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Rewrite dns_resolver and dns_request to use netmgr timeouts

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- The `timeout_action` parameter to dns_dispatch_addresponse() been
  replaced with a netmgr callback that is called when a dispatch read
  times out.  this callback may optionally reset the read timer and
  resume reading.

- Added a function to convert isc_interval to milliseconds; this is used
  to translate fctx->interval into a value that can be passed to
  dns_dispatch_addresponse() as the timeout.

- Note that netmgr timeouts are accurate to the millisecond, so code to
  check whether a timeout has been reached cannot rely on microsecond
  accuracy.

- If serve-stale is configured, then a timeout received by the resolver
  may trigger it to return stale data, and then resume waiting for the
  read timeout. this is no longer based on a separate stale timer.

- The code for canceling requests in request.c has been altered so that
  it can run asynchronously.

- TCP timeout events apply to the dispatch, which may be shared by
  multiple queries.  since in the event of a timeout we have no query ID
  to use to identify the resp we wanted, we now just send the timeout to
  the oldest query that was pending.

- There was some additional refactoring in the resolver: combining
  fctx_join() and fctx_try_events() into one function to reduce code
  duplication, and using fixednames in fetchctx and fetchevent.

- Incidental fix: new_adbaddrinfo() can't return NULL anymore, so the
  code can be simplified.
This commit is contained in:
Evan Hunt
2021-04-22 18:58:01 -07:00
parent 308bc46a59
commit 08ce69a0ea
14 changed files with 601 additions and 827 deletions
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23
lib/dns/adb.c
View File

@@ -2237,11 +2237,9 @@ copy_namehook_lists(dns_adb_t *adb, dns_adbfind_t *find,
find->options |= DNS_ADBFIND_LAMEPRUNED;
goto nextv4;
}
addrinfo = new_adbaddrinfo(adb, entry, find->port);
if (addrinfo == NULL) {
find->partial_result |= DNS_ADBFIND_INET;
goto out;
}
/*
* Found a valid entry. Add it to the find's list.
*/
@@ -2275,10 +2273,7 @@ copy_namehook_lists(dns_adb_t *adb, dns_adbfind_t *find,
goto nextv6;
}
addrinfo = new_adbaddrinfo(adb, entry, find->port);
if (addrinfo == NULL) {
find->partial_result |= DNS_ADBFIND_INET6;
goto out;
}
/*
* Found a valid entry. Add it to the find's list.
*/
@@ -2292,7 +2287,6 @@ copy_namehook_lists(dns_adb_t *adb, dns_adbfind_t *find,
}
}
out:
if (bucket != DNS_ADB_INVALIDBUCKET) {
UNLOCK(&adb->entrylocks[bucket]);
}
@@ -3962,8 +3956,7 @@ fetch_callback(isc_task_t *task, isc_event_t *ev) {
dev->rdataset->ttl = ttlclamp(dev->rdataset->ttl);
clean_target(adb, &name->target);
name->expire_target = INT_MAX;
result = set_target(adb, &name->name,
dns_fixedname_name(&dev->foundname),
result = set_target(adb, &name->name, dev->foundname,
dev->rdataset, &name->target);
if (result == ISC_R_SUCCESS) {
DP(NCACHE_LEVEL,
@@ -4533,12 +4526,8 @@ dns_adb_findaddrinfo(dns_adb_t *adb, const isc_sockaddr_t *sa,
port = isc_sockaddr_getport(sa);
addr = new_adbaddrinfo(adb, entry, port);
if (addr == NULL) {
result = ISC_R_NOMEMORY;
} else {
inc_entry_refcnt(adb, entry, false);
*addrp = addr;
}
inc_entry_refcnt(adb, entry, false);
*addrp = addr;
unlock:
UNLOCK(&adb->entrylocks[bucket]);