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Diffstat (limited to 'ares_parse_aaaa_reply.c')
-rw-r--r--ares_parse_aaaa_reply.c128
1 files changed, 96 insertions, 32 deletions
diff --git a/ares_parse_aaaa_reply.c b/ares_parse_aaaa_reply.c
index 535d40e..3b578f1 100644
--- a/ares_parse_aaaa_reply.c
+++ b/ares_parse_aaaa_reply.c
@@ -40,19 +40,26 @@
#include "ares_private.h"
int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
- struct hostent **host)
+ struct hostent **host, struct addr6ttl *addrttls,
+ int *naddrttls)
{
unsigned int qdcount, ancount;
- int status, i, rr_type, rr_class, rr_len, naddrs;
+ int status, i, rr_type, rr_class, rr_len, rr_ttl, naddrs;
+ int cname_ttl = INT_MAX; /* the TTL imposed by the CNAME chain */
int naliases;
long len;
const unsigned char *aptr;
char *hostname, *rr_name, *rr_data, **aliases;
struct in6_addr *addrs;
struct hostent *hostent;
+ const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0;
/* Set *host to NULL for all failure cases. */
- *host = NULL;
+ if (host)
+ *host = NULL;
+ /* Same with *naddrttls. */
+ if (naddrttls)
+ *naddrttls = 0;
/* Give up if abuf doesn't have room for a header. */
if (alen < HFIXEDSZ)
@@ -77,18 +84,26 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
aptr += len + QFIXEDSZ;
/* Allocate addresses and aliases; ancount gives an upper bound for both. */
- addrs = malloc(ancount * sizeof(struct in6_addr));
- if (!addrs)
+ if (host)
{
- free(hostname);
- return ARES_ENOMEM;
+ addrs = malloc(ancount * sizeof(struct in6_addr));
+ if (!addrs)
+ {
+ free(hostname);
+ return ARES_ENOMEM;
+ }
+ aliases = malloc((ancount + 1) * sizeof(char *));
+ if (!aliases)
+ {
+ free(hostname);
+ free(addrs);
+ return ARES_ENOMEM;
+ }
}
- aliases = malloc((ancount + 1) * sizeof(char *));
- if (!aliases)
+ else
{
- free(hostname);
- free(addrs);
- return ARES_ENOMEM;
+ addrs = NULL;
+ aliases = NULL;
}
naddrs = 0;
naliases = 0;
@@ -109,13 +124,33 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
rr_type = DNS_RR_TYPE(aptr);
rr_class = DNS_RR_CLASS(aptr);
rr_len = DNS_RR_LEN(aptr);
+ rr_ttl = DNS_RR_TTL(aptr);
aptr += RRFIXEDSZ;
if (rr_class == C_IN && rr_type == T_AAAA
&& rr_len == sizeof(struct in6_addr)
&& strcasecmp(rr_name, hostname) == 0)
{
- memcpy(&addrs[naddrs], aptr, sizeof(struct in6_addr));
+ if (addrs)
+ {
+ if (aptr + sizeof(struct in6_addr) > abuf + alen)
+ {
+ status = ARES_EBADRESP;
+ break;
+ }
+ memcpy(&addrs[naddrs], aptr, sizeof(struct in6_addr));
+ }
+ if (naddrs < max_addr_ttls)
+ {
+ struct addr6ttl * const at = &addrttls[naddrs];
+ if (aptr + sizeof(struct in6_addr) > abuf + alen)
+ {
+ status = ARES_EBADRESP;
+ break;
+ }
+ memcpy(&at->ip6addr, aptr, sizeof(struct in6_addr));
+ at->ttl = rr_ttl;
+ }
naddrs++;
status = ARES_SUCCESS;
}
@@ -123,7 +158,10 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
if (rr_class == C_IN && rr_type == T_CNAME)
{
/* Record the RR name as an alias. */
- aliases[naliases] = rr_name;
+ if (aliases)
+ aliases[naliases] = rr_name;
+ else
+ free(rr_name);
naliases++;
/* Decode the RR data and replace the hostname with it. */
@@ -132,6 +170,10 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
break;
free(hostname);
hostname = rr_data;
+
+ /* Take the min of the TTLs we see in the CNAME chain. */
+ if (cname_ttl > rr_ttl)
+ cname_ttl = rr_ttl;
}
else
free(rr_name);
@@ -148,28 +190,50 @@ int ares_parse_aaaa_reply(const unsigned char *abuf, int alen,
status = ARES_ENODATA;
if (status == ARES_SUCCESS)
{
- /* We got our answer. Allocate memory to build the host entry. */
- aliases[naliases] = NULL;
- hostent = malloc(sizeof(struct hostent));
- if (hostent)
+ /* We got our answer. */
+ if (naddrttls)
{
- hostent->h_addr_list = malloc((naddrs + 1) * sizeof(char *));
- if (hostent->h_addr_list)
+ const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls;
+ for (i = 0; i < n; i++)
{
- /* Fill in the hostent and return successfully. */
- hostent->h_name = hostname;
- hostent->h_aliases = aliases;
- hostent->h_addrtype = AF_INET6;
- hostent->h_length = sizeof(struct in6_addr);
- for (i = 0; i < naddrs; i++)
- hostent->h_addr_list[i] = (char *) &addrs[i];
- hostent->h_addr_list[naddrs] = NULL;
- *host = hostent;
- return ARES_SUCCESS;
+ /* Ensure that each A TTL is no larger than the CNAME TTL. */
+ if (addrttls[i].ttl > cname_ttl)
+ addrttls[i].ttl = cname_ttl;
}
- free(hostent);
+ *naddrttls = n;
}
- status = ARES_ENOMEM;
+ if (aliases)
+ aliases[naliases] = NULL;
+ if (host)
+ {
+ /* Allocate memory to build the host entry. */
+ hostent = malloc(sizeof(struct hostent));
+ if (hostent)
+ {
+ hostent->h_addr_list = malloc((naddrs + 1) * sizeof(char *));
+ if (hostent->h_addr_list)
+ {
+ /* Fill in the hostent and return successfully. */
+ hostent->h_name = hostname;
+ hostent->h_aliases = aliases;
+ hostent->h_addrtype = AF_INET6;
+ hostent->h_length = sizeof(struct in6_addr);
+ for (i = 0; i < naddrs; i++)
+ hostent->h_addr_list[i] = (char *) &addrs[i];
+ hostent->h_addr_list[naddrs] = NULL;
+ *host = hostent;
+ return ARES_SUCCESS;
+ }
+ free(hostent);
+ }
+ status = ARES_ENOMEM;
+ }
+ }
+ if (aliases)
+ {
+ for (i = 0; i < naliases; i++)
+ free(aliases[i]);
+ free(aliases);
}
for (i = 0; i < naliases; i++)
free(aliases[i]);