/* Copyright 1996 by Eric S. Raymond
 * All rights reserved.
 * For license terms, see the file COPYING in this directory.
 */

/***********************************************************************
  module:       driver.c
  project:      popclient
  programmer:   Eric S. Raymond
  description:  Generic driver for mail fetch method protocols

 ***********************************************************************/

#include  <config.h>
#include  <varargs.h>

#include  <stdio.h>
#if defined(STDC_HEADERS)
#include  <string.h>
#endif
#if defined(HAVE_UNISTD_H)
#include  <unistd.h>
#endif

#include  <sys/time.h>
#include  <ctype.h>
#include  <errno.h>
#include  <malloc.h>

#include  "socket.h"
#include  "popclient.h"
#include  "smtp.h"

static struct method *protocol;

#define	SMTP_PORT	25	/* standard SMTP service port */

char tag[TAGLEN];
static int tagnum;
#define GENSYM	(sprintf(tag, "a%04d", ++tagnum), tag)

static int gen_readmsg (int socket, int mboxfd, long len, int delimited,
       char *host, int topipe, int rewrite);

/*********************************************************************
  function:      do_protocol
  description:   retrieve messages from the specified mail server
                 using a given set of methods

  arguments:     
    queryctl     fully-specified options (i.e. parsed, defaults invoked,
                 etc).
    proto        protocol method pointer

  return value:  exit code from the set of PS_.* constants defined in 
                 popclient.h
  calls:
  globals:       reads outlevel.
 *********************************************************************/

int do_protocol(queryctl, proto)
struct hostrec *queryctl;
struct method *proto;
{
    int ok, len;
    int mboxfd;
    char buf [POPBUFSIZE], host[HOSTLEN];
    int socket;
    int first,number,count;

    tagnum = 0;
    protocol = proto;

    /* open the output sink, locking it if it is a folder */
    if (queryctl->output == TO_FOLDER || queryctl->output == TO_STDOUT) {
	if ((mboxfd = openuserfolder(queryctl)) < 0) 
	    return(PS_IOERR);
    } else if (queryctl->output == TO_SMTP) {
	if ((mboxfd = Socket(queryctl->smtphost,SMTP_PORT)) < 0) 
	    return(PS_SOCKET);
    
	/* make it look like mail is coming from the server */
	if (SMTP_helo(mboxfd,queryctl->servername) != SM_OK) {
	    close(mboxfd);
	    mboxfd = 0;
	    return(PS_SMTP);
	}
    }

    /* open a socket to the mail server */
    if ((socket = Socket(queryctl->servername,protocol->port)) < 0) {
	perror("do_protocol: socket");
	ok = PS_SOCKET;
	goto closeUp;
    }

    /* accept greeting message from mail server */
    ok = (protocol->parse_response)(buf, socket);
    if (ok != 0) {
	if (ok != PS_SOCKET)
	    gen_transact(socket, protocol->exit_cmd);
	close(socket);
	goto closeUp;
    }

    /* print the greeting */
    if (outlevel > O_SILENT && outlevel < O_VERBOSE) 
	fprintf(stderr,"%s greeting: %s\n", protocol->name, buf);

    /* try to get authorized to fetch mail */
    ok = (protocol->getauth)(socket, queryctl, buf);
    if (ok == PS_ERROR)
	ok = PS_AUTHFAIL;
    if (ok != 0)
	goto cleanUp;

    /* compute count and first */
    if ((*protocol->getrange)(socket, queryctl, &count, &first) != 0)
	goto cleanUp;

    /* show them how many messages we'll be downloading */
    if (outlevel > O_SILENT && outlevel < O_VERBOSE)
	if (first > 1) 
	    fprintf(stderr,"%d messages in folder, %d new messages.\n", 
		    count, count - first + 1);
	else
	    fprintf(stderr,"%d %smessages in folder.\n", count, ok ? "" : "new ");

    if (count > 0) { 
	for (number = queryctl->flush ? 1 : first;  number<=count; number++) {

	    char *cp;

	    /* open the mail pipe if we're using an MDA */
	    if (queryctl->output == TO_MDA
		&& (queryctl->fetchall || number >= first)) {
		ok = (mboxfd = openmailpipe(queryctl)) < 0 ? -1 : 0;
		if (ok != 0)
		    goto cleanUp;
	    }
           
	    if (queryctl->flush && number < first && !queryctl->fetchall) 
		ok = 0;  /* no command to send here, will delete message below */
	    else
	    {
		(*protocol->fetch)(socket, number, linelimit, &len);
		if (outlevel == O_VERBOSE)
		    if (protocol->delimited)
			fprintf(stderr,"fetching message %d (delimited)\n",number);
		    else
			fprintf(stderr,"fetching message %d (%d bytes)\n",number,len);
		ok = gen_readmsg(socket,mboxfd,len,protocol->delimited,
				 queryctl->servername,
				 queryctl->output, 
				 queryctl->rewrite);
		if (protocol->trail)
		    (*protocol->trail)(socket, queryctl, number);
		if (ok != 0)
		    goto cleanUp;
	    }

	    /* maybe we delete this message now? */
	    if ((number < first && queryctl->flush) || !queryctl->keep) {
		if (outlevel > O_SILENT && outlevel < O_VERBOSE) 
		    fprintf(stderr,"flushing message %d\n", number);
		else
		    ;
		ok = gen_transact(socket, protocol->delete_cmd, number);
		if (ok != 0)
		    goto cleanUp;
	    }

	    /* close the mail pipe, we'll reopen before next message */
	    if (queryctl->output == TO_MDA
		&& (queryctl->fetchall || number >= first)) {
		ok = closemailpipe(mboxfd);
		if (ok != 0)
		    goto cleanUp;
	    }
	}

	/* remove all messages flagged for deletion */
        if (!queryctl->keep && protocol->expunge_cmd)
	{
	    ok = gen_transact(socket, protocol->expunge_cmd);
	    if (ok != 0)
		goto cleanUp;
        }

	ok = gen_transact(socket, protocol->exit_cmd);
	if (ok == 0)
	    ok = PS_SUCCESS;
	close(socket);
	goto closeUp;
    }
    else {
	ok = gen_transact(socket, protocol->exit_cmd);
	if (ok == 0)
	    ok = PS_NOMAIL;
	close(socket);
	goto closeUp;
    }

cleanUp:
    if (ok != 0 && ok != PS_SOCKET)
	gen_transact(socket, protocol->exit_cmd);

closeUp:
    if (queryctl->output == TO_FOLDER)
    {
	if (closeuserfolder(mboxfd) < 0 && ok == 0)
	    ok = PS_IOERR;
    }
    else if (queryctl->output == TO_SMTP && mboxfd  > 0)
	close(mboxfd);

    if (ok == PS_IOERR || ok == PS_SOCKET) 
	perror("do_protocol: cleanUp");

    return(ok);
}

/*********************************************************************
  function:      gen_send
  description:   Assemble command in print style and send to the server

  arguments:     
    socket       socket to which the server is connected.
    fmt          printf-style format

  return value:  none.
  calls:         SockPuts.
  globals:       reads outlevel.
 *********************************************************************/

void gen_send(socket, fmt, va_alist)
int socket;
const char *fmt;
va_dcl {

  char buf [POPBUFSIZE];
  va_list ap;

  if (protocol->tagged)
      (void) sprintf(buf, "%s ", GENSYM);
  else
      buf[0] = '\0';

  va_start(ap);
  vsprintf(buf + strlen(buf), fmt, ap);
  va_end(ap);

  SockPuts(socket, buf);

  if (outlevel == O_VERBOSE)
    fprintf(stderr,"> %s\n", buf);
}

/*********************************************************************
  function:      gen_transact
  description:   Assemble command in print style and send to the server.
                 then accept a protocol-dependent response.

  arguments:     
    socket       socket to which the server is connected.
    fmt          printf-style format

  return value:  none.
  calls:         SockPuts, imap_ok.
  globals:       reads outlevel.
 *********************************************************************/

int gen_transact(socket, fmt, va_alist)
int socket;
const char *fmt;
va_dcl {

  int ok;
  char buf [POPBUFSIZE];
  va_list ap;

  if (protocol->tagged)
      (void) sprintf(buf, "%s ", GENSYM);
  else
      buf[0] = '\0';

  va_start(ap);
  vsprintf(buf + strlen(buf), fmt, ap);
  va_end(ap);

  SockPuts(socket, buf);

  if (outlevel == O_VERBOSE)
    fprintf(stderr,"> %s\n", buf);

  ok = (protocol->parse_response)(buf,socket);
  if (ok != 0 && outlevel > O_SILENT && outlevel < O_VERBOSE)
    fprintf(stderr,"%s\n",buf);

  return(ok);
}

/*********************************************************************
  function:      gen_readmsg
  description:   Read the message content 

 as described in RFC 1225.
  arguments:     
    socket       ... to which the server is connected.
    mboxfd       open file descriptor to which the retrieved message will
                 be written.
    len          length of text 
    pophost      name of the POP host 
    output       output mode

  return value:  zero if success else PS_* return code.
  calls:         SockGets.
  globals:       reads outlevel. 
 *********************************************************************/

int gen_readmsg (socket,mboxfd,len,delimited,pophost,output,rewrite)
int socket;
int mboxfd;
long len;
int delimited;
char *pophost;
int output;
int rewrite;
{ 
    char buf [MSGBUFSIZE]; 
    char *bufp;
    char savec;
    char fromBuf[MSGBUFSIZE];
    int n;
    int needFrom;
    int inheaders;
    int lines,sizeticker;
    time_t now;
    /* This keeps the retrieved message count for display purposes */
    static int msgnum = 0;  

    /* set up for status message if outlevel allows it */
    if (outlevel > O_SILENT && outlevel < O_VERBOSE) {
	fprintf(stderr,"reading message %d",++msgnum);
	/* won't do the '...' if retrieved messages are being sent to stdout */
	if (mboxfd == 1)
	    fputs(".\n",stderr);
    }

    /* read the message content from the server */
    inheaders = 1;
    lines = 0;
    sizeticker = MSGBUFSIZE;
    while (delimited || len > 0) {
	if ((n = SockGets(socket,buf,sizeof(buf))) < 0)
	    return(PS_SOCKET);
	len -= n;
	bufp = buf;
	if (buf[0] == '\r' || buf[0] == '\n')
	    inheaders = 0;
	if (*bufp == '.') {
	    bufp++;
	    if (delimited && *bufp == 0)
		break;  /* end of message */
	}
	strcat(bufp,"\n");
     
	/* Check for Unix 'From' header, and add a bogus one if it's not
	   present -- only if not using an MDA.
	   XXX -- should probably parse real From: header and use its 
	   address field instead of bogus 'POPmail' string. 
	   */
	if (output != TO_MDA && lines == 0) {
	    if (strlen(bufp) >= strlen("From ")) {
		savec = *(bufp + 5);
		*(bufp + 5) = 0;
		needFrom = strcmp(bufp,"From ") != 0;
		*(bufp + 5) = savec;
	    }
	    else
		needFrom = 1;
	    if (needFrom) {
		now = time(NULL);
		sprintf(fromBuf,"From POPmail %s",ctime(&now));
		if (write(mboxfd,fromBuf,strlen(fromBuf)) < 0) {
		    perror("gen_readmsg: write");
		    return(PS_IOERR);
		}
	    }
	}

	/*
	 * Edit some headers so that replies will work properly.
	 */
	if (inheaders && rewrite)
	    reply_hack(bufp, pophost);

	/* write this line to the file */
	if (write(mboxfd,bufp,strlen(bufp)) < 0) {
	    perror("gen_readmsg: write");
	    return(PS_IOERR);
	}

	sizeticker -= strlen(bufp);
	if (sizeticker <= 0) {
	    if (outlevel > O_SILENT && outlevel < O_VERBOSE && mboxfd != 1)
		fputc('.',stderr);
	    sizeticker = MSGBUFSIZE;
	}
	lines++;
    }

    /* write message terminator, if any */
    switch (output)
    {
    case TO_SMTP:
	if (write(mboxfd,".\r\n",3) < 0) {
	    perror("gen_readmsg: write");
	    return(PS_IOERR);
	}
	if (SMTP_ok(mboxfd, NULL) != SM_OK)
	    return(PS_SMTP);
	break;

    case TO_FOLDER:
    case TO_STDOUT:
	/* The server may not write the extra newline required by the Unix
	   mail folder format, so we write one here just in case */
	if (write(mboxfd,"\n",1) < 0) {
	    perror("gen_readmsg: write");
	    return(PS_IOERR);
	}
	break;

    case TO_MDA:
	/* The mail delivery agent may require a terminator.  Write it if
	   it has been defined */
#ifdef BINMAIL_TERM
	if (write(mboxfd,BINMAIL_TERM,strlen(BINMAIL_TERM)) < 0) {
	    perror("gen_readmsg: write");
	    return(PS_IOERR);
	}
#endif /* BINMAIL_TERM */
    }

    /* finish up display output */
    if (outlevel == O_VERBOSE)
	fprintf(stderr,"(%d lines of message content)\n",lines);
    else if (outlevel > O_SILENT && mboxfd != 1) 
	fputs(".\n",stderr);
    else
	;
    return(0);
}