static int
lingeringCloseHandler(int status, FdEventHandlerPtr event)
{
LingeringClosePtr l = *(LingeringClosePtr*)event->data;
char buf[17];
int rc;
assert(l->handler == event);
l->handler = NULL;
if(status && status != -EDOGRACEFUL)
goto done;
rc = READ(l->fd, &buf, 17);
if(rc == 0 || (rc < 0 && errno != EAGAIN && errno != EINTR))
goto done;
/* The client is still sending data. Ignore it in order to let
TCP's flow control do its work. The timeout will close the
connection. */
return 1;
done:
if(l->timeout) {
cancelTimeEvent(l->timeout);
l->timeout = NULL;
}
CLOSE(l->fd);
free(l);
return 1;
}
static int lingeringCloseHandler(int status, FdEventHandlerPtr event)
{
LingeringClosePtr l = *(LingeringClosePtr *) event->data;
char buf[17];
int rc;
assert(l->handler == event);
l->handler = NULL;
if (status && status != -EDOGRACEFUL)
goto done;
rc = READ(l->fd, &buf, 17);
if (rc == 0 || (rc < 0 && errno != EAGAIN && errno != EINTR))
goto done;
return 1;
done:
if (l->timeout) {
cancelTimeEvent(l->timeout);
l->timeout = NULL;
}
CLOSE(l->fd);
free(l);
return 1;
}
static int
really_do_dns(AtomPtr name, ObjectPtr object)
{
int rc;
DnsQueryPtr query;
AtomPtr message = NULL;
int id;
AtomPtr a = NULL;
if(a == NULL) {
if(name == atomLocalhost || name == atomLocalhostDot) {
char s[1 + sizeof(HostAddressRec)];
memset(s, 0, sizeof(s));
s[0] = DNS_A;
s[1] = 4;
s[2] = 127;
s[3] = 0;
s[4] = 0;
s[5] = 1;
a = internAtomN(s, 1 + sizeof(HostAddressRec));
if(a == NULL) {
abortObject(object, 501,
internAtom("Couldn't allocate address"));
notifyObject(object);
errno = ENOMEM;
return -1;
}
}
}
if(a == NULL) {
struct in_addr ina;
rc = inet_aton(name->string, &ina);
if(rc == 1) {
char s[1 + sizeof(HostAddressRec)];
memset(s, 0, sizeof(s));
s[0] = DNS_A;
s[1] = 4;
memcpy(s + 2, &ina, 4);
a = internAtomN(s, 1 + sizeof(HostAddressRec));
if(a == NULL) {
abortObject(object, 501,
internAtom("Couldn't allocate address"));
notifyObject(object);
errno = ENOMEM;
return -1;
}
}
}
#ifdef HAVE_IPv6
if(a == NULL)
a = rfc2732(name);
#endif
if(a) {
object->headers = a;
object->age = current_time.tv_sec;
object->expires = current_time.tv_sec + 240;
object->flags &= ~(OBJECT_INITIAL | OBJECT_INPROGRESS);
notifyObject(object);
return 0;
}
rc = establishDnsSocket();
if(rc < 0) {
do_log_error(L_ERROR, -rc, "Couldn't establish DNS socket.\n");
message = internAtomError(-rc, "Couldn't establish DNS socket");
goto fallback;
}
/* The id is used to speed up detecting replies to queries that
are no longer current -- see dnsReplyHandler. */
id = (idSeed++) & 0xFFFF;
query = malloc(sizeof(DnsQueryRec));
if(query == NULL) {
do_log(L_ERROR, "Couldn't allocate DNS query.\n");
message = internAtom("Couldn't allocate DNS query");
goto fallback;
}
query->id = id;
query->inet4 = NULL;
query->inet6 = NULL;
query->name = name;
query->time = current_time.tv_sec;
query->object = retainObject(object);
query->timeout = 4;
query->timeout_handler = NULL;
query->next = NULL;
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");
message = internAtom("Couldn't schedule DNS timeout handler");
goto free_fallback;
}
insertQuery(query);
object->flags |= OBJECT_INPROGRESS;
rc = sendQuery(query);
if(rc < 0) {
if(rc != -EWOULDBLOCK && rc != -EAGAIN && rc != -ENOBUFS) {
object->flags &= ~OBJECT_INPROGRESS;
message = internAtomError(-rc, "Couldn't send DNS query");
goto remove_fallback;
}
/* else let it timeout */
}
releaseAtom(message);
return 1;
remove_fallback:
removeQuery(query);
free_fallback:
releaseObject(query->object);
cancelTimeEvent(query->timeout_handler);
free(query);
fallback:
if(dnsUseGethostbyname >= 1) {
releaseAtom(message);
do_log(L_WARN, "Falling back on gethostbyname.\n");
return really_do_gethostbyname(name, object);
} else {
abortObject(object, 501, message);
notifyObject(object);
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;
}
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;
}
