ctdb/common/ctdb_io.c

   1 /*
   2    ctdb database library
   3    Utility functions to read/write blobs of data from a file descriptor
   4    and handle the case where we might need multiple read/writes to get all the
   5    data.
   6
   7    Copyright (C) Andrew Tridgell  2006
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "lib/tdb/include/tdb.h"
  25 #include "lib/events/events.h"
  26 #include "lib/util/dlinklist.h"
  27 #include "system/network.h"
  28 #include "system/filesys.h"
  29 #include "../include/ctdb_private.h"
  30 #include "../include/ctdb.h"
  31
  32 /* structures for packet queueing - see common/ctdb_io.c */
  33 struct ctdb_partial {
  34         uint8_t *data;
  35         uint32_t length;
  36 };
  37
  38 struct ctdb_queue_pkt {
  39         struct ctdb_queue_pkt *next, *prev;
  40         uint8_t *data;
  41         uint32_t length;
  42         uint32_t full_length;
  43 };
  44
  45 struct ctdb_queue {
  46         struct ctdb_context *ctdb;
  47         struct ctdb_partial partial; /* partial input packet */
  48         struct ctdb_queue_pkt *out_queue;
  49         uint32_t out_queue_length;
  50         struct fd_event *fde;
  51         int fd;
  52         size_t alignment;
  53         void *private_data;
  54         ctdb_queue_cb_fn_t callback;
  55 };
  56
  57
  58
  59 int ctdb_queue_length(struct ctdb_queue *queue)
  60 {
  61         return queue->out_queue_length;
  62 }
  63
  64 /*
  65   called when an incoming connection is readable
  66 */
  67 static void queue_io_read(struct ctdb_queue *queue)
  68 {
  69         int num_ready = 0;
  70         ssize_t nread;
  71         uint8_t *data, *data_base;
  72
  73         if (ioctl(queue->fd, FIONREAD, &num_ready) != 0) {
  74                 return;
  75         }
  76         if (num_ready == 0) {
  77                 /* the descriptor has been closed */
  78                 goto failed;
  79         }
  80
  81
  82         queue->partial.data = talloc_realloc_size(queue, queue->partial.data,
  83                                                   num_ready + queue->partial.length);
  84
  85         if (queue->partial.data == NULL) {
  86                 DEBUG(DEBUG_ERR,("read error alloc failed for %u\n",
  87                          num_ready + queue->partial.length));
  88                 goto failed;
  89         }
  90
  91         nread = read(queue->fd, queue->partial.data + queue->partial.length, num_ready);
  92         if (nread <= 0) {
  93                 DEBUG(DEBUG_ERR,("read error nread=%d\n", (int)nread));
  94                 goto failed;
  95         }
  96
  97
  98         data = queue->partial.data;
  99         nread += queue->partial.length;
 100
 101         queue->partial.data = NULL;
 102         queue->partial.length = 0;
 103
 104         if (nread >= 4 && *(uint32_t *)data == nread) {
 105                 /* it is the responsibility of the incoming packet
 106                  function to free 'data' */
 107                 queue->callback(data, nread, queue->private_data);
 108                 return;
 109         }
 110
 111         data_base = data;
 112
 113         while (nread >= 4 && *(uint32_t *)data <= nread) {
 114                 /* we have at least one packet */
 115                 uint8_t *d2;
 116                 uint32_t len;
 117                 len = *(uint32_t *)data;
 118                 if (len == 0) {
 119                         /* bad packet! treat as EOF */
 120                         DEBUG(DEBUG_CRIT,("Invalid packet of length 0\n"));
 121                         goto failed;
 122                 }
 123                 d2 = talloc_memdup(queue, data, len);
 124                 if (d2 == NULL) {
 125                         DEBUG(DEBUG_ERR,("read error memdup failed for %u\n", len));
 126                         /* sigh */
 127                         goto failed;
 128                 }
 129                 queue->callback(d2, len, queue->private_data);
 130                 data += len;
 131                 nread -= len;
 132         }
 133
 134         if (nread > 0) {
 135                 /* we have only part of a packet */
 136                 if (data_base == data) {
 137                         queue->partial.data = data;
 138                         queue->partial.length = nread;
 139                 } else {
 140                         queue->partial.data = talloc_memdup(queue, data, nread);
 141                         if (queue->partial.data == NULL) {
 142                                 DEBUG(DEBUG_ERR,("read error memdup partial failed for %u\n",
 143                                          (unsigned)nread));
 144                                 goto failed;
 145                         }
 146                         queue->partial.length = nread;
 147                         talloc_free(data_base);
 148                 }
 149                 return;
 150         }
 151
 152         talloc_free(data_base);
 153         return;
 154
 155 failed:
 156         queue->callback(NULL, 0, queue->private_data);
 157 }
 158
 159
 160 /* used when an event triggers a dead queue */
 161 static void queue_dead(struct event_context *ev, struct timed_event *te,
 162                        struct timeval t, void *private_data)
 163 {
 164         struct ctdb_queue *queue = talloc_get_type(private_data, struct ctdb_queue);
 165         queue->callback(NULL, 0, queue->private_data);
 166 }
 167
 168
 169 /*
 170   called when an incoming connection is writeable
 171 */
 172 static void queue_io_write(struct ctdb_queue *queue)
 173 {
 174         while (queue->out_queue) {
 175                 struct ctdb_queue_pkt *pkt = queue->out_queue;
 176                 ssize_t n;
 177                 if (queue->ctdb->flags & CTDB_FLAG_TORTURE) {
 178                         n = write(queue->fd, pkt->data, 1);
 179                 } else {
 180                         n = write(queue->fd, pkt->data, pkt->length);
 181                 }
 182
 183                 if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
 184                         if (pkt->length != pkt->full_length) {
 185                                 /* partial packet sent - we have to drop it */
 186                                 DLIST_REMOVE(queue->out_queue, pkt);
 187                                 queue->out_queue_length--;
 188                                 talloc_free(pkt);
 189                         }
 190                         talloc_free(queue->fde);
 191                         queue->fde = NULL;
 192                         queue->fd = -1;
 193                         event_add_timed(queue->ctdb->ev, queue, timeval_zero(),
 194                                         queue_dead, queue);
 195                         return;
 196                 }
 197                 if (n <= 0) return;
 198
 199                 if (n != pkt->length) {
 200                         pkt->length -= n;
 201                         pkt->data += n;
 202                         return;
 203                 }
 204
 205                 DLIST_REMOVE(queue->out_queue, pkt);
 206                 queue->out_queue_length--;
 207                 talloc_free(pkt);
 208         }
 209
 210         EVENT_FD_NOT_WRITEABLE(queue->fde);
 211 }
 212
 213 /*
 214   called when an incoming connection is readable or writeable
 215 */
 216 static void queue_io_handler(struct event_context *ev, struct fd_event *fde,
 217                              uint16_t flags, void *private_data)
 218 {
 219         struct ctdb_queue *queue = talloc_get_type(private_data, struct ctdb_queue);
 220
 221         if (flags & EVENT_FD_READ) {
 222                 queue_io_read(queue);
 223         } else {
 224                 queue_io_write(queue);
 225         }
 226 }
 227
 228
 229 /*
 230   queue a packet for sending
 231 */
 232 int ctdb_queue_send(struct ctdb_queue *queue, uint8_t *data, uint32_t length)
 233 {
 234         struct ctdb_queue_pkt *pkt;
 235         uint32_t length2, full_length;
 236
 237         if (queue->alignment) {
 238                 /* enforce the length and alignment rules from the tcp packet allocator */
 239                 length2 = (length+(queue->alignment-1)) & ~(queue->alignment-1);
 240                 *(uint32_t *)data = length2;
 241         } else {
 242                 length2 = length;
 243         }
 244
 245         if (length2 != length) {
 246                 memset(data+length, 0, length2-length);
 247         }
 248
 249         full_length = length2;
 250
 251         /* if the queue is empty then try an immediate write, avoiding
 252            queue overhead. This relies on non-blocking sockets */
 253         if (queue->out_queue == NULL && queue->fd != -1 &&
 254             !(queue->ctdb->flags & CTDB_FLAG_TORTURE)) {
 255                 ssize_t n = write(queue->fd, data, length2);
 256                 if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
 257                         talloc_free(queue->fde);
 258                         queue->fde = NULL;
 259                         queue->fd = -1;
 260                         event_add_timed(queue->ctdb->ev, queue, timeval_zero(),
 261                                         queue_dead, queue);
 262                         /* yes, we report success, as the dead node is
 263                            handled via a separate event */
 264                         return 0;
 265                 }
 266                 if (n > 0) {
 267                         data += n;
 268                         length2 -= n;
 269                 }
 270                 if (length2 == 0) return 0;
 271         }
 272
 273         pkt = talloc(queue, struct ctdb_queue_pkt);
 274         CTDB_NO_MEMORY(queue->ctdb, pkt);
 275
 276         pkt->data = talloc_memdup(pkt, data, length2);
 277         CTDB_NO_MEMORY(queue->ctdb, pkt->data);
 278
 279         pkt->length = length2;
 280         pkt->full_length = full_length;
 281
 282         if (queue->out_queue == NULL && queue->fd != -1) {
 283                 EVENT_FD_WRITEABLE(queue->fde);
 284         }
 285
 286         DLIST_ADD_END(queue->out_queue, pkt, struct ctdb_queue_pkt *);
 287         queue->out_queue_length++;
 288
 289         if (queue->ctdb->tunable.verbose_memory_names != 0) {
 290                 struct ctdb_req_header *hdr = (struct ctdb_req_header *)pkt->data;
 291                 switch (hdr->operation) {
 292                 case CTDB_REQ_CONTROL: {
 293                         struct ctdb_req_control *c = (struct ctdb_req_control *)hdr;
 294                         talloc_set_name(pkt, "ctdb_queue_pkt: control opcode=%u srvid=%llu datalen=%u",
 295                                         (unsigned)c->opcode, (unsigned long long)c->srvid, (unsigned)c->datalen);
 296                         break;
 297                 }
 298                 case CTDB_REQ_MESSAGE: {
 299                         struct ctdb_req_message *m = (struct ctdb_req_message *)hdr;
 300                         talloc_set_name(pkt, "ctdb_queue_pkt: message srvid=%llu datalen=%u",
 301                                         (unsigned long long)m->srvid, (unsigned)m->datalen);
 302                         break;
 303                 }
 304                 default:
 305                         talloc_set_name(pkt, "ctdb_queue_pkt: operation=%u length=%u src=%u dest=%u",
 306                                         (unsigned)hdr->operation, (unsigned)hdr->length,
 307                                         (unsigned)hdr->srcnode, (unsigned)hdr->destnode);
 308                         break;
 309                 }
 310         }
 311
 312         return 0;
 313 }
 314
 315
 316 /*
 317   setup the fd used by the queue
 318  */
 319 int ctdb_queue_set_fd(struct ctdb_queue *queue, int fd)
 320 {
 321         queue->fd = fd;
 322         talloc_free(queue->fde);
 323         queue->fde = NULL;
 324
 325         if (fd != -1) {
 326                 queue->fde = event_add_fd(queue->ctdb->ev, queue, fd, EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
 327                                           queue_io_handler, queue);
 328                 if (queue->fde == NULL) {
 329                         return -1;
 330                 }
 331
 332                 if (queue->out_queue) {
 333                         EVENT_FD_WRITEABLE(queue->fde);
 334                 }
 335         }
 336
 337         return 0;
 338 }
 339
 340
 341
 342 /*
 343   setup a packet queue on a socket
 344  */
 345 struct ctdb_queue *ctdb_queue_setup(struct ctdb_context *ctdb,
 346                                     TALLOC_CTX *mem_ctx, int fd, int alignment,
 347
 348                                     ctdb_queue_cb_fn_t callback,
 349                                     void *private_data)
 350 {
 351         struct ctdb_queue *queue;
 352
 353         queue = talloc_zero(mem_ctx, struct ctdb_queue);
 354         CTDB_NO_MEMORY_NULL(ctdb, queue);
 355
 356         queue->ctdb = ctdb;
 357         queue->fd = fd;
 358         queue->alignment = alignment;
 359         queue->private_data = private_data;
 360         queue->callback = callback;
 361         if (fd != -1) {
 362                 if (ctdb_queue_set_fd(queue, fd) != 0) {
 363                         talloc_free(queue);
 364                         return NULL;
 365                 }
 366         }
 367
 368         return queue;
 369 }