c14n.c

xml开源解析代码.版本为libxml2-2.6.29,可支持GB3212.网络消息发送XML时很有用.

 * with href="http://www.w3.org/XML/1998/namespace"
 *
 * Returns 1 if the node is default or 0 otherwise
 */

/* todo: make it a define? */
static int
xmlC14NIsXmlNs(xmlNsPtr ns)
{
    return ((ns != NULL) &&
            (xmlStrEqual(ns->prefix, BAD_CAST "xml")) &&
            (xmlStrEqual(ns->href,
                         BAD_CAST
                         "http://www.w3.org/XML/1998/namespace")));
}


/**
 * xmlC14NNsCompare:
 * @ns1:		the pointer to first namespace
 * @ns2: 		the pointer to second namespace
 *
 * Compares the namespaces by names (prefixes).
 *
 * Returns -1 if ns1 < ns2, 0 if ns1 == ns2 or 1 if ns1 > ns2.
 */
static int
xmlC14NNsCompare(xmlNsPtr ns1, xmlNsPtr ns2)
{
    if (ns1 == ns2)
        return (0);
    if (ns1 == NULL)
        return (-1);
    if (ns2 == NULL)
        return (1);

    return (xmlStrcmp(ns1->prefix, ns2->prefix));
}


/**
 * xmlC14NPrintNamespaces:
 * @ns:			the pointer to namespace
 * @ctx: 		the C14N context
 *
 * Prints the given namespace to the output buffer from C14N context.
 *
 * Returns 1 on success or 0 on fail.
 */
static int
xmlC14NPrintNamespaces(const xmlNsPtr ns, xmlC14NCtxPtr ctx)
{

    if ((ns == NULL) || (ctx == NULL)) {
        xmlC14NErrParam("writing namespaces");
        return 0;
    }

    if (ns->prefix != NULL) {
        xmlOutputBufferWriteString(ctx->buf, " xmlns:");
        xmlOutputBufferWriteString(ctx->buf, (const char *) ns->prefix);
        xmlOutputBufferWriteString(ctx->buf, "=\"");
    } else {
        xmlOutputBufferWriteString(ctx->buf, " xmlns=\"");
    }
    if(ns->href != NULL) {
	xmlOutputBufferWriteString(ctx->buf, (const char *) ns->href);
    }
    xmlOutputBufferWriteString(ctx->buf, "\"");
    return (1);
}

/**
 * xmlC14NProcessNamespacesAxis:
 * @ctx: 		the C14N context
 * @node:		the current node
 *
 * Prints out canonical namespace axis of the current node to the
 * buffer from C14N context as follows 
 *
 * Canonical XML v 1.0 (http://www.w3.org/TR/xml-c14n)
 *
 * Namespace Axis
 * Consider a list L containing only namespace nodes in the 
 * axis and in the node-set in lexicographic order (ascending). To begin 
 * processing L, if the first node is not the default namespace node (a node 
 * with no namespace URI and no local name), then generate a space followed 
 * by xmlns="" if and only if the following conditions are met:
 *    - the element E that owns the axis is in the node-set
 *    - The nearest ancestor element of E in the node-set has a default 
 *	    namespace node in the node-set (default namespace nodes always 
 *      have non-empty values in XPath)
 * The latter condition eliminates unnecessary occurrences of xmlns="" in 
 * the canonical form since an element only receives an xmlns="" if its 
 * default namespace is empty and if it has an immediate parent in the 
 * canonical form that has a non-empty default namespace. To finish 
 * processing  L, simply process every namespace node in L, except omit 
 * namespace node with local name xml, which defines the xml prefix, 
 * if its string value is http://www.w3.org/XML/1998/namespace.
 *
 * Exclusive XML Canonicalization v 1.0 (http://www.w3.org/TR/xml-exc-c14n)
 * Canonical XML applied to a document subset requires the search of the 
 * ancestor nodes of each orphan element node for attributes in the xml 
 * namespace, such as xml:lang and xml:space. These are copied into the 
 * element node except if a declaration of the same attribute is already 
 * in the attribute axis of the element (whether or not it is included in 
 * the document subset). This search and copying are omitted from the 
 * Exclusive XML Canonicalization method.
 *
 * Returns 0 on success or -1 on fail.
 */
static int
xmlC14NProcessNamespacesAxis(xmlC14NCtxPtr ctx, xmlNodePtr cur, int visible)
{
    xmlNodePtr n;
    xmlNsPtr ns, tmp;
    xmlListPtr list;
    int already_rendered;
    int has_empty_ns = 0;
    
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing namespaces axis (c14n)");
        return (-1);
    }

    /*
     * Create a sorted list to store element namespaces
     */
    list = xmlListCreate(NULL, (xmlListDataCompare) xmlC14NNsCompare);
    if (list == NULL) {
        xmlC14NErrInternal("creating namespaces list (c14n)");
        return (-1);
    }

    /* check all namespaces */
    for(n = cur; n != NULL; n = n->parent) {
	for(ns = n->nsDef; ns != NULL; ns = ns->next) {
	    tmp = xmlSearchNs(cur->doc, cur, ns->prefix);
	    
	    if((tmp == ns) && !xmlC14NIsXmlNs(ns) && xmlC14NIsVisible(ctx, ns, cur)) {
		already_rendered = xmlC14NVisibleNsStackFind(ctx->ns_rendered, ns);
		if(visible) {
        	    xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur);
		}
		if(!already_rendered) {
		    xmlListInsert(list, ns); 
		}
    		if(xmlStrlen(ns->prefix) == 0) {
		    has_empty_ns = 1;
		}
	    }
	}
    }
	
    /**
     * if the first node is not the default namespace node (a node with no 
     * namespace URI and no local name), then generate a space followed by 
     * xmlns="" if and only if the following conditions are met:
     *  - the element E that owns the axis is in the node-set
     *  - the nearest ancestor element of E in the node-set has a default 
     *     namespace node in the node-set (default namespace nodes always 
     *     have non-empty values in XPath)
     */
    if(visible && !has_empty_ns) {
        static xmlNs ns_default;

        memset(&ns_default, 0, sizeof(ns_default));
        if(!xmlC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default)) {
    	    xmlC14NPrintNamespaces(&ns_default, ctx);
	}
    }
	
    
    /* 
     * print out all elements from list 
     */
    xmlListWalk(list, (xmlListWalker) xmlC14NPrintNamespaces, (const void *) ctx);

    /* 
     * Cleanup
     */
    xmlListDelete(list);
    return (0);
}


/**
 * xmlExcC14NProcessNamespacesAxis:
 * @ctx: 		the C14N context
 * @node:		the current node
 *
 * Prints out exclusive canonical namespace axis of the current node to the
 * buffer from C14N context as follows 
 *
 * Exclusive XML Canonicalization
 * http://www.w3.org/TR/xml-exc-c14n
 *
 * If the element node is in the XPath subset then output the node in 
 * accordance with Canonical XML except for namespace nodes which are 
 * rendered as follows:
 *
 * 1. Render each namespace node iff:
 *    * it is visibly utilized by the immediate parent element or one of 
 *      its attributes, or is present in InclusiveNamespaces PrefixList, and
 *    * its prefix and value do not appear in ns_rendered. ns_rendered is 
 *      obtained by popping the state stack in order to obtain a list of 
 *      prefixes and their values which have already been rendered by 
 *      an output ancestor of the namespace node's parent element.
 * 2. Append the rendered namespace node to the list ns_rendered of namespace 
 * nodes rendered by output ancestors. Push ns_rendered on state stack and 
 * recurse.
 * 3. After the recursion returns, pop thestate stack.
 *
 *
 * Returns 0 on success or -1 on fail.
 */
static int
xmlExcC14NProcessNamespacesAxis(xmlC14NCtxPtr ctx, xmlNodePtr cur, int visible)
{
    xmlNsPtr ns;
    xmlListPtr list;
    xmlAttrPtr attr;
    int already_rendered;
    int has_empty_ns = 0;
    int has_visibly_utilized_empty_ns = 0;
    int has_empty_ns_in_inclusive_list = 0;
        
    if ((ctx == NULL) || (cur == NULL) || (cur->type != XML_ELEMENT_NODE)) {
        xmlC14NErrParam("processing namespaces axis (exc c14n)");
        return (-1);
    }

    if(!ctx->exclusive) {
        xmlC14NErrParam("processing namespaces axis (exc c14n)");
        return (-1);

    }

    /*
     * Create a sorted list to store element namespaces
     */
    list = xmlListCreate(NULL, (xmlListDataCompare) xmlC14NNsCompare);
    if (list == NULL) {
        xmlC14NErrInternal("creating namespaces list (exc c14n)");
        return (-1);
    }

    /* 
     * process inclusive namespaces:
     * All namespace nodes appearing on inclusive ns list are 
     * handled as provided in Canonical XML
     */
    if(ctx->inclusive_ns_prefixes != NULL) {
	xmlChar *prefix; 
	int i;
	
	for (i = 0; ctx->inclusive_ns_prefixes[i] != NULL; ++i) {
	    prefix = ctx->inclusive_ns_prefixes[i];
	    /*
	     * Special values for namespace with empty prefix
	     */
            if (xmlStrEqual(prefix, BAD_CAST "#default")
                || xmlStrEqual(prefix, BAD_CAST "")) {
                prefix = NULL;
		has_empty_ns_in_inclusive_list = 1;
            }
	
	    ns = xmlSearchNs(cur->doc, cur, prefix);	    
	    if((ns != NULL) && !xmlC14NIsXmlNs(ns) && xmlC14NIsVisible(ctx, ns, cur)) {
		already_rendered = xmlC14NVisibleNsStackFind(ctx->ns_rendered, ns);
		if(visible) {
    	    	    xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur);
		}
		if(!already_rendered) {
	    	    xmlListInsert(list, ns); 
		}
    		if(xmlStrlen(ns->prefix) == 0) {
		    has_empty_ns = 1;
		}
	    }
	}
    }
    
    /* add node namespace */
    if(cur->ns != NULL) {
	ns = cur->ns;
    } else {
        ns = xmlSearchNs(cur->doc, cur, NULL);
	has_visibly_utilized_empty_ns = 1;
    }
    if((ns != NULL) && !xmlC14NIsXmlNs(ns)) {
	if(visible && xmlC14NIsVisible(ctx, ns, cur)) { 
	    if(!xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, ns, ctx)) {
		xmlListInsert(list, ns);
	    }
	}
	if(visible) {
    	    xmlC14NVisibleNsStackAdd(ctx->ns_rendered, ns, cur); 
	}
	if(xmlStrlen(ns->prefix) == 0) {
	    has_empty_ns = 1;
	}
    }
    
        
    /* add attributes */
    for(attr = cur->properties; attr != NULL; attr = attr->next) {
        /* 
         * we need to check that attribute is visible and has non
         * default namespace (XML Namespaces: "default namespaces 
    	 * do not apply directly to attributes")	 
         */
	if((attr->ns != NULL) && !xmlC14NIsXmlNs(attr->ns) && xmlC14NIsVisible(ctx, attr, cur)) {
	    already_rendered = xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, attr->ns, ctx);
	    xmlC14NVisibleNsStackAdd(ctx->ns_rendered, attr->ns, cur); 
	    if(!already_rendered && visible) {
		xmlListInsert(list, attr->ns); 
	    }
	    if(xmlStrlen(attr->ns->prefix) == 0) {
		has_empty_ns = 1;
	    }
	} else if((attr->ns != NULL) && (xmlStrlen(attr->ns->prefix) == 0) && (xmlStrlen(attr->ns->href) == 0)) {
	    has_visibly_utilized_empty_ns = 1;
	}
    }

    /*
     * Process xmlns=""
     */
    if(visible && has_visibly_utilized_empty_ns && 
	    !has_empty_ns && !has_empty_ns_in_inclusive_list) {
        static xmlNs ns_default;

        memset(&ns_default, 0, sizeof(ns_default));
	
        already_rendered = xmlExcC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default, ctx);
	if(!already_rendered) {
    	    xmlC14NPrintNamespaces(&ns_default, ctx);
	}
    } else if(visible && !has_empty_ns && has_empty_ns_in_inclusive_list) {
        static xmlNs ns_default;

        memset(&ns_default, 0, sizeof(ns_default));
        if(!xmlC14NVisibleNsStackFind(ctx->ns_rendered, &ns_default)) {
    	    xmlC14NPrintNamespaces(&ns_default, ctx);
	}
    }

    

    /* 
     * print out all elements from list 
     */
    xmlListWalk(list, (xmlListWalker) xmlC14NPrintNamespaces, (const void *) ctx);

    /* 
     * Cleanup
     */
    xmlListDelete(list);
    return (0);
}


/**
 * xmlC14NAttrsCompare:
 * @attr1:		the pointer tls o first attr
 * @attr2: 		the pointer to second attr
 *
 * Prints the given attribute to the output buffer from C14N context.
 *
 * Returns -1 if attr1 < attr2, 0 if attr1 == attr2 or 1 if attr1 > attr2.
 */
static int
xmlC14NAttrsCompare(xmlAttrPtr attr1, xmlAttrPtr attr2)
{
    int ret = 0;

    /*
     * Simple cases
     */
    if (attr1 == attr2)
        return (0);
    if (attr1 == NULL)
        return (-1);
    if (attr2 == NULL)
        return (1);
    if (attr1->ns == attr2->ns) {
        return (xmlStrcmp(attr1->name, attr2->name));
    }

    /* 
     * Attributes in the default namespace are first
     * because the default namespace is not applied to
     * unqualified attributes
     */
    if (attr1->ns == NULL)
        return (-1);
    if (attr2->ns == NULL)
        return (1);
    if (attr1->ns->prefix == NULL)
        return (-1);
    if (attr2->ns->prefix == NULL)
        return (1);

    ret = xmlStrcmp(attr1->ns->href, attr2->ns->href);
    if (ret == 0) {
        ret = xmlStrcmp(attr1->name, attr2->name);
    }
    return (ret);
}


/**
 * xmlC14NPrintAttrs:
 * @attr:		the pointer to attr
 * @ctx: 		the C14N context
 *
 * Prints out canonical attribute urrent node to the
 * buffer from C14N context as follows 
 *
 * Canonical XML v 1.0 (http://www.w3.org/TR/xml-c14n)
 *
 * Returns 1 on success or 0 on fail.
 */
static int
xmlC14NPrintAttrs(const xmlAttrPtr attr, xmlC14NCtxPtr ctx)
{
    xmlChar *value;
    xmlChar *buffer;

    if ((attr == NULL) || (ctx == NULL)) {
        xmlC14NErrParam("writing attributes");
        return (0);
    }

    xmlOutputBufferWriteString(ctx->buf, " ");
    if (attr->ns != NULL && xmlStrlen(attr->ns->prefix) > 0) {
        xmlOutputBufferWriteString(ctx->buf,
                                   (const char *) attr->ns->prefix);
        xmlOutputBufferWriteString(ctx->buf, ":");
    }
    xmlOutputBufferWriteString(ctx->buf, (const char *) attr->name);
    xmlOutputBufferWriteString(ctx->buf, "=\"");

    value = xmlNodeListGetString(attr->doc, attr->children, 1);
    /* todo: should we log an error if value==NULL ? */
    if (value != NULL) {
        buffer = xmlC11NNormalizeAttr(value);
        xmlFree(value);
        if (buffer != NULL) {
            xmlOutputBufferWriteString(ctx->buf, (const char *) buffer);
            xmlFree(buffer);
        } else {
            xmlC14NErrInternal("normalizing attributes axis");
            return (0);
        }
    }
    xmlOutputBufferWriteString(ctx->buf, "\"");
    return (1);
}

/**
 * xmlC14NProcessAttrsAxis:
 * @ctx: 		the C14N context
 * @cur:		the current node
 * @parent_visible:	the visibility of parent node
 *
 * Prints out canonical attribute axis of the current node to the
 * buffer from C14N context as follows 
 *
 * Canonical XML v 1.0 (http://www.w3.org/TR/xml-c14n)
 *
 * Attribute Axis 
 * In lexicographic order (ascending), process each node that 
 * is in the element's attribute axis and in the node-set.
 * 
 * The processing of an element node E MUST be modified slightly 
 * when an XPath node-set is given as input and the element's 
 * parent is omitted from the node-set.
 *
 *
 * Exclusive XML Canonicalization v 1.0 (http://www.w3.org/TR/xml-exc-c14n)
 *