From 56ba1b99dba784b2bf4963482828d1d3881ca768 Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Thu, 10 Sep 2020 15:50:47 +0100
Subject: [PATCH] Add `mosquitto_ssl_get()`.

This allow clients to access their SSL structure and
perform additional verification.
---
 ChangeLog.txt      |  2 ++
 lib/linker.version |  1 +
 lib/mosquitto.h    | 17 +++++++++++++++++
 lib/net_mosq.c     | 11 +++++++++++
 4 files changed, 31 insertions(+)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index 8049484f..862271b9 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -37,6 +37,8 @@ Client library:
   setting the retain bit.
 - Added MOSQ_OPT_TCP_NODELAY, to allow disabling Nagle's algorithm on client
   sockets. Closes #1526.
+- Add `mosquitto_ssl_get()` to allow clients to access their SSL structure and
+  perform additional verification.
 
 Clients:
 - Add timeout return code (27) for `mosquitto_sub -W <secs>` and
diff --git a/lib/linker.version b/lib/linker.version
index ea9bd04b..67902fc6 100644
--- a/lib/linker.version
+++ b/lib/linker.version
@@ -138,4 +138,5 @@ MOSQ_1.7 {
 		mosquitto_property_identifier;
 		mosquitto_property_identifier_to_string;
 		mosquitto_property_next;
+		mosquitto_ssl_get;
 } MOSQ_1.6;
diff --git a/lib/mosquitto.h b/lib/mosquitto.h
index 2d770046..be1b8333 100644
--- a/lib/mosquitto.h
+++ b/lib/mosquitto.h
@@ -1743,6 +1743,23 @@ libmosq_EXPORT int mosquitto_tls_opts_set(struct mosquitto *mosq, int cert_reqs,
 libmosq_EXPORT int mosquitto_tls_psk_set(struct mosquitto *mosq, const char *psk, const char *identity, const char *ciphers);
 
 
+/*
+ * Function: mosquitto_ssl_get
+ *
+ * Retrieve a pointer to the SSL structure used for TLS connections in this
+ * client. This can be used in e.g. the connect callback to carry out
+ * additional verification steps.
+ *
+ * Parameters:
+ *  mosq - a valid mosquitto instance
+ *
+ * Returns:
+ *  A valid pointer to an openssl SSL structure - if the client is using TLS.
+ *  NULL - if the client is not using TLS, or TLS support is not compiled in.
+ */
+libmosq_EXPORT void *mosquitto_ssl_get(struct mosquitto *mosq);
+
+
 /* ======================================================================
  *
  * Section: Callbacks
diff --git a/lib/net_mosq.c b/lib/net_mosq.c
index 72e7b096..6dbe8992 100644
--- a/lib/net_mosq.c
+++ b/lib/net_mosq.c
@@ -1174,3 +1174,14 @@ int net__socketpair(mosq_sock_t *pairR, mosq_sock_t *pairW)
 #endif
 }
 #endif
+
+#ifndef WITH_BROKER
+void *mosquitto_ssl_get(struct mosquitto *mosq)
+{
+#ifdef WITH_TLS
+	return mosq->ssl;
+#else
+	return NULL;
+#endif
+}
+#endif