Adding a constant for a well known place where the SSL roots are installed.

include/grpc/grpc_security.h

@@ -73,8 +73,11 @@ typedef struct {
 
 /* Creates an SSL credentials object.
    - pem_roots_cert is the NULL-terminated string containing the PEM encoding
-     of the server root certificates. If this parameter is NULL, the default
-     roots will be used.
+     of the server root certificates. If this parameter is NULL, the
+     implementation will first try to dereference the file pointed by the
+     GRPC_DEFAULT_SSL_ROOTS_FILE_PATH environment variable, and if that fails,
+     will try to dereference the GRPC_SSL_ROOTS_WELL_KNOWN_PATH defined in
+     ssl_roots.h (which value is patched during the grpc Install process).
    - pem_key_cert_pair is a pointer on the object containing client's private
      key and certificate chain. This parameter can be NULL if the client does
      not have such a key/cert pair.  */

src/core/security/security_context.c

@@ -39,6 +39,7 @@
 #include "src/core/channel/http_client_filter.h"
 #include "src/core/security/credentials.h"
 #include "src/core/security/secure_endpoint.h"
+#include "src/core/security/ssl_roots.h"
 #include "src/core/support/env.h"
 #include "src/core/support/file.h"
 #include "src/core/support/string.h"
@@ -403,6 +404,10 @@ static void init_default_pem_root_certs(void) {
   } else {
     default_pem_root_certs = gpr_load_file(default_root_certs_path, NULL);
     gpr_free(default_root_certs_path);
+    if (GPR_SLICE_IS_EMPTY(default_pem_root_certs)) {
+      default_pem_root_certs =
+          gpr_load_file(GRPC_SSL_ROOTS_WELL_KNOWN_PATH, NULL);
+    }
   }
 }
 

src/core/security/ssl_roots.h

@@ -0,0 +1,40 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef __GRPC_INTERNAL_SECURITY_SSL_ROOTS_H__
+#define __GRPC_INTERNAL_SECURITY_SSL_ROOTS_H__
+
+/* WARNING: this value is patched at install time. */
+#define GRPC_SSL_ROOTS_WELL_KNOWN_PATH "/etc/grpc/roots.pem"
+
+#endif /* __GRPC_INTERNAL_SECURITY_SSL_ROOTS_H__ */