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comparison netio.c @ 1857:6022df862942

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Use DSCP for IP QoS traffic classes The previous TOS values are deprecated and not used by modern traffic classifiers. This sets AF21 for "interactive" traffic (with a tty). Non-tty traffic sets AF11 - that indicates high throughput but is not lowest priority (which would be CS1 or LE). This differs from the CS1 used by OpenSSH, it lets interactive git over SSH have higher priority than background least effort traffic. Dropbear's settings here should be suitable with the diffservs used by CAKE qdisc.
author Matt Johnston <matt@ucc.asn.au>
date Tue, 25 Jan 2022 17:32:20 +0800
parents 4983a6bc1f51
children ed3326f21888 1d86a58fb52d
comparison
equal deleted inserted replaced
1856:8f28519e34b0 1857:6022df862942
361 #endif 361 #endif
362 362
363 void set_sock_priority(int sock, enum dropbear_prio prio) { 363 void set_sock_priority(int sock, enum dropbear_prio prio) {
364 364
365 int rc; 365 int rc;
366 #ifdef IPTOS_LOWDELAY 366 int val;
367 int iptos_val = 0;
368 #endif
369 #ifdef HAVE_LINUX_PKT_SCHED_H
370 int so_prio_val = 0;
371 #endif
372 367
373 #if DROPBEAR_FUZZ 368 #if DROPBEAR_FUZZ
374 if (fuzz.fuzzing) { 369 if (fuzz.fuzzing) {
375 TRACE(("fuzzing skips set_sock_prio")) 370 TRACE(("fuzzing skips set_sock_prio"))
376 return; 371 return;
377 } 372 }
378 #endif 373 #endif
379
380 /* Don't log ENOTSOCK errors so that this can harmlessly be called 374 /* Don't log ENOTSOCK errors so that this can harmlessly be called
381 * on a client '-J' proxy pipe */ 375 * on a client '-J' proxy pipe */
382 376
383 /* set the TOS bit for either ipv4 or ipv6 */ 377 #ifdef IPTOS_DSCP_AF21
384 #ifdef IPTOS_LOWDELAY 378 /* Set the DSCP field for outbound IP packet priority.
379 rfc4594 has some guidance to meanings.
380
381 We set AF21 as "Low-Latency" class for interactive (tty session).
382 Set AF11 "High-Throughput" for bulk data (which includes things
383 such as git over ssh). We usually want higher priority than
384 CS1/LE least effort.
385
386 OpenSSH at present uses AF21/CS1, rationale
387 https://cvsweb.openbsd.org/src/usr.bin/ssh/readconf.c#rev1.284
388
389 Old Dropbear/OpenSSH and Debian/Ubuntu OpenSSH (at Jan 2022) use
390 IPTOS_LOWDELAY/IPTOS_THROUGHPUT
391 */
385 if (prio == DROPBEAR_PRIO_LOWDELAY) { 392 if (prio == DROPBEAR_PRIO_LOWDELAY) {
386 iptos_val = IPTOS_LOWDELAY; 393 val = IPTOS_DSCP_AF21;
387 } else if (prio == DROPBEAR_PRIO_BULK) { 394 } else if (prio == DROPBEAR_PRIO_BULK) {
388 iptos_val = IPTOS_THROUGHPUT; 395 val = IPTOS_DSCP_AF11;
396 } else {
397 val = 0; /* default */
389 } 398 }
390 #if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS) 399 #if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS)
391 rc = setsockopt(sock, IPPROTO_IPV6, IPV6_TCLASS, (void*)&iptos_val, sizeof(iptos_val)); 400 rc = setsockopt(sock, IPPROTO_IPV6, IPV6_TCLASS, (void*)&val, sizeof(val));
392 if (rc < 0 && errno != ENOTSOCK) { 401 if (rc < 0 && errno != ENOTSOCK) {
393 TRACE(("Couldn't set IPV6_TCLASS (%s)", strerror(errno))); 402 TRACE(("Couldn't set IPV6_TCLASS (%s)", strerror(errno)));
394 } 403 }
395 #endif 404 #endif
396 rc = setsockopt(sock, IPPROTO_IP, IP_TOS, (void*)&iptos_val, sizeof(iptos_val)); 405 rc = setsockopt(sock, IPPROTO_IP, IP_TOS, (void*)&val, sizeof(val));
397 if (rc < 0 && errno != ENOTSOCK) { 406 if (rc < 0 && errno != ENOTSOCK) {
398 TRACE(("Couldn't set IP_TOS (%s)", strerror(errno))); 407 TRACE(("Couldn't set IP_TOS (%s)", strerror(errno)));
399 } 408 }
400 #endif 409 #endif
401 410
402 #ifdef HAVE_LINUX_PKT_SCHED_H 411 #ifdef HAVE_LINUX_PKT_SCHED_H
412 /* Set scheduling priority within the local Linux network stack */
403 if (prio == DROPBEAR_PRIO_LOWDELAY) { 413 if (prio == DROPBEAR_PRIO_LOWDELAY) {
404 so_prio_val = TC_PRIO_INTERACTIVE; 414 val = TC_PRIO_INTERACTIVE;
405 } else if (prio == DROPBEAR_PRIO_BULK) { 415 } else if (prio == DROPBEAR_PRIO_BULK) {
406 so_prio_val = TC_PRIO_BULK; 416 val = TC_PRIO_BULK;
417 } else {
418 val = 0;
407 } 419 }
408 /* linux specific, sets QoS class. see tc-prio(8) */ 420 /* linux specific, sets QoS class. see tc-prio(8) */
409 rc = setsockopt(sock, SOL_SOCKET, SO_PRIORITY, (void*) &so_prio_val, sizeof(so_prio_val)); 421 rc = setsockopt(sock, SOL_SOCKET, SO_PRIORITY, (void*) &val, sizeof(val));
410 if (rc < 0 && errno != ENOTSOCK) { 422 if (rc < 0 && errno != ENOTSOCK) {
411 TRACE(("Couldn't set SO_PRIORITY (%s)", strerror(errno))) 423 TRACE(("Couldn't set SO_PRIORITY (%s)", strerror(errno)))
412 } 424 }
413 #endif 425 #endif
414 426