@@ -80,6 +80,7 @@
#include <stdlib.h>
#include <string.h>
#include <shlib-compat.h>
+#include <scratch_buffer.h>
#if PACKETSZ > 65536
#define MAXPACKET PACKETSZ
@@ -114,11 +115,14 @@ __res_context_query (struct resolv_context *ctx, const char *name,
struct __res_state *statp = ctx->resp;
UHEADER *hp = (UHEADER *) answer;
UHEADER *hp2;
- int n, use_malloc = 0;
-
- size_t bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * QUERYSIZE;
- u_char *buf = alloca (bufsize);
- u_char *query1 = buf;
+ int n;
+
+ /* It requires 2 times QUERYSIZE for type == T_QUERY_A_AND_AAAA. */
+ struct scratch_buffer buf;
+ scratch_buffer_init (&buf);
+ _Static_assert (2 * QUERYSIZE <= sizeof (buf.__space.__c),
+ "scratch_buffer too small");
+ u_char *query1 = buf.data;
int nquery1 = -1;
u_char *query2 = NULL;
int nquery2 = 0;
@@ -129,37 +133,28 @@ __res_context_query (struct resolv_context *ctx, const char *name,
if (type == T_QUERY_A_AND_AAAA)
{
n = __res_context_mkquery (ctx, QUERY, name, class, T_A, NULL,
- query1, bufsize);
+ query1, buf.length);
if (n > 0)
{
if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
{
/* Use RESOLV_EDNS_BUFFER_SIZE because the receive
buffer can be reallocated. */
- n = __res_nopt (ctx, n, query1, bufsize,
+ n = __res_nopt (ctx, n, query1, buf.length,
RESOLV_EDNS_BUFFER_SIZE);
if (n < 0)
goto unspec_nomem;
}
nquery1 = n;
- /* Align the buffer. */
- int npad = ((nquery1 + __alignof__ (HEADER) - 1)
- & ~(__alignof__ (HEADER) - 1)) - nquery1;
- if (n > bufsize - npad)
- {
- n = -1;
- goto unspec_nomem;
- }
- int nused = n + npad;
- query2 = buf + nused;
+ query2 = buf.data + n;
n = __res_context_mkquery (ctx, QUERY, name, class, T_AAAA,
- NULL, query2, bufsize - nused);
+ NULL, query2, buf.length - n);
if (n > 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
/* Use RESOLV_EDNS_BUFFER_SIZE because the receive
buffer can be reallocated. */
- n = __res_nopt (ctx, n, query2, bufsize,
+ n = __res_nopt (ctx, n, query2, buf.length,
RESOLV_EDNS_BUFFER_SIZE);
nquery2 = n;
}
@@ -169,7 +164,7 @@ __res_context_query (struct resolv_context *ctx, const char *name,
else
{
n = __res_context_mkquery (ctx, QUERY, name, class, type, NULL,
- query1, bufsize);
+ query1, buf.length);
if (n > 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
@@ -181,27 +176,25 @@ __res_context_query (struct resolv_context *ctx, const char *name,
advertise = anslen;
else
advertise = RESOLV_EDNS_BUFFER_SIZE;
- n = __res_nopt (ctx, n, query1, bufsize, advertise);
+ n = __res_nopt (ctx, n, query1, buf.length, advertise);
}
nquery1 = n;
}
- if (__glibc_unlikely (n <= 0) && !use_malloc) {
+ if (__glibc_unlikely (n <= 0)) {
/* Retry just in case res_nmkquery failed because of too
short buffer. Shouldn't happen. */
- bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * MAXPACKET;
- buf = malloc (bufsize);
- if (buf != NULL) {
- query1 = buf;
- use_malloc = 1;
+ if (scratch_buffer_set_array_size (&buf,
+ T_QUERY_A_AND_AAAA ? 2 : 1,
+ MAXPACKET)) {
+ query1 = buf.data;
goto again;
}
}
if (__glibc_unlikely (n <= 0)) {
RES_SET_H_ERRNO(statp, NO_RECOVERY);
- if (use_malloc)
- free (buf);
+ scratch_buffer_free (&buf);
return (n);
}
@@ -224,8 +217,7 @@ __res_context_query (struct resolv_context *ctx, const char *name,
answerp2_malloced);
}
- if (use_malloc)
- free (buf);
+ scratch_buffer_free (&buf);
if (n < 0) {
RES_SET_H_ERRNO(statp, TRY_AGAIN);
return (n);
The bufsize on current Linux build is: size_t bufsize = (type == 439963904 ? 2 : 1) * (12 + 4 + 255 + 1); So with upper bound as 544 (2 * (12 + 4 + 255 + 1)). However, it might increase to 2 * PACKETSIZE later with malloc. The default scratch_buffer should fullfill the most usual allocation requirement. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Joe Simmons-Talbott <josimmon@redhat.com> --- resolv/res_query.c | 54 ++++++++++++++++++++-------------------------- 1 file changed, 23 insertions(+), 31 deletions(-)