Extend coap_tls_version_t to include both built and runtime TLS versions

This allows an application to determine what the built version is
as well as what the runtime version of a TLS library is.

include/coap2/coap_dtls.h

Add built_version to coap_tls_version_t

src/coap_openssl.c
src/coap_tinydtls.c

Additionally populate coap_tls_version_t with build_version when
coap_get_tls_library_version() is called.

src/coap_tinydtls.c

Correct the version returned as actual TinyDTLS version instead the
binary value of a DTLS packet type.

include/coap2/coap_dtls.h

@@ -45,8 +45,9 @@ int coap_tls_is_supported(void);
  * information.
  */
 typedef struct coap_tls_version_t {
-  uint64_t version; /**< (D)TLS Library Version */
+  uint64_t version; /**< (D)TLS runtime Library Version */
   int type; /**< Library type. One of COAP_TLS_LIBRARY_* */
+  uint64_t built_version; /**< (D)TLS Built against Library Version */
 } coap_tls_version_t;
 
 /**

src/coap_openssl.c

@@ -142,6 +142,7 @@ coap_tls_version_t *
 coap_get_tls_library_version(void) {
   static coap_tls_version_t version;
   version.version = SSLeay();
+  version.built_version = OPENSSL_VERSION_NUMBER;
   version.type = COAP_TLS_LIBRARY_OPENSSL;
   return &version;
 }

src/coap_tinydtls.c

@@ -453,7 +453,23 @@ int coap_tls_is_supported(void) {
 coap_tls_version_t *
 coap_get_tls_library_version(void) {
   static coap_tls_version_t version;
-  version.version = DTLS_VERSION;
+  const char *vers = dtls_package_version();
+
+  version.version = 0;
+  if (vers) {
+    long int p1, p2 = 0, p3 = 0;
+    char* endptr;
+
+    p1 = strtol(vers, &endptr, 10);
+    if (*endptr == '.') {
+      p2 = strtol(endptr+1, &endptr, 10);
+      if (*endptr == '.') {
+        p3 = strtol(endptr+1, &endptr, 10);
+      }
+    }
+    version.version = (p1 << 16) | (p2 << 8) | p3;
+  }
+  version.built_version = version.version;
   version.type = COAP_TLS_LIBRARY_TINYDTLS;
   return &version;
 }