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/*
20130604
20241207 - reformated using clang-format
Jan Mojzis
Public domain.
*/
#include "byte.h"
#include "iptostr.h"
static char *iptostr4(char *, const unsigned char *);
static char *iptostr6(char *, const unsigned char *);
/*
The 'iptostr(strbuf,ip)' function converts IP address 'ip'
from network byte order into the 0-terminated string.
The 'ip' length is always 16 bytes. The caller must
allocate at least IPTOSTR_LEN bytes for 'strbuf'.
*/
char *iptostr(char *strbuf, const unsigned char *ip) {
static char staticbuf[IPTOSTR_LEN];
if (!strbuf) strbuf = staticbuf; /* not thread-safe */
if (byte_isequal("\0\0\0\0\0\0\0\0\0\0\377\377", 12, ip)) {
return iptostr4(strbuf, ip + 12);
}
return iptostr6(strbuf, ip);
}
/* convert IPv4 address */
static char *iptostr4(char *strbuf, const unsigned char *ip) {
long long i, len = 0;
unsigned long long num;
for (i = 3; i >= 0; --i) {
num = ip[i];
do {
num /= 10;
++len;
} while (num);
if (i > 0) ++len;
}
strbuf += len;
for (i = 3; i >= 0; --i) {
num = ip[i];
do {
*--strbuf = '0' + (num % 10);
num /= 10;
} while (num);
if (i > 0) *--strbuf = '.';
}
while (len < IPTOSTR_LEN) strbuf[len++] = 0;
return strbuf;
}
/*
The 'ip' is splited into 8 16-bit blocks and
the 'countz' function counts successive zeros and
searches for largest zero-block.
'first' ... first position of the zero-block
'last' ... last position of the zero-block
*/
static void countz(long long *first, long long *last,
const unsigned long long *ip) {
long long i, j, e;
long long count[8];
for (i = 7; i >= 0; --i) count[i] = 0;
e = 8;
for (i = 7; i >= 0; --i) {
if (!ip[i]) {
for (j = i; j < e; ++j) ++count[j];
}
else { e = i; }
}
e = 0;
j = 0;
for (i = 7; i >= 0; --i) {
if (count[i]) {
if (count[i] >= e) {
e = count[i];
j = i;
}
}
}
*first = j - count[j] + 1;
*last = j;
}
/* convert IPv6 address */
static char *iptostr6(char *strbuf, const unsigned char *ip) {
long long first, last, i;
unsigned long long ip2[8];
char *s = strbuf;
for (i = 7; i >= 0; --i) {
ip2[i] = ip[2 * i];
ip2[i] <<= 8;
ip2[i] += ip[2 * i + 1];
}
countz(&first, &last, ip2);
strbuf += IPTOSTR_LEN - 1;
*strbuf = 0;
for (i = 7; i >= 0; --i) {
if (i <= last && i >= first && first != last) {
if (i == last) *--strbuf = ':';
if (i == 7) *--strbuf = ':';
continue;
}
do {
*--strbuf = "0123456789abcdef"[ip2[i] & 15];
ip2[i] >>= 4;
} while (ip2[i]);
if (i > 0) *--strbuf = ':';
}
i = strbuf - s;
byte_copy(s, IPTOSTR_LEN - i, strbuf);
byte_zero(s + IPTOSTR_LEN - i, i);
return s;
}
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