[paraslash.git] / command.c

/*
 * Copyright (C) 1997-2007 Andre Noll <maan@systemlinux.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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 */

/** \file command.c does client authentication and executes server commands */

#include <sys/time.h> /* gettimeofday */
#include "server.cmdline.h"
#include "db.h"
#include "server.h"
#include "vss.h"
#include "send.h"
#include "rc4.h"
#include <openssl/rc4.h>
#include "error.h"
#include "net.h"
#include "daemon.h"
#include "string.h"
#include "fd.h"
#include "user_list.h"
#include "server_command_list.h"

static RC4_KEY rc4_recv_key;
static RC4_KEY rc4_send_key;
static unsigned char rc4_buf[2 * RC4_KEY_LEN];

extern const char *status_item_list[NUM_STAT_ITEMS];
extern struct misc_meta_data *mmd;
extern struct audio_file_selector selectors[];
extern struct sender senders[];
extern char *user_list;
struct sockaddr_in *in_addr;

static void dummy(__a_unused int s)
{}

static void mmd_dup(struct misc_meta_data *new_mmd)
{
        mmd_lock();
        *new_mmd = *mmd;
        mmd_unlock();
}

/*
 * compute human readable string containing
 * vss status for given integer value
 */
static char *vss_status_tohuman(unsigned int flags)
{
        if (flags & VSS_PLAYING)
                return para_strdup("playing");
        else if (flags & VSS_NEXT)
                return para_strdup("stopped");
        else
                return para_strdup("paused");
}

/*
 * return human readable permission string. Never returns NULL.
 */
static char *cmd_perms_itohuman(unsigned int perms)
{
        char *msg = para_malloc(5 * sizeof(char));

        msg[0] = perms & DB_READ? 'a' : '-';
        msg[1] = perms & DB_WRITE? 'A' : '-';
        msg[2] = perms & VSS_READ? 'v' : '-';
        msg[3] = perms & VSS_WRITE? 'V' : '-';
        msg[4] = '\0';
        return msg;
}

/*
 * Never returns NULL.
 */
static char *vss_get_status_flags(unsigned int flags)
{
        char *msg = para_malloc(5 * sizeof(char));

        msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
        msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
        msg[2] = (flags & VSS_NEXT)? 'N' : '_';
        msg[3] = (flags & VSS_REPOS)? 'R' : '_';
        msg[4] = '\0';
        return msg;
}

/*
 * compute status bar string. Never returns NULL
 */
static char *get_sb_string(struct misc_meta_data *nmmd)
{
        char *base, *ret;
        long long unsigned secs = 0, rsecs = 0, percent = 0;

        base = para_basename(nmmd->filename);
        if (!base)
                return para_strdup("");
        if (!base[0])
                return base;
        if (nmmd->chunks_total) {
                secs = (long long) nmmd->seconds_total * nmmd->chunks_sent
                        / nmmd->chunks_total;
                rsecs = (long long) nmmd->seconds_total *
                        (nmmd->chunks_total - nmmd->chunks_sent)
                        / nmmd->chunks_total;
                percent = 100 * ((nmmd->chunks_sent + 5) / 10)
                        / ((nmmd->chunks_total + 5) / 10);
        }
        ret = make_message("%llu:%02llu [%llu:%02llu] (%llu%%) %s",
                secs / 60, secs % 60,
                rsecs / 60, rsecs % 60,
                percent,
                base
        );
        free(base);
        return ret;
}

static char *get_status(struct misc_meta_data *nmmd)
{
        char *bar, *ret, mtime[30] = "";
        char *status, *flags; /* vss status info */
        char *ut = uptime_str();
        long offset = (nmmd->offset + 500) / 1000;
        struct timeval now;
        struct tm mtime_tm;

        if (nmmd->audio_format >= 0) {
                localtime_r(&nmmd->mtime, &mtime_tm);
                strftime(mtime, 29, "%a %b %d %Y", &mtime_tm);
        }
        /* report real status */
        status = vss_status_tohuman(nmmd->vss_status_flags);
        flags = vss_get_status_flags(nmmd->vss_status_flags);
        bar = para_basename(nmmd->filename);
        gettimeofday(&now, NULL);
        ret = make_message(
                "%s:%lu\n"      "%s:%s\n"               "%s:%i\n"       "%s:%u\n"
                "%s:%s\n"       "%s:%s\n"       "%s:%s\n"       "%s:%s\n"
                "%s:%li\n"      "%s:%s\n"       "%s"            "%s"
                "%s:%s\n"       "%s:%lu.%lu\n"  "%s:%lu.%lu\n",
                status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
                status_item_list[SI_MTIME], mtime,
                status_item_list[SI_LENGTH], nmmd->seconds_total,
                status_item_list[SI_NUM_PLAYED], nmmd->num_played,

                status_item_list[SI_STATUS_BAR], bar ? bar : "(none)",
                status_item_list[SI_STATUS], status,
                status_item_list[SI_STATUS_FLAGS], flags,
                status_item_list[SI_SELECTOR], selectors[nmmd->selector_num].name,

                status_item_list[SI_OFFSET], offset,
                status_item_list[SI_FORMAT], audio_format_name(nmmd->audio_format),
                nmmd->selector_info,
                nmmd->audio_file_info,

                status_item_list[SI_UPTIME], ut,
                status_item_list[SI_STREAM_START],
                        (long unsigned)nmmd->stream_start.tv_sec,
                        (long unsigned)nmmd->stream_start.tv_usec,
                status_item_list[SI_CURRENT_TIME],
                        (long unsigned)now.tv_sec,
                        (long unsigned)now.tv_usec

        );
        free(bar);
        free(flags);
        free(status);
        free(ut);
        return ret;
}

static int check_sender_args(int argc, char **argv, struct sender_command_data *scd)
{
        int i;
        /* this has to match sender.h */
        const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};

        scd->sender_num = -1;
        if (argc < 2)
                return -E_COMMAND_SYNTAX;
        for (i = 0; senders[i].name; i++)
                if (!strcmp(senders[i].name, argv[1]))
                        break;
        PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
        if (!senders[i].name)
                return -E_COMMAND_SYNTAX;
        scd->sender_num = i;
        for (i = 0; subcmds[i]; i++)
                if (!strcmp(subcmds[i], argv[2]))
                        break;
        if (!subcmds[i])
                return -E_COMMAND_SYNTAX;
        scd->cmd_num = i;
        mmd_lock();
        if (!senders[scd->sender_num].client_cmds[scd->cmd_num]) {
                mmd_unlock();
                return -E_SENDER_CMD;
        }
        mmd_unlock();
        switch (scd->cmd_num) {
        case SENDER_ON:
        case SENDER_OFF:
                if (argc != 3)
                        return -E_COMMAND_SYNTAX;
                break;
        case SENDER_DENY:
        case SENDER_ALLOW:
                if (argc != 4 && argc != 5)
                        return -E_COMMAND_SYNTAX;
                if (!inet_aton(argv[3], &scd->addr))
                        return -E_COMMAND_SYNTAX;
                scd->netmask = 32;
                if (argc == 5) {
                        scd->netmask = atoi(argv[4]);
                        if (scd->netmask < 0 || scd->netmask > 32)
                                return -E_COMMAND_SYNTAX;
                }
                break;
        case SENDER_ADD:
        case SENDER_DELETE:
                if (argc != 4 && argc != 5)
                        return -E_COMMAND_SYNTAX;
                if (!inet_aton(argv[3], &scd->addr))
                        return -E_COMMAND_SYNTAX;
                scd->port = -1;
                if (argc == 5) {
                        scd->port = atoi(argv[4]);
                        if (scd->port < 0 || scd->port > 65535)
                                return -E_COMMAND_SYNTAX;
                }
                break;
        default:
                return -E_COMMAND_SYNTAX;
        }
        return 1;
}

int com_sender(int fd, int argc, char **argv)
{
        int i, ret;
        struct sender_command_data scd;

        if (argc < 2) {
                char *msg = NULL;
                for (i = 0; senders[i].name; i++) {
                        char *tmp = make_message("%s%s\n",
                                msg? msg : "", senders[i].name);
                        free(msg);
                        msg = tmp;
                }
                ret = send_buffer(fd, msg);
                free(msg);
                return ret;
        }
        ret = check_sender_args(argc, argv, &scd);
        if (ret < 0) {
                char *msg;
                if (scd.sender_num < 0)
                        return ret;
                msg = senders[scd.sender_num].help();
                send_buffer(fd, msg);
                free(msg);
                return 1;
        }
        for (i = 0; i < 10; i++) {
                mmd_lock();
                if (mmd->sender_cmd_data.cmd_num >= 0) {
                        mmd_unlock();
                        usleep(100 * 1000);
                        continue;
                }
                mmd->sender_cmd_data = scd;
                mmd_unlock();
                break;
        }
        return (i < 10)? 1 : -E_LOCK;
}

/* server info */
int com_si(int fd, int argc, __a_unused char **argv)
{
        int i, ret;
        char *ut;
        char *selector_string = NULL, *sender_info = NULL, *sender_list = NULL;

        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        for (i = 0; selectors[i].name; i++) {
                selector_string = para_strcat(selector_string, selectors[i].name);
                selector_string = para_strcat(selector_string, " ");
        }
        for (i = 0; senders[i].name; i++) {
                char *info = senders[i].info();
                sender_info = para_strcat(sender_info, info);
                free(info);
                sender_list = para_strcat(sender_list, senders[i].name);
                sender_list = para_strcat(sender_list, " ");
        }
        ut = uptime_str();
        ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
                "pid: %d\n"
                "connections (active/accepted/total): %u/%u/%u\n"
                "current loglevel: %i\n"
                "supported audio file selectors: %s\n"
                "supported audio formats: %s\n"
                "supported senders: %s\n"
                "%s",
                ut, mmd->num_played,
                getppid(),
                mmd->active_connections,
                mmd->num_commands,
                mmd->num_connects,
                conf.loglevel_arg,
                selector_string,
                supported_audio_formats(),
                sender_list,
                sender_info
        );
        mmd_unlock();
        free(ut);
        free(selector_string);
        free(sender_list);
        free(sender_info);
        return ret;
}

/* version */
int com_version(int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        return send_buffer(socket_fd, "para_server-" PACKAGE_VERSION ", \""
                        CODENAME "\"\n"
                        COPYRIGHT "\n"
                        "built: " BUILD_DATE "\n"
                        SYSTEM ", " CC_VERSION "\n"
                );
}

/* sc */
int com_sc(int socket_fd, int argc, char **argv)
{
        char *name = NULL;
        int ret, old = 0, count = -1; /* print af change forever */

        if (argc > 1)
                count = atoi(argv[1]);
repeat:
        mmd_lock();
        if (old != mmd->num_played) {
                old = mmd->num_played;
                name = para_strdup(mmd->filename);
        }
        mmd_unlock();
        if (name) {
                ret = send_va_buffer(socket_fd, "%s\n", name);
                free(name);
                name = NULL;
                if (ret < 0)
                        return ret;
                if (argc > 1 && !--count)
                        return 1;
        }
        usleep(500000);
        goto repeat;
}

/* sb */
int com_sb(int socket_fd, int argc, char **argv)
{
        char *sb;
        int ret, nr = -1;       /* status bar will be printed that many
                                 * times. Negative value means: print
                                 * forever
                                 */
        if (argc > 1)
                nr = atoi(argv[1]);
        while (nr) {
                mmd_lock();
                sb = get_sb_string(mmd);
                mmd_unlock();
                ret = send_va_buffer(socket_fd, "%s\n", sb);
                free(sb);
                if (ret < 0)
                        return ret;
                if (nr == 1)
                        return 1;
                usleep(500000);
                if (nr > 0)
                        nr--;
        }
        return 1;
}

/* stat */
int com_stat(int socket_fd, int argc, char **argv)
{
        int ret, num = 0;/* status will be printed that many
                          * times. num <= 0 means: print forever
                          */
        struct misc_meta_data tmp, *nmmd = &tmp;
        char *s;

        signal(SIGUSR1, dummy);

        if (argc > 1)
                num = atoi(argv[1]);
        for (;;) {

                mmd_dup(nmmd);
                s = get_status(nmmd);
                ret = send_buffer(socket_fd, s);
                free(s);
                if (ret < 0)
                        goto out;
                ret = 1;
                if (num == 1)
                        goto out;
                sleep(50);
                if (getppid() == 1)
                        return -E_SERVER_CRASH;
        }
out:
        return ret;
}

static int send_list_of_commands(int fd, struct server_command *cmd,
                const char *handler)
{
        int ret, i;

        for (i = 1; cmd->name; cmd++, i++) {
                char *perms = cmd_perms_itohuman(cmd->perms);
                ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
                        handler,
                        perms,
                        cmd->description);
                free(perms);
                if (ret < 0)
                        return ret;
        }
        return 1;
}

/* always returns string that must be freed by the caller in handler */
static struct server_command *get_cmd_ptr(char *name, char **handler)
{
        struct server_command *cmd;

        for (cmd = server_cmds; cmd->name; cmd++)
                if (!strcmp(cmd->name, name)) {
                        if (handler)
                                *handler = para_strdup("para_server"); /* server commands */
                        return cmd;
                }
        /* not found, look for commands supported by the current selector */
        mmd_lock();
        if (handler)
                *handler = make_message("the %s selector",
                        selectors[mmd->selector_num].name);
        cmd = selectors[mmd->selector_num].cmd_list;
        mmd_unlock();
        for (; cmd->name; cmd++)
                if (!strcmp(cmd->name, name))
                        return cmd;
        return NULL;
}

/* help */
int com_help(int fd, int argc, char **argv)
{
        struct server_command *cmd;
        char *perms, *handler;
        int ret;

        if (argc < 2) {
                /* no argument given, print list of commands */
                if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
                        return ret;
                mmd_lock();
                handler = para_strdup(selectors[mmd->selector_num].name);
                cmd = selectors[mmd->selector_num].cmd_list;
                mmd_unlock();
                ret = send_list_of_commands(fd, cmd, handler);
                free(handler);
                return ret;
        }
        /* argument given for help */
        cmd = get_cmd_ptr(argv[1], &handler);
        if (!cmd) {
                free(handler);
                return -E_BAD_CMD;
        }
        perms = cmd_perms_itohuman(cmd->perms);
        ret = send_va_buffer(fd,
                "%s - %s\n\n"
                "handler: %s\n"
                "permissions: %s\n"
                "usage: %s\n\n"
                "%s\n",
                argv[1],
                cmd->description,
                handler,
                perms,
                cmd->usage,
                cmd->help
        );
        free(perms);
        free(handler);
        return ret;
}

/* hup */
int com_hup(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        kill(getppid(), SIGHUP);
        return 1;
}

/* term */
int com_term(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        kill(getppid(), SIGTERM);
        return 1;
}

int com_play(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        mmd->new_vss_status_flags |= VSS_PLAYING;
        mmd->new_vss_status_flags &= ~VSS_NOMORE;
        mmd_unlock();
        return 1;

}

/* stop */
int com_stop(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        mmd->new_vss_status_flags &= ~VSS_PLAYING;
        mmd->new_vss_status_flags &= ~VSS_REPOS;
        mmd->new_vss_status_flags |= VSS_NEXT;
        mmd_unlock();
        return 1;
}

/* pause */
int com_pause(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        if (!vss_paused())
                mmd->events++;
        mmd->new_vss_status_flags &= ~VSS_PLAYING;
        mmd->new_vss_status_flags &= ~VSS_NEXT;
        mmd_unlock();
        return 1;
}

int com_chs(int fd, int argc, char **argv)
{
        int i, ret;

        if (argc == 1) {
                char *selector;
                mmd_lock();
                selector = para_strdup(selectors[mmd->selector_num].name);
                mmd_unlock();
                ret = send_va_buffer(fd, "%s\n", selector);
                free(selector);
                return ret;
        }
        for (i = 0; selectors[i].name; i++) {
                if (strcmp(selectors[i].name, argv[1]))
                        continue;
                mmd_lock();
                mmd->selector_change = i;
                mmd->events++;
                mmd_unlock();
                return 1;
        }
        return -E_BAD_SELECTOR;
}

/* next */
int com_next(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        mmd->events++;
        mmd->new_vss_status_flags |= VSS_NEXT;
        mmd_unlock();
        return 1;
}

/* nomore */
int com_nomore(__a_unused int socket_fd, int argc, __a_unused char **argv)
{
        if (argc != 1)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        if (vss_playing() || vss_paused())
                mmd->new_vss_status_flags |= VSS_NOMORE;
        mmd_unlock();
        return 1;
}

/* ff */
int com_ff(__a_unused int socket_fd, int argc, char **argv)
{
        long promille;
        int ret, backwards = 0;
        unsigned i;
        char c;

        if (argc != 2)
                return -E_COMMAND_SYNTAX;
        if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
                return -E_COMMAND_SYNTAX;
        if (ret > 1 && c == '-')
                backwards = 1; /* jmp backwards */
        mmd_lock();
        ret = -E_NO_AUDIO_FILE;
        if (!mmd->chunks_total || !mmd->seconds_total)
                goto out;
        promille = (1000 * mmd->current_chunk) / mmd->chunks_total;
        if (backwards)
                promille -= 1000 * i / mmd->seconds_total;
        else
                promille += 1000 * i / mmd->seconds_total;
        if (promille < 0)
                promille = 0;
        if (promille >  1000) {
                mmd->new_vss_status_flags |= VSS_NEXT;
                goto out;
        }
        mmd->repos_request = (mmd->chunks_total * promille) / 1000;
        mmd->new_vss_status_flags |= VSS_REPOS;
        mmd->new_vss_status_flags &= ~VSS_NEXT;
        mmd->events++;
        ret = 1;
out:
        mmd_unlock();
        return ret;
}

/* jmp */
int com_jmp(__a_unused int socket_fd, int argc, char **argv)
{
        long unsigned int i;
        int ret;

        if (argc != 2)
                return -E_COMMAND_SYNTAX;
        if (sscanf(argv[1], "%lu", &i) <= 0)
                return -E_COMMAND_SYNTAX;
        mmd_lock();
        ret = -E_NO_AUDIO_FILE;
        if (!mmd->chunks_total)
                goto out;
        if (i > 100)
                i = 100;
        PARA_INFO_LOG("jumping to %lu%%\n", i);
        mmd->repos_request = (mmd->chunks_total * i + 50)/ 100;
        PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
                mmd->chunks_sent, mmd->offset);
        mmd->new_vss_status_flags |= VSS_REPOS;
        mmd->new_vss_status_flags &= ~VSS_NEXT;
        ret = 1;
        mmd->events++;
out:
        mmd_unlock();
        return ret;
}

/*
 * check if perms are sufficient to exec a command having perms cmd_perms.
 * Returns 0 if perms are sufficient, -E_PERM otherwise.
 */
static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
{
        PARA_DEBUG_LOG("%s", "checking permissions\n");
        return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
}

/*
 * Parse first string from *cmd and lookup in table of valid commands.
 * On error, NULL is returned.
 */
static struct server_command *parse_cmd(const char *cmdstr)
{
        char buf[255];
        int n = 0;

        sscanf(cmdstr, "%200s%n", buf, &n);
        if (!n)
                return NULL;
        buf[n] = '\0';
        return get_cmd_ptr(buf, NULL);
}

long int para_rand(long unsigned max)
{
        return (long int) ((max + 0.0) * (random() / (RAND_MAX + 1.0)));
}

static void init_rc4_keys(void)
{
        int i;

        for (i = 0; i < 2 * RC4_KEY_LEN; i++)
                rc4_buf[i] = para_rand(256);
        PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
                (unsigned char) rc4_buf[0],
                (unsigned char) rc4_buf[RC4_KEY_LEN]);
        RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
        RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
}

static void rc4_recv(unsigned long len, const unsigned char *indata,
                unsigned char *outdata, __a_unused void *private_data)
{
        RC4(&rc4_recv_key, len, indata, outdata);
}

static void rc4_send(unsigned long len, const unsigned char *indata,
                unsigned char *outdata, __a_unused void *private_data)
{
        RC4(&rc4_send_key, len, indata, outdata);
}

int handle_connect(int fd, struct sockaddr_in *addr)
{
        int numbytes, ret, argc, use_rc4 = 0;
        char buf[STRINGSIZE];
        unsigned char crypt_buf[MAXLINE];
        struct user u;
        struct server_command *cmd = NULL;
        long unsigned challenge_nr, chall_response;
        char **argv = NULL;
        char *p, *command = NULL;

        signal(SIGCHLD, SIG_IGN);
        signal(SIGINT, SIG_DFL);
        signal(SIGTERM, SIG_DFL);
        signal(SIGHUP, SIG_DFL);
        signal(SIGUSR1, SIG_IGN);

        in_addr = addr;
        challenge_nr = random();
        /* send Welcome message */
        ret = send_va_buffer(fd, "This is para_server, version "
                PACKAGE_VERSION  ".\n" );
        if (ret < 0)
                goto err_out;
        /* recv auth request line */
        ret = recv_buffer(fd, buf, sizeof(buf));
        if (ret < 0)
                goto err_out;
        if (ret <= 6) {
                ret = -E_AUTH;
                goto err_out;
        }
        numbytes = ret;
        ret = -E_AUTH;
        if (strncmp(buf, "auth ", 5))
                goto err_out;

        if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
                u.name = para_strdup(buf + 5); /* client version < 0.2.6 */
        else {
                u.name = para_strdup(buf + 9); /* client version >= 0.2.6 */
                use_rc4 = 1;
        }
        PARA_DEBUG_LOG("received %s request for user %s\n",
                use_rc4? "rc4" : "auth", u.name);
        if ((ret = lookup_user(&u)) < 0)
                goto err_out;
        ret = para_encrypt_challenge(u.rsa, challenge_nr, crypt_buf);
        if (ret <= 0)
                goto err_out;
        numbytes = ret;
        PARA_DEBUG_LOG("sending %d byte challenge\n", numbytes);
        /* We can't use send_buffer here since buf may contain null bytes */
        ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
        if (ret < 0)
                goto err_out;
        /* recv decrypted number */
        numbytes = recv_buffer(fd, buf, sizeof(buf));
        ret = numbytes;
        if (ret < 0)
                goto err_out;
        ret = -E_AUTH;
        if (!numbytes)
                goto err_out;
        if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
                        || chall_response != challenge_nr)
                goto err_out;
        /* auth successful. Send 'Proceed' message */
        PARA_INFO_LOG("good auth for %s (%lu)\n", u.name, challenge_nr);
        sprintf(buf, "%s", PROCEED_MSG);
        if (use_rc4) {
                init_rc4_keys();
                ret = para_encrypt_buffer(u.rsa, rc4_buf, 2 * RC4_KEY_LEN,
                        (unsigned char *)buf + PROCEED_MSG_LEN + 1);
                if (ret <= 0)
                        goto err_out;
                numbytes = ret + strlen(PROCEED_MSG) + 1;
        } else
                numbytes = strlen(buf);
        ret = send_bin_buffer(fd, buf, numbytes);
        if (ret < 0)
                goto err_out;
        if (use_rc4)
                enable_crypt(fd, rc4_recv, rc4_send, NULL);
        /* read command */
        while ((numbytes = recv_buffer(fd, buf, sizeof(buf))) > 0) {
//              PARA_INFO_LOG("recvd: %s (%d)\n", buf, numbytes);
                ret = -E_COMMAND_SYNTAX;
                if (command && numbytes + strlen(command) > STRINGSIZE) /* DOS */
                        goto err_out;
                command = para_strcat(command, buf);
                if ((p = strstr(command, EOC_MSG))) {
                        *p = '\0';
                        break;
                }
        }
        ret = numbytes;
        if (ret < 0)
                goto err_out;
        ret = -E_BAD_CMD;
        /* parse command */
        if (!(cmd = parse_cmd(command)))
                goto err_out;
        /* valid command, check permissions */
        ret = check_perms(u.perms, cmd);
        if (ret < 0)
                goto err_out;
        /* valid command and sufficient perms */
        alarm(0);
        argc = split_args(command, &argv, "\n");
        mmd_lock();
        mmd->num_commands++;
        mmd_unlock();
        PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u.name,
                inet_ntoa(addr->sin_addr));
        ret = cmd->handler(fd, argc, argv);
        if (ret >= 0) {
                ret = EXIT_SUCCESS;
                goto out;
        }
err_out:
        if (ret != -E_SEND && ret != -E_RECV) {
                PARA_NOTICE_LOG("%s\n", PARA_STRERROR(-ret));
                send_va_buffer(fd, "%s\n", PARA_STRERROR(-ret));
        }
        ret = EXIT_FAILURE;
out:
        free(command);
        free(argv);
        mmd_lock();
        if (cmd && (cmd->perms & DB_WRITE) && ret >= 0)
                mmd->events++;
        mmd->active_connections--;
        mmd_unlock();
        return ret;
}