1 /* $NetBSD: qmgr_transport.c,v 1.2 2017/02/14 01:16:46 christos Exp $ */ 2 3 /*++ 4 /* NAME 5 /* qmgr_transport 3 6 /* SUMMARY 7 /* per-transport data structures 8 /* SYNOPSIS 9 /* #include "qmgr.h" 10 /* 11 /* QMGR_TRANSPORT *qmgr_transport_create(name) 12 /* const char *name; 13 /* 14 /* QMGR_TRANSPORT *qmgr_transport_find(name) 15 /* const char *name; 16 /* 17 /* QMGR_TRANSPORT *qmgr_transport_select() 18 /* 19 /* void qmgr_transport_alloc(transport, notify) 20 /* QMGR_TRANSPORT *transport; 21 /* void (*notify)(QMGR_TRANSPORT *transport, VSTREAM *fp); 22 /* 23 /* void qmgr_transport_throttle(transport, dsn) 24 /* QMGR_TRANSPORT *transport; 25 /* DSN *dsn; 26 /* 27 /* void qmgr_transport_unthrottle(transport) 28 /* QMGR_TRANSPORT *transport; 29 /* DESCRIPTION 30 /* This module organizes the world by message transport type. 31 /* Each transport can have zero or more destination queues 32 /* associated with it. 33 /* 34 /* qmgr_transport_create() instantiates a data structure for the 35 /* named transport type. 36 /* 37 /* qmgr_transport_find() looks up an existing message transport 38 /* data structure. 39 /* 40 /* qmgr_transport_select() attempts to find a transport that 41 /* has messages pending delivery. This routine implements 42 /* round-robin search among transports. 43 /* 44 /* qmgr_transport_alloc() allocates a delivery process for the 45 /* specified transport type. Allocation is performed asynchronously. 46 /* When a process becomes available, the application callback routine 47 /* is invoked with as arguments the transport and a stream that 48 /* is connected to a delivery process. It is an error to call 49 /* qmgr_transport_alloc() while delivery process allocation for 50 /* the same transport is in progress. 51 /* 52 /* qmgr_transport_throttle blocks further allocation of delivery 53 /* processes for the named transport. Attempts to throttle a 54 /* throttled transport are ignored. 55 /* 56 /* qmgr_transport_unthrottle() undoes qmgr_transport_throttle(). 57 /* Attempts to unthrottle a non-throttled transport are ignored. 58 /* DIAGNOSTICS 59 /* Panic: consistency check failure. Fatal: out of memory. 60 /* LICENSE 61 /* .ad 62 /* .fi 63 /* The Secure Mailer license must be distributed with this software. 64 /* AUTHOR(S) 65 /* Wietse Venema 66 /* IBM T.J. Watson Research 67 /* P.O. Box 704 68 /* Yorktown Heights, NY 10598, USA 69 /* 70 /* Wietse Venema 71 /* Google, Inc. 72 /* 111 8th Avenue 73 /* New York, NY 10011, USA 74 /*--*/ 75 76 /* System library. */ 77 78 #include <sys_defs.h> 79 #include <unistd.h> 80 81 #include <sys/time.h> /* FD_SETSIZE */ 82 #include <sys/types.h> /* FD_SETSIZE */ 83 #include <unistd.h> /* FD_SETSIZE */ 84 85 #ifdef USE_SYS_SELECT_H 86 #include <sys/select.h> /* FD_SETSIZE */ 87 #endif 88 89 /* Utility library. */ 90 91 #include <msg.h> 92 #include <htable.h> 93 #include <events.h> 94 #include <mymalloc.h> 95 #include <vstream.h> 96 #include <iostuff.h> 97 98 /* Global library. */ 99 100 #include <mail_proto.h> 101 #include <recipient_list.h> 102 #include <mail_conf.h> 103 #include <mail_params.h> 104 105 /* Application-specific. */ 106 107 #include "qmgr.h" 108 109 HTABLE *qmgr_transport_byname; /* transport by name */ 110 QMGR_TRANSPORT_LIST qmgr_transport_list;/* transports, round robin */ 111 112 /* 113 * A local structure to remember a delivery process allocation request. 114 */ 115 typedef struct QMGR_TRANSPORT_ALLOC QMGR_TRANSPORT_ALLOC; 116 117 struct QMGR_TRANSPORT_ALLOC { 118 QMGR_TRANSPORT *transport; /* transport context */ 119 VSTREAM *stream; /* delivery service stream */ 120 QMGR_TRANSPORT_ALLOC_NOTIFY notify; /* application call-back routine */ 121 }; 122 123 /* 124 * Connections to delivery agents are managed asynchronously. Each delivery 125 * agent connection goes through multiple wait states: 126 * 127 * - With Linux/Solaris and old queue manager implementations only, wait for 128 * the server to invoke accept(). 129 * 130 * - Wait for the delivery agent's announcement that it is ready to receive a 131 * delivery request. 132 * 133 * - Wait for the delivery request completion status. 134 * 135 * Older queue manager implementations had only one pending delivery agent 136 * connection per transport. With low-latency destinations, the output rates 137 * were reduced on Linux/Solaris systems that had the extra wait state. 138 * 139 * To maximize delivery agent output rates with low-latency destinations, the 140 * following changes were made to the queue manager by the end of the 2.4 141 * development cycle: 142 * 143 * - The Linux/Solaris accept() wait state was eliminated. 144 * 145 * - A pipeline was implemented for pending delivery agent connections. The 146 * number of pending delivery agent connections was increased from one to 147 * two: the number of before-delivery wait states, plus one extra pipeline 148 * slot to prevent the pipeline from stalling easily. Increasing the 149 * pipeline much further actually hurt performance. 150 * 151 * - To reduce queue manager disk competition with delivery agents, the queue 152 * scanning algorithm was modified to import only one message per interrupt. 153 * The incoming and deferred queue scans now happen on alternate interrupts. 154 * 155 * Simplistically reasoned, a non-zero (incoming + active) queue length is 156 * equivalent to a time shift for mail deliveries; this is undesirable when 157 * delivery agents are not fully utilized. 158 * 159 * On the other hand a non-empty active queue is what allows us to do clever 160 * things such as queue file prefetch, concurrency windows, and connection 161 * caching; the idea is that such "thinking time" is affordable only after 162 * the output channels are maxed out. 163 */ 164 #ifndef QMGR_TRANSPORT_MAX_PEND 165 #define QMGR_TRANSPORT_MAX_PEND 2 166 #endif 167 168 /* 169 * Important note on the _transport_rate_delay implementation: after 170 * qmgr_transport_alloc() sets the QMGR_TRANSPORT_STAT_RATE_LOCK flag, all 171 * code paths must directly or indirectly invoke qmgr_transport_unthrottle() 172 * or qmgr_transport_throttle(). Otherwise, transports with non-zero 173 * _transport_rate_delay will become stuck. 174 */ 175 176 /* qmgr_transport_unthrottle_wrapper - in case (char *) != (struct *) */ 177 178 static void qmgr_transport_unthrottle_wrapper(int unused_event, void *context) 179 { 180 qmgr_transport_unthrottle((QMGR_TRANSPORT *) context); 181 } 182 183 /* qmgr_transport_unthrottle - open the throttle */ 184 185 void qmgr_transport_unthrottle(QMGR_TRANSPORT *transport) 186 { 187 const char *myname = "qmgr_transport_unthrottle"; 188 189 /* 190 * This routine runs after expiration of the timer set by 191 * qmgr_transport_throttle(), or whenever a delivery transport has been 192 * used without malfunction. In either case, we enable delivery again if 193 * the transport was throttled. We always reset the transport rate lock. 194 */ 195 if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0) { 196 if (msg_verbose) 197 msg_info("%s: transport %s", myname, transport->name); 198 transport->flags &= ~QMGR_TRANSPORT_STAT_DEAD; 199 if (transport->dsn == 0) 200 msg_panic("%s: transport %s: null reason", 201 myname, transport->name); 202 dsn_free(transport->dsn); 203 transport->dsn = 0; 204 event_cancel_timer(qmgr_transport_unthrottle_wrapper, 205 (void *) transport); 206 } 207 if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) 208 transport->flags &= ~QMGR_TRANSPORT_STAT_RATE_LOCK; 209 } 210 211 /* qmgr_transport_throttle - disable delivery process allocation */ 212 213 void qmgr_transport_throttle(QMGR_TRANSPORT *transport, DSN *dsn) 214 { 215 const char *myname = "qmgr_transport_throttle"; 216 217 /* 218 * We are unable to connect to a deliver process for this type of message 219 * transport. Instead of hosing the system by retrying in a tight loop, 220 * back off and disable this transport type for a while. 221 */ 222 if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) == 0) { 223 if (msg_verbose) 224 msg_info("%s: transport %s: status: %s reason: %s", 225 myname, transport->name, dsn->status, dsn->reason); 226 transport->flags |= QMGR_TRANSPORT_STAT_DEAD; 227 if (transport->dsn) 228 msg_panic("%s: transport %s: spurious reason: %s", 229 myname, transport->name, transport->dsn->reason); 230 transport->dsn = DSN_COPY(dsn); 231 event_request_timer(qmgr_transport_unthrottle_wrapper, 232 (void *) transport, var_transport_retry_time); 233 } 234 } 235 236 /* qmgr_transport_abort - transport connect watchdog */ 237 238 static void qmgr_transport_abort(int unused_event, void *context) 239 { 240 QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context; 241 242 msg_fatal("timeout connecting to transport: %s", alloc->transport->name); 243 } 244 245 /* qmgr_transport_rate_event - delivery process availability notice */ 246 247 static void qmgr_transport_rate_event(int unused_event, void *context) 248 { 249 QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context; 250 251 alloc->notify(alloc->transport, alloc->stream); 252 myfree((void *) alloc); 253 } 254 255 /* qmgr_transport_event - delivery process availability notice */ 256 257 static void qmgr_transport_event(int unused_event, void *context) 258 { 259 QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context; 260 261 /* 262 * This routine notifies the application when the request given to 263 * qmgr_transport_alloc() completes. 264 */ 265 if (msg_verbose) 266 msg_info("transport_event: %s", alloc->transport->name); 267 268 /* 269 * Connection request completed. Stop the watchdog timer. 270 */ 271 event_cancel_timer(qmgr_transport_abort, context); 272 273 /* 274 * Disable further read events that end up calling this function, and 275 * free up this pending connection pipeline slot. 276 */ 277 if (alloc->stream) { 278 event_disable_readwrite(vstream_fileno(alloc->stream)); 279 non_blocking(vstream_fileno(alloc->stream), BLOCKING); 280 } 281 alloc->transport->pending -= 1; 282 283 /* 284 * Notify the requestor. 285 */ 286 if (alloc->transport->xport_rate_delay > 0) { 287 if ((alloc->transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) == 0) 288 msg_panic("transport_event: missing rate lock for transport %s", 289 alloc->transport->name); 290 event_request_timer(qmgr_transport_rate_event, (void *) alloc, 291 alloc->transport->xport_rate_delay); 292 } else { 293 alloc->notify(alloc->transport, alloc->stream); 294 myfree((void *) alloc); 295 } 296 } 297 298 /* qmgr_transport_select - select transport for allocation */ 299 300 QMGR_TRANSPORT *qmgr_transport_select(void) 301 { 302 QMGR_TRANSPORT *xport; 303 QMGR_QUEUE *queue; 304 int need; 305 306 /* 307 * If we find a suitable transport, rotate the list of transports to 308 * effectuate round-robin selection. See similar selection code in 309 * qmgr_queue_select(). 310 * 311 * This function is called repeatedly until all transports have maxed out 312 * the number of pending delivery agent connections, until all delivery 313 * agent concurrency windows are maxed out, or until we run out of "todo" 314 * queue entries. 315 */ 316 #define MIN5af51743e4eef(x, y) ((x) < (y) ? (x) : (y)) 317 318 for (xport = qmgr_transport_list.next; xport; xport = xport->peers.next) { 319 if ((xport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0 320 || (xport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) != 0 321 || xport->pending >= QMGR_TRANSPORT_MAX_PEND) 322 continue; 323 need = xport->pending + 1; 324 for (queue = xport->queue_list.next; queue; queue = queue->peers.next) { 325 if (QMGR_QUEUE_READY(queue) == 0) 326 continue; 327 if ((need -= MIN5af51743e4eef(queue->window - queue->busy_refcount, 328 queue->todo_refcount)) <= 0) { 329 QMGR_LIST_ROTATE(qmgr_transport_list, xport); 330 if (msg_verbose) 331 msg_info("qmgr_transport_select: %s", xport->name); 332 return (xport); 333 } 334 } 335 } 336 return (0); 337 } 338 339 /* qmgr_transport_alloc - allocate delivery process */ 340 341 void qmgr_transport_alloc(QMGR_TRANSPORT *transport, QMGR_TRANSPORT_ALLOC_NOTIFY notify) 342 { 343 QMGR_TRANSPORT_ALLOC *alloc; 344 345 /* 346 * Sanity checks. 347 */ 348 if (transport->flags & QMGR_TRANSPORT_STAT_DEAD) 349 msg_panic("qmgr_transport: dead transport: %s", transport->name); 350 if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) 351 msg_panic("qmgr_transport: rate-locked transport: %s", transport->name); 352 if (transport->pending >= QMGR_TRANSPORT_MAX_PEND) 353 msg_panic("qmgr_transport: excess allocation: %s", transport->name); 354 355 /* 356 * When this message delivery transport is rate-limited, do not select it 357 * again before the end of a message delivery transaction. 358 */ 359 if (transport->xport_rate_delay > 0) 360 transport->flags |= QMGR_TRANSPORT_STAT_RATE_LOCK; 361 362 /* 363 * Connect to the well-known port for this delivery service, and wake up 364 * when a process announces its availability. Allow only a limited number 365 * of delivery process allocation attempts for this transport. In case of 366 * problems, back off. Do not hose the system when it is in trouble 367 * already. 368 * 369 * Use non-blocking connect(), so that Linux won't block the queue manager 370 * until the delivery agent calls accept(). 371 * 372 * When the connection to delivery agent cannot be completed, notify the 373 * event handler so that it can throttle the transport and defer the todo 374 * queues, just like it does when communication fails *after* connection 375 * completion. 376 * 377 * Before Postfix 2.4, the event handler was not invoked after connect() 378 * error, and mail was not deferred. Because of this, mail would be stuck 379 * in the active queue after triggering a "connection refused" condition. 380 */ 381 alloc = (QMGR_TRANSPORT_ALLOC *) mymalloc(sizeof(*alloc)); 382 alloc->transport = transport; 383 alloc->notify = notify; 384 transport->pending += 1; 385 if ((alloc->stream = mail_connect(MAIL_CLASS_PRIVATE, transport->name, 386 NON_BLOCKING)) == 0) { 387 msg_warn("connect to transport %s/%s: %m", 388 MAIL_CLASS_PRIVATE, transport->name); 389 event_request_timer(qmgr_transport_event, (void *) alloc, 0); 390 return; 391 } 392 #if (EVENTS_STYLE != EVENTS_STYLE_SELECT) && defined(CA_VSTREAM_CTL_DUPFD) 393 #ifndef THRESHOLD_FD_WORKAROUND 394 #define THRESHOLD_FD_WORKAROUND 128 395 #endif 396 vstream_control(alloc->stream, 397 CA_VSTREAM_CTL_DUPFD(THRESHOLD_FD_WORKAROUND), 398 CA_VSTREAM_CTL_END); 399 #endif 400 event_enable_read(vstream_fileno(alloc->stream), qmgr_transport_event, 401 (void *) alloc); 402 403 /* 404 * Guard against broken systems. 405 */ 406 event_request_timer(qmgr_transport_abort, (void *) alloc, 407 var_daemon_timeout); 408 } 409 410 /* qmgr_transport_create - create transport instance */ 411 412 QMGR_TRANSPORT *qmgr_transport_create(const char *name) 413 { 414 QMGR_TRANSPORT *transport; 415 416 if (htable_find(qmgr_transport_byname, name) != 0) 417 msg_panic("qmgr_transport_create: transport exists: %s", name); 418 transport = (QMGR_TRANSPORT *) mymalloc(sizeof(QMGR_TRANSPORT)); 419 transport->flags = 0; 420 transport->pending = 0; 421 transport->name = mystrdup(name); 422 423 /* 424 * Use global configuration settings or transport-specific settings. 425 */ 426 transport->dest_concurrency_limit = 427 get_mail_conf_int2(name, _DEST_CON_LIMIT, 428 var_dest_con_limit, 0, 0); 429 transport->recipient_limit = 430 get_mail_conf_int2(name, _DEST_RCPT_LIMIT, 431 var_dest_rcpt_limit, 0, 0); 432 transport->init_dest_concurrency = 433 get_mail_conf_int2(name, _INIT_DEST_CON, 434 var_init_dest_concurrency, 1, 0); 435 transport->xport_rate_delay = get_mail_conf_time2(name, _XPORT_RATE_DELAY, 436 var_xport_rate_delay, 437 's', 0, 0); 438 transport->rate_delay = get_mail_conf_time2(name, _DEST_RATE_DELAY, 439 var_dest_rate_delay, 440 's', 0, 0); 441 442 if (transport->rate_delay > 0) 443 transport->dest_concurrency_limit = 1; 444 if (transport->dest_concurrency_limit != 0 445 && transport->dest_concurrency_limit < transport->init_dest_concurrency) 446 transport->init_dest_concurrency = transport->dest_concurrency_limit; 447 448 transport->queue_byname = htable_create(0); 449 QMGR_LIST_INIT(transport->queue_list); 450 transport->dsn = 0; 451 qmgr_feedback_init(&transport->pos_feedback, name, _CONC_POS_FDBACK, 452 VAR_CONC_POS_FDBACK, var_conc_pos_feedback); 453 qmgr_feedback_init(&transport->neg_feedback, name, _CONC_NEG_FDBACK, 454 VAR_CONC_NEG_FDBACK, var_conc_neg_feedback); 455 transport->fail_cohort_limit = 456 get_mail_conf_int2(name, _CONC_COHORT_LIM, 457 var_conc_cohort_limit, 0, 0); 458 if (qmgr_transport_byname == 0) 459 qmgr_transport_byname = htable_create(10); 460 htable_enter(qmgr_transport_byname, name, (void *) transport); 461 QMGR_LIST_APPEND(qmgr_transport_list, transport); 462 if (msg_verbose) 463 msg_info("qmgr_transport_create: %s concurrency %d recipients %d", 464 transport->name, transport->dest_concurrency_limit, 465 transport->recipient_limit); 466 return (transport); 467 } 468 469 /* qmgr_transport_find - find transport instance */ 470 471 QMGR_TRANSPORT *qmgr_transport_find(const char *name) 472 { 473 return ((QMGR_TRANSPORT *) htable_find(qmgr_transport_byname, name)); 474 } 475