/*
**  NNTP server for readers (NNRP) for InterNetNews.
**
**  This server doesn't do any real load-limiting, except for what has
**  proven empirically necessary (i.e. look at GRPscandir).
*/

#include "portable/system.h"

#include "portable/setproctitle.h"
#include "portable/socket.h"
#include <netdb.h>
#include <signal.h>
#if defined(INN_BSDI_HOST)
#    include <netinet/tcp.h>
#endif

#if HAVE_GETSPNAM
#    include <shadow.h>
#endif
#include <sys/wait.h>

/* Needed on AIX 4.1 to get fd_set and friends. */
#if HAVE_SYS_SELECT_H
#    include <sys/select.h>
#endif

#include "inn/innconf.h"
#include "inn/libinn.h"
#include "inn/messages.h"
#include "inn/network-innbind.h"
#include "inn/network.h"
#include "inn/newsuser.h"
#include "inn/ov.h"
#include "inn/overview.h"
#include "inn/secrets.h"
#include "inn/version.h"

/* Silent this warning because of the way we deal with EXTERN. */
#if defined(__llvm__) || defined(__clang__)
#    pragma GCC diagnostic ignored "-Wmissing-variable-declarations"
#endif

#define MAINLINE
#include "nnrpd.h"

#include "tls.h"

#if defined(HAVE_OPENSSL) || defined(HAVE_SASL)
bool encryption_layer_on = false;
#endif

/* Optional arguments for getopt. */
#if defined(HAVE_BLOCKLIST)
#    define BLOCKLIST_OPT "B"
#else
#    define BLOCKLIST_OPT ""
#endif

#if defined(HAVE_OPENSSL)
#    define OPENSSL_OPT "S"
#else
#    define OPENSSL_OPT ""
#endif

static void Usage(void) __attribute__((__noreturn__));

/*
**  If we have getloadavg, include the appropriate header file.  Otherwise,
**  just assume that we always have a load of 0.
*/
#if HAVE_GETLOADAVG
#    if HAVE_SYS_LOADAVG_H
#        include <sys/loadavg.h>
#    endif
#else
static int
getloadavg(double loadavg[], int nelem)
{
    int i;

    for (i = 0; i < nelem && i < 3; i++)
        loadavg[i] = 0;
    return i;
}
#endif


#define CMDany -1


typedef struct _CMDENT {
    const char *Name;
    void (*Function)(int, char **);
    bool Needauth;
    int Minac;
    int Maxac;
    bool Stripspaces;
    const char *Help;
} CMDENT;


char *ACTIVE = NULL;
char *ACTIVETIMES = NULL;
char *HISTORY = NULL;
char *NEWSGROUPS = NULL;
char *NNRPACCESS = NULL;

static char *LocalLogFileName = NULL;
static char *LocalLogDirName;

static double STATstart;
static double STATfinish;
static char *PushedBack;
static sig_atomic_t ChangeTrace;
static bool DaemonMode = false;
static bool ForeGroundMode = false;
static const char *HostErrorStr;
static bool GetHostByAddr = true; /* Formerly DO_NNRP_GETHOSTBYADDR. */
const char *NNRPinstance = "";

/* Default values for the syntaxchecks parameter in inn.conf. */
bool laxmid = false;

/* Other default values. */
bool Tracing = false;

#ifdef DO_PERL
bool PerlLoaded = false;
#endif

#ifdef DO_PYTHON
bool PY_use_dynamic = false;
#endif

static char CMDfetchhelp[] = "[message-ID|number]";


/*
**  { command base name, function to call, need authentication,
**    min args, max args, strip spaces, help string }
*/
static CMDENT CMDtable[] = {
    {"ARTICLE",      CMDfetch,        true,  1, 2,      true,  CMDfetchhelp               },
    /* Parse AUTHINFO in a special way so as to keep white spaces
     * in usernames and passwords. */
    {"AUTHINFO",     CMDauthinfo,     false, 3, CMDany, false,
     "USER name|PASS password"
#ifdef HAVE_SASL
     "|SASL mechanism [initial-response]"
#endif
     "|GENERIC program [argument ...]"                                                    },
    {"BODY",         CMDfetch,        true,  1, 2,      true,  CMDfetchhelp               },
    {"CAPABILITIES", CMDcapabilities, false, 1, 2,      true,  "[keyword]"                },
#if defined(HAVE_ZLIB)
    {"COMPRESS",     CMDcompress,     false, 2, 2,      true,  "DEFLATE"                  },
#endif
    {"DATE",         CMDdate,         false, 1, 1,      true,  NULL                       },
    {"GROUP",        CMDgroup,        true,  2, 2,      true,  "newsgroup"                },
    {"HDR",          CMDpat,          true,  2, 3,      true,  "header [message-ID|range]"},
    {"HEAD",         CMDfetch,        true,  1, 2,      true,  CMDfetchhelp               },
    {"HELP",         CMDhelp,         false, 1, 1,      true,  NULL                       },
    {"IHAVE",        CMDpost,         true,  2, 2,      true,  "message-ID"               },
    {"LAST",         CMDnextlast,     true,  1, 1,      true,  NULL                       },
    {"LIST",         CMDlist,         true,  1, 3,      true,
     "[ACTIVE [wildmat]|ACTIVE.TIMES [wildmat]|COUNTS [wildmat]|DISTRIB.PATS"
     "|DISTRIBUTIONS|HEADERS [MSGID|RANGE]|MODERATORS|MOTD|NEWSGROUPS "
     "[wildmat]|OVERVIEW.FMT|SUBSCRIPTIONS [wildmat]]"                                    },
    {"LISTGROUP",    CMDgroup,        true,  1, 3,      true,  "[newsgroup [range]]"      },
    {"MODE",         CMDmode,         false, 2, 2,      true,  "READER"                   },
    {"NEWGROUPS",    CMDnewgroups,    true,  3, 4,      true,  "[yy]yymmdd hhmmss [GMT]"  },
    {"NEWNEWS",      CMDnewnews,      true,  4, 5,      true,
     "wildmat [yy]yymmdd hhmmss [GMT]"                                                    },
    {"NEXT",         CMDnextlast,     true,  1, 1,      true,  NULL                       },
    {"OVER",         CMDover,         true,  1, 2,      true,  "[range]"                  },
    {"POST",         CMDpost,         true,  1, 1,      true,  NULL                       },
    {"QUIT",         CMDquit,         false, 1, 1,      true,  NULL                       },
    /* SLAVE (which was ill-defined in RFC 977) was removed from the NNTP
     * protocol in RFC 3977. */
    {"SLAVE",        CMD_unimp,       false, 1, 1,      true,  NULL                       },
#ifdef HAVE_OPENSSL
    {"STARTTLS",     CMDstarttls,     false, 1, 1,      true,  NULL                       },
#endif
    {"STAT",         CMDfetch,        true,  1, 2,      true,  CMDfetchhelp               },
    {"XGTITLE",      CMDxgtitle,      true,  1, 2,      true,  "[wildmat]"                },
    {"XHDR",         CMDpat,          true,  2, 3,      true,  "header [message-ID|range]"},
    {"XOVER",        CMDover,         true,  1, 2,      true,  "[range]"                  },
    {"XPAT",         CMDpat,          true,  4, CMDany, true,
     "header message-ID|range pattern [pattern ...]"                                      },
    {NULL,           CMD_unimp,       false, 0, 0,      true,  NULL                       }
};

static const char *const timer_name[] = {
    "idle", "newnews", "readart", "checkart", "nntpread", "nntpwrite",
};


/*
**  Log a summary status message and exit.
*/
void
ExitWithStats(int x, bool readconf)
{
    double usertime;
    double systime;

    line_free(&NNTPline);
    fflush(stdout);
    STATfinish = TMRnow_double();
    if (GetResourceUsage(&usertime, &systime) < 0) {
        usertime = 0;
        systime = 0;
    }

    GRPreport();
    if (ARTcount)
        syslog(L_NOTICE, "%s exit articles %lu groups %ld", Client.host,
               ARTcount, GRPcount);
    if (POSTreceived || POSTrejected)
        syslog(L_NOTICE, "%s posts received %ld rejected %ld", Client.host,
               POSTreceived, POSTrejected);
    syslog(L_NOTICE, "%s times user %.3f system %.3f idle %.3f elapsed %.3f",
           Client.host, usertime, systime, IDLEtime, STATfinish - STATstart);
    /* Tracking code - Make entries in the logfile(s) to show that we have
     * finished with this session. */
    if (!readconf && PERMaccessconf && PERMaccessconf->readertrack) {
        syslog(L_NOTICE, "%s Tracking Disabled (%s)", Client.host, Username);
        if (LLOGenable) {
            fprintf(locallog, "%s Tracking Disabled (%s)\n", Client.host,
                    Username);
            fclose(locallog);
            syslog(L_NOTICE, "%s Local Logging ends (%s) %s", Client.host,
                   Username, LocalLogFileName);
        }
    }
    if (ARTget)
        syslog(L_NOTICE, "%s artstats get %ld time %ld size %ld", Client.host,
               ARTget, ARTgettime, ARTgetsize);
    if (!readconf && PERMaccessconf && PERMaccessconf->nnrpdoverstats
        && OVERcount)
        syslog(L_NOTICE,
               "%s overstats count %ld hit %ld miss %ld time %ld size %ld dbz "
               "%ld seek %ld get %ld artcheck %ld",
               Client.host, OVERcount, OVERhit, OVERmiss, OVERtime, OVERsize,
               OVERdbz, OVERseek, OVERget, OVERartcheck);

#ifdef HAVE_OPENSSL
    if (tls_conn) {
        SSL_shutdown(tls_conn);
        SSL_free(tls_conn);
        tls_conn = NULL;
    }
#endif

#ifdef HAVE_SASL
    if (sasl_conn) {
        sasl_dispose(&sasl_conn);
        sasl_conn = NULL;
        sasl_ssf = 0;
        sasl_maxout = NNTP_MAXLEN_COMMAND;
    }
    sasl_done();
#endif /* HAVE_SASL */

#if defined(HAVE_ZLIB)
    if (compression_layer_on) {
        inflateEnd(zstream_in);
        free(zstream_in);
        free(zbuf_in);
        deflateEnd(zstream_out);
        free(zstream_out);
        free(zbuf_out);
    }
#endif /* HAVE_ZLIB */

    if (DaemonMode) {
        shutdown(STDIN_FILENO, 2);
        shutdown(STDOUT_FILENO, 2);
        shutdown(STDERR_FILENO, 2);
        close(STDIN_FILENO);
        close(STDOUT_FILENO);
        close(STDERR_FILENO);
    }

    OVclose();
    SMshutdown();

#ifdef DO_PYTHON
    PY_close_python();
#endif /* DO_PYTHON */

    if (History)
        HISclose(History);

    if (innconf->timer != 0) {
        TMRsummary(Client.host, timer_name);
        TMRfree();
    }

    if (LocalLogFileName != NULL)
        free(LocalLogFileName);
    closelog();
    exit(x);
}


/*
**  The HELP command.
*/
void
CMDhelp(int ac UNUSED, char *av[] UNUSED)
{
    CMDENT *cp;
    char *p, *q;
    static const char *newsmaster = NEWSMASTER;

    Reply("%d Legal commands\r\n", NNTP_INFO_HELP);
    for (cp = CMDtable; cp->Name; cp++) {
        if (cp->Function == CMD_unimp)
            continue;
        if (cp->Help == NULL)
            Printf("  %s\r\n", cp->Name);
        else
            Printf("  %s %s\r\n", cp->Name, cp->Help);
    }
    if (PERMaccessconf && (VirtualPathlen > 0)) {
        if (PERMaccessconf->newsmaster) {
            if (strchr(PERMaccessconf->newsmaster, '@') == NULL) {
                Printf("Report problems to <%s@%s>.\r\n",
                       PERMaccessconf->newsmaster, PERMaccessconf->domain);
            } else {
                Printf("Report problems to <%s>.\r\n",
                       PERMaccessconf->newsmaster);
            }
        } else {
            /* Sigh, pickup from newsmaster anyway. */
            if ((p = strchr(newsmaster, '@')) == NULL)
                Printf("Report problems to <%s@%s>.\r\n", newsmaster,
                       PERMaccessconf->domain);
            else {
                q = xstrndup(newsmaster, p - newsmaster);
                Printf("Report problems to <%s@%s>.\r\n", q,
                       PERMaccessconf->domain);
                free(q);
            }
        }
    } else {
        if (strchr(newsmaster, '@') == NULL)
            Printf("Report problems to <%s@%s>.\r\n", newsmaster,
                   innconf->fromhost);
        else
            Printf("Report problems to <%s>.\r\n", newsmaster);
    }
    Printf(".\r\n");
}


/*
**  The CAPABILITIES command.
**
**  nnrpd does not advertise the MODE-READER capability; only innd may
**  advertise it.
*/
void
CMDcapabilities(int ac, char *av[])
{
#ifdef HAVE_SASL
    const char *mechlist = NULL;
#endif

    if (ac == 2 && !IsValidKeyword(av[1])) {
        Reply("%d Syntax error in keyword\r\n", NNTP_ERR_SYNTAX);
        return;
    }

    Reply("%d Capability list:\r\n", NNTP_INFO_CAPABILITIES);

    Printf("VERSION 2\r\n");

    Printf("IMPLEMENTATION %s\r\n", INN_VERSION_STRING);

#ifdef HAVE_SASL
    /* Check for available SASL mechanisms.
     * Start the string with a space for the strstr() calls afterwards. */
    sasl_listmech(sasl_conn, NULL, " ", " ", "", &mechlist, NULL, NULL);
#endif

    /* The client is not already authenticated. */
    if ((!PERMauthorized || PERMneedauth || PERMcanauthenticate)) {
        Printf("AUTHINFO");

        /* No arguments if the server does not permit any authentication
         * commands in its current state (either a compression layer other
         * than the one negotiated along with TLS is active, or the user
         * has no way to authenticate successfully). */
        if (
#if defined(HAVE_ZLIB)
            (!compression_layer_on || tls_compression_on) &&
#endif /* HAVE_ZLIB */
            PERMcanauthenticate) {
#ifdef HAVE_OPENSSL
            if (PERMcanauthenticatewithoutSSL || encryption_layer_on) {
#endif
                /* AUTHINFO USER is advertised only if a TLS layer is active,
                 * if compiled with TLS support. */
                Printf(" USER");
#ifdef HAVE_OPENSSL
            } else {
#    ifdef HAVE_SASL
                /* Remove insecure PLAIN, LOGIN and EXTERNAL SASL mechanisms,
                 * if compiled with TLS support and a TLS layer is not active.
                 */
                if (mechlist != NULL) {
                    char *p;

                    if ((p = strstr(mechlist, " PLAIN")) != NULL
                        && (p[6] == '\0' || p[6] == ' ')) {
                        memmove(p, p + 6, strlen(p) - 5);
                    }
                    if ((p = strstr(mechlist, " LOGIN")) != NULL
                        && (p[6] == '\0' || p[6] == ' ')) {
                        memmove(p, p + 6, strlen(p) - 5);
                    }
                    if ((p = strstr(mechlist, " EXTERNAL")) != NULL
                        && (p[9] == '\0' || p[9] == ' ')) {
                        memmove(p, p + 9, strlen(p) - 8);
                    }
                }
#    endif /* HAVE_SASL */
            }
#endif /* HAVE_OPENSSL */
#ifdef HAVE_SASL
            /* Check whether at least one SASL mechanism is available. */
            if (mechlist != NULL && strlen(mechlist) > 2) {
                Printf(" SASL");
            }
#endif
        }
        Printf("\r\n");
    }

#if defined(HAVE_ZLIB)
    /* A compression layer is not active. */
    if (!compression_layer_on) {
        Printf("COMPRESS DEFLATE\r\n");
    }
#endif /* HAVE_ZLIB */

    if (PERMcanread) {
        Printf("HDR\r\n");
    }

    if (PERMaccessconf->allowihave && PERMcanpost) {
        Printf("IHAVE\r\n");
    }

    Printf(
        "LIST ACTIVE ACTIVE.TIMES COUNTS DISTRIB.PATS DISTRIBUTIONS"
        " HEADERS MODERATORS MOTD NEWSGROUPS OVERVIEW.FMT SUBSCRIPTIONS\r\n");

    if (PERMaccessconf->allownewnews && PERMcanread) {
        Printf("NEWNEWS\r\n");
    }

    if (PERMcanread) {
        Printf("OVER\r\n");
    }

    if (PERMcanpost) {
        Printf("POST\r\n");
    }

    Printf("READER\r\n");

#if defined(HAVE_SASL)
    /* Check whether at least one SASL mechanism is available.
     * The SASL capability has to be advertised, even after authentication,
     * so that the client can detect a possible active down-negotiation
     * attack. */
    if (mechlist != NULL && strlen(mechlist) > 2) {
        Printf("SASL%s\r\n", mechlist);
    }
#endif /* HAVE_SASL */

#if defined(HAVE_OPENSSL)
    /* A TLS layer is not active, a compression layer is not active,
     * and the client is not already authenticated. */
    if (!encryption_layer_on
#    if defined(HAVE_ZLIB)
        && !compression_layer_on
#    endif /* HAVE_ZLIB */
        && (!PERMauthorized || PERMneedauth || PERMcanauthenticate)) {
        Printf("STARTTLS\r\n");
    }
#endif /* HAVE_OPENSSL */

    if (PERMcanread) {
        Printf("XPAT\r\n");
    }

    Printf(".\r\n");
}


/*
**  Catch-all for unimplemented functions.
*/
void
CMD_unimp(int ac UNUSED, char *av[])
{
    Reply("%d \"%s\" not implemented; try \"HELP\"\r\n", NNTP_ERR_COMMAND,
          av[0]);
}


/*
**  The QUIT command.
*/
void
CMDquit(int ac UNUSED, char *av[] UNUSED)
{
    Reply("%d Bye!\r\n", NNTP_OK_QUIT);
    ExitWithStats(0, false);
}


/*
**  Convert an address to a hostname.  Don't trust the reverse lookup
**  since anyone can fake reverse DNS entries.
*/
static bool
Address2Name(struct sockaddr *sa, socklen_t len, char *hostname, size_t size)
{
    static const char MISMATCH[] = "reverse lookup validation failed";
    struct addrinfo hints, *ai, *host;
    char *p;
    int ret;
    bool valid = false;

    /* Get the official hostname, store it away. */
    ret = getnameinfo(sa, len, hostname, size, NULL, 0, NI_NAMEREQD);
    if (ret != 0) {
        HostErrorStr = gai_strerror(ret);
        return false;
    }

    /* Get addresses for this host. */
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    ret = getaddrinfo(hostname, NULL, &hints, &ai);
    if (ret != 0) {
        HostErrorStr = gai_strerror(ret);
        return false;
    }

    /* Make sure one of those addresses is the address we got. */
    for (host = ai; host != NULL; host = host->ai_next)
        if (network_sockaddr_equal(sa, host->ai_addr)) {
            valid = true;
            break;
        }
    freeaddrinfo(ai);

    /* Lowercase the returned name since wildmats are case-sensitive. */
    if (valid) {
        for (p = hostname; *p != '\0'; p++)
            if (isupper((unsigned char) *p))
                *p = tolower((unsigned char) *p);
        return true;
    } else {
        HostErrorStr = MISMATCH;
        return false;
    }
}


/*
**  Determine hostname and IP of the client, amongst other information.
*/
static void
GetClientInfo(unsigned short port)
{
    static const char *default_host_error = "unknown error";
    struct sockaddr_storage ssc, sss;
    struct sockaddr *sac = (struct sockaddr *) &ssc;
    struct sockaddr *sas = (struct sockaddr *) &sss;
    socklen_t length;
    size_t size;

    memset(&Client, 0, sizeof(Client));
    strlcpy(Client.host, "?", sizeof(Client.host));

    /* Get the peer's name. */
    length = sizeof(ssc);
    if (getpeername(STDIN_FILENO, sac, &length) < 0) {
        if (!isatty(STDIN_FILENO)) {
            sysnotice("? can't getpeername");
            Reply("%d Can't get your name.  Goodbye!\r\n", NNTP_ERR_ACCESS);
            ExitWithStats(1, true);
        }
        strlcpy(Client.host, "localhost", sizeof(Client.host));
    } else {
        /* Figure out client's IP address/hostname. */
        HostErrorStr = default_host_error;
        if (!network_sockaddr_sprint(Client.ip, sizeof(Client.ip), sac)) {
            notice("? can't get client numeric address: %s", HostErrorStr);
            Reply("%d Can't get your numeric address.  Goodbye!\r\n",
                  NNTP_ERR_ACCESS);
            ExitWithStats(1, true);
        }
        if (GetHostByAddr) {
            HostErrorStr = default_host_error;
            if (!Address2Name(sac, length, Client.host, sizeof(Client.host))) {
                notice("? reverse lookup for %s failed: %s -- using IP"
                       " address for access",
                       Client.ip, HostErrorStr);
                strlcpy(Client.host, Client.ip, sizeof(Client.host));
            }
        } else {
            strlcpy(Client.host, Client.ip, sizeof(Client.host));
        }

        /* Figure out server's IP address/hostname. */
        length = sizeof(sss);
        if (getsockname(STDIN_FILENO, sas, &length) < 0) {
            sysnotice("%s can't getsockname", Client.host);
            Reply("%d Can't figure out where you connected to.  Goodbye!\r\n",
                  NNTP_ERR_ACCESS);
            ExitWithStats(1, true);
        }
        HostErrorStr = default_host_error;
        size = sizeof(Client.serverip);
        if (!network_sockaddr_sprint(Client.serverip, size, sas)) {
            notice("? can't get server numeric address: %s", HostErrorStr);
            Reply("%d Can't get my own numeric address.  Goodbye!\r\n",
                  NNTP_ERR_ACCESS);
            ExitWithStats(1, true);
        }
        if (GetHostByAddr) {
            HostErrorStr = default_host_error;
            size = sizeof(Client.serverhost);
            if (!Address2Name(sas, length, Client.serverhost, size)) {
                notice("? reverse lookup for %s failed: %s -- using IP"
                       " address for access",
                       Client.serverip, HostErrorStr);
                strlcpy(Client.serverhost, Client.serverip,
                        sizeof(Client.serverhost));
            }
        } else {
            strlcpy(Client.serverhost, Client.serverip,
                    sizeof(Client.serverhost));
        }

        /* Get port numbers. */
        Client.port = network_sockaddr_port(sac);
        Client.serverport = network_sockaddr_port(sas);
    }

#if defined(INN_BSDI_HOST)
    /* Setting TCP_NODELAY to nnrpd fixes a problem of slow downloading
     * of overviews and slow answers on some architectures (like BSD/OS
     * where TCP delayed acknowledgements are enabled). */
    int nodelay = 1;
    setsockopt(STDIN_FILENO, IPPROTO_TCP, TCP_NODELAY, &nodelay,
               sizeof(nodelay));
#endif

    notice("%s (%s) connect - port %u", Client.host, Client.ip, port);
}


/*
**  Write a buffer, via compression layer and/or SASL security layer
**  and/or TLS if necessary.
*/
void
write_buffer(const char *buff, ssize_t len)
{
    const char *p;
    ssize_t n;

    TMRstart(TMR_NNTPWRITE);
    p = buff;

#if defined(HAVE_ZLIB)
    if (compression_layer_on) {
        int r;

        zstream_out->next_in = (unsigned char *) p;
        zstream_out->avail_in = len;
        zstream_out->next_out = zbuf_out;
        zstream_out->avail_out = zbuf_out_size;

        do {
            /* Grow the output buffer if needed. */
            if (zstream_out->avail_out == 0) {
                size_t newsize = zbuf_out_size * 2;
                zbuf_out = xrealloc(zbuf_out, newsize);
                zstream_out->next_out = zbuf_out + zbuf_out_size;
                zstream_out->avail_out = zbuf_out_size;
                zbuf_out_size = newsize;
            }

            r = deflate(zstream_out,
                        zstream_flush_needed ? Z_PARTIAL_FLUSH : Z_NO_FLUSH);

            if (!(r == Z_OK || r == Z_BUF_ERROR || r == Z_STREAM_END)) {
                sysnotice("deflate() failed: %d; %s", r,
                          zstream_out->msg != NULL ? zstream_out->msg
                                                   : "no detail");
                TMRstop(TMR_NNTPWRITE);
                return;
            }
        } while (r == Z_OK && zstream_out->avail_out == 0);

        p = (char *) zbuf_out;
        len = zbuf_out_size - zstream_out->avail_out;
        zstream_flush_needed = false;
    }
#endif /* HAVE_ZLIB */

    while (len > 0) {
        const char *out;
        unsigned outlen;

#if defined(HAVE_SASL)
        if (sasl_conn != NULL && sasl_ssf > 0) {
            int r;

            /* Can only encode as much as the client can handle at one time. */
            n = (len > sasl_maxout) ? sasl_maxout : len;
            if ((r = sasl_encode(sasl_conn, p, n, &out, &outlen)) != SASL_OK) {
                const char *ed = sasl_errdetail(sasl_conn);

                sysnotice("sasl_encode() failed: %s; %s",
                          sasl_errstring(r, NULL, NULL),
                          ed != NULL ? ed : "no detail");
                TMRstop(TMR_NNTPWRITE);
                return;
            }
        } else
#endif /* HAVE_SASL */
        {
            /* Output the entire unencoded string. */
            n = len;
            out = p;
            outlen = len;
        }

        len -= n;
        p += n;

#ifdef HAVE_OPENSSL
        if (tls_conn) {
            int r;

        Again:
            r = SSL_write(tls_conn, out, outlen);
            switch (SSL_get_error(tls_conn, r)) {
            case SSL_ERROR_NONE:
                break;
            case SSL_ERROR_WANT_WRITE:
                goto Again;
                /* NOTREACHED */
            case SSL_ERROR_ZERO_RETURN:
                SSL_shutdown(tls_conn);
                goto fallthrough;
            case SSL_ERROR_SSL:
            case SSL_ERROR_SYSCALL:
            fallthrough:
                /* SSL_shutdown() must not be called. */
                tls_conn = NULL;
                errno = ECONNRESET;
                break;
            }
        } else
#endif /* HAVE_OPENSSL */
            do {
                n = write(STDIN_FILENO, out, outlen);
            } while (n == -1 && errno == EINTR);
    }

    TMRstop(TMR_NNTPWRITE);
}


/*
**  Send formatted output, possibly with debugging output.
*/
static void __attribute__((__format__(printf, 1, 0)))
VPrintf(const char *fmt, va_list args, int dotrace)
{
    char buff[2048], *p;
    ssize_t len;

    len = vsnprintf(buff, sizeof(buff), fmt, args);
    if (len < 0)
        len = 0;
    else if ((size_t) len >= sizeof(buff))
        len = sizeof(buff) - 1;
    write_buffer(buff, len);

    if (dotrace && Tracing) {
        int oerrno = errno;

        /* Copy output, but strip trailing CR-LF.  Note we're assuming here
         * that no output line can ever be longer than 2045 characters. */
        p = buff + strlen(buff) - 1;
        while (p >= buff && (*p == '\n' || *p == '\r'))
            *p-- = '\0';
        syslog(L_TRACE, "%s > %s", Client.host, buff);

        errno = oerrno;
    }
}


/*
**  Send a reply, possibly with debugging output.
**  Reply() is used for answers which can possibly be traced (response codes).
**  Printf() is used in other cases.
*/
void
Reply(const char *fmt, ...)
{
    va_list args;

#if defined(HAVE_ZLIB)
    /* For single-line responses, immediately flush the output stream. */
    zstream_flush_needed = true;
#endif /* HAVE_ZLIB */

    va_start(args, fmt);
    VPrintf(fmt, args, 1);
    va_end(args);
}

void
Printf(const char *fmt, ...)
{
    va_list args;

#if defined(HAVE_ZLIB)
    /* Last line of a multi-line data block response.
     * Time to flush the compressed output stream.
     * Check that only when the compression layer is active. */
    if (compression_layer_on && strlen(fmt) == 3
        && strcasecmp(fmt, ".\r\n") == 0) {
        zstream_flush_needed = true;
    }
#endif /* HAVE_ZLIB */

    va_start(args, fmt);
    VPrintf(fmt, args, 0);
    va_end(args);
}


#ifdef HAVE_SIGACTION
#    define NO_SIGACTION_UNUSED UNUSED
#else
#    define NO_SIGACTION_UNUSED
#endif


/*
**  Got a signal; toggle tracing.
*/
static void
ToggleTrace(int s NO_SIGACTION_UNUSED)
{
    ChangeTrace = true;
#ifndef HAVE_SIGACTION
    xsignal(s, ToggleTrace);
#endif
}

/*
**  Got a SIGPIPE; exit cleanly.
*/
__attribute__((__noreturn__)) static void
CatchPipe(int s UNUSED)
{
    ExitWithStats(0, false);
}


/*
**  Got a signal; wait for children.
*/
static void
WaitChild(int s NO_SIGACTION_UNUSED)
{
    int pid;

    for (;;) {
        pid = waitpid(-1, NULL, WNOHANG);
        if (pid <= 0)
            break;
    }
#ifndef HAVE_SIGACTION
    xsignal(s, WaitChild);
#endif
}


static void
SetupDaemon(void)
{
    bool val;

    val = true;
    if (SMsetup(SM_PREOPEN, (void *) &val) && !SMinit()) {
        syslog(L_NOTICE, "can't initialize storage method, %s", SMerrorstr);
        Reply("%d NNTP server unavailable.  Try later!\r\n",
              NNTP_FAIL_TERMINATING);
        ExitWithStats(1, true);
    }
    OVextra = overview_extra_fields(false);
    if (OVextra == NULL) {
        /* overview_extra_fields() should already have logged something
         * useful. */
        Reply("%d NNTP server unavailable.  Try later!\r\n",
              NNTP_FAIL_TERMINATING);
        ExitWithStats(1, true);
    }
    overhdr_xref = overview_index("Xref", OVextra);
    if (!OVopen(OV_READ)) {
        /* This shouldn't really happen. */
        syslog(L_NOTICE, "can't open overview %m");
        Reply("%d NNTP server unavailable.  Try later!\r\n",
              NNTP_FAIL_TERMINATING);
        ExitWithStats(1, true);
    }
    if (!OVctl(OVCACHEKEEP, &val)) {
        syslog(L_NOTICE, "can't enable overview cache %m");
        Reply("%d NNTP server unavailable.  Try later!\r\n",
              NNTP_FAIL_TERMINATING);
        ExitWithStats(1, true);
    }
}


/*
**  Print a usage message and exit.
*/
static void
Usage(void)
{
    fprintf(stderr, "Usage error.\n");
    exit(1);
}


int
main(int argc, char *argv[])
{
    const char *name;
    CMDENT *cp;
    char buff[NNTP_MAXLEN_COMMAND];
    char **av;
    int ac;
    READTYPE r;
    int i;
    unsigned int j;
    char **v;
    char *Reject;
    int timeout;
    unsigned int vid = 0;
    int count = 123456789;
    struct timeval tv;
    unsigned short ListenPort = NNTP_PORT;
    char *ListenAddr = NULL;
    char *ListenAddr6 = NULL;
    int *lfds;
    fd_set lfdset, lfdsetread;
    unsigned int lfdcount;
    int lfdreadcount;
    bool lfdokay;
    int lfdmax = 0;
    int fd = -1;
    pid_t pid = -1;
    FILE *pidfile;
    int clienttimeout;
    char *ConfFile = NULL;
    char *path;
    bool validcommandtoolong;

    int respawn = 0;

    setproctitle_init(argc, argv);

    /* Parse arguments.  Must xstrdup() optarg if used because setproctitle
     * may clobber it! */
    Reject = NULL;
    LLOGenable = false;
    GRPcur = NULL;
    MaxBytesPerSecond = 0;
    strlcpy(Username, "unknown", sizeof(Username));

    /* Set up the pathname, first thing, and teach our error handlers about
     * the name of the program. */
    name = argv[0];
    if (name == NULL || *name == '\0')
        name = "nnrpd";
    else {
        const char *p;

        /* We take the last "/" in the path. */
        p = strrchr(name, '/');
        if (p != NULL)
            name = p + 1;
    }
    message_program_name = xstrdup(name);
    openlog(message_program_name, L_OPENLOG_FLAGS | LOG_PID, LOG_INN_PROG);
    message_handlers_die(1, message_log_syslog_crit);
    message_handlers_warn(1, message_log_syslog_warning);
    message_handlers_notice(1, message_log_syslog_notice);

    if (!innconf_read(NULL))
        exit(1);

#ifdef HAVE_SASL
    if (sasl_server_init(sasl_callbacks, "INN") != SASL_OK) {
        syslog(L_FATAL, "sasl_server_init() failed");
        exit(1);
    }
#endif /* HAVE_SASL */

    while ((i = getopt(argc, argv,
                       "4:6:b:" BLOCKLIST_OPT "c:Dfi:I:nop:P:r:s:" OPENSSL_OPT
                       "t"))
           != EOF)
        switch (i) {
        default:
            Usage();
            /* NOTREACHED */
        case '4': /* Bind to a certain IPv4 address. */
        case 'b':
            if (ListenAddr != NULL)
                die("-b and -4 are the same and both may not be given");
            ListenAddr = xstrdup(optarg);
            break;
        case '6': /* Bind to a certain IPv6 address. */
            ListenAddr6 = xstrdup(optarg);
            break;
#if defined(HAVE_BLOCKLIST)
        case 'B': /* Enable blocklistd functionality. */
            BlocklistEnabled = true;
            break;
#endif            /* HAVE_BLOCKLIST */
        case 'c': /* Use alternate readers.conf. */
            ConfFile = concatpath(innconf->pathetc, optarg);
            break;
        case 'D': /* Standalone daemon mode. */
            DaemonMode = true;
            break;
        case 'P': /* Prespawn count in daemon mode. */
            respawn = atoi(optarg);
            break;
        case 'f': /* Don't fork on daemon mode. */
            ForeGroundMode = true;
            break;
        case 'i': /* Initial command. */
            PushedBack = xstrdup(optarg);
            break;
        case 'I': /* Instance. */
            NNRPinstance = xstrdup(optarg);
            break;
        case 'n': /* No DNS lookups. */
            GetHostByAddr = false;
            break;
        case 'o': /* Offline posting only. */
            Offlinepost = true;
            break;
        case 'p': /* TCP port for daemon mode. */
            ListenPort = atoi(optarg);
            break;
        case 'r': /* Reject connection message. */
            Reject = xstrdup(optarg);
            break;
        case 's': /* Unused title string - just to allocate space in command
                     line to be filled by setproctitle. */
            break;
        case 't': /* Tracing. */
            Tracing = true;
            break;
#ifdef HAVE_OPENSSL
        case 'S': /* Force the negotiation of an encryption layer. */
            initialSSL = true;
            break;
#endif /* HAVE_OPENSSL */
        }
    argc -= optind;
    if (argc)
        Usage();

    /* Make other processes happier if someone is reading.  This allows other
     * processes like overchan to keep up when there are lots of readers.
     * Note that this is cumulative with nicekids. */
    if (innconf->nicennrpd != 0) {
        errno = 0;
        if (nice(innconf->nicennrpd) < 0 && errno != 0)
            syswarn("could not nice to %lu", innconf->nicennrpd);
    }

    HISTORY = concatpath(innconf->pathdb, INN_PATH_HISTORY);
    ACTIVE = concatpath(innconf->pathdb, INN_PATH_ACTIVE);
    ACTIVETIMES = concatpath(innconf->pathdb, INN_PATH_ACTIVETIMES);
    NEWSGROUPS = concatpath(innconf->pathdb, INN_PATH_NEWSGROUPS);
    if (ConfFile)
        NNRPACCESS = ConfFile;
    else
        NNRPACCESS = concatpath(innconf->pathetc, INN_PATH_NNRPACCESS);

    /* Initialize the checks to perform or not on article syntax. */
    if ((innconf->syntaxchecks != NULL)
        && (innconf->syntaxchecks->count > 0)) {
        for (j = 0; j < innconf->syntaxchecks->count; j++) {
            if (innconf->syntaxchecks->strings[j] != NULL) {
                if (strcmp(innconf->syntaxchecks->strings[j], "laxmid") == 0) {
                    laxmid = true;
                } else if (strcmp(innconf->syntaxchecks->strings[j],
                                  "no-laxmid")
                           == 0) {
                    laxmid = false;
                } else {
                    syslog(L_NOTICE,
                           "Unknown \"%s\" value in syntaxchecks "
                           "parameter in inn.conf",
                           innconf->syntaxchecks->strings[j]);
                }
            }
        }
    }

    if (DaemonMode) {
        /* Allocate an lfds array to hold the file descriptors
         * for IPv4 and/or IPv6 connections. */
        if (ListenAddr == NULL && ListenAddr6 == NULL) {
            network_innbind_all(SOCK_STREAM, ListenPort, &lfds, &lfdcount);
        } else {
            if (ListenAddr != NULL && ListenAddr6 != NULL)
                lfdcount = 2;
            else
                lfdcount = 1;
            lfds = xmalloc(lfdcount * sizeof(int));
            i = 0;
            if (ListenAddr6 != NULL) {
                lfds[i++] =
                    network_innbind_ipv6(SOCK_STREAM, ListenAddr6, ListenPort);
            }
            if (ListenAddr != NULL) {
                lfds[i] =
                    network_innbind_ipv4(SOCK_STREAM, ListenAddr, ListenPort);
            }
        }

        /* Bail if we couldn't listen on any sockets. */
        lfdokay = false;
        for (j = 0; j < lfdcount; j++) {
            if (lfds[j] < 0)
                continue;
            lfdokay = true;
        }
        if (!lfdokay)
            die("can't bind to any addresses");

        /* If started as root, switch to news uid.  Unlike other parts of INN,
         * we don't die if we can't become the news user.  As long as we're not
         * running as root, everything's fine; it's okay to write the things we
         * write as a member of the news group. */
        if (getuid() == 0) {
            ensure_news_user_grp(true, true);
        }

        /* Detach. */
        if (!ForeGroundMode) {
            if (daemon(0, 0) < 0) {
                sysdie("cannot fork: %s", strerror(errno));
            }
        }

        if (ListenPort == NNTP_PORT)
            strlcpy(buff, "nnrpd.pid", sizeof(buff));
        else
            snprintf(buff, sizeof(buff), "nnrpd-%d.pid", ListenPort);
        path = concatpath(innconf->pathrun, buff);
        pidfile = fopen(path, "w");
        free(path);
        if (pidfile == NULL) {
            syslog(L_ERROR, "cannot write %s %m", buff);
            exit(1);
        }
        fprintf(pidfile, "%lu\n", (unsigned long) getpid());
        fclose(pidfile);

        /* Set signal handle to care for dead children. */
        if (!respawn)
            xsignal(SIGCHLD, WaitChild);

        /* Arrange to toggle tracing. */
        xsignal(SIGHUP, ToggleTrace);

        setproctitle("accepting connections");

        /* Initialize the listener file descriptors set. */
        FD_ZERO(&lfdset);

        for (j = 0; j < lfdcount; j++) {
            if (listen(lfds[j], innconf->maxlisten) < 0) {
                if (j != 0 && errno == EADDRINUSE)
                    continue;
                syslog(L_ERROR, "can't listen to socket");
            } else {
                /* Remember the largest descriptor number
                 * that is to be tested by select(). */
                FD_SET(lfds[j], &lfdset);
                if (lfdmax < lfds[j])
                    lfdmax = lfds[j];
            }
        }

        if (respawn) {
            /* Pre-forked mode. */
            for (;;) {
                if (respawn > 0) {
                    --respawn;
                    pid = fork();
                    if (pid == 0) {
                        do {
                            fd = -1;

                            /* Copy the master set because lfdsetread
                             * will be modified. */
                            lfdsetread = lfdset;
                            lfdreadcount = select(lfdmax + 1, &lfdsetread,
                                                  NULL, NULL, NULL);

                            if (lfdreadcount > 0) {
                                for (j = 0; j < lfdcount; j++) {
                                    if (FD_ISSET(lfds[j], &lfdsetread)) {
                                        fd = accept(lfds[j], NULL, NULL);
                                        /* Only handle the first match.  Future
                                         * calls to select() will handle
                                         * possible other matches. */
                                        if (fd >= 0)
                                            break;
                                    }
                                }
                            }
                        } while (fd < 0);
                        break;
                    }
                }
                for (;;) {
                    if (respawn == 0)
                        pid = wait(NULL);
                    else
                        pid = waitpid(-1, NULL, WNOHANG);
                    if (pid <= 0)
                        break;
                    ++respawn;
                }
            }
        } else {
            /* Fork on demand. */
            do {
                fd = -1;

                /* Copy the master set because lfdsetread will be modified. */
                lfdsetread = lfdset;
                lfdreadcount =
                    select(lfdmax + 1, &lfdsetread, NULL, NULL, NULL);

                if (lfdreadcount > 0) {
                    for (j = 0; j < lfdcount; j++) {
                        if (FD_ISSET(lfds[j], &lfdsetread)) {
                            fd = accept(lfds[j], NULL, NULL);
                            /* Only handle the first match.  Future calls
                             * to select() will handle possible other matches.
                             */
                            if (fd >= 0)
                                break;
                        }
                    }
                }
                if (fd < 0)
                    continue;

                for (j = 0; j <= innconf->maxforks && (pid = fork()) < 0;
                     j++) {
                    if (j == innconf->maxforks) {
                        syslog(L_FATAL,
                               "can't fork (dropping connection): %m");
                        continue;
                    }
                    syslog(L_NOTICE, "can't fork (waiting): %m");
                    sleep(1);
                }
                if (ChangeTrace) {
                    Tracing = Tracing ? false : true;
                    syslog(L_TRACE, "trace %sabled", Tracing ? "en" : "dis");
                    ChangeTrace = false;
                }
                if (pid != 0)
                    close(fd);
            } while (pid != 0);
        }

        /* Child process starts here. */
        setproctitle("connected");
        for (j = 0; j < lfdcount; j++) {
            close(lfds[j]);
        }
        dup2(fd, 0);
        close(fd);
        dup2(0, 1);
        dup2(0, 2);
        if (innconf->timer != 0)
            TMRinit(TMR_MAX);
        STATstart = TMRnow_double();
        SetupDaemon();

        /* If we are a daemon, innd didn't make us nice, so be nice kids. */
        if (innconf->nicekids) {
            if (nice(innconf->nicekids) < 0)
                syslog(L_ERROR, "Could not nice child to %ld: %m",
                       innconf->nicekids);
        }

        /* Only automatically reap children in the listening process. */
        xsignal(SIGCHLD, SIG_DFL);

    } else {
        if (innconf->timer != 0)
            TMRinit(TMR_MAX);
        STATstart = TMRnow_double();
        SetupDaemon();
        /* Arrange to toggle tracing. */
        xsignal(SIGHUP, ToggleTrace);
    } /* DaemonMode */

#ifdef HAVE_OPENSSL
    if (initialSSL) {
        tls_init();
        if (tls_start_servertls(0, 1) == -1) {
            GetClientInfo(ListenPort);
            notice("%s failure to negotiate TLS session", Client.host);
            Reply("%d Encrypted TLS connection failed\r\n",
                  NNTP_FAIL_TERMINATING);
            ExitWithStats(1, false);
        }
        encryption_layer_on = true;

#    if defined(HAVE_ZLIB) && OPENSSL_VERSION_NUMBER >= 0x00090800fL
        /* Check whether a compression layer has just been added.
         * SSL_get_current_compression() is defined in OpenSSL versions >=
         * 0.9.8 final release, as well as LibreSSL. */
        tls_compression_on = (SSL_get_current_compression(tls_conn) != NULL);
        compression_layer_on = tls_compression_on;
#    endif /* HAVE_ZLIB && OPENSSL >= v0.9.8 */
    }
#endif /* HAVE_OPENSSL */

    /* If requested, check the load average. */
    if (innconf->nnrpdloadlimit != 0) {
        double load[1];

        if (getloadavg(load, 1) < 0)
            warn("cannot obtain system load");
        else {
            if ((unsigned long) (load[0] + 0.5) > innconf->nnrpdloadlimit) {
                GetClientInfo(ListenPort);
                notice("%s load %.2f > %lu", Client.host, load[0],
                       innconf->nnrpdloadlimit);
                Reply("%d load at %.2f, try later\r\n", NNTP_FAIL_TERMINATING,
                      load[0]);
                ExitWithStats(1, true);
            }
        }
    }

    /* Catch SIGPIPE so that we can exit out of long write loops. */
    xsignal(SIGPIPE, CatchPipe);

    /* Read our secrets, if available.
     * Even if we fail reading them, we can just go on.  Don't bail out, the
     * related features will just not be activated.
     * The file is read by each nnrpd newly spawned. */
    secrets_read(NULL);

    /* Get permissions and see if we can talk to this client. */
    GetClientInfo(ListenPort);
    PERMgetinitialaccess(NNRPACCESS);
    PERMgetaccess(true);
    PERMgetpermissions();

    if (!PERMcanread && !PERMcanpost && !PERMneedauth) {
        syslog(L_NOTICE, "%s no_permission", Client.host);
        Reply("%d You have no permission to talk.  Goodbye!\r\n",
              NNTP_ERR_ACCESS);
        ExitWithStats(1, false);
    }

    /* Proceed with initialization. */
    setproctitle("%s connect", Client.host);

    /* Were we told to reject connections? */
    if (Reject) {
        syslog(L_NOTICE, "%s rejected %s", Client.host, Reject);
        Reply("%d %s\r\n", NNTP_FAIL_TERMINATING,
              is_valid_utf8(Reject) ? Reject : "Connection rejected");
        ExitWithStats(0, false);
    }

    if (PERMaccessconf) {
        if (PERMaccessconf->readertrack)
            PERMaccessconf->readertrack =
                TrackClient(Client.host, Username, sizeof(Username));
    } else {
        if (innconf->readertrack)
            innconf->readertrack =
                TrackClient(Client.host, Username, sizeof(Username));
    }

    if ((PERMaccessconf && PERMaccessconf->readertrack)
        || (!PERMaccessconf && innconf->readertrack)) {
        int len;
        syslog(L_NOTICE, "%s Tracking Enabled (%s)", Client.host, Username);
        pid = getpid();
        gettimeofday(&tv, NULL);
        count += pid;
        vid = tv.tv_sec ^ tv.tv_usec ^ pid ^ count;
        len = strlen("innconf->pathlog") + strlen("/tracklogs/log-") + BUFSIZ;
        LocalLogFileName = xmalloc(len);
        sprintf(LocalLogFileName, "%s/tracklogs/log-%u", innconf->pathlog,
                vid);
        if ((locallog = fopen(LocalLogFileName, "w")) == NULL) {
            LocalLogDirName = concatpath(innconf->pathlog, "tracklogs");
            MakeDirectory(LocalLogDirName, false);
            free(LocalLogDirName);
        }
        if (locallog == NULL
            && (locallog = fopen(LocalLogFileName, "w")) == NULL) {
            syslog(L_ERROR, "%s Local Logging failed (%s) %s: %m", Client.host,
                   Username, LocalLogFileName);
        } else {
            syslog(L_NOTICE, "%s Local Logging begins (%s) %s", Client.host,
                   Username, LocalLogFileName);
            fprintf(locallog, "%s Tracking Enabled (%s)\n", Client.host,
                    Username);
            fflush(locallog);
            LLOGenable = true;
        }
    }

#ifdef HAVE_SASL
    SASLnewserver();
#endif /* HAVE_SASL */

    if (PERMaccessconf) {
        Reply("%d %s InterNetNews NNRP server %s ready (%s)\r\n",
              (PERMcanpost || (PERMcanauthenticate && PERMcanpostgreeting))
                  ? NNTP_OK_BANNER_POST
                  : NNTP_OK_BANNER_NOPOST,
              PERMaccessconf->pathhost, INN_VERSION_STRING,
              (!PERMneedauth && PERMcanpost) ? "posting ok" : "no posting");
        clienttimeout = PERMaccessconf->clienttimeout;
    } else {
        Reply("%d %s InterNetNews NNRP server %s ready (%s)\r\n",
              (PERMcanpost || (PERMcanauthenticate && PERMcanpostgreeting))
                  ? NNTP_OK_BANNER_POST
                  : NNTP_OK_BANNER_NOPOST,
              innconf->pathhost, INN_VERSION_STRING,
              (!PERMneedauth && PERMcanpost) ? "posting ok" : "no posting");
        clienttimeout = innconf->clienttimeout;
    }

    line_init(&NNTPline);

    /* Main dispatch loop. */
    for (timeout = innconf->initialtimeout, av = NULL, ac = 0;;
         timeout = clienttimeout) {
        TMRstart(TMR_NNTPWRITE);
        fflush(stdout);
        TMRstop(TMR_NNTPWRITE);
        if (ChangeTrace) {
            Tracing = Tracing ? false : true;
            syslog(L_TRACE, "trace %sabled", Tracing ? "en" : "dis");
            ChangeTrace = false;
        }
        if (PushedBack) {
            if (PushedBack[0] == '\0')
                continue;
            if (Tracing)
                syslog(L_TRACE, "%s < %s", Client.host, PushedBack);
            ac = nArgify(PushedBack, &av, 1);
            r = RTok;
        } else {
            size_t len;
            size_t lenstripped = 0;
            const char *p;
            char *q;

            r = line_read(&NNTPline, timeout, &p, &len, &lenstripped);
            switch (r) {
            default:
                syslog(L_ERROR, "%s internal %u in main", Client.host, r);
                goto fallthroughRTtimeout;
            case RTtimeout:
            fallthroughRTtimeout:
                if (timeout < clienttimeout)
                    syslog(L_NOTICE, "%s timeout short", Client.host);
                else
                    syslog(L_NOTICE, "%s timeout", Client.host);
                ExitWithStats(1, false);
                /* NOTREACHED */
            case RTok:
                /* len does not count CRLF. */
                if (len + lenstripped <= sizeof(buff)) {
                    /* line_read guarantees null termination. */
                    memcpy(buff, p, len + 1);
                    /* Do some input processing, check for blank line. */
                    if (buff[0] != '\0')
                        ac = nArgify(buff, &av, 1);
                    if (Tracing) {
                        /* Do not log passwords if AUTHINFO PASS,
                         * AUTHINFO SASL PLAIN or AUTHINFO SASL EXTERNAL
                         * are used.  (Only one space between SASL and
                         * PLAIN/EXTERNAL should be put; otherwise, the
                         * whole command will be logged).
                         * AUTHINFO SASL LOGIN does not use an initial
                         * response;
                         * therefore, there is nothing to hide here. */
                        if (ac > 1 && strcasecmp(av[0], "AUTHINFO") == 0) {
                            if (strncasecmp(av[1], "PASS", 4) == 0)
                                syslog(L_TRACE, "%s < AUTHINFO PASS ********",
                                       Client.host);
                            else if (strncasecmp(av[1], "SASL PLAIN", 10) == 0)
                                syslog(L_TRACE,
                                       "%s < AUTHINFO SASL PLAIN ********",
                                       Client.host);
                            else if (strncasecmp(av[1], "SASL EXTERNAL", 13)
                                     == 0)
                                syslog(L_TRACE,
                                       "%s < AUTHINFO SASL EXTERNAL ********",
                                       Client.host);
                            else
                                syslog(L_TRACE, "%s < %s", Client.host, buff);
                        } else {
                            syslog(L_TRACE, "%s < %s", Client.host, buff);
                        }
                    }
                    if (buff[0] == '\0')
                        continue;
                    break;
                }
                goto fallthroughRTlong;
            case RTlong:
            fallthroughRTlong:
                /* The line is too long but we have to make sure that
                 * no recognized command has been sent. */
                q = (char *) p;
                ac = nArgify(q, &av, 1);
                validcommandtoolong = false;
                for (cp = CMDtable; cp->Name; cp++) {
                    if ((cp->Function != CMD_unimp)
                        && (ac > 0 && strcasecmp(cp->Name, av[0]) == 0)) {
                        validcommandtoolong = true;
                        break;
                    }
                }
                Reply("%d Line too long\r\n", validcommandtoolong
                                                  ? NNTP_ERR_SYNTAX
                                                  : NNTP_ERR_COMMAND);
                continue;
            case RTeof:
                /* Handled below. */
                break;
            }
        }
        /* Client gone? */
        if (r == RTeof)
            break;
        if (ac == 0)
            continue;

        /* Find command. */
        for (cp = CMDtable; cp->Name; cp++)
            if (strcasecmp(cp->Name, av[0]) == 0)
                break;

        /* If no command has been recognized. */
        if (cp->Name == NULL) {
            if (strcasecmp(av[0], "XYZZY") == 0) {
                /* Acknowledge the magic word from the Colossal Cave Adventure
                 * computer game. */
                Reply("%d Nothing happens\r\n", NNTP_ERR_COMMAND);
            } else if (strcasecmp(av[0], "MAXARTNUM") == 0) {
                Reply("%d Wish I could be taught to count beyond %lu\r\n",
                      NNTP_ERR_COMMAND, NNTP_MAXARTNUM);
            } else {
                Reply("%d What?\r\n", NNTP_ERR_COMMAND);
                if ((int) strlen(buff) > 40)
                    syslog(L_NOTICE, "%s unrecognized %.40s...", Client.host,
                           buff);
                else
                    syslog(L_NOTICE, "%s unrecognized %s", Client.host, buff);
            }
            continue;
        }

        /* Go on parsing the command. */
        ac--;
        ac += reArgify(av[ac], &av[ac],
                       cp->Stripspaces ? -1 : cp->Minac - ac - 1,
                       cp->Stripspaces);

        /* Check whether all arguments do not exceed their allowed size. */
        if (ac > 1) {
            validcommandtoolong = false;
            for (v = av; *v; v++)
                if (strlen(*v) > NNTP_MAXLEN_ARG) {
                    validcommandtoolong = true;
                    Reply("%d Argument too long\r\n", NNTP_ERR_SYNTAX);
                    break;
                }
            if (validcommandtoolong)
                continue;
        }

        /* Check usage. */
        if ((cp->Minac != CMDany && ac < cp->Minac)
            || (cp->Maxac != CMDany && ac > cp->Maxac)) {
            Reply("%d Syntax is: %s %s\r\n", NNTP_ERR_SYNTAX, cp->Name,
                  cp->Help ? cp->Help : "(no argument allowed)");
            continue;
        }

        /* Check permissions and dispatch. */
        if (cp->Needauth && PERMneedauth) {
            Reply("%d Authentication required for command\r\n",
                  NNTP_FAIL_AUTH_NEEDED);
            continue;
        }
        setproctitle("%s %s", Client.host, av[0]);

        (*cp->Function)(ac, av);

        if (PushedBack)
            break;
        if (PERMaccessconf)
            clienttimeout = PERMaccessconf->clienttimeout;
        else
            clienttimeout = innconf->clienttimeout;
    }

    ExitWithStats(0, false);

    /* NOTREACHED */
    return 1;
}
