/*
 *  libratbox: a library used by ircd-ratbox and other things
 *  openssl.c: openssl related code
 *
 *  Copyright (C) 2007-2008 ircd-ratbox development team
 *  Copyright (C) 2007-2008 Aaron Sethman <androsyn@ratbox.org>
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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  02110-1301
 *  USA
 *
 */

#include <libratbox_config.h>
#include <ratbox_lib.h>

#ifdef HAVE_OPENSSL

#include <commio-int.h>
#include <commio-ssl.h>
#include <openssl/ssl.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/rand.h>

static SSL_CTX *ssl_server_ctx;
static SSL_CTX *ssl_client_ctx;
static int libratbox_index = -1;

static unsigned long
get_last_err(void)
{
    unsigned long t_err, err = 0;
    err = ERR_get_error();
    if(err == 0)
        return 0;

    while((t_err = ERR_get_error()) > 0)
        err = t_err;

    return err;
}

void
rb_ssl_shutdown(rb_fde_t *F)
{
    int i;
    if(F == NULL || F->ssl == NULL)
        return;
    SSL_set_shutdown((SSL *) F->ssl, SSL_RECEIVED_SHUTDOWN);

    for(i = 0; i < 4; i++) {
        if(SSL_shutdown((SSL *) F->ssl))
            break;
    }
    get_last_err();
    SSL_free((SSL *) F->ssl);
}

unsigned int
rb_ssl_handshake_count(rb_fde_t *F)
{
    return F->handshake_count;
}

void
rb_ssl_clear_handshake_count(rb_fde_t *F)
{
    F->handshake_count = 0;
}

static void
rb_ssl_timeout(rb_fde_t *F, void *notused)
{
    lrb_assert(F->accept != NULL);
    F->accept->callback(F, RB_ERR_TIMEOUT, NULL, 0, F->accept->data);
}


static void
rb_ssl_info_callback(SSL * ssl, int where, int ret)
{
    if(where & SSL_CB_HANDSHAKE_START) {
        rb_fde_t *F = SSL_get_ex_data(ssl, libratbox_index);
        if(F == NULL)
            return;
        F->handshake_count++;
    }
}

static void
rb_setup_ssl_cb(rb_fde_t *F)
{
    SSL_set_ex_data(F->ssl, libratbox_index, (char *)F);
    SSL_set_info_callback((SSL *) F->ssl, (void (*)(const SSL *,int,int))rb_ssl_info_callback);
}

static void
rb_ssl_tryaccept(rb_fde_t *F, void *data)
{
    int ssl_err;
    lrb_assert(F->accept != NULL);
    int flags;
    struct acceptdata *ad;

    if(!SSL_is_init_finished((SSL *) F->ssl)) {
        if((ssl_err = SSL_accept((SSL *) F->ssl)) <= 0) {
            switch (ssl_err = SSL_get_error((SSL *) F->ssl, ssl_err)) {
            case SSL_ERROR_WANT_READ:
            case SSL_ERROR_WANT_WRITE:
                if(ssl_err == SSL_ERROR_WANT_WRITE)
                    flags = RB_SELECT_WRITE;
                else
                    flags = RB_SELECT_READ;
                F->ssl_errno = get_last_err();
                rb_setselect(F, flags, rb_ssl_tryaccept, NULL);
                break;
            case SSL_ERROR_SYSCALL:
                F->accept->callback(F, RB_ERROR, NULL, 0, F->accept->data);
                break;
            default:
                F->ssl_errno = get_last_err();
                F->accept->callback(F, RB_ERROR_SSL, NULL, 0, F->accept->data);
                break;
            }
            return;
        }
    }
    rb_settimeout(F, 0, NULL, NULL);
    rb_setselect(F, RB_SELECT_READ | RB_SELECT_WRITE, NULL, NULL);

    ad = F->accept;
    F->accept = NULL;
    ad->callback(F, RB_OK, (struct sockaddr *)&ad->S, ad->addrlen, ad->data);
    rb_free(ad);

}


static void
rb_ssl_accept_common(rb_fde_t *new_F)
{
    int ssl_err;
    if((ssl_err = SSL_accept((SSL *) new_F->ssl)) <= 0) {
        switch (ssl_err = SSL_get_error((SSL *) new_F->ssl, ssl_err)) {
        case SSL_ERROR_SYSCALL:
            if(rb_ignore_errno(errno))
            case SSL_ERROR_WANT_READ:
        case SSL_ERROR_WANT_WRITE: {
            new_F->ssl_errno = get_last_err();
            rb_setselect(new_F, RB_SELECT_READ | RB_SELECT_WRITE,
                         rb_ssl_tryaccept, NULL);
            return;
        }
        default:
            new_F->ssl_errno = get_last_err();
            new_F->accept->callback(new_F, RB_ERROR_SSL, NULL, 0, new_F->accept->data);
            return;
        }
    } else {
        rb_ssl_tryaccept(new_F, NULL);
    }
}

void
rb_ssl_start_accepted(rb_fde_t *new_F, ACCB * cb, void *data, int timeout)
{
    new_F->type |= RB_FD_SSL;
    new_F->ssl = SSL_new(ssl_server_ctx);
    new_F->accept = rb_malloc(sizeof(struct acceptdata));

    new_F->accept->callback = cb;
    new_F->accept->data = data;
    rb_settimeout(new_F, timeout, rb_ssl_timeout, NULL);

    new_F->accept->addrlen = 0;
    SSL_set_fd((SSL *) new_F->ssl, rb_get_fd(new_F));
    rb_setup_ssl_cb(new_F);
    rb_ssl_accept_common(new_F);
}




void
rb_ssl_accept_setup(rb_fde_t *F, rb_fde_t *new_F, struct sockaddr *st, int addrlen)
{
    new_F->type |= RB_FD_SSL;
    new_F->ssl = SSL_new(ssl_server_ctx);
    new_F->accept = rb_malloc(sizeof(struct acceptdata));

    new_F->accept->callback = F->accept->callback;
    new_F->accept->data = F->accept->data;
    rb_settimeout(new_F, 10, rb_ssl_timeout, NULL);
    memcpy(&new_F->accept->S, st, addrlen);
    new_F->accept->addrlen = addrlen;

    SSL_set_fd((SSL *) new_F->ssl, rb_get_fd(new_F));
    rb_setup_ssl_cb(new_F);
    rb_ssl_accept_common(new_F);
}

static ssize_t
rb_ssl_read_or_write(int r_or_w, rb_fde_t *F, void *rbuf, const void *wbuf, size_t count)
{
    ssize_t ret;
    unsigned long err;
    SSL *ssl = F->ssl;

    if(r_or_w == 0)
        ret = (ssize_t) SSL_read(ssl, rbuf, (int)count);
    else
        ret = (ssize_t) SSL_write(ssl, wbuf, (int)count);

    if(ret < 0) {
        switch (SSL_get_error(ssl, ret)) {
        case SSL_ERROR_WANT_READ:
            errno = EAGAIN;
            return RB_RW_SSL_NEED_READ;
        case SSL_ERROR_WANT_WRITE:
            errno = EAGAIN;
            return RB_RW_SSL_NEED_WRITE;
        case SSL_ERROR_ZERO_RETURN:
            return 0;
        case SSL_ERROR_SYSCALL:
            err = get_last_err();
            if(err == 0) {
                F->ssl_errno = 0;
                return RB_RW_IO_ERROR;
            }
            break;
        default:
            err = get_last_err();
            break;
        }
        F->ssl_errno = err;
        if(err > 0) {
            errno = EIO;	/* not great but... */
            return RB_RW_SSL_ERROR;
        }
        return RB_RW_IO_ERROR;
    }
    return ret;
}

ssize_t
rb_ssl_read(rb_fde_t *F, void *buf, size_t count)
{
    return rb_ssl_read_or_write(0, F, buf, NULL, count);
}

ssize_t
rb_ssl_write(rb_fde_t *F, const void *buf, size_t count)
{
    return rb_ssl_read_or_write(1, F, NULL, buf, count);
}

static int
verify_accept_all_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
{
    return 1;
}

static const char *
get_ssl_error(unsigned long err)
{
    static char buf[512];

    ERR_error_string_n(err, buf, sizeof buf);
    return buf;
}

int
rb_init_ssl(void)
{
    int ret = 1;
    char libratbox_data[] = "libratbox data";
    SSL_load_error_strings();
    SSL_library_init();
    libratbox_index = SSL_get_ex_new_index(0, libratbox_data, NULL, NULL, NULL);
    ssl_server_ctx = SSL_CTX_new(SSLv23_server_method());
    if(ssl_server_ctx == NULL) {
        rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL server context: %s",
                   get_ssl_error(ERR_get_error()));
        ret = 0;
    }
    /* Disable SSLv2, make the client use our settings */
    SSL_CTX_set_options(ssl_server_ctx, SSL_OP_NO_SSLv2 | SSL_OP_CIPHER_SERVER_PREFERENCE);
    SSL_CTX_set_verify(ssl_server_ctx, SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, verify_accept_all_cb);

    ssl_client_ctx = SSL_CTX_new(TLSv1_client_method());

    if(ssl_client_ctx == NULL) {
        rb_lib_log("rb_init_openssl: Unable to initialize OpenSSL client context: %s",
                   get_ssl_error(ERR_get_error()));
        ret = 0;
    }
    return ret;
}


int
rb_setup_ssl_server(const char *cert, const char *keyfile, const char *dhfile)
{
    DH *dh;
    unsigned long err;
    if(cert == NULL) {
        rb_lib_log("rb_setup_ssl_server: No certificate file");
        return 0;
    }
    if(!SSL_CTX_use_certificate_chain_file(ssl_server_ctx, cert) || !SSL_CTX_use_certificate_chain_file(ssl_client_ctx, cert)) {
        err = ERR_get_error();
        rb_lib_log("rb_setup_ssl_server: Error loading certificate file [%s]: %s", cert,
                   get_ssl_error(err));
        return 0;
    }

    if(keyfile == NULL) {
        rb_lib_log("rb_setup_ssl_server: No key file");
        return 0;
    }


    if(!SSL_CTX_use_PrivateKey_file(ssl_server_ctx, keyfile, SSL_FILETYPE_PEM) || !SSL_CTX_use_PrivateKey_file(ssl_client_ctx, keyfile, SSL_FILETYPE_PEM)) {
        err = ERR_get_error();
        rb_lib_log("rb_setup_ssl_server: Error loading keyfile [%s]: %s", keyfile,
                   get_ssl_error(err));
        return 0;
    }

    if(dhfile != NULL) {
        /* DH parameters aren't necessary, but they are nice..if they didn't pass one..that is their problem */
        BIO *bio = BIO_new_file(dhfile, "r");
        if(bio != NULL) {
            dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
            if(dh == NULL) {
                err = ERR_get_error();
                rb_lib_log
                ("rb_setup_ssl_server: Error loading DH params file [%s]: %s",
                 dhfile, get_ssl_error(err));
                BIO_free(bio);
                return 0;
            }
            BIO_free(bio);
            SSL_CTX_set_tmp_dh(ssl_server_ctx, dh);
        } else {
            err = ERR_get_error();
            rb_lib_log("rb_setup_ssl_server: Error loading DH params file [%s]: %s",
                       dhfile, get_ssl_error(err));
        }
    }
    return 1;
}

int
rb_ssl_listen(rb_fde_t *F, int backlog, int defer_accept)
{
    int result;

    result = rb_listen(F, backlog, defer_accept);
    F->type = RB_FD_SOCKET | RB_FD_LISTEN | RB_FD_SSL;

    return result;
}

struct ssl_connect {
    CNCB *callback;
    void *data;
    int timeout;
};

static void
rb_ssl_connect_realcb(rb_fde_t *F, int status, struct ssl_connect *sconn)
{
    F->connect->callback = sconn->callback;
    F->connect->data = sconn->data;
    rb_free(sconn);
    rb_connect_callback(F, status);
}

static void
rb_ssl_tryconn_timeout_cb(rb_fde_t *F, void *data)
{
    rb_ssl_connect_realcb(F, RB_ERR_TIMEOUT, data);
}

static void
rb_ssl_tryconn_cb(rb_fde_t *F, void *data)
{
    struct ssl_connect *sconn = data;
    int ssl_err;
    if(!SSL_is_init_finished((SSL *) F->ssl)) {
        if((ssl_err = SSL_connect((SSL *) F->ssl)) <= 0) {
            switch (ssl_err = SSL_get_error((SSL *) F->ssl, ssl_err)) {
            case SSL_ERROR_SYSCALL:
                if(rb_ignore_errno(errno))
                case SSL_ERROR_WANT_READ:
            case SSL_ERROR_WANT_WRITE: {
                F->ssl_errno = get_last_err();
                rb_setselect(F, RB_SELECT_READ | RB_SELECT_WRITE,
                             rb_ssl_tryconn_cb, sconn);
                return;
            }
            default:
                F->ssl_errno = get_last_err();
                rb_ssl_connect_realcb(F, RB_ERROR_SSL, sconn);
                return;
            }
        } else {
            rb_ssl_connect_realcb(F, RB_OK, sconn);
        }
    }
}

static void
rb_ssl_tryconn(rb_fde_t *F, int status, void *data)
{
    struct ssl_connect *sconn = data;
    int ssl_err;
    if(status != RB_OK) {
        rb_ssl_connect_realcb(F, status, sconn);
        return;
    }

    F->type |= RB_FD_SSL;
    F->ssl = SSL_new(ssl_client_ctx);
    SSL_set_fd((SSL *) F->ssl, F->fd);
    rb_setup_ssl_cb(F);
    rb_settimeout(F, sconn->timeout, rb_ssl_tryconn_timeout_cb, sconn);
    if((ssl_err = SSL_connect((SSL *) F->ssl)) <= 0) {
        switch (ssl_err = SSL_get_error((SSL *) F->ssl, ssl_err)) {
        case SSL_ERROR_SYSCALL:
            if(rb_ignore_errno(errno))
            case SSL_ERROR_WANT_READ:
        case SSL_ERROR_WANT_WRITE: {
            F->ssl_errno = get_last_err();
            rb_setselect(F, RB_SELECT_READ | RB_SELECT_WRITE,
                         rb_ssl_tryconn_cb, sconn);
            return;
        }
        default:
            F->ssl_errno = get_last_err();
            rb_ssl_connect_realcb(F, RB_ERROR_SSL, sconn);
            return;
        }
    } else {
        rb_ssl_connect_realcb(F, RB_OK, sconn);
    }
}

void
rb_connect_tcp_ssl(rb_fde_t *F, struct sockaddr *dest,
                   struct sockaddr *clocal, int socklen, CNCB * callback, void *data, int timeout)
{
    struct ssl_connect *sconn;
    if(F == NULL)
        return;

    sconn = rb_malloc(sizeof(struct ssl_connect));
    sconn->data = data;
    sconn->callback = callback;
    sconn->timeout = timeout;
    rb_connect_tcp(F, dest, clocal, socklen, rb_ssl_tryconn, sconn, timeout);

}

void
rb_ssl_start_connected(rb_fde_t *F, CNCB * callback, void *data, int timeout)
{
    struct ssl_connect *sconn;
    int ssl_err;
    if(F == NULL)
        return;

    sconn = rb_malloc(sizeof(struct ssl_connect));
    sconn->data = data;
    sconn->callback = callback;
    sconn->timeout = timeout;
    F->connect = rb_malloc(sizeof(struct conndata));
    F->connect->callback = callback;
    F->connect->data = data;
    F->type |= RB_FD_SSL;
    F->ssl = SSL_new(ssl_client_ctx);

    SSL_set_fd((SSL *) F->ssl, F->fd);
    rb_setup_ssl_cb(F);
    rb_settimeout(F, sconn->timeout, rb_ssl_tryconn_timeout_cb, sconn);
    if((ssl_err = SSL_connect((SSL *) F->ssl)) <= 0) {
        switch (ssl_err = SSL_get_error((SSL *) F->ssl, ssl_err)) {
        case SSL_ERROR_SYSCALL:
            if(rb_ignore_errno(errno))
            case SSL_ERROR_WANT_READ:
        case SSL_ERROR_WANT_WRITE: {
            F->ssl_errno = get_last_err();
            rb_setselect(F, RB_SELECT_READ | RB_SELECT_WRITE,
                         rb_ssl_tryconn_cb, sconn);
            return;
        }
        default:
            F->ssl_errno = get_last_err();
            rb_ssl_connect_realcb(F, RB_ERROR_SSL, sconn);
            return;
        }
    } else {
        rb_ssl_connect_realcb(F, RB_OK, sconn);
    }
}

int
rb_init_prng(const char *path, prng_seed_t seed_type)
{
/* We may not have EGD (old OpenSSL / LibreSSL), fall back to default */
#ifndef HAVE_SSL_RAND_EGD
    if (seed_type == RB_PRNG_EGD) {
        seed_type = RB_PRNG_DEFAULT;
    }
#endif

    if(seed_type == RB_PRNG_DEFAULT) {
#ifdef _WIN32
        RAND_screen();
#endif
        return RAND_status();
    }
    if(path == NULL)
        return RAND_status();

    switch (seed_type) {
#ifdef HAVE_SSL_RAND_EGD
    case RB_PRNG_EGD:
        if(RAND_egd(path) == -1)
            return -1;
        break;
#endif
    case RB_PRNG_FILE:
        if(RAND_load_file(path, -1) == -1)
            return -1;
        break;
#ifdef _WIN32
    case RB_PRNGWIN32:
        RAND_screen();
        break;
#endif
    default:
        return -1;
    }

    return RAND_status();
}

int
rb_get_random(void *buf, size_t length)
{
    int ret;

    if((ret = RAND_bytes(buf, length)) == 0) {
        /* remove the error from the queue */
        ERR_get_error();
    }
    return ret;
}

int
rb_get_pseudo_random(void *buf, size_t length)
{
    int ret;
    ret = RAND_pseudo_bytes(buf, length);
    if(ret < 0)
        return 0;
    return 1;
}

const char *
rb_get_ssl_strerror(rb_fde_t *F)
{
    return get_ssl_error(F->ssl_errno);
}

int
rb_get_ssl_certfp(rb_fde_t *F, uint8_t certfp[RB_SSL_CERTFP_LEN])
{
    X509 *cert;
    int res;

    if (F->ssl == NULL)
        return 0;

    cert = SSL_get_peer_certificate((SSL *) F->ssl);
    if(cert != NULL) {
        res = SSL_get_verify_result((SSL *) F->ssl);
        if(res == X509_V_OK ||
           res == X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN ||
           res == X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE ||
           res == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT) {
            memcpy(certfp, cert->sha1_hash, RB_SSL_CERTFP_LEN);
            X509_free(cert);
            return 1;
        }
        X509_free(cert);
    }

    return 0;
}

int
rb_supports_ssl(void)
{
    return 1;
}

void
rb_get_ssl_info(char *buf, size_t len)
{
    rb_snprintf(buf, len, "Using SSL: %s compiled: 0x%lx, library 0x%lx",
                SSLeay_version(SSLEAY_VERSION),
                (long)OPENSSL_VERSION_NUMBER, SSLeay());
}


#endif /* HAVE_OPESSL */
