*
* Loosely based on the isc-dhcpd implementation by dhankins@isc.org
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
-
-#if ENABLE_FEATURE_RFC3397
-
-#include "common.h"
-#include "options.h"
+#ifdef DNS_COMPR_TESTING
+# define FAST_FUNC /* nothing */
+# define xmalloc malloc
+# include <stdlib.h>
+# include <stdint.h>
+# include <string.h>
+# include <stdio.h>
+#else
+# include "common.h"
+#endif
#define NS_MAXDNAME 1025 /* max domain name length */
#define NS_MAXCDNAME 255 /* max compressed domain name length */
#define NS_CMPRSFLGS 0xc0 /* name compression pointer flag */
-/* expand a RFC1035-compressed list of domain names "cstr", of length "clen";
+/* Expand a RFC1035-compressed list of domain names "cstr", of length "clen";
* returns a newly allocated string containing the space-separated domains,
* prefixed with the contents of string pre, or NULL if an error occurs.
*/
-char *dname_dec(const uint8_t *cstr, int clen, const char *pre)
+char* FAST_FUNC dname_dec(const uint8_t *cstr, int clen, const char *pre)
{
- const uint8_t *c;
- int crtpos, retpos, depth, plen = 0, len = 0;
+ char *ret = ret; /* for compiler */
char *dst = NULL;
- if (!cstr)
- return NULL;
-
- if (pre)
- plen = strlen(pre);
-
/* We make two passes over the cstr string. First, we compute
* how long the resulting string would be. Then we allocate a
* new buffer of the required length, and fill it in with the
* having to deal with requiring callers to supply their own
* buffer, then having to check if it's sufficiently large, etc.
*/
-
- while (!dst) {
-
- if (len > 0) { /* second pass? allocate dst buffer and copy pre */
- dst = xmalloc(len + plen);
- memcpy(dst, pre, plen);
- }
+ while (1) {
+ /* note: "return NULL" below are leak-safe since
+ * dst isn't yet allocated */
+ const uint8_t *c;
+ unsigned crtpos, retpos, depth, len;
crtpos = retpos = depth = len = 0;
-
while (crtpos < clen) {
c = cstr + crtpos;
- if ((*c & NS_CMPRSFLGS) != 0) { /* pointer */
- if (crtpos + 2 > clen) /* no offset to jump to? abort */
+ if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
+ /* pointer */
+ if (crtpos + 2 > clen) /* no offset to jump to? abort */
return NULL;
- if (retpos == 0) /* toplevel? save return spot */
+ if (retpos == 0) /* toplevel? save return spot */
retpos = crtpos + 2;
depth++;
- crtpos = ((*c & 0x3f) << 8) | (*(c + 1) & 0xff); /* jump */
- } else if (*c) { /* label */
- if (crtpos + *c + 1 > clen) /* label too long? abort */
+ crtpos = ((c[0] & 0x3f) << 8) | c[1]; /* jump */
+ } else if (*c) {
+ /* label */
+ if (crtpos + *c + 1 > clen) /* label too long? abort */
return NULL;
if (dst)
- memcpy(dst + plen + len, c + 1, *c);
+ memcpy(dst + len, c + 1, *c);
len += *c + 1;
crtpos += *c + 1;
if (dst)
- *(dst + plen + len - 1) = '.';
- } else { /* null: end of current domain name */
- if (retpos == 0) { /* toplevel? keep going */
+ dst[len - 1] = '.';
+ } else {
+ /* NUL: end of current domain name */
+ if (retpos == 0) {
+ /* toplevel? keep going */
crtpos++;
- } else { /* return to toplevel saved spot */
+ } else {
+ /* return to toplevel saved spot */
crtpos = retpos;
retpos = depth = 0;
}
if (dst)
- *(dst + plen + len - 1) = ' ';
+ dst[len - 1] = ' ';
}
- if (depth > NS_MAXDNSRCH || /* too many jumps? abort, it's a loop */
- len > NS_MAXDNAME * NS_MAXDNSRCH) /* result too long? abort */
+ if (depth > NS_MAXDNSRCH /* too many jumps? abort, it's a loop */
+ || len > NS_MAXDNAME * NS_MAXDNSRCH /* result too long? abort */
+ ) {
return NULL;
+ }
}
- if (!len) /* expanded string has 0 length? abort */
+ if (!len) /* expanded string has 0 length? abort */
return NULL;
- if (dst)
- *(dst + plen + len - 1) = '\0';
+ if (!dst) { /* first pass? */
+ /* allocate dst buffer and copy pre */
+ unsigned plen = strlen(pre);
+ ret = dst = xmalloc(plen + len);
+ memcpy(dst, pre, plen);
+ dst += plen;
+ } else {
+ dst[len - 1] = '\0';
+ break;
+ }
}
- return dst;
+ return ret;
}
/* Convert a domain name (src) from human-readable "foo.blah.com" format into
*/
static uint8_t *convert_dname(const char *src)
{
- uint8_t c, *res, *lp, *rp;
+ uint8_t c, *res, *lenptr, *dst;
int len;
res = xmalloc(strlen(src) + 2);
- rp = lp = res;
- rp++;
+ dst = lenptr = res;
+ dst++;
for (;;) {
c = (uint8_t)*src++;
- if (c == '.' || c == '\0') { /* end of label */
- len = rp - lp - 1;
+ if (c == '.' || c == '\0') { /* end of label */
+ len = dst - lenptr - 1;
/* label too long, too short, or two '.'s in a row? abort */
if (len > NS_MAXLABEL || len == 0 || (c == '.' && *src == '.')) {
free(res);
return NULL;
}
- *lp = len;
- lp = rp++;
- if (c == '\0' || *src == '\0') /* end of dname */
+ *lenptr = len;
+ if (c == '\0' || *src == '\0') /* "" or ".": end of src */
break;
- } else {
- if (c >= 0x41 && c <= 0x5A) /* uppercase? convert to lower */
- c += 0x20;
- *rp++ = c;
+ lenptr = dst++;
+ continue;
}
+ if (c >= 'A' && c <= 'Z') /* uppercase? convert to lower */
+ c += ('a' - 'A');
+ *dst++ = c;
}
- *lp = 0;
- if (rp - res > NS_MAXCDNAME) { /* dname too long? abort */
+ if (dst - res >= NS_MAXCDNAME) { /* dname too long? abort */
free(res);
return NULL;
}
+
+ *dst = 0;
return res;
}
-/* returns the offset within cstr at which dname can be found, or -1
- */
+/* Returns the offset within cstr at which dname can be found, or -1 */
static int find_offset(const uint8_t *cstr, int clen, const uint8_t *dname)
{
const uint8_t *c, *d;
- int off, inc;
+ int off;
/* find all labels in cstr */
off = 0;
while (off < clen) {
c = cstr + off;
- if ((*c & NS_CMPRSFLGS) != 0) { /* pointer, skip */
+ if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS) { /* pointer, skip */
off += 2;
- } else if (*c) { /* label, try matching dname */
- inc = *c + 1;
+ continue;
+ }
+ if (*c) { /* label, try matching dname */
d = dname;
- while (*c == *d && memcmp(c + 1, d + 1, *c) == 0) {
- if (*c == 0) /* match, return offset */
+ while (1) {
+ unsigned len1 = *c + 1;
+ if (memcmp(c, d, len1) != 0)
+ break;
+ if (len1 == 1) /* at terminating NUL - match, return offset */
return off;
- d += *c + 1;
- c += *c + 1;
- if ((*c & NS_CMPRSFLGS) != 0) /* pointer, jump */
- c = cstr + (((*c & 0x3f) << 8) | (*(c + 1) & 0xff));
+ d += len1;
+ c += len1;
+ if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS) /* pointer, jump */
+ c = cstr + (((c[0] & 0x3f) << 8) | c[1]);
}
- off += inc;
- } else { /* null, skip */
- off++;
+ off += cstr[off] + 1;
+ continue;
}
+ /* NUL, skip */
+ off++;
}
return -1;
}
-/* computes string to be appended to cstr so that src would be added to
+/* Computes string to be appended to cstr so that src would be added to
* the compression (best case, it's a 2-byte pointer to some offset within
- * cstr; worst case, it's all of src, converted to rfc3011 format).
+ * cstr; worst case, it's all of src, converted to <4>host<3>com<0> format).
* The computed string is returned directly; its length is returned via retlen;
* NULL and 0, respectively, are returned if an error occurs.
*/
-uint8_t *dname_enc(const uint8_t *cstr, int clen, const char *src, int *retlen)
+uint8_t* FAST_FUNC dname_enc(const uint8_t *cstr, int clen, const char *src, int *retlen)
{
uint8_t *d, *dname;
int off;
return NULL;
}
- for (d = dname; *d != 0; d += *d + 1) {
- off = find_offset(cstr, clen, d);
- if (off >= 0) { /* found a match, add pointer and terminate string */
- *d++ = NS_CMPRSFLGS;
- *d = off;
- break;
+ d = dname;
+ while (*d) {
+ if (cstr) {
+ off = find_offset(cstr, clen, d);
+ if (off >= 0) { /* found a match, add pointer and return */
+ *d++ = NS_CMPRSFLGS | (off >> 8);
+ *d = off;
+ break;
+ }
}
+ d += *d + 1;
}
*retlen = d - dname + 1;
return dname;
-}
+}
-#endif /* ENABLE_FEATURE_RFC3397 */
+#ifdef DNS_COMPR_TESTING
+/* gcc -Wall -DDNS_COMPR_TESTING domain_codec.c -o domain_codec && ./domain_codec */
+int main(int argc, char **argv)
+{
+ int len;
+ uint8_t *encoded;
+
+#define DNAME_DEC(encoded,pre) dname_dec((uint8_t*)(encoded), sizeof(encoded), (pre))
+ printf("'%s'\n", DNAME_DEC("\4host\3com\0", "test1:"));
+ printf("test2:'%s'\n", DNAME_DEC("\4host\3com\0\4host\3com\0", ""));
+ printf("test3:'%s'\n", DNAME_DEC("\4host\3com\0\xC0\0", ""));
+ printf("test4:'%s'\n", DNAME_DEC("\4host\3com\0\xC0\5", ""));
+ printf("test5:'%s'\n", DNAME_DEC("\4host\3com\0\xC0\5\1z\xC0\xA", ""));
+
+#define DNAME_ENC(cache,source,lenp) dname_enc((uint8_t*)(cache), sizeof(cache), (source), (lenp))
+ encoded = dname_enc(NULL, 0, "test.net", &len);
+ printf("test6:'%s' len:%d\n", dname_dec(encoded, len, ""), len);
+ encoded = DNAME_ENC("\3net\0", "test.net", &len);
+ printf("test7:'%s' len:%d\n", dname_dec(encoded, len, ""), len);
+ encoded = DNAME_ENC("\4test\3net\0", "test.net", &len);
+ printf("test8:'%s' len:%d\n", dname_dec(encoded, len, ""), len);
+ return 0;
+}
+#endif
projects / oweals / busybox.git / blobdiff