/* This file is part of the Project Athena Zephyr Notification System.
 * It contains the hostmanager client program.
 *
 *      Created by:     David C. Jedlinsky
 *
 *      $Source$
 *      $Author$
 *
 *      Copyright (c) 1987 by the Massachusetts Institute of Technology.
 *      For copying and distribution information, see the file
 *      "mit-copyright.h". 
 */

#include "hm.h"

#ifndef lint
#ifndef SABER
static char rcsid_hm_c[] = "$Header$";
#endif SABER
#endif lint

#include <ctype.h>
#include <signal.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/param.h>
#include <hesiod.h>

int serv_sock, no_server = 1, timeout_type = 0, serv_loop = 0;
struct sockaddr_in cli_sin, serv_sin, from;
struct hostent *hp;
char **serv_list, **cur_serv, **clust_info;
u_short cli_port;
char hostname[MAXHOSTNAMELEN], prim_serv[MAXHOSTNAMELEN], loopback[4];

extern int errno;
extern char *index();

void init_hm(), handle_timeout(), resend_notices();
char *upcase();

main(argc, argv)
char *argv[];
{
    caddr_t packet;
    ZNotice_t notice;
    Code_t ret;

    /* Override server argument? */
    (void)gethostname(hostname, MAXHOSTNAMELEN);
    (void)strcpy(prim_serv, "");
    if (argc > 1) 
      (void)strcpy(prim_serv, argv[1]);
    else
      for (clust_info = hes_resolve(hostname, "CLUSTER");
	   *clust_info; clust_info++)
	if (!strncmp("ZEPHYR", upcase(*clust_info), 6)) {
	      (void)strcpy(prim_serv, index(*clust_info, ' ')+1);
	      break;
	}
    
    init_hm();

    DPR2 ("zephyr server port: %u\n", ntohs(serv_sin.sin_port));
    DPR2 ("zephyr client port: %u\n", ntohs(cli_port));
    
#ifndef DEBUG
    if (fork())
      exit(0);
#endif DEBUG

    /* Main loop */
    for ever {
	  DPR ("Waiting for a packet...");
	  packet = (char *) malloc(Z_MAXPKTLEN);
	  ret = ZReceiveNotice(packet, Z_MAXPKTLEN, &notice, NULL, &from);
	  if ((ret != ZERR_NONE) && (ret != EINTR)){
		Zperr(ret);
		com_err("hm", ret, "receiving notice");
		free(packet);
	  } else if (ret != EINTR) {
		/* Where did it come from? */
		DPR ("Got a packet.\n");
		DPR ("notice:\n");
		DPR2("\tz_kind: %d\n", notice.z_kind);
		DPR2("\tz_port: %u\n", ntohs(notice.z_port));
		DPR2("\tz_class: %s\n", notice.z_class);
		DPR2("\tz_class_inst: %s\n", notice.z_class_inst);
		DPR2("\tz_opcode: %s\n", notice.z_opcode);
		DPR2("\tz_sender: %s\n", notice.z_sender);
		DPR2("\tz_recip: %s\n", notice.z_recipient);
		if ((notice.z_kind == SERVACK) ||
		    (notice.z_kind == SERVNAK) ||
		    (notice.z_kind == HMCTL)) {
		      server_manager(&notice);
		      free(packet);
		} else {
		      if (bcmp(loopback, &from.sin_addr, 4) == 0) {
			    /* Client program... */
			    transmission_tower(&notice, packet);
			    DPR2 ("Pending = %d\n", ZPending());
		      } else {
			    syslog(LOG_INFO, "Unknown notice type: %d",
				   notice.z_kind);
			    free(packet);
		      }
		}
	  }
    }
}

void init_hm()
{
      struct servent *sp;
      Code_t ret;

      openlog("hm", LOG_PID, LOG_LOCAL6);
      (void)ZInitialize();
      (void)ZSetServerState(1);  /* Aargh!!! */
      init_queue();
      if ((serv_list = hes_resolve("zephyr", "sloc")) == (char **)NULL) {
	    syslog(LOG_ERR, "No servers?!?");
	    exit(1);
      }
      cur_serv = serv_list;
      if (!strcmp(prim_serv, ""))
	(void)strcpy(prim_serv, *cur_serv);
      
      loopback[0] = 127;
      loopback[1] = 0;
      loopback[2] = 0;
      loopback[3] = 1;
      
      /* Open client socket, for receiving client and server notices */
      
      sp = getservbyname("zephyr-hm", "udp");
      cli_port = sp->s_port;
      
      if ((ret = ZOpenPort(&cli_port)) != ZERR_NONE) {
	    Zperr(ret);
	    com_err("hm", ret, "opening port");
      }
      cli_sin = ZGetDestAddr();
      cli_sin.sin_port = sp->s_port;
      
      /* Open the server socket */
      
      sp = getservbyname("zephyr-clt", "udp");
      bzero(&serv_sin, sizeof(struct sockaddr_in));
      serv_sin.sin_port = sp->s_port;
      
      if ((serv_sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
	    syslog(LOG_ERR, "Server socket failed.");
	    exit(1);
      }

      /* Set up communications with server */
      /* target is "zephyr-clt" port on server machine */

      serv_sin.sin_family = AF_INET;

      /* who to talk to */
      if ((hp = gethostbyname(prim_serv)) == NULL) {
	    DPR("gethostbyname failed\n");
	    find_next_server();
      } else {
	    DPR2 ("Server = %s\n", prim_serv);
	    bcopy(hp->h_addr, &serv_sin.sin_addr, hp->h_length);
      }

      send_boot_notice();

      (void)signal (SIGALRM, handle_timeout);
}

char *upcase(s)
     register char *s;
{
      char *r = s;

      for (; *s; s++)
	if (islower(*s)) *s = toupper(*s);
      return(r);
}

send_boot_notice()
{
      ZNotice_t notice;
      Code_t ret;

      /* Set up server notice */
      notice.z_kind = ACKED;
      notice.z_port = cli_port;
      notice.z_class = ZEPHYR_CTL_CLASS;
      notice.z_class_inst = ZEPHYR_CTL_HM;
      notice.z_opcode = HM_BOOT;
      notice.z_sender = "sender";
      notice.z_recipient = "recip";
      notice.z_message_len = 0;
      
      /* Notify server that this host is here */
      if ((ret = ZSetDestAddr(&serv_sin)) != ZERR_NONE) {
	    Zperr(ret);
	    com_err("hm", ret, "setting destination");
      }
      if ((ret = ZSendNotice(&notice, 0)) != ZERR_NONE) {
	    Zperr(ret);
	    com_err("hm", ret, "sending startup notice");
      }
      timeout_type = BOOTING;
      (void)alarm(SERV_TIMEOUT);
}

find_next_server()
{
      struct hostent *hp;

      if (++serv_loop > 3) {
	    serv_loop = 0;
	    hp = gethostbyname(prim_serv);
	    DPR2 ("Server = %s\n", prim_serv);
      } else {
	    if (*++cur_serv == NULL)
	      cur_serv = serv_list;
	    hp = gethostbyname(*cur_serv);
	    DPR2 ("Server = %s\n", *cur_serv);
      }
      bcopy(hp->h_addr, &serv_sin.sin_addr, hp->h_length);
}

server_manager(notice)
     ZNotice_t *notice;
{
      DPR ("A notice came in from the server.\n");
      if (bcmp(&serv_sin.sin_addr, &from.sin_addr, 4) != 0) {
	    syslog (LOG_INFO, "Bad notice from port %u.", notice->z_port);
	    /* Sent a notice back saying this hostmanager isn't theirs */
      } else {
	    /* This is our server, handle the notice */
	    switch(notice->z_kind) {
		case HMCTL:
		  hm_control(notice);
		  break;
		case SERVNAK:
		case SERVACK:
		  send_back(notice);
		  break;
		default:
		  syslog (LOG_INFO, "Bad notice kind!?");
		  break;
	    }
      }
}

hm_control(notice)
     ZNotice_t *notice;
{
      Code_t ret;

      DPR("Control message!\n");
      if (!strcmp(notice->z_opcode, SERVER_SHUTDOWN))
	    new_server();
      else if (!strcmp(notice->z_opcode, SERVER_PING)) {
	    if (no_server)
	      (void)alarm(0);
	    notice->z_kind = HMACK;
	    if ((ret = ZSetDestAddr(&serv_sin)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "setting destination");
	    }
	    if ((ret = ZSendRawNotice(notice)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "sending ACK");
	    }
	    if (no_server) {
		  no_server = 0;
		  retransmit_queue(&serv_sin);
	    }
      } else
	syslog (LOG_INFO, "Bad control message.");
}

send_back(notice)
     ZNotice_t *notice;
{
      ZNotice_Kind_t kind;
      struct sockaddr_in repl;
      Code_t ret;

      if (no_server)
	(void)alarm(0);
      if (!strcmp(notice->z_opcode, HM_BOOT)) {
	    /* ignore message, just a nak from boot */
      } else {
	    if (remove_notice_from_queue(notice, &kind,
					 &repl) != ZERR_NONE) {
		  syslog (LOG_INFO, "Hey! This packet isn't in my queue!");
	    } else {
		  /* check if client wants an ACK, and send it */
		  if (kind == ACKED) {
			DPR2 ("Client ACK port: %u\n", ntohs(repl.sin_port));
			if ((ret = ZSetDestAddr(&repl)) != ZERR_NONE) {
			      Zperr(ret);
			      com_err("hm", ret, "setting destination");
			}
			if ((ret = ZSendRawNotice(notice)) != ZERR_NONE) {
			      Zperr(ret);
			      com_err("hm", ret, "sending NAK");
			}
		  }
	    }
      }
      if (no_server) {
	    no_server = 0;
	    retransmit_queue(&serv_sin);
      }
}

transmission_tower(notice, packet)
     ZNotice_t *notice;
     caddr_t packet;
{
      ZNotice_t gack;
      Code_t ret;
      struct sockaddr_in gsin;
      int tleft;

      if (notice->z_kind != UNSAFE) {
	    gack = *notice;
	    gack.z_kind = HMACK;
	    gack.z_message_len = 0;
	    gsin = cli_sin;
	    gsin.sin_port = from.sin_port;
	    if (gack.z_port == 0)
	      gack.z_port = from.sin_port;
	    DPR2 ("Client Port = %u\n", ntohs(gack.z_port));
	    notice->z_port = gack.z_port;
	    if ((ret = ZSetDestAddr(&gsin)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "setting destination");
	    }
	    /* Bounce ACK to library */
	    if ((ret = ZSendRawNotice(&gack)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "sending raw notice");
	    }
      }
      if (!no_server) {
	    DPR2 ("Server Port = %u\n", ntohs(serv_sin.sin_port));
	    if ((ret = ZSetDestAddr(&serv_sin)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "setting destination");
	    }
	    if ((ret = ZSendRawNotice(notice)) != ZERR_NONE) {
		  Zperr(ret);
		  com_err("hm", ret, "while sending raw notice");
	    }
	    if ((tleft = alarm(0)) > 0)
	      (void)alarm(tleft);
	    else {
		  timeout_type = NOTICES;
		  (void)alarm(NOTICE_TIMEOUT);
	    }
      }
      (void)add_notice_to_queue(notice, packet, &gsin);
}

new_server()
{
      ZNotice_t notice;
      Code_t ret;

      no_server = 1;
      syslog (LOG_INFO, "Server went down, finding new server.");
      notice.z_kind = ACKED;
      notice.z_port = cli_port;
      notice.z_class = ZEPHYR_CTL_CLASS;
      notice.z_class_inst = ZEPHYR_CTL_HM;
      notice.z_opcode = HM_FLUSH;
      notice.z_sender = "sender";
      notice.z_recipient = "recip";
      notice.z_message_len = 0;
      if ((ret = ZSetDestAddr(&serv_sin)) != ZERR_NONE) {
	    Zperr(ret);
	    com_err("hm", ret, "setting destination");
      }
      if ((ret = ZSendNotice(&notice, 0)) != ZERR_NONE) {
	    Zperr(ret);
	    com_err("hm", ret, "sending flush notice");
      }
      find_next_server();
      send_boot_notice();
}

void handle_timeout()
{
      switch(timeout_type) {
	  case BOOTING:
	    new_server();
	    break;
	  case NOTICES:
	    DPR ("Notice timeout\n");
	    resend_notices(&serv_sin);
	    break;
	  default:
	    syslog (LOG_ERR, "Unknown timeout type: %d\n", timeout_type);
	    break;
      }
}