/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


typedef struct {
    ngx_str_t  engine;
} ngx_openssl_conf_t;


static ngx_int_t ngx_ssl_handle_recv(ngx_connection_t *c, int n);
static void ngx_ssl_write_handler(ngx_event_t *wev);
static void ngx_ssl_read_handler(ngx_event_t *rev);
static void *ngx_openssl_create_conf(ngx_cycle_t *cycle);
static char *ngx_openssl_init_conf(ngx_cycle_t *cycle, void *conf);

#if !(NGX_SSL_ENGINE)
static char *ngx_openssl_noengine(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
#endif


static ngx_command_t  ngx_openssl_commands[] = {

    { ngx_string("ssl_engine"),
      NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
#if (NGX_SSL_ENGINE)
      ngx_conf_set_str_slot,
#else
      ngx_openssl_noengine,
#endif
      0,
      offsetof(ngx_openssl_conf_t, engine),
      NULL },

      ngx_null_command
};


static ngx_core_module_t  ngx_openssl_module_ctx = {
    ngx_string("openssl"),
    ngx_openssl_create_conf,
    ngx_openssl_init_conf
};  


ngx_module_t  ngx_openssl_module = {
    NGX_MODULE_V1,
    &ngx_openssl_module_ctx,               /* module context */
    ngx_openssl_commands,                  /* module directives */
    NGX_CORE_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};  


ngx_int_t
ngx_ssl_init(ngx_log_t *log)
{
    SSL_library_init();
    SSL_load_error_strings();

#if (NGX_SSL_ENGINE)
    ENGINE_load_builtin_engines();
#endif

    return NGX_OK;
}


ngx_int_t
ngx_ssl_create_session(ngx_ssl_ctx_t *ssl_ctx, ngx_connection_t *c,
    ngx_uint_t flags)
{   
    ngx_ssl_t  *ssl;

    ssl = ngx_pcalloc(c->pool, sizeof(ngx_ssl_t));
    if (ssl == NULL) {
        return NGX_ERROR;
    }

    ssl->buf = ngx_create_temp_buf(c->pool, NGX_SSL_BUFSIZE);
    if (ssl->buf == NULL) {
        return NGX_ERROR;
    }

    if (flags & NGX_SSL_BUFFER) {
        ssl->buffer = 1;
    }

    ssl->ssl = SSL_new(ssl_ctx);

    if (ssl->ssl == NULL) {
        ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "SSL_new() failed");
        return NGX_ERROR;
    }

    if (SSL_set_fd(ssl->ssl, c->fd) == 0) {
        ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "SSL_set_fd() failed");
        return NGX_ERROR;
    }

    SSL_set_accept_state(ssl->ssl);

    c->ssl = ssl;

    return NGX_OK;
}


ssize_t
ngx_ssl_recv(ngx_connection_t *c, u_char *buf, size_t size)
{
    int  n, bytes;

    if (c->ssl->last == NGX_ERROR) {
        return NGX_ERROR;
    }

    bytes = 0;

    /*
     * SSL_read() may return data in parts, so try to read
     * until SSL_read() would return no data
     */

    for ( ;; ) {

        n = SSL_read(c->ssl->ssl, buf, size);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_read: %d", n); 

        if (n > 0) {

            bytes += n;

#if (NGX_DEBUG)

            if (!c->ssl->handshaked && SSL_is_init_finished(c->ssl->ssl)) {
                char         buf[129], *s, *d;
                SSL_CIPHER  *cipher;

                c->ssl->handshaked = 1;

                cipher = SSL_get_current_cipher(c->ssl->ssl);

                if (cipher) {
                    SSL_CIPHER_description(cipher, &buf[1], 128);

                    for (s = &buf[1], d = buf; *s; s++) {
                        if (*s == ' ' && *d == ' ') {
                            continue;
                        }

                        if (*s == LF || *s == CR) {
                            continue;
                        }

                        *++d = *s;
                    }

                    if (*d != ' ') {
                        d++;
                    }

                    *d = '\0';

                    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                                   "SSL cipher: \"%s\"", &buf[1]); 
                } else {
                    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
                                   "SSL no shared ciphers"); 
                }
            }
#endif

        }

        c->ssl->last = ngx_ssl_handle_recv(c, n);

        if (c->ssl->last != NGX_OK) {

            if (bytes) {
                return bytes;

            } else {
                return c->ssl->last;
            }
        }

        size -= n;

        if (size == 0) {
            return bytes;
        }

        buf += n;
    }
}


static ngx_int_t
ngx_ssl_handle_recv(ngx_connection_t *c, int n)
{
    int         sslerr;
    ngx_err_t   err;
    char       *handshake;

    if (n > 0) {

        if (c->ssl->saved_write_handler) {

            c->write->handler = c->ssl->saved_write_handler;
            c->ssl->saved_write_handler = NULL;
            c->write->ready = 1;

            if (ngx_handle_write_event(c->write, 0) == NGX_ERROR) {
                return NGX_ERROR;
            }

            if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
                return NGX_ERROR;
            }

            ngx_post_event(c->write);

            ngx_mutex_unlock(ngx_posted_events_mutex);
        }

        return NGX_OK;
    }

    if (!SSL_is_init_finished(c->ssl->ssl)) {
        handshake = " in SSL handshake";

    } else {
        handshake = "";
    }

    sslerr = SSL_get_error(c->ssl->ssl, n);

    err = (sslerr == SSL_ERROR_SYSCALL) ? ngx_errno : 0;

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_get_error: %d", sslerr);

    if (sslerr == SSL_ERROR_WANT_READ) {
        c->read->ready = 0;
        return NGX_AGAIN;
    }

    if (sslerr == SSL_ERROR_WANT_WRITE) {

        ngx_log_error(NGX_LOG_INFO, c->log, err,
                      "client does SSL %shandshake",
                      SSL_is_init_finished(c->ssl->ssl) ? "re" : "");

        c->write->ready = 0;

        if (ngx_handle_write_event(c->write, 0) == NGX_ERROR) {
            return NGX_ERROR;
        }

        /*
         * we do not set the timer because there is already the read event timer
         */

        if (c->ssl->saved_write_handler == NULL) {
            c->ssl->saved_write_handler = c->write->handler;
            c->write->handler = ngx_ssl_write_handler;
        }

        return NGX_AGAIN;
    }

    c->ssl->no_rcv_shut = 1;
    c->ssl->no_send_shut = 1;

    if (sslerr == SSL_ERROR_ZERO_RETURN || ERR_peek_error() == 0) {
        ngx_log_error(NGX_LOG_INFO, c->log, err,
                      "client closed connection%s", handshake);

        return NGX_ERROR;
    }

    ngx_ssl_error(NGX_LOG_ALERT, c->log, err,
                  "SSL_read() failed%s", handshake);

    return NGX_ERROR;
}


static void
ngx_ssl_write_handler(ngx_event_t *wev)
{
    ngx_connection_t  *c;

    c = wev->data;
    c->read->handler(c->read);
}


/*
 * OpenSSL has no SSL_writev() so we copy several bufs into our 16K buffer
 * before the SSL_write() call to decrease a SSL overhead.
 *
 * Besides for protocols such as HTTP it is possible to always buffer
 * the output to decrease a SSL overhead some more.
 */

ngx_chain_t *
ngx_ssl_send_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
{
    int          n;
    ngx_uint_t   flush;
    ssize_t      send, size;
    ngx_buf_t   *buf;

    buf = c->ssl->buf;

    if (in && in->next == NULL && !c->buffered && !c->ssl->buffer) {

        /*
         * we avoid a buffer copy if the incoming buf is a single,
         * our buffer is empty, and we do not need to buffer the output
         */

        n = ngx_ssl_write(c, in->buf->pos, in->buf->last - in->buf->pos);

        if (n == NGX_ERROR) {
            return NGX_CHAIN_ERROR;
        }

        if (n == NGX_AGAIN) {
            c->buffered = 1;
            return in;
        }

        in->buf->pos += n;

        return in;
    }


    /* the maximum limit size is the maximum uint32_t value - the page size */

    if (limit == 0 || limit > NGX_MAX_UINT32_VALUE - ngx_pagesize) {
        limit = NGX_MAX_UINT32_VALUE - ngx_pagesize;
    }


    send = 0;
    flush = (in == NULL) ? 1 : 0;

    for ( ;; ) {

        while (in && buf->last < buf->end) {
            if (in->buf->last_buf) {
                flush = 1;
            }

            if (ngx_buf_special(in->buf)) {
                in = in->next;
                continue;
            }

            size = in->buf->last - in->buf->pos;

            if (size > buf->end - buf->last) {
                size = buf->end - buf->last;
            }

            /*
             * TODO: the taking in->buf->flush into account can be
             *       implemented using the limit on the higher level
             */

            if (send + size > limit) {
                size = limit - send;
                flush = 1;
            }

            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                           "SSL buf copy: %d", size);

            ngx_memcpy(buf->last, in->buf->pos, size);

            buf->last += size;

            in->buf->pos += size;
            if (in->buf->pos == in->buf->last) {
                in = in->next;
            }
        }

        size = buf->last - buf->pos;

        if (!flush && buf->last < buf->end && c->ssl->buffer) {
            break;
        }

        n = ngx_ssl_write(c, buf->pos, size);

        if (n == NGX_ERROR) {
            return NGX_CHAIN_ERROR;
        }

        if (n == NGX_AGAIN) {
            c->buffered = 1;
            return in;
        }

        buf->pos += n;
        send += n;
        c->sent += n;

        if (n < size) {
            break;
        }

        if (buf->pos == buf->last) {
            buf->pos = buf->start;
            buf->last = buf->start;
        }

        if (in == NULL || send == limit) {
            break;
        }
    }

    c->buffered = (buf->pos < buf->last) ? 1 : 0;

    return in;
}


ssize_t
ngx_ssl_write(ngx_connection_t *c, u_char *data, size_t size)
{
    int        n, sslerr;
    ngx_err_t  err;

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL to write: %d", size);

    n = SSL_write(c->ssl->ssl, data, size);

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_write: %d", n);

    if (n > 0) {

#if (NGX_DEBUG)

        if (!c->ssl->handshaked && SSL_is_init_finished(c->ssl->ssl)) {
            char         buf[129], *s, *d;
            SSL_CIPHER  *cipher;

            c->ssl->handshaked = 1;

            cipher = SSL_get_current_cipher(c->ssl->ssl);

            if (cipher) {
                SSL_CIPHER_description(cipher, &buf[1], 128);

                for (s = &buf[1], d = buf; *s; s++) {
                    if (*s == ' ' && *d == ' ') {
                        continue;
                    }

                    if (*s == LF || *s == CR) {
                        continue;
                    }

                    *++d = *s;
                }

                if (*d != ' ') {
                    d++;
                }

                *d = '\0';

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                               "SSL cipher: \"%s\"", &buf[1]); 
            } else {
                ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
                               "SSL no shared ciphers"); 
            }
        }
#endif

        if (c->ssl->saved_read_handler) {

            c->read->handler = c->ssl->saved_read_handler;
            c->ssl->saved_read_handler = NULL;
            c->read->ready = 1;

            if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
                return NGX_ERROR;
            }

            if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
                return NGX_ERROR;
            }

            ngx_post_event(c->read);

            ngx_mutex_unlock(ngx_posted_events_mutex);
        }

        return n;
    }

    sslerr = SSL_get_error(c->ssl->ssl, n);

    err = (sslerr == SSL_ERROR_SYSCALL) ? ngx_errno : 0;

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_get_error: %d", sslerr);

    if (sslerr == SSL_ERROR_WANT_WRITE) {
        c->write->ready = 0;
        return NGX_AGAIN;
    }

    if (sslerr == SSL_ERROR_WANT_READ) {

        ngx_log_error(NGX_LOG_INFO, c->log, err,
                      "client does SSL %shandshake",
                      SSL_is_init_finished(c->ssl->ssl) ? "re" : "");

        c->read->ready = 0;

        if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
            return NGX_ERROR;
        }

        /*
         * we do not set the timer because there is already
         * the write event timer
         */

        if (c->ssl->saved_read_handler == NULL) {
            c->ssl->saved_read_handler = c->read->handler;
            c->read->handler = ngx_ssl_read_handler;
        }

        return NGX_AGAIN;
    }

    c->ssl->no_rcv_shut = 1;
    c->ssl->no_send_shut = 1;

    ngx_ssl_error(NGX_LOG_ALERT, c->log, err, "SSL_write() failed");

    return NGX_ERROR;
}


static void
ngx_ssl_read_handler(ngx_event_t *rev)
{
    ngx_connection_t  *c;

    c = rev->data;
    c->write->handler(c->write);
}


ngx_int_t
ngx_ssl_shutdown(ngx_connection_t *c)
{
    int         n, sslerr, mode;
    ngx_uint_t  again;

    if (!c->ssl->shutdown_set) {

        /* it seems that SSL_set_shutdown() could be called once only */

        if (c->read->timedout) {
            mode = SSL_RECEIVED_SHUTDOWN|SSL_SENT_SHUTDOWN;

        } else {
            mode = 0;

            if (c->ssl->no_rcv_shut) {
                mode = SSL_RECEIVED_SHUTDOWN;
            }

            if (c->ssl->no_send_shut) {
                mode |= SSL_SENT_SHUTDOWN;
            }
        }

        if (mode) {
            SSL_set_shutdown(c->ssl->ssl, mode);
            c->ssl->shutdown_set = 1;
        }
    }

    again = 0;
#if (NGX_SUPPRESS_WARN)
    sslerr = 0;
#endif

    for ( ;; ) {
        n = SSL_shutdown(c->ssl->ssl);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "SSL_shutdown: %d", n);

        if (n == 1 || (n == 0 && c->read->timedout)) {
            SSL_free(c->ssl->ssl);
            c->ssl = NULL;
            return NGX_OK;
        }

        if (n == 0) {
            again = 1;
            break;
        }

        break;
    }

    if (!again) {
        sslerr = SSL_get_error(c->ssl->ssl, n);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "SSL_get_error: %d", sslerr);
    }

    if (again || sslerr == SSL_ERROR_WANT_READ) {

        ngx_add_timer(c->read, 30000);

        if (ngx_handle_read_event(c->read, 0) == NGX_ERROR) {
            return NGX_ERROR;
        }

        return NGX_AGAIN;
    }

    if (sslerr == SSL_ERROR_WANT_WRITE) {

        if (ngx_handle_write_event(c->write, 0) == NGX_ERROR) {
            return NGX_ERROR;
        }

        return NGX_AGAIN;
    }

    ngx_ssl_error(NGX_LOG_ALERT, c->log, 0, "SSL_shutdown() failed");

    return NGX_ERROR;
}


void
ngx_ssl_error(ngx_uint_t level, ngx_log_t *log, ngx_err_t err, char *fmt, ...)
{   
    u_char   errstr[NGX_MAX_CONF_ERRSTR], *p, *last;
    va_list  args;

    last = errstr + NGX_MAX_CONF_ERRSTR;

    va_start(args, fmt);
    p = ngx_vsnprintf(errstr, sizeof(errstr) - 1, fmt, args);
    va_end(args);

    p = ngx_cpystrn(p, (u_char *) " (SSL: ", last - p);

    ERR_error_string_n(ERR_get_error(), (char *) p, last - p);

    ngx_log_error(level, log, err, "%s)", errstr);
}


void
ngx_ssl_cleanup_ctx(void *data)
{
   SSL_CTX  *ctx = data;

   SSL_CTX_free(ctx);
}


static void *
ngx_openssl_create_conf(ngx_cycle_t *cycle)
{
    ngx_openssl_conf_t  *oscf;
    
    oscf = ngx_pcalloc(cycle->pool, sizeof(ngx_openssl_conf_t));
    if (oscf == NULL) {
        return NGX_CONF_ERROR;
    }
    
    /*
     * set by ngx_pcalloc():
     * 
     *     oscf->engine.len = 0;
     *     oscf->engine.data = NULL;
     */    

    return oscf;
}


static char *
ngx_openssl_init_conf(ngx_cycle_t *cycle, void *conf)
{
#if (NGX_SSL_ENGINE)
    ngx_openssl_conf_t *oscf = conf;
    
    ENGINE  *engine;

    if (oscf->engine.len == 0) {
        return NGX_CONF_OK;
    }
    
    engine = ENGINE_by_id((const char *) oscf->engine.data);

    if (engine == NULL) {
        ngx_ssl_error(NGX_LOG_WARN, cycle->log, 0,
                      "ENGINE_by_id(\"%V\") failed", &oscf->engine);
        return NGX_CONF_ERROR;
    }

    if (ENGINE_set_default(engine, ENGINE_METHOD_ALL) == 0) {
        ngx_ssl_error(NGX_LOG_WARN, cycle->log, 0,
                      "ENGINE_set_default(\"%V\", ENGINE_METHOD_ALL) failed",
                      &oscf->engine);
        return NGX_CONF_ERROR;
    }

    ENGINE_free(engine);

#endif

    return NGX_CONF_OK;
}


#if !(NGX_SSL_ENGINE)

static char *
ngx_openssl_noengine(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "\"ssl_engine\" is not supported: " NGX_SSL_NAME
                       " library does not support crypto accelerators");

    return NGX_CONF_ERROR;
}

#endif