Clean up private key file error reporting.

Ensure that rsa_load_pem_key() and rsa_load_pkcs12() always return an
error message string if they fail, so that

	1) they don't return NULL without supplying an error string;

	2) they don't supply an error string if they succeed.

If either of them fails, report the error; if there's no error string,
report an unknown error (that shouldn't happen, but the wsutil/rsa.c
code needs more cleanup before I'll believe it can't happen).

While we're at it, clean up some of those error strings, return NULL
rather than 0 as the failure case from rsa_load_pkcs12() as we do in
rsa_load_pem_key() (they mean the same thing, but NULL makes it a bit
clearer), and de-initialize the private key structure in
rsa_load_pem_key() if we fail (so that we don't leak memory).

Change-Id: Id9dd331800d87b017a500a6f579df446057f555b
Reviewed-on: https://code.wireshark.org/review/22941
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 12 insertions, 9 deletions

diff --git a/epan/dissectors/packet-ssl-utils.c b/epan/dissectors/packet-ssl-utils.c
index 1abf74e2b4..cd94d70fc1 100644
--- a/epan/dissectors/packet-ssl-utils.c
+++ b/epan/dissectors/packet-ssl-utils.c
@@ -4641,23 +4641,26 @@ ssl_parse_key_list(const ssldecrypt_assoc_t *uats, GHashTable *key_hash, const c
 
     if ((gint)strlen(uats->password) == 0) {
         priv_key = rsa_load_pem_key(fp, &err);
-        if (err) {
-            ssl_debug_printf("%s\n", err);
-            g_free(err);
-        }
     } else {
         priv_key = rsa_load_pkcs12(fp, uats->password, &err);
-        if (err) {
-            report_failure("%s\n", err);
-            g_free(err);
-        }
     }
     fclose(fp);
 
     if (!priv_key) {
-        report_failure("Can't load private key from %s\n", uats->keyfile);
+        if (err) {
+            report_failure("Can't load private key from %s: %s",
+                           uats->keyfile, err);
+            g_free(err);
+        } else
+            report_failure("Can't load private key from %s: unknown error",
+                           uats->keyfile);
         return;
     }
+    if (err) {
+        report_failure("Load of private key from %s \"succeeded\" with error %s",
+                       uats->keyfile, err);
+        g_free(err);
+    }
 
     key_id = (guchar *) g_malloc0(key_id_len);
     ret = gnutls_x509_privkey_get_key_id(priv_key, 0, key_id, &key_id_len);