src/commands/talkd/process.c

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/* process.c Copyright Michael Temari 07/22/1996 All Rights Reserved */

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <time.h>
#include <net/hton.h>
#include <net/gen/socket.h>
#include <net/gen/in.h>
#include <net/gen/netdb.h>

#include "talk.h"
#include "talkd.h"
#include "process.h"
#include "finduser.h"

struct entry {
        struct entry *prev;
        struct talk_request rq;
        time_t expire;
        struct entry *next;
};

_PROTOTYPE(static int announce, (struct talk_request *request, char *rhost));
_PROTOTYPE(static struct talk_request *lookup, (struct talk_request *request, int type));
_PROTOTYPE(static int addreq, (struct talk_request *request));
_PROTOTYPE(static delete_invite, (long id));
_PROTOTYPE(static long nextid, (void));
_PROTOTYPE(static void delete, (struct entry *e));

static struct entry *entry = (struct entry *)NULL;

int processrequest(request, reply)
struct talk_request *request;
struct talk_reply *reply;
{
char *p;
struct talk_request *rq;
struct hostent *hp;

   reply->version = TALK_VERSION;
   reply->type = request->type;
   reply->answer = 0;
   reply->junk = 0;
   reply->id = htonl(0);


   /* check version */
   if(request->version != TALK_VERSION) {
        reply->answer = BADVERSION;
        return(0);
   }

   /* check address family */
   if(ntohs(request->addr.sa_family) != AF_INET) {
        reply->answer = BADADDR;
        return(0);
   }

   /* check control address family */
   if(ntohs(request->ctl_addr.sa_family) != AF_INET) {
        reply->answer = BADCTLADDR;
        return(0);
   }

   /* check local name */
   p = request->luser;
   while(*p)
        if(!isprint(*p)) {
                reply->answer = FAILED;
                return(0);
        } else
                p++;

   switch(request->type) {
        case ANNOUNCE:
                reply->answer = find_user(request->ruser, request->rtty);
                if(reply->answer != SUCCESS) break;
                hp = gethostbyaddr((char *)&request->ctl_addr.sin_addr, sizeof(ipaddr_t), AF_INET);
                if(hp == (struct hostent *)NULL) {
                        reply->answer = MACHINE_UNKNOWN;
                        break;
                }
                if((rq = lookup(request, 1)) == (struct talk_request *)NULL) {
                        reply->id = addreq(request);
                        reply->answer = announce(request, hp->h_name);
                        break;
                }
                if(ntohl(request->id) > ntohl(rq->id)) {
                        rq->id = nextid();
                        reply->id = rq->id;
                        reply->answer = announce(request, hp->h_name);
                } else {
                        reply->id = rq->id;
                        reply->answer = SUCCESS;
                }
                break;
        case LEAVE_INVITE:
                rq = lookup(request, 1);
                if(rq == (struct talk_request *)NULL)
                        reply->id = addreq(request);
                else {
                        reply->id = rq->id;
                        reply->answer = SUCCESS;
                }
                break;
        case LOOK_UP:
                if((rq = lookup(request, 0)) == (struct talk_request *)NULL)
                        reply->answer = NOT_HERE;
                else {
                        reply->id = rq->id;
                        memcpy((char *)&reply->addr, (char *)&rq->addr, sizeof(reply->addr));
                        reply->answer = SUCCESS;
                }
                break;
        case DELETE:
                reply->answer = delete_invite(request->id);
                break;
        default:
                reply->answer = UNKNOWN_REQUEST;
   }

   return(0);
}

static int announce(request, rhost)
struct talk_request *request;
char *rhost;
{
char tty[5+TTY_SIZE+1];
struct stat st;
FILE *fp;
time_t now;
struct tm *tm;

   sprintf(tty, "/dev/%s", request->rtty);

   if(stat(tty, &st) < 0)
        return(PERMISSION_DENIED);

   if(!(st.st_mode & S_IWGRP))
        return(PERMISSION_DENIED);

   if((fp = fopen(tty, "w")) == (FILE *)NULL)
        return(PERMISSION_DENIED);

   (void) time(&now);

   tm = localtime(&now);

   fprintf(fp, "\007\007\007\rtalkd: Message from talkd@%s at %d:%02d:%02d\r\n",
                myhostname, tm->tm_hour, tm->tm_min, tm->tm_sec);
   fprintf(fp, "talkd: %s@%s would like to talk to you\r\n",
                request->luser, rhost);
   fprintf(fp, "talkd: to answer type:  talk %s@%s\r\n",
                request->luser, rhost);

   fclose(fp);

   return(SUCCESS);
}

static struct talk_request *lookup(request, type)
struct talk_request *request;
int type;
{
time_t now;
struct entry *e;

   (void) time(&now);

   for(e = entry; e != (struct entry *)NULL; e = e->next) {
        if(now > e->expire) {
                delete(e);
                continue;
        }
        if(type == 0) {
                if(!strncmp(request->luser, e->rq.ruser, USER_SIZE) &&
                   !strncmp(request->ruser, e->rq.luser, USER_SIZE) &&
                   e->rq.type == LEAVE_INVITE)
                        return(&e->rq);
        } else {
                if(request->type == e->rq.type &&
                   request->pid == e->rq.pid &&
                   !strncmp(request->luser, e->rq.luser, USER_SIZE) &&
                   !strncmp(request->ruser, e->rq.ruser, USER_SIZE)) {
                        e->expire = now + MAX_LIFE;
                        return(&e->rq);
                }
        }
   }
   return((struct talk_request *)NULL);
}

static int addreq(request)
struct talk_request *request;
{
time_t now;
struct entry *e;

   (void) time(&now);
   request->id = nextid();
   e = (struct entry *) malloc(sizeof(struct entry));
   if(e == (struct entry *)NULL) {
        fprintf(stderr, "talkd: out of memory in insert table\n");
        exit(1);
   }
   e->expire = now + MAX_LIFE;
   memcpy((char *)&e->rq, (char *)request, sizeof(struct talk_request));
   e->next = entry;
   if(e->next != (struct entry *)NULL)
        e->next->prev = e;
   e->prev = (struct entry *)NULL;
   entry = e;
   return(request->id);
}

static int delete_invite(id)
long id;
{
time_t now;
struct entry *e;

   (void) time(&now);

   for(e = entry; e != (struct entry *)NULL; e = e->next) {
        if(now > e->expire) {
                delete(e);
                continue;
        }
        if(e->rq.id == id) {
                delete(e);
                return(SUCCESS);
        }
   }
   return(NOT_HERE);
}

static void delete(e)
struct entry *e;
{
   if(e == (struct entry *)NULL) return;

   if(entry == e)
        entry = e->next;
   else
        if(e->prev != (struct entry *)NULL)
                e->prev->next = e->next;

   if(e->next != (struct entry *)NULL)
        e->next->prev = e->prev;

   free((char *)e);

   return;
}

static long nextid()
{
static long id = 0;

   id++;
   if(id <= 0) id = 1;
   return(htonl(id));
}

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