Subject: [PATCH v3] 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.
---
 contrib/sslinfo/Makefile              |   2 +-
 contrib/sslinfo/meson.build           |   2 +-
 contrib/sslinfo/sslinfo--1.2--1.3.sql |  10 ++
 contrib/sslinfo/sslinfo.c             | 167 +++++++++++++++++++++++++-
 contrib/sslinfo/sslinfo.control       |   2 +-
 doc/src/sgml/sslinfo.sgml             |  45 +++++++
 src/tools/pgindent/typedefs.list      |   1 +
 7 files changed, 225 insertions(+), 4 deletions(-)
 create mode 100644 contrib/sslinfo/sslinfo--1.2--1.3.sql

diff --git a/contrib/sslinfo/Makefile b/contrib/sslinfo/Makefile
index 14305594e2d..dc837209c93 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--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..29c7da44228 100644
--- a/contrib/sslinfo/meson.build
+++ b/contrib/sslinfo/meson.build
@@ -25,7 +25,7 @@ contrib_targets += sslinfo
 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..e018010d4be 100644
--- a/contrib/sslinfo/sslinfo.c
+++ b/contrib/sslinfo/sslinfo.c
@@ -28,13 +28,28 @@ 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 +489,153 @@ 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)
+{
+	SSL		   *ssl = MyProcPort->ssl;
+	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 (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);
+		}
+
+		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)
+	{
+		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);
+	}
+
+	/* 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/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

--fucpmbwjcehrmjf7--