Moved common sharding functions to a separate file.

server/modules/routing/schemarouter/sharding_common.c

@@ -0,0 +1,161 @@
+/*
+ * This file is distributed as part of the MariaDB Corporation MaxScale.  It is free
+ * software: you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation,
+ * version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Copyright MariaDB Corporation Ab 2013-2015
+ */
+
+#include <sharding_common.h>
+
+/** Defined in log_manager.cc */
+extern int            lm_enabled_logfiles_bitmask;
+extern size_t         log_ses_count[];
+extern __thread log_info_t tls_log_info;
+
+/**
+ * Extract the database name from a COM_INIT_DB or literal USE ... query.
+ * @param buf Buffer with the database change query
+ * @param str Pointer where the database name is copied
+ * @return True for success, false for failure
+ */
+bool extract_database(GWBUF* buf, char* str)
+{
+     uint8_t* packet;
+    char *saved,*tok,*query = NULL;
+    bool succp = true;
+    unsigned int plen;
+
+    packet = GWBUF_DATA(buf);
+    plen = gw_mysql_get_byte3(packet) - 1;
+
+    /** Copy database name from MySQL packet to session */
+    if(query_classifier_get_operation(buf) == QUERY_OP_CHANGE_DB)
+    {
+	query = modutil_get_SQL(buf);
+	tok = strtok_r(query," ;",&saved);
+	if(tok == NULL || strcasecmp(tok,"use") != 0)
+	{
+	    skygw_log_write(LOGFILE_ERROR,"Schemarouter: Malformed chage database packet.");
+	    succp = false;
+	    goto retblock;
+	}
+
+	tok = strtok_r(NULL," ;",&saved);
+	if(tok == NULL)
+	{
+	    skygw_log_write(LOGFILE_ERROR,"Schemarouter: Malformed chage database packet.");
+	    succp = false;
+	    goto retblock;
+	}
+
+	strncpy(str,tok,MYSQL_DATABASE_MAXLEN);
+    }
+    else
+    {
+	memcpy(str,packet + 5,plen);
+	memset(str + plen,0,1);
+    }
+    retblock:
+    free(query);
+    return succp;
+}
+
+/**
+ * Create a fake error message from a DCB.
+ * @param fail_str Custom error message
+ * @param dcb DCB to use as the origin of the error
+ */
+void create_error_reply(char* fail_str,DCB* dcb)
+{
+    skygw_log_write_flush(
+	    LOGFILE_TRACE,
+	    "change_current_db: failed to change database: %s", fail_str);
+    GWBUF* errbuf = modutil_create_mysql_err_msg(1, 0, 1049, "42000", fail_str);
+
+    if (errbuf == NULL)
+    {
+	LOGIF(LE, (skygw_log_write_flush(
+		LOGFILE_ERROR,
+		"Error : Creating buffer for error message failed.")));
+	return;
+    }
+    /** Set flags that help router to identify session commands reply */
+    gwbuf_set_type(errbuf, GWBUF_TYPE_MYSQL);
+    gwbuf_set_type(errbuf, GWBUF_TYPE_SESCMD_RESPONSE);
+    gwbuf_set_type(errbuf, GWBUF_TYPE_RESPONSE_END);
+
+    poll_add_epollin_event_to_dcb(dcb,
+				  errbuf);
+}
+
+/**
+ * Read new database name from MYSQL_COM_INIT_DB packet or a literal USE ... COM_QUERY packet, check that it exists
+ * in the hashtable and copy its name to MYSQL_session.
+ *
+ * @param mysql_session The MySQL session structure
+ * @param dbhash Hashtable containing valid databases
+ * @param buf	Buffer containing the database change query
+ *
+ * @return true if new database is set, false if non-existent database was tried
+ * to be set
+ */
+bool change_current_db(MYSQL_session* mysql_session,
+			      HASHTABLE* dbhash,
+			      GWBUF* buf)
+{
+    char* target;
+    bool succp;
+    char db[MYSQL_DATABASE_MAXLEN+1];
+    if(GWBUF_LENGTH(buf) <= MYSQL_DATABASE_MAXLEN - 5)
+    {
+	/** Copy database name from MySQL packet to session */
+	if(!extract_database(buf,db))
+	{
+	    succp = false;
+	    goto retblock;
+	}
+	skygw_log_write(LOGFILE_TRACE,"change_current_db: INIT_DB with database '%s'",
+		 db);
+	/**
+	 * Update the session's active database only if it's in the hashtable.
+	 * If it isn't found, send a custom error packet to the client.
+	 */
+
+	if((target = (char*)hashtable_fetch(dbhash,(char*)db)) == NULL)
+	{
+	    succp = false;
+	    goto retblock;
+	}
+	else
+	{
+	    strncpy(mysql_session->db,db,MYSQL_DATABASE_MAXLEN);
+	    skygw_log_write(LOGFILE_TRACE,"change_current_db: database is on server: '%s'.",target);
+	    succp = true;
+	    goto retblock;
+	}
+    }
+    else
+    {
+	/** Create error message */
+	skygw_log_write_flush(LOGFILE_ERROR,
+			 "change_current_db: failed to change database: Query buffer too large");
+	skygw_log_write_flush(LOGFILE_TRACE,
+			 "change_current_db: failed to change database: Query buffer too large [%d bytes]",GWBUF_LENGTH(buf));
+	succp = false;
+	goto retblock;
+    }
+    
+    retblock:
+    return succp;
+}