/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 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/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <errno.h>

#include <unistd.h>
#include <syslog.h>
#include <libutil.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pathnames.h"
#ifdef USE_BLOCKLIST
#include <blocklist.h>
#endif

void logerr(const char *, ...) __printflike(1, 2) __dead2;

int
main(int argc, char *argv[])
{
        FILE *fp;
        int ch;
        char *lp;
        struct sockaddr_storage ss;
        socklen_t sval;
        int p[2], debug, kflag, logging, pflag, secure;
#define ENTRIES 50
        char **ap, *av[ENTRIES + 1], **comp, line[1024], *prog;
        char rhost[MAXHOSTNAMELEN];

        prog = _PATH_FINGER;
        debug = logging = kflag = pflag = secure = 0;
        openlog("fingerd", LOG_PID | LOG_CONS, LOG_DAEMON);
        opterr = 0;
        while ((ch = getopt(argc, argv, "dklp:s")) != -1)
                switch (ch) {
                case 'd':
                        debug = 1;
                        break;
                case 'k':
                        kflag = 1;
                        break;
                case 'l':
                        logging = 1;
                        break;
                case 'p':
                        prog = optarg;
                        pflag = 1;
                        break;
                case 's':
                        secure = 1;
                        break;
                case '?':
                default:
                        logerr("illegal option -- %c", optopt);
                }

        /*
         * Enable server-side Transaction TCP.
         */
        if (!debug) {
                int one = 1;
                if (setsockopt(STDOUT_FILENO, IPPROTO_TCP, TCP_NOPUSH, &one, 
                               sizeof one) < 0) {
                        logerr("setsockopt(TCP_NOPUSH) failed: %m");
                }
        }

        if (!fgets(line, sizeof(line), stdin))
                exit(1);

        if (!debug && (logging || pflag)) {
                sval = sizeof(ss);
                if (getpeername(0, (struct sockaddr *)&ss, &sval) < 0)
                        logerr("getpeername: %s", strerror(errno));
                realhostname_sa(rhost, sizeof rhost - 1,
                                (struct sockaddr *)&ss, sval);
                rhost[sizeof(rhost) - 1] = '\0';
                if (pflag)
                        setenv("FINGERD_REMOTE_HOST", rhost, 1);
        }

        if (logging) {
                char *t;
                char *end;

                end = memchr(line, 0, sizeof(line));
                if (end == NULL) {
                        if ((t = malloc(sizeof(line) + 1)) == NULL)
                                logerr("malloc: %s", strerror(errno));
                        memcpy(t, line, sizeof(line));
                        t[sizeof(line)] = 0;
                } else {
                        if ((t = strdup(line)) == NULL)
                                logerr("strdup: %s", strerror(errno));
                }
                for (end = t; *end; end++)
                        if (*end == '\n' || *end == '\r')
                                *end = ' ';
                syslog(LOG_NOTICE, "query from %s: `%s'", rhost, t);
        }

        comp = &av[2];
        av[3] = "--";
        if (kflag)
                *comp-- = "-k";
        for (lp = line, ap = &av[4];;) {
                *ap = strtok(lp, " \t\r\n");
                if (!*ap) {
                        if (secure && ap == &av[4]) {
#ifdef USE_BLOCKLIST
                                blocklist(1, STDIN_FILENO, "nousername");
#endif
                                puts("must provide username\r\n");
                                exit(1);
                        }
                        break;
                }
                if (secure && strchr(*ap, '@')) {
#ifdef USE_BLOCKLIST
                        blocklist(1, STDIN_FILENO, "noforwarding");
#endif
                        puts("forwarding service denied\r\n");
                        exit(1);
                }

                /* RFC742: "/[Ww]" == "-l" */
                if ((*ap)[0] == '/' && ((*ap)[1] == 'W' || (*ap)[1] == 'w')) {
                        *comp-- = "-l";
                }
                else if (++ap == av + ENTRIES) {
                        *ap = NULL;
                        break;
                }
                lp = NULL;
        }

        if ((lp = strrchr(prog, '/')) != NULL)
                *comp = ++lp;
        else
                *comp = prog;
        if (pipe(p) < 0)
                logerr("pipe: %s", strerror(errno));

        if (debug) {
                fprintf(stderr, "%s", prog);
                for (ap = comp; *ap != NULL; ++ap)
                        fprintf(stderr, " %s", *ap);
                fprintf(stderr, "\n");
        }

        switch(vfork()) {
        case 0:
                (void)close(p[0]);
                if (p[1] != STDOUT_FILENO) {
                        (void)dup2(p[1], STDOUT_FILENO);
                        (void)close(p[1]);
                }
                dup2(STDOUT_FILENO, STDERR_FILENO);

#ifdef USE_BLOCKLIST
                blocklist(0, STDIN_FILENO, "success");
#endif
                execv(prog, comp);
                write(STDERR_FILENO, prog, strlen(prog));
#define MSG ": cannot execute\n"
                write(STDERR_FILENO, MSG, strlen(MSG));
#undef MSG
                _exit(1);
        case -1:
                logerr("fork: %s", strerror(errno));
        }
        (void)close(p[1]);
        if (!(fp = fdopen(p[0], "r")))
                logerr("fdopen: %s", strerror(errno));
        while ((ch = getc(fp)) != EOF) {
                if (ch == '\n')
                        putchar('\r');
                putchar(ch);
        }
        exit(0);
}

#include <stdarg.h>

void
logerr(const char *fmt, ...)
{
        va_list ap;
        va_start(ap, fmt);
        (void)vsyslog(LOG_ERR, fmt, ap);
        va_end(ap);
        exit(1);
        /* NOTREACHED */
}