Improve OpenSSL integration

Ensure the error stack is cleared after errors are processed.

Also handle NULL returns safely.

Makes the debug mode spew more data, though almost none of
the contexts is in reaction to network peer data.

common.c

@@ -50,6 +50,30 @@ init_openssl (void)
 
 // --- To be moved to liberty --------------------------------------------------
 
+// FIXME: in xssl_get_error() we rely on error reasons never being NULL (i.e.,
+//   all loaded), which isn't very robust.
+// TODO: check all places where this is used and see if we couldn't gain better
+//   information by piecing together some other subset of data from the error
+//   stack.  Most often, this is used in an error_set() context, which would
+//   allow us to allocate memory instead of returning static strings.
+static const char *
+xerr_describe_error (void)
+{
+	unsigned long err = ERR_get_error ();
+	if (!err)
+		return "undefined error";
+
+	const char *reason = ERR_reason_error_string (err);
+	do
+		// Not thread-safe, not a concern right now--need a buffer
+		print_debug ("%s", ERR_error_string (err, NULL));
+	while ((err = ERR_get_error ()));
+
+	if (!reason)
+		return "cannot retrieve error description";
+	return reason;
+}
+
 static ssize_t
 strv_find (const struct strv *v, const char *s)
 {

degesch.c

@@ -5320,13 +5320,13 @@ transport_tls_init_ca_set (SSL_CTX *ssl_ctx, const char *file, const char *path,
 
 		return error_set (e, "%s: %s",
 			"Failed to set locations for the CA certificate bundle",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	}
 
 	if (!SSL_CTX_set_default_verify_paths (ssl_ctx))
 		return error_set (e, "%s: %s",
 			"Couldn't load the default CA certificate bundle",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	return true;
 }
 
@@ -5416,7 +5416,7 @@ transport_tls_init_cert (struct server *s, SSL *ssl, struct error **e)
 	else if (!SSL_use_certificate_file (ssl, path, SSL_FILETYPE_PEM)
 		|| !SSL_use_PrivateKey_file (ssl, path, SSL_FILETYPE_PEM))
 		error_set (e, "%s: %s", "Setting the TLS client certificate failed",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	else
 		result = true;
 	free (path);
@@ -5474,7 +5474,7 @@ error_ssl_2:
 error_ssl_1:
 	if (!error)
 		error_set (&error, "%s: %s", "Could not initialize TLS",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 
 	error_propagate (e, error);
 	return false;

kike.c

@@ -3261,7 +3261,7 @@ error_ssl_3:
 	SSL_free (c->ssl);
 	c->ssl = NULL;
 error_ssl_2:
-	error_info = ERR_reason_error_string (ERR_get_error ());
+	error_info = xerr_describe_error ();
 error_ssl_1:
 	print_debug ("could not initialize TLS for %s: %s", c->address, error_info);
 	return false;
@@ -3540,7 +3540,7 @@ irc_initialize_ssl_ctx (struct server_context *ctx,
 	if (!ctx->ssl_ctx)
 	{
 		error_set (e, "%s: %s", "could not initialize TLS",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 		return false;
 	}
 	SSL_CTX_set_verify (ctx->ssl_ctx,
@@ -3570,11 +3570,11 @@ irc_initialize_ssl_ctx (struct server_context *ctx,
 		error_set (e, "failed to select any cipher from the cipher list");
 	else if (!SSL_CTX_use_certificate_chain_file (ctx->ssl_ctx, cert_path))
 		error_set (e, "%s: %s", "setting the TLS certificate failed",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	else if (!SSL_CTX_use_PrivateKey_file
 		(ctx->ssl_ctx, key_path, SSL_FILETYPE_PEM))
 		error_set (e, "%s: %s", "setting the TLS private key failed",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	else
 		// TODO: SSL_CTX_check_private_key()?  It has probably already been
 		//   checked by SSL_CTX_use_PrivateKey_file() above.

zyklonb.c

@@ -280,7 +280,7 @@ irc_send (struct bot_context *ctx, const char *format, ...)
 		if (SSL_write (ctx->ssl, str.str, str.len) != (int) str.len)
 		{
 			print_debug ("%s: %s: %s", __func__, "SSL_write",
-				ERR_error_string (ERR_get_error (), NULL));
+				xerr_describe_error ());
 			result = false;
 		}
 	}
@@ -320,13 +320,13 @@ irc_initialize_ca_set (SSL_CTX *ssl_ctx, const char *file, const char *path,
 
 		return error_set (e, "%s: %s",
 			"failed to set locations for the CA certificate bundle",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	}
 
 	if (!SSL_CTX_set_default_verify_paths (ssl_ctx))
 		return error_set (e, "%s: %s",
 			"couldn't load the default CA certificate bundle",
-			ERR_reason_error_string (ERR_get_error ()));
+			xerr_describe_error ());
 	return true;
 }
 
@@ -407,7 +407,7 @@ irc_initialize_tls (struct bot_context *ctx, struct error **e)
 		else if (!SSL_use_certificate_file (ctx->ssl, path, SSL_FILETYPE_PEM)
 			|| !SSL_use_PrivateKey_file (ctx->ssl, path, SSL_FILETYPE_PEM))
 			print_error ("%s: %s", "setting the TLS client certificate failed",
-				ERR_error_string (ERR_get_error (), NULL));
+				xerr_describe_error ());
 		free (path);
 	}
 
@@ -434,10 +434,8 @@ error_ssl_2:
 	SSL_CTX_free (ctx->ssl_ctx);
 	ctx->ssl_ctx = NULL;
 error_ssl_1:
-	// XXX: these error strings are really nasty; also there could be
-	//   multiple errors on the OpenSSL stack.
 	if (!error_info)
-		error_info = ERR_error_string (ERR_get_error (), NULL);
+		error_info = xerr_describe_error ();
 	return error_set (e, "%s: %s", "could not initialize TLS", error_info);
 }