fluencelabs/musl
1
0
Fork 0
mirror of https://github.com/fluencelabs/musl synced 2025-06-26 21:22:11 +00:00
Code Issues Projects Releases Wiki Activity

de-duplicate dn_expand, fix return value and signature, clean up

Browse Source 
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.
This commit is contained in:
Rich Felker
2013-08-14 17:58:20 -04:00
parent cccc1844be
commit fcc522c923
3 changed files with 24 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
src/network/dn_expand.c
View File

@ -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);