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authorRich Felker <dalias@aerifal.cx>2013-08-14 17:58:20 -0400
committerRich Felker <dalias@aerifal.cx>2013-08-14 17:58:20 -0400
commitfcc522c92335783293ac19df318415cd97fbf66b (patch)
tree35de93be8123cb7cd075994087d132e3c8bbb906
parentcccc1844be95549e5b6c91ffc1f2c2ba3d3aab16 (diff)
downloadmusl-fcc522c92335783293ac19df318415cd97fbf66b.tar.gz
de-duplicate dn_expand, fix return value and signature, clean up
the duplicate code in dn_expand and its incorrect return values are both results of the history of the code: the version in __dns.c was originally written with no awareness of the legacy resolver API, and was later copy-and-paste duplicated to provide the legacy API. this commit is the first of a series that will restructure the internal dns code to share as much code as possible with the legacy resolver API functions. I have also removed the loop detection logic, since the output buffer length limit naturally prevents loops. in order to avoid long runtime when encountering a loop if the caller provided a ridiculously long buffer, the caller-provided length is clamped at the maximum dns name length.
-rw-r--r--include/resolv.h2
-rw-r--r--src/network/__dns.c30
-rw-r--r--src/network/dn_expand.c41
3 files changed, 24 insertions, 49 deletions
diff --git a/include/resolv.h b/include/resolv.h
index cdedd274..259e4bc1 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -134,7 +134,7 @@ int res_search(const char *, int, int, unsigned char *, int);
int res_mkquery(int, const char *, int, int, char *, int, struct rrec *, char *, int);
int res_send(const char *, int, char *, int);
int dn_comp(unsigned char *, unsigned char *, int, unsigned char **, unsigned char *, unsigned char **);
-int dn_expand(unsigned char *, unsigned char *, unsigned char *, unsigned char *, int);
+int dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
int dn_skipname(const unsigned char *, const unsigned char *);
#ifdef __cplusplus
diff --git a/src/network/__dns.c b/src/network/__dns.c
index 372a5871..8f3c6370 100644
--- a/src/network/__dns.c
+++ b/src/network/__dns.c
@@ -195,32 +195,7 @@ int __dns_query(unsigned char *r, const void *a, int family, int ptr)
return __dns_doqueries(r, a, rr, rrcnt);
}
-
-#define BITOP(a,b,op) \
- ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
-
-static int decname(char *s, const unsigned char *b, const unsigned char *p)
-{
- /* Remember jump destinations to detect loops and abort */
- size_t seen[PACKET_MAX/8/sizeof(size_t)] = { 0 };
- char *sz = s + HOST_NAME_MAX;
- const unsigned char *pz = b+512;
- for (;;) {
- if (p>=pz) return -1;
- else if (*p&0xc0) {
- int j = (p[0]&1) | p[1];
- if (BITOP(seen, j, &)) return -1;
- BITOP(seen, j, |=);
- p = b + j;
- } else if (*p) {
- if (p+*p+1>=pz || s+*p>=sz) return -1;
- memcpy(s, p+1, *p);
- s += *p+1;
- p += *p+1;
- s[-1] = *p ? '.' : 0;
- } else return 0;
- }
-}
+int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
int __dns_get_rr(void *dest, size_t stride, size_t maxlen, size_t limit, const unsigned char *r, int rr, int dec)
{
@@ -249,7 +224,8 @@ int __dns_get_rr(void *dest, size_t stride, size_t maxlen, size_t limit, const u
len = p[8]*256 + p[9];
if (p+len > r+512) return -1;
if (p[1]==rr && len <= maxlen) {
- if (dec && decname(tmp, r, p+10)<0) return -1;
+ if (dec && __dn_expand(r, r+512, p+10, tmp, sizeof tmp)<0)
+ return -1;
if (dest && limit) {
if (dec) strcpy(dest, tmp);
else memcpy(dest, p+10, len);
diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
index 01b449bb..72a80e82 100644
--- a/src/network/dn_expand.c
+++ b/src/network/dn_expand.c
@@ -1,28 +1,27 @@
#include <resolv.h>
-#include <string.h>
+#include "libc.h"
-#define BITOP(a,b,op) \
- ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
-
-int dn_expand(unsigned char *b, unsigned char *pz, unsigned char *p, unsigned char *s, int outlen)
+int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
{
- /* Remember jump destinations to detect loops and abort */
- size_t seen[512/8/sizeof(size_t)] = { 0 };
- unsigned char *sz = s + outlen;
- if (pz-b > 512) return -1;
+ const unsigned char *p = src;
+ int len = -1, j;
+ if (space > 256) space = 256;
+ if (p==end) return -1;
for (;;) {
- if (p>=pz) return -1;
- else if (*p&0xc0) {
- int j = (p[0]&1) | p[1];
- if (BITOP(seen, j, &)) return -1;
- BITOP(seen, j, |=);
- p = b + j;
+ if (*p & 0xc0) {
+ if (p+1==end) return -1;
+ j = (p[0]&1) | p[1];
+ if (len < 0) len = p+2-src;
+ if (j >= end-base) return -1;
+ p = base+j;
} else if (*p) {
- if (p+*p+1>=pz || s+*p>=sz) return -1;
- memcpy(s, p+1, *p);
- s += *p+1;
- p += *p+1;
- s[-1] = *p ? '.' : 0;
- } else return 0;
+ j = *p+1;
+ if (len < 0) len = p+1-src;
+ if (j>=end-p || j>space) return -1;
+ while (--j) *dest++ = *p++;
+ *dest++ = *++p ? '.' : 0;
+ } else return len;
}
}
+
+weak_alias(__dn_expand, dn_expand);