/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 *      Copyright (c) 1983, 1984, 1986, 1986, 1987, 1988, 1989 AT&T
 *        All Rights Reserved
 */

/*
 *  Vacation
 *  Copyright (c) 1983  Eric P. Allman
 *  Berkeley, California
 *
 *  Copyright (c) 1983 Regents of the University of California.
 *  All rights reserved.  The Berkeley software License Agreement
 *  specifies the terms and conditions for redistribution.
 */

#include <pwd.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <sysexits.h>
#include <string.h>
#include <ctype.h>
#include <sm/bitops.h>
#include "conf.h"

/*
 *  MAILCOMPAT -- Deliver mail to a user's mailbox with the "From's" stuffed.
 */

typedef int bool;

#define FALSE   0
#define TRUE    1

bool    Debug = FALSE;
char    *myname;                /* person who is to have their mail filtered */
char    *homedir;               /* home directory of said person */
char    *AliasList[MAXLINE];    /* list of aliases to allow */
char    *fromp;
char    *fromuser;
int     AliasCount = 0;

static char *newstr();

int     ask(char *);
int     sendmessage(char *);
void    AutoInstall(void);
void    usrerr(const char *, ...);

int
main(argc, argv)
        int argc;
        char **argv;
{
        register char *p;
        struct passwd *pw;
        extern char *getfrom();

        /* process arguments */
        while (--argc > 0 && (p = *++argv) != NULL && *p == '-')
        {
                switch (*++p)
                {
                    case 'd':   /* debug */
                        Debug = TRUE;
                        break;
                    default:
                        usrerr("Unknown flag -%s", p);
                        exit(EX_USAGE);
                }
        }

        /* verify recipient argument */
        if (argc != 1)
        {
                if (argc == 0)
                        AutoInstall();
                else
                        usrerr("Usage: mailcompat username (or) mailcompat -r");
                exit(EX_USAGE);
        }

        myname = p;
        /* find user's home directory */
        pw = getpwnam(myname);
        if (pw == NULL)
        {
                usrerr("user: %s look up failed, name services outage ?", myname);
                exit(EX_TEMPFAIL);
        }
        homedir = newstr(pw->pw_dir);

        /* read message from standard input (just from line) */
        fromuser = getfrom(&fromp);
        return (sendmessage(fromuser));
}

/*
**  sendmessage -- read message from standard input do the from stuffing
**             and forward to /bin/mail, Being sure to delete any
**             content-length headers (/bin/mail recalculates them).
**
**
**      Parameters:
**              none.
**
**
**      Side Effects:
**              Reads first line from standard input.
*/

#define L_HEADER        "Content-Length:"
#define LL_HEADER       15

int
sendmessage(from)
char *from;
{
        static char line[MAXLINE];
        static char command[MAXLINE];
        bool in_body = FALSE;
        FILE *mail_fp;
        static char user_name[L_cuserid];

        if (from == NULL)
                from = cuserid(user_name);

        snprintf(command, sizeof (command), "/bin/mail -f %s -d %s", from,
            myname);
        mail_fp = popen(command, "w");

        /* read the  line */
        while (fgets(line, sizeof line, stdin) != NULL)
        {
                if (line[0] == (char)'\n')  /* end of mail headers */
                        in_body = TRUE;
                if (in_body && (strncmp(line, "From ", 5) == 0))
                        fprintf(mail_fp, ">");
                if (in_body || (strncasecmp(line, L_HEADER, LL_HEADER) != 0))
                        fputs(line, mail_fp);
        }
        return (pclose(mail_fp));
}

char *
getfrom(shortp)
char **shortp;
{
        static char line[MAXLINE];
        register char *p, *start, *at, *bang;
        char saveat;

        /* read the from line */
        if (fgets(line, sizeof line, stdin) == NULL ||
            strncmp(line, "From ", 5) != 0)
        {
                usrerr("No initial From line");
                exit(EX_USAGE);
        }

        /* find the end of the sender address and terminate it */
        start = &line[5];
        p = strchr(start, ' ');
        if (p == NULL)
        {
                usrerr("Funny From line '%s'", line);
                exit(EX_USAGE);
        }
        *p = '\0';

        /*
         * Strip all but the rightmost UUCP host
         * to prevent loops due to forwarding.
         * Start searching leftward from the leftmost '@'.
         *      a!b!c!d yields a short name of c!d
         *      a!b!c!d@e yields a short name of c!d@e
         *      e@a!b!c yields the same short name
         */
#ifdef VDEBUG
printf("start='%s'\n", start);
#endif /* VDEBUG */
        *shortp = start;                        /* assume whole addr */
        if ((at = strchr(start, '@')) == NULL)  /* leftmost '@' */
                at = p;                         /* if none, use end of addr */
        saveat = *at;
        *at = '\0';
        if ((bang = strrchr(start, '!')) != NULL) {     /* rightmost '!' */
                char *bang2;
                *bang = '\0';
                if ((bang2 = strrchr(start, '!')) != NULL) /* 2nd rightmost '!' */
                        *shortp = bang2 + 1;            /* move past ! */
                *bang = '!';
        }
        *at = saveat;
#ifdef VDEBUG
printf("place='%s'\n", *shortp);
#endif /* VDEBUG */

        /* return the sender address */
        return newstr(start);
}

/*
**  USRERR -- print user error
**
**      Parameters:
**              f -- format.
**
**      Returns:
**              none.
**
**      Side Effects:
**              none.
*/

void
usrerr(const char *f, ...)
{
        va_list alist;

        va_start(alist, f);
        (void) fprintf(stderr, "mailcompat: ");
        (void) vfprintf(stderr, f, alist);
        (void) fprintf(stderr, "\n");
        va_end(alist);
}

/*
**  NEWSTR -- copy a string
**
**      Parameters:
**              s -- the string to copy.
**
**      Returns:
**              A copy of the string.
**
**      Side Effects:
**              none.
*/

char *
newstr(s)
        char *s;
{
        char *p;
        size_t psize = strlen(s) + 1;

        p = malloc(psize);
        if (p == NULL)
        {
                usrerr("newstr: cannot alloc memory");
                exit(EX_OSERR);
        }
        strlcpy(p, s, psize);
        return (p);
}

/*
 * When invoked with no arguments, we fall into an automatic installation
 * mode, stepping the user through a default installation.
 */
void
AutoInstall()
{
        char forward[MAXLINE];
        char line[MAXLINE];
        static char user_name[L_cuserid];
        FILE *f;

        myname = cuserid(user_name);
        homedir = getenv("HOME");
        if (homedir == NULL) {
                usrerr("Home directory unknown");
                exit(EX_CONFIG);
        }

        printf("This program can be used to store your mail in a format\n");
        printf("that you can read with SunOS 4.X based mail readers\n");
        (void) strlcpy(forward, homedir, sizeof (forward));
        (void) strlcat(forward, "/.forward", sizeof (forward));
        f = fopen(forward, "r");
        if (f) {
                printf("You have a .forward file in your home directory");
                printf("  containing:\n");
                while (fgets(line, MAXLINE, f))
                        printf("    %s", line);
                fclose(f);
                if (!ask("Would you like to remove it and disable the mailcompat feature"))
                        exit(0);
                if (unlink(forward))
                        perror("Error removing .forward file:");
                else
                        printf("Back to normal reception of mail.\n");
                exit(0);
        }

        printf("To enable the mailcompat feature a \".forward\" ");
        printf("file is created.\n");
        if (!ask("Would you like to enable the mailcompat feature")) {
                printf("OK, mailcompat feature NOT enabled.\n");
                exit(0);
        }
        f = fopen(forward, "w");
        if (f == NULL) {
                perror("Error opening .forward file");
                exit(EX_USAGE);
        }
        fprintf(f, "\"|/usr/bin/mailcompat %s\"\n", myname);
        fclose(f);
        printf("Mailcompat feature ENABLED.");
        printf("Run mailcompat with no arguments to remove it\n");
}


/*
 * Ask the user a question until we get a reasonable answer
 */
int
ask(prompt)
        char *prompt;
{
        char line[MAXLINE];

        for (;;) {
                printf("%s? ", prompt);
                fflush(stdout);
                fgets(line, sizeof (line), stdin);
                if (line[0] == 'y' || line[0] == 'Y')
                        return (TRUE);
                if (line[0] == 'n' || line[0] == 'N')
                        return (FALSE);
                printf("Please reply \"yes\" or \"no\" (\'y\' or \'n\')\n");
        }
        /* NOTREACHED */
}