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Rationalise DNS packet-buffer size calculations.

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This commit is contained in:
Simon Kelley
2014-01-08 12:10:28 +00:00
parent 871417d45d
commit 60b68069cf
4 changed files with 19 additions and 12 deletions
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7
src/dnsmasq.c
View File

@@ -90,7 +90,12 @@ int main (int argc, char **argv)
#endif
if (daemon->edns_pktsz < PACKETSZ)
daemon->edns_pktsz = option_bool(OPT_DNSSEC_VALID) ? EDNS_PKTSZ : PACKETSZ;
daemon->edns_pktsz = PACKETSZ;
#ifdef HAVE_DNSSEC
/* Enforce min packet big enough for DNSSEC */
if (option_bool(OPT_DNSSEC_VALID) && daemon->edns_pktsz < EDNS_PKTSZ)
daemon->edns_pktsz = EDNS_PKTSZ;
#endif
daemon->packet_buff_sz = daemon->edns_pktsz > DNSMASQ_PACKETSZ ?
daemon->edns_pktsz : DNSMASQ_PACKETSZ;
daemon->packet = safe_malloc(daemon->packet_buff_sz);

2
src/dnsmasq.h
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@@ -1048,7 +1048,7 @@ int in_zone(struct auth_zone *zone, char *name, char **cut);
#endif
/* dnssec.c */
size_t dnssec_generate_query(struct dns_header *header, char *name, int class, int type, union mysockaddr *addr);
size_t dnssec_generate_query(struct dns_header *header, char *end, char *name, int class, int type, union mysockaddr *addr);
int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t n, char *name, char *keyname, int class);
int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class);
int validate_rrset(time_t now, struct dns_header *header, size_t plen, int class,

4
src/dnssec.c
View File

@@ -479,7 +479,7 @@ static int digestalg_add_rdata(int sigtype, struct dns_header *header, size_t pk
return 1;
}
size_t dnssec_generate_query(struct dns_header *header, char *name, int class, int type, union mysockaddr *addr)
size_t dnssec_generate_query(struct dns_header *header, char *end, char *name, int class, int type, union mysockaddr *addr)
{
unsigned char *p;
char types[20];
@@ -511,7 +511,7 @@ size_t dnssec_generate_query(struct dns_header *header, char *name, int class, i
PUTSHORT(type, p);
PUTSHORT(class, p);
return add_do_bit(header, p - (unsigned char *)header, ((char *) header) + PACKETSZ);
return add_do_bit(header, p - (unsigned char *)header, end);
}
/* The DNS packet is expected to contain the answer to a DNSKEY query.

18
src/forward.c
View File

@@ -330,11 +330,11 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
int forwarded = 0;
if (option_bool(OPT_ADD_MAC))
plen = add_mac(header, plen, ((char *) header) + PACKETSZ, &forward->source);
plen = add_mac(header, plen, ((char *) header) + daemon->packet_buff_sz, &forward->source);
if (option_bool(OPT_CLIENT_SUBNET))
{
size_t new = add_source_addr(header, plen, ((char *) header) + PACKETSZ, &forward->source);
size_t new = add_source_addr(header, plen, ((char *) header) + daemon->packet_buff_sz, &forward->source);
if (new != plen)
{
plen = new;
@@ -345,7 +345,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID))
{
plen = add_do_bit(header, plen, ((char *) header) + PACKETSZ);
plen = add_do_bit(header, plen, ((char *) header) + daemon->packet_buff_sz);
header->hb4 |= HB4_CD;
}
#endif
@@ -585,7 +585,7 @@ void reply_query(int fd, int family, time_t now)
union mysockaddr serveraddr;
struct frec *forward;
socklen_t addrlen = sizeof(serveraddr);
ssize_t n = recvfrom(fd, daemon->packet, daemon->edns_pktsz, 0, &serveraddr.sa, &addrlen);
ssize_t n = recvfrom(fd, daemon->packet, daemon->packet_buff_sz, 0, &serveraddr.sa, &addrlen);
size_t nn;
struct server *server;
@@ -732,12 +732,14 @@ void reply_query(int fd, int family, time_t now)
if (status == STAT_NEED_KEY)
{
new->flags |= FREC_DNSKEY_QUERY;
nn = dnssec_generate_query(header, daemon->keyname, forward->class, T_DNSKEY, &server->addr);
nn = dnssec_generate_query(header, ((char *) header) + daemon->packet_buff_sz,
daemon->keyname, forward->class, T_DNSKEY, &server->addr);
}
else if (status == STAT_NEED_DS)
{
new->flags |= FREC_DS_QUERY;
nn = dnssec_generate_query(header, daemon->keyname, forward->class, T_DS, &server->addr);
nn = dnssec_generate_query(header,((char *) header) + daemon->packet_buff_sz,
daemon->keyname, forward->class, T_DS, &server->addr);
}
new->crc = questions_crc(header, nn, daemon->namebuff);
new->new_id = get_id(new->crc);
@@ -1064,7 +1066,7 @@ void receive_query(struct listener *listen, time_t now)
#ifdef HAVE_AUTH
if (auth_dns)
{
m = answer_auth(header, ((char *) header) + PACKETSZ, (size_t)n, now, &source_addr, local_auth);
m = answer_auth(header, ((char *) header) + daemon->packet_buff_sz, (size_t)n, now, &source_addr, local_auth);
if (m >= 1)
{
send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND),
@@ -1075,7 +1077,7 @@ void receive_query(struct listener *listen, time_t now)
else
#endif
{
m = answer_request(header, ((char *) header) + PACKETSZ, (size_t)n,
m = answer_request(header, ((char *) header) + daemon->packet_buff_sz, (size_t)n,
dst_addr_4, netmask, now);
if (m >= 1)