/* Copyright 1993-95 by Carl Harris, Jr. Copyright 1996 by Eric S. Raymond
 * All rights reserved.
 * For license terms, see the file COPYING in this directory.
 */

/***********************************************************************
  module:       popclient.c
  project:      popclient
  programmer:   Carl Harris, ceharris@mal.com
		Extensively hacked and improved by esr.
  description:	main driver module for popclient

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


#include <config.h>

#include <stdio.h>

#if defined(STDC_HEADERS)
#include <stdlib.h>
#include <string.h>
#endif

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

#include <signal.h>
#include <pwd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "popclient.h"

/* release info */
#define         RELEASE_TAG	"3.1"

#ifdef HAVE_PROTOTYPES
/* prototypes for internal functions */
int showoptions (struct hostrec *queryctl);
int parseMDAargs (struct hostrec *queryctl);
int showversioninfo (void);
int dump_options (struct hostrec *queryctl);
int query_host(struct hostrec *queryctl);
#endif

/* controls the detail level of status/progress messages written to stderr */
int outlevel;    	/* see the O_.* constants above */
int yydebug;		/* enable parse debugging */

/* daemon mode control */
int poll_interval;	/* poll interval in seconds */
char *logfile;		/* log file for daemon mode */
int quitmode;		/* if --quit was set */

/* miscellaneous global controls */
char *poprcfile;	/* path name of rc file */
char *idfile;		/* path name of id file */
int linelimit;		/* limit # lines retrieved per site */
int versioninfo;	/* emit only version info */

/* args for the MDA, parsed out in the usual fashion by parseMDAargs() */
char *mda_argv [32];

/*********************************************************************
  function:      main
  description:   main driver routine 
  arguments:     
    argc         argument count as passed by runtime startup code.
    argv         argument strings as passed by runtime startup code.

  return value:  an exit status code for the shell -- see the 
                 PS_.* constants defined above.
  calls:         parsecmdline, setdefaults, openuserfolder, doPOP2.
  globals:       none.
 *********************************************************************/

static void termhook();
static char *lockfile;
static int popstatus;
static struct hostrec *hostp, *hostlist = (struct hostrec *)NULL;

main (argc,argv)
int argc;
char **argv;
{ 
    int mboxfd, st;
    struct hostrec cmd_opts, def_opts;
    int parsestatus;
    char *servername; 
    FILE	*tmpfp;
    pid_t pid;

    if (setdefaults(&def_opts) != 0)
	exit(PS_UNDEFINED);

    if ((parsestatus = parsecmdline(argc,argv,&cmd_opts)) < 0)
	exit(PS_SYNTAX);

    if (versioninfo)
	showversioninfo();

    if (prc_parse_file(poprcfile) != 0)
	exit(PS_SYNTAX);

    if (optind >= argc)
	append_server_names(&argc, argv);

    /* build in-core data list on all hosts */
    while ((servername = getnextserver(argc, argv, &parsestatus)) != (char *)0)
    {
	if (strcmp(servername, "defaults") == 0)
	    continue;

	hostp = (struct hostrec *)xmalloc(sizeof(struct hostrec));

	prc_mergeoptions(servername, &cmd_opts, &def_opts, hostp);
	strcpy(hostp->servername, servername);
	parseMDAargs(hostp);
	hostp->lastid[0] = '\0';

	hostp->next = hostlist;
	hostlist = hostp;
    }

    /* perhaps we just want to check options? */
    if (versioninfo) {
	printf("Taking options from command line and %s\n", poprcfile);
	for (hostp = hostlist; hostp; hostp = hostp->next) {
	    printf("Options for host %s:\n", hostp->servername);
	    dump_params(hostp);
	}
	if (hostlist == NULL)
	    (void) printf("No mailservers set up -- perhaps %s is missing?\n",
			  poprcfile);
	exit(0);
    }
    else if (hostlist == NULL) {
	(void) fputs("popclient: no mailservers have been specified.\n", stderr);
	exit(PS_SYNTAX);
    }

    /* set up to do lock protocol */
    umask(0077);
    if ((lockfile = (char *) malloc( strlen(getenv("HOME")) + strlen("/.lockfetch-") + HOSTLEN)) == NULL) {
	fprintf(stderr,"popclient: cannot allocate memory for .lockfetch, exiting.\n");
	exit(PS_EXCLUDE);
    }
    strcpy(lockfile, getenv("HOME"));
    strcat(lockfile,"/.lockfetch-");
    gethostname(lockfile+strlen(lockfile),HOSTLEN);

    /* perhaps user asked us to remove a lock */
    if (quitmode)
    {
	FILE* fp;

	if ( (fp = fopen(lockfile, "r")) == NULL ) {
	    fprintf(stderr,"popclient: no other popclient is running\n");
	    return(PS_EXCLUDE);
	}
  
	fscanf(fp,"%d",&pid);
	fprintf(stderr,"popclient: killing popclient at PID %d\n",pid);
	if ( kill(pid,SIGTERM) < 0 )
	    fprintf(stderr,"popclient: error killing the process %d.\n",pid);
	else
	    fprintf(stderr,"popclient: popclient at %d is dead.\n", pid);
  
	fclose(fp);
	remove(lockfile);
	exit(0);
    }


    /* beyond here we don't want more than one popclient running per user */
    if ( (tmpfp = fopen(lockfile, "r")) != NULL ) {
	fscanf(tmpfp,"%d",&pid);
	fprintf(stderr,"Another session appears to be running at pid %d.\nIf you are sure that this is incorrect, remove %s file.\n",pid,lockfile);
	fclose(tmpfp);
	return(PS_EXCLUDE);
    }

    /* let's get stored message IDs from previous transactions */
    if ((st = prc_filecheck(idfile)) != 0) {
	return (st);
    } else if ((tmpfp = fopen(idfile, "r")) != (FILE *)NULL) {
	char buf[POPBUFSIZE+1], host[HOSTLEN+1], id[IDLEN+1];

	while (fgets(buf, POPBUFSIZE, tmpfp) != (char *)NULL) {
	    if ((st = sscanf(buf, "%s %s\n", host, id)) == 2) {
		for (hostp = hostlist; hostp; hostp = hostp->next) {
		    if (strcmp(host, hostp->servername) == 0)
			strcpy(hostp->lastid, id);
		}
	    }
	}
	fclose(tmpfp);
    }

    /*
     * Maybe time to go to demon mode...
     */
    if (poll_interval)
	daemonize(logfile, termhook);

    /* if not locked, assert a lock */
    signal(SIGABRT, termhook);
    signal(SIGINT, termhook);
    signal(SIGTERM, termhook);
    signal(SIGALRM, termhook);
    signal(SIGHUP, termhook);
    signal(SIGPIPE, termhook);
    signal(SIGQUIT, termhook);
    if ( (tmpfp = fopen(lockfile,"w")) != NULL ) {
	fprintf(tmpfp,"%d",getpid());
	fclose(tmpfp);
    }

    /*
     * Query all hosts. If there's only one, the error return will
     * reflect the status of that transaction.
     */
    do {
	for (hostp = hostlist; hostp; hostp = hostp->next) {
	    popstatus = query_host(hostp);
	}

	sleep(poll_interval);
    } while
	(poll_interval);

    if (outlevel == O_VERBOSE)
	fprintf(stderr, "normal termination, status %d\n", popstatus);

    termhook(0);
    exit(popstatus);
}

void termhook(int sig)
{
    FILE *tmpfp;
    int idcount = 0;

    if (sig != 0)
	fprintf(stderr, "terminated with signal %d\n", sig);

    for (hostp = hostlist; hostp; hostp = hostp->next) {
	if (hostp->lastid[0])
	    idcount++;
    }

    /* write updated last-seen IDs */
    if (!idcount)
	unlink(idfile);
    else if ((tmpfp = fopen(idfile, "w")) != (FILE *)NULL) {
	for (hostp = hostlist; hostp; hostp = hostp->next) {
	    if (hostp->lastid[0])
		fprintf(tmpfp, "%s %s\n", hostp->servername, hostp->lastid);
	}
	fclose(tmpfp);
    }

    unlink(lockfile);
    exit(popstatus);
}

/*********************************************************************
  function:      showproto
  description:   protocol index to name mapping
  arguments:
    proto        protocol index
  return value:  string name of protocol
  calls:         none.
  globals:       none.
 *********************************************************************/

char *showproto(proto)
int proto;
{
    switch (proto)
    {
    case P_AUTO: return("auto"); break;
    case P_POP2: return("POP2"); break;
    case P_POP3: return("POP3"); break;
    case P_IMAP: return("IMAP"); break;
    case P_APOP: return("APOP"); break;
    case P_RPOP: return("RPOP"); break;
    default: return("unknown?!?"); break;
    }
}

/*
 * Sequence of protocols to try when autoprobing
 */
static const int autoprobe[] = {P_POP3, P_IMAP, P_POP2};

int query_host(queryctl)
/* perform fetch transaction with single host */
struct hostrec *queryctl;
{
    int i, st;

    if (outlevel != O_SILENT)
    {
	time_t now;

	time(&now);
	fprintf(stderr, "popclient: querying %s (protocol %s) at %s",
	    queryctl->servername, showproto(queryctl->protocol), ctime(&now));
    }
    switch (queryctl->protocol) {
    case P_AUTO:
	for (i = 0; i < sizeof(autoprobe)/sizeof(autoprobe[0]); i++)
	{
	    queryctl->protocol = autoprobe[i];
	    if ((st = query_host(queryctl)) == PS_SUCCESS || st == PS_NOMAIL)
		break;
	}
	queryctl->protocol = P_AUTO;
	return(st);
	break;
    case P_POP2:
	return(doPOP2(queryctl));
	break;
    case P_POP3:
    case P_APOP:
	return(doPOP3bis(queryctl));
	break;
    case P_IMAP:
	return(doIMAP(queryctl));
	break;
    default:
	fprintf(stderr,"popclient: unsupported protocol selected.\n");
	return(PS_PROTOCOL);
    }
}
 
/*********************************************************************
  function:      showversioninfo
  description:   display program release and compiler info
  arguments:     none.
  return value:  none.
  calls:         none.
  globals:       none.
 *********************************************************************/

int showversioninfo()
{
    printf("This is popclient release %s\n",RELEASE_TAG);
}

/*********************************************************************
  function:      dump_params
  description:   display program options in English
  arguments:
    queryctl      merged options

  return value:  none.
  calls:         none.
  globals:       linelimit, outlimit.
*********************************************************************/

int dump_params (queryctl)
struct hostrec *queryctl;
{
    char *cp;

    printf("  Username = '%s'\n", queryctl->remotename);
    printf("  Password = '%s'\n", queryctl->password);
    printf("  Protocol is %s\n", showproto(queryctl->protocol));

    printf("  Fetched messages will%s be kept on the server (--keep %s).\n",
	   queryctl->keep ? "" : " not",
	   queryctl->keep ? "on" : "off");
    printf("  %s messages will be retrieved (--all %s).\n",
	   queryctl->fetchall ? "All" : "Only new",
	   queryctl->fetchall ? "on" : "off");
    printf("  Old messages will%s be flushed before message retrieval (--flush %s).\n",
	   queryctl->flush ? "" : " not",
	   queryctl->flush ? "on" : "off");
    printf("  Rewrite of host-local addresses is %sabled (--norewrite %s)\n",
	   queryctl->norewrite ? "dis" : "en",
	   queryctl->norewrite ? "on" : "off");


    switch(queryctl->output)
    {
    case TO_FOLDER:
	printf("  Messages will be appended to '%s'\n", queryctl->userfolder);
	break;
    case TO_MDA:
	printf("  Messages will be delivered with");
	for (cp = queryctl->mda; *cp; cp += strlen(cp) + 1) {
	    printf(" %s", cp);
	}
	putchar('\n');
	break;
    case TO_STDOUT:
	printf("  Messages will be dumped to standard output\n");
    default:
	printf("  Message destination unknown?!?\n");
    }
    if (outlevel == O_VERBOSE)
    {
	if (queryctl->output != TO_FOLDER)
	    printf("  (Mail folder would have been '%s')\n", queryctl->userfolder);
	if (queryctl->output != TO_MDA)
	{
	    printf("  (MDA would have been");
	    for (cp = queryctl->mda; *cp; cp += strlen(cp) + 1) {
		printf(" %s", cp);
	    }
	    printf(")\n");
	}
    }

    if (linelimit == 0)
	printf("  No limit on retrieved message length.\n");
    else
	printf("  Text retrieved per message will be at most %d bytes.\n",
	       linelimit);
    if (queryctl->lastid[0])
	printf("  ID of last message retrieved %s\n", queryctl->lastid);
}

/*********************************************************************
  function:      openuserfolder
  description:   open the file to which the retrieved messages will
                 be appended.  Write-lock the folder if possible.

  arguments:     
    queryctl     fully-determined options (i.e. parsed, defaults invoked,
                 etc).

  return value:  file descriptor for the open file, else -1.
  calls:         none.
  globals:       none.
 *********************************************************************/

int openuserfolder (queryctl)
struct hostrec *queryctl;
{
    int fd;

    if (queryctl->output == TO_STDOUT)
	return(1);
    else    /* queryctl->output == TO_FOLDER */
	if ((fd = open(queryctl->userfolder,O_CREAT|O_WRONLY|O_APPEND,0600)) >= 0) {
#ifdef HAVE_FLOCK
	    if (flock(fd, LOCK_EX) == -1)
	    {
		close(fd);
		fd = -1;
	    }
#endif /* HAVE_FLOCK */
	    return(fd);
	}
	else {
	    perror("popclient: openuserfolder: open()");
	    return(-1);
	}
  
}



/*********************************************************************
  function:      openmailpipe
  description:   open a one-way pipe to the mail delivery agent.
  arguments:     
    queryctl     fully-determined options (i.e. parsed, defaults invoked,
                 etc).

  return value:  open file descriptor for the pipe or -1.
  calls:         none.
  globals:       reads mda_argv.
 *********************************************************************/

int openmailpipe (queryctl)
struct hostrec *queryctl;
{
    int pipefd [2];
    int childpid;
    char binmailargs [80];

    if (pipe(pipefd) < 0) {
	perror("popclient: openmailpipe: pipe");
	return(-1);
    }
    if ((childpid = fork()) < 0) {
	perror("popclient: openmailpipe: fork");
	return(-1);
    }
    else if (childpid == 0) {

	/* in child process space */
	close(pipefd[1]);  /* close the 'write' end of the pipe */
	close(0);          /* get rid of inherited stdin */
	if (dup(pipefd[0]) != 0) {
	    fputs("popclient: openmailpipe: dup() failed\n",stderr);
	    exit(1);
	}

	execv(queryctl->mda, mda_argv+1);

	/* if we got here, an error occurred */
	perror("popclient: openmailpipe: exec");
	return(-1);

    }

    /* in the parent process space */
    close(pipefd[0]);  /* close the 'read' end of the pipe */
    return(pipefd[1]);
}



/*********************************************************************
  function:      closeuserfolder
  description:   close the user-specified mail folder.
  arguments:     
    fd           mail folder descriptor.

  return value:  zero if success else -1.
  calls:         none.
  globals:       none.
 *********************************************************************/

int closeuserfolder(fd)
int fd;
{
    int err;

    if (fd != 1) {   /* not stdout */
	err = close(fd);
    }   
    else
	err = 0;
  
    if (err)
	perror("popclient: closeuserfolder: close");

    return(err);
}



/*********************************************************************
  function:      closemailpipe
  description:   close pipe to the mail delivery agent.
  arguments:     
    queryctl     fully-determined options record
    fd           pipe descriptor.

  return value:  0 if success, else -1.
  calls:         none.
  globals:       none.
 *********************************************************************/

int closemailpipe (fd)
int fd;
{
    int err;
    int childpid;

    if (outlevel == O_VERBOSE)
	fprintf(stderr, "about to close pipe %d\n", fd);

    err = close(fd);
#if defined(STDC_HEADERS)
    childpid = wait(NULL);
#else
    childpid = wait((int *) 0);
#endif
    if (err)
	perror("popclient: closemailpipe: close");

    if (outlevel == O_VERBOSE)
	fprintf(stderr, "closed pipe %d\n", fd);
  
    return(err);
}



/*********************************************************************
  function:      parseMDAargs
  description:   parse the argument string given in agent option into
                 a regular *argv[] array.
  arguments:
    queryctl     fully-determined options record pointer.

  return value:  none.
  calls:         none.
  globals:       writes mda_argv.
 *********************************************************************/

int parseMDAargs (queryctl)
struct hostrec *queryctl;
{
    int argi;
    char *argp;

    /* first put the last segment of the MDA pathname in argv[0] */
    argp = strrchr(queryctl->mda, '/');
    mda_argv[0] = argp ? (argp + 1) : queryctl->mda;
  
    argp = queryctl->mda;
    while (*argp != '\0' && isspace(*argp))	/* skip null first arg */
	argp++;					

    /* now punch nulls into the delimiting whitespace in the args */
    for (argi = 1;  
	 *argp != '\0';
	 argi++) {

	mda_argv[argi] = argp;     /* store pointer to this argument */

	/* find end of this argument */
	while (!(*argp == '\0' || isspace(*argp)))
	    argp++;

	/* punch in a null terminator */
	if (*argp != '\0')
	    *(argp++) = '\0';  
    }
    mda_argv[argi] = (char *) 0;

}

/*********************************************************************
  function:      
  description:   hack message headers so replies will work properly

  arguments:
    after        where to put the hacked header
    before       header to hack
    host         name of the pop header

  return value:  none.
  calls:         none.
  globals:       writes mda_argv.
 *********************************************************************/

void reply_hack(buf, host)
/* hack local mail IDs -- code by Eric S. Raymond 20 Jun 1996 */
char *buf;
const char *host;
{
    const char *from;
    int state = 0;
    char mycopy[POPBUFSIZE];

    if (strncmp("From: ", buf, 6)
	&& strncmp("To: ", buf, 4)
	&& strncmp("Reply-", buf, 6)
	&& strncmp("Cc: ", buf, 4)
	&& strncmp("Bcc: ", buf, 5)) {
	return;
    }

    strcpy(mycopy, buf);
    for (from = mycopy; *from; from++)
    {
	switch (state)
	{
	case 0:   /* before header colon */
	    if (*from == ':')
		state = 1;
	    break;

	case 1:   /* we've seen the colon, we're looking for addresses */
	    if (*from == '"')
		state = 2;
	    else if (*from == '(')
		state = 3;    
	    else if (*from == '<' || isalnum(*from))
		state = 4;
	    break;

	case 2:   /* we're in a quoted human name, copy and ignore */
	    if (*from == '"')
		state = 1;
	    break;

	case 3:   /* we're in a parenthesized human name, copy and ignore */
	    if (*from == ')')
		state = 1;
	    break;

	case 4:   /* the real work gets done here */
	    /*
	     * We're in something that might be an address part,
	     * either a bare unquoted/unparenthesized text or text
	     * enclosed in <> as per RFC822.
	     */
	    /* if the address part contains an @, don't mess with it */
	    if (*from == '@')
		state = 5;

	    /* If the address token is not properly terminated, ignore it. */
	    else if (*from == ' ' || *from == '\t')
		state = 1;

	    /*
	     * On proper termination with no @, insert hostname.
	     * Case '>' catches <>-enclosed mail IDs.  Case ',' catches
	     * comma-separated bare IDs.  Cases \r and \n catch the case
	     * of a single ID alone on the line.
	     */
	    else if (strchr(">,\r\n", *from))
	    {
		strcpy(buf, "@");
		strcat(buf, host);
		buf += strlen(buf);
		state = 1;
	    }

	    /* everything else, including alphanumerics, just passes through */
	    break;

	case 5:   /* we're in a remote mail ID, no need to append hostname */
	    if (*from == '>' || *from == ',' || isspace(*from))
		state = 1;
	    break;
	}

	/* all characters from the old buffer get copied to the new one */
	*buf++ = *from;
    }
    *buf++ = '\0';
}