pop3.c

广泛使用的邮件服务器！同时

    status.uidnext = tstream->uid_last + 1;
    status.uidvalidity = tstream->uid_validity;
				/* pass status to main program */
    mm_status (tstream,mbx,&status);
    if (stream != tstream) mail_close (tstream);
    ret = LONGT;
  }
  return ret;			/* success */
}

/* POP3 mail open
 * Accepts: stream to open
 * Returns: stream on success, NIL on failure
 */

MAILSTREAM *pop3_open (MAILSTREAM *stream)
{
  unsigned long i,j;
  char *s,*t,tmp[MAILTMPLEN],usr[MAILTMPLEN];
  NETMBX mb;
  MESSAGECACHE *elt;
				/* return prototype for OP_PROTOTYPE call */
  if (!stream) return &pop3proto;
  mail_valid_net_parse (stream->mailbox,&mb);
  usr[0] = '\0';		/* initially no user name */
  if (stream->local) fatal ("pop3 recycle stream");
				/* /anonymous not supported */
  if (mb.anoflag || stream->anonymous) {
    mm_log ("Anonymous POP3 login not available",ERROR);
    return NIL;
  }
				/* /readonly not supported either */
  if (mb.readonlyflag || stream->rdonly) {
    mm_log ("Read-only POP3 access not available",ERROR);
    return NIL;
  }
				/* copy other switches */
  if (mb.dbgflag) stream->debug = T;
  if (mb.secflag) stream->secure = T;
  mb.trysslflag = stream->tryssl = (mb.trysslflag || stream->tryssl) ? T : NIL;
  stream->local =		/* instantiate localdata */
    (void *) memset (fs_get (sizeof (POP3LOCAL)),0,sizeof (POP3LOCAL));
  stream->sequence++;		/* bump sequence number */
  stream->perm_deleted = T;	/* deleted is only valid flag */

  if ((LOCAL->netstream =	/* try to open connection */
       net_open (&mb,NIL,pop3_port ? pop3_port : POP3TCPPORT,
		 (NETDRIVER *) mail_parameters (NIL,GET_SSLDRIVER,NIL),
		 "*pop3s",pop3_sslport ? pop3_sslport : POP3SSLPORT)) &&
      pop3_reply (stream)) {
    mm_log (LOCAL->reply,NIL);	/* give greeting */
    if (!pop3_auth (stream,&mb,tmp,usr)) pop3_close (stream,NIL);
    else if (pop3_send (stream,"STAT",NIL)) {
      int silent = stream->silent;
      stream->silent = T;
      sprintf (tmp,"{%.200s:%lu/pop3",
	       (long) mail_parameters (NIL,GET_TRUSTDNS,NIL) ?
	       net_host (LOCAL->netstream) : mb.host,
	       net_port (LOCAL->netstream));
      if (mb.tlsflag) strcat (tmp,"/tls");
      if (mb.tlssslv23) strcat (tmp,"/tls-sslv23");
      if (mb.notlsflag) strcat (tmp,"/notls");
      if (mb.sslflag) strcat (tmp,"/ssl");
      if (mb.novalidate) strcat (tmp,"/novalidate-cert");
      if (LOCAL->loser = mb.loser) strcat (tmp,"/loser");
      if (stream->secure) strcat (tmp,"/secure");
      sprintf (tmp + strlen (tmp),"/user=\"%s\"}%s",usr,mb.mailbox);
      stream->inbox = T;	/* always INBOX */
      fs_give ((void **) &stream->mailbox);
      stream->mailbox = cpystr (tmp);
				/* notify upper level */
      mail_exists (stream,stream->uid_last = strtoul (LOCAL->reply,NIL,10));
      mail_recent (stream,stream->nmsgs);
				/* instantiate elt */
      for (i = 0; i < stream->nmsgs;) {
	elt = mail_elt (stream,++i);
	elt->valid = elt->recent = T;
	elt->private.uid = i;
      }

				/* trust LIST output if new server */
      if (!LOCAL->loser && LOCAL->cap.capa && pop3_send (stream,"LIST",NIL)) {
	while ((s = net_getline (LOCAL->netstream)) && (*s != '.')) {
	  if ((i = strtoul (s,&t,10)) && (i <= stream->nmsgs) &&
	      (j = strtoul (t,NIL,10))) mail_elt (stream,i)->rfc822_size = j;
	  fs_give ((void **) &s);
	}
				/* flush final dot */
	if (s) fs_give ((void **) &s);
	else {			/* lost connection */
	  mm_log ("POP3 connection broken while itemizing messages",ERROR);
	  pop3_close (stream,NIL);
	  return NIL;
	}
      }
      stream->silent = silent;	/* notify main program */
      mail_exists (stream,stream->nmsgs);
				/* notify if empty */
      if (!(stream->nmsgs || stream->silent)) mm_log ("Mailbox is empty",WARN);
    }
    else {			/* error in STAT */
      mm_log (LOCAL->reply,ERROR);
      pop3_close (stream,NIL);	/* too bad */
    }
  }
  else {			/* connection failed */
    if (LOCAL->reply) mm_log (LOCAL->reply,ERROR);
    pop3_close (stream,NIL);	/* failed, clean up */
  }
  return LOCAL ? stream : NIL;	/* if stream is alive, return to caller */
}

/* POP3 capabilities
 * Accepts: stream
 *	    authenticator flags
 * Returns: T on success, NIL on failure
 */

long pop3_capa (MAILSTREAM *stream,long flags)
{
  unsigned long i;
  char *s,*t,*r,*args;
  if (LOCAL->cap.implementation)/* zap all old capabilities */
    fs_give ((void **) &LOCAL->cap.implementation);
  memset (&LOCAL->cap,0,sizeof (LOCAL->cap));
				/* get server capabilities */
  if (pop3_send (stream,"CAPA",NIL)) LOCAL->cap.capa = T;
  else {
    LOCAL->cap.user = T;	/* guess worst-case old server */
    return NIL;			/* no CAPA on this server */
  }
  while ((t = net_getline (LOCAL->netstream)) && (t[1] || (*t != '.'))) {
    if (stream->debug) mm_dlog (t);
				/* get optional capability arguments */
    if (args = strchr (t,' ')) *args++ = '\0';
    if (!compare_cstring (t,"STLS")) LOCAL->cap.stls = T;
    else if (!compare_cstring (t,"PIPELINING")) LOCAL->cap.pipelining = T;
    else if (!compare_cstring (t,"RESP-CODES")) LOCAL->cap.respcodes = T;
    else if (!compare_cstring (t,"TOP")) LOCAL->cap.top = T;
    else if (!compare_cstring (t,"UIDL")) LOCAL->cap.uidl = T;
    else if (!compare_cstring (t,"USER")) LOCAL->cap.user = T;
    else if (!compare_cstring (t,"IMPLEMENTATION") && args)
      LOCAL->cap.implementation = cpystr (args);
    else if (!compare_cstring (t,"EXPIRE") && args) {
      LOCAL->cap.expire = T;	/* note that it is present */
      if (s = strchr(args,' ')){/* separate time from possible USER */
	*s++ = '\0';
				/* in case they add something after USER */
	if ((strlen (s) > 4) && (s[4] == ' ')) s[4] = '\0';
      }
      LOCAL->cap.expire =	/* get expiration time */
	(!compare_cstring (args,"NEVER")) ? 65535 :
	  ((s && !compare_cstring (s,"USER")) ? -atoi (args) : atoi (args));
    }
    else if (!compare_cstring (t,"LOGIN-DELAY") && args) {
      LOCAL->cap.logindelay = T;/* note that it is present */
      if (s = strchr(args,' ')){/* separate time from possible USER */
	*s++ = '\0';
				/* in case they add something after USER */
	if ((strlen (s) > 4) && (s[4] == ' ')) s[4] = '\0';
      }
				/* get delay time */
      LOCAL->cap.delaysecs = (s && !compare_cstring (s,"USER")) ?
	-atoi (args) : atoi (args);
    }
    else if (!compare_cstring (t,"SASL") && args)
      for (args = strtok_r (args," ",&r); args; args = strtok_r (NIL," ",&r))
	if ((i = mail_lookup_auth_name (args,flags)) &&
	    (--i < MAXAUTHENTICATORS))
	  LOCAL->cap.sasl |= (1 << i);
    fs_give ((void **) &t);
  }
  if (t) {			/* flush end of text indicator */
    if (stream->debug) mm_dlog (t);
    fs_give ((void **) &t);
  }
  return LONGT;
}

/* POP3 authenticate
 * Accepts: stream to login
 *	    parsed network mailbox structure
 *	    scratch buffer of length MAILTMPLEN
 *	    place to return user name
 * Returns: T on success, NIL on failure
 */

long pop3_auth (MAILSTREAM *stream,NETMBX *mb,char *pwd,char *usr)
{
  unsigned long i,trial,auths = 0;
  char *t;
  AUTHENTICATOR *at;
  long ret = NIL;
  long flags = (stream->secure ? AU_SECURE : NIL) |
    (mb->authuser[0] ? AU_AUTHUSER : NIL);
  long capaok = pop3_capa (stream,flags);
  NETDRIVER *ssld = (NETDRIVER *) mail_parameters (NIL,GET_SSLDRIVER,NIL);
  sslstart_t stls = (sslstart_t) mail_parameters (NIL,GET_SSLSTART,NIL);
				/* server has TLS? */
  if (stls && LOCAL->cap.stls && !mb->sslflag && !mb->notlsflag &&
      pop3_send (stream,"STLS",NIL)) {
    mb->tlsflag = T;		/* TLS OK, get into TLS at this end */
    LOCAL->netstream->dtb = ssld;
    if (!(LOCAL->netstream->stream =
	  (*stls) (LOCAL->netstream->stream,mb->host,
		   (mb->tlssslv23 ? NIL : NET_TLSCLIENT) |
		   (mb->novalidate ? NET_NOVALIDATECERT : NIL)))) {
				/* drat, drop this connection */
      if (LOCAL->netstream) net_close (LOCAL->netstream);
      LOCAL->netstream= NIL;
      return NIL;		/* TLS negotiation failed */
    }
    pop3_capa (stream,flags);	/* get capabilities now that TLS in effect */
  }
  else if (mb->tlsflag) {	/* user specified /tls but can't do it */
    mm_log ("Unable to negotiate TLS with this server",ERROR);
    return NIL;
  }
  				/* get authenticators from capabilities */
  if (capaok) auths = LOCAL->cap.sasl;
				/* get list of authenticators */
  else if (pop3_send (stream,"AUTH",NIL)) {
    while ((t = net_getline (LOCAL->netstream)) && (t[1] || (*t != '.'))) {
      if (stream->debug) mm_dlog (t);
      if ((i = mail_lookup_auth_name (t,flags)) && (--i < MAXAUTHENTICATORS))
	auths |= (1 << i);
      fs_give ((void **) &t);
    }
    if (t) {			/* flush end of text indicator */
      if (stream->debug) mm_dlog (t);
      fs_give ((void **) &t);
    }
  }
				/* disable LOGIN if PLAIN also advertised */
  if ((i = mail_lookup_auth_name ("PLAIN",NIL)) && (--i < MAXAUTHENTICATORS) &&
      (auths & (1 << i)) &&
      (i = mail_lookup_auth_name ("LOGIN",NIL)) && (--i < MAXAUTHENTICATORS))
    auths &= ~(1 << i);

  if (auths) {			/* got any authenticators? */
    if ((long) mail_parameters (NIL,GET_TRUSTDNS,NIL)) {
				/* remote name for authentication */
      strncpy (mb->host,(long) mail_parameters (NIL,GET_SASLUSESPTRNAME,NIL) ?
	       net_remotehost (LOCAL->netstream) : net_host (LOCAL->netstream),
	       NETMAXHOST-1);
      mb->host[NETMAXHOST-1] = '\0';
    }
    for (t = NIL, LOCAL->saslcancel = NIL; !ret && LOCAL->netstream && auths &&
	 (at = mail_lookup_auth (find_rightmost_bit (&auths)+1)); ) {
      if (t) {			/* previous authenticator failed? */
	sprintf (pwd,"Retrying using %.80s authentication after %.80s",
		 at->name,t);
	mm_log (pwd,NIL);
	fs_give ((void **) &t);
      }
      trial = 0;		/* initial trial count */
      do {
	if (t) {
	  sprintf (pwd,"Retrying %s authentication after %.80s",at->name,t);
	  mm_log (pwd,WARN);
	  fs_give ((void **) &t);
	}
	LOCAL->saslcancel = NIL;
	if (pop3_send (stream,"AUTH",at->name)) {
				/* hide client authentication responses */
	  if (!(at->flags & AU_SECURE)) LOCAL->sensitive = T;
	  if ((*at->client) (pop3_challenge,pop3_response,"pop",mb,stream,
			     &trial,usr) && LOCAL->response) {
	    if (*LOCAL->response == '+') ret = LONGT;
				/* if main program requested cancellation */
	    else if (!trial) mm_log ("POP3 Authentication cancelled",ERROR);
	  }
	  LOCAL->sensitive=NIL;	/* unhide */
	}
				/* remember response if error and no cancel */
	if (!ret && trial) t = cpystr (LOCAL->reply);
      } while (!ret && trial && (trial < pop3_maxlogintrials) &&
	       LOCAL->netstream);
    }
    if (t) {			/* previous authenticator failed? */
      if (!LOCAL->saslcancel) {	/* don't do this if a cancel */
	sprintf (pwd,"Can not authenticate to POP3 server: %.80s",t);
	mm_log (pwd,ERROR);
      }
      fs_give ((void **) &t);
    }
  }

  else if (stream->secure)
    mm_log ("Can't do secure authentication with this server",ERROR);
  else if (mb->authuser[0])
    mm_log ("Can't do /authuser with this server",ERROR);
  else if (!LOCAL->cap.user) mm_log ("Can't login to this server",ERROR);
  else {			/* traditional login */
    trial = 0;			/* initial trial count */
    do {
      pwd[0] = 0;		/* prompt user for password */
      mm_login (mb,usr,pwd,trial++);
      if (pwd[0]) {		/* send login sequence if have password */
	if (pop3_send (stream,"USER",usr)) {
	  LOCAL->sensitive = T;	/* hide this command */
	  if (pop3_send (stream,"PASS",pwd)) ret = LONGT;
	  LOCAL->sensitive=NIL;	/* unhide */
	}
	if (!ret) {		/* failure */
	  mm_log (LOCAL->reply,WARN);
	  if (trial == pop3_maxlogintrials)
	    mm_log ("Too many login failures",ERROR);
	}
      }
				/* user refused to give password */
      else mm_log ("Login aborted",ERROR);
    } while (!ret && pwd[0] && (trial < pop3_maxlogintrials) &&
	     LOCAL->netstream);
  }
  memset (pwd,0,MAILTMPLEN);	/* erase password */
				/* get capabilities if logged in */
  if (ret && capaok) pop3_capa (stream,flags);
  return ret;
}

/* Get challenge to authenticator in binary
 * Accepts: stream
 *	    pointer to returned size
 * Returns: challenge or NIL if not challenge
 */

void *pop3_challenge (void *s,unsigned long *len)
{
  char tmp[MAILTMPLEN];
  void *ret = NIL;
  MAILSTREAM *stream = (MAILSTREAM *) s;
  if (stream && LOCAL->response &&
      (*LOCAL->response == '+') && (LOCAL->response[1] == ' ') &&
      !(ret = rfc822_base64 ((unsigned char *) LOCAL->reply,
			     strlen (LOCAL->reply),len))) {
    sprintf (tmp,"POP3 SERVER BUG (invalid challenge): %.80s",LOCAL->reply);
    mm_log (tmp,ERROR);
  }
  return ret;
}


/* Send authenticator response in BASE64
 * Accepts: MAIL stream
 *	    string to send
 *	    length of string
 * Returns: T if successful, else NIL
 */

long pop3_response (void *s,char *response,unsigned long size)
{
  MAILSTREAM *stream = (MAILSTREAM *) s;
  unsigned long i,j,ret;
  char *t,*u;
  if (response) {		/* make CRLFless BASE64 string */
    if (size) {
      for (t = (char *) rfc822_binary ((void *) response,size,&i),u = t,j = 0;
	   j < i; j++) if (t[j] > ' ') *u++ = t[j];
      *u = '\0';		/* tie off string for mm_dlog() */
      if (stream->debug) mail_dlog (t,LOCAL->sensitive);
				/* append CRLF */
      *u++ = '\015'; *u++ = '\012'; *u = '\0';
      ret = net_sout (LOCAL->netstream,t,u - t);