--- /dev/null
+
+/*
+ * Copyright (C) Maxim Dounin
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+/*
+ * JSON parser. RFC 8259 for the JSON grammar.
+
+ * Site http://json.org/ may be useful too.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_json_parse.h>
+
+
+#define NGX_JSON_NOT_SKIPPING (ngx_uint_t) -1
+#define ngx_json_skipping(d) ((d) != NGX_JSON_NOT_SKIPPING)
+#define ngx_json_ws(c) ((c) == ' ' || (c) == '\t' || (c) == CR || (c) == LF)
+
+
+static ngx_inline ngx_int_t ngx_json_end_number(ngx_json_ctx_t *ctx,
+ u_char *start, u_char *end, ngx_json_state_e *state);
+static ngx_inline ngx_int_t ngx_json_emit(ngx_json_ctx_t *ctx,
+ ngx_json_event_e event, u_char *data, size_t len);
+static ngx_inline ngx_json_state_e ngx_json_after_value(ngx_json_ctx_t *ctx);
+static ngx_inline ngx_int_t ngx_json_close(ngx_json_ctx_t *ctx,
+ ngx_json_event_e event, ngx_json_state_e *state, u_char *p);
+static ngx_int_t ngx_json_push_state(ngx_json_ctx_t *ctx,
+ ngx_json_container_e container);
+
+
+void
+ngx_json_ctx_init(ngx_json_ctx_t *ctx, ngx_pool_t *pool)
+{
+ ctx->state = ngx_json_start;
+ ctx->pool = pool;
+ ctx->handler = NULL;
+ ctx->data = NULL;
+ ctx->codepoint = 0;
+ ctx->hex_left = 0;
+
+ ctx->depth = 0;
+ ctx->skip_until_depth = NGX_JSON_NOT_SKIPPING;
+ ctx->max_depth = NGX_JSON_DEFAULT_MAX_DEPTH;
+
+ /* stack is allocated lazily on first push, sized to max_depth */
+
+ ctx->stack = NULL;
+
+ ctx->in_key = 0;
+}
+
+
+ngx_int_t
+ngx_json_parse_ctx(ngx_json_ctx_t *ctx, u_char *data, size_t len)
+{
+ u_char *p, *last, *start;
+ ngx_int_t rc, hd;
+ ngx_uint_t skip_depth;
+ ngx_json_state_e state;
+
+ if (len == 0) {
+ return NGX_DECLINED;
+ }
+
+ if (data == NULL) {
+ return NGX_ERROR;
+ }
+
+ if (ctx->state == ngx_json_done) {
+ return NGX_DECLINED;
+ }
+
+ last = data + len;
+ state = ctx->state;
+ skip_depth = ctx->skip_until_depth;
+ start = NULL;
+
+ for (p = data; p < last; p++) {
+
+ /* skipping suppresses emission only; the machine still validates */
+
+ if (ngx_json_skipping(skip_depth) && ctx->depth <= skip_depth
+ && (state == ngx_json_object_value_separator
+ || state == ngx_json_array_value_separator
+ || state == ngx_json_done))
+ {
+ skip_depth = NGX_JSON_NOT_SKIPPING;
+ ctx->skip_until_depth = NGX_JSON_NOT_SKIPPING;
+ p--;
+
+ continue;
+ }
+
+ switch (state) {
+
+ case ngx_json_start:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == '{') {
+ rc = ngx_json_push_state(ctx, ngx_json_ctx_object);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ if (ngx_json_emit(ctx, NGX_JSON_OBJECT_OPEN, p, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ state = ngx_json_object;
+ break;
+ }
+
+ if (*p == '[') {
+ rc = ngx_json_push_state(ctx, ngx_json_ctx_array);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ if (ngx_json_emit(ctx, NGX_JSON_ARRAY_OPEN, p, 1) != NGX_OK) {
+ return NGX_ERROR;
+ }
+
+ state = ngx_json_array;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_object:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == '}') {
+ rc = ngx_json_close(ctx, NGX_JSON_OBJECT_CLOSE, &state, p);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+ }
+
+ /* fall through */
+
+ case ngx_json_object_next:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == '"') {
+ ctx->in_key = 1;
+ start = p + 1;
+ state = ngx_json_string;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_object_name_separator:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == ':') {
+ state = ngx_json_value;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_object_value_separator:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == ',') {
+ state = ngx_json_object_next;
+ break;
+ }
+
+ if (*p == '}') {
+ rc = ngx_json_close(ctx, NGX_JSON_OBJECT_CLOSE, &state, p);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_array_value_separator:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == ',') {
+ state = ngx_json_value;
+ break;
+ }
+
+ if (*p == ']') {
+ rc = ngx_json_close(ctx, NGX_JSON_ARRAY_CLOSE, &state, p);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_array:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ if (*p == ']') {
+ rc = ngx_json_close(ctx, NGX_JSON_ARRAY_CLOSE, &state, p);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+ }
+
+ /* fall through */
+
+ case ngx_json_value:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ start = p;
+
+ if (*p == '"') {
+ ctx->in_key = 0;
+ start = p + 1;
+ state = ngx_json_string;
+ break;
+ }
+
+ if (*p == '{') {
+ rc = ngx_json_emit(ctx, NGX_JSON_OBJECT_OPEN, p, 1);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ rc = ngx_json_push_state(ctx, ngx_json_ctx_object);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_object;
+ break;
+ }
+
+ if (*p == '[') {
+ rc = ngx_json_emit(ctx, NGX_JSON_ARRAY_OPEN, p, 1);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ rc = ngx_json_push_state(ctx, ngx_json_ctx_array);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_array;
+ break;
+ }
+
+ if (*p == '-') {
+ state = ngx_json_number_minus;
+ break;
+ }
+
+ if (*p == '0') {
+ state = ngx_json_number_int_zero;
+ break;
+ }
+
+ if (*p >= '1' && *p <= '9') {
+ state = ngx_json_number_int;
+ break;
+ }
+
+ if (*p == 't') {
+ state = ngx_json_true_t;
+ break;
+ }
+
+ if (*p == 'f') {
+ state = ngx_json_false_f;
+ break;
+ }
+
+ if (*p == 'n') {
+ state = ngx_json_null_n;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_string:
+ if (*p == '"') {
+
+ if (ctx->in_key) {
+ rc = ngx_json_emit(ctx, NGX_JSON_KEY, start, p - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ ctx->in_key = 0;
+ state = ngx_json_object_name_separator;
+
+ } else {
+ rc = ngx_json_emit(ctx, NGX_JSON_VALUE_STRING, start,
+ p - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_after_value(ctx);
+ }
+
+ break;
+ }
+
+ if (*p == '\\') {
+ state = ngx_json_escaped;
+ break;
+ }
+
+ if (*p < ' ') {
+ return NGX_DECLINED;
+ }
+
+ break;
+
+ case ngx_json_escaped:
+ if (*p == '"' || *p == '\\' || *p == '/' || *p == 'b'
+ || *p == 'f' || *p == 'n' || *p == 'r' || *p == 't')
+ {
+ state = ngx_json_string;
+ break;
+ }
+
+ if (*p == 'u') {
+ ctx->codepoint = 0;
+ ctx->hex_left = 4;
+ state = ngx_json_escaped_hex;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_escaped_hex:
+
+ /* accumulate the four hex digits of the first \uXXXX escape */
+
+ hd = ngx_json_hex_digit(*p);
+ if (hd == NGX_ERROR) {
+ return NGX_DECLINED;
+ }
+
+ ctx->codepoint = (ctx->codepoint << 4) | (uint32_t) hd;
+
+ if (--ctx->hex_left > 0) {
+ break;
+ }
+
+ if (ctx->codepoint >= 0xD800 && ctx->codepoint <= 0xDBFF) {
+ /* high surrogate - must be followed by \uDC00..\uDFFF */
+ state = ngx_json_surrogate_start;
+ break;
+ }
+
+ if (ctx->codepoint >= 0xDC00 && ctx->codepoint <= 0xDFFF) {
+ /* lone low surrogate */
+ return NGX_DECLINED;
+ }
+
+ state = ngx_json_string;
+ break;
+
+ case ngx_json_surrogate_start:
+ if (*p == '\\') {
+ state = ngx_json_surrogate_u;
+ break;
+ }
+
+ /* high surrogate not followed by \uXXXX */
+ return NGX_DECLINED;
+
+ case ngx_json_surrogate_u:
+ if (*p == 'u') {
+ ctx->codepoint = 0;
+ ctx->hex_left = 4;
+ state = ngx_json_surrogate_hex;
+ break;
+ }
+
+ /* high surrogate followed by non-\u escape */
+ return NGX_DECLINED;
+
+ case ngx_json_surrogate_hex:
+
+ /* accumulate the four hex digits of the low \uXXXX escape */
+
+ hd = ngx_json_hex_digit(*p);
+ if (hd == NGX_ERROR) {
+ return NGX_DECLINED;
+ }
+
+ ctx->codepoint = (ctx->codepoint << 4) | (uint32_t) hd;
+
+ if (--ctx->hex_left > 0) {
+ break;
+ }
+
+ if (ctx->codepoint >= 0xDC00 && ctx->codepoint <= 0xDFFF) {
+ /* valid surrogate pair */
+ state = ngx_json_string;
+ break;
+ }
+
+ /* high surrogate not followed by low surrogate */
+ return NGX_DECLINED;
+
+ case ngx_json_number_minus:
+ if (*p >= '1' && *p <= '9') {
+ state = ngx_json_number_int;
+ break;
+ }
+
+ if (*p == '0') {
+ state = ngx_json_number_int_zero;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_number_int_zero:
+ if (*p == '.') {
+ state = ngx_json_number_frac;
+ break;
+ }
+
+ if (*p == 'e' || *p == 'E') {
+ /* No sense, but permitted by RFC */
+ state = ngx_json_number_exp;
+ break;
+ }
+
+ p--;
+
+ rc = ngx_json_end_number(ctx, start, p + 1, &state);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+
+ case ngx_json_number_int:
+ if (*p >= '0' && *p <= '9') {
+ break;
+ }
+
+ if (*p == '.') {
+ state = ngx_json_number_frac;
+ break;
+ }
+
+ if (*p == 'e' || *p == 'E') {
+ /* No sense, but permitted by RFC */
+ state = ngx_json_number_exp;
+ break;
+ }
+
+ p--;
+
+ rc = ngx_json_end_number(ctx, start, p + 1, &state);
+ if (rc!= NGX_OK) {
+ return rc;
+ }
+
+ break;
+
+ case ngx_json_number_frac:
+ if (*p >= '0' && *p <= '9') {
+ state = ngx_json_number_frac_digit;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_number_frac_digit:
+ if (*p >= '0' && *p <= '9') {
+ break;
+ }
+
+ if (*p == 'e' || *p == 'E') {
+ state = ngx_json_number_exp;
+ break;
+ }
+
+ p--;
+
+ rc = ngx_json_end_number(ctx, start, p + 1, &state);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+
+ case ngx_json_number_exp:
+ if (*p == '-' || *p == '+') {
+ state = ngx_json_number_exp_plusminus;
+ break;
+ }
+
+ if (*p >= '0' && *p <= '9') {
+ state = ngx_json_number_exp_digit;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_number_exp_plusminus:
+ if (*p >= '0' && *p <= '9') {
+ state = ngx_json_number_exp_digit;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_number_exp_digit:
+ if (*p >= '0' && *p <= '9') {
+ break;
+ }
+
+ p--;
+
+ rc = ngx_json_end_number(ctx, start, p + 1, &state);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ break;
+
+ case ngx_json_true_t:
+ if (*p == 'r') {
+ state = ngx_json_true_tr;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_true_tr:
+ if (*p == 'u') {
+ state = ngx_json_true_tru;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_true_tru:
+ if (*p == 'e') {
+ rc = ngx_json_emit(ctx, NGX_JSON_VALUE_BOOL, start,
+ p + 1 - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_after_value(ctx);
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_false_f:
+ if (*p == 'a') {
+ state = ngx_json_false_fa;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_false_fa:
+ if (*p == 'l') {
+ state = ngx_json_false_fal;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_false_fal:
+ if (*p == 's') {
+ state = ngx_json_false_fals;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_false_fals:
+ if (*p == 'e') {
+ rc = ngx_json_emit(ctx, NGX_JSON_VALUE_BOOL, start,
+ p + 1 - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_after_value(ctx);
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_null_n:
+ if (*p == 'u') {
+ state = ngx_json_null_nu;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_null_nu:
+ if (*p == 'l') {
+ state = ngx_json_null_nul;
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_null_nul:
+ if (*p == 'l') {
+ rc = ngx_json_emit(ctx, NGX_JSON_VALUE_NULL, start,
+ p + 1 - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ state = ngx_json_after_value(ctx);
+ break;
+ }
+
+ return NGX_DECLINED;
+
+ case ngx_json_done:
+ if (ngx_json_ws(*p)) {
+ break;
+ }
+
+ return NGX_DECLINED;
+ }
+
+ skip_depth = ctx->skip_until_depth;
+ }
+
+ ctx->state = state;
+
+ if (state == ngx_json_done) {
+ return NGX_OK;
+ }
+
+ return NGX_DECLINED;
+}
+
+
+ngx_int_t
+ngx_json_parse(ngx_pool_t *pool, ngx_str_t *json, ngx_json_handler_pt handler,
+ void *data)
+{
+ ngx_json_ctx_t jctx;
+
+ ngx_json_ctx_init(&jctx, pool);
+
+ jctx.data = data;
+ jctx.handler = handler;
+
+ return ngx_json_parse_ctx(&jctx, json->data, json->len);
+}
+
+
+static ngx_inline ngx_int_t
+ngx_json_end_number(ngx_json_ctx_t *ctx, u_char *start, u_char *end,
+ ngx_json_state_e *state)
+{
+ ngx_int_t rc;
+
+ rc = ngx_json_emit(ctx, NGX_JSON_VALUE_NUMBER, start, end - start);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ *state = ngx_json_after_value(ctx);
+
+ return NGX_OK;
+}
+
+
+static ngx_inline ngx_int_t
+ngx_json_emit(ngx_json_ctx_t *ctx, ngx_json_event_e event, u_char *data,
+ size_t len)
+{
+ ngx_int_t rc;
+ ngx_str_t token;
+
+ if (ngx_json_skipping(ctx->skip_until_depth)) {
+ return NGX_OK;
+ }
+
+ if (ctx->handler == NULL) {
+ return NGX_OK;
+ }
+
+ token.data = data;
+ token.len = len;
+ rc = ctx->handler(ctx, event, &token);
+
+ if (rc == NGX_JSON_SKIP) {
+
+ /*
+ * NGX_JSON_SKIP prunes the rest of the current container. It is
+ * honoured only where it is meaningful:
+ *
+ * - OBJECT_OPEN / ARRAY_OPEN: skip the whole container;
+ * - a scalar VALUE_* that is an array element: skip the rest of
+ * that array.
+ *
+ * A skip requested on a CLOSE, or on an object member value, is
+ * ignored: object members are navigated by KEY (use a KEY skip),
+ * and a CLOSE fires after the container is already complete.
+ */
+
+ switch (event) {
+
+ case NGX_JSON_KEY:
+ case NGX_JSON_OBJECT_OPEN:
+ case NGX_JSON_ARRAY_OPEN:
+ ctx->skip_until_depth = ctx->depth;
+ break;
+
+ case NGX_JSON_VALUE_STRING:
+ case NGX_JSON_VALUE_NUMBER:
+ case NGX_JSON_VALUE_BOOL:
+ case NGX_JSON_VALUE_NULL:
+ if (ctx->depth > 0
+ && ctx->stack[ctx->depth - 1] == ngx_json_ctx_array
+ ) {
+ ctx->skip_until_depth = ctx->depth - 1;
+ }
+ break;
+
+ default:
+ break;
+ }
+
+ return NGX_OK;
+ }
+
+ return rc;
+}
+
+
+static ngx_inline ngx_json_state_e
+ngx_json_after_value(ngx_json_ctx_t *ctx)
+{
+ if (ctx->depth == 0) {
+ return ngx_json_done;
+ }
+
+ if (ctx->stack[ctx->depth - 1] == ngx_json_ctx_object) {
+ return ngx_json_object_value_separator;
+ }
+
+ return ngx_json_array_value_separator;
+}
+
+
+static ngx_inline ngx_int_t
+ngx_json_close(ngx_json_ctx_t *ctx, ngx_json_event_e event,
+ ngx_json_state_e *state, u_char *p)
+{
+ ngx_int_t rc;
+
+ ctx->depth--;
+
+ rc = ngx_json_emit(ctx, event, p, 1);
+ if (rc != NGX_OK) {
+ return rc;
+ }
+
+ *state = ngx_json_after_value(ctx);
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_json_push_state(ngx_json_ctx_t *ctx, ngx_json_container_e container)
+{
+ ngx_json_container_e *stack;
+
+ if (ctx->depth >= ctx->max_depth) {
+ return NGX_DECLINED;
+ }
+
+ if (ctx->stack == NULL) {
+ stack = ngx_palloc(ctx->pool,
+ ctx->max_depth * sizeof(ngx_json_container_e));
+ if (stack == NULL) {
+ return NGX_ERROR;
+ }
+
+ ctx->stack = stack;
+ }
+
+ ctx->stack[ctx->depth] = container;
+ ctx->depth++;
+
+ return NGX_OK;
+}
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