/*

 * Copyright 2023-2025 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include "internal/json_enc.h"

#include "internal/nelem.h"

#include "internal/numbers.h"

#include <string.h>

#include <stdbool.h>

/*

 * wbuf

 * ====

 */

static int wbuf_flush(struct json_write_buf *wbuf, int full);

static int wbuf_init(struct json_write_buf *wbuf, BIO *bio, size_t alloc)

{

    wbuf->buf = OPENSSL_malloc(alloc);

    if (wbuf->buf == NULL)

        return 0;

    wbuf->cur   = 0;

    wbuf->alloc = alloc;

    wbuf->bio   = bio;

    return 1;

}

static void wbuf_cleanup(struct json_write_buf *wbuf)

{

    OPENSSL_free(wbuf->buf);

    wbuf->buf   = NULL;

    wbuf->alloc = 0;

}

static void wbuf_set0_bio(struct json_write_buf *wbuf, BIO *bio)

{

    wbuf->bio = bio;

}

/* Empty write buffer. */

static ossl_inline void wbuf_clean(struct json_write_buf *wbuf)

{

    wbuf->cur = 0;

}

/* Available data remaining in buffer. */

static ossl_inline size_t wbuf_avail(struct json_write_buf *wbuf)

{

    return wbuf->alloc - wbuf->cur;

}

/* Add character to write buffer, returning 0 on flush failure. */

static ossl_inline int wbuf_write_char(struct json_write_buf *wbuf, char c)

{

    if (wbuf_avail(wbuf) == 0) {

        if (!wbuf_flush(wbuf, /*full=*/0))

            return 0;

    }

    wbuf->buf[wbuf->cur++] = c;

    return 1;

}

/*

 * Write zero-terminated string to write buffer, returning 0 on flush failure.

 */

static int wbuf_write_str(struct json_write_buf *wbuf, const char *s)

{

    char c;

    while ((c = *s++) != 0)

        if (!wbuf_write_char(wbuf, c))

            return 0;

    return 1;

}

/* Flush write buffer, returning 0 on I/O failure. */

static int wbuf_flush(struct json_write_buf *wbuf, int full)

{

    size_t written = 0, total_written = 0;

    while (total_written < wbuf->cur) {

        if (!BIO_write_ex(wbuf->bio,

                          wbuf->buf + total_written,

                          wbuf->cur - total_written,

                          &written)) {

            memmove(wbuf->buf,

                    wbuf->buf + total_written,

                    wbuf->cur - total_written);

            wbuf->cur = 0;

            return 0;

        }

        total_written += written;

    }

    wbuf->cur = 0;

    if (full)

        (void)BIO_flush(wbuf->bio); /* best effort */

    return 1;

}

/*

 * OSSL_JSON_ENC: Stack Management

 * ===============================

 */

static int json_ensure_stack_size(OSSL_JSON_ENC *json, size_t num_bytes)

{

    unsigned char *stack;

    if (json->stack_bytes >= num_bytes)

        return 1;

    if (num_bytes <= OSSL_NELEM(json->stack_small)) {

        stack = json->stack_small;

    } else {

        if (json->stack == json->stack_small)

            json->stack = NULL;

        stack = OPENSSL_realloc(json->stack, num_bytes);

        if (stack == NULL)

            return 0;

    }

    json->stack         = stack;

    json->stack_bytes   = num_bytes;

    return 1;

}

/* Push one bit onto the stack. Returns 0 on allocation failure. */

static int json_push(OSSL_JSON_ENC *json, unsigned int v)

{

    if (v > 1)

        return 0;

    if (json->stack_end_byte >= json->stack_bytes) {

        size_t new_size

            = (json->stack_bytes == 0)

            ? OSSL_NELEM(json->stack_small)

            : (json->stack_bytes * 2);

        if (!json_ensure_stack_size(json, new_size))

            return 0;

        json->stack_bytes = new_size;

    }

    if (v > 0)

        json->stack[json->stack_end_byte] |= (v << json->stack_end_bit);

    else

        json->stack[json->stack_end_byte] &= ~(1U << json->stack_end_bit);

    json->stack_end_bit = (json->stack_end_bit + 1) % CHAR_BIT;

    if (json->stack_end_bit == 0)

        ++json->stack_end_byte;

    return 1;

}

/*

 * Pop a bit from the stack. Returns 0 if stack is empty. Use json_peek() to get

 * the value before calling this.

 */

static int json_pop(OSSL_JSON_ENC *json)

{

    if (json->stack_end_byte == 0 && json->stack_end_bit == 0)

        return 0;

    if (json->stack_end_bit == 0) {

        --json->stack_end_byte;

        json->stack_end_bit = CHAR_BIT - 1;

    } else {

        --json->stack_end_bit;

    }

    return 1;

}

/*

 * Returns the bit on the top of the stack, or -1 if the stack is empty.

 */

static int json_peek(OSSL_JSON_ENC *json)

{

    size_t obyte, obit;

    obyte = json->stack_end_byte;

    obit  = json->stack_end_bit;

    if (obit == 0) {

       if (obyte == 0)

           return -1;

        --obyte;

        obit = CHAR_BIT - 1;

    } else {

        --obit;

    }

    return (json->stack[obyte] & (1U << obit)) != 0;

}

/*

 * OSSL_JSON_ENC: Initialisation

 * =============================

 */

enum {

    STATE_PRE_KEY,

    STATE_PRE_ITEM,

    STATE_PRE_COMMA

};

static ossl_inline int in_ijson(const OSSL_JSON_ENC *json)

{

    return (json->flags & OSSL_JSON_FLAG_IJSON) != 0;

}

static ossl_inline int in_seq(const OSSL_JSON_ENC *json)

{

    return (json->flags & OSSL_JSON_FLAG_SEQ) != 0;

}

static ossl_inline int in_pretty(const OSSL_JSON_ENC *json)

{

    return (json->flags & OSSL_JSON_FLAG_PRETTY) != 0;

}

int ossl_json_init(OSSL_JSON_ENC *json, BIO *bio, uint32_t flags)

{

    memset(json, 0, sizeof(*json));

    json->flags     = flags;

    json->error     = 0;

    if (!wbuf_init(&json->wbuf, bio, 4096))

        return 0;

    json->state = STATE_PRE_COMMA;

    return 1;

}

void ossl_json_cleanup(OSSL_JSON_ENC *json)

{

    wbuf_cleanup(&json->wbuf);

    if (json->stack != json->stack_small)

        OPENSSL_free(json->stack);

    json->stack = NULL;

}

int ossl_json_flush_cleanup(OSSL_JSON_ENC *json)

{

    int ok = ossl_json_flush(json);

    ossl_json_cleanup(json);

    return ok;

}

int ossl_json_reset(OSSL_JSON_ENC *json)

{

    wbuf_clean(&json->wbuf);

    json->stack_end_byte    = 0;

    json->stack_end_bit     = 0;

    json->error             = 0;

    return 1;

}

int ossl_json_flush(OSSL_JSON_ENC *json)

{

    return wbuf_flush(&json->wbuf, /*full=*/1);

}

int ossl_json_set0_sink(OSSL_JSON_ENC *json, BIO *bio)

{

    wbuf_set0_bio(&json->wbuf, bio);

    return 1;

}

int ossl_json_in_error(OSSL_JSON_ENC *json)

{

    return json->error;

}

/*

 * JSON Builder Calls

 * ==================

 */

static void json_write_qstring(OSSL_JSON_ENC *json, const char *str);

static void json_indent(OSSL_JSON_ENC *json);

static void json_raise_error(OSSL_JSON_ENC *json)

{

    json->error = 1;

}

static void json_undefer(OSSL_JSON_ENC *json)

{

    if (!json->defer_indent)

        return;

    json_indent(json);

}

static void json_write_char(OSSL_JSON_ENC *json, char ch)

{

    if (ossl_json_in_error(json))

        return;

    json_undefer(json);

    if (!wbuf_write_char(&json->wbuf, ch))

        json_raise_error(json);

}

static void json_write_str(OSSL_JSON_ENC *json, const char *s)

{

    if (ossl_json_in_error(json))

        return;

    json_undefer(json);

    if (!wbuf_write_str(&json->wbuf, s))

        json_raise_error(json);

}

static void json_indent(OSSL_JSON_ENC *json)

{

    size_t i, depth;

    json->defer_indent = 0;

    if (!in_pretty(json))

        return;

    json_write_char(json, '\n');

    depth = json->stack_end_byte * 8 + json->stack_end_bit;

    for (i = 0; i < depth * 4; ++i)

        json_write_str(json, "    ");

}

static int json_pre_item(OSSL_JSON_ENC *json)

{

    int s;

    if (ossl_json_in_error(json))

        return 0;

    switch (json->state) {

    case STATE_PRE_COMMA:

        s = json_peek(json);

        if (s == 0) {

            json_raise_error(json);

            return 0;

        }

        if (s == 1) {

            json_write_char(json, ',');

            if (ossl_json_in_error(json))

                return 0;

            json_indent(json);

        }

        if (s < 0 && in_seq(json))

            json_write_char(json, '\x1E');

        json->state = STATE_PRE_ITEM;

        break;

    case STATE_PRE_ITEM:

        break;

    case STATE_PRE_KEY:

    default:

        json_raise_error(json);

        return 0;

    }

    return 1;

}

static void json_post_item(OSSL_JSON_ENC *json)

{

    int s = json_peek(json);

    json->state = STATE_PRE_COMMA;

    if (s < 0 && in_seq(json))

        json_write_char(json, '\n');

}

/*

 * Begin a composite structure (object or array).

 *

 * type: 0=object, 1=array.

 */

static void composite_begin(OSSL_JSON_ENC *json, int type, char ch)

{

    if (!json_pre_item(json)

        || !json_push(json, type))

        json_raise_error(json);

    json_write_char(json, ch);

    json->defer_indent = 1;

}

/*

 * End a composite structure (object or array).

 *

 * type: 0=object, 1=array. Errors on mismatch.

 */

static void composite_end(OSSL_JSON_ENC *json, int type, char ch)

{

    int was_defer = json->defer_indent;

    if (ossl_json_in_error(json))

        return;

    json->defer_indent = 0;

    if (json_peek(json) != type) {

        json_raise_error(json);

        return;

    }

    if (type == 0 && json->state == STATE_PRE_ITEM) {

        json_raise_error(json);

        return;

    }

    if (!json_pop(json)) {

        json_raise_error(json);

        return;

    }

    if (!was_defer)

        json_indent(json);

    json_write_char(json, ch);

    json_post_item(json);

}

/* Begin a new JSON object. */

void ossl_json_object_begin(OSSL_JSON_ENC *json)

{

    composite_begin(json, 0, '{');

    json->state = STATE_PRE_KEY;

}

/* End a JSON object. Must be matched with a call to ossl_json_object_begin(). */

void ossl_json_object_end(OSSL_JSON_ENC *json)

{

    composite_end(json, 0, '}');

}

/* Begin a new JSON array. */

void ossl_json_array_begin(OSSL_JSON_ENC *json)

{

    composite_begin(json, 1, '[');

    json->state = STATE_PRE_ITEM;

}

/* End a JSON array. Must be matched with a call to ossl_json_array_begin(). */

void ossl_json_array_end(OSSL_JSON_ENC *json)

{

    composite_end(json, 1, ']');

}

/*

 * Encode a JSON key within an object. Pass a zero-terminated string, which can

 * be freed immediately following the call to this function.

 */

void ossl_json_key(OSSL_JSON_ENC *json, const char *key)

{

    if (ossl_json_in_error(json))

        return;

    if (json_peek(json) != 0) {

        /* Not in object */

        json_raise_error(json);

        return;

    }

    if (json->state == STATE_PRE_COMMA) {

        json_write_char(json, ',');

        json->state = STATE_PRE_KEY;

    }

    json_indent(json);

    if (json->state != STATE_PRE_KEY) {

        json_raise_error(json);

        return;

    }

    json_write_qstring(json, key);

    if (ossl_json_in_error(json))

        return;

    json_write_char(json, ':');

    if (in_pretty(json))

        json_write_char(json, ' ');

    json->state = STATE_PRE_ITEM;

}

/* Encode a JSON 'null' value. */

void ossl_json_null(OSSL_JSON_ENC *json)

{

    if (!json_pre_item(json))

        return;

    json_write_str(json, "null");

    json_post_item(json);

}

void ossl_json_bool(OSSL_JSON_ENC *json, bool v)

{

    if (!json_pre_item(json))

        return;

    json_write_str(json, v ? "true" : "false");

    json_post_item(json);

}

#define POW_53 (((int64_t)1) << 53)

/* Encode a JSON integer from a uint64_t. */

static void json_u64(OSSL_JSON_ENC *json, uint64_t v, int noquote)

{

    char buf[22], *p = buf + sizeof(buf) - 1;

    int quote = !noquote && in_ijson(json) && v > (uint64_t)(POW_53 - 1);

    if (!json_pre_item(json))

        return;

    if (quote)

        json_write_char(json, '"');

    if (v == 0)

        p = "0";

    else

        for (*p = '\0'; v > 0; v /= 10)

            *--p = '0' + v % 10;

    json_write_str(json, p);

    if (quote)

        json_write_char(json, '"');

    json_post_item(json);

}

void ossl_json_u64(OSSL_JSON_ENC *json, uint64_t v)

{

    json_u64(json, v, 0);

}

/* Encode a JSON integer from an int64_t. */

void ossl_json_i64(OSSL_JSON_ENC *json, int64_t value)

{

    uint64_t uv;

    int quote;

    if (value >= 0) {

        ossl_json_u64(json, (uint64_t)value);

        return;

    }

    if (!json_pre_item(json))

        return;

    quote = in_ijson(json)

        && (value > POW_53 - 1 || value < -POW_53 + 1);

    if (quote)

        json_write_char(json, '"');

    json_write_char(json, '-');

    uv = (value == INT64_MIN)

        ? ((uint64_t)-(INT64_MIN + 1)) + 1

        : (uint64_t)-value;

    json_u64(json, uv, /*noquote=*/1);

    if (quote && !ossl_json_in_error(json))

        json_write_char(json, '"');

}

/*

 * Encode a JSON UTF-8 string from a zero-terminated string. The string passed

 * can be freed immediately following the call to this function.

 */

static ossl_inline int hex_digit(int v)

{

    return v >= 10 ? 'a' + (v - 10) : '0' + v;

}

static ossl_inline void

json_write_qstring_inner(OSSL_JSON_ENC *json, const char *str, size_t str_len,

                         int nul_term)

{

    char c, *o, obuf[7];

    unsigned char *u_str;

    int i;

    size_t j;

    if (ossl_json_in_error(json))

        return;

    json_write_char(json, '"');

    for (j = nul_term ? strlen(str) : str_len; j > 0; str++, j--) {

        c = *str;

        u_str = (unsigned char*)str;

        switch (c) {

        case '\n': o = "\\n"; break;

        case '\r': o = "\\r"; break;

        case '\t': o = "\\t"; break;

        case '\b': o = "\\b"; break;

        case '\f': o = "\\f"; break;

        case '"': o = "\\\""; break;

        case '\\': o = "\\\\"; break;

        default:

            /* valid UTF-8 sequences according to RFC-3629 */

            if (u_str[0] >= 0xc2 && u_str[0] <= 0xdf && j >= 2

                    && u_str[1] >= 0x80 && u_str[1] <= 0xbf) {

                memcpy(obuf, str, 2);

                obuf[2] = '\0';

                str++, j--;

                o = obuf;

                break;

            }

            if (u_str[0] >= 0xe0 && u_str[0] <= 0xef && j >= 3

                    && u_str[1] >= 0x80 && u_str[1] <= 0xbf

                    && u_str[2] >= 0x80 && u_str[2] <= 0xbf

                    && !(u_str[0] == 0xe0 && u_str[1] <= 0x9f)

                    && !(u_str[0] == 0xed && u_str[1] >= 0xa0)) {

                memcpy(obuf, str, 3);

                obuf[3] = '\0';

                str += 2;

                j -= 2;

                o = obuf;

                break;

            }

            if (u_str[0] >= 0xf0 && u_str[0] <= 0xf4 && j >= 4

                    && u_str[1] >= 0x80 && u_str[1] <= 0xbf

                    && u_str[2] >= 0x80 && u_str[2] <= 0xbf

                    && u_str[3] >= 0x80 && u_str[3] <= 0xbf

                    && !(u_str[0] == 0xf0 && u_str[1] <= 0x8f)

                    && !(u_str[0] == 0xf4 && u_str[1] >= 0x90)) {

                memcpy(obuf, str, 4);

                obuf[4] = '\0';

                str += 3;

                j -= 3;

                o = obuf;

                break;

            }

            if (u_str[0] < 0x20 || u_str[0] >= 0x7f) {

                obuf[0] = '\\';

                obuf[1] = 'u';

                for (i = 0; i < 4; ++i)

                    obuf[2 + i] = hex_digit((u_str[0] >> ((3 - i) * 4)) & 0x0F);

                obuf[6] = '\0';

                o = obuf;

            } else {

                json_write_char(json, c);

                continue;

            }

            break;

        }

        json_write_str(json, o);

    }

    json_write_char(json, '"');

}

static void

json_write_qstring(OSSL_JSON_ENC *json, const char *str)

{

    json_write_qstring_inner(json, str, 0, 1);

}

static void

json_write_qstring_len(OSSL_JSON_ENC *json, const char *str, size_t str_len)

{

    json_write_qstring_inner(json, str, str_len, 0);

}

void ossl_json_str(OSSL_JSON_ENC *json, const char *str)

{

    if (!json_pre_item(json))

        return;

    json_write_qstring(json, str);

    json_post_item(json);

}

void ossl_json_str_len(OSSL_JSON_ENC *json, const char *str, size_t str_len)

{

    if (!json_pre_item(json))

        return;

    json_write_qstring_len(json, str, str_len);

    json_post_item(json);

}

/*

 * Encode binary data as a lowercase hex string. data_len is the data length in

 * bytes.

 */

void ossl_json_str_hex(OSSL_JSON_ENC *json, const void *data, size_t data_len)

{

    const unsigned char *b = data, *end = b + data_len;

    unsigned char c;

    if (!json_pre_item(json))

        return;

    json_write_char(json, '"');

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

        c = *b;

        json_write_char(json, hex_digit(c >> 4));

        json_write_char(json, hex_digit(c & 0x0F));

    }

    json_write_char(json, '"');

    json_post_item(json);

}