ipop2d.c

广泛使用的邮件服务器！同时

/* ========================================================================
 * Copyright 1988-2008 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 
 * ========================================================================
 */

/*
 * Program:	IPOP2D - IMAP to POP2 conversion server
 *
 * Author:	Mark Crispin
 *		UW Technology
 *		University of Washington
 *		Seattle, WA  98195
 *		Internet: [e-mail]
 *
 * Date:	28 October 1990
 * Last Edited:	13 February 2008
 */


/* Parameter files */

#include <stdio.h>
#include <ctype.h>
#include <errno.h>
extern int errno;		/* just in case */
#include <signal.h>
#include <time.h>
#include "c-client.h"


/* Autologout timer */
#define KODTIMEOUT 60*5
#define LOGINTIMEOUT 60*3
#define TIMEOUT 60*30


/* Size of temporary buffers */
#define TMPLEN 1024


/* Server states */

#define LISN 0
#define AUTH 1
#define MBOX 2
#define ITEM 3
#define NEXT 4
#define DONE 5

/* Global storage */

char *version = "75";		/* edit number of this server */
short state = LISN;		/* server state */
short critical = NIL;		/* non-zero if in critical code */
MAILSTREAM *stream = NIL;	/* mailbox stream */
time_t idletime = 0;		/* time we went idle */
unsigned long nmsgs = 0;	/* number of messages */
unsigned long current = 1;	/* current message number */
unsigned long size = 0;		/* size of current message */
char status[MAILTMPLEN];	/* space for status string */
char *user = "";		/* user name */
char *pass = "";		/* password */
unsigned long *msg = NIL;	/* message translation vector */
char *logout = "Logout";
char *goodbye = "+ Sayonara\015\012";


/* Function prototypes */

int main (int argc,char *argv[]);
void sayonara (int status);
void clkint ();
void kodint ();
void hupint ();
void trmint ();
short c_helo (char *t,int argc,char *argv[]);
short c_fold (char *t);
short c_read (char *t);
short c_retr (char *t);
short c_acks (char *t);
short c_ackd (char *t);
short c_nack (char *t);

/* Main program */

int main (int argc,char *argv[])
{
  char *s,*t;
  char cmdbuf[TMPLEN];
  char *pgmname = (argc && argv[0]) ?
    (((s = strrchr (argv[0],'/')) || (s = strrchr (argv[0],'\\'))) ?
     s+1 : argv[0]) : "ipop2d";
				/* set service name before linkage */
  mail_parameters (NIL,SET_SERVICENAME,(void *) "pop");
#include "linkage.c"
  if (mail_parameters (NIL,GET_DISABLEPLAINTEXT,NIL)) {
    goodbye = "- POP2 server disabled on this system\015\012";
    sayonara (1);
  }
				/* initialize server */
  server_init (pgmname,"pop",NIL,clkint,kodint,hupint,trmint,NIL);
  /* There are reports of POP2 clients which get upset if anything appears
   * between the "+" and the "POP2" in the greeting.
   */
  printf ("+ POP2 %s %s.%s server ready\015\012",tcp_serverhost (),
	  CCLIENTVERSION,version);
  fflush (stdout);		/* dump output buffer */
  state = AUTH;			/* initial server state */
  while (state != DONE) {	/* command processing loop */
    idletime = time (0);	/* get a command under timeout */
    alarm ((state != AUTH) ? TIMEOUT : LOGINTIMEOUT);
    clearerr (stdin);		/* clear stdin errors */
    while (!fgets (cmdbuf,TMPLEN-1,stdin)) {
      if (ferror (stdin) && (errno == EINTR)) clearerr (stdin);
      else {
	char *e = ferror (stdin) ?
	  strerror (errno) : "Unexpected client disconnect";
	alarm (0);		/* disable all interrupts */
	server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
	sprintf (logout = cmdbuf,"%.80s while reading line",e);
	state = DONE;
	stream = mail_close (stream);
	goodbye = NIL;
	sayonara (1);
      }
    }
    alarm (0);			/* make sure timeout disabled */
    idletime = 0;		/* no longer idle */
				/* find end of line */
    if (!strchr (cmdbuf,'\012')) {
      server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
      logout = "- Command line too long\015\012";
      state = DONE;
    }
    else if (!(s = strtok (cmdbuf," \015\012"))) {
      server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
      goodbye = "- Missing or null command\015\012";
      state = DONE;
    }
    else {			/* dispatch based on command */
      ucase (s);		/* canonicalize case */
				/* snarf argument */
      t = strtok (NIL,"\015\012");
      if ((state == AUTH) && !strcmp (s,"HELO")) state = c_helo (t,argc,argv);
      else if ((state == MBOX || state == ITEM) && !strcmp (s,"FOLD"))
 	state = c_fold (t);
      else if ((state == MBOX || state == ITEM) && !strcmp (s,"READ"))
	state = c_read (t);
      else if ((state == ITEM) && !strcmp (s,"RETR")) state = c_retr (t);
      else if ((state == NEXT) && !strcmp (s,"ACKS")) state = c_acks (t);
      else if ((state == NEXT) && !strcmp (s,"ACKD")) state = c_ackd (t);
      else if ((state == NEXT) && !strcmp (s,"NACK")) state = c_nack (t);
      else if ((state == AUTH || state == MBOX || state == ITEM) &&
	       !strcmp (s,"QUIT")) {
	server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
	state = DONE;		/* done in either case */
	if (t) goodbye = "- Bogus argument given to QUIT\015\012";
	else {			/* expunge the stream */
	  if (stream && nmsgs) stream = mail_close_full (stream,CL_EXPUNGE);
	  stream = NIL;		/* don't repeat it */
	}
      }
      else {			/* some other or inappropriate command */
	server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
	goodbye = "- Bogus or out of sequence command\015\012";
	state = DONE;
      }
    }
    fflush (stdout);		/* make sure output blatted */
  }
				/* clean up the stream */
  if (stream) mail_close (stream);
  sayonara (0);
  return 0;			/* stupid compilers */
}


/* Say goodbye
 * Accepts: exit status
 *
 * Does not return
 */

void sayonara (int status)
{
  logouthook_t lgoh = (logouthook_t) mail_parameters (NIL,GET_LOGOUTHOOK,NIL);
  if (goodbye) {		/* have a goodbye message? */
    fputs (goodbye,stdout);
    fflush (stdout);		/* make sure blatted */
  }
  syslog (LOG_INFO,"%s user=%.80s host=%.80s",logout,
	  user ? (char *) user : "???",tcp_clienthost ());
				/* do logout hook if needed */
  if (lgoh) (*lgoh) (mail_parameters (NIL,GET_LOGOUTDATA,NIL));
  _exit (status);		/* all done */
}

/* Clock interrupt
 */

void clkint ()
{
  alarm (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  goodbye = "- Autologout; idle for too long\015\012";
  logout = "Autologout";
  state = DONE;			/* mark state done in either case */
  if (!critical) {		/* badly host if in critical code */
    if (stream && !stream->lock) mail_close (stream);
    stream = NIL;
    sayonara (1);		/* die die die */
  }
}


/* Kiss Of Death interrupt
 */

void kodint ()
{
				/* only if in command wait */
  if (idletime && ((time (0) - idletime) > KODTIMEOUT)) {
    alarm (0);		/* disable all interrupts */
    server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
    goodbye = "- Killed (lost mailbox lock)\015\012";
    logout = "Killed (lost mailbox lock)";
    state = DONE;		/* mark state done in either case */
    if (!critical) {		/* badly host if in critical code */
      if (stream && !stream->lock) mail_close (stream);
      stream = NIL;
      sayonara (1);		/* die die die */
    }
  }
}


/* Hangup interrupt
 */

void hupint ()
{
  alarm (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  goodbye = NIL;
  logout = "Hangup";
  state = DONE;			/* mark state done in either case */
  if (!critical) {		/* badly host if in critical code */
    if (stream && !stream->lock) mail_close (stream);
    stream = NIL;
    sayonara (1);		/* die die die */
  }
}


/* Termination interrupt
 */

void trmint ()
{
  alarm (0);		/* disable all interrupts */
  server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
  goodbye = "- Killed (terminated)\015\012";
  logout = "Killed (terminated)";
  if (critical) state = DONE;	/* mark state done in either case */
  /* Make no attempt at graceful closure since a shutdown may be in
   * progress, and we won't have any time to do mail_close() actions.
   */
  else sayonara (1);		/* die die die */
}

/* Parse HELO command
 * Accepts: pointer to command argument
 * Returns: new state
 */

short c_helo (char *t,int argc,char *argv[])
{
  char *s,*u,*p;
  char tmp[TMPLEN];
  if ((!(t && *t && (u = strtok (t," ")) && (p = strtok (NIL,"\015\012")))) ||
      (strlen (p) >= TMPLEN)) {	/* get user name and password */
    fputs ("- Missing user or password\015\012",stdout);
    return DONE;
  }
				/* copy password, handle quoting */
  for (s = tmp; *p; p++) *s++ = (*p == '\\') ? *++p : *p;
  *s = '\0';			/* tie off string */
  pass = cpystr (tmp);
  if (!(s = strchr (u,':'))) {	/* want remote mailbox? */
				/* no, delimit user from possible admin */
    if (s = strchr (u,'*')) *s++ = '\0';
    if (server_login (user = cpystr (u),pass,s,argc,argv)) {
      syslog (LOG_INFO,"%sLogin user=%.80s host=%.80s",s ? "Admin " : "",
	      user,tcp_clienthost ());
      return c_fold ("INBOX");	/* local; select INBOX */
    }
  }
#ifndef DISABLE_POP_PROXY
				/* can't do if can't log in as anonymous */
  else if (anonymous_login (argc,argv)) {
    *s++ = '\0';		/* separate host name from user name */
    user = cpystr (s);		/* note user name */
    syslog (LOG_INFO,"IMAP login to host=%.80s user=%.80s host=%.80s",u,user,
	    tcp_clienthost ());
				/* initially remote INBOX */
    sprintf (tmp,"{%.128s/user=%.128s}INBOX",u,user);
				/* disable rimap just in case */
    mail_parameters (NIL,SET_RSHTIMEOUT,0);
    return c_fold (tmp);
  }
#endif
  fputs ("- Bad login\015\012",stdout);
  return DONE;
}

/* Parse FOLD command
 * Accepts: pointer to command argument
 * Returns: new state
 */

short c_fold (char *t)
{
  unsigned long i,j,flags;
  char *s = NIL,tmp[2*TMPLEN];
  NETMBX mb;
  if (!(t && *t)) {		/* make sure there's an argument */
    fputs ("- Missing mailbox name\015\012",stdout);
    return DONE;
  }
  myusername_full (&flags);	/* get user type flags */
				/* expunge old stream */
  if (stream && nmsgs) mail_expunge (stream);
  nmsgs = 0;			/* no more messages */
  if (msg) fs_give ((void **) &msg);
#ifndef DISABLE_POP_PROXY
  if (flags == MU_ANONYMOUS) {	/* don't permit proxy to leave IMAP */
    if (stream) {		/* not first time */
      if (!(stream->mailbox && (s = strchr (stream->mailbox,'}'))))
	fatal ("bad previous mailbox name");
      strncpy (tmp,stream->mailbox,i = (++s - stream->mailbox));
      if (i >= TMPLEN) fatal ("ridiculous network prefix");
      strcpy (tmp+i,t);		/* append mailbox to initial spec */
      t = tmp;
    }
				/* must be net name first time */
    else if (!mail_valid_net_parse (t,&mb)) fatal ("anonymous folder bogon");
  }
#endif