fs/dlm/midcomms.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /******************************************************************************
   3 *******************************************************************************
   4 **
   5 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
   6 **  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   7 **
   8 **
   9 *******************************************************************************
  10 ******************************************************************************/
  11
  12 /*
  13  * midcomms.c
  14  *
  15  * This is the appallingly named "mid-level" comms layer.
  16  *
  17  * Its purpose is to take packets from the "real" comms layer,
  18  * split them up into packets and pass them to the interested
  19  * part of the locking mechanism.
  20  *
  21  * It also takes messages from the locking layer, formats them
  22  * into packets and sends them to the comms layer.
  23  */
  24
  25 #include "dlm_internal.h"
  26 #include "lowcomms.h"
  27 #include "config.h"
  28 #include "lock.h"
  29 #include "midcomms.h"
  30
  31 /*
  32  * Called from the low-level comms layer to process a buffer of
  33  * commands.
  34  */
  35
  36 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
  37 {
  38         const unsigned char *ptr = buf;
  39         const struct dlm_header *hd;
  40         uint16_t msglen;
  41         int ret = 0;
  42
  43         while (len >= sizeof(struct dlm_header)) {
  44                 hd = (struct dlm_header *)ptr;
  45
  46                 /* no message should be more than DEFAULT_BUFFER_SIZE or
  47                  * less than dlm_header size.
  48                  *
  49                  * Some messages does not have a 8 byte length boundary yet
  50                  * which can occur in a unaligned memory access of some dlm
  51                  * messages. However this problem need to be fixed at the
  52                  * sending side, for now it seems nobody run into architecture
  53                  * related issues yet but it slows down some processing.
  54                  * Fixing this issue should be scheduled in future by doing
  55                  * the next major version bump.
  56                  */
  57                 msglen = le16_to_cpu(hd->h_length);
  58                 if (msglen > DEFAULT_BUFFER_SIZE ||
  59                     msglen < sizeof(struct dlm_header)) {
  60                         log_print("received invalid length header: %u from node %d, will abort message parsing",
  61                                   msglen, nodeid);
  62                         return -EBADMSG;
  63                 }
  64
  65                 /* caller will take care that leftover
  66                  * will be parsed next call with more data
  67                  */
  68                 if (msglen > len)
  69                         break;
  70
  71                 switch (hd->h_cmd) {
  72                 case DLM_MSG:
  73                         if (msglen < sizeof(struct dlm_message)) {
  74                                 log_print("dlm msg too small: %u, will skip this message",
  75                                           msglen);
  76                                 goto skip;
  77                         }
  78
  79                         break;
  80                 case DLM_RCOM:
  81                         if (msglen < sizeof(struct dlm_rcom)) {
  82                                 log_print("dlm rcom msg too small: %u, will skip this message",
  83                                           msglen);
  84                                 goto skip;
  85                         }
  86
  87                         break;
  88                 default:
  89                         log_print("unsupported h_cmd received: %u, will skip this message",
  90                                   hd->h_cmd);
  91                         goto skip;
  92                 }
  93
  94                 dlm_receive_buffer((union dlm_packet *)ptr, nodeid);
  95
  96 skip:
  97                 ret += msglen;
  98                 len -= msglen;
  99                 ptr += msglen;
 100         }
 101
 102         return ret;
 103 }
 104