/**
* Extract information from SOAP fault tree.
*
* @param fault the XML <Fault> tree
* @param code where UPnP error code is written, if non-NULL
* @param error where address of UPnP error string is written, if non-NULL
*
* @attention
* The error string is pointing in the XML tree and will become invalid as
* soon as the tree is freed so it needs to be duplicated if it must persist.
*
* @return TRUE if OK, FALSE on error.
*/
static gboolean
upnp_ctrl_extract_fault(xnode_t *fault, int *code, const char **error)
{
xnode_t *fcode, *fstring, *detail, *uerror;
const char *parse_error = NULL;
g_assert(fault != NULL);
/*
* The SOAP specification for the <faultcode> element are very bad.
* Indeed, the content is a string bearing the *prefix* of the SOAP
* namespace, which is completely arbitrary and not accessible at this
* level since all nodes are normalized with their namespace, the prefix
* string being irrelevant once parsing is done. And namespace have no
* meaning in element *content*.
*
* Sure, we know we force the "s" prefix for SOAP, and most UPnP stacks
* are going to use that prefix as well, but matching the <faultcode>
* content to look for "s:Client" or "s:MustUnderstand" is just plain
* wrong, and a blatant encapsulation violation.
*
* So instead we look backwards in the string to find the first ':' and
* consider the tail part of the string, totally ignoring the prefix.
* That's a lousy parsing, but in practice it's going to work and should
* be safe since there's little choice anyway according to the SOAP
* specifications (meaning they could have just as well ignored the
* prefix in this string and just mandate "Client" or "MustUnderstand").
*
* Also note that <faultcode>, <faultstring> and <detail> elements are
* architected without any SOAP namespace. That's surprising.
*/
fcode = xnode_tree_find_depth(fault, 1, node_named_as,
deconstify_gchar(SOAP_FAULT_CODE));
if (NULL == fcode) {
parse_error = "cannot find <faultcode>";
goto error;
} else {
const char *value;
const char *name;
value = xnode_first_text(fcode);
if (NULL == value) {
parse_error = "<faultcode> does not contain text";
goto error;
}
/*
* We're only handling "Client" errors.
*/
name = strrchr(value, ':');
if (NULL == name) {
parse_error = "no ':' in fault code name";
goto error;
}
name++;
if (0 != strcmp(name, SOAP_CLIENT_FAULT)) {
parse_error = "not a Client fault";
goto error;
}
}
/*
* Here is a sample fault tree from the UPnP 1.0 architecture:
*
* <s:Fault>
* <faultcode>s:Client</faultcode>
* <faultstring>UPnPError</faultstring>
* <detail>
* <UPnpError xmlns="urn:schemas-upnp-org:control-1-0">
* <errorCode>error code</errorCode>
* <errorDescription>error string</errorDescription>
* </UPnPError>
* </detail>
* <s:Fault>
*
* Note that the UPnP tags are in the "urn:schemas-upnp-org:control-1-0"
* namespace.
*/
fstring = xnode_tree_find_depth(fault, 1, node_named_as,
deconstify_gchar(SOAP_FAULT_STRING));
if (NULL == fstring) {
parse_error = "no <faultstring> found";
goto error;
} else {
const char *value;
value = xnode_first_text(fstring);
if (NULL == value) {
parse_error = "<faultstring> does not contain text";
goto error;
}
if (0 != strcmp(value, SOAP_UPNP_ERROR)) {
parse_error = "<faultstring> is not an UPnP error";
goto error;
}
}
detail = xnode_tree_find_depth(fault, 1, node_named_as,
deconstify_gchar(SOAP_FAULT_DETAIL));
if (NULL == detail) {
parse_error = "no <detail> found";
goto error;
}
/*
* First child must be a <UPnpError> tag.
*/
uerror = xnode_first_child(detail);
if (xnode_is_element_named(uerror, UPNP_NS_ERROR, SOAP_UPNP_ERROR)) {
xnode_t *xn;
if (code != NULL) {
const char *value;
int err;
xn = xnode_tree_find_depth(uerror, 1,
node_named_as, deconstify_gchar(UPNP_ERROR_CODE));
if (NULL == xn) {
parse_error = "no <errorCode> found";
goto error;
}
value = xnode_first_text(xn);
if (NULL == value) {
parse_error = "<errorCode> doest not contain text";
goto error;
}
*code = parse_uint32(value, NULL, 10, &err);
if (err) {
parse_error = "cannot parse <errorCode> value";
goto error;
}
}
if (error != NULL) {
xn = xnode_tree_find_depth(uerror, 1,
node_named_as, deconstify_gchar(UPNP_ERROR_DESC));
*error = (NULL == xn) ? NULL : xnode_first_text(xn);
}
} else {
parse_error = "no <UPnPError> found";
goto error;
}
return TRUE;
error:
if (GNET_PROPERTY(upnp_debug))
g_warning("UPNP fault parsing error: %s", EMPTY_STRING(parse_error));
return FALSE;
}
/**
* Process the SOAP reply from the server.
*/
static void
soap_process_reply(soap_rpc_t *sr)
{
const char *buf;
vxml_parser_t *vp;
vxml_error_t e;
xnode_t *root = NULL;
xnode_t *xn = NULL;
const char *charset;
soap_rpc_check(sr);
if (sr->reply_len != 0 && (GNET_PROPERTY(soap_trace) & SOCK_TRACE_IN)) {
g_debug("----Got SOAP HTTP reply data from %s:", sr->url);
if (log_printable(LOG_STDERR)) {
fwrite(sr->reply_data, sr->reply_len, 1, stderr);
fputs("----End SOAP HTTP reply\n", stderr);
}
}
if (GNET_PROPERTY(soap_debug) > 2) {
g_debug("SOAP \"%s\" at \"%s\": processing reply (%lu byte%s) HTTP %d",
sr->action, sr->url, (unsigned long) sr->reply_len,
1 == sr->reply_len ? "" : "s", sr->http_code);
}
/*
* If we got a 2xx reply, we need to parse up to the <Body> element
* and then pass up the remaining to the user for parsing specific
* elemnts accordingly.
*
* Other reply codes indicate an error. On 4xx replies we may not
* have any XML to parse. On 5xx replies, we should usually have
* a <Fault> indication under the <Body>.
*
* The strategy used here is to parse the XML reply into a tree and then
* analyse the tree, ignoring the HTTP status code which is redundant.
*/
buf = header_get(sr->header, "Content-Type");
if (NULL == buf)
goto no_xml;
/*
* MIME type and subtypes are case-insensitive (see RFC 2616, section 3.7).
*/
if (
!http_field_starts_with(buf, SOAP_TEXT_REPLY, FALSE) &&
!http_field_starts_with(buf, SOAP_APPLICATION_REPLY, FALSE)
) {
if (GNET_PROPERTY(soap_debug)) {
g_debug("SOAP \"%s\" at \"%s\": got unexpected Content-Type: %s",
sr->action, sr->url, buf);
}
goto no_xml;
}
/*
* Extract charset if given.
*/
charset = http_parameter_get(buf, "charset");
/*
* Parse the SOAP envelope.
*/
vp = vxml_parser_make(sr->action, VXML_O_STRIP_BLANKS);
vxml_parser_add_data(vp, sr->reply_data, sr->reply_len);
if (!vxml_parser_set_charset(vp, charset)) {
g_warning("SOAP \"%s\" at \"%s\": ignoring unknown charset \"%s\"",
sr->action, sr->url, charset);
}
e = vxml_parse_tree(vp, &root);
vxml_parser_free(vp);
if (e != VXML_E_OK) {
if (GNET_PROPERTY(soap_debug)) {
g_debug("SOAP \"%s\" at \"%s\": cannot parse XML reply: %s",
sr->action, sr->url, vxml_strerror(e));
}
goto bad_xml;
}
g_assert(root != NULL);
/*
* Make sure we got a SOAP reply.
*/
if (!xnode_is_element_named(root, SOAP_NAMESPACE, SOAP_X_ENVELOPE))
goto not_soap;
/*
* Look for the <SOAP:Body> element.
*/
for (xn = xnode_first_child(root); TRUE; xn = xnode_next_sibling(xn)) {
if (NULL == xn || !xnode_within_namespace(xn, SOAP_NAMESPACE))
goto bad_soap;
if (0 == strcmp(SOAP_X_BODY, xnode_element_name(xn)))
break;
}
/*
* Inspect the first child of the <SOAP:Body> element.
*
* If it's a <SOAP:Fault>, go process it and return an error.
* If it's another SOAP tag, we have an unknown structure.
* Otherwise it's the reply, for user code to handle.
*/
xn = xnode_first_child(xn);
if (NULL == xn)
goto bad_soap;
if (xnode_is_element_named(xn, SOAP_NAMESPACE, SOAP_X_FAULT)) {
xnode_detach(xn);
soap_fault(sr, xn);
} else if (xnode_within_namespace(xn, SOAP_NAMESPACE)) {
goto bad_soap;
} else {
xnode_detach(xn);
soap_reply(sr, xn);
}
xnode_tree_free(root);
return;
not_soap:
if (GNET_PROPERTY(soap_debug)) {
g_debug("SOAP \"%s\" at \"%s\": unexpected root XML "
"element <%s:%s>",
sr->action, sr->url, EMPTY_STRING(xnode_element_ns(root)),
xnode_element_name(root));
}
xnode_tree_free(root);
/* FALL THROUGH */
no_xml:
soap_error(sr, SOAP_E_PROTOCOL);
return;
bad_soap:
if (GNET_PROPERTY(soap_debug)) {
g_debug("SOAP \"%s\" at \"%s\": unexpected XML structure",
sr->action, sr->url);
}
if (GNET_PROPERTY(soap_debug) > 1) {
g_debug("SOAP current node is %s", xnode_to_string(xn));
}
if (GNET_PROPERTY(soap_debug) > 2)
xfmt_tree_dump(root, stderr);
xnode_tree_free(root);
/* FALL THROUGH */
bad_xml:
soap_error(sr, SOAP_E_PROCESSING);
return;
}
