[PATCH v1] Mbed TLS: Error out if we have no valid tls-groups

From: Max Fillinger <[email protected]>

Previously, when no valid groups were specified with the tls-groups
option, the Mbed TLS build of OpenVPN would start up and run, but fail
to complete a handshake, while the OpenSSL build would exit with an
error. This commit changes the behavior of the Mbed TLS build to match
the OpenSSL version.

Change-Id: Ica5f37e525c3812609021750ecd3986c1420e2a4
Signed-off-by: Max Fillinger <[email protected]>
Acked-by: Arne Schwabe <[email protected]>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1633
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1633
This mail reflects revision 1 of this Change.

Acked-by according to Gerrit (reflected above):
Arne Schwabe <[email protected]>

        
diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index 85c771a..8a0f7d2 100644
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -450,6 +450,12 @@
         }
     }
 
+    /* Check if any groups were valid. */
+    if (i == 0)
+    {
+        msg(M_FATAL, "Error: All groups in \"%s\" are invalid or unsupported.", groups);
+    }
+
     /* Recent mbedtls versions state that the list of groups must be terminated
      * with 0. Older versions state that it must be terminated with MBEDTLS_ECP_DP_NONE
      * which is also 0, so this works either way. */