core.c

        return NULL;
    }

    apr_sockaddr_ip_get(&c->local_ip, c->local_addr);
    if ((rv = apr_socket_addr_get(&c->client_addr, APR_REMOTE, csd))
        != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_INFO, rv, server, APLOGNO(00138)
                     "apr_socket_addr_get(APR_REMOTE)");
        apr_socket_close(csd);
        return NULL;
    }

    apr_sockaddr_ip_get(&c->client_ip, c->client_addr);
    c->base_server = server;

    c->id = id;
    c->bucket_alloc = alloc;

    c->clogging_input_filters = 0;

    return c;
}

static int core_pre_connection(conn_rec *c, void *csd)
{
    core_net_rec *net = apr_palloc(c->pool, sizeof(*net));
    apr_status_t rv;

    /* The Nagle algorithm says that we should delay sending partial
     * packets in hopes of getting more data.  We don't want to do
     * this; we are not telnet.  There are bad interactions between
     * persistent connections and Nagle's algorithm that have very severe
     * performance penalties.  (Failing to disable Nagle is not much of a
     * problem with simple HTTP.)
     */
    rv = apr_socket_opt_set(csd, APR_TCP_NODELAY, 1);
    if (rv != APR_SUCCESS && rv != APR_ENOTIMPL) {
        /* expected cause is that the client disconnected already,
         * hence the debug level
         */
        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, rv, c, APLOGNO(00139)
                      "apr_socket_opt_set(APR_TCP_NODELAY)");
    }

    /* The core filter requires the timeout mode to be set, which
     * incidentally sets the socket to be nonblocking.  If this
     * is not initialized correctly, Linux - for example - will
     * be initially blocking, while Solaris will be non blocking
     * and any initial read will fail.
     */
    rv = apr_socket_timeout_set(csd, c->base_server->timeout);
    if (rv != APR_SUCCESS) {
        /* expected cause is that the client disconnected already */
        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, rv, c, APLOGNO(00140)
                      "apr_socket_timeout_set");
    }

    net->c = c;
    net->in_ctx = NULL;
    net->out_ctx = NULL;
    net->client_socket = csd;

    ap_set_core_module_config(net->c->conn_config, csd);
    ap_add_input_filter_handle(ap_core_input_filter_handle, net, NULL, net->c);
    ap_add_output_filter_handle(ap_core_output_filter_handle, net, NULL, net->c);
    return DONE;
}

AP_DECLARE(int) ap_state_query(int query)
{
    switch (query) {
    case AP_SQ_MAIN_STATE:
        return ap_main_state;
    case AP_SQ_RUN_MODE:
        return ap_run_mode;
    case AP_SQ_CONFIG_GEN:
        return ap_config_generation;
    default:
        return AP_SQ_NOT_SUPPORTED;
    }
}

static apr_random_t *rng = NULL;
#if APR_HAS_THREADS
static apr_thread_mutex_t *rng_mutex = NULL;
#endif

static void core_child_init(apr_pool_t *pchild, server_rec *s)
{
    apr_proc_t proc;
#if APR_HAS_THREADS
    int threaded_mpm;
    if (ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded_mpm) == APR_SUCCESS
        && threaded_mpm)
    {
        apr_thread_mutex_create(&rng_mutex, APR_THREAD_MUTEX_DEFAULT, pchild);
    }
#endif
    /* The MPMs use plain fork() and not apr_proc_fork(), so we have to call
     * apr_random_after_fork() manually in the child
     */
    proc.pid = getpid();
    apr_random_after_fork(&proc);
}

static void core_optional_fn_retrieve(void)
{
    ap_init_scoreboard(NULL);
}

AP_CORE_DECLARE(void) ap_random_parent_after_fork(void)
{
    /*
     * To ensure that the RNG state in the parent changes after the fork, we
     * pull some data from the RNG and discard it. This ensures that the RNG
     * states in the children are different even after the pid wraps around.
     * As we only use apr_random for insecure random bytes, pulling 2 bytes
     * should be enough.
     * XXX: APR should probably have some dedicated API to do this, but it
     * XXX: currently doesn't.
     */
    apr_uint16_t data;
    apr_random_insecure_bytes(rng, &data, sizeof(data));
}

AP_CORE_DECLARE(void) ap_init_rng(apr_pool_t *p)
{
    unsigned char seed[8];
    apr_status_t rv;
    rng = apr_random_standard_new(p);
    do {
        rv = apr_generate_random_bytes(seed, sizeof(seed));
        if (rv != APR_SUCCESS)
            goto error;
        apr_random_add_entropy(rng, seed, sizeof(seed));
        rv = apr_random_insecure_ready(rng);
    } while (rv == APR_ENOTENOUGHENTROPY);
    if (rv == APR_SUCCESS)
        return;
error:
    ap_log_error(APLOG_MARK, APLOG_CRIT, rv, NULL, APLOGNO(00141)
                 "Could not initialize random number generator");
    exit(1);
}

AP_DECLARE(void) ap_random_insecure_bytes(void *buf, apr_size_t size)
{
#if APR_HAS_THREADS
    if (rng_mutex)
        apr_thread_mutex_lock(rng_mutex);
#endif
    /* apr_random_insecure_bytes can only fail with APR_ENOTENOUGHENTROPY,
     * and we have ruled that out during initialization. Therefore we don't
     * need to check the return code.
     */
    apr_random_insecure_bytes(rng, buf, size);
#if APR_HAS_THREADS
    if (rng_mutex)
        apr_thread_mutex_unlock(rng_mutex);
#endif
}

/*
 * Finding a random number in a range.
 *      n' = a + n(b-a+1)/(M+1)
 * where:
 *      n' = random number in range
 *      a  = low end of range
 *      b  = high end of range
 *      n  = random number of 0..M
 *      M  = maxint
 * Algorithm 'borrowed' from PHP's rand() function.
 */
#define RAND_RANGE(__n, __min, __max, __tmax) \
(__n) = (__min) + (long) ((double) ((__max) - (__min) + 1.0) * ((__n) / ((__tmax) + 1.0)))
AP_DECLARE(apr_uint32_t) ap_random_pick(apr_uint32_t min, apr_uint32_t max)
{
    apr_uint32_t number;
#if (!__GNUC__ || __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8) || \
     !__sparc__ || APR_SIZEOF_VOIDP != 8)
    /* This triggers a gcc bug on sparc/64bit with gcc < 4.8, PR 52900 */
    if (max < 16384) {
        apr_uint16_t num16;
        ap_random_insecure_bytes(&num16, sizeof(num16));
        RAND_RANGE(num16, min, max, APR_UINT16_MAX);
        number = num16;
    }
    else
#endif
    {
        ap_random_insecure_bytes(&number, sizeof(number));
        RAND_RANGE(number, min, max, APR_UINT32_MAX);
    }
    return number;
}

static apr_status_t core_insert_network_bucket(conn_rec *c,
                                               apr_bucket_brigade *bb,
                                               apr_socket_t *socket)
{
    apr_bucket *e = apr_bucket_socket_create(socket, c->bucket_alloc);
    APR_BRIGADE_INSERT_TAIL(bb, e);
    return APR_SUCCESS;
}

static apr_status_t core_dirwalk_stat(apr_finfo_t *finfo, request_rec *r,
                                      apr_int32_t wanted) 
{
    return apr_stat(finfo, r->filename, wanted, r->pool);
}

static void core_dump_config(apr_pool_t *p, server_rec *s)
{
    core_server_config *sconf = ap_get_core_module_config(s->module_config);
    apr_file_t *out = NULL;
    const char *tmp;
    const char **defines;
    int i;
    if (!ap_exists_config_define("DUMP_RUN_CFG"))
        return;

    apr_file_open_stdout(&out, p);
    apr_file_printf(out, "ServerRoot: \"%s\"\n", ap_server_root);
    tmp = ap_server_root_relative(p, sconf->ap_document_root);
    apr_file_printf(out, "Main DocumentRoot: \"%s\"\n", tmp);
    if (s->error_fname[0] != '|' && strcmp(s->error_fname, "syslog") != 0)
        tmp = ap_server_root_relative(p, s->error_fname);
    else
        tmp = s->error_fname;
    apr_file_printf(out, "Main ErrorLog: \"%s\"\n", tmp);
    if (ap_scoreboard_fname) {
        tmp = ap_server_root_relative(p, ap_scoreboard_fname);
        apr_file_printf(out, "ScoreBoardFile: \"%s\"\n", tmp);
    }
    ap_dump_mutexes(p, s, out);
    ap_mpm_dump_pidfile(p, out);

    defines = (const char **)ap_server_config_defines->elts;
    for (i = 0; i < ap_server_config_defines->nelts; i++) {
        const char *name = defines[i];
        const char *val = NULL;
        if (server_config_defined_vars)
           val = apr_table_get(server_config_defined_vars, name);
        if (val)
            apr_file_printf(out, "Define: %s=%s\n", name, val);
        else
            apr_file_printf(out, "Define: %s\n", name);
    }
}

static int core_upgrade_handler(request_rec *r)
{
    conn_rec *c = r->connection;
    const char *upgrade;

    if (c->master) {
        /* Not possible to perform an HTTP/1.1 upgrade from a slave
         * connection. */
        return DECLINED;
    }
    
    upgrade = apr_table_get(r->headers_in, "Upgrade");
    if (upgrade && *upgrade) {
        const char *conn = apr_table_get(r->headers_in, "Connection");
        if (ap_find_token(r->pool, conn, "upgrade")) {
            apr_array_header_t *offers = NULL;
            const char *err;
            
            err = ap_parse_token_list_strict(r->pool, upgrade, &offers, 0);
            if (err) {
                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02910)
                              "parsing Upgrade header: %s", err);
                return DECLINED;
            }
            
            if (offers && offers->nelts > 0) {
                const char *protocol = ap_select_protocol(c, r, NULL, offers);
                if (protocol && strcmp(protocol, ap_get_protocol(c))) {
                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02909)
                                  "Upgrade selects '%s'", protocol);
                    /* Let the client know what we are upgrading to. */
                    apr_table_clear(r->headers_out);
                    apr_table_setn(r->headers_out, "Upgrade", protocol);
                    apr_table_setn(r->headers_out, "Connection", "Upgrade");
                    
                    r->status = HTTP_SWITCHING_PROTOCOLS;
                    r->status_line = ap_get_status_line(r->status);
                    ap_send_interim_response(r, 1);

                    ap_switch_protocol(c, r, r->server, protocol);

                    /* make sure httpd closes the connection after this */
                    c->keepalive = AP_CONN_CLOSE;
                    return DONE;
                }
            }
        }
    }
    else if (!c->keepalives) {
        /* first request on a master connection, if we have protocols other
         * than the current one enabled here, announce them to the
         * client. If the client is already talking a protocol with requests
         * on slave connections, leave it be. */
        const apr_array_header_t *upgrades;
        ap_get_protocol_upgrades(c, r, NULL, 0, &upgrades);
        if (upgrades && upgrades->nelts > 0) {
            char *protocols = apr_array_pstrcat(r->pool, upgrades, ',');
            apr_table_setn(r->headers_out, "Upgrade", protocols);
            apr_table_setn(r->headers_out, "Connection", "Upgrade");
        }
    }
    
    return DECLINED;
}

static int core_upgrade_storage(request_rec *r)
{
    if ((r->method_number == M_OPTIONS) && r->uri && (r->uri[0] == '*') &&
        (r->uri[1] == '\0')) {
        return core_upgrade_handler(r);
    }
    return DECLINED;
}

static void register_hooks(apr_pool_t *p)
{
    errorlog_hash = apr_hash_make(p);
    ap_register_log_hooks(p);
    ap_register_config_hooks(p);
    ap_expr_init(p);

    /* create_connection and pre_connection should always be hooked
     * APR_HOOK_REALLY_LAST by core to give other modules the opportunity
     * to install alternate network transports and stop other functions
     * from being run.
     */
    ap_hook_create_connection(core_create_conn, NULL, NULL,
                              APR_HOOK_REALLY_LAST);
    ap_hook_pre_connection(core_pre_connection, NULL, NULL,
                           APR_HOOK_REALLY_LAST);

    ap_hook_pre_config(core_pre_config, NULL, NULL, APR_HOOK_REALLY_FIRST);
    ap_hook_post_config(core_post_config,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_check_config(core_check_config,NULL,NULL,APR_HOOK_FIRST);
    ap_hook_test_config(core_dump_config,NULL,NULL,APR_HOOK_FIRST);
    ap_hook_translate_name(ap_core_translate,NULL,NULL,APR_HOOK_REALLY_LAST);
    ap_hook_map_to_storage(core_upgrade_storage,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_map_to_storage(core_map_to_storage,NULL,NULL,APR_HOOK_REALLY_LAST);
    ap_hook_open_logs(ap_open_logs,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_child_init(core_child_init,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_child_init(ap_logs_child_init,NULL,NULL,APR_HOOK_MIDDLE);
    ap_hook_handler(core_upgrade_handler,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_handler(default_handler,NULL,NULL,APR_HOOK_REALLY_LAST);
    /* FIXME: I suspect we can eliminate the need for these do_nothings - Ben */
    ap_hook_type_checker(do_nothing,NULL,NULL,APR_HOOK_REALLY_LAST);
    ap_hook_fixups(core_override_type,NULL,NULL,APR_HOOK_REALLY_FIRST);
    ap_hook_create_request(core_create_req, NULL, NULL, APR_HOOK_MIDDLE);
    APR_OPTIONAL_HOOK(proxy, create_req, core_create_proxy_req, NULL, NULL,
                      APR_HOOK_MIDDLE);
    ap_hook_pre_mpm(ap_create_scoreboard, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_child_status(ap_core_child_status, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_insert_network_bucket(core_insert_network_bucket, NULL, NULL,
                                  APR_HOOK_REALLY_LAST);
    ap_hook_dirwalk_stat(core_dirwalk_stat, NULL, NULL, APR_HOOK_REALLY_LAST);
    ap_hook_open_htaccess(ap_open_htaccess, NULL, NULL, APR_HOOK_REALLY_LAST);
    ap_hook_optional_fn_retrieve(core_optional_fn_retrieve, NULL, NULL,
                                 APR_HOOK_MIDDLE);
    
    /* register the core's insert_filter hook and register core-provided
     * filters
     */
    ap_hook_insert_filter(core_insert_filter, NULL, NULL, APR_HOOK_MIDDLE);

    ap_core_input_filter_handle =
        ap_register_input_filter("CORE_IN", ap_core_input_filter,
                                 NULL, AP_FTYPE_NETWORK);
    ap_content_length_filter_handle =
        ap_register_output_filter("CONTENT_LENGTH", ap_content_length_filter,
                                  NULL, AP_FTYPE_PROTOCOL);
    ap_core_output_filter_handle =
        ap_register_output_filter("CORE", ap_core_output_filter,
                                  NULL, AP_FTYPE_NETWORK);
    ap_subreq_core_filter_handle =
        ap_register_output_filter("SUBREQ_CORE", ap_sub_req_output_filter,
                                  NULL, AP_FTYPE_CONTENT_SET);
    ap_old_write_func =
        ap_register_output_filter("OLD_WRITE", ap_old_write_filter,
                                  NULL, AP_FTYPE_RESOURCE - 10);
}

AP_DECLARE_MODULE(core) = {
    MPM20_MODULE_STUFF,
    AP_PLATFORM_REWRITE_ARGS_HOOK, /* hook to run before apache parses args */
    create_core_dir_config,       /* create per-directory config structure */
    merge_core_dir_configs,       /* merge per-directory config structures */
    create_core_server_config,    /* create per-server config structure */
    merge_core_server_configs,    /* merge per-server config structures */
    core_cmds,                    /* command apr_table_t */
    register_hooks                /* register hooks */
};