/*

 * Copyright 2015-2025 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/cryptlib.h"

#include "internal/packet.h"

#if !defined OPENSSL_NO_QUIC && !defined FIPS_MODULE

#include "internal/packet_quic.h"

#endif

#include <openssl/err.h>

#define DEFAULT_BUF_SIZE 256

int WPACKET_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)

{

    if (!WPACKET_reserve_bytes(pkt, len, allocbytes))

        return 0;

    pkt->written += len;

    pkt->curr += len;

    return 1;

}

int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len,

    unsigned char **allocbytes, size_t lenbytes)

{

    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)

        || !WPACKET_allocate_bytes(pkt, len, allocbytes)

        || !WPACKET_close(pkt))

        return 0;

    return 1;

}

#define GETBUF(p) (((p)->staticbuf != NULL)         \

        ? (p)->staticbuf                            \

        : ((p)->buf != NULL                         \

                  ? (unsigned char *)(p)->buf->data \

                  : NULL))

int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(pkt->subs != NULL && len != 0))

        return 0;

    if (pkt->maxsize - pkt->written < len)

        return 0;

    if (pkt->buf != NULL && (pkt->buf->length - pkt->written < len)) {

        size_t newlen;

        size_t reflen;

        reflen = (len > pkt->buf->length) ? len : pkt->buf->length;

        if (reflen > SIZE_MAX / 2) {

            newlen = SIZE_MAX;

        } else {

            newlen = reflen * 2;

            if (newlen < DEFAULT_BUF_SIZE)

                newlen = DEFAULT_BUF_SIZE;

        }

        if (BUF_MEM_grow(pkt->buf, newlen) == 0)

            return 0;

    }

    if (allocbytes != NULL) {

        *allocbytes = WPACKET_get_curr(pkt);

        if (pkt->endfirst && *allocbytes != NULL)

            *allocbytes -= len;

    }

    return 1;

}

int WPACKET_sub_reserve_bytes__(WPACKET *pkt, size_t len,

    unsigned char **allocbytes, size_t lenbytes)

{

    if (pkt->endfirst && lenbytes > 0)

        return 0;

    if (!WPACKET_reserve_bytes(pkt, lenbytes + len, allocbytes))

        return 0;

    if (*allocbytes != NULL)

        *allocbytes += lenbytes;

    return 1;

}

static size_t maxmaxsize(size_t lenbytes)

{

    if (lenbytes >= sizeof(size_t) || lenbytes == 0)

        return SIZE_MAX;

    return ((size_t)1 << (lenbytes * 8)) - 1 + lenbytes;

}

static int wpacket_intern_init_len(WPACKET *pkt, size_t lenbytes)

{

    unsigned char *lenchars;

    pkt->curr = 0;

    pkt->written = 0;

    if ((pkt->subs = OPENSSL_zalloc(sizeof(*pkt->subs))) == NULL)

        return 0;

    if (lenbytes == 0)

        return 1;

    pkt->subs->pwritten = lenbytes;

    pkt->subs->lenbytes = lenbytes;

    if (!WPACKET_allocate_bytes(pkt, lenbytes, &lenchars)) {

        OPENSSL_free(pkt->subs);

        pkt->subs = NULL;

        return 0;

    }

    pkt->subs->packet_len = 0;

    return 1;

}

int WPACKET_init_static_len(WPACKET *pkt, unsigned char *buf, size_t len,

    size_t lenbytes)

{

    size_t max = maxmaxsize(lenbytes);

    /* Internal API, so should not fail */

    if (!ossl_assert(buf != NULL && len > 0))

        return 0;

    pkt->staticbuf = buf;

    pkt->buf = NULL;

    pkt->maxsize = (max < len) ? max : len;

    pkt->endfirst = 0;

    return wpacket_intern_init_len(pkt, lenbytes);

}

int WPACKET_init_der(WPACKET *pkt, unsigned char *buf, size_t len)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(buf != NULL && len > 0))

        return 0;

    pkt->staticbuf = buf;

    pkt->buf = NULL;

    pkt->maxsize = len;

    pkt->endfirst = 1;

    return wpacket_intern_init_len(pkt, 0);

}

int WPACKET_init_len(WPACKET *pkt, BUF_MEM *buf, size_t lenbytes)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(buf != NULL))

        return 0;

    pkt->staticbuf = NULL;

    pkt->buf = buf;

    pkt->maxsize = maxmaxsize(lenbytes);

    pkt->endfirst = 0;

    return wpacket_intern_init_len(pkt, lenbytes);

}

int WPACKET_init(WPACKET *pkt, BUF_MEM *buf)

{

    return WPACKET_init_len(pkt, buf, 0);

}

int WPACKET_init_null(WPACKET *pkt, size_t lenbytes)

{

    pkt->staticbuf = NULL;

    pkt->buf = NULL;

    pkt->maxsize = maxmaxsize(lenbytes);

    pkt->endfirst = 0;

    return wpacket_intern_init_len(pkt, 0);

}

int WPACKET_init_null_der(WPACKET *pkt)

{

    pkt->staticbuf = NULL;

    pkt->buf = NULL;

    pkt->maxsize = SIZE_MAX;

    pkt->endfirst = 1;

    return wpacket_intern_init_len(pkt, 0);

}

int WPACKET_set_flags(WPACKET *pkt, unsigned int flags)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(pkt->subs != NULL))

        return 0;

    pkt->subs->flags = flags;

    return 1;

}

/* Store the |value| of length |len| at location |data| */

static int put_value(unsigned char *data, uint64_t value, size_t len)

{

    if (data == NULL)

        return 1;

    for (data += len - 1; len > 0; len--) {

        *data = (unsigned char)(value & 0xff);

        data--;

        value >>= 8;

    }

    /* Check whether we could fit the value in the assigned number of bytes */

    if (value > 0)

        return 0;

    return 1;

}

#if !defined OPENSSL_NO_QUIC && !defined FIPS_MODULE

static int put_quic_value(unsigned char *data, size_t value, size_t len)

{

    if (data == NULL)

        return 1;

    /* Value too large for field. */

    if (ossl_quic_vlint_encode_len(value) > len)

        return 0;

    ossl_quic_vlint_encode_n(data, value, (int)len);

    return 1;

}

#endif

/*

 * Internal helper function used by WPACKET_close(), WPACKET_finish() and

 * WPACKET_fill_lengths() to close a sub-packet and write out its length if

 * necessary. If |doclose| is 0 then it goes through the motions of closing

 * (i.e. it fills in all the lengths), but doesn't actually close anything.

 */

static int wpacket_intern_close(WPACKET *pkt, WPACKET_SUB *sub, int doclose)

{

    size_t packlen = pkt->written - sub->pwritten;

    if (packlen == 0

        && (sub->flags & WPACKET_FLAGS_NON_ZERO_LENGTH) != 0)

        return 0;

    if (packlen == 0

        && sub->flags & WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH) {

        /* We can't handle this case. Return an error */

        if (!doclose)

            return 0;

        /* Deallocate any bytes allocated for the length of the WPACKET */

        if ((pkt->curr - sub->lenbytes) == sub->packet_len) {

            pkt->written -= sub->lenbytes;

            pkt->curr -= sub->lenbytes;

        }

        /* Don't write out the packet length */

        sub->packet_len = 0;

        sub->lenbytes = 0;

    }

    /* Write out the WPACKET length if needed */

    if (sub->lenbytes > 0) {

        unsigned char *buf = GETBUF(pkt);

        if (buf != NULL) {

#if !defined OPENSSL_NO_QUIC && !defined FIPS_MODULE

            if ((sub->flags & WPACKET_FLAGS_QUIC_VLINT) == 0) {

                if (!put_value(&buf[sub->packet_len], packlen, sub->lenbytes))

                    return 0;

            } else {

                if (!put_quic_value(&buf[sub->packet_len], packlen, sub->lenbytes))

                    return 0;

            }

#else

            if (!put_value(&buf[sub->packet_len], packlen, sub->lenbytes))

                return 0;

#endif

        }

    } else if (pkt->endfirst && sub->parent != NULL

        && (packlen != 0

            || (sub->flags

                   & WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH)

                == 0)) {

        size_t tmplen = packlen;

        size_t numlenbytes = 1;

        while ((tmplen = tmplen >> 8) > 0)

            numlenbytes++;

        if (!WPACKET_put_bytes__(pkt, packlen, numlenbytes))

            return 0;

        if (packlen > 0x7f) {

            numlenbytes |= 0x80;

            if (!WPACKET_put_bytes_u8(pkt, numlenbytes))

                return 0;

        }

    }

    if (doclose) {

        pkt->subs = sub->parent;

        OPENSSL_free(sub);

    }

    return 1;

}

int WPACKET_fill_lengths(WPACKET *pkt)

{

    WPACKET_SUB *sub;

    if (!ossl_assert(pkt->subs != NULL))

        return 0;

    for (sub = pkt->subs; sub != NULL; sub = sub->parent) {

        if (!wpacket_intern_close(pkt, sub, 0))

            return 0;

    }

    return 1;

}

int WPACKET_close(WPACKET *pkt)

{

    /*

     * Internal API, so should not fail - but we do negative testing of this

     * so no assert (otherwise the tests fail)

     */

    if (pkt->subs == NULL || pkt->subs->parent == NULL)

        return 0;

    return wpacket_intern_close(pkt, pkt->subs, 1);

}

int WPACKET_finish(WPACKET *pkt)

{

    int ret;

    /*

     * Internal API, so should not fail - but we do negative testing of this

     * so no assert (otherwise the tests fail)

     */

    if (pkt->subs == NULL || pkt->subs->parent != NULL)

        return 0;

    ret = wpacket_intern_close(pkt, pkt->subs, 1);

    if (ret) {

        OPENSSL_free(pkt->subs);

        pkt->subs = NULL;

    }

    return ret;

}

int WPACKET_start_sub_packet_len__(WPACKET *pkt, size_t lenbytes)

{

    WPACKET_SUB *sub;

    unsigned char *lenchars;

    /* Internal API, so should not fail */

    if (!ossl_assert(pkt->subs != NULL))

        return 0;

    /* We don't support lenbytes greater than 0 when doing endfirst writing */

    if (lenbytes > 0 && pkt->endfirst)

        return 0;

    if ((sub = OPENSSL_zalloc(sizeof(*sub))) == NULL)

        return 0;

    sub->parent = pkt->subs;

    pkt->subs = sub;

    sub->pwritten = pkt->written + lenbytes;

    sub->lenbytes = lenbytes;

    if (lenbytes == 0) {

        sub->packet_len = 0;

        return 1;

    }

    sub->packet_len = pkt->written;

    if (!WPACKET_allocate_bytes(pkt, lenbytes, &lenchars))

        return 0;

    return 1;

}

int WPACKET_start_sub_packet(WPACKET *pkt)

{

    return WPACKET_start_sub_packet_len__(pkt, 0);

}

int WPACKET_put_bytes__(WPACKET *pkt, uint64_t val, size_t size)

{

    unsigned char *data;

    /* Internal API, so should not fail */

    if (!ossl_assert(size <= sizeof(uint64_t))

        || !WPACKET_allocate_bytes(pkt, size, &data)

        || !put_value(data, val, size))

        return 0;

    return 1;

}

int WPACKET_set_max_size(WPACKET *pkt, size_t maxsize)

{

    WPACKET_SUB *sub;

    size_t lenbytes;

    /* Internal API, so should not fail */

    if (!ossl_assert(pkt->subs != NULL))

        return 0;

    /* Find the WPACKET_SUB for the top level */

    for (sub = pkt->subs; sub->parent != NULL; sub = sub->parent)

        continue;

    lenbytes = sub->lenbytes;

    if (lenbytes == 0)

        lenbytes = sizeof(pkt->maxsize);

    if (maxmaxsize(lenbytes) < maxsize || maxsize < pkt->written)

        return 0;

    pkt->maxsize = maxsize;

    return 1;

}

int WPACKET_memset(WPACKET *pkt, int ch, size_t len)

{

    unsigned char *dest;

    if (len == 0)

        return 1;

    if (!WPACKET_allocate_bytes(pkt, len, &dest))

        return 0;

    if (dest != NULL)

        memset(dest, ch, len);

    return 1;

}

int WPACKET_memcpy(WPACKET *pkt, const void *src, size_t len)

{

    unsigned char *dest;

    if (len == 0)

        return 1;

    if (!WPACKET_allocate_bytes(pkt, len, &dest))

        return 0;

    if (dest != NULL)

        memcpy(dest, src, len);

    return 1;

}

int WPACKET_sub_memcpy__(WPACKET *pkt, const void *src, size_t len,

    size_t lenbytes)

{

    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)

        || !WPACKET_memcpy(pkt, src, len)

        || !WPACKET_close(pkt))

        return 0;

    return 1;

}

int WPACKET_get_total_written(WPACKET *pkt, size_t *written)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(written != NULL))

        return 0;

    *written = pkt->written;

    return 1;

}

int WPACKET_get_length(WPACKET *pkt, size_t *len)

{

    /* Internal API, so should not fail */

    if (!ossl_assert(pkt->subs != NULL && len != NULL))

        return 0;

    *len = pkt->written - pkt->subs->pwritten;

    return 1;

}

unsigned char *WPACKET_get_curr(WPACKET *pkt)

{

    unsigned char *buf = GETBUF(pkt);

    if (buf == NULL)

        return NULL;

    if (pkt->endfirst)

        return buf + pkt->maxsize - pkt->curr;

    return buf + pkt->curr;

}

int WPACKET_is_null_buf(WPACKET *pkt)

{

    return pkt->buf == NULL && pkt->staticbuf == NULL;

}

void WPACKET_cleanup(WPACKET *pkt)

{

    WPACKET_SUB *sub, *parent;

    for (sub = pkt->subs; sub != NULL; sub = parent) {

        parent = sub->parent;

        OPENSSL_free(sub);

    }

    pkt->subs = NULL;

}

#if !defined OPENSSL_NO_QUIC && !defined FIPS_MODULE

int WPACKET_start_quic_sub_packet_bound(WPACKET *pkt, size_t max_len)

{

    size_t enclen = ossl_quic_vlint_encode_len(max_len);

    if (enclen == 0)

        return 0;

    if (WPACKET_start_sub_packet_len__(pkt, enclen) == 0)

        return 0;

    pkt->subs->flags |= WPACKET_FLAGS_QUIC_VLINT;

    return 1;

}

int WPACKET_start_quic_sub_packet(WPACKET *pkt)

{

    /*

     * Assume no (sub)packet will exceed 4GiB, thus the 8-byte encoding need not

     * be used.

     */

    return WPACKET_start_quic_sub_packet_bound(pkt, OSSL_QUIC_VLINT_4B_MIN);

}

int WPACKET_quic_sub_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)

{

    if (!WPACKET_start_quic_sub_packet_bound(pkt, len)

        || !WPACKET_allocate_bytes(pkt, len, allocbytes)

        || !WPACKET_close(pkt))

        return 0;

    return 1;

}

/*

 * Write a QUIC variable-length integer to the packet.

 */

int WPACKET_quic_write_vlint(WPACKET *pkt, uint64_t v)

{

    unsigned char *b = NULL;

    size_t enclen = ossl_quic_vlint_encode_len(v);

    if (enclen == 0)

        return 0;

    if (WPACKET_allocate_bytes(pkt, enclen, &b) == 0)

        return 0;

    ossl_quic_vlint_encode(b, v);

    return 1;

}

#endif