sendmail/aux/mailcompat.c

/*
 * 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) != NULL)
    {
        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 */
}