static int
dnsTimeoutHandler(TimeEventHandlerPtr event)
{
DnsQueryPtr query = *(DnsQueryPtr*)event->data;
ObjectPtr object = query->object;
int rc;
/* People are reporting that this does happen. And I have no idea why. */
if(!queryInFlight(query)) {
do_log(L_ERROR, "BUG: timing out martian query (%s, flags: 0x%x).\n",
scrub(query->name->string), (unsigned)object->flags);
return 1;
}
query->timeout = MAX(10, query->timeout * 2);
if(query->timeout > dnsMaxTimeout) {
abortObject(object, 501, internAtom("Timeout"));
goto fail;
} else {
rc = sendQuery(query);
if(rc < 0) {
if(rc != -EWOULDBLOCK && rc != -EAGAIN && rc != -ENOBUFS) {
abortObject(object, 501,
internAtomError(-rc,
"Couldn't send DNS query"));
goto fail;
}
/* else let it timeout */
}
query->timeout_handler =
scheduleTimeEvent(query->timeout, dnsTimeoutHandler,
sizeof(query), &query);
if(query->timeout_handler == NULL) {
do_log(L_ERROR, "Couldn't schedule DNS timeout handler.\n");
abortObject(object, 501,
internAtom("Couldn't schedule DNS timeout handler"));
goto fail;
}
return 1;
}
fail:
removeQuery(query);
object->flags &= ~OBJECT_INPROGRESS;
if(query->inet4) releaseAtom(query->inet4);
if(query->inet6) releaseAtom(query->inet6);
free(query);
releaseNotifyObject(object);
return 1;
}
int
specialRequestHandler(int status,
FdEventHandlerPtr event, StreamRequestPtr srequest)
{
SpecialRequestPtr request = srequest->data;
int rc;
int killed = 0;
(void)event;
if (status < 0) {
kill(request->pid, SIGTERM);
killed = 1;
request->object->flags &= ~OBJECT_INPROGRESS;
abortObject(request->object, 502,
internAtomError(-status,
"Couldn't read from client"));
goto done;
}
if (srequest->offset > 0) {
rc = objectAddData(request->object, request->buf,
request->offset, srequest->offset);
if (rc < 0) {
kill(request->pid, SIGTERM);
killed = 1;
request->object->flags &= ~OBJECT_INPROGRESS;
abortObject(request->object, 503,
internAtom
("Couldn't add data to connection"));
goto done;
}
request->offset += srequest->offset;
}
if (status) {
request->object->flags &= ~OBJECT_INPROGRESS;
request->object->length = request->object->size;
goto done;
}
if (request->object->refcount <= 1) {
kill(request->pid, SIGTERM);
killed = 1;
request->object->flags &= ~OBJECT_INPROGRESS;
abortObject(request->object, 500, internAtom("Aborted"));
goto done;
}
notifyObject(request->object);
do_stream(IO_READ | IO_NOTNOW, request->fd, 0, request->buf, CHUNK_SIZE,
specialRequestHandler, request);
return 1;
done:
close(request->fd);
dispose_chunk(request->buf);
releaseNotifyObject(request->object);
do {
rc = waitpid(request->pid, &status, 0);
} while (rc < 0 && errno == EINTR);
if (rc < 0) {
do_log(L_ERROR, "Wait for %d: %d\n", (int)request->pid, errno);
} else {
int normal =
(WIFEXITED(status) && WEXITSTATUS(status) == 0) ||
(killed && WIFSIGNALED(status)
&& WTERMSIG(status) == SIGTERM);
char *reason =
WIFEXITED(status) ? "with status" : WIFSIGNALED(status) ?
"on signal" : "with unknown status";
int value =
WIFEXITED(status) ? WEXITSTATUS(status) :
WIFSIGNALED(status) ? WTERMSIG(status) : status;
do_log(normal ? D_CHILD : L_ERROR, "Child %d exited %s %d.\n",
(int)request->pid, reason, value);
}
free(request);
return 1;
}
static int
dnsGethostbynameFallback(int id, AtomPtr message)
{
DnsQueryPtr query, previous;
ObjectPtr object;
if(inFlightDnsQueries == NULL) {
releaseAtom(message);
return 1;
}
query = NULL;
if(id < 0 || inFlightDnsQueries->id == id) {
previous = NULL;
query = inFlightDnsQueries;
} else {
previous = inFlightDnsQueries;
while(previous->next) {
if(previous->next->id == id) {
query = previous->next;
break;
}
previous = previous->next;
}
if(!query) {
previous = NULL;
query = inFlightDnsQueries;
}
}
if(previous == NULL) {
inFlightDnsQueries = query->next;
if(inFlightDnsQueries == NULL)
inFlightDnsQueriesLast = NULL;
} else {
previous->next = query->next;
if(query->next == NULL)
inFlightDnsQueriesLast = NULL;
}
object = makeObject(OBJECT_DNS, query->name->string, query->name->length,
1, 0, NULL, NULL);
if(!object) {
do_log(L_ERROR, "Couldn't make DNS object.\n");
releaseAtom(query->name);
releaseAtom(message);
releaseObject(query->object);
cancelTimeEvent(query->timeout_handler);
free(query);
return -1;
}
if(dnsUseGethostbyname >= 1) {
releaseAtom(message);
do_log(L_WARN, "Falling back to using system resolver.\n");
really_do_gethostbyname(retainAtom(query->name), object);
} else {
releaseAtom(object->message);
object->message = message;
object->flags &= ~OBJECT_INPROGRESS;
releaseNotifyObject(object);
}
cancelTimeEvent(query->timeout_handler);
releaseAtom(query->name);
if(query->inet4) releaseAtom(query->inet4);
if(query->inet6) releaseAtom(query->inet6);
releaseObject(query->object);
free(query);
return 1;
}
int
do_gethostbyname(char *origname,
int count,
int (*handler)(int, GethostbynameRequestPtr),
void *data)
{
ObjectPtr object;
int n = strlen(origname);
AtomPtr name;
GethostbynameRequestRec request;
int done, rc;
memset(&request, 0, sizeof(request));
request.name = NULL;
request.addr = NULL;
request.error_message = NULL;
request.count = count;
request.handler = handler;
request.data = data;
if(n <= 0 || n > 131) {
if(n <= 0) {
request.error_message = internAtom("empty name");
do_log(L_ERROR, "Empty DNS name.\n");
done = handler(-EINVAL, &request);
} else {
request.error_message = internAtom("name too long");
do_log(L_ERROR, "DNS name too long.\n");
done = handler(-ENAMETOOLONG, &request);
}
assert(done);
releaseAtom(request.error_message);
return 1;
}
if(origname[n - 1] == '.')
n--;
name = internAtomLowerN(origname, n);
if(name == NULL) {
request.error_message = internAtom("couldn't allocate name");
do_log(L_ERROR, "Couldn't allocate DNS name.\n");
done = handler(-ENOMEM, &request);
assert(done);
releaseAtom(request.error_message);
return 1;
}
request.name = name;
request.addr = NULL;
request.error_message = NULL;
request.count = count;
request.object = NULL;
request.handler = handler;
request.data = data;
object = findObject(OBJECT_DNS, name->string, name->length);
if(object == NULL || objectMustRevalidate(object, NULL)) {
if(object) {
privatiseObject(object, 0);
releaseObject(object);
}
object = makeObject(OBJECT_DNS, name->string, name->length, 1, 0,
NULL, NULL);
if(object == NULL) {
request.error_message = internAtom("Couldn't allocate object");
do_log(L_ERROR, "Couldn't allocate DNS object.\n");
done = handler(-ENOMEM, &request);
assert(done);
releaseAtom(name);
releaseAtom(request.error_message);
return 1;
}
}
if((object->flags & (OBJECT_INITIAL | OBJECT_INPROGRESS)) ==
OBJECT_INITIAL) {
if(dnsUseGethostbyname >= 3)
rc = really_do_gethostbyname(name, object);
else
rc = really_do_dns(name, object);
if(rc < 0) {
assert(!(object->flags & (OBJECT_INITIAL | OBJECT_INPROGRESS)));
goto fail;
}
}
if(dnsUseGethostbyname >= 3)
assert(!(object->flags & OBJECT_INITIAL));
#ifndef NO_FANCY_RESOLVER
if(object->flags & OBJECT_INITIAL) {
ConditionHandlerPtr chandler;
assert(object->flags & OBJECT_INPROGRESS);
request.object = object;
chandler = conditionWait(&object->condition, dnsHandler,
sizeof(request), &request);
if(chandler == NULL)
goto fail;
return 1;
}
#endif
if(object->headers && object->headers->length > 0) {
if(object->headers->string[0] == DNS_A)
assert(((object->headers->length - 1) %
sizeof(HostAddressRec)) == 0);
else
assert(object->headers->string[0] == DNS_CNAME);
request.addr = retainAtom(object->headers);
} else if(object->message) {
request.error_message = retainAtom(object->message);
}
releaseObject(object);
if(request.addr && request.addr->length > 0)
done = handler(1, &request);
else
done = handler(-EDNS_HOST_NOT_FOUND, &request);
assert(done);
releaseAtom(request.addr); request.addr = NULL;
releaseAtom(request.name); request.name = NULL;
releaseAtom(request.error_message); request.error_message = NULL;
return 1;
fail:
releaseNotifyObject(object);
done = handler(-errno, &request);
assert(done);
releaseAtom(name);
return 1;
}
static int
dnsReplyHandler(int abort, FdEventHandlerPtr event)
{
int fd = event->fd;
char buf[2048];
int len, rc;
ObjectPtr object;
unsigned ttl = 0;
AtomPtr name, value, message = NULL;
int id;
int af;
DnsQueryPtr query;
AtomPtr cname = NULL;
if(abort) {
dnsSocketHandler = NULL;
rc = establishDnsSocket();
if(rc < 0) {
do_log(L_ERROR, "Couldn't reestablish DNS socket.\n");
/* At this point, we should abort all in-flight
DNS requests. Oh, well, they'll timeout anyway. */
}
return 1;
}
len = recv(fd, buf, 2048, 0);
if(len <= 0) {
if(errno == EINTR || errno == EAGAIN) return 0;
/* This is where we get ECONNREFUSED for an ICMP port unreachable */
do_log_error(L_ERROR, errno, "DNS: recv failed");
dnsGethostbynameFallback(-1, message);
return 0;
}
/* This could be a late reply to a query that timed out and was
resent, a reply to a query that timed out, or a reply to an
AAAA query when we already got a CNAME reply to the associated
A. We filter such replies straight away, without trying to
parse them. */
rc = dnsReplyId(buf, 0, len, &id);
if(rc < 0) {
do_log(L_WARN, "Short DNS reply.\n");
return 0;
}
if(!findQuery(id, NULL)) {
return 0;
}
rc = dnsDecodeReply(buf, 0, len, &id, &name, &value, &af, &ttl);
if(rc < 0) {
assert(value == NULL);
/* We only want to fallback on gethostbyname if we received a
reply that we could not understand. What about truncated
replies? */
if(rc < 0) {
do_log_error(L_WARN, -rc, "DNS");
if(dnsUseGethostbyname >= 2 ||
(dnsUseGethostbyname &&
(rc != -EDNS_HOST_NOT_FOUND && rc != -EDNS_NO_RECOVERY &&
rc != -EDNS_FORMAT))) {
dnsGethostbynameFallback(id, message);
return 0;
} else {
message = internAtom(pstrerror(-rc));
}
} else {
assert(name != NULL && id >= 0 && af >= 0);
}
}
query = findQuery(id, name);
if(query == NULL) {
/* Duplicate id ? */
releaseAtom(value);
releaseAtom(name);
return 0;
}
/* We're going to use the information in this reply. If it was an
error, construct an empty atom to distinguish it from information
we're still waiting for. */
if(value == NULL)
value = internAtom("");
again:
if(af == 4) {
if(query->inet4 == NULL) {
query->inet4 = value;
query->ttl4 = current_time.tv_sec + ttl;
} else
releaseAtom(value);
} else if(af == 6) {
if(query->inet6 == NULL) {
query->inet6 = value;
query->ttl6 = current_time.tv_sec + ttl;
} else
releaseAtom(value);
} else if(af == 0) {
/* Ignore errors in this case. */
if(query->inet4 && query->inet4->length == 0) {
releaseAtom(query->inet4);
query->inet4 = NULL;
}
if(query->inet6 && query->inet6->length == 0) {
releaseAtom(query->inet6);
query->inet6 = NULL;
}
if(query->inet4 || query->inet6) {
do_log(L_WARN, "Host %s has both %s and CNAME -- "
"ignoring CNAME.\n", scrub(query->name->string),
query->inet4 ? "A" : "AAAA");
releaseAtom(value);
value = internAtom("");
af = query->inet4 ? 4 : 6;
goto again;
} else {
cname = value;
}
}
if(rc >= 0 && !cname &&
((dnsQueryIPv6 < 3 && query->inet4 == NULL) ||
(dnsQueryIPv6 > 0 && query->inet6 == NULL)))
return 0;
/* This query is complete */
cancelTimeEvent(query->timeout_handler);
object = query->object;
if(object->flags & OBJECT_INITIAL) {
assert(!object->headers);
if(cname) {
assert(query->inet4 == NULL && query->inet6 == NULL);
object->headers = cname;
object->expires = current_time.tv_sec + ttl;
} else if((!query->inet4 || query->inet4->length == 0) &&
(!query->inet6 || query->inet6->length == 0)) {
releaseAtom(query->inet4);
releaseAtom(query->inet6);
object->expires = current_time.tv_sec + dnsNegativeTtl;
abortObject(object, 500, retainAtom(message));
} else if(!query->inet4 || query->inet4->length == 0) {
object->headers = query->inet6;
object->expires = query->ttl6;
releaseAtom(query->inet4);
} else if(!query->inet6 || query->inet6->length == 0) {
object->headers = query->inet4;
object->expires = query->ttl4;
releaseAtom(query->inet6);
} else {
/* need to merge results */
char buf[1024];
if(query->inet4->length + query->inet6->length > 1024) {
releaseAtom(query->inet4);
releaseAtom(query->inet6);
abortObject(object, 500, internAtom("DNS reply too long"));
} else {
if(dnsQueryIPv6 <= 1) {
memcpy(buf, query->inet4->string, query->inet4->length);
memcpy(buf + query->inet4->length,
query->inet6->string + 1, query->inet6->length - 1);
} else {
memcpy(buf, query->inet6->string, query->inet6->length);
memcpy(buf + query->inet6->length,
query->inet4->string + 1, query->inet4->length - 1);
}
object->headers =
internAtomN(buf,
query->inet4->length +
query->inet6->length - 1);
if(object->headers == NULL)
abortObject(object, 500,
internAtom("Couldn't allocate DNS atom"));
}
object->expires = MIN(query->ttl4, query->ttl6);
}
object->age = current_time.tv_sec;
object->flags &= ~(OBJECT_INITIAL | OBJECT_INPROGRESS);
} else {
do_log(L_WARN, "DNS object ex nihilo for %s.\n",
scrub(query->name->string));
}
removeQuery(query);
free(query);
releaseAtom(name);
releaseAtom(message);
releaseNotifyObject(object);
return 0;
}
