test_cimd2.c

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/* ==================================================================== 
 * The Kannel Software License, Version 1.0 
 * 
 * Copyright (c) 2001-2018 Kannel Group  
 * Copyright (c) 1998-2001 WapIT Ltd.   
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 * 
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 * 
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in 
 *    the documentation and/or other materials provided with the 
 *    distribution. 
 * 
 * 3. The end-user documentation included with the redistribution, 
 *    if any, must include the following acknowledgment: 
 *       "This product includes software developed by the 
 *        Kannel Group (http://www.kannel.org/)." 
 *    Alternately, this acknowledgment may appear in the software itself, 
 *    if and wherever such third-party acknowledgments normally appear. 
 * 
 * 4. The names "Kannel" and "Kannel Group" must not be used to 
 *    endorse or promote products derived from this software without 
 *    prior written permission. For written permission, please  
 *    contact org@kannel.org. 
 * 
 * 5. Products derived from this software may not be called "Kannel", 
 *    nor may "Kannel" appear in their name, without prior written 
 *    permission of the Kannel Group. 
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
 * DISCLAIMED.  IN NO EVENT SHALL THE KANNEL GROUP OR ITS CONTRIBUTORS 
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,  
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT  
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR  
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,  
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE  
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,  
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 * ==================================================================== 
 * 
 * This software consists of voluntary contributions made by many 
 * individuals on behalf of the Kannel Group.  For more information on  
 * the Kannel Group, please see <http://www.kannel.org/>. 
 * 
 * Portions of this software are based upon software originally written at  
 * WapIT Ltd., Helsinki, Finland for the Kannel project.  
 */ 

/* test_cimd2.c - fake cimd2 smsc
 *
 * This program pretends to be an CIMD 2 SMS center, accessible via IP.
 * It is used to test the Kannel smsc_cimd2 code.
 * 
 * Richard Braakman
 */

/* Note: The CIMD2 parsing code was written as a prototype, and currently
 * its main use is to exercise the *real* CIMD2 code in gw/smsc_cimd2.c.
 * Please don't use this code for anything real.
 * Richard Braakman */

/*
 * TODO: If log level is high and activity level is low, there will be
 * "SND" log entries for packets that are not sent, which is confusing
 * and should be fixed.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <stdarg.h>
#include <limits.h>

#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "gwlib/gwlib.h"

enum { TIMESTAMP_MAXLEN = 13 };

unsigned char *progname;

/* Set up a fake account for Kannel to use */
unsigned char *username = "foo";
unsigned char *password = "bar";

int port = 6789;

/* This can be useful to get past protocol-ID checks when testing spew. */
unsigned char *intro = "";

enum ACT {
    ACT_listen = 0,
    ACT_reply = 1,
    ACT_deliver = 2,
    ACT_flood = 3
};

enum SPEW {
    SPEW_nothing = 0,
    SPEW_binary = 1,
    SPEW_characters = 2,
    SPEW_packets = 3
};

enum LOG {
    LOG_nothing = 0,
    LOG_data = 1,
    LOG_packets = 2,
    LOG_sms = 3
};

enum CHK {
    CHK_nothing = 0,
    CHK_packets = 1,
    CHK_sums = 2,
    CHK_protocol = 3,
    CHK_sms = 4
};

int activity = ACT_listen;
int spew = SPEW_nothing;
int logging = LOG_nothing;
int checking = CHK_nothing;

int max_deliveries = -1;
int deliveries = 0;
time_t start_time = 0;

int sockfd = -1;

Octstr *inbuffer;
Octstr *outbuffer;
/* Maximum reasonable outbuffer size.  It can go above this, but we don't
 * deliberately add data when it's already more than this. */
enum { OUTBUFFER_LIMIT = 65536 };

/* Test dependencies on neatly-sized read and write chunks, by using
 * a deliberately evil buffer size.  1021 is the largest prime smaller
 * than 1024. */
enum { EVIL_BUFSIZE = 1021 };


enum CHARS {
    STX = 2,
    ETX = 3,
    TAB = 9,
    LF = 10,
    CR = 13
};

static void usage(FILE *out) {
    fprintf(out, "Usage: %s [options...]\n"
"  --help          Print this message\n"
"  --user USER     Allow clients to log in with username USER (default %s)\n"
"  --password PASS Allow clients to log in with password PASS (default %s)\n"
"  --intro INTRO   Send INTRO string before anything else (default nothing)\n"
"  --port PORT     TCP port to listen on (default %d)\n"
"  --activity ACT  Activity level of test server (default %d)\n"
"      ACT = 0     send nothing, just listen\n"
"      ACT = 1     send valid replies, do not initiate any transactions\n"
"      ACT = 2     attempt to deliver a random SMS every few seconds (NI)\n"
"      ACT = 3     deliver many random SMSes, measure throughput (NI)\n"
"  --spew SPEW     Flood client, overrides --activity (default %d)\n"
"      SPEW = 0    don't spew, use --activity instead\n"
"      SPEW = 1    spew random binary gunk at client\n"
"      SPEW = 2    spew random data of the right character set at client (NI)\n"
"      SPEW = 3    spew valid packets with random contents at client (NI)\n"
"  --logging LOG   Log level of test server (default %d)\n"
"      LOG = 0     log nothing\n"
"      LOG = 1     log all data\n"
"      LOG = 2     log summaries of valid packets\n"
"      LOG = 3     log successfully sent and received SMSes (NI)\n"
"  --checking CHK  Check level of test server (default %d)\n"
"      CHK = 0     check nothing\n"
"      CHK = 1     signal invalid packets (NI)\n"
"      CHK = 2     signal checksum errors (NI)\n"
"      CHK = 3     signal protocol errors (NI)\n"
"      CHK = 4     signal invalid SMS contents (NI)\n"
"  --max MAX       With high activity values, stop after MAX deliveries\n"
" NI means Not Implemented\n"
    , progname, username, password, port,
    activity, spew, logging, checking);
}

static void pretty_print(unsigned char *data, size_t length) {
    size_t i;
    int c;

    for (i = 0; i < length; i++) {
        c = data[i];
        switch(c) {
        default:
            if (isprint(c))
                putchar(c);
            else
                printf("<%d>", c);
            break;
        case TAB: fputs("<TAB>", stdout); break;
        case LF: fputs("<LF>\n", stdout); break;
        case CR: fputs("<CR>", stdout); break;
        case STX: fputs("<STX>", stdout); break;
        case ETX: fputs("<ETX>\n", stdout); break;
        }
    }
    fflush(stdout);
}

static void read_data(Octstr *in, int fd) {
    unsigned char buf[EVIL_BUFSIZE];
    int ret;

    ret = read(fd, buf, sizeof(buf));
    if (ret > 0) {
        octstr_append_data(in, buf, ret);
        if (logging == LOG_data)
            pretty_print(buf, ret);
    } else if (ret == 0) {
        fprintf(stderr, "Client closed socket\n");
        exit(0);
    } else {
        if (errno == EINTR || errno == EAGAIN)
            return;
        error(errno, "read_data");
        exit(1);
    }
}

static void write_data(Octstr *out, int fd) {
    unsigned char buf[EVIL_BUFSIZE];
    int len;
    ssize_t ret;
    
    len = sizeof(buf);
    if (len > octstr_len(out))
        len = octstr_len(out);
    if (len == 0)
        return;
    octstr_get_many_chars(buf, out, 0, len);
    ret = write(fd, buf, len);
    if (ret > 0) {
        if (logging == LOG_data)
            pretty_print(buf, ret);
        octstr_delete(out, 0, ret);
    } else if (ret == 0) {
        warning(0, "empty write");
    } else {
        if (errno == EINTR || errno == EAGAIN)
            return;
        error(errno, "write_data");
        exit(1);
    }
}

static void gen_message(Octstr *out);

/* Return the minimum interval (in microseconds) after which we will
 * want to be called again.  This value is only used if we _don't_
 * generate data this time through. */
static long gen_data(Octstr *out) {
    unsigned char buf[EVIL_BUFSIZE];
    size_t i;
    long interval = -1;
    static int last_sms;  /* Used by ACT_deliver */
    time_t now;

    if (max_deliveries < 0 || deliveries < max_deliveries) {
        switch (activity) {
        case ACT_deliver:
            now = time(NULL);
            if (last_sms == 0)
                last_sms = now;
            while (last_sms < now) {
                if (random() % 7 == 1) {
                    gen_message(out);
                    last_sms = now;
                } else
                    last_sms++;
            }
            interval = 1000000;
            break;
        case ACT_flood:
            gen_message(out);
            break;
        }
    }

    switch (spew) {
    case SPEW_binary:
        for (i = 0; i < sizeof(buf); i++) {
            buf[i] = random() % 256;
        }
        octstr_append_data(out, buf, sizeof(buf));
        break;
    }

    return interval;
}

/******************************* CIMD 2 specific code ************************/

int awaiting_response = 0;

/* buf must be at least TIMESTAMP_MAXLEN bytes long. */
static void make_timestamp(unsigned char *buf, time_t fortime) {
    /* Is there a thread-safe version of gmtime? */
    struct tm tm = gw_gmtime(fortime);

    sprintf(buf, "%02d%02d%02d%02d%02d%02d",
        tm.tm_year % 100, tm.tm_mon + 1, tm.tm_mday,
        tm.tm_hour, tm.tm_min, tm.tm_sec);
}
    

static void send_packet(Octstr *out, int opcode, int sequence, ...) {
    va_list ap;
    int parm;
    unsigned char *value;
    int checksum;
    int old_len, new_len;

    if (activity == ACT_listen)
        return;

    old_len = octstr_len(out);

    octstr_format_append(out, "%c%02d:%03d%c", STX, opcode, sequence, TAB);

    va_start(ap, sequence);
    for (parm = va_arg(ap, int); parm != 0; parm = va_arg(ap, int)) {
        value = va_arg(ap, unsigned char *);
        octstr_format_append(out, "%03d:%s\11", parm, value);
    }
    va_end(ap);

    /* Calculate checksum */
    checksum = 0;
    for (new_len = octstr_len(out); old_len < new_len; old_len++) {
        checksum = (checksum + octstr_get_char(out, old_len)) & 0xff;
    }

    octstr_format_append(out, "%02X%c", checksum, ETX);
}

static void send_error(Octstr *out, int opcode, int sequence,
            unsigned char *errorcode, unsigned char *errortext) {
    if (logging == LOG_packets)
        printf("SND: ERROR, %s\n", errortext);

    send_packet(out, opcode, sequence, 900, errorcode, 901, errortext, 0);
}

static int eat_char(Octstr *packet, int ch) {
    if (octstr_get_char(packet, 0) == ch) {
        octstr_delete(packet, 0, 1);
        return 0;
    }
    return -1;
}

static Octstr *eat_string_parm(Octstr *packet, int parm, int maxlen) {
    long start, datastart;
    long tab;
    Octstr *result;
    Octstr *parmheader;

        parmheader = octstr_format("%c%03d:", TAB, parm);
    start = octstr_search(packet, parmheader, 0);
    if (start < 0) {
        octstr_destroy(parmheader);
        return NULL;
    }
    datastart = start + octstr_len(parmheader);

    tab = octstr_search_char(packet, TAB, datastart + 1);
    if (tab < 0) {
        tab = octstr_len(packet);
    }

    result = octstr_copy(packet, datastart, tab - datastart);
    octstr_delete(packet, start, tab - start);
    octstr_destroy(parmheader);
    return result;
}

static long eat_number(Octstr *ostr) {
    long result;
    long pos;

    pos = octstr_parse_long(&result, ostr, 0, 10);
    if (pos < 0)
        return INT_MIN;

    octstr_delete(ostr, 0, pos);
    return result;
}

static long eat_int_parm(Octstr *packet, int parm, int maxlen) {
    Octstr *value;
    long result;

    value = eat_string_parm(packet, parm, maxlen);
    if (!value)
        return INT_MIN;

    result = eat_number(value);
    if (octstr_len(value) > 0)
        result = INT_MIN;

    octstr_destroy(value);
    return result;
}

static void eat_checksum(Octstr *packet) {
    int len;
    int ch1, ch2, ch3;

    len = octstr_len(packet);

    if (len < 3)
        return;

    ch1 = octstr_get_char(packet, len - 3);
    ch2 = octstr_get_char(packet, len - 2);
    ch3 = octstr_get_char(packet, len - 1);
    
    if (isxdigit(ch3) && isxdigit(ch2) && ch1 == TAB)
        octstr_delete(packet, len - 3, 3);
}

static void handle_login(Octstr *packet, Octstr *out, int sequence) {
    Octstr *user = eat_string_parm(packet, 10, 32);
    Octstr *pass = eat_string_parm(packet, 11, 32);

    if (user == NULL)
        user = octstr_create("");
    if (pass == NULL)
        pass = octstr_create("");

    if (logging == LOG_packets)
        printf("RCV: Login user '%s', password '%s'\n",
            octstr_get_cstr(user), octstr_get_cstr(pass));

    if (octstr_str_compare(user, username) == 0 &&
        octstr_str_compare(pass, password) == 0) {
        if (logging == LOG_packets)
            printf("SND: Login OK\n");
        send_packet(out, 51, sequence, 0);
    } else {
        send_error(out, 51, sequence, "100", "invalid login");
    }

    octstr_destroy(user);
    octstr_destroy(pass);
}

static void handle_logout(Octstr *packet, Octstr *out, int sequence) {
    if (logging == LOG_packets)
        printf("RCV: Logout\n");
    if (logging == LOG_packets)
        printf("SND: Logout OK\n");
    send_packet(out, 52, sequence, 0);
}

static void handle_submit(Octstr *packet, Octstr *out, int sequence) {
    Octstr *dest_addr = eat_string_parm(packet, 21, 20);
    Octstr *orig_addr = eat_string_parm(packet, 23, 20);
    long DCS = eat_int_parm(packet, 30, 3);
    Octstr *UDH = eat_string_parm(packet, 32, 280);
    Octstr *text = eat_string_parm(packet, 33, 480);
    Octstr *textb = eat_string_parm(packet, 34, 280);
    long valid_rel = eat_int_parm(packet, 50, 3);
    Octstr *valid_abs = eat_string_parm(packet, 51, 12);
    long proto_id = eat_int_parm(packet, 52, 3);
    long delivery_rel = eat_int_parm(packet, 53, 3);
    Octstr *delivery_abs = eat_string_parm(packet, 54, 12);
    long reply_path = eat_int_parm(packet, 55, 1);
    long SRR = eat_int_parm(packet, 56, 2);
    long cancel = eat_int_parm(packet, 58, 1);
    long tariff_class = eat_int_parm(packet, 64, 2);
    long service_desc = eat_int_parm(packet, 65, 1);
    long priority = eat_int_parm(packet, 67, 1);
    List *other_dests = gwlist_create();
    Octstr *tmp;

    while ((tmp = eat_string_parm(packet, 21, 20)))
        gwlist_append(other_dests, tmp);

    if (logging == LOG_packets) {
        int i;
        printf("RCV: Submit to %s", octstr_get_cstr(dest_addr));
        for (i = 0; i < gwlist_len(other_dests); i++) {
            printf(", %s",
                octstr_get_cstr(gwlist_get(other_dests, i)));
        }
        printf("\n");

        if (orig_addr)
            printf("    From: %s\n", octstr_get_cstr(orig_addr));
        if (DCS > INT_MIN)
            printf("    Data coding: %ld\n", DCS);
        if (UDH)
            printf("    User data header: %s\n",
                octstr_get_cstr(UDH));
        if (text)
            printf("    Text: %s\n", octstr_get_cstr(text));
        if (textb)
            printf("    Text (binary): %s\n",
                octstr_get_cstr(textb));
        if (valid_rel > INT_MIN)
            printf("    Validity period: %ld (relative)\n",
                valid_rel);
        if (valid_abs)
            printf("    Validity period: %s (absolute)\n",
                octstr_get_cstr(valid_abs));
        if (proto_id > INT_MIN)
            printf("    Protocol ID: %ld\n", proto_id);
        if (delivery_rel > INT_MIN)
            printf("    First delivery: %ld (relative)\n",
                delivery_rel);
        if (delivery_abs)
            printf("    First delivery: %s (absolute)\n",
                octstr_get_cstr(delivery_abs));
        if (reply_path == 0)
            printf("    Reply path disabled\n");
        else if (reply_path == 1)
            printf("    Reply path enabled\n");
        else if (reply_path > INT_MAX)
            printf("    Reply path: %ld\n", reply_path);
        if (SRR > INT_MAX)
            printf("    Status report flags: %ld\n", SRR);
        if (cancel == 0)
            printf("    Cancel disabled\n");
        else if (cancel == 1)
            printf("    Cancel enabled\n");
        else if (cancel > INT_MAX)
            printf("    Cancel enabled: %ld\n", cancel);
        if (tariff_class > INT_MAX)
            printf("    Tariff class: %ld\n", tariff_class);
        if (service_desc > INT_MAX)
            printf("    Service description: %ld\n", service_desc);
        if (priority > INT_MAX)
            printf("    Priority: %ld\n", priority);
    }

    if (!dest_addr) {
        send_error(out, 53, sequence, "300", "no destination");
    } else if (gwlist_len(other_dests) > 0) {
        send_error(out, 53, sequence, "301", "too many destinations");
    /* TODO: Report many other possible errors here */
    } else {
        unsigned char buf[TIMESTAMP_MAXLEN];

        make_timestamp(buf, time(NULL));
        if (logging == LOG_packets)
            printf("SND: Submit OK\n");
        send_packet(out, 53, sequence,
                    21, octstr_get_cstr(dest_addr),
                60, buf,
                0);
    }

    octstr_destroy(dest_addr);
    octstr_destroy(orig_addr);
    octstr_destroy(UDH);
    octstr_destroy(text);
    octstr_destroy(textb);
    octstr_destroy(valid_abs);
    octstr_destroy(delivery_abs);
    gwlist_destroy(other_dests, octstr_destroy_item);
}

static void handle_enquire(Octstr *packet, Octstr *out, int sequence) {
    Octstr *dest_addr = eat_string_parm(packet, 21, 20);
    Octstr *timestamp = eat_string_parm(packet, 60, 12);

    if (logging == LOG_packets)
        printf("RCV: Enquire status, dest='%s', time='%s'\n",
            dest_addr ? octstr_get_cstr(dest_addr) : "",
            timestamp ? octstr_get_cstr(timestamp) : "");

    if (!dest_addr) {
        send_error(out, 54, sequence, "400", "no destination");
    } else if (!timestamp) {
        send_error(out, 54, sequence, "401", "no timestamp");
    } else {
        if (logging == LOG_packets)
            printf("SND: Respond: status unknown\n");
        send_packet(out, 54, sequence,
                21, octstr_get_cstr(dest_addr),
                60, octstr_get_cstr(timestamp),
                61, "0",
                0);
    }
    octstr_destroy(dest_addr);
    octstr_destroy(timestamp);
}

static void handle_delivery_request(Octstr *packet, Octstr *out, int sequence) {
    long mode = eat_int_parm(packet, 68, 1);

    if (logging == LOG_packets) {
        switch (mode) {
        case 0: printf("RCV: Delivery request, messages waiting?\n");
            break;
        case 1: printf("RCV: Delivery request, one message\n");
            break;
        case 2: printf("RCV: Delivery request, all messages\n");
            break;
        case INT_MIN:
            printf("RCV: Delivery request, no mode\n");
            break;
        default:
            printf("RCV: Delivery request, mode %ld\n", mode);
        }
    }

    if (mode == INT_MIN)
        mode = 1;

    switch (mode) {
    case 0:
        if (logging == LOG_packets)
            printf("SND: Respond: 0 messages\n");
        send_packet(out, 55, sequence,
                66, "0",
                0);
        break;

    case 1:
        send_error(out, 55, sequence, "500", "no messages available");
        break;

    case 2:
        send_error(out, 55, sequence, "500", "no messages available");
        break;

    default:
        send_error(out, 55, sequence, "501", "bad mode");
        break;
    }
}

static void handle_cancel(Octstr *packet, Octstr *out, int sequence) {
    long mode = eat_int_parm(packet, 59, 1);
    Octstr *timestamp = eat_string_parm(packet, 60, 12);
    Octstr *destination = eat_string_parm(packet, 21, 20);

    if (logging == LOG_packets) {
        printf("RCV: Cancel");
        if (mode != INT_MIN)
            printf(", mode %ld", mode);
        if (destination)
            printf(", dest '%s'", octstr_get_cstr(destination));
        if (timestamp)
            printf(", time '%s'", octstr_get_cstr(timestamp));
        printf("\n");
    }

    if (mode < 0 || mode > 2)
        send_error(out, 56, sequence, "602", "bad mode");
    else {
        if (logging == LOG_packets)
            printf("SND: OK\n");
        send_packet(out, 56, sequence, 0);
    }
}


static void handle_set(Octstr *packet, Octstr *out, int sequence) {
    Octstr *pass = eat_string_parm(packet, 11, 32);

    if (pass) {
        if (logging == LOG_packets)
            printf("RCV: Set password to '%s'\n",
                octstr_get_cstr(pass));
        send_error(out, 58, sequence,
            "801", "changing password not allowed");
    } else {
        if (logging == LOG_packets)
            printf("RCV: Set, unknown parameters\n");
        send_error(out, 58, sequence, "3", "cannot set");
    }
}


static void handle_get(Octstr *packet, Octstr *out, int sequence) {
    long number = eat_int_parm(packet, 500, 3);

    if (logging == LOG_packets)
        printf("RCV: Get parameter #%ld\n", number);

    if (number == INT_MIN) {
        send_error(out, 59, sequence, "900", "missing parameter");
    } else if (number == 501) {
        unsigned char buf[TIMESTAMP_MAXLEN];
        make_timestamp(buf, time(NULL));
        if (logging == LOG_packets)
            printf("SND: OK, SMSC timestamp is '%s'\n", buf);
        send_packet(out, 59, sequence,
                501, buf,
                0);
    } else {
        send_error(out, 59, sequence, "900", "unknown parameter");
    }
}

static void handle_alive(Octstr *packet, Octstr *out, int sequence) {
    if (logging == LOG_packets)
        printf("RCV: Alive?\n");
    if (logging == LOG_packets)
        printf("SND: Alive.\n");
    send_packet(out, 90, sequence, 0);
}

static void handle_deliver_response(Octstr *packet, Octstr *out, int sequence) {
    awaiting_response = 0;
    if (logging == LOG_packets)
        printf("RCV: Deliver response\n");
    deliveries++;
    if (max_deliveries > 0 && deliveries == max_deliveries) {
        time_t elapsed = time(NULL) - start_time;
        printf("LOG: %ld deliveries in %ld seconds\n",
            (long) max_deliveries, (long) elapsed);
    }
    /* No need to respond to a response */
}

static void handle_deliver_status_report_response(Octstr *packet, Octstr *out, int sequence) {
    awaiting_response = 0;
    if (logging == LOG_packets)
        printf("RCV: Deliver status report response\n");
    /* No need to respond to a response */
}

static void handle_alive_response(Octstr *packet, Octstr *out, int sequence) {
    awaiting_response = 0;
    if (logging == LOG_packets)
        printf("RCV: Alive.\n");
    /* No need to respond to a response */
}

static void handle_nack(Octstr *packet, Octstr *out, int sequence) {
    awaiting_response = 0;
    if (logging == LOG_packets)
        printf("RCV: NACK\n");
    /* TODO: We should retransmit if we get a nack, but there's
     * no record of what request we sent. */
}

typedef void (*packet_handler)(Octstr *, Octstr *, int);

struct {
    int opcode;
    packet_handler handler;
} handlers[] = {
    { 1, handle_login },
    { 2, handle_logout },
    { 3, handle_submit },
    { 4, handle_enquire },
    { 5, handle_delivery_request },
    { 6, handle_cancel },
    { 8, handle_set },
    { 9, handle_get },
    { 40, handle_alive },
    { 70, handle_deliver_response },
    { 73, handle_deliver_status_report_response },
    { 90, handle_alive_response },
    { 99, handle_nack },
    { -1, NULL },
};

static void parse_packet(Octstr *packet, Octstr *out) {
    int opcode, sequence;
    int i;

    eat_checksum(packet);

    opcode = eat_number(packet);
    if (opcode < 0 || eat_char(packet, ':') < 0)
        return;
    sequence = eat_number(packet);
    if (sequence < 0)
        return;

    for (i = 0; handlers[i].opcode >= 0; i++) {
        if (handlers[i].opcode == opcode) {
            (handlers[i].handler)(packet, out, sequence);
            break;
        }
    }

    if (handlers[i].opcode < 0) { /* Loop failed */
        if (logging == LOG_packets)
            printf("RCV: unknown operation %ld\n",
                (long) handlers[i].opcode);
        send_error(out, 98, sequence, "1", "unexpected operation");
    }
}

/* Parse the data stream for packets, and send out replies. */
static void parse_data(Octstr *in, Octstr *out) {
    int stx, etx;
    Octstr *packet;

    for (;;) {
        /* Look for start of packet.  Delete everything up to the start
         * marker.  (CIMD2 section 3.1 says we can ignore any data
         * transmitted between packets.) */
        stx = octstr_search_char(in, STX, 0);
        if (stx < 0)
            octstr_delete(in, 0, octstr_len(in));
        else if (stx > 0)
            octstr_delete(in, 0, stx);

        etx = octstr_search_char(in, ETX, 0);
        if (etx < 0)
            return;  /* Incomplete packet; wait for more data. */

        /* Copy the data between stx and etx */
        packet = octstr_copy(in, 1, etx - 1);
        /* Then cut the packet (including stx and etx) from inbuffer */
        octstr_delete(in, 0, etx + 1);

        parse_packet(packet, out);

        octstr_destroy(packet);
    }
}

static void random_address(unsigned char *buf, int size) {
    int len = random() % size;

    while (len--) {
        *buf++ = '0' + random() % 10;
    }

    *buf++ = '\0';
}

static void random_message(unsigned char *buf, int size) {
    int len = random() % size;

    while (len--) {
        do {
            *buf = random() % 256;
        } while (*buf == STX || *buf == ETX || *buf == TAB);
        buf++;
    }

    *buf++ = '\0';
}

static void random_hex(unsigned char *buf, int size) {
    int len = random() % size;

    /* Make even */
    len -= (len % 2);

    while (len--) {
        int c = random() % 16;
        if (c < 10)
            *buf++ = c + '0';
        else
            *buf++ = c - 10 + 'a';
    }

    *buf++ = '\0';
}

static void gen_message(Octstr *out) {
    static int send_seq = 0;
    unsigned char dest[21];
    unsigned char orig[21];
    unsigned char scts[TIMESTAMP_MAXLEN];
    unsigned char message[481];
    unsigned char udh[281];

    if (awaiting_response == 1)
        return;

    random_address(dest, sizeof(dest));
    random_address(orig, sizeof(orig));
    make_timestamp(scts, time(NULL));
    random_message(message, sizeof(message));
    if (random() % 2 == 0)
        random_hex(udh, sizeof(udh));
    else
        *udh = 0;

    if (logging == LOG_packets)
        printf("SND: Deliver message (random)\n");

    if (*udh) {
        send_packet(out, 20, send_seq,
            21, dest,
            23, orig,
            60, scts,
            32, udh,
            33, message,
            0);
    } else {
        send_packet(out, 20, send_seq,
            21, dest,
            23, orig,
            60, scts,
            33, message,
            0);
    }

    send_seq += 2;
    if (send_seq > 255)
        send_seq = 0;

    awaiting_response = 1;
}

/************************** CIMD 2 specific code ends ************************/

static void main_loop(void) {
    fd_set readfds, writefds;
    int n;
    static int reported_outfull = 0;
    int interval = -1;

    inbuffer = octstr_create("");
    outbuffer = octstr_create(intro);
    start_time = time(NULL);

    for (;;) {
        if (octstr_len(outbuffer) < OUTBUFFER_LIMIT) {
            interval = gen_data(outbuffer);
        } else if (!reported_outfull) {
            warning(0, "outbuffer getting full; waiting...");
            reported_outfull = 1;
        }

        FD_ZERO(&readfds);
        FD_SET(sockfd, &readfds);

        if (octstr_len(outbuffer) > 0) {
            FD_ZERO(&writefds);
            FD_SET(sockfd, &writefds);
            n = select(sockfd+1, &readfds, &writefds, NULL, NULL);
        } else {
            struct timeval tv;
            struct timeval *tvp;

            if (interval >= 0) {
                tv.tv_sec = 0;
                tv.tv_usec = interval;
                tvp = &tv;
            } else {
                tvp = NULL;
            }
            n = select(sockfd+1, &readfds, NULL, NULL, tvp);
        }

        if (n < 0) {
            if (errno == EINTR) {
                warning(errno, "main loop, select");
                continue;
            }
            error(errno, "main loop, select");
            sleep(1);
            continue;
        }
        if (n > 0) {
            if (FD_ISSET(sockfd, &readfds)) {
                read_data(inbuffer, sockfd);
                parse_data(inbuffer, outbuffer);
            }
            if (octstr_len(outbuffer) > 0 &&
                FD_ISSET(sockfd, &writefds)) {
                write_data(outbuffer, sockfd);
            }
            if (octstr_len(outbuffer) < OUTBUFFER_LIMIT) {
                reported_outfull = 0;
            }
        }
    }
}

static struct {
    unsigned char *option;
    void *location;
    int number;
} options[] = {
    { "--user", &username, 0 },
    { "--password", &password, 0 },
    { "--port", &port, 1 },
    { "--intro", &intro, 0 },
    { "--activity", &activity, 1 },
    { "--spew", &spew, 1 },
    { "--logging", &logging, 1 },
    { "--checking", &checking, 1 },
    { "--max", &max_deliveries, 1 },
    { NULL, NULL, 0 },
};

static int wait_for_client(int port) {
    struct sockaddr_in sin;
    socklen_t addrlen;
    int listenfd;
    int clientfd;
    Octstr *addr;

    listenfd = make_server_socket(port, NULL);
    if (listenfd < 0) {
        fprintf(stderr, "%s: failed to open socket at port %d\n",
            progname, port);
        exit(1);
    }

    do {
        addrlen = sizeof(sin);
        clientfd = accept(listenfd, (struct sockaddr *)&sin, &addrlen);
        if (clientfd < 0) {
            error(errno, "failed to accept new connection");
        }
    } while (clientfd < 0);

    if (socket_set_blocking(clientfd, 0) < 0) {
        panic(0, "failed to make client socket nonblocking");
    }

        addr = gw_netaddr_to_octstr(AF_INET, &sin.sin_addr);
    info(0, "Accepted client from %s:%d",
        octstr_get_cstr(addr), ntohs(sin.sin_port));
        octstr_destroy(addr);

    close(listenfd);

    return clientfd;
}
    

int main(int argc, char *argv[]) {
    int i;
    int opt;

    gwlib_init();

    progname = argv[0];
    srandom(0);  /* Make "random" data reproducible */

    for (i = 1; i < argc; i++) {
        for (opt = 0; options[opt].option; opt++) {
            if (strcmp(argv[i], options[opt].option) == 0) {
                if (i + 1 >= argc) {
                    fprintf(stderr, "%s: missing argument to %s",
                        progname, argv[i]);
                    exit(2);
                }
                if (options[opt].number) {
                    * (int *) options[opt].location = atoi(argv[i+1]);
                } else {
                    * (char **) options[opt].location = argv[i+1];
                }
                i++;
                break;
            }
        }
        if (options[opt].option)
            continue;
        if (strcmp(argv[i], "--help") == 0) {
            usage(stdout);
            exit(0);
        }
        if (argv[i][0] == '-') {
            fprintf(stderr, "%s: unknown option %s\n",
                progname, argv[i]);
            usage(stderr);
            exit(2);
        }
    }

    sockfd = wait_for_client(port);
    main_loop();
    return 0;
}