src/parser_xml.c

/**
 * @file parser_xml.c
 * @author Radek Krejci <rkrejci@cesnet.cz>
 * @brief XML data parser for libyang
 *
 * Copyright (c) 2019 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "common.h"
#include "context.h"
#include "dict.h"
#include "in_internal.h"
#include "log.h"
#include "parser_data.h"
#include "parser_internal.h"
#include "plugins_exts.h"
#include "set.h"
#include "tree.h"
#include "tree_data.h"
#include "tree_data_internal.h"
#include "tree_schema.h"
#include "tree_schema_internal.h"
#include "validation.h"
#include "xml.h"

void
lyd_xml_ctx_free(struct lyd_ctx *lydctx)
{
    struct lyd_xml_ctx *ctx = (struct lyd_xml_ctx *)lydctx;

    lyd_ctx_free(lydctx);
    lyxml_ctx_free(ctx->xmlctx);
    free(ctx);
}

/**
 * @brief Parse and create XML metadata.
 *
 * @param[in] lydctx XML data parser context.
 * @param[in] sparent Schema node of the parent.
 * @param[out] meta List of created metadata instances.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_metadata(struct lyd_xml_ctx *lydctx, const struct lysc_node *sparent, struct lyd_meta **meta)
{
    LY_ERR ret = LY_SUCCESS;
    const struct lyxml_ns *ns;
    struct lys_module *mod;
    const char *name;
    size_t name_len;
    LY_ARRAY_COUNT_TYPE u;
    ly_bool filter_attrs = 0;
    struct lyxml_ctx *xmlctx = lydctx->xmlctx;

    *meta = NULL;

    /* check for NETCONF filter unqualified attributes */
    LY_ARRAY_FOR(sparent->exts, u) {
        if (!strcmp(sparent->exts[u].def->name, "get-filter-element-attributes") &&
                !strcmp(sparent->exts[u].def->module->name, "ietf-netconf")) {
            filter_attrs = 1;
            break;
        }
    }

    while (xmlctx->status == LYXML_ATTRIBUTE) {
        if (!xmlctx->prefix_len) {
            /* in XML all attributes must be prefixed except NETCONF filter ones marked by an extension */
            if (filter_attrs && (!ly_strncmp("type", xmlctx->name, xmlctx->name_len) ||
                    !ly_strncmp("select", xmlctx->name, xmlctx->name_len))) {
                mod = ly_ctx_get_module_implemented(xmlctx->ctx, "ietf-netconf");
                if (!mod) {
                    LOGVAL(xmlctx->ctx, LYVE_REFERENCE,
                            "Missing (or not implemented) YANG module \"ietf-netconf\" for special filter attributes.");
                    ret = LY_ENOTFOUND;
                    goto cleanup;
                }
                goto create_meta;
            }

            if (lydctx->parse_opts & LYD_PARSE_STRICT) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Missing mandatory prefix for XML metadata \"%.*s\".",
                        (int)xmlctx->name_len, xmlctx->name);
                ret = LY_EVALID;
                goto cleanup;
            }

            /* skip attr */
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            assert(xmlctx->status == LYXML_ATTR_CONTENT);
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            continue;
        }

        /* get namespace of the attribute to find its annotation definition */
        ns = lyxml_ns_get(&xmlctx->ns, xmlctx->prefix, xmlctx->prefix_len);
        if (!ns) {
            /* unknown namespace, XML error */
            LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)xmlctx->prefix_len, xmlctx->prefix);
            ret = LY_ENOTFOUND;
            goto cleanup;
        }

        /* get the module with metadata definition */
        mod = ly_ctx_get_module_implemented_ns(xmlctx->ctx, ns->uri);
        if (!mod) {
            if (lydctx->parse_opts & LYD_PARSE_STRICT) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE,
                        "Unknown (or not implemented) YANG module with namespace \"%s\" for metadata \"%.*s%s%.*s\".",
                        ns->uri, (int)xmlctx->prefix_len, xmlctx->prefix, xmlctx->prefix_len ? ":" : "",
                        (int)xmlctx->name_len, xmlctx->name);
                ret = LY_ENOTFOUND;
                goto cleanup;
            }

            /* skip attr */
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            assert(xmlctx->status == LYXML_ATTR_CONTENT);
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            continue;
        }

create_meta:
        /* remember meta name and get its content */
        name = xmlctx->name;
        name_len = xmlctx->name_len;
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
        assert(xmlctx->status == LYXML_ATTR_CONTENT);

        /* create metadata */
        ret = lyd_parser_create_meta((struct lyd_ctx *)lydctx, NULL, meta, mod, name, name_len, xmlctx->value,
                xmlctx->value_len, &xmlctx->dynamic, LY_VALUE_XML, &xmlctx->ns, LYD_HINT_DATA, sparent);
        LY_CHECK_GOTO(ret, cleanup);

        /* next attribute */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
    }

cleanup:
    if (ret) {
        lyd_free_meta_siblings(*meta);
        *meta = NULL;
    }
    return ret;
}

static LY_ERR
lydxml_attrs(struct lyxml_ctx *xmlctx, struct lyd_attr **attr)
{
    LY_ERR ret = LY_SUCCESS;
    const struct lyxml_ns *ns;
    void *val_prefix_data;
    LY_VALUE_FORMAT format;
    struct lyd_attr *attr2;
    const char *name, *prefix;
    size_t name_len, prefix_len;

    assert(attr);
    *attr = NULL;

    while (xmlctx->status == LYXML_ATTRIBUTE) {
        if (*attr) {
            attr2 = *attr;
        } else {
            attr2 = NULL;
        }

        /* remember attr prefix, name, and get its content */
        prefix = xmlctx->prefix;
        prefix_len = xmlctx->prefix_len;
        name = xmlctx->name;
        name_len = xmlctx->name_len;
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
        assert(xmlctx->status == LYXML_ATTR_CONTENT);

        /* handle special "xml" attribute prefix */
        if ((prefix_len == 3) && !strncmp(prefix, "xml", 3)) {
            name = prefix;
            name_len += 1 + prefix_len;
            prefix = NULL;
            prefix_len = 0;
        }

        /* find namespace of the attribute, if any */
        ns = NULL;
        if (prefix_len) {
            ns = lyxml_ns_get(&xmlctx->ns, prefix, prefix_len);
            if (!ns) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)prefix_len, prefix);
                ret = LY_EVALID;
                goto cleanup;
            }
        }

        /* get value prefixes */
        val_prefix_data = NULL;
        LY_CHECK_GOTO(ret = ly_store_prefix_data(xmlctx->ctx, xmlctx->value, xmlctx->value_len, LY_VALUE_XML,
                &xmlctx->ns, &format, &val_prefix_data), cleanup);

        /* attr2 is always changed to the created attribute */
        ret = lyd_create_attr(NULL, &attr2, xmlctx->ctx, name, name_len, prefix, prefix_len, ns ? ns->uri : NULL,
                ns ? strlen(ns->uri) : 0, xmlctx->value, xmlctx->value_len, &xmlctx->dynamic, format, val_prefix_data,
                LYD_HINT_DATA);
        LY_CHECK_GOTO(ret, cleanup);

        if (!*attr) {
            *attr = attr2;
        }

        /* next attribute */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
    }

cleanup:
    if (ret) {
        lyd_free_attr_siblings(xmlctx->ctx, *attr);
        *attr = NULL;
    }
    return ret;
}

static LY_ERR
lydxml_check_list(struct lyxml_ctx *xmlctx, const struct lysc_node *list)
{
    LY_ERR ret = LY_SUCCESS, r;
    enum LYXML_PARSER_STATUS next;
    struct ly_set key_set = {0};
    const struct lysc_node *snode;
    uint32_t i, parents_count;

    assert(list && (list->nodetype == LYS_LIST));

    /* get all keys into a set (keys do not have if-features or anything) */
    snode = NULL;
    while ((snode = lys_getnext(snode, list, NULL, 0)) && (snode->flags & LYS_KEY)) {
        ret = ly_set_add(&key_set, (void *)snode, 1, NULL);
        LY_CHECK_GOTO(ret, cleanup);
    }

    /* remember parent count */
    parents_count = xmlctx->elements.count;

    while (xmlctx->status == LYXML_ELEMENT) {
        /* find key definition */
        for (i = 0; i < key_set.count; ++i) {
            snode = (const struct lysc_node *)key_set.objs[i];
            if (!ly_strncmp(snode->name, xmlctx->name, xmlctx->name_len)) {
                break;
            }
        }
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);

        /* skip attributes */
        while (xmlctx->status == LYXML_ATTRIBUTE) {
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            assert(xmlctx->status == LYXML_ATTR_CONTENT);
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
        }

        assert(xmlctx->status == LYXML_ELEM_CONTENT);
        if (i < key_set.count) {
            /* validate the value */
            r = lys_value_validate(NULL, snode, xmlctx->value, xmlctx->value_len, LY_VALUE_XML, &xmlctx->ns);
            if (!r) {
                /* key with a valid value, remove from the set */
                ly_set_rm_index(&key_set, i, NULL);
            }
        }

        /* parser next */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);

        /* skip any children, resursively */
        while (xmlctx->status == LYXML_ELEMENT) {
            while (parents_count < xmlctx->elements.count) {
                LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
            }
            assert(xmlctx->status == LYXML_ELEM_CLOSE);
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
        }

        /* parser next, but do not parse closing element of the list because it would remove its namespaces */
        assert(xmlctx->status == LYXML_ELEM_CLOSE);
        LY_CHECK_GOTO(ret = lyxml_ctx_peek(xmlctx, &next), cleanup);
        if (next != LYXML_ELEM_CLOSE) {
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), cleanup);
        }
    }

    if (key_set.count) {
        /* some keys are missing/did not validate */
        ret = LY_ENOT;
    }

cleanup:
    ly_set_erase(&key_set, NULL);
    return ret;
}

/**
 * @brief Skip an element with all its descendants.
 *
 * @param[in] xmlctx XML parser context.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_data_skip(struct lyxml_ctx *xmlctx)
{
    uint32_t parents_count;

    /* remember current number of parents */
    parents_count = xmlctx->elements.count;
    assert(parents_count);

    /* skip after the content */
    while (xmlctx->status != LYXML_ELEM_CONTENT) {
        LY_CHECK_RET(lyxml_ctx_next(xmlctx));
    }
    LY_CHECK_RET(lyxml_ctx_next(xmlctx));

    /* skip all children elements, recursively, if any */
    while (parents_count <= xmlctx->elements.count) {
        LY_CHECK_RET(lyxml_ctx_next(xmlctx));
    }

    /* close element */
    assert(xmlctx->status == LYXML_ELEM_CLOSE);
    LY_CHECK_RET(lyxml_ctx_next(xmlctx));

    return LY_SUCCESS;
}

/**
 * @brief Check that the current element can be parsed as a data node.
 *
 * @param[in] lydctx XML data parser context.
 * @param[in,out] snode Found schema node, set to NULL if data node cannot be created.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_data_check_opaq(struct lyd_xml_ctx *lydctx, const struct lysc_node **snode)
{
    LY_ERR ret = LY_SUCCESS;
    struct lyxml_ctx *xmlctx = lydctx->xmlctx, pxmlctx;

    if (!(lydctx->parse_opts & LYD_PARSE_OPAQ)) {
        /* only checks specific to opaque nodes */
        return LY_SUCCESS;
    }

    if (!((*snode)->nodetype & (LYD_NODE_TERM | LYD_NODE_INNER))) {
        /* nothing to check */
        return LY_SUCCESS;
    }

    assert(xmlctx->elements.count);

    /* backup parser */
    LY_CHECK_RET(lyxml_ctx_backup(xmlctx, &pxmlctx));

    /* skip attributes */
    while (xmlctx->status == LYXML_ATTRIBUTE) {
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), restore);
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), restore);
    }

    if ((*snode)->nodetype & LYD_NODE_TERM) {
        /* value may not be valid in which case we parse it as an opaque node */
        if (lys_value_validate(NULL, *snode, xmlctx->value, xmlctx->value_len, LY_VALUE_XML, &xmlctx->ns)) {
            LOGVRB("Parsing opaque term node \"%s\" with invalid value \"%.*s\".", (*snode)->name, xmlctx->value_len,
                    xmlctx->value);
            *snode = NULL;
        }
    } else if ((*snode)->nodetype == LYS_LIST) {
        /* skip content */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), restore);

        if (lydxml_check_list(xmlctx, *snode)) {
            /* invalid list, parse as opaque if it missing/has invalid some keys */
            LOGVRB("Parsing opaque list node \"%s\" with missing/invalid keys.", (*snode)->name);
            *snode = NULL;
        }
    } else {
        /* if there is a non-WS value, it cannot be parsed as an inner node */
        assert(xmlctx->status == LYXML_ELEM_CONTENT);
        if (!xmlctx->ws_only) {
            *snode = NULL;
        }
    }

restore:
    /* restore parser */
    lyxml_ctx_restore(xmlctx, &pxmlctx);
    return ret;
}

/**
 * @brief Try to parse data with a parent based on an extension instance.
 *
 * @param[in] lydctx XML data parser context.
 * @param[in,out] parent Parent node where the children are inserted.
 * @return LY_SUCCESS on success;
 * @return LY_ENOT if no extension instance parsed the data;
 * @return LY_ERR on error.
 */
static LY_ERR
lydxml_nested_ext(struct lyd_xml_ctx *lydctx, struct lyd_node *parent)
{
    LY_ERR r;
    struct ly_in in_bck, in_start, in_ext;
    LY_ARRAY_COUNT_TYPE u;
    struct lysc_ext_instance *nested_exts = NULL;
    lyplg_ext_data_parse_clb ext_parse_cb;
    struct lyd_ctx_ext_val *ext_val;

    /* backup current input */
    in_bck = *lydctx->xmlctx->in;

    /* go back in the input for extension parsing */
    in_start = *lydctx->xmlctx->in;
    if (lydctx->xmlctx->status != LYXML_ELEM_CONTENT) {
        assert((lydctx->xmlctx->status == LYXML_ELEMENT) || (lydctx->xmlctx->status == LYXML_ATTRIBUTE));
        in_start.current = lydctx->xmlctx->prefix ? lydctx->xmlctx->prefix : lydctx->xmlctx->name;
    }
    do {
        --in_start.current;
    } while (in_start.current[0] != '<');

    /* check if there are any nested extension instances */
    if (parent && parent->schema) {
        nested_exts = parent->schema->exts;
    }
    LY_ARRAY_FOR(nested_exts, u) {
        /* prepare the input and try to parse this extension data */
        in_ext = in_start;
        ext_parse_cb = nested_exts[u].def->plugin->parse;
        r = ext_parse_cb(&in_ext, LYD_XML, &nested_exts[u], parent, lydctx->parse_opts | LYD_PARSE_ONLY);
        if (!r) {
            /* data successfully parsed, remember for validation */
            if (!(lydctx->parse_opts & LYD_PARSE_ONLY)) {
                ext_val = malloc(sizeof *ext_val);
                LY_CHECK_ERR_RET(!ext_val, LOGMEM(lydctx->xmlctx->ctx), LY_EMEM);
                ext_val->ext = &nested_exts[u];
                ext_val->sibling = lyd_child_no_keys(parent);
                LY_CHECK_RET(ly_set_add(&lydctx->ext_val, ext_val, 1, NULL));
            }

            /* adjust the xmlctx accordingly */
            *lydctx->xmlctx->in = in_ext;
            lydctx->xmlctx->status = LYXML_ELEM_CONTENT;
            lydctx->xmlctx->dynamic = 0;
            ly_set_rm_index(&lydctx->xmlctx->elements, lydctx->xmlctx->elements.count - 1, free);
            lyxml_ns_rm(lydctx->xmlctx);
            LY_CHECK_RET(lyxml_ctx_next(lydctx->xmlctx));
            return LY_SUCCESS;
        } else if (r != LY_ENOT) {
            /* fatal error */
            return r;
        }
        /* data was not from this module, continue */
    }

    /* no extensions or none matched, restore input */
    *lydctx->xmlctx->in = in_bck;
    return LY_ENOT;
}

/**
 * @brief Parse XML subtree.
 *
 * @param[in] lydctx XML YANG data parser context.
 * @param[in,out] parent Parent node where the children are inserted. NULL in case of parsing top-level elements.
 * @param[in,out] first_p Pointer to the first (@p parent or top-level) child. In case there were already some siblings,
 * this may point to a previously existing node.
 * @param[in,out] parsed Optional set to add all the parsed siblings into.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_subtree_r(struct lyd_xml_ctx *lydctx, struct lyd_node *parent, struct lyd_node **first_p, struct ly_set *parsed)
{
    LY_ERR ret = LY_SUCCESS, r;
    const char *prefix, *name, *val;
    size_t prefix_len, name_len;
    struct lyxml_ctx *xmlctx;
    const struct ly_ctx *ctx;
    const struct lyxml_ns *ns;
    struct lyd_meta *meta = NULL;
    struct lyd_attr *attr = NULL;
    const struct lysc_node *snode;
    struct lys_module *mod;
    uint32_t prev_parse_opts, prev_int_opts;
    struct lyd_node *node = NULL, *anchor;
    void *val_prefix_data = NULL;
    LY_VALUE_FORMAT format;
    uint32_t getnext_opts;
    ly_bool parse_subtree;

    assert(parent || first_p);

    xmlctx = lydctx->xmlctx;
    ctx = xmlctx->ctx;
    getnext_opts = lydctx->int_opts & LYD_INTOPT_REPLY ? LYS_GETNEXT_OUTPUT : 0;

    parse_subtree = lydctx->parse_opts & LYD_PARSE_SUBTREE ? 1 : 0;
    /* all descendants should be parsed */
    lydctx->parse_opts &= ~LYD_PARSE_SUBTREE;

    assert(xmlctx->status == LYXML_ELEMENT);

    /* remember element prefix and name */
    prefix = xmlctx->prefix;
    prefix_len = xmlctx->prefix_len;
    name = xmlctx->name;
    name_len = xmlctx->name_len;

    /* get the element module */
    ns = lyxml_ns_get(&xmlctx->ns, prefix, prefix_len);
    if (!ns) {
        LOGVAL(ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)prefix_len, prefix);
        ret = LY_EVALID;
        goto error;
    }
    mod = ly_ctx_get_module_implemented_ns(ctx, ns->uri);
    if (!mod) {
        /* check for extension data */
        r = lydxml_nested_ext(lydctx, parent);
        if (!r) {
            /* successfully parsed */
            return r;
        } else if (r != LY_ENOT) {
            /* error */
            ret = r;
            goto error;
        }

        /* unknown module */
        if (lydctx->parse_opts & LYD_PARSE_STRICT) {
            LOGVAL(ctx, LYVE_REFERENCE, "No module with namespace \"%s\" in the context.", ns->uri);
            ret = LY_EVALID;
            goto error;
        }
        if (!(lydctx->parse_opts & LYD_PARSE_OPAQ)) {
            /* skip element with children */
            LY_CHECK_GOTO(ret = lydxml_data_skip(xmlctx), error);
            return LY_SUCCESS;
        }
    }

    /* parser next */
    LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

    /* get the schema node */
    snode = NULL;
    if (mod) {
        if (!parent && lydctx->ext) {
            snode = lysc_ext_find_node(lydctx->ext, mod, name, name_len, 0, getnext_opts);
        } else {
            snode = lys_find_child(parent ? parent->schema : NULL, mod, name, name_len, 0, getnext_opts);
        }
        if (!snode) {
            /* check for extension data */
            r = lydxml_nested_ext(lydctx, parent);
            if (!r) {
                /* successfully parsed */
                return r;
            } else if (r != LY_ENOT) {
                /* error */
                ret = r;
                goto error;
            }

            /* unknown data node */
            if (lydctx->parse_opts & LYD_PARSE_STRICT) {
                if (parent) {
                    LOGVAL(ctx, LYVE_REFERENCE, "Node \"%.*s\" not found as a child of \"%s\" node.",
                            (int)name_len, name, LYD_NAME(parent));
                } else if (lydctx->ext) {
                    if (lydctx->ext->argument) {
                        LOGVAL(ctx, LYVE_REFERENCE, "Node \"%.*s\" not found in the \"%s\" %s extension instance.",
                                (int)name_len, name, lydctx->ext->argument, lydctx->ext->def->name);
                    } else {
                        LOGVAL(ctx, LYVE_REFERENCE, "Node \"%.*s\" not found in the %s extension instance.",
                                (int)name_len, name, lydctx->ext->def->name);
                    }
                } else {
                    LOGVAL(ctx, LYVE_REFERENCE, "Node \"%.*s\" not found in the \"%s\" module.",
                            (int)name_len, name, mod->name);
                }
                ret = LY_EVALID;
                goto error;
            } else if (!(lydctx->parse_opts & LYD_PARSE_OPAQ)) {
                LOGVRB("Skipping parsing of unknown node \"%.*s\".", name_len, name);

                /* skip element with children */
                LY_CHECK_GOTO(ret = lydxml_data_skip(xmlctx), error);
                return LY_SUCCESS;
            }
        } else {
            /* check that schema node is valid and can be used */
            LY_CHECK_GOTO(ret = lyd_parser_check_schema((struct lyd_ctx *)lydctx, snode), error);
            LY_CHECK_GOTO(ret = lydxml_data_check_opaq(lydctx, &snode), error);
        }
    }

    /* create metadata/attributes */
    if (xmlctx->status == LYXML_ATTRIBUTE) {
        if (snode) {
            ret = lydxml_metadata(lydctx, snode, &meta);
            LY_CHECK_GOTO(ret, error);
        } else {
            assert(lydctx->parse_opts & LYD_PARSE_OPAQ);
            ret = lydxml_attrs(xmlctx, &attr);
            LY_CHECK_GOTO(ret, error);
        }
    }

    assert(xmlctx->status == LYXML_ELEM_CONTENT);
    if (!snode) {
        assert(lydctx->parse_opts & LYD_PARSE_OPAQ);

        if (xmlctx->ws_only) {
            /* ignore WS-only value */
            if (xmlctx->dynamic) {
                free((char *) xmlctx->value);
            }
            xmlctx->dynamic = 0;
            xmlctx->value = "";
            xmlctx->value_len = 0;
            format = LY_VALUE_XML;
        } else {
            /* get value prefixes */
            ret = ly_store_prefix_data(xmlctx->ctx, xmlctx->value, xmlctx->value_len, LY_VALUE_XML,
                    &xmlctx->ns, &format, &val_prefix_data);
            LY_CHECK_GOTO(ret, error);
        }

        /* get NS again, it may have been backed up and restored */
        ns = lyxml_ns_get(&xmlctx->ns, prefix, prefix_len);
        assert(ns);

        /* create node */
        ret = lyd_create_opaq(ctx, name, name_len, prefix, prefix_len, ns->uri, strlen(ns->uri), xmlctx->value,
                xmlctx->value_len, &xmlctx->dynamic, format, val_prefix_data, LYD_HINT_DATA, &node);
        LY_CHECK_GOTO(ret, error);

        /* parser next */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

        /* process children */
        while (xmlctx->status == LYXML_ELEMENT) {
            ret = lydxml_subtree_r(lydctx, node, lyd_node_child_p(node), NULL);
            LY_CHECK_GOTO(ret, error);
        }
    } else if (snode->nodetype & LYD_NODE_TERM) {
        /* create node */
        LY_CHECK_GOTO(ret = lyd_parser_create_term((struct lyd_ctx *)lydctx, snode, xmlctx->value, xmlctx->value_len,
                &xmlctx->dynamic, LY_VALUE_XML, &xmlctx->ns, LYD_HINT_DATA, &node), error);
        LOG_LOCSET(snode, node, NULL, NULL);

        if (parent && (node->schema->flags & LYS_KEY)) {
            /* check the key order, the anchor must never be a key */
            anchor = lyd_insert_get_next_anchor(lyd_child(parent), node);
            if (anchor && (anchor->schema->flags & LYS_KEY)) {
                if (lydctx->parse_opts & LYD_PARSE_STRICT) {
                    LOGVAL(ctx, LYVE_DATA, "Invalid position of the key \"%s\" in a list.", node->schema->name);
                    ret = LY_EVALID;
                    goto error;
                } else {
                    LOGWRN(ctx, "Invalid position of the key \"%s\" in a list.", node->schema->name);
                }
            }
        }

        /* parser next */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

        /* no children expected */
        if (xmlctx->status == LYXML_ELEMENT) {
            LOGVAL(ctx, LYVE_SYNTAX, "Child element \"%.*s\" inside a terminal node \"%s\" found.",
                    (int)xmlctx->name_len, xmlctx->name, snode->name);
            ret = LY_EVALID;
            goto error;
        }
    } else if (snode->nodetype & LYD_NODE_INNER) {
        if (!xmlctx->ws_only) {
            /* value in inner node */
            LOGVAL(ctx, LYVE_SYNTAX, "Text value \"%.*s\" inside an inner node \"%s\" found.",
                    (int)xmlctx->value_len, xmlctx->value, snode->name);
            ret = LY_EVALID;
            goto error;
        }

        /* create node */
        ret = lyd_create_inner(snode, &node);
        LY_CHECK_GOTO(ret, error);

        LOG_LOCSET(snode, node, NULL, NULL);

        /* parser next */
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

        /* process children */
        while (xmlctx->status == LYXML_ELEMENT) {
            ret = lydxml_subtree_r(lydctx, node, lyd_node_child_p(node), NULL);
            LY_CHECK_GOTO(ret, error);
        }

        if (snode->nodetype == LYS_LIST) {
            /* check all keys exist */
            LY_CHECK_GOTO(ret = lyd_parse_check_keys(node), error);
        }

        if (!(lydctx->parse_opts & LYD_PARSE_ONLY)) {
            /* new node validation, autodelete CANNOT occur, all nodes are new */
            ret = lyd_validate_new(lyd_node_child_p(node), snode, NULL, NULL);
            LY_CHECK_GOTO(ret, error);

            /* add any missing default children */
            ret = lyd_new_implicit_r(node, lyd_node_child_p(node), NULL, NULL, &lydctx->node_when, &lydctx->node_types,
                    (lydctx->val_opts & LYD_VALIDATE_NO_STATE) ? LYD_IMPLICIT_NO_STATE : 0, NULL);
            LY_CHECK_GOTO(ret, error);
        }

        if (snode->nodetype & (LYS_RPC | LYS_ACTION | LYS_NOTIF)) {
            /* rememeber the RPC/action/notification */
            lydctx->op_node = node;
        }
    } else if (snode->nodetype & LYD_NODE_ANY) {
        if ((snode->nodetype == LYS_ANYDATA) && !xmlctx->ws_only) {
            /* value in anydata node, we expect a tree */
            LOGVAL(ctx, LYVE_SYNTAX, "Text value \"%.*s\" inside an anydata node \"%s\" found.",
                    (int)xmlctx->value_len < 20 ? xmlctx->value_len : 20, xmlctx->value, snode->name);
            ret = LY_EVALID;
            goto error;
        }

        if (!xmlctx->ws_only) {
            /* use an arbitrary text value for anyxml */
            lydict_insert(xmlctx->ctx, xmlctx->value, xmlctx->value_len, &val);

            /* parser next */
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

            /* create node */
            ret = lyd_create_any(snode, val, LYD_ANYDATA_STRING, 1, &node);
            LY_CHECK_GOTO(ret, error);
        } else {
            /* parser next */
            LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);

            /* update options so that generic data can be parsed */
            prev_parse_opts = lydctx->parse_opts;
            lydctx->parse_opts &= ~LYD_PARSE_STRICT;
            lydctx->parse_opts |= LYD_PARSE_OPAQ;
            prev_int_opts = lydctx->int_opts;
            lydctx->int_opts |= LYD_INTOPT_ANY | LYD_INTOPT_WITH_SIBLINGS;

            /* parse any data tree */
            anchor = NULL;
            while (xmlctx->status == LYXML_ELEMENT) {
                ret = lydxml_subtree_r(lydctx, NULL, &anchor, NULL);
                if (ret) {
                    break;
                }
            }

            /* restore options */
            lydctx->parse_opts = prev_parse_opts;
            lydctx->int_opts = prev_int_opts;

            LY_CHECK_GOTO(ret, error);

            /* create node */
            ret = lyd_create_any(snode, anchor, LYD_ANYDATA_DATATREE, 1, &node);
            LY_CHECK_GOTO(ret, error);
        }
    }
    assert(node);

    /* add/correct flags */
    if (snode) {
        lyd_parse_set_data_flags(node, &lydctx->node_when, &meta, lydctx->parse_opts);
    }

    /* parser next */
    assert(xmlctx->status == LYXML_ELEM_CLOSE);
    if (!parse_subtree) {
        LY_CHECK_GOTO(ret = lyxml_ctx_next(xmlctx), error);
    }

    /* add metadata/attributes */
    if (snode) {
        lyd_insert_meta(node, meta, 0);
    } else {
        lyd_insert_attr(node, attr);
    }

    /* insert, keep first pointer correct */
    lyd_insert_node(parent, first_p, node, lydctx->parse_opts & LYD_PARSE_ORDERED ? 1 : 0);
    while (!parent && (*first_p)->prev->next) {
        *first_p = (*first_p)->prev;
    }

    /* rememeber a successfully parsed node */
    if (parsed) {
        ly_set_add(parsed, node, 1, NULL);
    }

    LOG_LOCBACK(node ? 1 : 0, node ? 1 : 0, 0, 0);
    return LY_SUCCESS;

error:
    LOG_LOCBACK(node ? 1 : 0, node ? 1 : 0, 0, 0);
    lyd_free_meta_siblings(meta);
    lyd_free_attr_siblings(ctx, attr);
    lyd_free_tree(node);
    return ret;
}

/**
 * @brief Parse a specific XML element into an opaque node.
 *
 * @param[in] xmlctx XML parser context.
 * @param[in] name Name of the element.
 * @param[in] uri URI of the element.
 * @param[in] value Whether a value is expected in the element.
 * @param[out] evnp Parsed envelope (opaque node).
 * @return LY_SUCCESS on success.
 * @return LY_ENOT if the specified element did not match.
 * @return LY_ERR value on error.
 */
static LY_ERR
lydxml_envelope(struct lyxml_ctx *xmlctx, const char *name, const char *uri, ly_bool value, struct lyd_node **envp)
{
    LY_ERR rc = LY_SUCCESS;
    const struct lyxml_ns *ns;
    struct lyd_attr *attr = NULL;
    const char *prefix;
    size_t prefix_len;

    assert(xmlctx->status == LYXML_ELEMENT);
    if (ly_strncmp(name, xmlctx->name, xmlctx->name_len)) {
        /* not the expected element */
        return LY_ENOT;
    }

    prefix = xmlctx->prefix;
    prefix_len = xmlctx->prefix_len;
    ns = lyxml_ns_get(&xmlctx->ns, prefix, prefix_len);
    if (!ns) {
        LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)prefix_len, prefix);
        return LY_EVALID;
    } else if (strcmp(ns->uri, uri)) {
        /* different namespace */
        return LY_ENOT;
    }

    LY_CHECK_RET(lyxml_ctx_next(xmlctx));

    /* create attributes */
    if (xmlctx->status == LYXML_ATTRIBUTE) {
        LY_CHECK_RET(lydxml_attrs(xmlctx, &attr));
    }

    assert(xmlctx->status == LYXML_ELEM_CONTENT);
    if (!value && !xmlctx->ws_only) {
        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected value \"%.*s\" in the \"%s\" element.",
                (int)xmlctx->value_len, xmlctx->value, name);
        rc = LY_EVALID;
        goto cleanup;
    }

    /* create node */
    rc = lyd_create_opaq(xmlctx->ctx, name, strlen(name), prefix, prefix_len, uri, strlen(uri), xmlctx->value,
            xmlctx->ws_only ? 0 : xmlctx->value_len, NULL, LY_VALUE_XML, NULL, 0, envp);
    LY_CHECK_GOTO(rc, cleanup);

    /* assign atributes */
    ((struct lyd_node_opaq *)(*envp))->attr = attr;
    attr = NULL;

    /* parser next element */
    LY_CHECK_GOTO(rc = lyxml_ctx_next(xmlctx), cleanup);

cleanup:
    lyd_free_attr_siblings(xmlctx->ctx, attr);
    if (rc) {
        lyd_free_tree(*envp);
        *envp = NULL;
    }
    return rc;
}

/**
 * @brief Parse all expected non-data XML elements of a NETCONF rpc message.
 *
 * @param[in] xmlctx XML parser context.
 * @param[out] evnp Parsed envelope(s) (opaque node).
 * @param[out] int_opts Internal options for parsing the rest of YANG data.
 * @param[out] close_elem Number of parsed opened elements that need to be closed.
 * @return LY_SUCCESS on success.
 * @return LY_ERR value on error.
 */
static LY_ERR
lydxml_env_netconf_rpc(struct lyxml_ctx *xmlctx, struct lyd_node **envp, uint32_t *int_opts, uint32_t *close_elem)
{
    LY_ERR rc = LY_SUCCESS, r;
    struct lyd_node *child;

    assert(envp && !*envp);

    /* parse "rpc" */
    r = lydxml_envelope(xmlctx, "rpc", "urn:ietf:params:xml:ns:netconf:base:1.0", 0, envp);
    LY_CHECK_ERR_GOTO(r, rc = r, cleanup);

    /* parse "action", if any */
    r = lydxml_envelope(xmlctx, "action", "urn:ietf:params:xml:ns:yang:1", 0, &child);
    if (r == LY_SUCCESS) {
        /* insert */
        lyd_insert_node(*envp, NULL, child, 0);

        /* NETCONF action */
        *int_opts = LYD_INTOPT_NO_SIBLINGS | LYD_INTOPT_ACTION;
        *close_elem = 2;
    } else if (r == LY_ENOT) {
        /* NETCONF RPC */
        *int_opts = LYD_INTOPT_NO_SIBLINGS | LYD_INTOPT_RPC;
        *close_elem = 1;
    } else {
        rc = r;
        goto cleanup;
    }

cleanup:
    if (rc) {
        lyd_free_tree(*envp);
        *envp = NULL;
    }
    return rc;
}

/**
 * @brief Parse all expected non-data XML elements of a NETCONF notification message.
 *
 * @param[in] xmlctx XML parser context.
 * @param[out] evnp Parsed envelope(s) (opaque node).
 * @param[out] int_opts Internal options for parsing the rest of YANG data.
 * @param[out] close_elem Number of parsed opened elements that need to be closed.
 * @return LY_SUCCESS on success.
 * @return LY_ERR value on error.
 */
static LY_ERR
lydxml_env_netconf_notif(struct lyxml_ctx *xmlctx, struct lyd_node **envp, uint32_t *int_opts, uint32_t *close_elem)
{
    LY_ERR rc = LY_SUCCESS, r;
    struct lyd_node *child;

    assert(envp && !*envp);

    /* parse "notification" */
    r = lydxml_envelope(xmlctx, "notification", "urn:ietf:params:xml:ns:netconf:notification:1.0", 0, envp);
    LY_CHECK_ERR_GOTO(r, rc = r, cleanup);

    /* parse "eventTime" */
    r = lydxml_envelope(xmlctx, "eventTime", "urn:ietf:params:xml:ns:netconf:notification:1.0", 1, &child);
    if (r == LY_ENOT) {
        LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unexpected element \"%.*s\" instead of \"eventTime\".",
                (int)xmlctx->name_len, xmlctx->name);
        r = LY_EVALID;
    }
    LY_CHECK_ERR_GOTO(r, rc = r, cleanup);

    /* insert */
    lyd_insert_node(*envp, NULL, child, 0);

    /* validate value */
    /* TODO validate child->value as yang:date-and-time */

    /* finish child parsing */
    if (xmlctx->status != LYXML_ELEM_CLOSE) {
        assert(xmlctx->status == LYXML_ELEMENT);
        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"eventTime\".",
                (int)xmlctx->name_len, xmlctx->name);
        rc = LY_EVALID;
        goto cleanup;
    }
    LY_CHECK_GOTO(rc = lyxml_ctx_next(xmlctx), cleanup);

    /* NETCONF notification */
    *int_opts = LYD_INTOPT_NO_SIBLINGS | LYD_INTOPT_NOTIF;
    *close_elem = 1;

cleanup:
    if (rc) {
        lyd_free_tree(*envp);
        *envp = NULL;
    }
    return rc;
}

/**
 * @brief Parse an XML element as an opaque node subtree.
 *
 * @param[in] xmlctx XML parser context.
 * @param[in] parent Parent to append nodes to.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_opaq_r(struct lyxml_ctx *xmlctx, struct lyd_node *parent)
{
    LY_ERR rc = LY_SUCCESS;
    const struct lyxml_ns *ns;
    struct lyd_attr *attr = NULL;
    struct lyd_node *child = NULL;
    const char *name, *prefix;
    size_t name_len, prefix_len;

    assert(xmlctx->status == LYXML_ELEMENT);

    name = xmlctx->name;
    name_len = xmlctx->name_len;
    prefix = xmlctx->prefix;
    prefix_len = xmlctx->prefix_len;
    ns = lyxml_ns_get(&xmlctx->ns, prefix, prefix_len);
    if (!ns) {
        LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)prefix_len, prefix);
        return LY_EVALID;
    }

    LY_CHECK_RET(lyxml_ctx_next(xmlctx));

    /* create attributes */
    if (xmlctx->status == LYXML_ATTRIBUTE) {
        LY_CHECK_RET(lydxml_attrs(xmlctx, &attr));
    }

    /* create node */
    assert(xmlctx->status == LYXML_ELEM_CONTENT);
    rc = lyd_create_opaq(xmlctx->ctx, name, name_len, prefix, prefix_len, ns->uri, strlen(ns->uri), xmlctx->value,
            xmlctx->ws_only ? 0 : xmlctx->value_len, NULL, LY_VALUE_XML, NULL, 0, &child);
    LY_CHECK_GOTO(rc, cleanup);

    /* assign atributes */
    ((struct lyd_node_opaq *)child)->attr = attr;
    attr = NULL;

    /* parser next element */
    LY_CHECK_GOTO(rc = lyxml_ctx_next(xmlctx), cleanup);

    /* parse all the descendants */
    while (xmlctx->status == LYXML_ELEMENT) {
        rc = lydxml_opaq_r(xmlctx, child);
        LY_CHECK_GOTO(rc, cleanup);
    }

    /* insert */
    lyd_insert_node(parent, NULL, child, 1);

cleanup:
    lyd_free_attr_siblings(xmlctx->ctx, attr);
    if (rc) {
        lyd_free_tree(child);
    }
    return rc;
}

/**
 * @brief Parse all expected non-data XML elements of the error-info element in NETCONF rpc-reply message.
 *
 * @param[in] xmlctx XML parser context.
 * @param[in] parent Parent to append nodes to.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_env_netconf_rpc_reply_error_info(struct lyxml_ctx *xmlctx, struct lyd_node *parent)
{
    LY_ERR r;
    struct lyd_node *child, *iter;
    const struct lyxml_ns *ns;
    ly_bool no_dup;

    /* there must be some child */
    if (xmlctx->status == LYXML_ELEM_CLOSE) {
        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Missing child elements of \"error-info\".");
        return LY_EVALID;
    }

    while (xmlctx->status == LYXML_ELEMENT) {
        child = NULL;

        /*
         * session-id
         */
        r = lydxml_envelope(xmlctx, "session-id", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * bad-attribute
         */
        r = lydxml_envelope(xmlctx, "bad-attribute", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * bad-element
         */
        r = lydxml_envelope(xmlctx, "bad-element", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * bad-namespace
         */
        r = lydxml_envelope(xmlctx, "bad-namespace", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        if (r == LY_ENOT) {
            assert(xmlctx->status == LYXML_ELEMENT);

            /* learn namespace */
            ns = lyxml_ns_get(&xmlctx->ns, xmlctx->prefix, xmlctx->prefix_len);
            if (!ns) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Unknown XML prefix \"%.*s\".", (int)xmlctx->prefix_len, xmlctx->prefix);
                r = LY_EVALID;
                goto error;
            } else if (!strcmp(ns->uri, "urn:ietf:params:xml:ns:netconf:base:1.0")) {
                LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"error-info\".",
                        (int)xmlctx->name_len, xmlctx->name);
                r = LY_EVALID;
                goto error;
            }

            /* custom elements */
            r = lydxml_opaq_r(xmlctx, parent);
            LY_CHECK_GOTO(r, error);
            continue;
        }

check_child:
        /* check for duplicates */
        if (no_dup) {
            LY_LIST_FOR(lyd_child(parent), iter) {
                if ((((struct lyd_node_opaq *)iter)->name.name == ((struct lyd_node_opaq *)child)->name.name) &&
                        (((struct lyd_node_opaq *)iter)->name.module_ns == ((struct lyd_node_opaq *)child)->name.module_ns)) {
                    LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Duplicate element \"%s\" in \"error-info\".",
                            ((struct lyd_node_opaq *)child)->name.name);
                    r = LY_EVALID;
                    goto error;
                }
            }
        }

        /* finish child parsing */
        if (xmlctx->status != LYXML_ELEM_CLOSE) {
            assert(xmlctx->status == LYXML_ELEMENT);
            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"error-info\".",
                    (int)xmlctx->name_len, xmlctx->name);
            r = LY_EVALID;
            goto error;
        }
        LY_CHECK_GOTO(r = lyxml_ctx_next(xmlctx), error);

        /* insert */
        lyd_insert_node(parent, NULL, child, 1);
    }

    return LY_SUCCESS;

error:
    lyd_free_tree(child);
    return r;
}

/**
 * @brief Parse all expected non-data XML elements of the rpc-error element in NETCONF rpc-reply message.
 *
 * @param[in] xmlctx XML parser context.
 * @param[in] parent Parent to append nodes to.
 * @return LY_ERR value.
 */
static LY_ERR
lydxml_env_netconf_rpc_reply_error(struct lyxml_ctx *xmlctx, struct lyd_node *parent)
{
    LY_ERR r;
    struct lyd_node *child, *iter;
    const char *val;
    ly_bool no_dup;

    /* there must be some child */
    if (xmlctx->status == LYXML_ELEM_CLOSE) {
        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Missing child elements of \"rpc-error\".");
        return LY_EVALID;
    }

    while (xmlctx->status == LYXML_ELEMENT) {
        child = NULL;

        /*
         * error-type
         */
        r = lydxml_envelope(xmlctx, "error-type", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            val = ((struct lyd_node_opaq *)child)->value;
            if (strcmp(val, "transport") && strcmp(val, "rpc") && strcmp(val, "protocol") && strcmp(val, "application")) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Invalid value \"%s\" of element \"%s\".", val,
                        ((struct lyd_node_opaq *)child)->name.name);
                r = LY_EVALID;
                goto error;
            }

            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * error-tag
         */
        r = lydxml_envelope(xmlctx, "error-tag", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            val = ((struct lyd_node_opaq *)child)->value;
            if (strcmp(val, "in-use") && strcmp(val, "invalid-value") && strcmp(val, "too-big") &&
                    strcmp(val, "missing-attribute") && strcmp(val, "bad-attribute") &&
                    strcmp(val, "unknown-attribute") && strcmp(val, "missing-element") && strcmp(val, "bad-element") &&
                    strcmp(val, "unknown-element") && strcmp(val, "unknown-namespace") && strcmp(val, "access-denied") &&
                    strcmp(val, "lock-denied") && strcmp(val, "resource-denied") && strcmp(val, "rollback-failed") &&
                    strcmp(val, "data-exists") && strcmp(val, "data-missing") && strcmp(val, "operation-not-supported") &&
                    strcmp(val, "operation-failed") && strcmp(val, "malformed-message")) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Invalid value \"%s\" of element \"%s\".", val,
                        ((struct lyd_node_opaq *)child)->name.name);
                r = LY_EVALID;
                goto error;
            }

            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * error-severity
         */
        r = lydxml_envelope(xmlctx, "error-severity", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            val = ((struct lyd_node_opaq *)child)->value;
            if (strcmp(val, "error") && strcmp(val, "warning")) {
                LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Invalid value \"%s\" of element \"%s\".", val,
                        ((struct lyd_node_opaq *)child)->name.name);
                r = LY_EVALID;
                goto error;
            }

            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * error-app-tag
         */
        r = lydxml_envelope(xmlctx, "error-app-tag", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * error-path
         */
        r = lydxml_envelope(xmlctx, "error-path", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /*
         * error-message
         */
        r = lydxml_envelope(xmlctx, "error-message", "urn:ietf:params:xml:ns:netconf:base:1.0", 1, &child);
        if (r == LY_SUCCESS) {
            no_dup = 1;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        /* error-info */
        r = lydxml_envelope(xmlctx, "error-info", "urn:ietf:params:xml:ns:netconf:base:1.0", 0, &child);
        if (r == LY_SUCCESS) {
            /* parse all the descendants */
            LY_CHECK_GOTO(r = lydxml_env_netconf_rpc_reply_error_info(xmlctx, child), error);

            no_dup = 0;
            goto check_child;
        } else if (r != LY_ENOT) {
            goto error;
        }

        if (r == LY_ENOT) {
            assert(xmlctx->status == LYXML_ELEMENT);
            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"rpc-error\".",
                    (int)xmlctx->name_len, xmlctx->name);
            r = LY_EVALID;
            goto error;
        }

check_child:
        /* check for duplicates */
        if (no_dup) {
            LY_LIST_FOR(lyd_child(parent), iter) {
                if ((((struct lyd_node_opaq *)iter)->name.name == ((struct lyd_node_opaq *)child)->name.name) &&
                        (((struct lyd_node_opaq *)iter)->name.module_ns == ((struct lyd_node_opaq *)child)->name.module_ns)) {
                    LOGVAL(xmlctx->ctx, LYVE_REFERENCE, "Duplicate element \"%s\" in \"rpc-error\".",
                            ((struct lyd_node_opaq *)child)->name.name);
                    r = LY_EVALID;
                    goto error;
                }
            }
        }

        /* finish child parsing */
        if (xmlctx->status != LYXML_ELEM_CLOSE) {
            assert(xmlctx->status == LYXML_ELEMENT);
            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"rpc-error\".",
                    (int)xmlctx->name_len, xmlctx->name);
            r = LY_EVALID;
            goto error;
        }
        LY_CHECK_GOTO(r = lyxml_ctx_next(xmlctx), error);

        /* insert */
        lyd_insert_node(parent, NULL, child, 1);
    }

    return LY_SUCCESS;

error:
    lyd_free_tree(child);
    return r;
}

/**
 * @brief Parse all expected non-data XML elements of a NETCONF rpc-reply message.
 *
 * @param[in] xmlctx XML parser context.
 * @param[out] evnp Parsed envelope(s) (opaque node).
 * @param[out] int_opts Internal options for parsing the rest of YANG data.
 * @param[out] close_elem Number of parsed opened elements that need to be closed.
 * @return LY_SUCCESS on success.
 * @return LY_ERR value on error.
 */
static LY_ERR
lydxml_env_netconf_reply(struct lyxml_ctx *xmlctx, struct lyd_node **envp, uint32_t *int_opts, uint32_t *close_elem)
{
    LY_ERR rc = LY_SUCCESS, r;
    struct lyd_node *child = NULL;
    const char *parsed_elem = NULL;

    assert(envp && !*envp);

    /* parse "rpc-reply" */
    r = lydxml_envelope(xmlctx, "rpc-reply", "urn:ietf:params:xml:ns:netconf:base:1.0", 0, envp);
    LY_CHECK_ERR_GOTO(r, rc = r, cleanup);

    /* there must be some child */
    if (xmlctx->status == LYXML_ELEM_CLOSE) {
        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Missing child elements of \"rpc-reply\".");
        rc = LY_EVALID;
        goto cleanup;
    }

    /* try to parse "ok" */
    r = lydxml_envelope(xmlctx, "ok", "urn:ietf:params:xml:ns:netconf:base:1.0", 0, &child);
    if (r == LY_SUCCESS) {
        /* insert */
        lyd_insert_node(*envp, NULL, child, 1);

        /* finish child parsing */
        if (xmlctx->status != LYXML_ELEM_CLOSE) {
            assert(xmlctx->status == LYXML_ELEMENT);
            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\" of \"ok\".",
                    (int)xmlctx->name_len, xmlctx->name);
            rc = LY_EVALID;
            goto cleanup;
        }
        LY_CHECK_GOTO(rc = lyxml_ctx_next(xmlctx), cleanup);

        /* success */
        parsed_elem = "ok";
        goto finish;
    } else if (r != LY_ENOT) {
        rc = r;
        goto cleanup;
    }

    /* try to parse all "rpc-error" elements */
    while (xmlctx->status == LYXML_ELEMENT) {
        r = lydxml_envelope(xmlctx, "rpc-error", "urn:ietf:params:xml:ns:netconf:base:1.0", 0, &child);
        if (r == LY_ENOT) {
            break;
        } else if (r) {
            rc = r;
            goto cleanup;
        }

        /* insert */
        lyd_insert_node(*envp, NULL, child, 1);

        /* parse all children of "rpc-error" */
        LY_CHECK_GOTO(rc = lydxml_env_netconf_rpc_reply_error(xmlctx, child), cleanup);

        /* finish child parsing */
        assert(xmlctx->status == LYXML_ELEM_CLOSE);
        LY_CHECK_GOTO(rc = lyxml_ctx_next(xmlctx), cleanup);

        parsed_elem = "rpc-error";
    }

finish:
    if (parsed_elem) {
        /* NETCONF rpc-reply with no data */
        if (xmlctx->status != LYXML_ELEM_CLOSE) {
            assert(xmlctx->status == LYXML_ELEMENT);
            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Unexpected sibling element \"%.*s\" of \"%s\".",
                    (int)xmlctx->name_len, xmlctx->name, parsed_elem);
            rc = LY_EVALID;
            goto cleanup;
        }
    }

    /* NETCONF rpc-reply */
    *int_opts = LYD_INTOPT_WITH_SIBLINGS | LYD_INTOPT_REPLY;
    *close_elem = 1;

cleanup:
    if (rc) {
        lyd_free_tree(*envp);
        *envp = NULL;
    }
    return rc;
}

LY_ERR
lyd_parse_xml(const struct ly_ctx *ctx, const struct lysc_ext_instance *ext, struct lyd_node *parent,
        struct lyd_node **first_p, struct ly_in *in, uint32_t parse_opts, uint32_t val_opts, enum lyd_type data_type,
        struct lyd_node **envp, struct ly_set *parsed, ly_bool *subtree_sibling, struct lyd_ctx **lydctx_p)
{
    LY_ERR rc = LY_SUCCESS;
    struct lyd_xml_ctx *lydctx;
    uint32_t i, int_opts = 0, close_elem = 0;
    ly_bool parsed_data_nodes = 0;
    enum LYXML_PARSER_STATUS status;

    assert(ctx && in && lydctx_p);
    assert(!(parse_opts & ~LYD_PARSE_OPTS_MASK));
    assert(!(val_opts & ~LYD_VALIDATE_OPTS_MASK));

    /* init context */
    lydctx = calloc(1, sizeof *lydctx);
    LY_CHECK_ERR_RET(!lydctx, LOGMEM(ctx), LY_EMEM);
    LY_CHECK_GOTO(rc = lyxml_ctx_new(ctx, in, &lydctx->xmlctx), cleanup);
    lydctx->parse_opts = parse_opts;
    lydctx->val_opts = val_opts;
    lydctx->free = lyd_xml_ctx_free;
    lydctx->ext = ext;

    switch (data_type) {
    case LYD_TYPE_DATA_YANG:
        if (!(parse_opts & LYD_PARSE_SUBTREE)) {
            int_opts = LYD_INTOPT_WITH_SIBLINGS;
        }
        break;
    case LYD_TYPE_RPC_YANG:
        int_opts = LYD_INTOPT_RPC | LYD_INTOPT_ACTION | LYD_INTOPT_NO_SIBLINGS;
        break;
    case LYD_TYPE_NOTIF_YANG:
        int_opts = LYD_INTOPT_NOTIF | LYD_INTOPT_NO_SIBLINGS;
        break;
    case LYD_TYPE_REPLY_YANG:
        int_opts = LYD_INTOPT_REPLY | LYD_INTOPT_NO_SIBLINGS;
        break;
    case LYD_TYPE_RPC_NETCONF:
        assert(!parent);
        LY_CHECK_GOTO(rc = lydxml_env_netconf_rpc(lydctx->xmlctx, envp, &int_opts, &close_elem), cleanup);
        break;
    case LYD_TYPE_NOTIF_NETCONF:
        assert(!parent);
        LY_CHECK_GOTO(rc = lydxml_env_netconf_notif(lydctx->xmlctx, envp, &int_opts, &close_elem), cleanup);
        break;
    case LYD_TYPE_REPLY_NETCONF:
        assert(parent);
        LY_CHECK_GOTO(rc = lydxml_env_netconf_reply(lydctx->xmlctx, envp, &int_opts, &close_elem), cleanup);
        break;
    }
    lydctx->int_opts = int_opts;

    /* find the operation node if it exists already */
    LY_CHECK_GOTO(rc = lyd_parser_find_operation(parent, int_opts, &lydctx->op_node), cleanup);

    /* parse XML data */
    while (lydctx->xmlctx->status == LYXML_ELEMENT) {
        LY_CHECK_GOTO(rc = lydxml_subtree_r(lydctx, parent, first_p, parsed), cleanup);
        parsed_data_nodes = 1;

        if (!(int_opts & LYD_INTOPT_WITH_SIBLINGS)) {
            break;
        }
    }

    /* close all opened elements */
    for (i = 0; i < close_elem; ++i) {
        if (lydctx->xmlctx->status != LYXML_ELEM_CLOSE) {
            assert(lydctx->xmlctx->status == LYXML_ELEMENT);
            LOGVAL(lydctx->xmlctx->ctx, LYVE_SYNTAX, "Unexpected child element \"%.*s\".",
                    (int)lydctx->xmlctx->name_len, lydctx->xmlctx->name);
            rc = LY_EVALID;
            goto cleanup;
        }

        LY_CHECK_GOTO(rc = lyxml_ctx_next(lydctx->xmlctx), cleanup);
    }

    /* check final state */
    if ((int_opts & LYD_INTOPT_NO_SIBLINGS) && (lydctx->xmlctx->status == LYXML_ELEMENT)) {
        LOGVAL(ctx, LYVE_SYNTAX, "Unexpected sibling node.");
        rc = LY_EVALID;
        goto cleanup;
    }
    if ((int_opts & (LYD_INTOPT_RPC | LYD_INTOPT_ACTION | LYD_INTOPT_NOTIF | LYD_INTOPT_REPLY)) && !lydctx->op_node) {
        LOGVAL(ctx, LYVE_DATA, "Missing the operation node.");
        rc = LY_EVALID;
        goto cleanup;
    }

    if (!parsed_data_nodes) {
        /* no data nodes were parsed */
        lydctx->op_node = NULL;
    }

    if (parse_opts & LYD_PARSE_SUBTREE) {
        /* check for a sibling element */
        assert(subtree_sibling);
        if (!lyxml_ctx_peek(lydctx->xmlctx, &status) && (status == LYXML_ELEMENT)) {
            *subtree_sibling = 1;
        } else {
            *subtree_sibling = 0;
        }
    }

cleanup:
    /* there should be no unres stored if validation should be skipped */
    assert(!(parse_opts & LYD_PARSE_ONLY) || (!lydctx->node_types.count && !lydctx->meta_types.count &&
            !lydctx->node_when.count));

    if (rc) {
        lyd_xml_ctx_free((struct lyd_ctx *)lydctx);
    } else {
        *lydctx_p = (struct lyd_ctx *)lydctx;

        /* the XML context is no more needed, freeing it also stops logging line numbers which would be confusing now */
        lyxml_ctx_free(lydctx->xmlctx);
        lydctx->xmlctx = NULL;
    }
    return rc;
}