[Buildroot] [git commit branch/2020.02.x] package/libcoap: properly enable DTLS support

[Peter Korsgaard]

commit: https://git.buildroot.net/buildroot/commit/?id=e8bcc7735b000634c85861c4dcc69a5bbf616749
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2020.02.x

The DTLS support needs either gnutls or openssl, so let's have these
packages as optional dependencies. We prefer gnutls over openssl as
done by upstream in their configure.ac when the user does not provide
any option (which is the case currently)

While there is support for tinydtls, and Buildroot has a tinydtls
package, libcoap is only able to use its own internal library, and
only when static linking is enabled, so we simply disable the use of
tinydtls altogether.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
(cherry picked from commit 8b14f6b49b962d4d8f7135d85afa15658ea8f94b)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 package/libcoap/libcoap.mk | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/package/libcoap/libcoap.mk b/package/libcoap/libcoap.mk
index e2fbaa3dfb..bea0e68889 100644
--- a/package/libcoap/libcoap.mk
+++ b/package/libcoap/libcoap.mk
@@ -10,7 +10,17 @@ LIBCOAP_INSTALL_STAGING = YES
 LIBCOAP_LICENSE = BSD-2-Clause
 LIBCOAP_LICENSE_FILES = COPYING LICENSE
 LIBCOAP_DEPENDENCIES = host-pkgconf
-LIBCOAP_CONF_OPTS = --disable-examples
+LIBCOAP_CONF_OPTS = --disable-examples --without-tinydtls
 LIBCOAP_AUTORECONF = YES
 
+ifeq ($(BR2_PACKAGE_GNUTLS),y)
+LIBCOAP_DEPENDENCIES += gnutls
+LIBCOAP_CONF_OPTS += --enable-dtls --with-gnutls --without-openssl
+else ifeq ($(BR2_PACKAGE_OPENSSL),y)
+LIBCOAP_DEPENDENCIES += openssl
+LIBCOAP_CONF_OPTS += --enable-dtls --without-gnutls --with-openssl
+else
+LIBCOAP_CONF_OPTS += --disable-dtls
+endif
+
 $(eval $(autotools-package))