netsurf/utils/idna.c
2016-11-23 15:43:37 +00:00

739 lines
17 KiB
C

/*
* Copyright 2014 Chris Young <chris@unsatisfactorysoftware.co.uk>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* NetSurf is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* \file
* NetSurf international domain name handling implementation.
*/
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <libutf8proc/utf8proc.h>
#include "utils/errors.h"
#include "utils/idna.h"
#include "utils/idna_props.h"
#include "utils/log.h"
#include "utils/punycode.h"
#include "utils/utf8.h"
#include "utils/utils.h"
int32_t idna_contexto[] = {
/* CONTEXTO codepoints which have a rule defined */
0x00b7, 0x0375, 0x05f3, 0x05f4, 0x30fb, 0x0660, 0x0661,
0x0662, 0x0663, 0x0664, 0x0665, 0x0666, 0x0667, 0x0668,
0x0669, 0x06f0, 0x06f1, 0x06f2, 0x06f3, 0x06f4, 0x06f5,
0x06f6, 0x06f7, 0x06f8, 0x06f9, 0
};
/**
* Convert punycode status into nserror.
*
* \param status The punycode status to convert.
* \return The corresponding nserror code for the status.
*/
static nserror punycode_status_to_nserror(enum punycode_status status)
{
nserror ret = NSERROR_NOMEM;
switch (status) {
case punycode_success:
ret = NSERROR_OK;
break;
case punycode_bad_input:
LOG("Bad input");
ret = NSERROR_BAD_ENCODING;
break;
case punycode_big_output:
LOG("Output too big");
ret = NSERROR_BAD_SIZE;
break;
case punycode_overflow:
LOG("Overflow");
ret = NSERROR_NOSPACE;
break;
default:
break;
}
return ret;
}
/**
* Find the IDNA property of a UCS-4 codepoint
*
* \param cp Unicode codepoint
* \return IDNA property
*/
static idna_property idna__cp_property(int32_t cp)
{
const idna_table *t;
t = idna_derived;
while (t->p.property) {
if ((cp >= t->start) && (cp <= t->end)) {
return t->p.property;
}
t++;
};
return IDNA_P_DISALLOWED;
}
/**
* Find the Joining_Type property of a UCS-4 codepoint
*
* \param cp Unicode codepoint
* \return JT property
*/
static idna_unicode_jt idna__jt_property(int32_t cp)
{
const idna_table *t;
t = idna_joiningtype;
while (t->p.jt) {
if ((cp >= t->start) && (cp <= t->end)) {
return t->p.jt;
}
t++;
};
return IDNA_UNICODE_JT_U;
}
/**
* Check if a CONTEXTO codepoint has a rule defined
*
* \param cp Unicode codepoint
* \return true if a rule is defined
*/
static bool idna__contexto_rule(int32_t cp)
{
int32_t *t;
for (t = idna_contexto; *t != 0; t++) {
if (*t == cp) {
return true;
}
}
return false;
}
/**
* Check if a CONTEXTJ codepoint has a rule defined,
* and conforms to that rule.
*
* \param label UCS-4 string
* \param index character in the string which is CONTEXTJ
* \param len The length of the label
* \return true if conforming
*/
static bool idna__contextj_rule(int32_t *label, int index, size_t len)
{
const utf8proc_property_t *unicode_props;
idna_unicode_jt joining_type;
int i;
bool match;
/* These CONTEXTJ rules are defined at
* http://www.iana.org/assignments/idna-tables-5.2.0/idna-tables-5.2.0.xml
*/
if (label[index] == 0x200c) {
if (index == 0) {
return false; /* No previous character */
}
unicode_props = utf8proc_get_property(label[index - 1]);
if (unicode_props->combining_class == IDNA_UNICODE_CCC_VIRAMA) {
return true;
}
match = false;
for (i = 0; i < (index - 1); i++) {
joining_type = idna__jt_property(label[i]);
if (((joining_type == IDNA_UNICODE_JT_L) ||
(joining_type == IDNA_UNICODE_JT_D)) &&
(idna__jt_property(label[i+1]) == IDNA_UNICODE_JT_T)) {
match = true;
break;
}
}
if (match == false) {
return false;
}
if (idna__jt_property(label[index+1]) != IDNA_UNICODE_JT_T) {
return false;
}
for (i = (index + 1); i < (int)len; i++) {
joining_type = idna__jt_property(label[i]);
if ((joining_type == IDNA_UNICODE_JT_R) ||
(joining_type == IDNA_UNICODE_JT_D)) {
return true;
}
}
return false;
} else if (label[index] == 0x200d) {
if (index == 0) {
return false; /* No previous character */
}
unicode_props = utf8proc_get_property(label[index - 1]);
if (unicode_props->combining_class == IDNA_UNICODE_CCC_VIRAMA) {
return true;
}
return false;
}
/* No rule defined */
return false;
}
/**
* Convert a UTF-8 string to UCS-4
*
* \param utf8_label UTF-8 string containing host label
* \param len Length of host label (in bytes)
* \param ucs4_label Pointer to update with the output
* \param ucs4_len Pointer to update with the length
* \return NSERROR_OK on success, appropriate error otherwise
*
* If return value != NSERROR_OK, output will be left untouched.
*/
static nserror
idna__utf8_to_ucs4(const char *utf8_label,
size_t len,
int32_t **ucs4_label,
size_t *ucs4_len)
{
int32_t *nfc_label;
ssize_t nfc_size;
nfc_label = malloc(len * 4);
if (nfc_label == NULL) {
return NSERROR_NOMEM;
}
nfc_size = utf8proc_decompose((const uint8_t *)utf8_label, len,
nfc_label, len * 4, UTF8PROC_STABLE | UTF8PROC_COMPOSE);
if (nfc_size < 0) {
return NSERROR_NOMEM;
}
nfc_size = utf8proc_normalize_utf32(nfc_label, nfc_size,
UTF8PROC_STABLE | UTF8PROC_COMPOSE);
if (nfc_size < 0) {
return NSERROR_NOMEM;
}
*ucs4_label = nfc_label;
*ucs4_len = nfc_size;
return NSERROR_OK;
}
/**
* Convert a UCS-4 string to UTF-8
*
* \param ucs4_label UCS-4 string containing host label
* \param ucs4_len Length of host label (in bytes)
* \param utf8_label Pointer to update with the output
* \param utf8_len Pointer to update with the length
* \return NSERROR_OK on success, appropriate error otherwise
*
* If return value != NSERROR_OK, output will be left untouched.
*/
static nserror
idna__ucs4_to_utf8(const int32_t *ucs4_label,
size_t ucs4_len,
char **utf8_label,
size_t *utf8_len)
{
int32_t *nfc_label;
ssize_t nfc_size = ucs4_len;
nfc_label = malloc(1 + ucs4_len * 4);
if (nfc_label == NULL) {
return NSERROR_NOMEM;
}
memcpy(nfc_label, ucs4_label, ucs4_len * 4);
nfc_size = utf8proc_reencode(nfc_label, ucs4_len,
UTF8PROC_STABLE | UTF8PROC_COMPOSE);
if (nfc_size < 0) {
return NSERROR_NOMEM;
}
*utf8_label = (char *)nfc_label;
*utf8_len = nfc_size;
return NSERROR_OK;
}
/**
* Convert a host label in UCS-4 to an ACE version
*
* \param ucs4_label UCS-4 NFC string containing host label
* \param len Length of host label (in characters/codepoints)
* \param ace_label ASCII-compatible encoded version
* \param out_len Length of ace_label
* \return NSERROR_OK on success, appropriate error otherwise
*
* If return value != NSERROR_OK, output will be left untouched.
*/
static nserror
idna__ucs4_to_ace(int32_t *ucs4_label,
size_t len,
char **ace_label,
size_t *out_len)
{
char punycode[65]; /* max length of host label + NULL */
size_t output_length = 60; /* punycode length - 4 - 1 */
nserror ret;
punycode[0] = 'x';
punycode[1] = 'n';
punycode[2] = '-';
punycode[3] = '-';
ret = punycode_status_to_nserror(punycode_encode(len,
(const punycode_uint *)ucs4_label, NULL,
&output_length, punycode + 4));
if (ret != NSERROR_OK) {
return ret;
}
output_length += SLEN("xn--");
punycode[output_length] = '\0';
*ace_label = strdup(punycode);
*out_len = output_length;
return NSERROR_OK;
}
/**
* Convert a host label in ACE format to UCS-4
*
* \param ace_label ASCII string containing host label
* \param ace_len Length of host label
* \param ucs4_label Pointer to hold UCS4 decoded version
* \param ucs4_len Pointer to hold length of ucs4_label
* \return NSERROR_OK on success, appropriate error otherwise
*
* If return value != NSERROR_OK, output will be left untouched.
*/
static nserror
idna__ace_to_ucs4(const char *ace_label,
size_t ace_len,
int32_t **ucs4_label,
size_t *ucs4_len)
{
int32_t *ucs4;
nserror ret;
size_t output_length = ace_len; /* never exceeds input length */
/* The header should always have been checked before calling */
assert((ace_label[0] == 'x') && (ace_label[1] == 'n') &&
(ace_label[2] == '-') && (ace_label[3] == '-'));
ucs4 = malloc(output_length * 4);
if (ucs4 == NULL) {
return NSERROR_NOMEM;
}
ret = punycode_status_to_nserror(punycode_decode(ace_len - 4,
ace_label + 4, &output_length, (punycode_uint *)ucs4, NULL));
if (ret != NSERROR_OK) {
free(ucs4);
return ret;
}
ucs4[output_length] = '\0';
*ucs4_label = ucs4;
*ucs4_len = output_length;
return NSERROR_OK;
}
/**
* Find the length of a host label
*
* \param host String containing a host or FQDN
* \param max_length Length of host string to search (in bytes)
* \return Distance to next separator character or end of string
*/
static size_t idna__host_label_length(const char *host, size_t max_length)
{
const char *p = host;
size_t length = 0;
while (length < max_length) {
if ((*p == '.') || (*p == ':') || (*p == '\0')) {
break;
}
length++;
p++;
}
return length;
}
/**
* Check if a host label is valid for IDNA2008
*
* \param label Host label to check (UCS-4)
* \param len Length of host label (in characters/codepoints)
* \return true if compliant, false otherwise
*/
static bool idna__is_valid(int32_t *label, size_t len)
{
const utf8proc_property_t *unicode_props;
idna_property idna_prop;
size_t i = 0;
/* 1. Check that the string is NFC.
* This check is skipped as the conversion to Unicode
* does normalisation as part of the conversion.
*/
/* 2. Check characters 3 and 4 are not '--'. */
if ((label[2] == 0x002d) && (label[3] == 0x002d)) {
LOG("Check failed: characters 2 and 3 are '--'");
return false;
}
/* 3. Check the first character is not a combining mark */
unicode_props = utf8proc_get_property(label[0]);
if ((unicode_props->category == UTF8PROC_CATEGORY_MN) ||
(unicode_props->category == UTF8PROC_CATEGORY_MC) ||
(unicode_props->category == UTF8PROC_CATEGORY_ME)) {
LOG("Check failed: character 0 is a combining mark");
return false;
}
for (i = 0; i < len; i++) {
idna_prop = idna__cp_property(label[i]);
/* 4. Check characters not DISALLOWED by RFC5892 */
if (idna_prop == IDNA_P_DISALLOWED) {
LOG("Check failed: character %" PRIsizet " (%x) is DISALLOWED", i, label[i]);
return false;
}
/* 5. Check CONTEXTJ characters conform to defined rules */
if (idna_prop == IDNA_P_CONTEXTJ) {
if (idna__contextj_rule(label, i, len) == false) {
LOG("Check failed: character %" PRIsizet " (%x) does not conform to CONTEXTJ rule", i, label[i]);
return false;
}
}
/* 6. Check CONTEXTO characters have a rule defined */
/** \todo optionally we can check conformance to this rule */
if (idna_prop == IDNA_P_CONTEXTO) {
if (idna__contexto_rule(label[i]) == false) {
LOG("Check failed: character %" PRIsizet " (%x) has no CONTEXTO rule defined", i, label[i]);
return false;
}
}
/* 7. Check characters are not UNASSIGNED */
if (idna_prop == IDNA_P_UNASSIGNED) {
LOG("Check failed: character %" PRIsizet " (%x) is UNASSIGNED", i, label[i]);
return false;
}
/** \todo 8. (optionally) check Bidi compliance */
}
return true;
}
/**
* Check if a host label is LDH
*
* \param label Host label to check
* \param len Length of host label
* \return true if LDH compliant, false otherwise
*/
static bool idna__is_ldh(const char *label, size_t len)
{
const char *p = label;
size_t i = 0;
/* Check for leading or trailing hyphens */
if ((p[0] == '-') || (p[len - 1] == '-'))
return false;
/* Check for non-alphanumeric, non-hyphen characters */
for (i = 0; i < len; p++) {
i++;
if (*p == '-') continue;
if ((*p >= '0') && (*p <= '9')) continue;
if ((*p >= 'a') && (*p <= 'z')) continue;
if ((*p >= 'A') && (*p <= 'Z')) continue;
return false;
}
return true;
}
/**
* Check if a host label appears to be ACE
*
* \param label Host label to check
* \param len Length of host label
* \return true if ACE compliant, false otherwise
*/
static bool idna__is_ace(const char *label, size_t len)
{
/* Check it is a valid DNS string */
if (idna__is_ldh(label, len) == false) {
return false;
}
/* Check the ACE prefix is present */
if ((label[0] == 'x') && (label[1] == 'n') &&
(label[2] == '-') && (label[3] == '-')) {
return true;
}
return false;
}
/**
* Verify an ACE label is valid
*
* \param label Host label to check
* \param len Length of label
* \return true if valid, false otherwise
*/
static bool idna__verify(const char *label, size_t len)
{
nserror error;
int32_t *ucs4;
char *ace;
ssize_t ucs4_len;
size_t u_ucs4_len, ace_len;
/* Convert our ACE label back to UCS-4 */
error = idna__ace_to_ucs4(label, len, &ucs4, &u_ucs4_len);
if (error != NSERROR_OK) {
return false;
}
/* Perform NFC normalisation */
ucs4_len = utf8proc_normalize_utf32(ucs4, u_ucs4_len,
UTF8PROC_STABLE | UTF8PROC_COMPOSE);
if (ucs4_len < 0) {
free(ucs4);
return false;
}
/* Convert the UCS-4 label back to ACE */
error = idna__ucs4_to_ace(ucs4, (size_t)ucs4_len,
&ace, &ace_len);
free(ucs4);
if (error != NSERROR_OK) {
return false;
}
/* Check if it matches the input */
if ((len == ace_len) && (strncmp(label, ace, len) == 0)) {
free(ace);
return true;
}
LOG("Re-encoded ACE label %s does not match input", ace);
free(ace);
return false;
}
/* exported interface documented in idna.h */
nserror
idna_encode(const char *host, size_t len, char **ace_host, size_t *ace_len)
{
nserror error;
int32_t *ucs4_host;
size_t label_len, output_len, ucs4_len, fqdn_len = 0;
char fqdn[256];
char *output, *fqdn_p = fqdn;
label_len = idna__host_label_length(host, len);
if (label_len == 0) {
return NSERROR_BAD_URL;
}
while (label_len != 0) {
if (idna__is_ldh(host, label_len) == false) {
/* This string is IDN or invalid */
/* Convert to Unicode */
if ((error = idna__utf8_to_ucs4(host, label_len,
&ucs4_host, &ucs4_len)) != NSERROR_OK) {
return error;
}
/* Check this is valid for conversion */
if (idna__is_valid(ucs4_host, ucs4_len) == false) {
free(ucs4_host);
return NSERROR_BAD_URL;
}
/* Convert to ACE */
error = idna__ucs4_to_ace(ucs4_host, ucs4_len,
&output, &output_len);
free(ucs4_host);
if (error != NSERROR_OK) {
return error;
}
strncpy(fqdn_p, output, output_len);
free(output);
fqdn_p += output_len;
fqdn_len += output_len;
} else {
/* This is already a DNS-valid ASCII string */
if ((idna__is_ace(host, label_len) == true) &&
(idna__verify(host, label_len) == false)) {
LOG("Cannot verify ACE label %s", host);
return NSERROR_BAD_URL;
}
strncpy(fqdn_p, host, label_len);
fqdn_p += label_len;
fqdn_len += label_len;
}
*fqdn_p = '.';
fqdn_p++;
fqdn_len++;
host += label_len;
if ((*host == '\0') || (*host == ':')) {
break;
}
host++;
len = len - label_len - 1;
label_len = idna__host_label_length(host, len);
}
fqdn_p--;
*fqdn_p = '\0';
*ace_host = strdup(fqdn);
*ace_len = fqdn_len - 1; /* last character is NULL */
return NSERROR_OK;
}
/* exported interface documented in idna.h */
nserror
idna_decode(const char *ace_host, size_t ace_len, char **host, size_t *host_len)
{
nserror error;
int32_t *ucs4_host;
size_t label_len, output_len, ucs4_len, fqdn_len = 0;
char fqdn[256];
char *output, *fqdn_p = fqdn;
label_len = idna__host_label_length(ace_host, ace_len);
if (label_len == 0) {
return NSERROR_BAD_URL;
}
while (label_len != 0) {
if (idna__is_ace(ace_host, label_len) == true) {
/* This string is DNS-valid and (probably) encoded */
/* Decode to Unicode */
error = idna__ace_to_ucs4(ace_host, label_len,
&ucs4_host, &ucs4_len);
if (error != NSERROR_OK) {
return error;
}
/* Convert to UTF-8 */
error = idna__ucs4_to_utf8(ucs4_host, ucs4_len,
&output, &output_len);
free(ucs4_host);
if (error != NSERROR_OK) {
return error;
}
memcpy(fqdn_p, output, output_len * 4);
free(output);
fqdn_p += output_len;
fqdn_len += output_len;
} else {
/* Not ACE */
memcpy(fqdn_p, ace_host, label_len);
fqdn_p += label_len;
fqdn_len += label_len;
}
*fqdn_p = '.';
fqdn_p++;
fqdn_len++;
ace_host += label_len;
if ((*ace_host == '\0') || (*ace_host == ':')) {
break;
}
ace_host++;
ace_len = ace_len - label_len - 1;
label_len = idna__host_label_length(ace_host, ace_len);
}
fqdn_p--;
*fqdn_p = '\0';
*host = strdup(fqdn);
*host_len = fqdn_len - 1; /* last character is NULL */
return NSERROR_OK;
}