ipv6_addr_to_str.c
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/*
* Copyright (c) 1996 by Internet Software Consortium.
* Copyright (c) 2015 by Martine Lenders <mlenders@inf.fu-berlin.de>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
/**
* @ingroup net_ipv6_addr
* @{
*
* @file
*
* @author Paul Vixie
* @author Martine Lenders <mlenders@inf.fu-berlin.de>
*/
#include <inttypes.h>
#include <string.h>
#include "byteorder.h"
#include "net/ipv4/addr.h"
#include "net/ipv6/addr.h"
/* Length of an IPv6 address in 16-bit words */
#define IPV6_ADDR_WORD_LEN (sizeof(ipv6_addr_t) / sizeof(uint16_t))
#define HEX_L "0123456789abcdef"
/* based on inet_ntop6() by Paul Vixie */
char *ipv6_addr_to_str(char *result, const ipv6_addr_t *addr, uint8_t result_len)
{
char tmp[IPV6_ADDR_MAX_STR_LEN], *tp;
struct {
int16_t base, len;
} best = { -1, 0}, cur = { -1, 0};
if ((result == NULL) || (addr == NULL)) {
return NULL;
}
/*
* Preprocess:
* Find the longest run of 0x0000's in address for :: shorthanding.
*/
for (uint8_t i = 0; i < IPV6_ADDR_WORD_LEN; i++) {
if (addr->u16[i].u16 == 0) {
if (cur.base == -1) {
cur.base = i;
cur.len = 1;
}
else {
cur.len++;
}
}
else {
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len) {
best = cur;
}
cur.base = -1;
}
}
}
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len) {
best = cur;
}
}
if (best.base != -1 && best.len < 2) {
best.base = -1;
}
/*
* Format the result.
*/
tp = tmp;
for (int i = 0; i < ((int)IPV6_ADDR_WORD_LEN);) {
/* Are we inside the best run of 0x00's? */
if (i == best.base) {
*tp++ = ':';
i += best.len;
continue;
}
/* Are we following an initial run of 0x00s or any real hex? */
if (i != 0) {
*tp++ = ':';
}
#ifdef MODULE_IPV4_ADDR
/* Is this address an encapsulated IPv4? */
if (i == 6 && best.base == 0 &&
(best.len == 6 || (best.len == 5 && addr->u16[5].u16 == 0xffff))) {
if (!ipv4_addr_to_str(tp, (const ipv4_addr_t *)&addr->u32[3],
sizeof(tmp) - (tp - tmp))) {
return (NULL);
}
tp += strlen(tp);
break;
}
#endif
if ((addr->u16[i].u8[0] & 0xf0) != 0x00) {
*tp++ = HEX_L[addr->u16[i].u8[0] >> 4];
*tp++ = HEX_L[addr->u16[i].u8[0] & 0x0f];
*tp++ = HEX_L[addr->u16[i].u8[1] >> 4];
}
else if ((addr->u16[i].u8[0] & 0x0f) != 0x00) {
*tp++ = HEX_L[addr->u16[i].u8[0] & 0x0f];
*tp++ = HEX_L[addr->u16[i].u8[1] >> 4];
}
else if ((addr->u16[i].u8[1] & 0xf0) != 0x00) {
*tp++ = HEX_L[addr->u16[i].u8[1] >> 4];
}
*tp++ = HEX_L[addr->u16[i].u8[1] & 0xf];
i++;
}
/* Was it a trailing run of 0x00's? */
if (best.base != -1 && (best.base + best.len) == IPV6_ADDR_WORD_LEN) {
*tp++ = ':';
}
*tp++ = '\0';
/*
* Check for overflow, copy, and we're done.
*/
if ((size_t)(tp - tmp) > result_len) {
return NULL;
}
strcpy(result, tmp);
return result;
}
/**
* @}
*/