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Handle UDP packet loss when fragmentation of large packets is broken.

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This commit is contained in:
Simon Kelley
2015-05-08 16:25:38 +01:00
parent 64bcff1c7c
commit a77cec8d58
8 changed files with 66 additions and 35 deletions
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37
src/forward.c
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@@ -253,6 +253,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
void *hash = &crc;
#endif
unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
unsigned char *pheader;
(void)do_bit;
@@ -261,19 +262,32 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
forward = NULL;
else if (forward || (hash && (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash))))
{
/* If we didn't get an answer advertising a maximal packet in EDNS,
fall back to 1280, which should work everywhere on IPv6.
If that generates an answer, it will become the new default
for this server */
forward->flags |= FREC_TEST_PKTSZ;
#ifdef HAVE_DNSSEC
/* If we've already got an answer to this query, but we're awaiting keys for validation,
there's no point retrying the query, retry the key query instead...... */
if (forward->blocking_query)
{
int fd;
forward->flags &= ~FREC_TEST_PKTSZ;
while (forward->blocking_query)
forward = forward->blocking_query;
forward->flags |= FREC_TEST_PKTSZ;
blockdata_retrieve(forward->stash, forward->stash_len, (void *)header);
plen = forward->stash_len;
if (find_pseudoheader(header, plen, NULL, &pheader, NULL))
PUTSHORT((forward->flags & FREC_TEST_PKTSZ) ? SAFE_PKTSZ : forward->sentto->edns_pktsz, pheader);
if (forward->sentto->addr.sa.sa_family == AF_INET)
log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, "retry", (struct all_addr *)&forward->sentto->addr.in.sin_addr, "dnssec");
#ifdef HAVE_IPV6
@@ -417,7 +431,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
plen = new_plen;
}
#endif
while (1)
{
/* only send to servers dealing with our domain.
@@ -464,6 +478,9 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
}
#endif
}
if (find_pseudoheader(header, plen, NULL, &pheader, NULL))
PUTSHORT((forward->flags & FREC_TEST_PKTSZ) ? SAFE_PKTSZ : start->edns_pktsz, pheader);
if (retry_send(sendto(fd, (char *)header, plen, 0,
&start->addr.sa,
@@ -760,7 +777,6 @@ void reply_query(int fd, int family, time_t now)
}
server = forward->sentto;
if ((forward->sentto->flags & SERV_TYPE) == 0)
{
if (RCODE(header) == REFUSED)
@@ -781,7 +797,12 @@ void reply_query(int fd, int family, time_t now)
if (!option_bool(OPT_ALL_SERVERS))
daemon->last_server = server;
}
/* We tried resending to this server with a smaller maximum size and got an answer.
Make that permanent. */
if (server && (forward->flags & FREC_TEST_PKTSZ))
server->edns_pktsz = SAFE_PKTSZ;
/* If the answer is an error, keep the forward record in place in case
we get a good reply from another server. Kill it when we've
had replies from all to avoid filling the forwarding table when
@@ -890,7 +911,7 @@ void reply_query(int fd, int family, time_t now)
{
new->flags |= FREC_DNSKEY_QUERY;
nn = dnssec_generate_query(header, ((char *) header) + daemon->packet_buff_sz,
daemon->keyname, forward->class, T_DNSKEY, &server->addr);
daemon->keyname, forward->class, T_DNSKEY, &server->addr, server->edns_pktsz);
}
else
{
@@ -899,7 +920,7 @@ void reply_query(int fd, int family, time_t now)
else
new->flags |= FREC_DS_QUERY;
nn = dnssec_generate_query(header,((char *) header) + daemon->packet_buff_sz,
daemon->keyname, forward->class, T_DS, &server->addr);
daemon->keyname, forward->class, T_DS, &server->addr, server->edns_pktsz);
}
if ((hash = hash_questions(header, nn, daemon->namebuff)))
memcpy(new->hash, hash, HASH_SIZE);
@@ -1526,7 +1547,7 @@ static int tcp_check_for_unsigned_zone(time_t now, struct dns_header *header, s
/* Can't find it in the cache, have to send a query */
m = dnssec_generate_query(header, ((char *) header) + 65536, name_start, class, T_DS, &server->addr);
m = dnssec_generate_query(header, ((char *) header) + 65536, name_start, class, T_DS, &server->addr, server->edns_pktsz);
*length = htons(m);
@@ -1638,7 +1659,7 @@ static int tcp_key_recurse(time_t now, int status, struct dns_header *header, si
another_tcp_key:
m = dnssec_generate_query(new_header, ((char *) new_header) + 65536, keyname, class,
new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS, &server->addr);
new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS, &server->addr, server->edns_pktsz);
*length = htons(m);