pidgin/pidgin

certificate: Use SHA256 fingerprints instead of SHA1
release-2.x.y
2017-03-06, dx
b3d0ba7c75f6
certificate: Use SHA256 fingerprints instead of SHA1

This meant adding a get_fingerprint_sha256 function to the certificate scheme
structs, which meant adding a struct_size member because we ran out of reserved
members there.

The API-facing purple_certificate_get_fingerprint_sha256() has a fallback
parameter to use sha1 if the SSL plugin doesn't implement this function
(probably an outdated installation, or a third party SSL plugin). When using
the function for display purposes, the fallback is disabled and it returns
NULL, but when using it to compare certificates it's better to have at least
the SHA1.

In functions like purple_certificate_display_x509(), some slight changes to
translatable strings would have been required. Since we're in a string freeze
right now, I avoided those by concatenating a language-neutral "SHA256: %s" at
the end of those messages. The SHA1 line used the word "fingerprint" but we
can't reuse that translation. This should be cleaned up after the release.
/**
* @file xmlnode.c XML DOM functions
*/
/* purple
*
* Purple is the legal property of its developers, whose names are too numerous
* to list here. Please refer to the COPYRIGHT file distributed with this
* source distribution.
*
* This program 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA
*/
/* A lot of this code at least resembles the code in libxode, but since
* libxode uses memory pools that we simply have no need for, I decided to
* write my own stuff. Also, re-writing this lets me be as lightweight
* as I want to be. Thank you libxode for giving me a good starting point */
#define _PURPLE_XMLNODE_C_
#include "internal.h"
#include "debug.h"
#include <libxml/parser.h>
#include <string.h>
#include <glib.h>
#include "dbus-maybe.h"
#include "util.h"
#include "xmlnode.h"
#ifdef _WIN32
# define NEWLINE_S "\r\n"
#else
# define NEWLINE_S "\n"
#endif
static xmlnode*
new_node(const char *name, XMLNodeType type)
{
xmlnode *node = g_new0(xmlnode, 1);
node->name = g_strdup(name);
node->type = type;
PURPLE_DBUS_REGISTER_POINTER(node, xmlnode);
return node;
}
xmlnode*
xmlnode_new(const char *name)
{
g_return_val_if_fail(name != NULL && *name != '\0', NULL);
return new_node(name, XMLNODE_TYPE_TAG);
}
xmlnode *
xmlnode_new_child(xmlnode *parent, const char *name)
{
xmlnode *node;
g_return_val_if_fail(parent != NULL, NULL);
g_return_val_if_fail(name != NULL && *name != '\0', NULL);
node = new_node(name, XMLNODE_TYPE_TAG);
xmlnode_insert_child(parent, node);
return node;
}
void
xmlnode_insert_child(xmlnode *parent, xmlnode *child)
{
g_return_if_fail(parent != NULL);
g_return_if_fail(child != NULL);
child->parent = parent;
if(parent->lastchild) {
parent->lastchild->next = child;
} else {
parent->child = child;
}
parent->lastchild = child;
}
void
xmlnode_insert_data(xmlnode *node, const char *data, gssize size)
{
xmlnode *child;
gsize real_size;
g_return_if_fail(node != NULL);
g_return_if_fail(data != NULL);
g_return_if_fail(size != 0);
real_size = size == -1 ? strlen(data) : (gsize)size;
child = new_node(NULL, XMLNODE_TYPE_DATA);
child->data = g_memdup(data, real_size);
child->data_sz = real_size;
xmlnode_insert_child(node, child);
}
void
xmlnode_remove_attrib(xmlnode *node, const char *attr)
{
xmlnode *attr_node, *sibling = NULL;
g_return_if_fail(node != NULL);
g_return_if_fail(attr != NULL);
attr_node = node->child;
while (attr_node) {
if(attr_node->type == XMLNODE_TYPE_ATTRIB &&
purple_strequal(attr_node->name, attr))
{
if (node->lastchild == attr_node) {
node->lastchild = sibling;
}
if (sibling == NULL) {
node->child = attr_node->next;
xmlnode_free(attr_node);
attr_node = node->child;
} else {
sibling->next = attr_node->next;
sibling = attr_node->next;
xmlnode_free(attr_node);
attr_node = sibling;
}
}
else
{
attr_node = attr_node->next;
}
sibling = attr_node;
}
}
void
xmlnode_remove_attrib_with_namespace(xmlnode *node, const char *attr, const char *xmlns)
{
xmlnode *attr_node, *sibling = NULL;
g_return_if_fail(node != NULL);
g_return_if_fail(attr != NULL);
for(attr_node = node->child; attr_node; attr_node = attr_node->next)
{
if(attr_node->type == XMLNODE_TYPE_ATTRIB &&
purple_strequal(attr, attr_node->name) &&
purple_strequal(xmlns, attr_node->xmlns))
{
if(sibling == NULL) {
node->child = attr_node->next;
} else {
sibling->next = attr_node->next;
}
if (node->lastchild == attr_node) {
node->lastchild = sibling;
}
xmlnode_free(attr_node);
return;
}
sibling = attr_node;
}
}
void
xmlnode_set_attrib(xmlnode *node, const char *attr, const char *value)
{
xmlnode_remove_attrib(node, attr);
xmlnode_set_attrib_full(node, attr, NULL, NULL, value);
}
void
xmlnode_set_attrib_with_namespace(xmlnode *node, const char *attr, const char *xmlns, const char *value)
{
xmlnode_set_attrib_full(node, attr, xmlns, NULL, value);
}
void
xmlnode_set_attrib_with_prefix(xmlnode *node, const char *attr, const char *prefix, const char *value)
{
xmlnode_set_attrib_full(node, attr, NULL, prefix, value);
}
void
xmlnode_set_attrib_full(xmlnode *node, const char *attr, const char *xmlns, const char *prefix, const char *value)
{
xmlnode *attrib_node;
g_return_if_fail(node != NULL);
g_return_if_fail(attr != NULL);
g_return_if_fail(value != NULL);
xmlnode_remove_attrib_with_namespace(node, attr, xmlns);
attrib_node = new_node(attr, XMLNODE_TYPE_ATTRIB);
attrib_node->data = g_strdup(value);
attrib_node->xmlns = g_strdup(xmlns);
attrib_node->prefix = g_strdup(prefix);
xmlnode_insert_child(node, attrib_node);
}
const char *
xmlnode_get_attrib(const xmlnode *node, const char *attr)
{
xmlnode *x;
g_return_val_if_fail(node != NULL, NULL);
g_return_val_if_fail(attr != NULL, NULL);
for(x = node->child; x; x = x->next) {
if(x->type == XMLNODE_TYPE_ATTRIB && purple_strequal(attr, x->name)) {
return x->data;
}
}
return NULL;
}
const char *
xmlnode_get_attrib_with_namespace(const xmlnode *node, const char *attr, const char *xmlns)
{
const xmlnode *x;
g_return_val_if_fail(node != NULL, NULL);
g_return_val_if_fail(attr != NULL, NULL);
for(x = node->child; x; x = x->next) {
if(x->type == XMLNODE_TYPE_ATTRIB &&
purple_strequal(attr, x->name) &&
purple_strequal(xmlns, x->xmlns)) {
return x->data;
}
}
return NULL;
}
void xmlnode_set_namespace(xmlnode *node, const char *xmlns)
{
g_return_if_fail(node != NULL);
g_free(node->xmlns);
node->xmlns = g_strdup(xmlns);
}
const char *xmlnode_get_namespace(xmlnode *node)
{
g_return_val_if_fail(node != NULL, NULL);
return node->xmlns;
}
void xmlnode_set_prefix(xmlnode *node, const char *prefix)
{
g_return_if_fail(node != NULL);
g_free(node->prefix);
node->prefix = g_strdup(prefix);
}
const char *xmlnode_get_prefix(const xmlnode *node)
{
g_return_val_if_fail(node != NULL, NULL);
return node->prefix;
}
xmlnode *xmlnode_get_parent(const xmlnode *child)
{
g_return_val_if_fail(child != NULL, NULL);
return child->parent;
}
void
xmlnode_free(xmlnode *node)
{
xmlnode *x, *y;
g_return_if_fail(node != NULL);
/* if we're part of a tree, remove ourselves from the tree first */
if(NULL != node->parent) {
if(node->parent->child == node) {
node->parent->child = node->next;
if (node->parent->lastchild == node)
node->parent->lastchild = node->next;
} else {
xmlnode *prev = node->parent->child;
while(prev && prev->next != node) {
prev = prev->next;
}
if(prev) {
prev->next = node->next;
if (node->parent->lastchild == node)
node->parent->lastchild = prev;
}
}
}
/* now free our children */
x = node->child;
while(x) {
y = x->next;
xmlnode_free(x);
x = y;
}
/* now dispose of ourselves */
g_free(node->name);
g_free(node->data);
g_free(node->xmlns);
g_free(node->prefix);
if(node->namespace_map)
g_hash_table_destroy(node->namespace_map);
PURPLE_DBUS_UNREGISTER_POINTER(node);
g_free(node);
}
xmlnode*
xmlnode_get_child(const xmlnode *parent, const char *name)
{
return xmlnode_get_child_with_namespace(parent, name, NULL);
}
xmlnode *
xmlnode_get_child_with_namespace(const xmlnode *parent, const char *name, const char *ns)
{
xmlnode *x, *ret = NULL;
char **names;
char *parent_name, *child_name;
g_return_val_if_fail(parent != NULL, NULL);
g_return_val_if_fail(name != NULL, NULL);
names = g_strsplit(name, "/", 2);
parent_name = names[0];
child_name = names[1];
for(x = parent->child; x; x = x->next) {
/* XXX: Is it correct to ignore the namespace for the match if none was specified? */
const char *xmlns = NULL;
if(ns)
xmlns = xmlnode_get_namespace(x);
if(x->type == XMLNODE_TYPE_TAG && purple_strequal(parent_name, x->name)
&& purple_strequal(ns, xmlns)) {
ret = x;
break;
}
}
if(child_name && ret)
ret = xmlnode_get_child(ret, child_name);
g_strfreev(names);
return ret;
}
char *
xmlnode_get_data(const xmlnode *node)
{
GString *str = NULL;
xmlnode *c;
g_return_val_if_fail(node != NULL, NULL);
for(c = node->child; c; c = c->next) {
if(c->type == XMLNODE_TYPE_DATA) {
if(!str)
str = g_string_new_len(c->data, c->data_sz);
else
str = g_string_append_len(str, c->data, c->data_sz);
}
}
if (str == NULL)
return NULL;
return g_string_free(str, FALSE);
}
char *
xmlnode_get_data_unescaped(const xmlnode *node)
{
char *escaped = xmlnode_get_data(node);
char *unescaped = escaped ? purple_unescape_html(escaped) : NULL;
g_free(escaped);
return unescaped;
}
static void
xmlnode_to_str_foreach_append_ns(const char *key, const char *value,
GString *buf)
{
if (*key) {
g_string_append_printf(buf, " xmlns:%s='%s'", key, value);
} else {
g_string_append_printf(buf, " xmlns='%s'", value);
}
}
static char *
xmlnode_to_str_helper(const xmlnode *node, int *len, gboolean formatting, int depth)
{
GString *text = g_string_new("");
const char *prefix;
const xmlnode *c;
char *node_name, *esc, *esc2, *tab = NULL;
gboolean need_end = FALSE, pretty = formatting;
g_return_val_if_fail(node != NULL, NULL);
if(pretty && depth) {
tab = g_strnfill(depth, '\t');
text = g_string_append(text, tab);
}
node_name = g_markup_escape_text(node->name, -1);
prefix = xmlnode_get_prefix(node);
if (prefix) {
g_string_append_printf(text, "<%s:%s", prefix, node_name);
} else {
g_string_append_printf(text, "<%s", node_name);
}
if (node->namespace_map) {
g_hash_table_foreach(node->namespace_map,
(GHFunc)xmlnode_to_str_foreach_append_ns, text);
} else if (node->xmlns) {
if(!node->parent || !purple_strequal(node->xmlns, node->parent->xmlns))
{
char *xmlns = g_markup_escape_text(node->xmlns, -1);
g_string_append_printf(text, " xmlns='%s'", xmlns);
g_free(xmlns);
}
}
for(c = node->child; c; c = c->next)
{
if(c->type == XMLNODE_TYPE_ATTRIB) {
const char *aprefix = xmlnode_get_prefix(c);
esc = g_markup_escape_text(c->name, -1);
esc2 = g_markup_escape_text(c->data, -1);
if (aprefix) {
g_string_append_printf(text, " %s:%s='%s'", aprefix, esc, esc2);
} else {
g_string_append_printf(text, " %s='%s'", esc, esc2);
}
g_free(esc);
g_free(esc2);
} else if(c->type == XMLNODE_TYPE_TAG || c->type == XMLNODE_TYPE_DATA) {
if(c->type == XMLNODE_TYPE_DATA)
pretty = FALSE;
need_end = TRUE;
}
}
if(need_end) {
g_string_append_printf(text, ">%s", pretty ? NEWLINE_S : "");
for(c = node->child; c; c = c->next)
{
if(c->type == XMLNODE_TYPE_TAG) {
int esc_len;
esc = xmlnode_to_str_helper(c, &esc_len, pretty, depth+1);
text = g_string_append_len(text, esc, esc_len);
g_free(esc);
} else if(c->type == XMLNODE_TYPE_DATA && c->data_sz > 0) {
esc = g_markup_escape_text(c->data, c->data_sz);
text = g_string_append(text, esc);
g_free(esc);
}
}
if(tab && pretty)
text = g_string_append(text, tab);
if (prefix) {
g_string_append_printf(text, "</%s:%s>%s", prefix, node_name, formatting ? NEWLINE_S : "");
} else {
g_string_append_printf(text, "</%s>%s", node_name, formatting ? NEWLINE_S : "");
}
} else {
g_string_append_printf(text, "/>%s", formatting ? NEWLINE_S : "");
}
g_free(node_name);
g_free(tab);
if(len)
*len = text->len;
return g_string_free(text, FALSE);
}
char *
xmlnode_to_str(const xmlnode *node, int *len)
{
return xmlnode_to_str_helper(node, len, FALSE, 0);
}
char *
xmlnode_to_formatted_str(const xmlnode *node, int *len)
{
char *xml, *xml_with_declaration;
g_return_val_if_fail(node != NULL, NULL);
xml = xmlnode_to_str_helper(node, len, TRUE, 0);
xml_with_declaration =
g_strdup_printf("<?xml version='1.0' encoding='UTF-8' ?>" NEWLINE_S NEWLINE_S "%s", xml);
g_free(xml);
if (len)
*len += sizeof("<?xml version='1.0' encoding='UTF-8' ?>" NEWLINE_S NEWLINE_S) - 1;
return xml_with_declaration;
}
struct _xmlnode_parser_data {
xmlnode *current;
gboolean error;
};
static void
xmlnode_parser_element_start_libxml(void *user_data,
const xmlChar *element_name, const xmlChar *prefix, const xmlChar *xmlns,
int nb_namespaces, const xmlChar **namespaces,
int nb_attributes, int nb_defaulted, const xmlChar **attributes)
{
struct _xmlnode_parser_data *xpd = user_data;
xmlnode *node;
int i, j;
if(!element_name || xpd->error) {
return;
} else {
if(xpd->current)
node = xmlnode_new_child(xpd->current, (const char*) element_name);
else
node = xmlnode_new((const char *) element_name);
xmlnode_set_namespace(node, (const char *) xmlns);
xmlnode_set_prefix(node, (const char *)prefix);
if (nb_namespaces != 0) {
node->namespace_map = g_hash_table_new_full(
g_str_hash, g_str_equal, g_free, g_free);
for (i = 0, j = 0; i < nb_namespaces; i++, j += 2) {
const char *key = (const char *)namespaces[j];
const char *val = (const char *)namespaces[j + 1];
g_hash_table_insert(node->namespace_map,
g_strdup(key ? key : ""), g_strdup(val ? val : ""));
}
}
for(i=0; i < nb_attributes * 5; i+=5) {
const char *name = (const char *)attributes[i];
const char *prefix = (const char *)attributes[i+1];
char *txt;
int attrib_len = attributes[i+4] - attributes[i+3];
char *attrib = g_strndup((const char *)attributes[i+3], attrib_len);
txt = attrib;
attrib = purple_unescape_text(txt);
g_free(txt);
xmlnode_set_attrib_full(node, name, NULL, prefix, attrib);
g_free(attrib);
}
xpd->current = node;
}
}
static void
xmlnode_parser_element_end_libxml(void *user_data, const xmlChar *element_name,
const xmlChar *prefix, const xmlChar *xmlns)
{
struct _xmlnode_parser_data *xpd = user_data;
if(!element_name || !xpd->current || xpd->error)
return;
if(xpd->current->parent) {
if(!xmlStrcmp((xmlChar*) xpd->current->name, element_name))
xpd->current = xpd->current->parent;
}
}
static void
xmlnode_parser_element_text_libxml(void *user_data, const xmlChar *text, int text_len)
{
struct _xmlnode_parser_data *xpd = user_data;
if(!xpd->current || xpd->error)
return;
if(!text || !text_len)
return;
xmlnode_insert_data(xpd->current, (const char*) text, text_len);
}
static void
xmlnode_parser_error_libxml(void *user_data, const char *msg, ...)
{
struct _xmlnode_parser_data *xpd = user_data;
char errmsg[2048];
va_list args;
xpd->error = TRUE;
va_start(args, msg);
vsnprintf(errmsg, sizeof(errmsg), msg, args);
va_end(args);
purple_debug_error("xmlnode", "Error parsing xml file: %s", errmsg);
}
static void
xmlnode_parser_structural_error_libxml(void *user_data, xmlErrorPtr error)
{
struct _xmlnode_parser_data *xpd = user_data;
if (error && (error->level == XML_ERR_ERROR ||
error->level == XML_ERR_FATAL)) {
xpd->error = TRUE;
purple_debug_error("xmlnode", "XML parser error for xmlnode %p: "
"Domain %i, code %i, level %i: %s",
user_data, error->domain, error->code, error->level,
error->message ? error->message : "(null)\n");
} else if (error)
purple_debug_warning("xmlnode", "XML parser error for xmlnode %p: "
"Domain %i, code %i, level %i: %s",
user_data, error->domain, error->code, error->level,
error->message ? error->message : "(null)\n");
else
purple_debug_warning("xmlnode", "XML parser error for xmlnode %p\n",
user_data);
}
static xmlSAXHandler xmlnode_parser_libxml = {
NULL, /* internalSubset */
NULL, /* isStandalone */
NULL, /* hasInternalSubset */
NULL, /* hasExternalSubset */
NULL, /* resolveEntity */
NULL, /* getEntity */
NULL, /* entityDecl */
NULL, /* notationDecl */
NULL, /* attributeDecl */
NULL, /* elementDecl */
NULL, /* unparsedEntityDecl */
NULL, /* setDocumentLocator */
NULL, /* startDocument */
NULL, /* endDocument */
NULL, /* startElement */
NULL, /* endElement */
NULL, /* reference */
xmlnode_parser_element_text_libxml, /* characters */
NULL, /* ignorableWhitespace */
NULL, /* processingInstruction */
NULL, /* comment */
NULL, /* warning */
xmlnode_parser_error_libxml, /* error */
NULL, /* fatalError */
NULL, /* getParameterEntity */
NULL, /* cdataBlock */
NULL, /* externalSubset */
XML_SAX2_MAGIC, /* initialized */
NULL, /* _private */
xmlnode_parser_element_start_libxml, /* startElementNs */
xmlnode_parser_element_end_libxml, /* endElementNs */
xmlnode_parser_structural_error_libxml, /* serror */
};
xmlnode *
xmlnode_from_str(const char *str, gssize size)
{
struct _xmlnode_parser_data *xpd;
xmlnode *ret;
gsize real_size;
g_return_val_if_fail(str != NULL, NULL);
real_size = size < 0 ? strlen(str) : (gsize)size;
xpd = g_new0(struct _xmlnode_parser_data, 1);
if (xmlSAXUserParseMemory(&xmlnode_parser_libxml, xpd, str, real_size) < 0) {
while(xpd->current && xpd->current->parent)
xpd->current = xpd->current->parent;
if(xpd->current)
xmlnode_free(xpd->current);
xpd->current = NULL;
}
ret = xpd->current;
if (xpd->error) {
ret = NULL;
if (xpd->current)
xmlnode_free(xpd->current);
}
g_free(xpd);
return ret;
}
xmlnode *
xmlnode_from_file(const char *dir,const char *filename, const char *description, const char *process)
{
gchar *filename_full;
GError *error = NULL;
gchar *contents = NULL;
gsize length;
xmlnode *node = NULL;
g_return_val_if_fail(dir != NULL, NULL);
purple_debug_info(process, "Reading file %s from directory %s\n",
filename, dir);
filename_full = g_build_filename(dir, filename, NULL);
if (!g_file_test(filename_full, G_FILE_TEST_EXISTS))
{
purple_debug_info(process, "File %s does not exist (this is not "
"necessarily an error)\n", filename_full);
g_free(filename_full);
return NULL;
}
if (!g_file_get_contents(filename_full, &contents, &length, &error))
{
purple_debug_error(process, "Error reading file %s: %s\n",
filename_full, error->message);
g_error_free(error);
}
if ((contents != NULL) && (length > 0))
{
node = xmlnode_from_str(contents, length);
/* If we were unable to parse the file then save its contents to a backup file */
if (node == NULL)
{
gchar *filename_temp, *filename_temp_full;
filename_temp = g_strdup_printf("%s~", filename);
filename_temp_full = g_build_filename(dir, filename_temp, NULL);
purple_debug_error("util", "Error parsing file %s. Renaming old "
"file to %s\n", filename_full, filename_temp);
purple_util_write_data_to_file_absolute(filename_temp_full, contents, length);
g_free(filename_temp_full);
g_free(filename_temp);
}
g_free(contents);
}
/* If we could not parse the file then show the user an error message */
if (node == NULL)
{
gchar *title, *msg;
title = g_strdup_printf(_("Error Reading %s"), filename);
msg = g_strdup_printf(_("An error was encountered reading your "
"%s. The file has not been loaded, and the old file "
"has been renamed to %s~."), description, filename_full);
purple_notify_error(NULL, NULL, title, msg);
g_free(title);
g_free(msg);
}
g_free(filename_full);
return node;
}
static void
xmlnode_copy_foreach_ns(gpointer key, gpointer value, gpointer user_data)
{
GHashTable *ret = (GHashTable *)user_data;
g_hash_table_insert(ret, g_strdup(key), g_strdup(value));
}
xmlnode *
xmlnode_copy(const xmlnode *src)
{
xmlnode *ret;
xmlnode *child;
xmlnode *sibling = NULL;
g_return_val_if_fail(src != NULL, NULL);
ret = new_node(src->name, src->type);
ret->xmlns = g_strdup(src->xmlns);
if (src->data) {
if (src->data_sz) {
ret->data = g_memdup(src->data, src->data_sz);
ret->data_sz = src->data_sz;
} else {
ret->data = g_strdup(src->data);
}
}
ret->prefix = g_strdup(src->prefix);
if (src->namespace_map) {
ret->namespace_map = g_hash_table_new_full(g_str_hash, g_str_equal,
g_free, g_free);
g_hash_table_foreach(src->namespace_map, xmlnode_copy_foreach_ns, ret->namespace_map);
}
for (child = src->child; child; child = child->next) {
if (sibling) {
sibling->next = xmlnode_copy(child);
sibling = sibling->next;
} else {
ret->child = sibling = xmlnode_copy(child);
}
sibling->parent = ret;
}
ret->lastchild = sibling;
return ret;
}
xmlnode *
xmlnode_get_next_twin(xmlnode *node)
{
xmlnode *sibling;
const char *ns = xmlnode_get_namespace(node);
g_return_val_if_fail(node != NULL, NULL);
g_return_val_if_fail(node->type == XMLNODE_TYPE_TAG, NULL);
for(sibling = node->next; sibling; sibling = sibling->next) {
/* XXX: Is it correct to ignore the namespace for the match if none was specified? */
const char *xmlns = NULL;
if(ns)
xmlns = xmlnode_get_namespace(sibling);
if(sibling->type == XMLNODE_TYPE_TAG && purple_strequal(node->name, sibling->name) &&
purple_strequal(ns, xmlns))
return sibling;
}
return NULL;
}