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/*
* Copyright 2016 Vincent Sanders <vince@netsurf-browser.org>
*
* This file is part of libnspsl
*
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*/
#include <stdint.h>
#include <string.h>
#include "nspsl.h"
#include "psl.inc"
#define DOMSEP '.'
static int matchlabel(int parent, const char *start, int len)
{
int clast = pnodes[parent].child_index + pnodes[parent].child_count;
int cidx; /*child node index */
int ridx = -1; /* index of match or -1 */
if (pnodes[parent].child_count != 0) {
/* there are child nodes present to scan */
for (cidx = pnodes[parent].child_index; cidx < clast; cidx++) {
if (pnodes[cidx].label == STAB_WILDCARD) {
/* wildcard match */
ridx = cidx;
} else {
if ((pnodes[cidx].label_len == len) &&
(strncasecmp(&stab[pnodes[cidx].label],
start,
len) == 0)) {
if ((pnodes[cidx].child_count == 1) &&
(pnodes[pnodes[cidx].child_index].label == STAB_EXCEPTION)) {
/* exception to previous */
ridx = -1;
} else {
ridx = cidx;
}
break;
}
}
}
}
return ridx;
}
/*
* Exported public API
*/
const char *nspsl_getpublicsuffix(const char *hostname)
{
int treeidx = 0; /* index to current tree node */
const char *elem_start;
const char *elem_end;
int lab_count = 0;
/* deal with obviously bad hostname */
if ((hostname == NULL) ||
(hostname[0]) == 0 ||
(hostname[0] == DOMSEP)) {
return NULL;
}
/* hostnames are ass backwards and we need to consider elemets
* from the end first.
*/
elem_end = hostname + strlen(hostname);
/* fqdn have a separator on the end */
if (elem_end[-1] == DOMSEP) {
elem_end--;
}
elem_start = elem_end;
/* extract the element and check for a match in our tree */
for(;;) {
/* find the start of the element */
while ((elem_start > hostname) && (*elem_start != DOMSEP)) {
elem_start--;
}
if (*elem_start == DOMSEP) {
elem_start++;
}
lab_count++;
/* search child nodes for label */
treeidx = matchlabel(treeidx, elem_start, elem_end - elem_start);
if (treeidx == -1) {
break;
}
if (elem_start == hostname) {
/* not valid */
return NULL;
}
elem_end = elem_start - 1;
elem_start = elem_end - 1;
}
/* The public suffix algorithm says: "the domain must match
* the public suffix plus one additional label." This
* requires there to be at least two labels so we need to
* check
*/
if (lab_count == 1) {
if (elem_start == hostname) {
elem_start = NULL;
} else {
/* strip the non matching part */
elem_start -= 2;
while (elem_start > hostname && *elem_start != DOMSEP) {
elem_start--;
}
if (*elem_start == DOMSEP)
elem_start++;
}
}
return elem_start;
}
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