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 <asm/unaligned.h>
  26
  27 #include "dlm_internal.h"
  28 #include "lowcomms.h"
  29 #include "config.h"
  30 #include "lock.h"
  31 #include "midcomms.h"
  32
  33 /*
  34  * Called from the low-level comms layer to process a buffer of
  35  * commands.
  36  */
  37
  38 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
  39 {
  40         const unsigned char *ptr = buf;
  41         const struct dlm_header *hd;
  42         uint16_t msglen;
  43         int ret = 0;
  44
  45         while (len >= sizeof(struct dlm_header)) {
  46                 hd = (struct dlm_header *)ptr;
  47
  48                 /* no message should be more than this otherwise we
  49                  * cannot deliver this message to upper layers
  50                  */
  51                 msglen = get_unaligned_le16(&hd->h_length);
  52                 if (msglen > DEFAULT_BUFFER_SIZE) {
  53                         log_print("received invalid length header: %u, will abort message parsing",
  54                                   msglen);
  55                         return -EBADMSG;
  56                 }
  57
  58                 /* caller will take care that leftover
  59                  * will be parsed next call with more data
  60                  */
  61                 if (msglen > len)
  62                         break;
  63
  64                 switch (hd->h_cmd) {
  65                 case DLM_MSG:
  66                         if (msglen < sizeof(struct dlm_message)) {
  67                                 log_print("dlm msg too small: %u, will skip this message",
  68                                           msglen);
  69                                 goto skip;
  70                         }
  71
  72                         break;
  73                 case DLM_RCOM:
  74                         if (msglen < sizeof(struct dlm_rcom)) {
  75                                 log_print("dlm rcom msg too small: %u, will skip this message",
  76                                           msglen);
  77                                 goto skip;
  78                         }
  79
  80                         break;
  81                 default:
  82                         log_print("unsupported h_cmd received: %u, will skip this message",
  83                                   hd->h_cmd);
  84                         goto skip;
  85                 }
  86
  87                 /* for aligned memory access, we just copy current message
  88                  * to begin of the buffer which contains already parsed buffer
  89                  * data and should provide align access for upper layers
  90                  * because the start address of the buffer has a aligned
  91                  * address. This memmove can be removed when the upperlayer
  92                  * is capable of unaligned memory access.
  93                  */
  94                 memmove(buf, ptr, msglen);
  95                 dlm_receive_buffer((union dlm_packet *)buf, nodeid);
  96
  97 skip:
  98                 ret += msglen;
  99                 len -= msglen;
 100                 ptr += msglen;
 101         }
 102
 103         return ret;
 104 }
 105