/*-
 * 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/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <err.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define ABUSEHOST       "whois.abuse.net"
#define ANICHOST        "whois.arin.net"
#define DENICHOST       "whois.denic.de"
#define DKNICHOST       "whois.dk-hostmaster.dk"
#define FNICHOST        "whois.afrinic.net"
#define GNICHOST        "whois.nic.gov"
#define IANAHOST        "whois.iana.org"
#define INICHOST        "whois.internic.net"
#define KNICHOST        "whois.krnic.net"
#define LNICHOST        "whois.lacnic.net"
#define MNICHOST        "whois.ra.net"
#define PDBHOST         "whois.peeringdb.com"
#define PNICHOST        "whois.apnic.net"
#define QNICHOST_TAIL   ".whois-servers.net"
#define RNICHOST        "whois.ripe.net"
#define VNICHOST        "whois.verisign-grs.com"

#define DEFAULT_PORT    "whois"

#define WHOIS_RECURSE   0x01
#define WHOIS_QUICK     0x02
#define WHOIS_SPAM_ME   0x04

#define CHOPSPAM        ">>> Last update of WHOIS database:"

#define ishost(h) (isalnum((unsigned char)h) || h == '.' || h == '-')

#define SCAN(p, end, check)                                     \
        while ((p) < (end))                                     \
                if (check) ++(p);                               \
                else break

static struct {
        const char *suffix, *server;
} whoiswhere[] = {
        /* Various handles */
        { "-ARIN", ANICHOST },
        { "-NICAT", "at" QNICHOST_TAIL },
        { "-NORID", "no" QNICHOST_TAIL },
        { "-RIPE", RNICHOST },
        /* Nominet's whois server doesn't return referrals to JANET */
        { ".ac.uk", "ac.uk" QNICHOST_TAIL },
        { ".gov.uk", "ac.uk" QNICHOST_TAIL },
        { "", IANAHOST }, /* default */
        { NULL, NULL } /* safety belt */
};

#define WHOIS_REFERRAL(s) { s, sizeof(s) - 1 }
static struct {
        const char *prefix;
        size_t len;
} whois_referral[] = {
        WHOIS_REFERRAL("whois:"), /* IANA */
        WHOIS_REFERRAL("Whois Server:"),
        WHOIS_REFERRAL("Registrar WHOIS Server:"), /* corporatedomains.com */
        WHOIS_REFERRAL("ReferralServer:  whois://"), /* ARIN */
        WHOIS_REFERRAL("ReferralServer:  rwhois://"), /* ARIN */
        WHOIS_REFERRAL("descr:          region. Please query"), /* AfriNIC */
        { NULL, 0 }
};

/*
 * We have a list of patterns for RIRs that assert ignorance rather than
 * providing referrals. If that happens, we guess that ARIN will be more
 * helpful. But, before following a referral to an RIR, we check if we have
 * asked that RIR already, and if so we make another guess.
 */
static const char *actually_arin[] = {
        "netname:        ERX-NETBLOCK\n", /* APNIC */
        "netname:        NON-RIPE-NCC-MANAGED-ADDRESS-BLOCK\n",
        NULL
};

static struct {
        int loop;
        const char *host;
} try_rir[] = {
        { 0, ANICHOST },
        { 0, RNICHOST },
        { 0, PNICHOST },
        { 0, FNICHOST },
        { 0, LNICHOST },
        { 0, NULL }
};

static void
reset_rir(void) {
        int i;

        for (i = 0; try_rir[i].host != NULL; i++)
                try_rir[i].loop = 0;
}

static const char *port = DEFAULT_PORT;

static const char *choose_server(char *);
static struct addrinfo *gethostinfo(const char *, const char *, int);
static void s_asprintf(char **ret, const char *format, ...) __printflike(2, 3);
static void usage(void) __dead2;
static void whois(const char *, const char *, const char *, int);

int
main(int argc, char *argv[])
{
        const char *country, *host;
        int ch, flags;

#ifdef  SOCKS
        SOCKSinit(argv[0]);
#endif

        country = host = NULL;
        flags = 0;
        while ((ch = getopt(argc, argv, "aAbc:fgh:iIklmp:PQrRS")) != -1) {
                switch (ch) {
                case 'a':
                        host = ANICHOST;
                        break;
                case 'A':
                        host = PNICHOST;
                        break;
                case 'b':
                        host = ABUSEHOST;
                        break;
                case 'c':
                        country = optarg;
                        break;
                case 'f':
                        host = FNICHOST;
                        break;
                case 'g':
                        host = GNICHOST;
                        break;
                case 'h':
                        host = optarg;
                        break;
                case 'i':
                        host = INICHOST;
                        break;
                case 'I':
                        host = IANAHOST;
                        break;
                case 'k':
                        host = KNICHOST;
                        break;
                case 'l':
                        host = LNICHOST;
                        break;
                case 'm':
                        host = MNICHOST;
                        break;
                case 'p':
                        port = optarg;
                        break;
                case 'P':
                        host = PDBHOST;
                        break;
                case 'Q':
                        flags |= WHOIS_QUICK;
                        break;
                case 'r':
                        host = RNICHOST;
                        break;
                case 'R':
                        flags |= WHOIS_RECURSE;
                        break;
                case 'S':
                        flags |= WHOIS_SPAM_ME;
                        break;
                case '?':
                default:
                        usage();
                        /* NOTREACHED */
                }
        }
        argc -= optind;
        argv += optind;

        if (!argc || (country != NULL && host != NULL))
                usage();

        /*
         * If no host or country is specified, rely on referrals from IANA.
         */
        if (host == NULL && country == NULL) {
                if ((host = getenv("WHOIS_SERVER")) == NULL &&
                    (host = getenv("RA_SERVER")) == NULL) {
                        if (!(flags & WHOIS_QUICK))
                                flags |= WHOIS_RECURSE;
                }
        }
        while (argc-- > 0) {
                if (country != NULL) {
                        char *qnichost;
                        s_asprintf(&qnichost, "%s%s", country, QNICHOST_TAIL);
                        whois(*argv, qnichost, port, flags);
                        free(qnichost);
                } else
                        whois(*argv, host != NULL ? host :
                              choose_server(*argv), port, flags);
                reset_rir();
                argv++;
        }
        exit(0);
}

static const char *
choose_server(char *domain)
{
        size_t len = strlen(domain);
        int i;

        for (i = 0; whoiswhere[i].suffix != NULL; i++) {
                size_t suffix_len = strlen(whoiswhere[i].suffix);
                if (len > suffix_len &&
                    strcasecmp(domain + len - suffix_len,
                               whoiswhere[i].suffix) == 0)
                        return (whoiswhere[i].server);
        }
        errx(EX_SOFTWARE, "no default whois server");
}

static struct addrinfo *
gethostinfo(const char *host, const char *hport, int exit_on_noname)
{
        struct addrinfo hints, *res;
        int error;

        memset(&hints, 0, sizeof(hints));
        hints.ai_flags = AI_CANONNAME;
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        res = NULL;
        error = getaddrinfo(host, hport, &hints, &res);
        if (error && (exit_on_noname || error != EAI_NONAME))
                err(EX_NOHOST, "%s: %s", host, gai_strerror(error));
        return (res);
}

/*
 * Wrapper for asprintf(3) that exits on error.
 */
static void
s_asprintf(char **ret, const char *format, ...)
{
        va_list ap;

        va_start(ap, format);
        if (vasprintf(ret, format, ap) == -1) {
                va_end(ap);
                err(EX_OSERR, "vasprintf()");
        }
        va_end(ap);
}

static int
connect_to_any_host(struct addrinfo *hostres)
{
        struct addrinfo *res;
        nfds_t i, j;
        size_t count;
        struct pollfd *fds;
        int timeout = 180, s = -1;

        for (res = hostres, count = 0; res; res = res->ai_next)
                count++;
        fds = calloc(count, sizeof(*fds));
        if (fds == NULL)
                err(EX_OSERR, "calloc()");

        /*
         * Traverse the result list elements and make non-block
         * connection attempts.
         */
        count = i = 0;
        for (res = hostres; res != NULL; res = res->ai_next) {
                s = socket(res->ai_family, res->ai_socktype | SOCK_NONBLOCK,
                    res->ai_protocol);
                if (s < 0)
                        continue;
                if (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
                        if (errno == EINPROGRESS) {
                                /* Add the socket to poll list */
                                fds[i].fd = s;
                                fds[i].events = POLLERR | POLLHUP |
                                                POLLIN | POLLOUT;
                                /*
                                 * From here until a socket connects, the
                                 * socket fd is owned by the fds[] poll array.
                                 */
                                s = -1;
                                count++;
                                i++;
                        } else {
                                close(s);
                                s = -1;

                                /*
                                 * Poll only if we have something to poll,
                                 * otherwise just go ahead and try next
                                 * address
                                 */
                                if (count == 0)
                                        continue;
                        }
                } else
                        goto done;

                /*
                 * If we are at the last address, poll until a connection is
                 * established or we failed all connection attempts.
                 */
                if (res->ai_next == NULL)
                        timeout = INFTIM;

                /*
                 * Poll the watched descriptors for successful connections:
                 * if we still have more untried resolved addresses, poll only
                 * once; otherwise, poll until all descriptors have errors,
                 * which will be considered as ETIMEDOUT later.
                 */
                do {
                        int n;

                        n = poll(fds, i, timeout);
                        if (n == 0) {
                                /*
                                 * No event reported in time.  Try with a
                                 * smaller timeout (but cap at 2-3ms)
                                 * after a new host have been added.
                                 */
                                if (timeout >= 3)
                                        timeout >>= 1;

                                break;
                        } else if (n < 0) {
                                /*
                                 * errno here can only be EINTR which we would
                                 * want to clean up and bail out.
                                 */
                                s = -1;
                                goto done;
                        }

                        /*
                         * Check for the event(s) we have seen.
                         */
                        for (j = 0; j < i; j++) {
                                if (fds[j].fd == -1 || fds[j].events == 0 ||
                                    fds[j].revents == 0)
                                        continue;
                                if (fds[j].revents & ~(POLLIN | POLLOUT)) {
                                        close(fds[j].fd);
                                        fds[j].fd = -1;
                                        fds[j].events = 0;
                                        count--;
                                        continue;
                                } else if (fds[j].revents & (POLLIN | POLLOUT)) {
                                        /* Connect succeeded. */
                                        s = fds[j].fd;
                                        fds[j].fd = -1;

                                        goto done;
                                }

                        }
                } while (timeout == INFTIM && count != 0);
        }

        /* All attempts were failed */
        s = -1;
        if (count == 0)
                errno = ETIMEDOUT;

done:
        /* Close all watched fds except the succeeded one */
        for (j = 0; j < i; j++)
                if (fds[j].fd != -1)
                        close(fds[j].fd);
        free(fds);
        return (s);
}

static void
whois(const char *query, const char *hostname, const char *hostport, int flags)
{
        FILE *fp;
        struct addrinfo *hostres;
        char *buf, *host, *nhost, *nport, *p;
        int comment, s, f;
        size_t len, i;

        hostres = gethostinfo(hostname, hostport, 1);
        s = connect_to_any_host(hostres);
        if (s == -1)
                err(EX_OSERR, "connect()");

        /* Restore default blocking behavior.  */
        if ((f = fcntl(s, F_GETFL)) == -1)
                err(EX_OSERR, "fcntl()");
        f &= ~O_NONBLOCK;
        if (fcntl(s, F_SETFL, f) == -1)
                err(EX_OSERR, "fcntl()");

        fp = fdopen(s, "r+");
        if (fp == NULL)
                err(EX_OSERR, "fdopen()");

        if (!(flags & WHOIS_SPAM_ME) &&
            (strcasecmp(hostname, DENICHOST) == 0 ||
             strcasecmp(hostname, "de" QNICHOST_TAIL) == 0)) {
                const char *q;
                int idn = 0;
                for (q = query; *q != '\0'; q++)
                        if (!isascii(*q))
                                idn = 1;
                fprintf(fp, "-T dn%s %s\r\n", idn ? "" : ",ace", query);
        } else if (!(flags & WHOIS_SPAM_ME) &&
                   (strcasecmp(hostname, DKNICHOST) == 0 ||
                    strcasecmp(hostname, "dk" QNICHOST_TAIL) == 0))
                fprintf(fp, "--show-handles %s\r\n", query);
        else if ((flags & WHOIS_SPAM_ME) ||
                 strchr(query, ' ') != NULL)
                fprintf(fp, "%s\r\n", query);
        else if (strcasecmp(hostname, ANICHOST) == 0) {
                if (strncasecmp(query, "AS", 2) == 0 &&
                    strspn(query+2, "0123456789") == strlen(query+2))
                        fprintf(fp, "+ a %s\r\n", query+2);
                else
                        fprintf(fp, "+ %s\r\n", query);
        } else if (strcasecmp(hostres->ai_canonname, VNICHOST) == 0)
                fprintf(fp, "domain %s\r\n", query);
        else
                fprintf(fp, "%s\r\n", query);
        fflush(fp);

        comment = 0;
        if (!(flags & WHOIS_SPAM_ME) &&
            (strcasecmp(hostname, ANICHOST) == 0 ||
             strcasecmp(hostname, RNICHOST) == 0)) {
                comment = 2;
        }

        nhost = NULL;
        while ((buf = fgetln(fp, &len)) != NULL) {
                /* Nominet */
                if (!(flags & WHOIS_SPAM_ME) &&
                    len == 5 && strncmp(buf, "-- \r\n", 5) == 0)
                        break;
                /* RIRs */
                if (comment == 1 && buf[0] == '#')
                        break;
                else if (comment == 2) {
                        if (strchr("#%\r\n", buf[0]) != NULL)
                                continue;
                        else
                                comment = 1;
                }

                printf("%.*s", (int)len, buf);

                if ((flags & WHOIS_RECURSE) && nhost == NULL) {
                        for (i = 0; whois_referral[i].prefix != NULL; i++) {
                                p = buf;
                                SCAN(p, buf+len, *p == ' ');
                                if (strncasecmp(p, whois_referral[i].prefix,
                                                   whois_referral[i].len) != 0)
                                        continue;
                                p += whois_referral[i].len;
                                SCAN(p, buf+len, *p == ' ');
                                host = p;
                                SCAN(p, buf+len, ishost(*p));
                                if (p > host) {
                                        char *pstr;

                                        s_asprintf(&nhost, "%.*s",
                                                   (int)(p - host), host);

                                        if (*p != ':') {
                                                s_asprintf(&nport, "%s", port);
                                                break;
                                        }

                                        pstr = ++p;
                                        SCAN(p, buf+len, isdigit(*p));
                                        if (p > pstr && (p - pstr) < 6) {
                                                s_asprintf(&nport, "%.*s",
                                                    (int)(p - pstr), pstr);
                                                break;
                                        }

                                        /* Invalid port; don't recurse */
                                        free(nhost);
                                        nhost = NULL;
                                }
                                break;
                        }
                        for (i = 0; actually_arin[i] != NULL; i++) {
                                if (strncmp(buf, actually_arin[i], len) == 0) {
                                        s_asprintf(&nhost, "%s", ANICHOST);
                                        s_asprintf(&nport, "%s", port);
                                        break;
                                }
                        }
                }
                /* Verisign etc. */
                if (!(flags & WHOIS_SPAM_ME) &&
                    len >= sizeof(CHOPSPAM)-1 &&
                    (strncasecmp(buf, CHOPSPAM, sizeof(CHOPSPAM)-1) == 0 ||
                     strncasecmp(buf, CHOPSPAM+4, sizeof(CHOPSPAM)-5) == 0)) {
                        printf("\n");
                        break;
                }
        }
        fclose(fp);
        freeaddrinfo(hostres);

        f = 0;
        for (i = 0; try_rir[i].host != NULL; i++) {
                /* Remember visits to RIRs */
                if (try_rir[i].loop == 0 &&
                    strcasecmp(try_rir[i].host, hostname) == 0)
                        try_rir[i].loop = 1;
                /* Do we need to find an alternative RIR? */
                if (try_rir[i].loop != 0 && nhost != NULL &&
                    strcasecmp(try_rir[i].host, nhost) == 0) {
                        free(nhost);
                        nhost = NULL;
                        free(nport);
                        nport = NULL;
                        f = 1;
                }
        }
        if (f) {
                /* Find a replacement RIR */
                for (i = 0; try_rir[i].host != NULL; i++) {
                        if (try_rir[i].loop == 0) {
                                s_asprintf(&nhost, "%s", try_rir[i].host);
                                s_asprintf(&nport, "%s", port);
                                break;
                        }
                }
        }
        if (nhost != NULL) {
                /* Ignore self-referrals */
                if (strcasecmp(hostname, nhost) != 0) {
                        printf("# %s\n\n", nhost);
                        whois(query, nhost, nport, flags);
                }
                free(nhost);
                free(nport);
        }
}

static void
usage(void)
{
        fprintf(stderr,
            "usage: whois [-aAbfgiIklmPQrRS] [-c country-code | -h hostname] "
            "[-p port] name ...\n");
        exit(EX_USAGE);
}