Add IDNA support..

[s-mailx.git] / names.c

/*
 * S-nail - a mail user agent derived from Berkeley Mail.
 *
 * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
 * Copyright (c) 2012 Steffen "Daode" Nurpmeso.
 */
/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

/*
 * Mail -- a mail program
 *
 * Handle name lists.
 */

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

#include <errno.h>

#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>

static struct name *    tailof(struct name *name);
static struct name *    extract1(char *line, enum gfield ntype,
                                char *separators, int copypfx);
static char *           yankword(char *ap, char *wbuf, char *separators,
                                int copypfx);
static int              same_name(char *n1, char *n2);
static struct name *    gexpand(struct name *nlist, struct grouphead *gh,
                                int metoo, int ntype);
static struct name *    put(struct name *list, struct name *node);
static struct name *    delname(struct name *np, char *name);

/*
 * Allocate a single element of a name list, initialize its name field to the
 * passed name and return it.
 */
struct name *
nalloc(char *str, enum gfield ntype)
{
        struct addrguts ag;
        struct str in, out;
        struct name *np;

        np = (struct name*)salloc(sizeof *np);
        np->n_flink = NULL;
        np->n_blink = NULL;
        np->n_type = ntype;
        np->n_flags = 0;

        (void)addrspec_with_guts((ntype & (GFULL|GSKIN|GREF)) != 0, str, &ag);
        if ((ag.ag_n_flags & NAME_NAME_SALLOC) == 0) {
                ag.ag_n_flags |= NAME_NAME_SALLOC;
                ag.ag_skinned = savestrbuf(ag.ag_skinned, ag.ag_slen);
        }
        np->n_fullname = np->n_name = ag.ag_skinned;
        np->n_flags = ag.ag_n_flags;

        if (ntype & GFULL) {
                if (ag.ag_ilen == ag.ag_slen
#ifdef USE_IDNA
                                && (ag.ag_n_flags & NAME_IDNA) == 0
#endif
                )
                        goto jleave;
                if (ag.ag_n_flags & NAME_ADDRSPEC_ISFILEORPIPE)
                        goto jleave;
#ifdef USE_IDNA
                if ((ag.ag_n_flags & NAME_IDNA) == 0) {
#endif
                        in.s = str;
                        in.l = ag.ag_ilen;
#ifdef USE_IDNA
                } else {
                        /*
                         * The domain name was IDNA and has been converted.
                         * We also have to ensure that the domain name in
                         * .n_fullname is replaced with the converted version,
                         * since MIME doesn't perform encoding of addresses.
                         */
                        size_t l = ag.ag_iaddr_start,
                                lsuff = ag.ag_ilen - ag.ag_iaddr_end;
                        in.s = ac_alloc(l + ag.ag_slen + lsuff + 1);
                        memcpy(in.s, str, l);
                        memcpy(in.s + l, ag.ag_skinned, ag.ag_slen);
                        l += ag.ag_slen;
                        memcpy(in.s + l, str + ag.ag_iaddr_end, lsuff);
                        l += lsuff;
                        in.s[l] = '\0';
                        in.l = l;
                }
#endif
                mime_fromhdr(&in, &out, TD_ISPR|TD_ICONV);
                np->n_fullname = savestr(out.s);
                free(out.s);
#ifdef USE_IDNA
                if (ag.ag_n_flags & NAME_IDNA)
                        ac_free(in.s);
#endif
                np->n_flags |= NAME_FULLNAME_SALLOC;
        } else if (ntype & GREF) { /* TODO LEGACY */
                /* TODO Unfortunately we had to skin GREFerences i.e. the
                 * TODO surrounding angle brackets have been stripped away.
                 * TODO Necessarily since otherwise the plain address check
                 * TODO fails due to them; insert them back so that valid
                 * TODO headers will be created */
                np->n_fullname = np->n_name = str = salloc(ag.ag_slen + 2 + 1);
                *(str++) = '<';
                memcpy(str, ag.ag_skinned, ag.ag_slen);
                str += ag.ag_slen;
                *(str++) = '>';
                *str = '\0';
        }
jleave:
        return (np);
}

struct name *
ndup(struct name *np, enum gfield ntype)
{
        struct name *nnp;

        if ((ntype & (GFULL|GSKIN)) && (np->n_flags & NAME_SKINNED) == 0) {
                nnp = nalloc(np->n_name, ntype);
                goto jleave;
        }

        nnp = (struct name*)salloc(sizeof *np);
        nnp->n_flink = nnp->n_blink = NULL;
        nnp->n_type = ntype;
        nnp->n_flags = (np->n_flags &
                        ~(NAME_NAME_SALLOC | NAME_FULLNAME_SALLOC)) |
                NAME_NAME_SALLOC;
        nnp->n_name = savestr(np->n_name);
        if (np->n_name == np->n_fullname || (ntype & (GFULL|GSKIN)) == 0)
                nnp->n_fullname = nnp->n_name;
        else {
                nnp->n_flags |= NAME_FULLNAME_SALLOC;
                nnp->n_fullname = savestr(np->n_fullname);
        }
jleave:
        return (nnp);
}

/*
 * Find the tail of a list and return it.
 */
static struct name *
tailof(struct name *name)
{
        struct name *np;

        np = name;
        if (np == NULL)
                return(NULL);
        while (np->n_flink != NULL)
                np = np->n_flink;
        return(np);
}

/*
 * Extract a list of names from a line,
 * and make a list of names from it.
 * Return the list or NULL if none found.
 */
struct name *
extract(char *line, enum gfield ntype)
{
        return extract1(line, ntype, " \t,(", 0);
}

struct name *
sextract(char *line, enum gfield ntype)
{
        if (line && strpbrk(line, ",\"\\(<"))
                return extract1(line, ntype, ",", 1);
        else
                return extract(line, ntype);
}

struct name *
lextract(char *line, enum gfield ntype)
{
        return (extract1(line, ntype, ",", 1));
}

static struct name *
extract1(char *line, enum gfield ntype, char *separators, int copypfx)
{
        char *cp, *nbuf;
        struct name *top, *np, *t;

        if (line == NULL || *line == '\0')
                return NULL;
        top = NULL;
        np = NULL;
        cp = line;
        nbuf = ac_alloc(strlen(line) + 1);
        while ((cp = yankword(cp, nbuf, separators, copypfx)) != NULL) {
                t = nalloc(nbuf, ntype);
                if (top == NULL)
                        top = t;
                else
                        np->n_flink = t;
                t->n_blink = np;
                np = t;
        }
        ac_free(nbuf);
        return top;
}

/*
 * Turn a list of names into a string of the same names.
 */
char *
detract(struct name *np, enum gfield ntype)
{
        int s;
        char *cp, *top;
        struct name *p;
        int comma;

        comma = ntype & GCOMMA;
        if (np == NULL)
                return(NULL);
        ntype &= ~GCOMMA;
        s = 0;
        if ((debug || value("debug")) && comma)
                fprintf(stderr, catgets(catd, CATSET, 145,
                                "detract asked to insert commas\n"));
        for (p = np; p != NULL; p = p->n_flink) {
                if (ntype && (p->n_type & GMASK) != ntype)
                        continue;
                s += strlen(p->n_fullname) + 1;
                if (comma)
                        s++;
        }
        if (s == 0)
                return(NULL);
        s += 2;
        top = salloc(s);
        cp = top;
        for (p = np; p != NULL; p = p->n_flink) {
                if (ntype && (p->n_type & GMASK) != ntype)
                        continue;
                cp = sstpcpy(cp, p->n_fullname);
                if (comma && p->n_flink != NULL)
                        *cp++ = ',';
                *cp++ = ' ';
        }
        *--cp = 0;
        if (comma && *--cp == ',')
                *cp = 0;
        return(top);
}

/*
 * Grab a single word (liberal word)
 * Throw away things between ()'s, and take anything between <>.
 * Strip trailing whitespace as *ap* may come directly from user.
 */
static char *
yankword(char *ap, char *wbuf, char *separators, int copypfx)
{
        char *cp, *pp, *wp;

        cp = ap;
        wp = wbuf;
        while (blankspacechar(*cp) || *cp == ',')
                ++cp;
        pp = cp;
        if ((cp = (char*)nexttoken((char*)cp)) == NULL)
                return NULL;
        if (copypfx)
                while (pp < cp)
                        *wp++ = *pp++;
        if (*cp ==  '<')
                while (*cp && (*wp++ = *cp++) != '>');
        else {
                int incomm = 0;

                while (*cp && (incomm || !strchr(separators, *cp))) {
                        if (*cp == '\"') {
                                if (cp == ap || *(cp - 1) != '\\') {
                                        if (incomm)
                                                incomm--;
                                        else
                                                incomm++;
                                        *wp++ = '\"';
                                } else if (cp != ap) {
                                        *(wp - 1) = '\"';
                                }
                                cp++;
                                continue;
                        }
                        *wp++ = *cp++;
                }
        }
        while (wp > wbuf && blankspacechar(wp[-1]))
                --wp;
        *wp = '\0';
        return cp;
}

/*
 * Check all addresses in np and delete invalid ones.
 */
struct name *
checkaddrs(struct name *np)
{
        struct name *n;

        for (n = np; n != NULL;) {
                if (is_addr_invalid(n, 1)) {
                        if (n->n_blink)
                                n->n_blink->n_flink = n->n_flink;
                        if (n->n_flink)
                                n->n_flink->n_blink = n->n_blink;
                        if (n == np)
                                np = n->n_flink;
                }
                n = n->n_flink;
        }
        return (np);
}

/*
 * For each recipient in the passed name list with a /
 * in the name, append the message to the end of the named file
 * and remove him from the recipient list.
 *
 * Recipients whose name begins with | are piped through the given
 * program and removed.
 */
struct name *
outof(struct name *names, FILE *fo, struct header *hp)
{
        int pipecnt, xcnt, *fda, i;
        char *shell, *date;
        struct name *np;
        time_t now;
        FILE *fin = NULL, *fout;
        (void)hp;

        /*
         * Look through all recipients and do a quick return if no file or pipe
         * addressee is found.
         */
        fda = NULL; /* Silence cc */
        for (pipecnt = xcnt = 0, np = names; np != NULL; np = np->n_flink)
                switch (np->n_flags & NAME_ADDRSPEC_ISFILEORPIPE) {
                case NAME_ADDRSPEC_ISFILE:
                        ++xcnt;
                        break;
                case NAME_ADDRSPEC_ISPIPE:
                        ++pipecnt;
                        break;
                }
        if (pipecnt == 0 && xcnt == 0)
                goto jleave;

        /*
         * Otherwise create an array of file descriptors for each found pipe
         * addressee to get around the dup(2)-shared-file-offset problem, i.e.,
         * each pipe subprocess needs its very own file descriptor, and we need
         * to deal with that.
         * To make our life a bit easier let's just use the auto-reclaimed
         * string storage.
         */
        if (pipecnt == 0) {
                fda = NULL;
                shell = NULL;
        } else {
                fda = (int*)salloc(sizeof(int) * pipecnt);
                for (i = 0; i < pipecnt; ++i)
                        fda[i] = -1;
                if ((shell = value("SHELL")) == NULL)
                        shell = SHELL;
        }

        time(&now);
        date = ctime(&now);

        for (np = names; np != NULL;) {
                if ((np->n_flags & (NAME_ADDRSPEC_ISFILE|NAME_ADDRSPEC_ISPIPE))
                                == 0) {
                        np = np->n_flink;
                        continue;
                }

                /*
                 * See if we have copied the complete message out yet.
                 * If not, do so.
                 */
                if (image < 0) {
                        int c;
                        char *tempEdit;

                        if ((fout = Ftemp(&tempEdit, "Re", "w", 0600, 1))
                                        == NULL) {
                                perror(tr(146, "Creation of temporary image"));
                                ++senderr;
                                goto jcant;
                        }
                        image = open(tempEdit, O_RDWR);
                        if (image >= 0)
                                for (i = 0; i < pipecnt; ++i) {
                                        int fd = open(tempEdit, O_RDONLY);
                                        if (fd < 0) {
                                                (void)close(image);
                                                image = -1;
                                                pipecnt = i;
                                                break;
                                        }
                                        fda[i] = fd;
                                        (void)fcntl(fd, F_SETFD, FD_CLOEXEC);
                                }
                        unlink(tempEdit);
                        Ftfree(&tempEdit);
                        if (image < 0) {
                                perror(tr(147, "Creating descriptor duplicate "
                                        "of temporary image"));
                                ++senderr;
                                Fclose(fout);
                                goto jcant;
                        }
                        fcntl(image, F_SETFD, FD_CLOEXEC);

                        fprintf(fout, "From %s %s", myname, date);
                        c = EOF;
                        while (i = c, (c = getc(fo)) != EOF)
                                putc(c, fout);
                        rewind(fo);
                        if (i != '\n')
                                putc('\n', fout);
                        putc('\n', fout);
                        fflush(fout);
                        if (ferror(fout)) {
                                perror(tr(148, "Finalizing write of temporary "
                                        "image"));
                                Fclose(fout);
                                goto jcantfout;
                        }
                        Fclose(fout);

                        /* If we have to serve file addressees, open reader */
                        if (xcnt != 0 && (fin = Fdopen(image, "r")) == NULL) {
                                perror(tr(149, "Failed to open a duplicate of "
                                        "the temporary image"));
jcantfout:                      ++senderr;
                                (void)close(image);
                                image = -1;
                                goto jcant;
                        }

                        /* From now on use xcnt as a counter for pipecnt */
                        xcnt = 0;
                }

                /*
                 * Now either copy "image" to the desired file
                 * or give it as the standard input to the desired
                 * program as appropriate.
                 */

                if (np->n_flags & NAME_ADDRSPEC_ISPIPE) {
                        int pid;
                        sigset_t nset;

                        sigemptyset(&nset);
                        sigaddset(&nset, SIGHUP);
                        sigaddset(&nset, SIGINT);
                        sigaddset(&nset, SIGQUIT);
                        pid = start_command(shell, &nset,
                                fda[xcnt++], -1, "-c", np->n_name + 1, NULL);
                        if (pid < 0) {
                                fprintf(stderr, tr(281,
                                        "Message piping to <%s> failed\n"),
                                        np->n_name);
                                ++senderr;
                                goto jcant;
                        }
                        free_child(pid);
                } else {
                        char *fname = file_expand(np->n_name);
                        if (fname == NULL) {
                                fprintf(stderr, tr(81,
                                        "\"%s\": Expansion failed.\n"),
                                        np->n_name);
                                ++senderr;
                                goto jcant;
                        }
                        if ((fout = Zopen(fname, "a", NULL)) == NULL) {
                                fprintf(stderr, tr(282,
                                        "Message writing to <%s> failed: %s\n"),
                                        fname, strerror(errno));
                                ++senderr;
                                goto jcant;
                        }
                        rewind(fin);
                        while ((i = getc(fin)) != EOF)
                                putc(i, fout);
                        if (ferror(fout)) {
                                fprintf(stderr, tr(282,
                                        "Message writing to <%s> failed: %s\n"),
                                        fname, tr(283, "write error"));
                                ++senderr;
                        }
                        Fclose(fout);
                }
jcant:
                /*
                 * In days of old we removed the entry from the
                 * the list; now for sake of header expansion
                 * we leave it in and mark it as deleted.
                 */
                np->n_type |= GDEL;
                np = np->n_flink;
                if (image < 0)
                        goto jdelall;
        }
jleave:
        if (fin != NULL)
                Fclose(fin);
        for (i = 0; i < pipecnt; ++i)
                (void)close(fda[i]);
        if (image >= 0) {
                close(image);
                image = -1;
        }
        return (names);

jdelall:
        while (np != NULL) {
                if ((np->n_flags & (NAME_ADDRSPEC_ISFILE|NAME_ADDRSPEC_ISPIPE))
                                != 0)
                        np->n_type |= GDEL;
                np = np->n_flink;
        }
        goto jleave;
}

static int
same_name(char *n1, char *n2)
{
        int c1, c2;

        if (value("allnet") != NULL) {
                do {
                        c1 = (*n1++ & 0377);
                        c2 = (*n2++ & 0377);
                        c1 = lowerconv(c1);
                        c2 = lowerconv(c2);
                        if (c1 != c2)
                                return 0;
                } while (c1 != '\0' && c2 != '\0' && c1 != '@' && c2 != '@');
                return 1;
        } else
                return asccasecmp(n1, n2) == 0;
}

/*
 * Map all of the aliased users in the invoker's mailrc
 * file and insert them into the list.
 * Changed after all these months of service to recursively
 * expand names (2/14/80).
 */

struct name *
usermap(struct name *names)
{
        struct name *new, *np, *cp;
        struct grouphead *gh;
        int metoo;

        new = NULL;
        np = names;
        metoo = (value("metoo") != NULL);
        while (np != NULL) {
                if (np->n_name[0] == '\\') {
                        cp = np->n_flink;
                        new = put(new, np);
                        np = cp;
                        continue;
                }
                gh = findgroup(np->n_name);
                cp = np->n_flink;
                if (gh != NULL)
                        new = gexpand(new, gh, metoo, np->n_type);
                else
                        new = put(new, np);
                np = cp;
        }
        return(new);
}

/*
 * Recursively expand a group name.  We limit the expansion to some
 * fixed level to keep things from going haywire.
 * Direct recursion is not expanded for convenience.
 */

static struct name *
gexpand(struct name *nlist, struct grouphead *gh, int metoo, int ntype)
{
        struct group *gp;
        struct grouphead *ngh;
        struct name *np;
        static int depth;
        char *cp;

        if (depth > MAXEXP) {
                printf(catgets(catd, CATSET, 150,
                        "Expanding alias to depth larger than %d\n"), MAXEXP);
                return(nlist);
        }
        depth++;
        for (gp = gh->g_list; gp != NULL; gp = gp->ge_link) {
                cp = gp->ge_name;
                if (*cp == '\\')
                        goto quote;
                if (strcmp(cp, gh->g_name) == 0)
                        goto quote;
                if ((ngh = findgroup(cp)) != NULL) {
                        nlist = gexpand(nlist, ngh, metoo, ntype);
                        continue;
                }
quote:
                np = nalloc(cp, ntype|GFULL);
                /*
                 * At this point should allow to expand
                 * to self if only person in group
                 */
                if (gp == gh->g_list && gp->ge_link == NULL)
                        goto skip;
                if (!metoo && same_name(cp, myname))
                        np->n_type |= GDEL;
skip:
                nlist = put(nlist, np);
        }
        depth--;
        return(nlist);
}

/*
 * Concatenate the two passed name lists, return the result.
 */
struct name *
cat(struct name *n1, struct name *n2)
{
        struct name *tail;

        if (n1 == NULL)
                return(n2);
        if (n2 == NULL)
                return(n1);
        tail = tailof(n1);
        tail->n_flink = n2;
        n2->n_blink = tail;
        return(n1);
}

/*
 * Unpack the name list onto a vector of strings.
 * Return an error if the name list won't fit.
 */
char **
unpack(struct name *np)
{
        char **ap, **top;
        struct name *n;
        int t, extra, metoo, verbose;

        n = np;
        if ((t = count(n)) == 0)
                panic(catgets(catd, CATSET, 151, "No names to unpack"));
        /*
         * Compute the number of extra arguments we will need.
         * We need at least two extra -- one for "mail" and one for
         * the terminating 0 pointer.  Additional spots may be needed
         * to pass along -f to the host mailer.
         */
        extra = 2;
        extra++;
        metoo = value("metoo") != NULL;
        if (metoo)
                extra++;
        verbose = value("verbose") != NULL;
        if (verbose)
                extra++;
        /*LINTED*/
        top = (char **)salloc((t + extra) * sizeof *top);
        ap = top;
        *ap++ = "send-mail";
        *ap++ = "-i";
        if (metoo)
                *ap++ = "-m";
        if (verbose)
                *ap++ = "-v";
        for (; n != NULL; n = n->n_flink)
                if ((n->n_type & GDEL) == 0)
                        *ap++ = n->n_name;
        *ap = NULL;
        return(top);
}

/*
 * Remove all of the duplicates from the passed name list by
 * insertion sorting them, then checking for dups.
 * Return the head of the new list.
 */
struct name *
elide(struct name *names)
{
        struct name *np, *t, *newn, *x;

        if (names == NULL)
                return (NULL);
        /* Throw away all deleted nodes (XXX merge with plain sort below?) */
        for (newn = np = NULL; names != NULL; names = names->n_flink)
                if  ((names->n_type & GDEL) == 0) {
                        names->n_blink = np;
                        if (np)
                                np->n_flink = names;
                        else
                                newn = names;
                        np = names;
                }
        if (newn == NULL)
                return (NULL);

        np = newn->n_flink;
        if (np != NULL)
                np->n_blink = NULL;
        newn->n_flink = NULL;

        while (np != NULL) {
                t = newn;
                while (asccasecmp(t->n_name, np->n_name) < 0) {
                        if (t->n_flink == NULL)
                                break;
                        t = t->n_flink;
                }

                /*
                 * If we ran out of t's, put the new entry after
                 * the current value of t.
                 */

                if (asccasecmp(t->n_name, np->n_name) < 0) {
                        t->n_flink = np;
                        np->n_blink = t;
                        t = np;
                        np = np->n_flink;
                        t->n_flink = NULL;
                        continue;
                }

                /*
                 * Otherwise, put the new entry in front of the
                 * current t.  If at the front of the list,
                 * the new guy becomes the new head of the list.
                 */

                if (t == newn) {
                        t = np;
                        np = np->n_flink;
                        t->n_flink = newn;
                        newn->n_blink = t;
                        t->n_blink = NULL;
                        newn = t;
                        continue;
                }

                /*
                 * The normal case -- we are inserting into the
                 * middle of the list.
                 */

                x = np;
                np = np->n_flink;
                x->n_flink = t;
                x->n_blink = t->n_blink;
                t->n_blink->n_flink = x;
                t->n_blink = x;
        }

        /*
         * Now the list headed up by new is sorted.
         * Go through it and remove duplicates.
         */

        np = newn;
        while (np != NULL) {
                t = np;
                while (t->n_flink != NULL &&
                       asccasecmp(np->n_name, t->n_flink->n_name) == 0)
                        t = t->n_flink;
                if (t == np || t == NULL) {
                        np = np->n_flink;
                        continue;
                }
                
                /*
                 * Now t points to the last entry with the same name
                 * as np.  Make np point beyond t.
                 */

                np->n_flink = t->n_flink;
                if (t->n_flink != NULL)
                        t->n_flink->n_blink = np;
                np = np->n_flink;
        }
        return (newn);
}

/*
 * Put another node onto a list of names and return
 * the list.
 */
static struct name *
put(struct name *list, struct name *node)
{
        node->n_flink = list;
        node->n_blink = NULL;
        if (list != NULL)
                list->n_blink = node;
        return(node);
}

/*
 * Determine the number of undeleted elements in
 * a name list and return it.
 */
int 
count(struct name *np)
{
        int c;

        for (c = 0; np != NULL; np = np->n_flink)
                if ((np->n_type & GDEL) == 0)
                        c++;
        return c;
}

/*
 * Delete the given name from a namelist.
 */
static struct name *
delname(struct name *np, char *name)
{
        struct name *p;

        for (p = np; p != NULL; p = p->n_flink)
                if (same_name(p->n_name, name)) {
                        if (p->n_blink == NULL) {
                                if (p->n_flink != NULL)
                                        p->n_flink->n_blink = NULL;
                                np = p->n_flink;
                                continue;
                        }
                        if (p->n_flink == NULL) {
                                if (p->n_blink != NULL)
                                        p->n_blink->n_flink = NULL;
                                continue;
                        }
                        p->n_blink->n_flink = p->n_flink;
                        p->n_flink->n_blink = p->n_blink;
                }
        return np;
}

/*
 * Pretty print a name list
 * Uncomment it if you need it.
 */

/*
void
prettyprint(struct name *name)
{
        struct name *np;

        np = name;
        while (np != NULL) {
                fprintf(stderr, "%s(%d) ", np->n_name, np->n_type);
                np = np->n_flink;
        }
        fprintf(stderr, "\n");
}
*/

struct name *
delete_alternates(struct name *np)
{
        struct name     *xp;
        char    **ap;

        np = delname(np, myname);
        if (altnames)
                for (ap = altnames; *ap; ap++)
                        np = delname(np, *ap);
        if ((xp = sextract(value("from"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        np = delname(np, xp->n_name);
                        xp = xp->n_flink;
                }
        if ((xp = sextract(value("replyto"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        np = delname(np, xp->n_name);
                        xp = xp->n_flink;
                }
        if ((xp = sextract(value("sender"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        np = delname(np, xp->n_name);
                        xp = xp->n_flink;
                }
        return np;
}

int
is_myname(char *name)
{
        struct name     *xp;
        char    **ap;

        if (same_name(myname, name))
                return 1;
        if (altnames)
                for (ap = altnames; *ap; ap++)
                        if (same_name(*ap, name))
                                return 1;
        if ((xp = sextract(value("from"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        if (same_name(xp->n_name, name))
                                return 1;
                        xp = xp->n_flink;
                }
        if ((xp = sextract(value("replyto"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        if (same_name(xp->n_name, name))
                                return 1;
                        xp = xp->n_flink;
                }
        if ((xp = sextract(value("sender"), GEXTRA|GSKIN)) != NULL)
                while (xp) {
                        if (same_name(xp->n_name, name))
                                return 1;
                        xp = xp->n_flink;
                }
        return 0;
}