src/parser_json.c

/**
 * @file parser_json.c
 * @author Radek Krejci <rkrejci@cesnet.cz>
 * @brief JSON data parser for libyang
 *
 * Copyright (c) 2015 CESNET, z.s.p.o.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of the Company nor the names of its contributors
 *    may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 */

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include "libyang.h"
#include "common.h"
#include "context.h"
#include "parser.h"
#include "printer.h"
#include "tree_internal.h"
#include "validation.h"

#ifndef NDEBUG
static unsigned int lineno;
#endif

static int
lyjson_isspace(int c)
{
    switch(c) {
    case 0x20: /* space */
    case 0x09: /* horizontal tab */
    case 0x0a: /* line feed or new line */
    case 0x0d: /* carriage return */
        return 1;
    default:
        return 0;
    }
}

static unsigned int
skip_ws(const char *data)
{
    unsigned int len = 0;

    /* skip leading whitespaces */
    while (data[len] && lyjson_isspace(data[len])) {
        COUNTLINE(data[len]);
        len++;
    }

    return len;
}

int lyjson_dump_string(struct lyout *out, const char *text)
{
    unsigned int i, n;

    if (!text) {
        return 0;
    }

    ly_write(out, "\"", 1);
    for (i = n = 0; text[i]; i++) {
        if (text[i] < 0x20) {
            /* control character */
            n += ly_print(out, "\\u%.4X");
        } else {
            switch (text[i]) {
            case '"':
                n += ly_print(out, "\\\"");
                break;
            case '\\':
                n += ly_print(out, "\\\\");
                break;
            case '/':
                n += ly_print(out, "\\/");
                break;
            default:
                ly_write(out, &text[i], 1);
                n++;
            }
        }
    }
    ly_write(out, "\"", 1);

    return n + 2;
}


static char *
lyjson_parse_text(const char *data, unsigned int *len)
{
#define BUFSIZE 1024

    char buf[BUFSIZE];
    char *result = NULL, *aux;
    int o, size;
    unsigned int r, i;
    int32_t value;

    for (*len = o = 0; data[*len] && data[*len] != '"'; o++) {
        if (o > BUFSIZE - 3) {
            /* add buffer into the result */
            if (result) {
                size = size + o;
                aux = realloc(result, size + 1);
                result = aux;
            } else {
                size = o;
                result = malloc((size + 1) * sizeof *result);
            }
            memcpy(&result[size - o], buf, o);

            /* write again into the beginning of the buffer */
            o = 0;
        }

        if (data[*len] == '\\') {
            /* parse escape sequence */
            (*len)++;
            i = 1;
            switch (data[(*len)]) {
            case '"':
                /* quotation mark */
                value = 0x22;
                break;
            case '\\':
                /* reverse solidus */
                value = 0x5c;
                break;
            case '/':
                /* solidus */
                value = 0x2f;
                break;
            case 'b':
                /* backspace */
                value = 0x08;
                break;
            case 'f':
                /* form feed */
                value = 0x0c;
                break;
            case 'n':
                /* line feed */
                value = 0x0a;
                break;
            case 'r':
                /* carriage return */
                value = 0x0d;
                break;
            case 't':
                /* tab */
                value = 0x09;
                break;
            case 'u':
                /* Basic Multilingual Plane character \uXXXX */
                (*len)++;
                for (value = i = 0; i < 4; i++) {
                    if (isdigit(data[(*len) + i])) {
                        r = (data[(*len) + i] - '0');
                    } else if (data[(*len) + i] > 'F') {
                        r = 10 + (data[(*len) + i] - 'a');
                    } else {
                        r = 10 + (data[(*len) + i] - 'A');
                    }
                    value = (16 * value) + r;
                }
                break;
            default:
                /* invalid escape sequence */
                LOGVAL(LYE_XML_INVAL, lineno, "character escape sequence");
                goto error;

            }
            r = pututf8(&buf[o], value, lineno);
            if (!r) {
                LOGVAL(LYE_XML_INVAL, lineno, "character UTF8 character");
                goto error;
            }
            o += r - 1; /* o is ++ in for loop */
            (*len) += i; /* number of read characters */
        } else if (data[*len] < 0x20 || data[*len] == 0x5c) {
            /* control characters must be escaped */
            LOGVAL(LYE_XML_INVAL, lineno, "control character (unescaped)");
            goto error;
        } else {
            /* unescaped character */
            buf[o] = data[*len];
            COUNTLINE(buf[o]);
            (*len)++;
        }
    }

#undef BUFSIZE

    if (o) {
        if (result) {
            size = size + o;
            aux = realloc(result, size + 1);
            result = aux;
        } else {
            size = o;
            result = malloc((size + 1) * sizeof *result);
        }
        memcpy(&result[size - o], buf, o);
    }
    if (result) {
        result[size] = '\0';
    } else {
        size = 0;
        result = strdup("");
    }

    return result;

error:
    free(result);
    return NULL;
}

static unsigned int
lyjson_parse_number(const char *data)
{
    unsigned int len;
    unsigned int i = 0;

    for (len = 0;
         data[len] && data[len] != ',' && data[len] != ']' && data[len] != '}' && !lyjson_isspace(data[len]);
         len++) {

        switch(data[len]) {
        case '0':
            if (!i && data[len + 1] != ';' && !lyjson_isspace(data[len + 1])) {
                /* leading 0 is not allowed */
                LOGVAL(LYE_XML_INVAL, lineno, "JSON number (leading zero)");
                return 0;
            }
            /* no break */
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            i = 1;
            /* no break */
        case 0x2d: /* minus */
            /* ok */
            break;
        default:
            LOGVAL(LYE_XML_INVAL, lineno, "character in JSON Number value");
            return 0;
        }
    }

    return len;
}

static unsigned int
lyjson_parse_boolean(const char *data)
{
    unsigned int len;

    if (!strncmp(data, "false", 5)) {
        len = 5;
    } else if (!strncmp(data, "true", 4)) {
        len = 4;
    }

    if (data[len] && data[len] != ',' && data[len] != ']' && data[len] != '}' && !lyjson_isspace(data[len])) {
        LOGVAL(LYE_XML_INVAL, lineno, "JSON literal value (expected true or false)");
        return 0;
    }

    return len;
}

static unsigned int
json_get_anyxml(struct lyd_node_anyxml *axml, const char *data)
{
    unsigned int len = 0;
    char stop, start;
    int level = 0;

    switch (data[len]) {
    case '"':
        start = 0;
        stop = '"';
        level = 1;
        break;
    case '[':
        start = '[';
        stop = ']';
        break;
    case '{':
        start = '{';
        stop = '}';
        break;
    default:
        /* number or one of literals */
        while (!isspace(data[len])) {
            len++;
        }
        axml->value = NULL; /* TODO ??? */
        return len;
    }

    while (data[len]) {
        if (start && data[len] == start) {
            if (!len || data[len - 1] != '\\') {
                level++;
            }
        } else if (data[len] == stop) {
            if (!len || data[len - 1] != '\\') {
                level--;
            }
        }
        stop = len;
        len++;
        if (!level) {
            /* we are done */
            axml->value = NULL; /* TODO ??? */
            return len;
        }
    }

    return 0;
}

static unsigned int
json_get_value(struct lyd_node_leaf_list *leaf, const char *data, int options, struct unres_data *unres)
{
    struct lyd_node_leaf_list *new, *diter;
    struct lys_type *stype, *type;
    struct ly_ctx *ctx;
    unsigned int len = 0, r;
    int found, resolve;
    char *str;

    assert(leaf && data && unres);
    ctx = leaf->schema->module->ctx;

    if (options & (LYD_OPT_FILTER | LYD_OPT_EDIT)) {
        resolve = 0;
    } else {
        resolve = 1;
    }

    stype = &((struct lys_node_leaf *)leaf->schema)->type;

    if (options & LYD_OPT_FILTER) {
        /* no value in filter (selection) node is accepted in this case */
        if (!strncmp(&data[len], "null", 4)) {
            leaf->value_type = stype->base;
            len +=4;
            goto end;
        }
    }

    if (leaf->schema->nodetype == LYS_LEAFLIST) {
        /* expecting begin-array */
        if (data[len++] != '[') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (expected begin-array)");
            return 0;
        }

repeat:
        len += skip_ws(&data[len]);
    }

    /* will be changed in case of union */
    leaf->value_type = stype->base;

    if (data[len] == '"') {
        /* string representations */
        if (data[len++] != '"') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing quotation-mark at the beginning of string)");
            return 0;
        }
        str = lyjson_parse_text(&data[len], &r);
        if (!str) {
            return 0;
        }
        leaf->value_str = lydict_insert_zc(ctx, str);
        if (data[len + r] != '"') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing quotation-mark at the end of string)");
            return 0;
        }
        len += r + 1;
    } else if (data[len] == '-' || isdigit(data[len])) {
        /* numeric type */
        r = lyjson_parse_number(&data[len]);
        if (!r) {
            return 0;
        }
        leaf->value_str = lydict_insert(ctx, &data[len], r);
        len += r;
    } else if (data[len] == 'f' || data[len] == 't') {
        /* boolean */
        r = lyjson_parse_boolean(&data[len]);
        if (!r) {
            return 0;
        }
        leaf->value_str = lydict_insert(ctx, &data[len], r);
        len += r;
    } else if (!strncmp(&data[len], "[null]", 6)) {
        /* empty */
        leaf->value_str = NULL;
        len += 6;
    } else {
        /* error */
        LOGVAL(LYE_XML_INVAL, lineno, "JSON data (unexpected value)");
        return 0;
    }

    if (stype->base == LY_TYPE_UNION) {
        found = 0;
        type = lyp_get_next_union_type(stype, NULL, &found);
        while (type) {
            leaf->value_type = type->base;

            if (!lyp_parse_value(leaf, type, resolve, unres, UINT_MAX)) {
                break;
            }

            found = 0;
            type = lyp_get_next_union_type(stype, type, &found);
        }

        if (!type) {
            LOGVAL(LYE_INVAL, lineno, (leaf->value_str ? leaf->value_str : ""), leaf->schema->name);
            return 0;
        }
    } else if (lyp_parse_value(leaf, stype, resolve, unres, lineno)) {
        ly_errno = LY_EVALID;
        return 0;
    }

    if (leaf->schema->nodetype == LYS_LEAFLIST) {
        /* repeat until end-array */
        len += skip_ws(&data[len]);
        if (data[len] == ',') {
            /* another instance of the leaf-list */
            new = calloc(1, sizeof(struct lyd_node_leaf_list));
            new->parent = leaf->parent;
            new->prev = (struct lyd_node *)leaf;
            leaf->next = (struct lyd_node *)new;

            /* fix the "last" pointer */
            for (diter = leaf; diter->prev != (struct lyd_node *)leaf; diter = (struct lyd_node_leaf_list *)diter->prev);
            diter->prev = (struct lyd_node *)new;

            new->schema = leaf->schema;

            /* repeat value parsing */
            leaf = new;
            len++;
            goto repeat;
        } else if (data[len] == ']') {
            len++;
            len += skip_ws(&data[len]);
        } else {
            /* something unexpected */
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (expecting value-separator or end-array)");
            return 0;
        }
    }

end:
    len += skip_ws(&data[len]);
    return len;
}

static unsigned int
json_parse_data(struct ly_ctx *ctx, const char *data, struct lyd_node **parent, struct lyd_node *prev,
                int options, struct unres_data *unres)
{
    unsigned int len = 0;
    unsigned int r;
    int flag_object = 0;
    char *name, *prefix = NULL, *str;
    struct lys_module *module = NULL;
    struct lys_node *schema = NULL;
    struct lyd_node *result = NULL, *new, *list, *diter = NULL;

    /* skip leading whitespaces */
    len += skip_ws(&data[len]);

    /* skip top-level { if any */
    if (data[len] == '{') {
        flag_object = 1;
        len++;
        len += skip_ws(&data[len]);
    }

    /* each YANG data node representation starts with string (node identifier) */
    if (data[len] != '"') {
        goto error;
    }
    len++;

    str = lyjson_parse_text(&data[len], &r);
    if (!r) {
        goto error;
    } else if (data[len + r] != '"') {
        LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing quotation-mark at the end of string)");
        goto error;
    }
    if ((name = strchr(str, ':'))) {
        *name = '\0';
        name++;
        prefix = str;
    } else {
        name = str;
    }

    /* TODO - process attributes (@) */

    /* prepare data for parsing node content */
    len += r + 1;
    len += skip_ws(&data[len]);
    if (data[len] != ':') {
        LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing name-separator)");
        goto error;
    }
    len++;
    len += skip_ws(&data[len]);

    /* find schema node */
    if (!(*parent)) {
        /* starting in root */
        /* get the proper schema */
        module = ly_ctx_get_module(ctx, prefix, NULL);
        if (module) {
            /* get the proper schema node */
            LY_TREE_FOR(module->data, schema) {
                if (!strcmp(schema->name, name)) {
                    break;
                }
            }
        }
    } else {
        /* parsing some internal node, we start with parent's schema pointer */
        if (prefix) {
            /* get the proper schema */
            module = ly_ctx_get_module(ctx, prefix, NULL);
            if (!module) {
                LOGVAL(LYE_INELEM, lineno, name);
                free(prefix);
                return 0;
            }
        }
        while ((schema = lys_getnext(schema, (*parent)->schema, module, 0))) {
            if (!strcmp(schema->name, name)) {
                break;
            }
        }
    }
    if (!schema) {
        LOGVAL(LYE_INELEM, lineno, name);
        free(str);
        return 0;
    }
    free(str);

    switch (schema->nodetype) {
    case LYS_CONTAINER:
    case LYS_LIST:
    case LYS_NOTIF:
    case LYS_RPC:
        result = calloc(1, sizeof *result);
        break;
    case LYS_LEAF:
    case LYS_LEAFLIST:
        result = calloc(1, sizeof(struct lyd_node_leaf_list));
        break;
    case LYS_ANYXML:
        result = calloc(1, sizeof(struct lyd_node_anyxml));
        break;
    default:
        LOGINT;
        return 0;
    }
    result->parent = *parent;
    if (*parent && !(*parent)->child) {
        (*parent)->child = result;
    }
    if (prev) {
        result->prev = prev;
        prev->next = result;

        /* fix the "last" pointer */
        for (diter = prev; diter->prev != prev; diter = diter->prev);
        diter->prev = result;
    } else {
        result->prev = result;
    }
    result->schema = schema;

    if (lyv_data_context(result, options, lineno, unres)) {
        goto error;
    }

    /* type specific processing */
    if (schema->nodetype & (LYS_LEAF | LYS_LEAFLIST)) {
        /* type detection and assigning the value */
        r = json_get_value((struct lyd_node_leaf_list *)result, &data[len], options, unres);
        if (!r) {
            goto error;
        }
        len += r;
        len += skip_ws(&data[len]);
    } else if (schema->nodetype == LYS_ANYXML) {
        r = json_get_anyxml((struct lyd_node_anyxml *)result, &data[len]);
        if (!r) {
            goto error;
        }
        len += r;
        len += skip_ws(&data[len]);
    } else if (schema->nodetype == LYS_CONTAINER) {
        if (data[len] != '{') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing begin-object)");
            goto error;
        }
        len++;
        len += skip_ws(&data[len]);

        if (data[len] != '}') {
            /* non-empty container */
            r = json_parse_data(ctx, &data[len], &result, NULL, options, unres);
            if (!r) {
                goto error;
            }
            len += r;
        }

        if (data[len] != '}') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing end-object)");
            goto error;
        }
        len++;
        len += skip_ws(&data[len]);

    } else if (schema->nodetype == LYS_LIST) {
        if (data[len] != '[') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing begin-array)");
            goto error;
        }

        list = result;
        do {
            len++;
            len += skip_ws(&data[len]);

            if (options & LYD_OPT_FILTER) {
                /* filter selection node ? */
                if (data[len] == ']') {
                    break;
                } else if (!strcmp(&data[len], "null")) {
                    len += 4;
                    len += skip_ws(&data[len]);
                    break;
                }
            }

            r = json_parse_data(ctx, &data[len], &list, NULL, options, unres);
            if (!r) {
                goto error;
            }
            len += r;
            len += skip_ws(&data[len]);

            if (data[len] == ',') {
                /* another instance of the list */
                new = calloc(1, sizeof *new);
                new->parent = list->parent;
                new->prev = list;
                list->next = new;

                /* fix the "last" pointer */
                for (diter = list; diter->prev != list; diter = diter->prev);
                diter->prev = new;

                new->schema = list->schema;

                /* various validation checks */
                ly_errno = 0;
                if (lyv_data_content(list, options, lineno, unres)) {
                    if (ly_errno) {
                        goto error;
                    }
                }
                list = new;
            }
        } while (data[len] == ',');
        result = list;

        if (data[len] != ']') {
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing end-array)");
            goto error;
        }
        len++;
        len += skip_ws(&data[len]);
    }

    /* various validation checks */
    ly_errno = 0;
    if (lyv_data_content(result, options, lineno, unres)) {
        if (ly_errno) {
            goto error;
        }
    }

    /* process siblings */
    if (data[len] && data[len] == ',') {
        /* have siblings */
        len++;
        len += skip_ws(&data[len]);

        r = json_parse_data(ctx, &data[len], parent, result, options, unres);
        if (!r) {
            goto error;
        }

        len += r;
    } else {
        len += skip_ws(&data[len]);
    }

    if (flag_object) {
        if (data[len] != '}') {
            /* expecting end-object */
            LOGVAL(LYE_XML_INVAL, lineno, "JSON data (missing end-object)");
            goto error;
        }
        len++;
        len += skip_ws(&data[len]);
    }


    if (!(*parent)) {
        *parent = result;
    }
    return len;

error:
    lyd_free(result);
    return 0;
}

struct lyd_node *
lyd_parse_json(struct ly_ctx *ctx, const char *data, int options)
{
    struct lyd_node *result, *next, *iter;
    struct unres_data *unres = NULL;

    if (!ctx || !data) {
        LOGERR(LY_EINVAL, "%s: Invalid parameter.", __func__);
        return NULL;
    }

    unres = calloc(1, sizeof *unres);

#ifndef NDEBUG
    lineno = 0;
#endif
    ly_errno = 0;
    result = NULL;
    json_parse_data(ctx, data, &result, NULL, options, unres);

    /* check leafrefs and/or instids if any */
    if (result && resolve_unres_data(unres)) {
        /* leafref & instid checking failed */
        LY_TREE_FOR_SAFE(result, next, iter)
        {
            lyd_free(iter);
        }
        result = NULL;
    }

    free(unres->node);
    free(unres->type);
#ifndef NDEBUG
    free(unres->line);
#endif
    free(unres);

    return result;
}