/* tls13_memio.c
 *
 * Copyright (C) 2006-2026 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

/* Self-contained TLS 1.3 handshake over an in-memory transport.
 *
 * Single process, no sockets, no threads (SINGLE_THREADED safe): the client
 * and server WOLFSSL objects are wired together through two in-memory byte
 * queues, and the handshake is driven to completion in one loop. It exercises
 * the real TLS 1.3 handshake state machine for builds where the example/unit
 * test harness is not available, e.g. a minimal --disable-examples build.
 *
 * By default it runs the minimal PSK + ECDHE handshake (no X.509). On a cert
 * build (WOLFSSL_TINY_TLS13_CERT) it runs a certificate handshake instead: the
 * server presents an ECDSA P-256 certificate and the client validates it,
 * driving the Certificate / CertificateVerify path. Cert files default to
 * ../certs (the layout used by parallel-make-check.py builds); override the
 * CERT_DIR macro at build time to point elsewhere.
 *
 * Build against a static build and run:
 *   cc -I<build> -I<src> tls13_memio.c <build>/src/.libs/libwolfssl.a -lm \
 *      -o tls13_memio && ./tls13_memio
 */

#ifndef WOLFSSL_USER_SETTINGS
    #include <wolfssl/options.h>
#endif
#include <wolfssl/ssl.h>

#include <string.h>
#include <stdio.h>

/* In-memory transport buffer; must hold one handshake flight. Build-time override. */
#ifndef MEM_BUF_SZ
#define MEM_BUF_SZ 32768
#endif

/* Max connect/accept round trips to drive the handshake. Build-time override. */
#ifndef HS_MAX_ITERS
#define HS_MAX_ITERS 50
#endif

#ifndef WOLFSSL_TINY_TLS13_CERT
/* Example-only fixed test PSK and identity shared by both endpoints; not a
 * real secret. Provision your own for anything beyond this smoke test. */
static const unsigned char psk_key[16] = {
    0x1a, 0x2b, 0x3c, 0x4d, 0x5e, 0x6f, 0x70, 0x81,
    0x92, 0xa3, 0xb4, 0xc5, 0xd6, 0xe7, 0xf8, 0x09
};
static const char psk_identity[] = "tinytls13-client";
#endif /* !WOLFSSL_TINY_TLS13_CERT */

typedef struct membuf {
    unsigned char data[MEM_BUF_SZ];
    int len;
} membuf;

/* recv: drain from the queue this endpoint reads from */
static int mem_recv(WOLFSSL* ssl, char* buf, int sz, void* ctx)
{
    membuf* mb = (membuf*)ctx;
    int n;

    (void)ssl;
    if (mb->len == 0)
        return WOLFSSL_CBIO_ERR_WANT_READ;
    n = (sz < mb->len) ? sz : mb->len;
    XMEMCPY(buf, mb->data, (size_t)n);
    XMEMMOVE(mb->data, mb->data + n, (size_t)(mb->len - n));
    mb->len -= n;
    return n;
}

/* send: append to the queue the peer reads from */
static int mem_send(WOLFSSL* ssl, char* buf, int sz, void* ctx)
{
    membuf* mb = (membuf*)ctx;

    (void)ssl;
    if (sz < 0 || mb->len > MEM_BUF_SZ - sz)
        return WOLFSSL_CBIO_ERR_WANT_WRITE;
    XMEMCPY(mb->data + mb->len, buf, (size_t)sz);
    mb->len += sz;
    return sz;
}

#ifndef WOLFSSL_TINY_TLS13_CERT
static unsigned int psk_client_cb(WOLFSSL* ssl, const char* hint,
    char* identity, unsigned int id_max, unsigned char* key,
    unsigned int key_max)
{
    (void)ssl;
    (void)hint;
    if (id_max < sizeof(psk_identity) || key_max < sizeof(psk_key))
        return 0;
    XMEMCPY(identity, psk_identity, sizeof(psk_identity));
    XMEMCPY(key, psk_key, sizeof(psk_key));
    return (unsigned int)sizeof(psk_key);
}

static unsigned int psk_server_cb(WOLFSSL* ssl, const char* identity,
    unsigned char* key, unsigned int key_max)
{
    (void)ssl;
    (void)identity;
    if (key_max < sizeof(psk_key))
        return 0;
    XMEMCPY(key, psk_key, sizeof(psk_key));
    return (unsigned int)sizeof(psk_key);
}
#endif /* !WOLFSSL_TINY_TLS13_CERT */

#ifdef WOLFSSL_TINY_TLS13_CERT
/* Build-time override to point at a different certs tree. */
#ifndef CERT_DIR
#define CERT_DIR "../certs"
#endif
#if defined(WOLFSSL_HAVE_MLDSA)
    #define SERVER_CERT_FILE CERT_DIR "/mldsa/ecc-leaf-mldsa44.pem"
    #define CLIENT_CA_FILE   CERT_DIR "/mldsa/mldsa44-cert.pem"
#elif defined(WOLFSSL_TINY_TLS13_RSA_VERIFY)
    #define SERVER_CERT_FILE CERT_DIR "/rsapss/ecc-leaf-rsapss.pem"
    #define CLIENT_CA_FILE   CERT_DIR "/rsapss/ca-rsapss.pem"
#else
    #define SERVER_CERT_FILE CERT_DIR "/server-ecc.pem"
    #define CLIENT_CA_FILE   CERT_DIR "/ca-ecc-cert.pem"
#endif
#define SERVER_KEY_FILE CERT_DIR "/ecc-key.pem"
#endif /* WOLFSSL_TINY_TLS13_CERT */

int main(int argc, char** argv)
{
    WOLFSSL_CTX* cctx = NULL;
    WOLFSSL_CTX* sctx = NULL;
    WOLFSSL* c = NULL;
    WOLFSSL* s = NULL;
    membuf c2s; /* client writes, server reads */
    membuf s2c; /* server writes, client reads */
    int i, cdone = 0, sdone = 0, ret = 1;
    int cret = WC_NO_ERR_TRACE(WOLFSSL_FATAL_ERROR);
    int sret = WC_NO_ERR_TRACE(WOLFSSL_FATAL_ERROR);
    const char* cipher = (argc > 1) ? argv[1] : "-";
    const char* group  = (argc > 2) ? argv[2] : "-";
    int mlkemGroup[1];

    XMEMSET(&c2s, 0, sizeof(c2s));
    XMEMSET(&s2c, 0, sizeof(s2c));

    wolfSSL_Init();

    cctx = wolfSSL_CTX_new(wolfTLSv1_3_client_method());
    sctx = wolfSSL_CTX_new(wolfTLSv1_3_server_method());
    if (cctx == NULL || sctx == NULL) {
        printf("smoke: CTX_new failed\n");
        goto done;
    }

    /* Force a specific suite when asked, so an adder config proves its cipher
     * negotiates: a single-suite list means a completed handshake used it. */
    if (cipher[0] != '\0' && cipher[0] != '-') {
        wolfSSL_CTX_set_cipher_list(cctx, cipher);
        wolfSSL_CTX_set_cipher_list(sctx, cipher);
    }

#ifdef WOLFSSL_TINY_TLS13_CERT
    /* Server presents an ECDSA leaf signed by the CA whose algorithm this
     * profile verifies (ECDSA, ML-DSA-44, or RSA-PSS); a completed handshake
     * drives that verify path. */
    if (wolfSSL_CTX_use_certificate_file(sctx, SERVER_CERT_FILE,
            WOLFSSL_FILETYPE_PEM) != WOLFSSL_SUCCESS ||
        wolfSSL_CTX_use_PrivateKey_file(sctx, SERVER_KEY_FILE,
            WOLFSSL_FILETYPE_PEM) != WOLFSSL_SUCCESS ||
        wolfSSL_CTX_load_verify_locations(cctx, CLIENT_CA_FILE, NULL)
            != WOLFSSL_SUCCESS) {
        printf("smoke: cert load failed (dir=%s)\n", CERT_DIR);
        goto done;
    }
#else
    wolfSSL_CTX_set_psk_client_callback(cctx, psk_client_cb);
    wolfSSL_CTX_set_psk_server_callback(sctx, psk_server_cb);
#endif

    wolfSSL_CTX_SetIORecv(cctx, mem_recv);
    wolfSSL_CTX_SetIOSend(cctx, mem_send);
    wolfSSL_CTX_SetIORecv(sctx, mem_recv);
    wolfSSL_CTX_SetIOSend(sctx, mem_send);

    c = wolfSSL_new(cctx);
    s = wolfSSL_new(sctx);
    if (c == NULL || s == NULL) {
        printf("smoke: SSL_new failed\n");
        goto done;
    }

    /* Restrict to the ML-KEM hybrid key share when asked, so a completed
     * handshake proves the hybrid KEX was negotiated. */
    if (XSTRCMP(group, "mlkem") == 0) {
        mlkemGroup[0] = WOLFSSL_X25519MLKEM768;
        wolfSSL_set_groups(c, mlkemGroup, 1);
        wolfSSL_set_groups(s, mlkemGroup, 1);
    }

    /* client reads s2c, writes c2s; server reads c2s, writes s2c */
    wolfSSL_SetIOReadCtx(c, &s2c);
    wolfSSL_SetIOWriteCtx(c, &c2s);
    wolfSSL_SetIOReadCtx(s, &c2s);
    wolfSSL_SetIOWriteCtx(s, &s2c);

    for (i = 0; i < HS_MAX_ITERS && !(cdone && sdone); i++) {
        if (!cdone) {
            cret = wolfSSL_connect(c);
            if (cret == WOLFSSL_SUCCESS)
                cdone = 1;
        }
        if (!sdone) {
            sret = wolfSSL_accept(s);
            if (sret == WOLFSSL_SUCCESS)
                sdone = 1;
        }
    }

    if (cdone && sdone &&
            XSTRCMP(wolfSSL_get_version(c), "TLSv1.3") == 0) {
        printf("tls13_memio handshake OK: %s %s\n",
            wolfSSL_get_version(c), wolfSSL_get_cipher(c));
        ret = 0;
    }
    else {
        printf("tls13_memio handshake FAILED (client err %d, server err %d)\n",
            wolfSSL_get_error(c, cret), wolfSSL_get_error(s, sret));
    }

done:
    wolfSSL_free(c);
    wolfSSL_free(s);
    wolfSSL_CTX_free(cctx);
    wolfSSL_CTX_free(sctx);
    wolfSSL_Cleanup();
    return ret;
}