Added checksum calculations for events larger than 2^24 bytes

The checksums are now properly calculated for large events that span multiple
SQL packets.

server/modules/include/blr.h

@@ -424,6 +424,7 @@ typedef struct router_instance {
 	int			trx_safe;	/*< Detect and handle partial transactions */
 	int			pending_transaction; /*< Pending transaction */
 	enum blr_event_state master_event_state; /*< Packet read state */
+	uint32_t	stored_checksum; /*< The current value of the checksum */
 	REP_HEADER	stored_header; /*< Relication header of the event the master is sending */
 	uint64_t		last_safe_pos; /* last committed transaction */
 	char			binlog_name[BINLOG_FNAMELEN+1];

server/modules/include/mysql_client_server_protocol.h

@@ -70,6 +70,7 @@
 #define GW_MYSQL_READ 0
 #define GW_MYSQL_WRITE 1
 #define MYSQL_HEADER_LEN 4L
+#define MYSQL_CHECKSUM_LEN 4L
 
 #define GW_MYSQL_PROTOCOL_VERSION 10 // version is 10
 #define GW_MYSQL_HANDSHAKE_FILLER 0x00

server/modules/routing/binlog/blr_master.c

@@ -1002,38 +1002,6 @@ uint32_t 		partialpos = 0;
 #ifdef SHOW_EVENTS
 					printf("blr: len %lu, event type 0x%02x, flags 0x%04x, event size %d, event timestamp %lu\n", (unsigned long)len-4, hdr.event_type, hdr.flags, hdr.event_size, (unsigned long)hdr.timestamp);
 #endif
-					/*
-					 * First check that the checksum we calculate matches the
-					 * checksum in the packet we received.
-					 */
-					if (router->master_chksum &&
-						router->master_event_state == BLR_EVENT_DONE)
-					{
-						uint32_t	chksum, pktsum;
-
-						chksum = crc32(0L, NULL, 0);
-						chksum = crc32(chksum, ptr + 5, hdr.event_size  - 4);
-						pktsum = EXTRACT32(ptr + hdr.event_size + 1);
-						if (pktsum != chksum)
-						{
-							router->stats.n_badcrc++;
-							if (msg)
-							{
-								free(msg);
-								msg = NULL;
-							}
-							MXS_ERROR("%s: Checksum error in event "
-                                 				 "from master, "
-                             					     "binlog %s @ %lu. "
-                           					       "Closing master connection.",
-                                  					router->service->name,
-                                 					 router->binlog_name,
-                                  					router->current_pos);
-							blr_master_close(router);
-							blr_master_delayed_connect(router);
-							return;
-						}
-					}
 				}
             }
 
@@ -1050,27 +1018,40 @@ uint32_t 		partialpos = 0;
                 }
                 else
                 {
-					/* pending 16 mb */
                     /* current partial event is being written to disk file */
-					uint32_t offset = 4;
+                    uint32_t offset = MYSQL_HEADER_LEN;
+                    uint32_t extra_bytes = MYSQL_HEADER_LEN;
 
                     /** Don't write the OK byte into the binlog */
                     if (router->master_event_state == BLR_EVENT_STARTED)
                     {
-						offset++;
+                        offset = MYSQL_HEADER_LEN + 1;
                         router->master_event_state = BLR_EVENT_ONGOING;
+
+                        /** Initialize the checksum and calculate it for
+                         * the first packet */
+                        if (router->master_chksum)
+                        {
+                            router->stored_checksum = crc32(0L, NULL, 0);
+                            extra_bytes = MYSQL_HEADER_LEN + 1;
+                        }
+                    }
+
+                    if (router->master_chksum)
+                    {
+                        router->stored_checksum = crc32(router->stored_checksum,
+                                                        ptr + offset,
+                                                        len - extra_bytes);
                     }
 
                     if (blr_write_data_into_binlog(router, len - offset, ptr + offset) == 0)
                     {
-						/*
+                        /** Failed to write to the binlog file, destroy the buffer
-						 * Failed to write to the
+                         * chain and close the connection with the master */
-						 * binlog file, destroy the
+                        while (pkt)
-						 * buffer chain and close the
+                        {
-						 * connection with the master
+                            pkt = GWBUF_CONSUME_ALL(pkt);
-						 */
+                        }
-						while ((pkt = gwbuf_consume(pkt,
-													GWBUF_LENGTH(pkt))) != NULL);
                         blr_master_close(router);
                         blr_master_delayed_connect(router);
                         return;
@@ -1081,6 +1062,43 @@ uint32_t 		partialpos = 0;
                 }
             }
 
+            /*
+             * First check that the checksum we calculate matches the
+             * checksum in the packet we received.
+             */
+            if (router->master_chksum)
+            {
+                uint32_t pktsum, offset = MYSQL_HEADER_LEN;
+                uint32_t size = len - MYSQL_HEADER_LEN - MYSQL_CHECKSUM_LEN;
+
+                if (router->master_event_state == BLR_EVENT_DONE)
+                {
+                    /** Initialize the checksum and set the pointer offset to
+                     * the first byte after the header and OK byte */
+                    router->stored_checksum = crc32(0L, NULL, 0);
+                    offset = MYSQL_HEADER_LEN + 1;
+                    size = len - MYSQL_HEADER_LEN - MYSQL_CHECKSUM_LEN - 1;
+                }
+
+                router->stored_checksum = crc32(router->stored_checksum,
+                                                ptr + offset, size);
+
+                pktsum = EXTRACT32(ptr + len - MYSQL_CHECKSUM_LEN);
+                if (pktsum != router->stored_checksum)
+                {
+                    router->stats.n_badcrc++;
+                    free(msg);
+                    msg = NULL;
+                    MXS_ERROR("%s: Checksum error in event from master, "
+                              "binlog %s @ %lu. Closing master connection.",
+                              router->service->name, router->binlog_name,
+                              router->current_pos);
+                    blr_master_close(router);
+                    blr_master_delayed_connect(router);
+                    return;
+                }
+            }
+
 			if (hdr.ok == 0)
 			{
 				router->lastEventReceived = hdr.event_type;