ctdb/tools/ctdb_killtcp.c

   1 /*
   2    CTDB TCP connection killing utility
   3
   4    Copyright (C) Martin Schwenke <martin@meltin.net> 2016
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include <talloc.h>
  21 #include <tevent.h>
  22
  23 #include "replace.h"
  24 #include "system/network.h"
  25
  26 #include "lib/util/debug.h"
  27 #include "lib/util/tevent_unix.h"
  28
  29 #include "protocol/protocol.h"
  30 #include "protocol/protocol_util.h"
  31
  32 #include "common/db_hash.h"
  33 #include "common/system.h"
  34 #include "common/logging.h"
  35
  36
  37 struct reset_connections_state {
  38         struct tevent_context *ev;
  39         int capture_fd;
  40         struct tevent_fd *fde;
  41         struct db_hash_context *connections;
  42         void *private_data;
  43         unsigned int attempts;
  44         unsigned int max_attempts;
  45         struct timeval retry_interval;
  46         unsigned int batch_count;
  47         unsigned int batch_size;
  48 };
  49
  50
  51 static void reset_connections_capture_tcp_handler(struct tevent_context *ev,
  52                                                   struct tevent_fd *fde,
  53                                                   uint16_t flags,
  54                                                   void *private_data);
  55 static void reset_connections_batch(struct tevent_req *subreq);
  56 static int reset_connections_tickle_connection(
  57                                         uint8_t *keybuf, size_t keylen,
  58                                         uint8_t *databuf, size_t datalen,
  59                                         void *private_data);
  60
  61 static struct tevent_req *reset_connections_send(
  62                               TALLOC_CTX *mem_ctx,
  63                               struct tevent_context *ev,
  64                               const char *iface,
  65                               struct ctdb_connection_list *conn_list)
  66 {
  67         struct tevent_req *req, *subreq;
  68         struct reset_connections_state *state;
  69         int i, ret;
  70
  71         req = tevent_req_create(mem_ctx, &state,
  72                                 struct reset_connections_state);
  73         if (req == NULL) {
  74                 return NULL;
  75         }
  76
  77         state->ev = ev;
  78
  79         if (conn_list->num == 0) {
  80                 /* No connections, done! */
  81                 tevent_req_done(req);
  82                 return tevent_req_post(req, ev);
  83         }
  84
  85         ret = db_hash_init(state, "connections", 2048, DB_HASH_SIMPLE,
  86                            &state->connections);
  87         if (ret != 0) {
  88                 D_ERR("Failed to initialise connection hash (%s)\n",
  89                       strerror(ret));
  90                 tevent_req_error(req, ret);
  91                 return tevent_req_post(req, ev);
  92         }
  93
  94         DBG_DEBUG("Adding %u connections to hash\n", conn_list->num);
  95         for (i = 0; i < conn_list->num; i++) {
  96                 struct ctdb_connection *c = &conn_list->conn[i];
  97
  98                 DBG_DEBUG("Adding connection to hash: %s\n",
  99                           ctdb_connection_to_string(conn_list, c, true));
 100
 101                 /* Connection is stored as a key in the connections hash */
 102                 ret = db_hash_add(state->connections,
 103                                   (uint8_t *)discard_const(c), sizeof(*c),
 104                                   NULL, 0);
 105                 if (ret != 0) {
 106                         D_ERR("Error adding connection to hash (%s)\n",
 107                               strerror(ret));
 108                         tevent_req_error(req, ret);
 109                         return tevent_req_post(req, ev);
 110                 }
 111         }
 112
 113         state->attempts = 0;
 114         state->max_attempts = 50;
 115
 116         state->retry_interval.tv_sec = 0;
 117         state->retry_interval.tv_usec = 100 * 1000;
 118
 119         state->batch_count = 0;
 120         state->batch_size = 300;
 121
 122         state->capture_fd =
 123                 ctdb_sys_open_capture_socket(iface, &state->private_data);
 124         if (state->capture_fd == -1) {
 125                 D_ERR("Failed to open capture socket on iface '%s' (%s)\n",
 126                       iface, strerror(errno));
 127                         tevent_req_error(req, EIO);
 128                         return tevent_req_post(req, ev);
 129         }
 130
 131         state->fde = tevent_add_fd(ev, state, state->capture_fd,
 132                                    TEVENT_FD_READ,
 133                                    reset_connections_capture_tcp_handler,
 134                                    state);
 135         if (tevent_req_nomem(state->fde, req)) {
 136                 return tevent_req_post(req, ev);
 137         }
 138         tevent_fd_set_auto_close(state->fde);
 139
 140         subreq = tevent_wakeup_send(state, ev, tevent_timeval_current_ofs(0,0));
 141         if (tevent_req_nomem(subreq, req)) {
 142                 return tevent_req_post(req, ev);
 143         }
 144         tevent_req_set_callback(subreq, reset_connections_batch, req);
 145
 146         return req;
 147 }
 148
 149 /*
 150   called when we get a read event on the raw socket
 151  */
 152 static void reset_connections_capture_tcp_handler(struct tevent_context *ev,
 153                                                   struct tevent_fd *fde,
 154                                                   uint16_t flags,
 155                                                   void *private_data)
 156 {
 157         struct reset_connections_state *state = talloc_get_type_abort(
 158                 private_data, struct reset_connections_state);
 159         /* 0 the parts that don't get set by ctdb_sys_read_tcp_packet */
 160         struct ctdb_connection conn;
 161         uint32_t ack_seq, seq;
 162         int rst;
 163         uint16_t window;
 164         int ret;
 165
 166         ret = ctdb_sys_read_tcp_packet(state->capture_fd,
 167                                        state->private_data,
 168                                        &conn.server, &conn.client,
 169                                        &ack_seq, &seq, &rst, &window);
 170         if (ret != 0) {
 171                 /* probably a non-tcp ACK packet */
 172                 return;
 173         }
 174
 175         if (window == htons(1234) && (rst || seq == 0)) {
 176                 /* Ignore packets that we sent! */
 177                 D_DEBUG("Ignoring packet: %s, "
 178                         "seq=%"PRIu32", ack_seq=%"PRIu32", "
 179                         "rst=%d, window=%"PRIu16"\n",
 180                         ctdb_connection_to_string(state, &conn, false),
 181                         seq, ack_seq, rst, ntohs(window));
 182                 return;
 183         }
 184
 185         /* Check if this connection is one being reset, if found then delete */
 186         ret = db_hash_delete(state->connections,
 187                              (uint8_t*)&conn, sizeof(conn));
 188         if (ret == ENOENT) {
 189                 /* Packet for some other connection, ignore */
 190                 DBG_DEBUG("Ignoring packet for unknown connection: %s\n",
 191                           ctdb_connection_to_string(state, &conn, true));
 192                 return;
 193         }
 194         if (ret != 0) {
 195                 DBG_WARNING("Internal error (%s)\n", strerror(ret));
 196                 return;
 197         }
 198
 199         D_INFO("Sending a TCP RST to for connection %s\n",
 200                ctdb_connection_to_string(state, &conn, true));
 201
 202         ret = ctdb_sys_send_tcp(&conn.server, &conn.client, ack_seq, seq, 1);
 203         if (ret != 0) {
 204                 DBG_ERR("Error sending TCP RST for connection\n");
 205         }
 206 }
 207
 208 /*
 209  * Called periodically until all sentenced connections have been reset
 210  * or enough attempts have been made
 211  */
 212 static void reset_connections_batch(struct tevent_req *subreq)
 213 {
 214         struct tevent_req *req = tevent_req_callback_data(
 215                 subreq, struct tevent_req);
 216         struct reset_connections_state *state = tevent_req_data(
 217                 req, struct reset_connections_state);
 218         bool status;
 219         int count, ret;
 220
 221         status = tevent_wakeup_recv(subreq);
 222         TALLOC_FREE(subreq);
 223
 224         if (! status) {
 225                 DBG_WARNING("Unexpected error on timer expiry\n");
 226                 /* Keep going... */
 227         }
 228
 229         /* loop over up to batch_size connections sending tickle ACKs */
 230         state->batch_count = 0;
 231         ret = db_hash_traverse(state->connections,
 232                                reset_connections_tickle_connection,
 233                                state, NULL);
 234         if (ret != 0) {
 235                 DBG_WARNING("Unexpected error traversing connections (%s)\n",
 236                             strerror(ret));
 237         }
 238
 239         state->attempts++;
 240
 241         /*
 242          * If there are no more connections to kill or we have tried
 243          * too many times we're finished
 244          */
 245         ret = db_hash_traverse(state->connections, NULL, NULL, &count);
 246         if (ret != 0) {
 247                 /* What now?  Try again until max_attempts reached */
 248                 DBG_WARNING("Unexpected error traversing connections (%s)\n",
 249                             strerror(ret));
 250                 count = 1;
 251         }
 252         if (count == 0 ||
 253             state->attempts >= state->max_attempts) {
 254                 tevent_req_done(req);
 255                 return;
 256         }
 257
 258         /* Schedule next attempt */
 259         subreq = tevent_wakeup_send(state, state->ev,
 260                                     tevent_timeval_current_ofs(
 261                                             state->retry_interval.tv_sec,
 262                                             state->retry_interval.tv_usec));
 263         if (tevent_req_nomem(subreq, req)) {
 264                 return;
 265         }
 266         tevent_req_set_callback(subreq, reset_connections_batch, req);
 267 }
 268
 269 static int reset_connections_tickle_connection(
 270                                         uint8_t *keybuf, size_t keylen,
 271                                         uint8_t *databuf, size_t datalen,
 272                                         void *private_data)
 273 {
 274         struct reset_connections_state *state = talloc_get_type_abort(
 275                 private_data, struct reset_connections_state);
 276         struct ctdb_connection *conn;
 277         int ret;
 278
 279         if (keylen != sizeof(*conn)) {
 280                 DBG_WARNING("Unexpected data in connection hash\n");
 281                 return 0;
 282         }
 283
 284         conn = (struct ctdb_connection *)keybuf;
 285
 286         state->batch_count++;
 287         if (state->batch_count > state->batch_size) {
 288                 /* Terminate the traverse */
 289                 return 1;
 290         }
 291
 292         DBG_DEBUG("Sending tickle ACK for connection '%s'\n",
 293                   ctdb_connection_to_string(state, conn, true));
 294         ret = ctdb_sys_send_tcp(&conn->server, &conn->client, 0, 0, 0);
 295         if (ret != 0) {
 296                 DBG_ERR("Error sending tickle ACK\n");
 297                 /* continue */
 298         }
 299
 300         return 0;
 301 }
 302
 303 static bool reset_connections_recv(struct tevent_req *req, int *perr)
 304 {
 305         int err;
 306
 307         if (tevent_req_is_unix_error(req, &err)) {
 308                 if (perr != NULL) {
 309                         *perr = err;
 310                 }
 311                 return false;
 312         }
 313
 314         return true;
 315 }
 316
 317 static void usage(const char *prog)
 318 {
 319         printf("usage: %s <interface> [ <srcip:port> <dstip:port> ]\n", prog);
 320         exit(1);
 321 }
 322
 323 int main(int argc, char **argv)
 324 {
 325         struct ctdb_connection conn;
 326         struct tevent_context *ev = NULL;
 327         struct TALLOC_CONTEXT *mem_ctx = NULL;
 328         struct ctdb_connection_list *conn_list = NULL;
 329         const char *t;
 330         struct tevent_req *req;
 331         int debug_level;
 332         bool status;
 333         int ret;
 334
 335         /* Set the debug level */
 336         t = getenv("CTDB_DEBUGLEVEL");
 337         if (t != NULL) {
 338                 if (debug_level_parse(t, &debug_level)) {
 339                         DEBUGLEVEL = debug_level;
 340                 } else {
 341                         DEBUGLEVEL = DEBUG_ERR;
 342                 }
 343         }
 344
 345         if (argc != 2 && argc != 4) {
 346                 usage(argv[0]);
 347         }
 348
 349         if (argc == 4) {
 350                 ret = ctdb_sock_addr_from_string(argv[2], &conn.client, true);
 351                 if (ret != 0) {
 352                         D_ERR("Bad IP:port '%s'\n", argv[2]);
 353                         goto fail;
 354                 }
 355
 356                 ret = ctdb_sock_addr_from_string(argv[3], &conn.server, true);
 357                 if (ret != 0) {
 358                         D_ERR("Bad IP:port '%s'\n", argv[3]);
 359                         goto fail;
 360                 }
 361
 362
 363                 conn_list = talloc_zero(mem_ctx, struct ctdb_connection_list);
 364                 if (conn_list == NULL) {
 365                         ret = ENOMEM;
 366                         DBG_ERR("Internal error (%s)\n", strerror(ret));
 367                         goto fail;
 368                 }
 369                 ret = ctdb_connection_list_add(conn_list, &conn);
 370                 if (ret != 0) {
 371                         DBG_ERR("Internal error (%s)\n", strerror(ret));
 372                         goto fail;
 373                 }
 374         } else {
 375                 ret = ctdb_connection_list_read(mem_ctx, true, &conn_list);
 376                 if (ret != 0) {
 377                         D_ERR("Unable to parse connections (%s)\n",
 378                               strerror(ret));
 379                         goto fail;
 380                 }
 381         }
 382
 383         mem_ctx = talloc_new(NULL);
 384         if (mem_ctx == NULL) {
 385                 DEBUG(DEBUG_ERR, (__location__ " out of memory\n"));
 386                 goto fail;
 387         }
 388
 389         ev = tevent_context_init(mem_ctx);
 390         if (ev == NULL) {
 391                 DEBUG(DEBUG_ERR, ("Failed to initialise tevent\n"));
 392                 goto fail;
 393         }
 394
 395         req = reset_connections_send(mem_ctx, ev, argv[1], conn_list);
 396         if (req == NULL) {
 397                 goto fail;
 398         }
 399
 400         tevent_req_poll(req, ev);
 401
 402         status = reset_connections_recv(req, &ret);
 403         if (! status) {
 404                 D_ERR("Failed to kill connections (%s)\n", strerror(ret));
 405                 goto fail;
 406         }
 407
 408         talloc_free(mem_ctx);
 409
 410         return 0;
 411
 412 fail:
 413         TALLOC_FREE(mem_ctx);
 414         return -1;
 415 }