/*

 * JavaScript Object Notation (JSON) parser (RFC7159)

 * Copyright (c) 2017, Qualcomm Atheros, Inc.

 *

 * This software may be distributed under the terms of the BSD license.

 * See README for more details.

 */

#include "includes.h"

#include "common.h"

#include "base64.h"

#include "json.h"

#define JSON_MAX_DEPTH 10

#define JSON_MAX_TOKENS 500

void json_escape_string(char *txt, size_t maxlen, const char *data, size_t len)

{

  char *end = txt + maxlen;

  size_t i;

  for (i = 0; i < len; i++) {

    if (txt + 4 >= end)

      break;

    switch (data[i]) {

    case '\"':

      *txt++ = '\\';

      *txt++ = '\"';

      break;

    case '\\':

      *txt++ = '\\';

      *txt++ = '\\';

      break;

    case '\n':

      *txt++ = '\\';

      *txt++ = 'n';

      break;

    case '\r':

      *txt++ = '\\';

      *txt++ = 'r';

      break;

    case '\t':

      *txt++ = '\\';

      *txt++ = 't';

      break;

    default:

      if (data[i] >= 32 && data[i] <= 126) {

        *txt++ = data[i];

      } else {

        txt += os_snprintf(txt, end - txt, "\\u%04x",

               (unsigned char) data[i]);

      }

      break;

    }

  }

  *txt = '\0';

}

static char * json_parse_string(const char **json_pos, const char *end)

{

  const char *pos = *json_pos;

  char *str, *spos, *s_end;

  size_t max_len, buf_len;

  u8 bin[2];

  pos++; /* skip starting quote */

  max_len = end - pos + 1;

  buf_len = max_len > 10 ? 10 : max_len;

  str = os_malloc(buf_len);

  if (!str)

    return NULL;

  spos = str;

  s_end = str + buf_len;

  for (; pos < end; pos++) {

    if (buf_len < max_len && s_end - spos < 3) {

      char *tmp;

      int idx;

      idx = spos - str;

      buf_len *= 2;

      if (buf_len > max_len)

        buf_len = max_len;

      tmp = os_realloc(str, buf_len);

      if (!tmp)

        goto fail;

      str = tmp;

      spos = str + idx;

      s_end = str + buf_len;

    }

    switch (*pos) {

    case '\"': /* end string */

      *spos = '\0';

      /* caller will move to the next position */

      *json_pos = pos;

      return str;

    case '\\':

      pos++;

      if (pos >= end) {

        wpa_printf(MSG_DEBUG,

             "JSON: Truncated \\ escape");

        goto fail;

      }

      switch (*pos) {

      case '"':

      case '\\':

      case '/':

        *spos++ = *pos;

        break;

      case 'n':

        *spos++ = '\n';

        break;

      case 'r':

        *spos++ = '\r';

        break;

      case 't':

        *spos++ = '\t';

        break;

      case 'u':

        if (end - pos < 5 ||

            hexstr2bin(pos + 1, bin, 2) < 0 ||

            bin[1] == 0x00) {

          wpa_printf(MSG_DEBUG,

               "JSON: Invalid \\u escape");

          goto fail;

        }

        if (bin[0] == 0x00) {

          *spos++ = bin[1];

        } else {

          *spos++ = bin[0];

          *spos++ = bin[1];

        }

        pos += 4;

        break;

      default:

        wpa_printf(MSG_DEBUG,

             "JSON: Unknown escape '%c'", *pos);

        goto fail;

      }

      break;

    default:

      *spos++ = *pos;

      break;

    }

  }

fail:

  os_free(str);

  return NULL;

}

static int json_parse_number(const char **json_pos, const char *end,

           int *ret_val)

{

  const char *pos = *json_pos;

  size_t len;

  char *str;

  for (; pos < end; pos++) {

    if (*pos != '-' && (*pos < '0' || *pos > '9')) {

      pos--;

      break;

    }

  }

  if (pos == end)

    pos--;

  if (pos < *json_pos)

    return -1;

  len = pos - *json_pos + 1;

  str = os_malloc(len + 1);

  if (!str)

    return -1;

  os_memcpy(str, *json_pos, len);

  str[len] = '\0';

  *ret_val = atoi(str);

  os_free(str);

  *json_pos = pos;

  return 0;

}

static int json_check_tree_state(struct json_token *token)

{

  if (!token)

    return 0;

  if (json_check_tree_state(token->child) < 0 ||

      json_check_tree_state(token->sibling) < 0)

    return -1;

  if (token->state != JSON_COMPLETED) {

    wpa_printf(MSG_DEBUG,

         "JSON: Unexpected token state %d (name=%s type=%d)",

         token->state, token->name ? token->name : "N/A",

         token->type);

    return -1;

  }

  return 0;

}

static struct json_token * json_alloc_token(unsigned int *tokens)

{

  (*tokens)++;

  if (*tokens > JSON_MAX_TOKENS) {

    wpa_printf(MSG_DEBUG, "JSON: Maximum token limit exceeded");

    return NULL;

  }

  return os_zalloc(sizeof(struct json_token));

}

struct json_token * json_parse(const char *data, size_t data_len)

{

  struct json_token *root = NULL, *curr_token = NULL, *token = NULL;

  const char *pos, *end;

  char *str;

  int num;

  unsigned int depth = 0;

  unsigned int tokens = 0;

  pos = data;

  end = data + data_len;

  for (; pos < end; pos++) {

    switch (*pos) {

    case '[': /* start array */

    case '{': /* start object */

      if (!curr_token) {

        token = json_alloc_token(&tokens);

        if (!token)

          goto fail;

        if (!root)

          root = token;

      } else if (curr_token->state == JSON_WAITING_VALUE) {

        token = curr_token;

      } else if (curr_token->parent &&

           curr_token->parent->type == JSON_ARRAY &&

           curr_token->parent->state == JSON_STARTED &&

           curr_token->state == JSON_EMPTY) {

        token = curr_token;

      } else {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid state for start array/object");

        goto fail;

      }

      depth++;

      if (depth > JSON_MAX_DEPTH) {

        wpa_printf(MSG_DEBUG,

             "JSON: Max depth exceeded");

        goto fail;

      }

      token->type = *pos == '[' ? JSON_ARRAY : JSON_OBJECT;

      token->state = JSON_STARTED;

      token->child = json_alloc_token(&tokens);

      if (!token->child)

        goto fail;

      curr_token = token->child;

      curr_token->parent = token;

      curr_token->state = JSON_EMPTY;

      break;

    case ']': /* end array */

    case '}': /* end object */

      if (!curr_token || !curr_token->parent ||

          curr_token->parent->state != JSON_STARTED ||

          depth == 0) {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid state for end array/object");

        goto fail;

      }

      depth--;

      curr_token = curr_token->parent;

      if ((*pos == ']' &&

           curr_token->type != JSON_ARRAY) ||

          (*pos == '}' &&

           curr_token->type != JSON_OBJECT)) {

        wpa_printf(MSG_DEBUG,

             "JSON: Array/Object mismatch");

        goto fail;

      }

      if (curr_token->child->state == JSON_EMPTY &&

          !curr_token->child->child &&

          !curr_token->child->sibling) {

        /* Remove pending child token since the

         * array/object was empty. */

        json_free(curr_token->child);

        curr_token->child = NULL;

      }

      curr_token->state = JSON_COMPLETED;

      break;

    case '\"': /* string */

      str = json_parse_string(&pos, end);

      if (!str)

        goto fail;

      if (!curr_token) {

        token = json_alloc_token(&tokens);

        if (!token) {

          os_free(str);

          goto fail;

        }

        token->type = JSON_STRING;

        token->string = str;

        token->state = JSON_COMPLETED;

      } else if (curr_token->parent &&

           curr_token->parent->type == JSON_ARRAY &&

           curr_token->parent->state == JSON_STARTED &&

           curr_token->state == JSON_EMPTY) {

        curr_token->string = str;

        curr_token->state = JSON_COMPLETED;

        curr_token->type = JSON_STRING;

        wpa_printf(MSG_MSGDUMP,

             "JSON: String value: '%s'",

             curr_token->string);

      } else if (curr_token->state == JSON_EMPTY) {

        curr_token->type = JSON_VALUE;

        curr_token->name = str;

        curr_token->state = JSON_STARTED;

      } else if (curr_token->state == JSON_WAITING_VALUE) {

        curr_token->string = str;

        curr_token->state = JSON_COMPLETED;

        curr_token->type = JSON_STRING;

        wpa_printf(MSG_MSGDUMP,

             "JSON: String value: '%s' = '%s'",

             curr_token->name,

             curr_token->string);

      } else {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid state for a string");

        os_free(str);

        goto fail;

      }

      break;

    case ' ':

    case '\t':

    case '\r':

    case '\n':

      /* ignore whitespace */

      break;

    case ':': /* name/value separator */

      if (!curr_token || curr_token->state != JSON_STARTED)

        goto fail;

      curr_token->state = JSON_WAITING_VALUE;

      break;

    case ',': /* member separator */

      if (!curr_token)

        goto fail;

      curr_token->sibling = json_alloc_token(&tokens);

      if (!curr_token->sibling)

        goto fail;

      curr_token->sibling->parent = curr_token->parent;

      curr_token = curr_token->sibling;

      curr_token->state = JSON_EMPTY;

      break;

    case 't': /* true */

    case 'f': /* false */

    case 'n': /* null */

      if (!((end - pos >= 4 &&

             os_strncmp(pos, "true", 4) == 0) ||

            (end - pos >= 5 &&

             os_strncmp(pos, "false", 5) == 0) ||

            (end - pos >= 4 &&

             os_strncmp(pos, "null", 4) == 0))) {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid literal name");

        goto fail;

      }

      if (!curr_token) {

        token = json_alloc_token(&tokens);

        if (!token)

          goto fail;

        curr_token = token;

      } else if (curr_token->state == JSON_WAITING_VALUE) {

        wpa_printf(MSG_MSGDUMP,

             "JSON: Literal name: '%s' = %c",

             curr_token->name, *pos);

      } else if (curr_token->parent &&

           curr_token->parent->type == JSON_ARRAY &&

           curr_token->parent->state == JSON_STARTED &&

           curr_token->state == JSON_EMPTY) {

        wpa_printf(MSG_MSGDUMP,

             "JSON: Literal name: %c", *pos);

      } else {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid state for a literal name");

        goto fail;

      }

      switch (*pos) {

      case 't':

        curr_token->type = JSON_BOOLEAN;

        curr_token->number = 1;

        pos += 3;

        break;

      case 'f':

        curr_token->type = JSON_BOOLEAN;

        curr_token->number = 0;

        pos += 4;

        break;

      case 'n':

        curr_token->type = JSON_NULL;

        pos += 3;

        break;

      }

      curr_token->state = JSON_COMPLETED;

      break;

    case '-':

    case '0':

    case '1':

    case '2':

    case '3':

    case '4':

    case '5':

    case '6':

    case '7':

    case '8':

    case '9':

      /* number */

      if (json_parse_number(&pos, end, &num) < 0)

        goto fail;

      if (!curr_token) {

        token = json_alloc_token(&tokens);

        if (!token)

          goto fail;

        token->type = JSON_NUMBER;

        token->number = num;

        token->state = JSON_COMPLETED;

      } else if (curr_token->state == JSON_WAITING_VALUE) {

        curr_token->number = num;

        curr_token->state = JSON_COMPLETED;

        curr_token->type = JSON_NUMBER;

        wpa_printf(MSG_MSGDUMP,

             "JSON: Number value: '%s' = '%d'",

             curr_token->name,

             curr_token->number);

      } else if (curr_token->parent &&

           curr_token->parent->type == JSON_ARRAY &&

           curr_token->parent->state == JSON_STARTED &&

           curr_token->state == JSON_EMPTY) {

        curr_token->number = num;

        curr_token->state = JSON_COMPLETED;

        curr_token->type = JSON_NUMBER;

        wpa_printf(MSG_MSGDUMP,

             "JSON: Number value: %d",

             curr_token->number);

      } else {

        wpa_printf(MSG_DEBUG,

             "JSON: Invalid state for a number");

        goto fail;

      }

      break;

    default:

      wpa_printf(MSG_DEBUG,

           "JSON: Unexpected JSON character: %c", *pos);

      goto fail;

    }

    if (!root)

      root = token;

    if (!curr_token)

      curr_token = token;

  }

  if (json_check_tree_state(root) < 0) {

    wpa_printf(MSG_DEBUG, "JSON: Incomplete token in the tree");

    goto fail;

  }

  return root;

fail:

  wpa_printf(MSG_DEBUG, "JSON: Parsing failed");

  json_free(root);

  return NULL;

}

void json_free(struct json_token *json)

{

  if (!json)

    return;

  json_free(json->child);

  json_free(json->sibling);

  os_free(json->name);

  os_free(json->string);

  os_free(json);

}

struct json_token * json_get_member(struct json_token *json, const char *name)

{

  struct json_token *token, *ret = NULL;

  if (!json || json->type != JSON_OBJECT)

    return NULL;

  /* Return last matching entry */

  for (token = json->child; token; token = token->sibling) {

    if (token->name && os_strcmp(token->name, name) == 0)

      ret = token;

  }

  return ret;

}

struct wpabuf * json_get_member_base64url(struct json_token *json,

            const char *name)

{

  struct json_token *token;

  unsigned char *buf;

  size_t buflen;

  struct wpabuf *ret;

  token = json_get_member(json, name);

  if (!token || token->type != JSON_STRING)

    return NULL;

  buf = base64_url_decode(token->string, os_strlen(token->string),

        &buflen);

  if (!buf)

    return NULL;

  ret = wpabuf_alloc_ext_data(buf, buflen);

  if (!ret)

    os_free(buf);

  return ret;

}

struct wpabuf * json_get_member_base64(struct json_token *json,

               const char *name)

{

  struct json_token *token;

  unsigned char *buf;

  size_t buflen;

  struct wpabuf *ret;

  token = json_get_member(json, name);

  if (!token || token->type != JSON_STRING)

    return NULL;

  buf = base64_decode(token->string, os_strlen(token->string), &buflen);

  if (!buf)

    return NULL;

  ret = wpabuf_alloc_ext_data(buf, buflen);

  if (!ret)

    os_free(buf);

  return ret;

}

static const char * json_type_str(enum json_type type)

{

  switch (type) {

  case JSON_VALUE:

    return "VALUE";

  case JSON_OBJECT:

    return "OBJECT";

  case JSON_ARRAY:

    return "ARRAY";

  case JSON_STRING:

    return "STRING";

  case JSON_NUMBER:

    return "NUMBER";

  case JSON_BOOLEAN:

    return "BOOLEAN";

  case JSON_NULL:

    return "NULL";

  }

  return "??";

}

static void json_print_token(struct json_token *token, int depth,

           char *buf, size_t buflen)

{

  size_t len;

  int ret;

  if (!token)

    return;

  len = os_strlen(buf);

  ret = os_snprintf(buf + len, buflen - len, "[%d:%s:%s]",

        depth, json_type_str(token->type),

        token->name ? token->name : "");

  if (os_snprintf_error(buflen - len, ret)) {

    buf[len] = '\0';

    return;

  }

  json_print_token(token->child, depth + 1, buf, buflen);

  json_print_token(token->sibling, depth, buf, buflen);

}

void json_print_tree(struct json_token *root, char *buf, size_t buflen)

{

  buf[0] = '\0';

  json_print_token(root, 1, buf, buflen);

}

void json_add_int(struct wpabuf *json, const char *name, int val)

{

  wpabuf_printf(json, "\"%s\":%d", name, val);

}

void json_add_string(struct wpabuf *json, const char *name, const char *val)

{

  wpabuf_printf(json, "\"%s\":\"%s\"", name, val);

}

int json_add_string_escape(struct wpabuf *json, const char *name,

         const void *val, size_t len)

{

  char *tmp;

  size_t tmp_len = 6 * len + 1;

  tmp = os_malloc(tmp_len);

  if (!tmp)

    return -1;

  json_escape_string(tmp, tmp_len, val, len);

  json_add_string(json, name, tmp);

  bin_clear_free(tmp, tmp_len);

  return 0;

}

int json_add_base64url(struct wpabuf *json, const char *name, const void *val,

           size_t len)

{

  char *b64;

  b64 = base64_url_encode(val, len, NULL);

  if (!b64)

    return -1;

  json_add_string(json, name, b64);

  os_free(b64);

  return 0;

}

int json_add_base64(struct wpabuf *json, const char *name, const void *val,

        size_t len)

{

  char *b64;

  b64 = base64_encode_no_lf(val, len, NULL);

  if (!b64)

    return -1;

  json_add_string(json, name, b64);

  os_free(b64);

  return 0;

}

void json_start_object(struct wpabuf *json, const char *name)

{

  if (name)

    wpabuf_printf(json, "\"%s\":", name);

  wpabuf_put_u8(json, '{');

}

void json_end_object(struct wpabuf *json)

{

  wpabuf_put_u8(json, '}');

}

void json_start_array(struct wpabuf *json, const char *name)

{

  if (name)

    wpabuf_printf(json, "\"%s\":", name);

  wpabuf_put_u8(json, '[');

}

void json_end_array(struct wpabuf *json)

{

  wpabuf_put_u8(json, ']');

}

void json_value_sep(struct wpabuf *json)

{

  wpabuf_put_u8(json, ',');

}