datum
+ssl_group_info(PG_FUNCTION_ARGS)
+{
+#if HAVE_SSL_GROUPS
+	/*
+	 * If we lack SSL groups API, we still need to do SRF stuff. Thus the
+	 * condition doesn't cover the whole function, but only parts of it. This
+	 * particular one is only to avoid unused variable warning, in case if
+	 * HAVE_SSL_GROUPS is false.
+	 */
+	SSL		   *ssl = MyProcPort->ssl;
+#endif
+
+	FuncCallContext *funcctx;
+	int			call_cntr = 0;
+	int			max_calls = 0;
+	MemoryContext oldcontext;
+	SSLGroupInfoContext *fctx;
+
+	if (SRF_IS_FIRSTCALL())
+	{
+
+		TupleDesc	tupdesc;
+
+		/* create a function context for cross-call persistence */
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		/*
+		 * Switch to memory context appropriate for multiple function calls
+		 */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		/* Create a user function context for cross-call persistence */
+		fctx = palloc_object(SSLGroupInfoContext);
+
+		/* Construct tuple descriptor */
+		if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("function returning record called in context that cannot accept type record")));
+		fctx->tupdesc = BlessTupleDesc(tupdesc);
+
+		if (!MyProcPort->ssl_in_use)
+		{
+			/* fast track when no results */
+			MemoryContextSwitchTo(oldcontext);
+			SRF_RETURN_DONE(funcctx);
+		}
+
+#if HAVE_SSL_GROUPS
+		if (ssl != NULL)
+		{
+			fctx->nsupported = SSL_get1_groups(ssl, NULL);
+			fctx->nshared = SSL_get_shared_group(ssl, -1);
+
+			fctx->supported_groups =
+				palloc(fctx->nsupported * sizeof(*fctx->supported_groups));
+			SSL_get1_groups(ssl, fctx->supported_groups);
+
+			/*
+			 * Set max_calls as the number of supported groups plus the number
+			 * of shared groups plus one negotiated group.
+			 */
+			max_calls = fctx->nsupported + fctx->nshared + 1;
+		}
+
+		if (max_calls > 0)
+		{
+			/* got results, keep track of them */
+			funcctx->max_calls = max_calls;
+			funcctx->user_fctx = fctx;
+		}
+		else
+		{
+			/* fast track when no results */
+			MemoryContextSwitchTo(oldcontext);
+			SRF_RETURN_DONE(funcctx);
+		}
+#else
+		/* SSL groups API is not present, skip */
+		MemoryContextSwitchTo(oldcontext);
+		SRF_RETURN_DONE(funcctx);
+#endif
+
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	/* stuff done on every call of the function */
+	funcctx = SRF_PERCALL_SETUP();
+
+	/*
+	 * Initialize per-call variables.
+	 */
+	call_cntr = funcctx->call_cntr;
+	max_calls = funcctx->max_calls;
+	fctx = funcctx->user_fctx;
+
+	/* do while there are more left to send */
+	if (call_cntr < max_calls)
+	{
+#if HAVE_SSL_GROUPS
+		Datum		values[2];
+		bool		nulls[2];
+		HeapTuple	tuple;
+		Datum		result,
+					group_type;
+		int			nid;
+		const char *group_name;
+
+		/* Send the negotiated group first */
+		if (call_cntr == 0)
+		{
+			nid = SSL_get_negotiated_group(ssl);
+			group_type = CStringGetTextDatum("negotiated");
+		}
+		/* Then the shared groups */
+		else if (call_cntr < fctx->nshared + 1)
+		{
+			nid = SSL_get_shared_group(ssl, call_cntr - 1);
+			group_type = CStringGetTextDatum("shared");
+		}
+		/* And finally the supported groups */
+		else if (call_cntr < fctx->nsupported + fctx->nshared + 1)
+		{
+			nid = fctx->supported_groups[call_cntr - fctx->nshared - 1];
+			group_type = CStringGetTextDatum("supported");
+		}
+		else
+			SRF_RETURN_DONE(funcctx);
+
+		/*
+		 * SSL_group_to_name can return NULL in case of an error, e.g. when no
+		 * such name was registered for some reason.
+		 */
+		group_name = SSL_group_to_name(ssl, nid);
+		if (group_name == NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("unknown OpenSSL group at position %d",
+							call_cntr)));
+
+		values[0] = group_type;
+		nulls[0] = false;
+
+		values[1] = CStringGetTextDatum(group_name);
+		nulls[1] = false;
+
+		/* Build tuple */
+		tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
+		result = HeapTupleGetDatum(tuple);
+
+		SRF_RETURN_NEXT(funcctx, result);
+#endif
+	}
+
+	/* All done */
+	SRF_RETURN_DONE(funcctx);
+}
diff --git a/contrib/sslinfo/sslinfo.control b/contrib/sslinfo/sslinfo.control
index c7754f924cf..b53e95b7da8 100644
--- a/contrib/sslinfo/sslinfo.control
+++ b/contrib/sslinfo/sslinfo.control
@@ -1,5 +1,5 @@
 # sslinfo extension
 comment = 'information about SSL certificates'
-default_version = '1.2'
+default_version = '1.3'
 module_pathname = '$libdir/sslinfo'
 relocatable = true
diff --git a/doc/src/sgml/sslinfo.sgml b/doc/src/sgml/sslinfo.sgml
index 85d49f66537..422745de37c 100644
--- a/doc/src/sgml/sslinfo.sgml
+++ b/doc/src/sgml/sslinfo.sgml
@@ -240,6 +240,51 @@ emailAddress
     </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>ssl_group_info() returns setof record</function>
+     <indexterm>
+      <primary>ssl_group_info</primary>
+     </indexterm>
+    </term>
+    <listitem>
+    <para>
+     Provide information about TLS groups: group type and group name.
+     The group type value could be one of the following:
+
+     <variablelist>
+      <varlistentry id="ssl-group-info-negotiated">
+       <term><literal>negotiated</literal></term>
+       <listitem>
+        <para>
+         The group used for the handshake key exchange process.
+        </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry id="ssl-group-info-shared">
+       <term><literal>shared</literal></term>
+       <listitem>
+        <para>
+         Lisf of named groups shared with the server side.
+        </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry id="ssl-group-info-supported">
+       <term><literal>supported</literal></term>
+       <listitem>
+        <para>
+         list of named groups supported by the client for key exchange in the
+         form of "supported_groups" extension.
+        </para>
+       </listitem>
+      </varlistentry>
+     </variablelist>
+    </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </sect2>
 
diff --git a/meson.build b/meson.build
index 7ee900198db..944db2610b4 100644
--- a/meson.build
+++ b/meson.build
@@ -1684,6 +1684,9 @@ if sslopt in ['auto', 'openssl']
       ['X509_get_signature_info'],
       ['SSL_CTX_set_num_tickets'],
       ['SSL_CTX_set_keylog_callback'],
+
+      # Function for groups support.
+      ['SSL_group_to_name'],
     ]
 
     are_openssl_funcs_complete = true
@@ -2793,6 +2796,8 @@ decl_checks = [
   ['strlcpy', 'string.h'],
   ['strsep',  'string.h'],
   ['timingsafe_bcmp',  'string.h'],
+  ['SSL_get1_groups',           'openssl/ssl.h'],
+  ['SSL_get_negotiated_group',  'openssl/ssl.h'],
 ]
 
 # Need to check for function declarations for these functions, because
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 79379a4d125..a59373ae7ad 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -101,6 +101,14 @@
    don't. */
 #undef HAVE_DECL_PWRITEV
 
+/* Define to 1 if you have the declaration of `SSL_get1_groups', and to 0 if
+   you don't. */
+#undef HAVE_DECL_SSL_GET1_GROUPS
+
+/* Define to 1 if you have the declaration of `SSL_get_negotiated_group', and
+   to 0 if you don't. */
+#undef HAVE_DECL_SSL_GET_NEGOTIATED_GROUP
+
 /* Define to 1 if you have the declaration of `strchrnul', and to 0 if you
    don't. */
 #undef HAVE_DECL_STRCHRNUL
@@ -378,6 +386,9 @@
 /* Define to 1 if you have the `SSL_CTX_set_num_tickets' function. */
 #undef HAVE_SSL_CTX_SET_NUM_TICKETS
 
+/* Define to 1 if you have the `SSL_group_to_name' function. */
+#undef HAVE_SSL_GROUP_TO_NAME
+
 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H
 
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 52f8603a7be..b5ea3c18291 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2720,6 +2720,7 @@ SQLValueFunction
 SQLValueFunctionOp
 SSL
 SSLExtensionInfoContext
+SSLGroupInfoContext
 SSL_CTX
 STARTUPINFO
 STRLEN

base-commit: e82fc27e095b5a84c578b6e6b43b3396463bd812
-- 
2.52.0

--zwjbi4ijbttgewfx--