/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/time.h>

#include <fcntl.h>

#include "rcv.h"
#include "extern.h"

/*
 * Mail -- a mail program
 *
 * Auxiliary functions.
 */

static char *save2str(char *, char *);

/*
 * Return a pointer to a dynamic copy of the argument.
 */
char *
savestr(char *str)
{
        char *new;
        int size = strlen(str) + 1;

        if ((new = salloc(size)) != NULL)
                bcopy(str, new, size);
        return (new);
}

/*
 * Make a copy of new argument incorporating old one.
 */
static char *
save2str(char *str, char *old)
{
        char *new;
        int newsize = strlen(str) + 1;
        int oldsize = old ? strlen(old) + 1 : 0;

        if ((new = salloc(newsize + oldsize)) != NULL) {
                if (oldsize) {
                        bcopy(old, new, oldsize);
                        new[oldsize - 1] = ' ';
                }
                bcopy(str, new + oldsize, newsize);
        }
        return (new);
}

/*
 * Touch the named message by setting its MTOUCH flag.
 * Touched messages have the effect of not being sent
 * back to the system mailbox on exit.
 */
void
touch(struct message *mp)
{

        mp->m_flag |= MTOUCH;
        if ((mp->m_flag & MREAD) == 0)
                mp->m_flag |= MREAD|MSTATUS;
}

/*
 * Test to see if the passed file name is a directory.
 * Return true if it is.
 */
int
isdir(char name[])
{
        struct stat sbuf;

        if (stat(name, &sbuf) < 0)
                return (0);
        return (S_ISDIR(sbuf.st_mode));
}

/*
 * Count the number of arguments in the given string raw list.
 */
int
argcount(char **argv)
{
        char **ap;

        for (ap = argv; *ap++ != NULL;)
                ;
        return (ap - argv - 1);
}

/*
 * Return the desired header line from the passed message
 * pointer (or NULL if the desired header field is not available).
 */
char *
hfield(const char *field, struct message *mp)
{
        FILE *ibuf;
        char linebuf[LINESIZE];
        int lc;
        char *hfield;
        char *colon, *oldhfield = NULL;

        ibuf = setinput(mp);
        if ((lc = mp->m_lines - 1) < 0)
                return (NULL);
        if (readline(ibuf, linebuf, sizeof(linebuf)) < 0)
                return (NULL);
        while (lc > 0) {
                if ((lc = gethfield(ibuf, linebuf, lc, &colon)) < 0)
                        return (oldhfield);
                if ((hfield = ishfield(linebuf, colon, field)) != NULL)
                        oldhfield = save2str(hfield, oldhfield);
        }
        return (oldhfield);
}

/*
 * Return the next header field found in the given message.
 * Return >= 0 if something found, < 0 elsewise.
 * "colon" is set to point to the colon in the header.
 * Must deal with \ continuations & other such fraud.
 */
int
gethfield(FILE *f, char linebuf[], int rem, char **colon)
{
        char line2[LINESIZE];
        char *cp, *cp2;
        int c;

        for (;;) {
                if (--rem < 0)
                        return (-1);
                if ((c = readline(f, linebuf, LINESIZE)) <= 0)
                        return (-1);
                for (cp = linebuf; isprint((unsigned char)*cp) && *cp != ' ' && *cp != ':';
                    cp++)
                        ;
                if (*cp != ':' || cp == linebuf)
                        continue;
                /*
                 * I guess we got a headline.
                 * Handle wraparounding
                 */
                *colon = cp;
                cp = linebuf + c;
                for (;;) {
                        while (--cp >= linebuf && (*cp == ' ' || *cp == '\t'))
                                ;
                        cp++;
                        if (rem <= 0)
                                break;
                        ungetc(c = getc(f), f);
                        if (c != ' ' && c != '\t')
                                break;
                        if ((c = readline(f, line2, sizeof(line2))) < 0)
                                break;
                        rem--;
                        for (cp2 = line2; *cp2 == ' ' || *cp2 == '\t'; cp2++)
                                ;
                        c -= cp2 - line2;
                        if (cp + c >= linebuf + LINESIZE - 2)
                                break;
                        *cp++ = ' ';
                        bcopy(cp2, cp, c);
                        cp += c;
                }
                *cp = 0;
                return (rem);
        }
        /* NOTREACHED */
}

/*
 * Check whether the passed line is a header line of
 * the desired breed.  Return the field body, or 0.
 */

char*
ishfield(char *linebuf, char *colon, const char *field)
{
        char *cp = colon;

        *cp = 0;
        if (strcasecmp(linebuf, field) != 0) {
                *cp = ':';
                return (0);
        }
        *cp = ':';
        for (cp++; *cp == ' ' || *cp == '\t'; cp++)
                ;
        return (cp);
}

/*
 * Copy a string and lowercase the result.
 * dsize: space left in buffer (including space for NULL)
 */
void
istrncpy(char *dest, const char *src, size_t dsize)
{

        strlcpy(dest, src, dsize);
        for (; *dest; dest++)
                *dest = tolower((unsigned char)*dest);
}

/*
 * The following code deals with input stacking to do source
 * commands.  All but the current file pointer are saved on
 * the stack.
 */

static  int     ssp;                    /* Top of file stack */
struct sstack {
        FILE    *s_file;                /* File we were in. */
        int     s_cond;                 /* Saved state of conditionals */
        int     s_loading;              /* Loading .mailrc, etc. */
};
#define SSTACK_SIZE     64              /* XXX was NOFILE. */
static struct sstack sstack[SSTACK_SIZE];

/*
 * Pushdown current input file and switch to a new one.
 * Set the global flag "sourcing" so that others will realize
 * that they are no longer reading from a tty (in all probability).
 */
int
source(void *arg)
{
        char **arglist = arg;
        FILE *fi;
        char *cp;

        if ((cp = expand(*arglist)) == NULL)
                return (1);
        if ((fi = Fopen(cp, "r")) == NULL) {
                warn("%s", cp);
                return (1);
        }
        if (ssp >= SSTACK_SIZE - 1) {
                printf("Too much \"sourcing\" going on.\n");
                (void)Fclose(fi);
                return (1);
        }
        sstack[ssp].s_file = input;
        sstack[ssp].s_cond = cond;
        sstack[ssp].s_loading = loading;
        ssp++;
        loading = 0;
        cond = CANY;
        input = fi;
        sourcing++;
        return (0);
}

/*
 * Pop the current input back to the previous level.
 * Update the "sourcing" flag as appropriate.
 */
int
unstack(void)
{
        if (ssp <= 0) {
                printf("\"Source\" stack over-pop.\n");
                sourcing = 0;
                return (1);
        }
        (void)Fclose(input);
        if (cond != CANY)
                printf("Unmatched \"if\"\n");
        ssp--;
        cond = sstack[ssp].s_cond;
        loading = sstack[ssp].s_loading;
        input = sstack[ssp].s_file;
        if (ssp == 0)
                sourcing = loading;
        return (0);
}

/*
 * Touch the indicated file.
 * This is nifty for the shell.
 */
void
alter(char *name)
{
        struct timespec ts[2];

        (void)clock_gettime(CLOCK_REALTIME, &ts[0]);
        ts[0].tv_sec++;
        ts[1].tv_sec = 0;
        ts[1].tv_nsec = UTIME_OMIT;
        (void)utimensat(AT_FDCWD, name, ts, 0);
}

/*
 * Get sender's name from this message.  If the message has
 * a bunch of arpanet stuff in it, we may have to skin the name
 * before returning it.
 */
char *
nameof(struct message *mp, int reptype)
{
        char *cp, *cp2;

        cp = skin(name1(mp, reptype));
        if (reptype != 0 || charcount(cp, '!') < 2)
                return (cp);
        cp2 = strrchr(cp, '!');
        cp2--;
        while (cp2 > cp && *cp2 != '!')
                cp2--;
        if (*cp2 == '!')
                return (cp2 + 1);
        return (cp);
}

/*
 * Start of a "comment".
 * Ignore it.
 */
char *
skip_comment(char *cp)
{
        int nesting = 1;

        for (; nesting > 0 && *cp; cp++) {
                switch (*cp) {
                case '\\':
                        if (cp[1])
                                cp++;
                        break;
                case '(':
                        nesting++;
                        break;
                case ')':
                        nesting--;
                        break;
                }
        }
        return (cp);
}

/*
 * Skin an arpa net address according to the RFC 822 interpretation
 * of "host-phrase."
 */
char *
skin(char *name)
{
        char *nbuf, *bufend, *cp, *cp2;
        int c, gotlt, lastsp;

        if (name == NULL)
                return (NULL);
        if (strchr(name, '(') == NULL && strchr(name, '<') == NULL
            && strchr(name, ' ') == NULL)
                return (name);

        /* We assume that length(input) <= length(output) */
        if ((nbuf = malloc(strlen(name) + 1)) == NULL)
                err(1, "Out of memory");
        gotlt = 0;
        lastsp = 0;
        bufend = nbuf;
        for (cp = name, cp2 = bufend; (c = *cp++) != '\0'; ) {
                switch (c) {
                case '(':
                        cp = skip_comment(cp);
                        lastsp = 0;
                        break;

                case '"':
                        /*
                         * Start of a "quoted-string".
                         * Copy it in its entirety.
                         */
                        while ((c = *cp) != '\0') {
                                cp++;
                                if (c == '"')
                                        break;
                                if (c != '\\')
                                        *cp2++ = c;
                                else if ((c = *cp) != '\0') {
                                        *cp2++ = c;
                                        cp++;
                                }
                        }
                        lastsp = 0;
                        break;

                case ' ':
                        if (cp[0] == 'a' && cp[1] == 't' && cp[2] == ' ')
                                cp += 3, *cp2++ = '@';
                        else
                        if (cp[0] == '@' && cp[1] == ' ')
                                cp += 2, *cp2++ = '@';
                        else
                                lastsp = 1;
                        break;

                case '<':
                        cp2 = bufend;
                        gotlt++;
                        lastsp = 0;
                        break;

                case '>':
                        if (gotlt) {
                                gotlt = 0;
                                while ((c = *cp) != '\0' && c != ',') {
                                        cp++;
                                        if (c == '(')
                                                cp = skip_comment(cp);
                                        else if (c == '"')
                                                while ((c = *cp) != '\0') {
                                                        cp++;
                                                        if (c == '"')
                                                                break;
                                                        if (c == '\\' && *cp != '\0')
                                                                cp++;
                                                }
                                }
                                lastsp = 0;
                                break;
                        }
                        /* FALLTHROUGH */

                default:
                        if (lastsp) {
                                lastsp = 0;
                                *cp2++ = ' ';
                        }
                        *cp2++ = c;
                        if (c == ',' && !gotlt &&
                            (*cp == ' ' || *cp == '"' || *cp == '<')) {
                                *cp2++ = ' ';
                                while (*cp == ' ')
                                        cp++;
                                lastsp = 0;
                                bufend = cp2;
                        }
                }
        }
        *cp2 = '\0';

        if ((cp = realloc(nbuf, strlen(nbuf) + 1)) != NULL)
                nbuf = cp;
        return (nbuf);
}

/*
 * Fetch the sender's name from the passed message.
 * Reptype can be
 *      0 -- get sender's name for display purposes
 *      1 -- get sender's name for reply
 *      2 -- get sender's name for Reply
 */
char *
name1(struct message *mp, int reptype)
{
        char namebuf[LINESIZE];
        char linebuf[LINESIZE];
        char *cp, *cp2;
        FILE *ibuf;
        int first = 1;

        if ((cp = hfield("from", mp)) != NULL)
                return (cp);
        if (reptype == 0 && (cp = hfield("sender", mp)) != NULL)
                return (cp);
        ibuf = setinput(mp);
        namebuf[0] = '\0';
        if (readline(ibuf, linebuf, sizeof(linebuf)) < 0)
                return (savestr(namebuf));
newname:
        for (cp = linebuf; *cp != '\0' && *cp != ' '; cp++)
                ;
        for (; *cp == ' ' || *cp == '\t'; cp++)
                ;
        for (cp2 = &namebuf[strlen(namebuf)];
            *cp != '\0' && *cp != ' ' && *cp != '\t' &&
            cp2 < namebuf + sizeof(namebuf) - 1;)
                *cp2++ = *cp++;
        *cp2 = '\0';
        if (readline(ibuf, linebuf, sizeof(linebuf)) < 0)
                return (savestr(namebuf));
        if ((cp = strchr(linebuf, 'F')) == NULL)
                return (savestr(namebuf));
        if (strncmp(cp, "From", 4) != 0)
                return (savestr(namebuf));
        while ((cp = strchr(cp, 'r')) != NULL) {
                if (strncmp(cp, "remote", 6) == 0) {
                        if ((cp = strchr(cp, 'f')) == NULL)
                                break;
                        if (strncmp(cp, "from", 4) != 0)
                                break;
                        if ((cp = strchr(cp, ' ')) == NULL)
                                break;
                        cp++;
                        if (first) {
                                cp2 = namebuf;
                                first = 0;
                        } else
                                cp2 = strrchr(namebuf, '!') + 1;
                        strlcpy(cp2, cp, sizeof(namebuf) - (cp2 - namebuf) - 1);
                        strcat(namebuf, "!");
                        goto newname;
                }
                cp++;
        }
        return (savestr(namebuf));
}

/*
 * Count the occurrences of c in str
 */
int
charcount(char *str, int c)
{
        char *cp;
        int i;

        for (i = 0, cp = str; *cp != '\0'; cp++)
                if (*cp == c)
                        i++;
        return (i);
}

/*
 * See if the given header field is supposed to be ignored.
 */
int
isign(const char *field, struct ignoretab ignore[2])
{
        char realfld[LINESIZE];

        if (ignore == ignoreall)
                return (1);
        /*
         * Lower-case the string, so that "Status" and "status"
         * will hash to the same place.
         */
        istrncpy(realfld, field, sizeof(realfld));
        if (ignore[1].i_count > 0)
                return (!member(realfld, ignore + 1));
        else
                return (member(realfld, ignore));
}

int
member(char *realfield, struct ignoretab *table)
{
        struct ignore *igp;

        for (igp = table->i_head[hash(realfield)]; igp != NULL; igp = igp->i_link)
                if (*igp->i_field == *realfield &&
                    equal(igp->i_field, realfield))
                        return (1);
        return (0);
}