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         struct fd_event *fde;
  50         int fd;
  51         size_t alignment;
  52         void *private_data;
  53         ctdb_queue_cb_fn_t callback;
  54 };
  55
  56
  57
  58 /*
  59   called when an incoming connection is readable
  60 */
  61 static void queue_io_read(struct ctdb_queue *queue)
  62 {
  63         int num_ready = 0;
  64         ssize_t nread;
  65         uint8_t *data, *data_base;
  66
  67         if (ioctl(queue->fd, FIONREAD, &num_ready) != 0) {
  68                 return;
  69         }
  70         if (num_ready == 0) {
  71                 /* the descriptor has been closed */
  72                 goto failed;
  73         }
  74
  75
  76         queue->partial.data = talloc_realloc_size(queue, queue->partial.data,
  77                                                   num_ready + queue->partial.length);
  78
  79         if (queue->partial.data == NULL) {
  80                 DEBUG(DEBUG_ERR,("read error alloc failed for %u\n",
  81                          num_ready + queue->partial.length));
  82                 goto failed;
  83         }
  84
  85         nread = read(queue->fd, queue->partial.data + queue->partial.length, num_ready);
  86         if (nread <= 0) {
  87                 DEBUG(DEBUG_ERR,("read error nread=%d\n", (int)nread));
  88                 goto failed;
  89         }
  90
  91
  92         data = queue->partial.data;
  93         nread += queue->partial.length;
  94
  95         queue->partial.data = NULL;
  96         queue->partial.length = 0;
  97
  98         if (nread >= 4 && *(uint32_t *)data == nread) {
  99                 /* it is the responsibility of the incoming packet
 100                  function to free 'data' */
 101                 queue->callback(data, nread, queue->private_data);
 102                 return;
 103         }
 104
 105         data_base = data;
 106
 107         while (nread >= 4 && *(uint32_t *)data <= nread) {
 108                 /* we have at least one packet */
 109                 uint8_t *d2;
 110                 uint32_t len;
 111                 len = *(uint32_t *)data;
 112                 if (len == 0) {
 113                         /* bad packet! treat as EOF */
 114                         DEBUG(DEBUG_CRIT,("Invalid packet of length 0\n"));
 115                         goto failed;
 116                 }
 117                 d2 = talloc_memdup(queue, data, len);
 118                 if (d2 == NULL) {
 119                         DEBUG(DEBUG_ERR,("read error memdup failed for %u\n", len));
 120                         /* sigh */
 121                         goto failed;
 122                 }
 123                 queue->callback(d2, len, queue->private_data);
 124                 data += len;
 125                 nread -= len;
 126         }
 127
 128         if (nread > 0) {
 129                 /* we have only part of a packet */
 130                 if (data_base == data) {
 131                         queue->partial.data = data;
 132                         queue->partial.length = nread;
 133                 } else {
 134                         queue->partial.data = talloc_memdup(queue, data, nread);
 135                         if (queue->partial.data == NULL) {
 136                                 DEBUG(DEBUG_ERR,("read error memdup partial failed for %u\n",
 137                                          (unsigned)nread));
 138                                 goto failed;
 139                         }
 140                         queue->partial.length = nread;
 141                         talloc_free(data_base);
 142                 }
 143                 return;
 144         }
 145
 146         talloc_free(data_base);
 147         return;
 148
 149 failed:
 150         queue->callback(NULL, 0, queue->private_data);
 151 }
 152
 153
 154 /* used when an event triggers a dead queue */
 155 static void queue_dead(struct event_context *ev, struct timed_event *te,
 156                        struct timeval t, void *private_data)
 157 {
 158         struct ctdb_queue *queue = talloc_get_type(private_data, struct ctdb_queue);
 159         queue->callback(NULL, 0, queue->private_data);
 160 }
 161
 162
 163 /*
 164   called when an incoming connection is writeable
 165 */
 166 static void queue_io_write(struct ctdb_queue *queue)
 167 {
 168         while (queue->out_queue) {
 169                 struct ctdb_queue_pkt *pkt = queue->out_queue;
 170                 ssize_t n;
 171                 if (queue->ctdb->flags & CTDB_FLAG_TORTURE) {
 172                         n = write(queue->fd, pkt->data, 1);
 173                 } else {
 174                         n = write(queue->fd, pkt->data, pkt->length);
 175                 }
 176
 177                 if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
 178                         if (pkt->length != pkt->full_length) {
 179                                 /* partial packet sent - we have to drop it */
 180                                 DLIST_REMOVE(queue->out_queue, pkt);
 181                                 talloc_free(pkt);
 182                         }
 183                         talloc_free(queue->fde);
 184                         queue->fde = NULL;
 185                         queue->fd = -1;
 186                         event_add_timed(queue->ctdb->ev, queue, timeval_zero(),
 187                                         queue_dead, queue);
 188                         return;
 189                 }
 190                 if (n <= 0) return;
 191
 192                 if (n != pkt->length) {
 193                         pkt->length -= n;
 194                         pkt->data += n;
 195                         return;
 196                 }
 197
 198                 DLIST_REMOVE(queue->out_queue, pkt);
 199                 talloc_free(pkt);
 200         }
 201
 202         EVENT_FD_NOT_WRITEABLE(queue->fde);
 203 }
 204
 205 /*
 206   called when an incoming connection is readable or writeable
 207 */
 208 static void queue_io_handler(struct event_context *ev, struct fd_event *fde,
 209                              uint16_t flags, void *private_data)
 210 {
 211         struct ctdb_queue *queue = talloc_get_type(private_data, struct ctdb_queue);
 212
 213         if (flags & EVENT_FD_READ) {
 214                 queue_io_read(queue);
 215         } else {
 216                 queue_io_write(queue);
 217         }
 218 }
 219
 220
 221 /*
 222   queue a packet for sending
 223 */
 224 int ctdb_queue_send(struct ctdb_queue *queue, uint8_t *data, uint32_t length)
 225 {
 226         struct ctdb_queue_pkt *pkt;
 227         uint32_t length2, full_length;
 228
 229         if (queue->alignment) {
 230                 /* enforce the length and alignment rules from the tcp packet allocator */
 231                 length2 = (length+(queue->alignment-1)) & ~(queue->alignment-1);
 232                 *(uint32_t *)data = length2;
 233         } else {
 234                 length2 = length;
 235         }
 236
 237         if (length2 != length) {
 238                 memset(data+length, 0, length2-length);
 239         }
 240
 241         full_length = length2;
 242
 243         /* if the queue is empty then try an immediate write, avoiding
 244            queue overhead. This relies on non-blocking sockets */
 245         if (queue->out_queue == NULL && queue->fd != -1 &&
 246             !(queue->ctdb->flags & CTDB_FLAG_TORTURE)) {
 247                 ssize_t n = write(queue->fd, data, length2);
 248                 if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
 249                         talloc_free(queue->fde);
 250                         queue->fde = NULL;
 251                         queue->fd = -1;
 252                         event_add_timed(queue->ctdb->ev, queue, timeval_zero(),
 253                                         queue_dead, queue);
 254                         /* yes, we report success, as the dead node is
 255                            handled via a separate event */
 256                         return 0;
 257                 }
 258                 if (n > 0) {
 259                         data += n;
 260                         length2 -= n;
 261                 }
 262                 if (length2 == 0) return 0;
 263         }
 264
 265         pkt = talloc(queue, struct ctdb_queue_pkt);
 266         CTDB_NO_MEMORY(queue->ctdb, pkt);
 267
 268         pkt->data = talloc_memdup(pkt, data, length2);
 269         CTDB_NO_MEMORY(queue->ctdb, pkt->data);
 270
 271         pkt->length = length2;
 272         pkt->full_length = full_length;
 273
 274         if (queue->out_queue == NULL && queue->fd != -1) {
 275                 EVENT_FD_WRITEABLE(queue->fde);
 276         }
 277
 278         DLIST_ADD_END(queue->out_queue, pkt, struct ctdb_queue_pkt *);
 279
 280         if (queue->ctdb->tunable.verbose_memory_names != 0) {
 281                 struct ctdb_req_header *hdr = (struct ctdb_req_header *)pkt->data;
 282                 switch (hdr->operation) {
 283                 case CTDB_REQ_CONTROL: {
 284                         struct ctdb_req_control *c = (struct ctdb_req_control *)hdr;
 285                         talloc_set_name(pkt, "ctdb_queue_pkt: control opcode=%u srvid=%llu datalen=%u",
 286                                         (unsigned)c->opcode, (unsigned long long)c->srvid, (unsigned)c->datalen);
 287                         break;
 288                 }
 289                 case CTDB_REQ_MESSAGE: {
 290                         struct ctdb_req_message *m = (struct ctdb_req_message *)hdr;
 291                         talloc_set_name(pkt, "ctdb_queue_pkt: message srvid=%llu datalen=%u",
 292                                         (unsigned long long)m->srvid, (unsigned)m->datalen);
 293                         break;
 294                 }
 295                 default:
 296                         talloc_set_name(pkt, "ctdb_queue_pkt: operation=%u length=%u src=%u dest=%u",
 297                                         (unsigned)hdr->operation, (unsigned)hdr->length,
 298                                         (unsigned)hdr->srcnode, (unsigned)hdr->destnode);
 299                         break;
 300                 }
 301         }
 302
 303         return 0;
 304 }
 305
 306
 307 /*
 308   setup the fd used by the queue
 309  */
 310 int ctdb_queue_set_fd(struct ctdb_queue *queue, int fd)
 311 {
 312         queue->fd = fd;
 313         talloc_free(queue->fde);
 314         queue->fde = NULL;
 315
 316         if (fd != -1) {
 317                 queue->fde = event_add_fd(queue->ctdb->ev, queue, fd, EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
 318                                           queue_io_handler, queue);
 319                 if (queue->fde == NULL) {
 320                         return -1;
 321                 }
 322
 323                 if (queue->out_queue) {
 324                         EVENT_FD_WRITEABLE(queue->fde);
 325                 }
 326         }
 327
 328         return 0;
 329 }
 330
 331
 332
 333 /*
 334   setup a packet queue on a socket
 335  */
 336 struct ctdb_queue *ctdb_queue_setup(struct ctdb_context *ctdb,
 337                                     TALLOC_CTX *mem_ctx, int fd, int alignment,
 338
 339                                     ctdb_queue_cb_fn_t callback,
 340                                     void *private_data)
 341 {
 342         struct ctdb_queue *queue;
 343
 344         queue = talloc_zero(mem_ctx, struct ctdb_queue);
 345         CTDB_NO_MEMORY_NULL(ctdb, queue);
 346
 347         queue->ctdb = ctdb;
 348         queue->fd = fd;
 349         queue->alignment = alignment;
 350         queue->private_data = private_data;
 351         queue->callback = callback;
 352         if (fd != -1) {
 353                 if (ctdb_queue_set_fd(queue, fd) != 0) {
 354                         talloc_free(queue);
 355                         return NULL;
 356                 }
 357         }
 358
 359         return queue;
 360 }