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/* IPv6 address-related routines
*/
#include "ip6addr.h"
#include <string.h>
#include <stdio.h>
#define digit(x) ((x)>='0'&&(x)<='9')
#define d2n(x) ((x)-'0')
/* parse address (prefix) in a form ffff:ffff:ffff:ffff:...
* granularity (bits) is 16, so the routine will return
* 16, 32, 48, 64, ... _bits_ on output or <0 on error.
* "an" is the max amount of bytes (not bits!) to store in *ap,
* should be even (2, 4, 6, 8, ...) and should be at least 2.
* The routine does support shortcuts like ffff::ffff.
*/
int ip6prefix(const char *s, ip6oct_t ap[IP6ADDR_FULL], char **np) {
static signed char hex_table[] = { /* map ascii to hex nibble value */
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
unsigned bytes = 0; /* number of bytes we filled in ap so far */
int zstart = -1; /* location of "::", if any */
int ret = -1;
/* memset is better be done here instead of zeroing the tail,
* since it's faster to zerofill full words.
* We may even change that to a by-word loop, since all
* addresses are aligned properly anyway */
memset(ap, 0, IP6ADDR_FULL);
if (s[0] == ':' && s[1] == ':') {
zstart = 0;
s += 2;
}
/* loop by semicolon-separated 2-byte (4 hex digits) fields */
for(;;) {
unsigned v = 0; /* 2-byte (4 hex digit) field */
const char *ss = s; /* save `s' value */
while ((*s & '\x80') == 0) {
int nibble = hex_table[(unsigned)*s];
if (nibble < 0)
break; /* not a hex digit */
v = (v << 4) + nibble;
if (v > 0xffff) /* a field can't be > 0xffff */
break;
++s;
}
if (ss == s || v > 0xffff) /* if no field has been consumed */
break;
ap[bytes++] = v >> 8;
ap[bytes++] = v & 0xff;
if (*s != ':' || bytes + 2 > IP6ADDR_FULL) {
ret = bytes * 8;
break;
}
++s;
if (zstart < 0 && *s == ':') {
zstart = bytes;
++s;
}
}
if (zstart >= 0) {
/* expand the "::" */
unsigned nzeros = IP6ADDR_FULL - bytes;
if (nzeros == 0)
ret = -1; /* illegal - no space for zeros */
else {
memmove(&ap[zstart + nzeros], &ap[zstart], bytes - zstart);
memset(&ap[zstart], 0, nzeros);
ret = 8 * IP6ADDR_FULL;
}
}
if (np)
*np = (char*)s;
else if (*s)
/* no success return if no 'tail' (np) pointer is given
* and the tail isn't empty */
ret = -1;
return ret;
}
/* Parse ip6 CIDR range in `s', store base
* in *ap (of size an bytes) and return number
* of _bits_ (may be 0) or <0 on error.
*/
int ip6cidr(const char *s, ip6oct_t ap[IP6ADDR_FULL], char **np) {
int bits = ip6prefix(s, ap, (char**)&s);
if (bits >= 0 && *s == '/') { /* parse /bits CIDR range */
++s;
if (!digit(*s))
bits = -1;
else {
bits = d2n(*s++);
while(digit(*s))
if ((bits = bits * 10 + d2n(*s++)) > 128) {
bits = -1;
break;
}
}
}
else if (bits == 16)
bits = -1; /* disallow bare number */
if (np)
*np = (char*)s;
else if (*s)
bits = -1;
return bits;
}
int ip6mask(const ip6oct_t *ap, ip6oct_t *bp, unsigned n, unsigned bits) {
unsigned i;
int r = 0;
i = bits / 8;
bits %= 8;
/* copy head */
if (bp && bp != ap)
memcpy(bp, ap, i < n ? i : n);
/* check the middle byte */
if (i < n && bits) {
if (ap[i] & (0xff >> bits))
r = 1;
if (bp)
bp[i] = ap[i] & (0xff << (8 - bits));
++i;
}
/* check-n-zero tail */
while(i < n) {
if (ap[i])
r = 1;
if (bp)
bp[i] = 0;
++i;
}
return r;
}
const char *ip6atos(const ip6oct_t *ap, unsigned an) {
static char buf[(4+1)*8+1];
unsigned awords = an / 2;
char *bp = buf;
unsigned nzeros = 0, zstart = 0, i;
if (awords > IP6ADDR_FULL / 2)
awords = IP6ADDR_FULL / 2;
/* find longest string of repeated zero words */
for (i = 0; i + nzeros < IP6ADDR_FULL / 2; i++) {
unsigned nz; /* count zero words */
for (nz = 0; i + nz < awords; nz++)
if (ap[2 * (i + nz)] != 0 || ap[2 * (i + nz) + 1] != 0)
break;
if (i + nz == awords)
nz += IP6ADDR_FULL / 2 - awords;
if (nz > 1 && nz > nzeros) {
nzeros = nz;
zstart = i;
}
}
for (i = 0; i < zstart; i++)
bp += sprintf(bp, ":%x", (((unsigned)ap[2*i]) << 8) + ap[2*i+1]);
if (nzeros) {
*bp++ = ':';
if (zstart == 0)
*bp++ = ':'; /* leading "::" */
if (zstart + nzeros == IP6ADDR_FULL / 2)
*bp++ = ':'; /* trailing "::" */
}
for (i += nzeros; i < awords; i++)
bp += sprintf(bp, ":%x", (((unsigned)ap[2*i]) << 8) + ap[2*i+1]);
for (; i < IP6ADDR_FULL / 2; i++) {
*bp++ = ':';
*bp++ = '0';
}
*bp = '\0';
return buf + 1;
}
#ifdef TEST
#include <stdlib.h>
/* our own version of assert()
*
* (mostly so that checks still happen even when compiled with
* -DNDEBUG)
*/
#define CHECK(expr) ((expr) ? (void) 0 : report_failure(#expr, __LINE__))
static void
report_failure(const char *expr, unsigned line)
{
printf("%s:%u: check `%s' failed\n", __FILE__, line, expr);
abort();
}
int main(int argc, char **argv) {
int i;
ip6oct_t a[IP6ADDR_FULL];
int bits;
char *np;
#define ip6tos(a,bits) (bits < 0 ? "err" : ip6atos(a,sizeof(a)))
for(i = 1; i < argc; ++i) {
char *s = argv[i];
printf("%s:\n", s);
bits = ip6prefix(s, a, NULL);
printf(" pfx: %s/%d\n", ip6tos(a, bits), bits);
bits = ip6prefix(s, a, &np);
printf(" pfx: %s/%d tail=`%s'\n", ip6tos(a, bits), bits, np);
bits = ip6cidr(s, a, NULL);
printf("cidr: %s/%d\n", ip6tos(a, bits), bits);
bits = ip6cidr(s, a, &np);
printf("cidr: %s/%d tail=`%s'\n", ip6tos(a, bits), bits, np);
if (bits >= 0) {
bits = ip6mask(a, a, IP6ADDR_FULL, bits);
printf("mask: %s (host=%d)\n", ip6atos(a, sizeof(a)), bits);
}
}
CHECK(ip6prefix("::1", a, NULL) == 128);
CHECK(strcmp(ip6atos(a, 128), "::1") == 0);
CHECK(ip6prefix("1::", a, NULL) == 128);
CHECK(strcmp(ip6atos(a, 128), "1::") == 0);
CHECK(ip6prefix("1::4:0:0:0:8", a, NULL) == 128);
CHECK(strcmp(ip6atos(a, 128), "1:0:0:4::8") == 0);
return 0;
}
#endif
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