/*

 * Copyright 2025-2026 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 may obtain a copy of the License at

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

 * or in the file LICENSE in the source distribution.

 */

#include <openssl/ssl.h>

#include <openssl/err.h>

#include <openssl/bio.h>

#include "fuzzer.h"

#include "internal/sockets.h"

#include "internal/time.h"

#include "internal/quic_ssl.h"

static OSSL_TIME fake_now;

static OSSL_TIME fake_now_cb(void *arg)

{

    return fake_now;

}

int FuzzerInitialize(int *argc, char ***argv)

{

    STACK_OF(SSL_COMP) *comp_methods;

    FuzzerSetRand();

    OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS | OPENSSL_INIT_ASYNC, NULL);

    OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS, NULL);

    ERR_clear_error();

    CRYPTO_free_ex_index(0, -1);

    if (SSL_get_ex_data_X509_STORE_CTX_idx() == 0) {

        /* Just suppress warning */

    }

    comp_methods = SSL_COMP_get_compression_methods();

    if (comp_methods != NULL)

        sk_SSL_COMP_sort(comp_methods);

    return 1;

}

#define HANDSHAKING 0

#define READING 1

#define WRITING 2

#define ACCEPTING_STREAM 3

#define CREATING_STREAM 4

#define SWAPPING_STREAM 5

/*

 * This callback validates and negotiates the desired ALPN on the server side.

 * Accept any ALPN.

 */

static int select_alpn(SSL *ssl, const unsigned char **out,

    unsigned char *out_len, const unsigned char *in,

    unsigned int in_len, void *arg)

{

    return SSL_TLSEXT_ERR_OK;

}

int FuzzerTestOneInput(const uint8_t *buf, size_t len)

{

    SSL *server = NULL, *stream = NULL;

    SSL *allstreams[] = { NULL, NULL, NULL, NULL };

    size_t i, thisstream = 0, numstreams = 1;

    BIO *in;

    BIO *out;

    SSL_CTX *ctx;

    struct timeval tv;

    int state = HANDSHAKING;

    uint8_t tmp[1024];

    int writelen = 0;

    if (len == 0)

        return 0;

    ctx = SSL_CTX_new(OSSL_QUIC_server_method());

    if (ctx == NULL)

        goto end;

    SSL_CTX_set_alpn_select_cb(ctx, select_alpn, NULL);

    server = SSL_new_listener(ctx, 0);

    allstreams[0] = stream = server;

    if (server == NULL)

        goto end;

    fake_now = ossl_ms2time(1);

    if (!ossl_quic_set_override_now_cb(server, fake_now_cb, NULL))

        goto end;

    in = BIO_new(BIO_s_dgram_mem());

    if (in == NULL)

        goto end;

    out = BIO_new(BIO_s_dgram_mem());

    if (out == NULL) {

        BIO_free(in);

        goto end;

    }

    if (!BIO_dgram_set_caps(out, BIO_DGRAM_CAP_HANDLES_DST_ADDR)) {

        BIO_free(in);

        BIO_free(out);

        goto end;

    }

    SSL_set_bio(server, in, out);

    SSL_set_accept_state(server);

    for (;;) {

        size_t size;

        uint64_t nxtpktms = 0;

        OSSL_TIME nxtpkt = ossl_time_zero(), nxttimeout;

        int isinf, ret = 0;

        if (len >= 2) {

            if (len >= 5 && buf[0] == 0xff && buf[1] == 0xff) {

                switch (buf[2]) {

                case 0x00:

                    if (state == READING)

                        state = ACCEPTING_STREAM;

                    break;

                case 0x01:

                    if (state == READING)

                        state = CREATING_STREAM;

                    break;

                case 0x02:

                    if (state == READING)

                        state = SWAPPING_STREAM;

                    break;

                default:

                    /* ignore */

                    break;

                }

                len -= 3;

                buf += 3;

            }

            nxtpktms = buf[0] + (buf[1] << 8);

            nxtpkt = ossl_time_add(fake_now, ossl_ms2time(nxtpktms));

            len -= 2;

            buf += 2;

        }

        for (;;) {

            switch (state) {

            case HANDSHAKING:

                ret = SSL_accept_connection(stream, 0) != NULL;

                if (ret == 1)

                    state = READING;

                break;

            case READING:

                ret = SSL_read(stream, tmp, sizeof(tmp));

                if (ret > 0) {

                    state = WRITING;

                    writelen = ret;

                    assert(writelen <= (int)sizeof(tmp));

                }

                break;

            case WRITING:

                ret = SSL_write(stream, tmp, writelen);

                if (ret > 0)

                    state = READING;

                break;

            case ACCEPTING_STREAM:

                state = READING;

                ret = 1;

                if (numstreams == OSSL_NELEM(allstreams)

                    || SSL_get_accept_stream_queue_len(server) == 0)

                    break;

                thisstream = numstreams;

                stream = allstreams[numstreams++] = SSL_accept_stream(server, 0);

                if (stream == NULL)

                    goto end;

                break;

            case CREATING_STREAM:

                state = READING;

                ret = 1;

                if (numstreams == OSSL_NELEM(allstreams))

                    break;

                stream = SSL_new_stream(server, 0);

                if (stream == NULL) {

                    /* Ignore, and go back to the previous stream */

                    stream = allstreams[thisstream];

                    break;

                }

                thisstream = numstreams;

                allstreams[numstreams++] = stream;

                break;

            case SWAPPING_STREAM:

                state = READING;

                ret = 1;

                if (numstreams == 1)

                    break;

                if (++thisstream == numstreams)

                    thisstream = 0;

                stream = allstreams[thisstream];

                break;

            }

            assert(stream != NULL);

            assert(thisstream < numstreams);

            if (ret <= 0) {

                switch (SSL_get_error(stream, ret)) {

                case SSL_ERROR_WANT_READ:

                case SSL_ERROR_WANT_WRITE:

                    break;

                default:

                    goto end;

                }

            }

            if (!SSL_get_event_timeout(server, &tv, &isinf))

                goto end;

            if (isinf) {

                fake_now = nxtpkt;

                break;

            } else {

                nxttimeout = ossl_time_add(fake_now,

                    ossl_time_from_timeval(tv));

                if (len > 3 && ossl_time_compare(nxttimeout, nxtpkt) >= 0) {

                    fake_now = nxtpkt;

                    break;

                }

                fake_now = nxttimeout;

            }

        }

        if (len <= 3)

            break;

        size = buf[0] + (buf[1] << 8);

        if (size > len - 2)

            break;

        if (size > 0)

            BIO_write(in, buf + 2, (int)size);

        len -= size + 2;

        buf += size + 2;

    }

end:

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

        SSL_free(allstreams[i]);

    ERR_clear_error();

    SSL_CTX_free(ctx);

    return 0;

}

void FuzzerCleanup(void)

{

    FuzzerClearRand();

}