target: rtt: include rtt.h

[openocd.git] / src / server / server.c

// SPDX-License-Identifier: GPL-2.0-or-later

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007-2010 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "server.h"
#include <helper/time_support.h>
#include <target/target.h>
#include <target/target_request.h>
#include <target/openrisc/jsp_server.h>
#include "openocd.h"
#include "tcl_server.h"
#include "telnet_server.h"

#include <signal.h>

#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif

#ifndef _WIN32
#include <netinet/tcp.h>
#endif

static struct service *services;

enum shutdown_reason {
        CONTINUE_MAIN_LOOP,                     /* stay in main event loop */
        SHUTDOWN_REQUESTED,                     /* set by shutdown command; exit the event loop and quit the debugger */
        SHUTDOWN_WITH_ERROR_CODE,       /* set by shutdown command; quit with non-zero return code */
        SHUTDOWN_WITH_SIGNAL_CODE       /* set by sig_handler; exec shutdown then exit with signal as return code */
};
static enum shutdown_reason shutdown_openocd = CONTINUE_MAIN_LOOP;

/* store received signal to exit application by killing ourselves */
static int last_signal;

/* set the polling period to 100ms */
static int polling_period = 100;

/* address by name on which to listen for incoming TCP/IP connections */
static char *bindto_name;

static int add_connection(struct service *service, struct command_context *cmd_ctx)
{
        socklen_t address_size;
        struct connection *c, **p;
        int retval;
        int flag = 1;

        c = malloc(sizeof(struct connection));
        c->fd = -1;
        c->fd_out = -1;
        memset(&c->sin, 0, sizeof(c->sin));
        c->cmd_ctx = copy_command_context(cmd_ctx);
        c->service = service;
        c->input_pending = false;
        c->priv = NULL;
        c->next = NULL;

        if (service->type == CONNECTION_TCP) {
                address_size = sizeof(c->sin);

                c->fd = accept(service->fd, (struct sockaddr *)&service->sin, &address_size);
                c->fd_out = c->fd;

                /* This increases performance dramatically for e.g. GDB load which
                 * does not have a sliding window protocol.
                 *
                 * Ignore errors from this fn as it probably just means less performance
                 */
                setsockopt(c->fd,       /* socket affected */
                        IPPROTO_TCP,                    /* set option at TCP level */
                        TCP_NODELAY,                    /* name of option */
                        (char *)&flag,                  /* the cast is historical cruft */
                        sizeof(int));                   /* length of option value */

                LOG_INFO("accepting '%s' connection on tcp/%s", service->name, service->port);
                retval = service->new_connection(c);
                if (retval != ERROR_OK) {
                        close_socket(c->fd);
                        LOG_ERROR("attempted '%s' connection rejected", service->name);
                        command_done(c->cmd_ctx);
                        free(c);
                        return retval;
                }
        } else if (service->type == CONNECTION_STDINOUT) {
                c->fd = service->fd;
                c->fd_out = fileno(stdout);

#ifdef _WIN32
                /* we are using stdin/out so ignore ctrl-c under windoze */
                SetConsoleCtrlHandler(NULL, TRUE);
#endif

                /* do not check for new connections again on stdin */
                service->fd = -1;

                LOG_INFO("accepting '%s' connection from pipe", service->name);
                retval = service->new_connection(c);
                if (retval != ERROR_OK) {
                        LOG_ERROR("attempted '%s' connection rejected", service->name);
                        command_done(c->cmd_ctx);
                        free(c);
                        return retval;
                }
        } else if (service->type == CONNECTION_PIPE) {
                c->fd = service->fd;
                /* do not check for new connections again on stdin */
                service->fd = -1;

                char *out_file = alloc_printf("%so", service->port);
                c->fd_out = open(out_file, O_WRONLY);
                free(out_file);
                if (c->fd_out == -1) {
                        LOG_ERROR("could not open %s", service->port);
                        command_done(c->cmd_ctx);
                        free(c);
                        return ERROR_FAIL;
                }

                LOG_INFO("accepting '%s' connection from pipe %s", service->name, service->port);
                retval = service->new_connection(c);
                if (retval != ERROR_OK) {
                        LOG_ERROR("attempted '%s' connection rejected", service->name);
                        command_done(c->cmd_ctx);
                        free(c);
                        return retval;
                }
        }

        /* add to the end of linked list */
        for (p = &service->connections; *p; p = &(*p)->next)
                ;
        *p = c;

        if (service->max_connections != CONNECTION_LIMIT_UNLIMITED)
                service->max_connections--;

        return ERROR_OK;
}

static int remove_connection(struct service *service, struct connection *connection)
{
        struct connection **p = &service->connections;
        struct connection *c;

        /* find connection */
        while ((c = *p)) {
                if (c->fd == connection->fd) {
                        service->connection_closed(c);
                        if (service->type == CONNECTION_TCP)
                                close_socket(c->fd);
                        else if (service->type == CONNECTION_PIPE) {
                                /* The service will listen to the pipe again */
                                c->service->fd = c->fd;
                        }

                        command_done(c->cmd_ctx);

                        /* delete connection */
                        *p = c->next;
                        free(c);

                        if (service->max_connections != CONNECTION_LIMIT_UNLIMITED)
                                service->max_connections++;

                        break;
                }

                /* redirect p to next list pointer */
                p = &(*p)->next;
        }

        return ERROR_OK;
}

static void free_service(struct service *c)
{
        free(c->name);
        free(c->port);
        free(c);
}

int add_service(const struct service_driver *driver, const char *port,
                int max_connections, void *priv)
{
        struct service *c, **p;
        struct hostent *hp;
        int so_reuseaddr_option = 1;

        c = malloc(sizeof(struct service));

        c->name = strdup(driver->name);
        c->port = strdup(port);
        c->max_connections = 1; /* Only TCP/IP ports can support more than one connection */
        c->fd = -1;
        c->connections = NULL;
        c->new_connection_during_keep_alive = driver->new_connection_during_keep_alive_handler;
        c->new_connection = driver->new_connection_handler;
        c->input = driver->input_handler;
        c->connection_closed = driver->connection_closed_handler;
        c->keep_client_alive = driver->keep_client_alive_handler;
        c->priv = priv;
        c->next = NULL;
        long portnumber;
        if (strcmp(c->port, "pipe") == 0)
                c->type = CONNECTION_STDINOUT;
        else {
                char *end;
                portnumber = strtol(c->port, &end, 0);
                if (!*end && (parse_long(c->port, &portnumber) == ERROR_OK)) {
                        c->portnumber = portnumber;
                        c->type = CONNECTION_TCP;
                } else
                        c->type = CONNECTION_PIPE;
        }

        if (c->type == CONNECTION_TCP) {
                c->max_connections = max_connections;

                c->fd = socket(AF_INET, SOCK_STREAM, 0);
                if (c->fd == -1) {
                        LOG_ERROR("error creating socket: %s", strerror(errno));
                        free_service(c);
                        return ERROR_FAIL;
                }

                setsockopt(c->fd,
                        SOL_SOCKET,
                        SO_REUSEADDR,
                        (void *)&so_reuseaddr_option,
                        sizeof(int));

                socket_nonblock(c->fd);

                memset(&c->sin, 0, sizeof(c->sin));
                c->sin.sin_family = AF_INET;

                if (!bindto_name)
                        c->sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
                else {
                        hp = gethostbyname(bindto_name);
                        if (!hp) {
                                LOG_ERROR("couldn't resolve bindto address: %s", bindto_name);
                                close_socket(c->fd);
                                free_service(c);
                                return ERROR_FAIL;
                        }
                        memcpy(&c->sin.sin_addr, hp->h_addr_list[0], hp->h_length);
                }
                c->sin.sin_port = htons(c->portnumber);

                if (bind(c->fd, (struct sockaddr *)&c->sin, sizeof(c->sin)) == -1) {
                        LOG_ERROR("couldn't bind %s to socket on port %d: %s", c->name, c->portnumber, strerror(errno));
                        close_socket(c->fd);
                        free_service(c);
                        return ERROR_FAIL;
                }

#ifndef _WIN32
                int segsize = 65536;
                setsockopt(c->fd, IPPROTO_TCP, TCP_MAXSEG,  &segsize, sizeof(int));
#endif
                int window_size = 128 * 1024;

                /* These setsockopt()s must happen before the listen() */

                setsockopt(c->fd, SOL_SOCKET, SO_SNDBUF,
                        (char *)&window_size, sizeof(window_size));
                setsockopt(c->fd, SOL_SOCKET, SO_RCVBUF,
                        (char *)&window_size, sizeof(window_size));

                if (listen(c->fd, 1) == -1) {
                        LOG_ERROR("couldn't listen on socket: %s", strerror(errno));
                        close_socket(c->fd);
                        free_service(c);
                        return ERROR_FAIL;
                }

                struct sockaddr_in addr_in;
                addr_in.sin_port = 0;
                socklen_t addr_in_size = sizeof(addr_in);
                if (getsockname(c->fd, (struct sockaddr *)&addr_in, &addr_in_size) == 0)
                        LOG_INFO("Listening on port %hu for %s connections",
                                 ntohs(addr_in.sin_port), c->name);
        } else if (c->type == CONNECTION_STDINOUT) {
                c->fd = fileno(stdin);

#ifdef _WIN32
                /* for win32 set stdin/stdout to binary mode */
                if (_setmode(_fileno(stdout), _O_BINARY) < 0)
                        LOG_WARNING("cannot change stdout mode to binary");
                if (_setmode(_fileno(stdin), _O_BINARY) < 0)
                        LOG_WARNING("cannot change stdin mode to binary");
                if (_setmode(_fileno(stderr), _O_BINARY) < 0)
                        LOG_WARNING("cannot change stderr mode to binary");
#else
                socket_nonblock(c->fd);
#endif
        } else if (c->type == CONNECTION_PIPE) {
#ifdef _WIN32
                /* we currently do not support named pipes under win32
                 * so exit openocd for now */
                LOG_ERROR("Named pipes currently not supported under this os");
                free_service(c);
                return ERROR_FAIL;
#else
                /* Pipe we're reading from */
                c->fd = open(c->port, O_RDONLY | O_NONBLOCK);
                if (c->fd == -1) {
                        LOG_ERROR("could not open %s", c->port);
                        free_service(c);
                        return ERROR_FAIL;
                }
#endif
        }

        /* add to the end of linked list */
        for (p = &services; *p; p = &(*p)->next)
                ;
        *p = c;

        return ERROR_OK;
}

static void remove_connections(struct service *service)
{
        struct connection *connection;

        connection = service->connections;

        while (connection) {
                struct connection *tmp;

                tmp = connection->next;
                remove_connection(service, connection);
                connection = tmp;
        }
}

int remove_service(const char *name, const char *port)
{
        struct service *tmp;
        struct service *prev;

        prev = services;

        for (tmp = services; tmp; prev = tmp, tmp = tmp->next) {
                if (!strcmp(tmp->name, name) && !strcmp(tmp->port, port)) {
                        remove_connections(tmp);

                        if (tmp == services)
                                services = tmp->next;
                        else
                                prev->next = tmp->next;

                        if (tmp->type != CONNECTION_STDINOUT)
                                close_socket(tmp->fd);

                        free(tmp->priv);
                        free_service(tmp);

                        return ERROR_OK;
                }
        }

        return ERROR_OK;
}

static int remove_services(void)
{
        struct service *c = services;

        /* loop service */
        while (c) {
                struct service *next = c->next;

                remove_connections(c);

                free(c->name);

                if (c->type == CONNECTION_PIPE) {
                        if (c->fd != -1)
                                close(c->fd);
                }
                free(c->port);
                free(c->priv);
                /* delete service */
                free(c);

                /* remember the last service for unlinking */
                c = next;
        }

        services = NULL;

        return ERROR_OK;
}

void server_keep_clients_alive(void)
{
        for (struct service *s = services; s; s = s->next)
                if (s->keep_client_alive)
                        for (struct connection *c = s->connections; c; c = c->next)
                                s->keep_client_alive(c);
}

int server_loop(struct command_context *command_context)
{
        struct service *service;

        bool poll_ok = true;

        /* used in select() */
        fd_set read_fds;
        int fd_max;

        /* used in accept() */
        int retval;

        int64_t next_event = timeval_ms() + polling_period;

#ifndef _WIN32
        if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
                LOG_ERROR("couldn't set SIGPIPE to SIG_IGN");
#endif

        while (shutdown_openocd == CONTINUE_MAIN_LOOP) {
                /* monitor sockets for activity */
                fd_max = 0;
                FD_ZERO(&read_fds);

                /* add service and connection fds to read_fds */
                for (service = services; service; service = service->next) {
                        if (service->fd != -1) {
                                /* listen for new connections */
                                FD_SET(service->fd, &read_fds);

                                if (service->fd > fd_max)
                                        fd_max = service->fd;
                        }

                        if (service->connections) {
                                struct connection *c;

                                for (c = service->connections; c; c = c->next) {
                                        /* check for activity on the connection */
                                        FD_SET(c->fd, &read_fds);
                                        if (c->fd > fd_max)
                                                fd_max = c->fd;
                                }
                        }
                }

                struct timeval tv;
                tv.tv_sec = 0;
                if (poll_ok) {
                        /* we're just polling this iteration, this is faster on embedded
                         * hosts */
                        tv.tv_usec = 0;
                        retval = socket_select(fd_max + 1, &read_fds, NULL, NULL, &tv);
                } else {
                        /* Timeout socket_select() when a target timer expires or every polling_period */
                        int timeout_ms = next_event - timeval_ms();
                        if (timeout_ms < 0)
                                timeout_ms = 0;
                        else if (timeout_ms > polling_period)
                                timeout_ms = polling_period;
                        tv.tv_usec = timeout_ms * 1000;
                        /* Only while we're sleeping we'll let others run */
                        retval = socket_select(fd_max + 1, &read_fds, NULL, NULL, &tv);
                }

                if (retval == -1) {
#ifdef _WIN32

                        errno = WSAGetLastError();

                        if (errno == WSAEINTR)
                                FD_ZERO(&read_fds);
                        else {
                                LOG_ERROR("error during select: %s", strerror(errno));
                                return ERROR_FAIL;
                        }
#else

                        if (errno == EINTR)
                                FD_ZERO(&read_fds);
                        else {
                                LOG_ERROR("error during select: %s", strerror(errno));
                                return ERROR_FAIL;
                        }
#endif
                }

                if (retval == 0) {
                        /* Execute callbacks of expired timers when
                         * - there was nothing to do if poll_ok was true
                         * - socket_select() timed out if poll_ok was false, now one or more
                         *   timers expired or the polling period elapsed
                         */
                        target_call_timer_callbacks();
                        next_event = target_timer_next_event();
                        process_jim_events(command_context);

                        FD_ZERO(&read_fds);     /* eCos leaves read_fds unchanged in this case!  */

                        /* We timed out/there was nothing to do, timeout rather than poll next time
                         **/
                        poll_ok = false;
                } else {
                        /* There was something to do, next time we'll just poll */
                        poll_ok = true;
                }

                /* This is a simple back-off algorithm where we immediately
                 * re-poll if we did something this time around.
                 *
                 * This greatly improves performance of DCC.
                 */
                poll_ok = poll_ok || target_got_message();

                for (service = services; service; service = service->next) {
                        /* handle new connections on listeners */
                        if ((service->fd != -1)
                                && (FD_ISSET(service->fd, &read_fds))) {
                                if (service->max_connections != 0)
                                        add_connection(service, command_context);
                                else {
                                        if (service->type == CONNECTION_TCP) {
                                                struct sockaddr_in sin;
                                                socklen_t address_size = sizeof(sin);
                                                int tmp_fd;
                                                tmp_fd = accept(service->fd,
                                                                (struct sockaddr *)&service->sin,
                                                                &address_size);
                                                close_socket(tmp_fd);
                                        }
                                        LOG_INFO(
                                                "rejected '%s' connection, no more connections allowed",
                                                service->name);
                                }
                        }

                        /* handle activity on connections */
                        if (service->connections) {
                                struct connection *c;

                                for (c = service->connections; c; ) {
                                        if ((c->fd >= 0 && FD_ISSET(c->fd, &read_fds)) || c->input_pending) {
                                                retval = service->input(c);
                                                if (retval != ERROR_OK) {
                                                        struct connection *next = c->next;
                                                        if (service->type == CONNECTION_PIPE ||
                                                                        service->type == CONNECTION_STDINOUT) {
                                                                /* if connection uses a pipe then
                                                                 * shutdown openocd on error */
                                                                shutdown_openocd = SHUTDOWN_REQUESTED;
                                                        }
                                                        remove_connection(service, c);
                                                        LOG_INFO("dropped '%s' connection",
                                                                service->name);
                                                        c = next;
                                                        continue;
                                                }
                                        }
                                        c = c->next;
                                }
                        }
                }

#ifdef _WIN32
                MSG msg;
                while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
                        if (msg.message == WM_QUIT)
                                shutdown_openocd = SHUTDOWN_WITH_SIGNAL_CODE;
                }
#endif
        }

        /* when quit for signal or CTRL-C, run (eventually user implemented) "shutdown" */
        if (shutdown_openocd == SHUTDOWN_WITH_SIGNAL_CODE)
                command_run_line(command_context, "shutdown");

        return shutdown_openocd == SHUTDOWN_WITH_ERROR_CODE ? ERROR_FAIL : ERROR_OK;
}

static void sig_handler(int sig)
{
        /* store only first signal that hits us */
        if (shutdown_openocd == CONTINUE_MAIN_LOOP) {
                shutdown_openocd = SHUTDOWN_WITH_SIGNAL_CODE;
                last_signal = sig;
                LOG_DEBUG("Terminating on Signal %d", sig);
        } else
                LOG_DEBUG("Ignored extra Signal %d", sig);
}


#ifdef _WIN32
BOOL WINAPI control_handler(DWORD ctrl_type)
{
        shutdown_openocd = SHUTDOWN_WITH_SIGNAL_CODE;
        return TRUE;
}
#else
static void sigkey_handler(int sig)
{
        /* ignore keystroke generated signals if not in foreground process group */

        if (tcgetpgrp(STDIN_FILENO) > 0)
                sig_handler(sig);
        else
                LOG_DEBUG("Ignored Signal %d", sig);
}
#endif


int server_host_os_entry(void)
{
        /* this currently only calls WSAStartup on native win32 systems
         * before any socket operations are performed.
         * This is an issue if you call init in your config script */

#ifdef _WIN32
        WORD version_requested;
        WSADATA wsadata;

        version_requested = MAKEWORD(2, 2);

        if (WSAStartup(version_requested, &wsadata) != 0) {
                LOG_ERROR("Failed to Open Winsock");
                return ERROR_FAIL;
        }
#endif
        return ERROR_OK;
}

int server_host_os_close(void)
{
#ifdef _WIN32
        WSACleanup();
#endif
        return ERROR_OK;
}

int server_preinit(void)
{
#ifdef _WIN32
        /* register ctrl-c handler */
        SetConsoleCtrlHandler(control_handler, TRUE);

        signal(SIGBREAK, sig_handler);
        signal(SIGINT, sig_handler);
#else
        signal(SIGHUP, sig_handler);
        signal(SIGPIPE, sig_handler);
        signal(SIGQUIT, sigkey_handler);
        signal(SIGINT, sigkey_handler);
#endif
        signal(SIGTERM, sig_handler);
        signal(SIGABRT, sig_handler);

        return ERROR_OK;
}

int server_init(struct command_context *cmd_ctx)
{
        int ret = tcl_init();

        if (ret != ERROR_OK)
                return ret;

        ret = telnet_init("Open On-Chip Debugger");

        if (ret != ERROR_OK) {
                remove_services();
                return ret;
        }

        return ERROR_OK;
}

int server_quit(void)
{
        remove_services();
        target_quit();

#ifdef _WIN32
        SetConsoleCtrlHandler(control_handler, FALSE);

        return ERROR_OK;
#endif

        /* return signal number so we can kill ourselves */
        return last_signal;
}

void server_free(void)
{
        tcl_service_free();
        telnet_service_free();
        jsp_service_free();

        free(bindto_name);
}

void exit_on_signal(int sig)
{
#ifndef _WIN32
        /* bring back default system handler and kill yourself */
        signal(sig, SIG_DFL);
        kill(getpid(), sig);
#endif
}

int connection_write(struct connection *connection, const void *data, int len)
{
        if (len == 0) {
                /* successful no-op. Sockets and pipes behave differently here... */
                return 0;
        }
        if (connection->service->type == CONNECTION_TCP)
                return write_socket(connection->fd_out, data, len);
        else
                return write(connection->fd_out, data, len);
}

int connection_read(struct connection *connection, void *data, int len)
{
        if (connection->service->type == CONNECTION_TCP)
                return read_socket(connection->fd, data, len);
        else
                return read(connection->fd, data, len);
}

bool openocd_is_shutdown_pending(void)
{
        return shutdown_openocd != CONTINUE_MAIN_LOOP;
}

/* tell the server we want to shut down */
COMMAND_HANDLER(handle_shutdown_command)
{
        LOG_USER("shutdown command invoked");

        shutdown_openocd = SHUTDOWN_REQUESTED;

        command_run_line(CMD_CTX, "_run_pre_shutdown_commands");

        if (CMD_ARGC == 1) {
                if (!strcmp(CMD_ARGV[0], "error")) {
                        shutdown_openocd = SHUTDOWN_WITH_ERROR_CODE;
                        return ERROR_FAIL;
                }
        }

        return ERROR_COMMAND_CLOSE_CONNECTION;
}

COMMAND_HANDLER(handle_poll_period_command)
{
        if (CMD_ARGC == 0)
                LOG_WARNING("You need to set a period value");
        else
                COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], polling_period);

        LOG_INFO("set servers polling period to %ums", polling_period);

        return ERROR_OK;
}

COMMAND_HANDLER(handle_bindto_command)
{
        switch (CMD_ARGC) {
                case 0:
                        command_print(CMD, "bindto name: %s", bindto_name);
                        break;
                case 1:
                        free(bindto_name);
                        bindto_name = strdup(CMD_ARGV[0]);
                        break;
                default:
                        return ERROR_COMMAND_SYNTAX_ERROR;
        }
        return ERROR_OK;
}

static const struct command_registration server_command_handlers[] = {
        {
                .name = "shutdown",
                .handler = &handle_shutdown_command,
                .mode = COMMAND_ANY,
                .usage = "",
                .help = "shut the server down",
        },
        {
                .name = "poll_period",
                .handler = &handle_poll_period_command,
                .mode = COMMAND_ANY,
                .usage = "",
                .help = "set the servers polling period",
        },
        {
                .name = "bindto",
                .handler = &handle_bindto_command,
                .mode = COMMAND_CONFIG,
                .usage = "[name]",
                .help = "Specify address by name on which to listen for "
                        "incoming TCP/IP connections",
        },
        COMMAND_REGISTRATION_DONE
};

int server_register_commands(struct command_context *cmd_ctx)
{
        int retval = telnet_register_commands(cmd_ctx);
        if (retval != ERROR_OK)
                return retval;

        retval = tcl_register_commands(cmd_ctx);
        if (retval != ERROR_OK)
                return retval;

        retval = jsp_register_commands(cmd_ctx);
        if (retval != ERROR_OK)
                return retval;

        return register_commands(cmd_ctx, NULL, server_command_handlers);
}

COMMAND_HELPER(server_port_command, unsigned short *out)
{
        switch (CMD_ARGC) {
                case 0:
                        command_print(CMD, "%d", *out);
                        break;
                case 1:
                {
                        uint16_t port;
                        COMMAND_PARSE_NUMBER(u16, CMD_ARGV[0], port);
                        *out = port;
                        break;
                }
                default:
                        return ERROR_COMMAND_SYNTAX_ERROR;
        }
        return ERROR_OK;
}

COMMAND_HELPER(server_pipe_command, char **out)
{
        switch (CMD_ARGC) {
                case 0:
                        command_print(CMD, "%s", *out);
                        break;
                case 1:
                {
                        if (CMD_CTX->mode == COMMAND_EXEC) {
                                LOG_WARNING("unable to change server port after init");
                                return ERROR_COMMAND_ARGUMENT_INVALID;
                        }
                        free(*out);
                        *out = strdup(CMD_ARGV[0]);
                        break;
                }
                default:
                        return ERROR_COMMAND_SYNTAX_ERROR;
        }
        return ERROR_OK;
}