/*

  mybot.c

  Author: Pekka Riikonen <priikone@silcnet.org>, November 2002, 2007
  This code is Public Domain.

  MyBot

  Example SILC client called "mybot".  It is a robot client which
  connects to SILC Network into silc.silcnet.org server and joins
  channel called "mybot" and says "hello" on the channel.

  This code use the SILC Client Library provided by the SILC
  Toolkit distribution.

  Compilation:

  gcc -o mybot mybot.c -I/usr/local/silc/include -L/usr/local/silc/lib \
      -lsilc -lsilcclient -lpthread -ldl

*/

#include "silc.h"		/* Mandatory include for SILC applications */
#include "silcclient.h"		/* SILC Client Library API */

SilcClientOperations ops;

static void silc_running(SilcClient client, void *application);
static void silc_stopped(SilcClient client, void *context);

/******* MyBot code **********************************************************/

/* This is context for our MyBot client */
typedef struct {
  SilcClient client;		/* The actual SILC Client */
  SilcClientConnection conn;	/* Connection to the server */
  SilcPublicKey public_key;     /* My public key */
  SilcPrivateKey private_key;   /* My private key */
} *MyBot;

/* Connect callback called after connected to remote server. */

static void
silc_connected(SilcClient client, SilcClientConnection conn,
	       SilcClientConnectionStatus status,
	       SilcStatus error, const char *message,
	       void *context)
{
  MyBot mybot = client->application;

  if (status == SILC_CLIENT_CONN_DISCONNECTED) {
    SILC_LOG_DEBUG(("Disconnected %s", message ? message : ""));
    silc_client_stop(client, silc_stopped, mybot);
    return;
  }

  if (status != SILC_CLIENT_CONN_SUCCESS &&
      status != SILC_CLIENT_CONN_SUCCESS_RESUME) {
    SILC_LOG_DEBUG(("Error connecting to server %d", status));
    silc_client_stop(client, silc_stopped, mybot);
    return;
  }

  fprintf(stdout, "\nMyBot: Connected to server\n\n");

  /* Now that we have connected to server, let's join a channel named
     "mybot". */
  silc_client_command_call(client, conn, "JOIN mybot");

  /* Save the connection context */
  mybot->conn = conn;
}

/* Running callback given to silc_client_init called to indicate that the
   Client Library is running.  After this Client API functions can be
   called. */

static void silc_running(SilcClient client, void *application)
{
  MyBot mybot = application;

  SILC_LOG_DEBUG(("Client is running"));

  /* Connect to server.  The silc_connected callback will be called after
     the connection is established or if an error occurs during connecting. */
  silc_client_connect_to_server(mybot->client, NULL,
				mybot->public_key, mybot->private_key,
				"silc.silcnet.org", 706,
				silc_connected, mybot);
}

/* Client stopped callback given to silc_client_stop.  Called to indicate
   that Client Library is stopped. */

static void silc_stopped(SilcClient client, void *context)
{
  SILC_LOG_DEBUG(("Client stopped"));
}

/* Start the MyBot, by creating the SILC Client entity by using the
   SILC Client Library API. */
int mybot_start(void)
{
  MyBot mybot;
  SilcClientParams params;

  /* Allocate the MyBot structure */
  mybot = silc_calloc(1, sizeof(*mybot));
  if (!mybot) {
    perror("Out of memory");
    return 1;
  }

  memset(&params, 0, sizeof(params));
  params.threads = TRUE;
  mybot->client = silc_client_alloc(&ops, &params, mybot, NULL);
  if (!mybot->client) {
    perror("Could not allocate SILC Client");
    return 1;
  }

  /* Now we initialize the client. */
  if (!silc_client_init(mybot->client, silc_get_username(),
			silc_net_localhost(), "I am the MyBot",
			silc_running, mybot)) {
    perror("Could not init client");
    return 1;
  }

  if (!silc_load_key_pair("mybot.pub", "mybot.prv", "",
			  &mybot->public_key,
			  &mybot->private_key)) {
    /* The keys don't exist.  Let's generate us a key pair then!  There's
       nice ready routine for that too.  Let's do 2048 bit RSA key pair. */
    fprintf(stdout, "MyBot: Key pair does not exist, generating it.\n");
    if (!silc_create_key_pair("rsa", 2048, "mybot.pub", "mybot.prv", NULL, "",
			      &mybot->public_key,
			      &mybot->private_key, FALSE)) {
      perror("Could not generated key pair");
      return 1;
    }
  }

  /* And, then we are ready to go.  Since we are really simple client we
     don't have user interface and we don't have to deal with message loops
     or interactivity.  That's why we can just hand over the execution
     to the library by calling silc_client_run.  */
  silc_client_run(mybot->client);

  /* When we get here, we have quit the client, so clean up and exit */
  silc_client_free(mybot->client);
  silc_free(mybot);
  return 0;
}

/******* SILC Client Operations **********************************************/

/* The SILC Client Library requires these "client operations".  They are
   functions that the library may call at any time to indicate to application
   that something happened, like message was received, or authentication
   is required or something else.  Since our MyBot is really simple client
   we don't need most of the operations, so we just define them and don't
   do anything in them. */

/* "say" client operation is a message from the client library to the
   application.  It may include error messages or something else.  We
   just dump them to screen. */

static void
silc_say(SilcClient client, SilcClientConnection conn,
	 SilcClientMessageType type, char *msg, ...)
{
  char str[200];
  va_list va;
  va_start(va, msg);
  vsnprintf(str, sizeof(str) - 1, msg, va);
  fprintf(stdout, "MyBot: %s\n", str);
  va_end(va);
}


/* Message for a channel. The `sender' is the sender of the message
   The `channel' is the channel. The `message' is the message.  Note
   that `message' maybe NULL.  The `flags' indicates message flags
   and it is used to determine how the message can be interpreted
   (like it may tell the message is multimedia message). */

static void
silc_channel_message(SilcClient client, SilcClientConnection conn,
		     SilcClientEntry sender, SilcChannelEntry channel,
		     SilcMessagePayload payload,
		     SilcChannelPrivateKey key,
		     SilcMessageFlags flags, const unsigned char *message,
		     SilcUInt32 message_len)
{
  /* Yay! We got a message from channel. */

  if (flags & SILC_MESSAGE_FLAG_SIGNED)
    fprintf(stdout, "[SIGNED] <%s> %s\n", sender->nickname, message);
  else
    fprintf(stdout, "<%s> %s\n", sender->nickname, message);
}


/* Private message to the client. The `sender' is the sender of the
   message. The message is `message'and maybe NULL.  The `flags'
   indicates message flags  and it is used to determine how the message
   can be interpreted (like it may tell the message is multimedia
   message). */

static void
silc_private_message(SilcClient client, SilcClientConnection conn,
		     SilcClientEntry sender, SilcMessagePayload payload,
		     SilcMessageFlags flags,
		     const unsigned char *message,
		     SilcUInt32 message_len)
{
  /* MyBot does not support private message receiving */
}


/* Notify message to the client. The notify arguments are sent in the
   same order as servers sends them. The arguments are same as received
   from the server except for ID's.  If ID is received application receives
   the corresponding entry to the ID. For example, if Client ID is received
   application receives SilcClientEntry.  Also, if the notify type is
   for channel the channel entry is sent to application (even if server
   does not send it because client library gets the channel entry from
   the Channel ID in the packet's header). */

static void
silc_notify(SilcClient client, SilcClientConnection conn,
	    SilcNotifyType type, ...)
{
  char *str;
  va_list va;

  va_start(va, type);

  /* Here we can receive all kinds of different data from the server, but
     our simple bot is interested only in receiving the "not-so-important"
     stuff, just for fun. :) */
  switch (type) {
  case SILC_NOTIFY_TYPE_NONE:
    /* Received something that we are just going to dump to screen. */
    str = va_arg(va, char *);
    fprintf(stdout, "--- %s\n", str);
    break;

  case SILC_NOTIFY_TYPE_MOTD:
    /* Received the Message of the Day from the server. */
    str = va_arg(va, char *);
    fprintf(stdout, "%s", str);
    fprintf(stdout, "\n");
    break;

  default:
    /* Ignore rest */
    break;
  }

  va_end(va);
}


/* Command handler. This function is called always in the command function.
   If error occurs it will be called as well. `conn' is the associated
   client connection. `cmd_context' is the command context that was
   originally sent to the command. `success' is FALSE if error occurred
   during command. `command' is the command being processed. It must be
   noted that this is not reply from server. This is merely called just
   after application has called the command. Just to tell application
   that the command really was processed. */

static void
silc_command(SilcClient client, SilcClientConnection conn,
	     SilcBool success, SilcCommand command, SilcStatus status,
	     SilcUInt32 argc, unsigned char **argv)
{
  /* If error occurred in client library with our command, print the error */
  if (status != SILC_STATUS_OK)
    fprintf(stderr, "MyBot: COMMAND %s: %s\n",
	    silc_get_command_name(command),
	    silc_get_status_message(status));
}


/* Command reply handler. This function is called always in the command reply
   function. If error occurs it will be called as well. Normal scenario
   is that it will be called after the received command data has been parsed
   and processed. The function is used to pass the received command data to
   the application.

   `conn' is the associated client connection. `cmd_payload' is the command
   payload data received from server and it can be ignored. It is provided
   if the application would like to re-parse the received command data,
   however, it must be noted that the data is parsed already by the library
   thus the payload can be ignored. `success' is FALSE if error occurred.
   In this case arguments are not sent to the application. The `status' is
   the command reply status server returned. The `command' is the command
   reply being processed. The function has variable argument list and each
   command defines the number and type of arguments it passes to the
   application (on error they are not sent). */

static void
silc_command_reply(SilcClient client, SilcClientConnection conn,
		   SilcCommand command, SilcStatus status,
		   SilcStatus error, va_list ap)
{
  /* If error occurred in client library with our command, print the error */
  if (status != SILC_STATUS_OK)
    fprintf(stderr, "MyBot: COMMAND REPLY %s: %s\n",
	    silc_get_command_name(command),
	    silc_get_status_message(status));

  /* Check for successful JOIN.  See
     http://silcnet.org/docs/toolkit/command_reply_args.html for the
     different arguments the client library returns. */
  if (command == SILC_COMMAND_JOIN) {
    SilcChannelEntry channel;
    SilcHash sha1hash;

    (void)va_arg(ap, SilcClientEntry);
    channel = va_arg(ap, SilcChannelEntry);

    fprintf(stdout, "MyBot: Joined '%s' channel\n", channel->channel_name);

    /* Now send the "hello" to the channel */
    silc_client_send_channel_message(client, conn, channel, NULL, 0, NULL,
				     "hello", strlen("hello"));
    fprintf(stdout, "MyBot: Sent 'hello' to channel\n");

    /* Now send digitally signed "hello" to the channel.  We have to allocate
       hash function for the signature process. */
    silc_hash_alloc("sha1", &sha1hash);
    silc_client_send_channel_message(client, conn, channel, NULL,
				     SILC_MESSAGE_FLAG_SIGNED, sha1hash,
				     "hello, with signature",
				     strlen("hello, with signature"));
    silc_hash_free(sha1hash);
    fprintf(stdout, "MyBot: Sent 'hello, with signature' to channel\n");
  }
}

/* Find authentication method and authentication data by hostname and
   port. The hostname may be IP address as well. When the authentication
   method has been resolved the `completion' callback with the found
   authentication method and authentication data is called. The `conn'
   may be NULL. */

static void
silc_get_auth_method(SilcClient client, SilcClientConnection conn,
		     char *hostname, SilcUInt16 port,
		     SilcAuthMethod auth_method,
		     SilcGetAuthMeth completion,
		     void *context)
{
  /* MyBot assumes that there is no authentication requirement in the
     server and sends nothing as authentication.  We just reply with
     TRUE, meaning we know what is the authentication method. :). */
  completion(SILC_AUTH_NONE, NULL, 0, context);
}


/* Verifies received public key. The `conn_type' indicates which entity
   (server, client etc.) has sent the public key. If user decides to trust
   the application may save the key as trusted public key for later
   use. The `completion' must be called after the public key has been
   verified. */

static void
silc_verify_public_key(SilcClient client, SilcClientConnection conn,
		       SilcConnectionType conn_type,
	 	       SilcPublicKey public_key,
		       SilcVerifyPublicKey completion, void *context)
{
  fprintf(stdout, "MyBot: server's public key\n");
  silc_show_public_key(public_key);
  completion(TRUE, context);
}


/* Ask (interact, that is) a passphrase from user. The passphrase is
   returned to the library by calling the `completion' callback with
   the `context'. The returned passphrase SHOULD be in UTF-8 encoded,
   if not then the library will attempt to encode. */

static void
silc_ask_passphrase(SilcClient client, SilcClientConnection conn,
		    SilcAskPassphrase completion, void *context)
{
  /* MyBot does not support asking passphrases from users since there
     is no user in our little client.  We just reply with nothing. */
  completion(NULL, 0, context);
}


/* Asks whether the user would like to perform the key agreement protocol.
   This is called after we have received an key agreement packet or an
   reply to our key agreement packet. This returns TRUE if the user wants
   the library to perform the key agreement protocol and FALSE if it is not
   desired (application may start it later by calling the function
   silc_client_perform_key_agreement). If TRUE is returned also the
   `completion' and `context' arguments must be set by the application. */

static void
silc_key_agreement(SilcClient client, SilcClientConnection conn,
		   SilcClientEntry client_entry, const char *hostname,
		   SilcUInt16 protocol, SilcUInt16 port)
{
  /* MyBot does not support incoming key agreement protocols, it's too
     simple for that. */
}


/* Notifies application that file transfer protocol session is being
   requested by the remote client indicated by the `client_entry' from
   the `hostname' and `port'. The `session_id' is the file transfer
   session and it can be used to either accept or reject the file
   transfer request, by calling the silc_client_file_receive or
   silc_client_file_close, respectively. */

static void
silc_ftp(SilcClient client, SilcClientConnection conn,
	 SilcClientEntry client_entry, SilcUInt32 session_id,
	 const char *hostname, SilcUInt16 port)
{
  /* MyBot does not support file transfer, it's too simple for that too. */
}


/* Our client operations for the MyBot.  This structure is filled with
   functions and given as argument to the silc_client_alloc function.
   Even though our little bot does not need all these functions we must
   provide them since the SILC Client Library wants them all. */
/* This structure and all the functions were taken from the
   lib/silcclient/client_ops_example.c. */
SilcClientOperations ops = {
  silc_say,
  silc_channel_message,
  silc_private_message,
  silc_notify,
  silc_command,
  silc_command_reply,
  silc_get_auth_method,
  silc_verify_public_key,
  silc_ask_passphrase,
  silc_key_agreement,
  silc_ftp
};

int main(int argc, char **argv)
{
  /* Start mybot */
  return mybot_start();
}