/*
 *      $Source$
 *      $Author$
 *      $Header$
 *
 *      Copyright (C) 1987, 1988 by the Massachusetts Institute of Technology
 *	For copying and distribution information, please see the file
 *	<mit-copyright.h>.
 *
 *      Server for user registration with Moira and Kerberos.
 *
 *      This file handles the processing of requests for the register
 *      server.
 */

#ifndef lint
static char *rcsid_requests_c = "$Header$";
#endif lint

/*
 * Before you add anything to the list of things that are #included and
 * #defined, make sure that it is not already done in reg_svr.h
 */

#include <mit-copyright.h>
#include <stdio.h>
#include <strings.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/file.h>
#include <krb.h>
#include <des.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include "moira.h"
#include "moira_site.h"
#include "reg_svr.h"

#define NUM_REQUESTS_SAVED 100	/* Number of transactions to save */
#define CUR_REQ (requests[cur_request_index]) /* The current request */
#define NEXT_INDEX(x)  (x == NUM_REQUESTS_SAVED - 1) ? 0 : (x + 1)
#define PREV_INDEX(x)  (x == 0) ? (NUM_REQUESTS_SAVED - 1) : (x - 1)

static struct servent *sp;	/* Service info from /etc/services */
static int s;			/* Socket descriptor */
static struct sockaddr_in sin;	/* Internet style socket address */
static int addrlen;		/* Size of socket address (sin) */

/* In order to elegantly handle multiple retransmissions, an instance
   of this structure will be retained for the last NUM_REQUESTS_SAVED
   transactions with the client. */
struct request_save {
  char out_pkt[BUFSIZ];		/* Buffer for outgoing packet */
  int out_pktlen;		/* Length of outgoing packet */
  U_32BIT seqno;		/* Sequence number for packet transmission */
  u_long ip_address;		/* Internet address of client host */
  u_short cl_port;		/* Port number client used */
};

static struct request_save requests[NUM_REQUESTS_SAVED]; /* Saved packets */
static int cur_request_index = 0;	/* Index to the current request */

void clear_req(struct request_save *req)
{
  req->seqno = 0;
  req->ip_address = 0;
  req->cl_port = 0;
}

void req_initialize(void)
{
  register int i;

  /* Get service information from /etc/services */
  if (!(sp = getservbyname("sms_ureg", "udp")))
    {
      com_err(whoami, errno, " unknown service sms_ureg/udp");
      exit(1);
    }

  /* Get an internet style datagram socket */
  if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0)
    {
      com_err(whoami, errno, " socket");
      exit(1);
    }
  memset(&sin, 0, sizeof(sin));

  sin.sin_family = AF_INET;
  sin.sin_port = sp->s_port;
  sin.sin_addr.s_addr = INADDR_ANY;

  /* Bind a name to the socket */
  if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0)
    {
      com_err(whoami, errno, " bind");
      exit(1);
    }

  for (i = 0; i < NUM_REQUESTS_SAVED; i++)
    clear_req(&(requests[i]));
}

int handle_retransmitted(void)
{
  register int i;		/* A counter */
  int status = FALSE;		/* Return status */

  for (i = PREV_INDEX(cur_request_index); i != cur_request_index;
       i = PREV_INDEX(i))
    {
      if ((requests[i].seqno == CUR_REQ.seqno) &&
	  (requests[i].ip_address == sin.sin_addr.s_addr) &&
	  (requests[i].cl_port == sin.sin_port))
	/* This is a retransmitted packet */
	{
	  status = TRUE;
	  sendto(s, requests[i].out_pkt, requests[i].out_pktlen,
		 0, (struct sockaddr *)&sin, addrlen);
	  break;
	}
    }

  return status;
}

/* This routine takes care of sending packets back to the client and
   caching the necessary information for retransmission detection.
   It is the only place in which cur_request_index should be
   changed. */
void respond(int status, char *text)
{
  CUR_REQ.out_pktlen = sizeof(CUR_REQ.out_pkt);

  if (format_pkt(CUR_REQ.out_pkt, &(CUR_REQ.out_pktlen),
		 CUR_REQ.seqno, status, text))
    com_err(whoami, 0, "Client error message was truncated.");
  sendto(s, CUR_REQ.out_pkt, CUR_REQ.out_pktlen, 0,
	 (struct sockaddr *)&sin, addrlen);

  cur_request_index = NEXT_INDEX(cur_request_index);
}

void get_request(struct msg *message)
{
  static char packet[BUFSIZ];	/* Buffer for incoming packet */
  int pktlen;			/* Length of incoming packet */
  int status = FAILURE;		/* Error status */

  /* Sit around waiting for requests from the client. */
  for (;;)
    {
      com_err(whoami, 0, "*** Ready for next request ***");
      addrlen = sizeof(sin);
      /* Receive a packet */
      if ((pktlen = recvfrom(s, packet, sizeof(packet), 0,
			     (struct sockaddr *)&sin, &addrlen)) < 0)
	{
	  com_err(whoami, errno, " recvfrom");
	  /* Don't worry if error is interrupted system call. */
	  if (errno == EINTR)
	    continue;
	  exit(1);
	}

      /* Store available information */
      CUR_REQ.seqno = 0;
      CUR_REQ.ip_address = sin.sin_addr.s_addr;
      CUR_REQ.cl_port = sin.sin_port;

      /* Parse a request packet and save sequence number */
      if ((status = parse_pkt(packet, pktlen, message)) != SUCCESS)
	{
	  /* If error, format packet to send back to the client */
	  respond(status, NULL);
	}
      else
	{
	  /* Check for retransmitted packet.  handle_retransmitted()
	     returns true if it handled a retransmitted packet. */
	  if (!handle_retransmitted())
	    break;
	}
    }
}

void report(int status, char *message)
{
  respond(status, message);
}

/* This routine prepares a packet to send back to the client.  A
   non-zero return status means that the client error message was
   truncated. */
int format_pkt(char *packet, int *pktlenp, U_32BIT seqno,
	       int cl_status, char *message)
{
  int len;			/* Amount of message to send */
  int status = SUCCESS;		/* Return status */

  /* Convert byte order to network byte order */
  U_32BIT vers = htonl((U_32BIT)CUR_UREG_VERSION);
  cl_status = htonl((U_32BIT)cl_status);
  /* Put current user registration protocol version into the packet */
  memcpy(packet, &vers, sizeof(U_32BIT));
  /* Put sequence number into the packet */
  memcpy(packet + sizeof(U_32BIT), &seqno, sizeof(U_32BIT));
  /* Put error status into the packet */
  memcpy(packet + 2 * sizeof(U_32BIT), &cl_status, sizeof(U_32BIT));

  /* Find out how much of the message to copy; truncate if too short. */
  /* How much room is there left? */
  len = *pktlenp - sizeof(U_32BIT) * 3;
  if (!message)
    message = "";
  if (len < strlen(message) + 1) /* Room for null terminator */
    {
      status = FAILURE;	/* Message was truncated */
      /* Truncate the message */
      message[len - 1] = '\0';
    }

  /* Copy the message into the packet */
  strcpy(packet + 3 * sizeof(U_32BIT), message);
  *pktlenp = 3 * sizeof(U_32BIT) + strlen(message);

  return status;
}

/* The ureg_validate_char variable and routine were taken verbatim
   out of server/qsupport.qc where they are called
   validate_chars.  At some point, it may be desirable
   to put this functionality in one place. */

/* ureg_validate_char: verify that there are no illegal characters in
 * the string.  Legal characters are printing chars other than
 * ", *, ?, \, [ and ].
 */
static int illegalchars[] = {
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* ^@ - ^O */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* ^P - ^_ */
    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, /* SPACE - / */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, /* 0 - ? */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* @ - O */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, /* P - _ */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ` - o */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, /* p - ^? */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
};

int ureg_validate_char(register char *s)
{
  while (*s)
    {
      if (illegalchars[*s++])
	return FAILURE;
    }
  return SUCCESS;
}

/* This routine checks a packet and puts the information in it in
   a structure if it is valid.  It also saves the sequence number
   in the list of saved requests. */
int parse_pkt(char *packet, int pktlen, struct msg *message)
{
  int status = SUCCESS;	/* Error status */

  com_err(whoami, 0, "Packet received");

  if (pktlen < sizeof(U_32BIT))
    status = UREG_BROKEN_PACKET;
  if (status == SUCCESS)
    {
      /* Extract the user registration protocol version from the packet */
      memcpy(&message->version, packet, sizeof(long));
      /* Convert byte order from network to host */
      message->version = ntohl(message->version);
      /* Verify version */
      if (message->version != CUR_UREG_VERSION)
	status = UREG_WRONG_VERSION;
    }

  if (status == SUCCESS)
    {
      packet += sizeof(U_32BIT);
      pktlen -= sizeof(U_32BIT);

      if (pktlen < sizeof(U_32BIT))
	status = UREG_BROKEN_PACKET;
    }

  if (status == SUCCESS)
    {
      /* Extract the sequence number from the packet */
      memcpy(&CUR_REQ.seqno, packet, sizeof(long));

      packet += sizeof(U_32BIT);
      pktlen -= sizeof(U_32BIT);

      if (pktlen < sizeof(U_32BIT))
	status = UREG_BROKEN_PACKET;
    }

  if (status == SUCCESS)
    {
      /* Extract the request from the packet */
      memcpy(&message->request, packet, sizeof(U_32BIT));
      message->request = ntohl(message->request);
      packet += sizeof(U_32BIT);
      pktlen -= sizeof(U_32BIT);

      /* Make sure that the packet contains only valid characters up
	 to the next null */
      if (ureg_validate_char(packet) != SUCCESS)
	{
	  com_err(whoami, 0, "Packet contains invalid characters.");
	  status = UREG_USER_NOT_FOUND;
	}
      else
	{
	  /* Extract first name from the packet */
	  message->first = packet;

	  /* Scan forward until null appears in the packet or there
	     is no more packet! */
	  for (; *packet && pktlen > 0; --pktlen, ++packet)
	    continue;
	  if (pktlen <= 0)
	    status = UREG_BROKEN_PACKET;
	}
    }

  if (status == SUCCESS)
    {
      /* Skip over the null */
      packet++, pktlen--;

      if (ureg_validate_char(packet) != SUCCESS)
	{
	  com_err(whoami, 0, "Packet contains invalid characters.");
	  status = UREG_USER_NOT_FOUND;
	}
      else
	{
	  /* Extract last name from the packet */
	  message->last = packet;

	  for (; *packet && pktlen > 0; --pktlen, ++packet)
	    continue;
	  if (pktlen <= 0)
	    status = UREG_BROKEN_PACKET;
	}
    }

  if (status == SUCCESS)
    {
      packet++, pktlen--;

      if (pktlen <= 0)
	status = UREG_BROKEN_PACKET;
    }

  /* Extract encrypted information from packet */
  message->encrypted = packet;
  message->encrypted_len = pktlen;

  if (status == SUCCESS)
    {
      com_err(whoami, status, "Request %d for %s %s", message->request,
	      message->first, message->last);
    }
  else
    com_err(whoami, status, " - parse packet failed.");

  return status;
}


u_long cur_req_sender(void)
{
  return CUR_REQ.ip_address;
}