[irc/freenode/solanum.git] / ircd / s_serv.c

/*
 *  ircd-ratbox: A slightly useful ircd.
 *  s_serv.c: Server related functions.
 *
 *  Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
 *  Copyright (C) 1996-2002 Hybrid Development Team
 *  Copyright (C) 2002-2005 ircd-ratbox development team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *  USA
 */

#include "stdinc.h"

#ifdef HAVE_LIBCRYPTO
#include <openssl/rsa.h>
#endif

#include "s_serv.h"
#include "class.h"
#include "client.h"
#include "hash.h"
#include "match.h"
#include "ircd.h"
#include "ircd_defs.h"
#include "numeric.h"
#include "packet.h"
#include "s_conf.h"
#include "s_newconf.h"
#include "logger.h"
#include "s_stats.h"
#include "s_user.h"
#include "scache.h"
#include "send.h"
#include "client.h"
#include "channel.h"            /* chcap_usage_counts stuff... */
#include "hook.h"
#include "msg.h"
#include "reject.h"
#include "sslproc.h"
#include "capability.h"
#include "s_assert.h"

int MaxConnectionCount = 1;
int MaxClientCount = 1;
int refresh_user_links = 0;

static char buf[BUFSIZE];

/*
 * list of recognized server capabilities.  "TS" is not on the list
 * because all servers that we talk to already do TS, and the kludged
 * extra argument to "PASS" takes care of checking that.  -orabidoo
 */
struct CapabilityIndex *serv_capindex = NULL;
struct CapabilityIndex *cli_capindex = NULL;

unsigned int CAP_CAP;
unsigned int CAP_QS;
unsigned int CAP_EX;
unsigned int CAP_CHW;
unsigned int CAP_IE;
unsigned int CAP_KLN;
unsigned int CAP_ZIP;
unsigned int CAP_KNOCK;
unsigned int CAP_TB;
unsigned int CAP_UNKLN;
unsigned int CAP_CLUSTER;
unsigned int CAP_ENCAP;
unsigned int CAP_TS6;
unsigned int CAP_SERVICE;
unsigned int CAP_RSFNC;
unsigned int CAP_SAVE;
unsigned int CAP_EUID;
unsigned int CAP_EOPMOD;
unsigned int CAP_BAN;
unsigned int CAP_MLOCK;

unsigned int CLICAP_MULTI_PREFIX;
unsigned int CLICAP_ACCOUNT_NOTIFY;
unsigned int CLICAP_EXTENDED_JOIN;
unsigned int CLICAP_AWAY_NOTIFY;
unsigned int CLICAP_USERHOST_IN_NAMES;
unsigned int CLICAP_CAP_NOTIFY;
unsigned int CLICAP_CHGHOST;
unsigned int CLICAP_ECHO_MESSAGE;

/*
 * initialize our builtin capability table. --nenolod
 */
void
init_builtin_capabs(void)
{
        static struct ClientCapability high_priority = {.flags = CLICAP_FLAGS_PRIORITY};
        serv_capindex = capability_index_create("server capabilities");

        /* These two are not set via CAPAB/GCAP keywords. */
        CAP_CAP = capability_put_anonymous(serv_capindex);
        CAP_TS6 = capability_put_anonymous(serv_capindex);

        CAP_QS = capability_put(serv_capindex, "QS", NULL);
        CAP_EX = capability_put(serv_capindex, "EX", NULL);
        CAP_CHW = capability_put(serv_capindex, "CHW", NULL);
        CAP_IE = capability_put(serv_capindex, "IE", NULL);
        CAP_KLN = capability_put(serv_capindex, "KLN", NULL);
        CAP_KNOCK = capability_put(serv_capindex, "KNOCK", NULL);
        CAP_ZIP = capability_put(serv_capindex, "ZIP", NULL);
        CAP_TB = capability_put(serv_capindex, "TB", NULL);
        CAP_UNKLN = capability_put(serv_capindex, "UNKLN", NULL);
        CAP_CLUSTER = capability_put(serv_capindex, "CLUSTER", NULL);
        CAP_ENCAP = capability_put(serv_capindex, "ENCAP", NULL);
        CAP_SERVICE = capability_put(serv_capindex, "SERVICES", NULL);
        CAP_RSFNC = capability_put(serv_capindex, "RSFNC", NULL);
        CAP_SAVE = capability_put(serv_capindex, "SAVE", NULL);
        CAP_EUID = capability_put(serv_capindex, "EUID", NULL);
        CAP_EOPMOD = capability_put(serv_capindex, "EOPMOD", NULL);
        CAP_BAN = capability_put(serv_capindex, "BAN", NULL);
        CAP_MLOCK = capability_put(serv_capindex, "MLOCK", NULL);

        capability_require(serv_capindex, "QS");
        capability_require(serv_capindex, "EX");
        capability_require(serv_capindex, "IE");
        capability_require(serv_capindex, "ENCAP");

        cli_capindex = capability_index_create("client capabilities");

        CLICAP_MULTI_PREFIX = capability_put(cli_capindex, "multi-prefix", &high_priority);
        CLICAP_ACCOUNT_NOTIFY = capability_put(cli_capindex, "account-notify", &high_priority);
        CLICAP_EXTENDED_JOIN = capability_put(cli_capindex, "extended-join", &high_priority);
        CLICAP_AWAY_NOTIFY = capability_put(cli_capindex, "away-notify", &high_priority);
        CLICAP_USERHOST_IN_NAMES = capability_put(cli_capindex, "userhost-in-names", &high_priority);
        CLICAP_CAP_NOTIFY = capability_put(cli_capindex, "cap-notify", NULL);
        CLICAP_CHGHOST = capability_put(cli_capindex, "chghost", &high_priority);
        CLICAP_ECHO_MESSAGE = capability_put(cli_capindex, "echo-message", NULL);
}

static CNCB serv_connect_callback;
static CNCB serv_connect_ssl_callback;
static SSL_OPEN_CB serv_connect_ssl_open_callback;

/*
 * hunt_server - Do the basic thing in delivering the message (command)
 *      across the relays to the specific server (server) for
 *      actions.
 *
 *      Note:   The command is a format string and *MUST* be
 *              of prefixed style (e.g. ":%s COMMAND %s ...").
 *              Command can have only max 8 parameters.
 *
 *      server  parv[server] is the parameter identifying the
 *              target server.
 *
 *      *WARNING*
 *              parv[server] is replaced with the pointer to the
 *              real servername from the matched client (I'm lazy
 *              now --msa).
 *
 *      returns: (see #defines)
 */
int
hunt_server(struct Client *client_p, struct Client *source_p,
            const char *command, int server, int parc, const char *parv[])
{
        struct Client *target_p;
        int wilds;
        rb_dlink_node *ptr;
        const char *old;
        char *new;

        /*
         * Assume it's me, if no server
         */
        if(parc <= server || EmptyString(parv[server]) ||
           match(parv[server], me.name) || (strcmp(parv[server], me.id) == 0))
                return (HUNTED_ISME);

        new = LOCAL_COPY(parv[server]);

        /*
         * These are to pickup matches that would cause the following
         * message to go in the wrong direction while doing quick fast
         * non-matching lookups.
         */
        if(MyClient(source_p))
                target_p = find_named_client(new);
        else
                target_p = find_client(new);

        if(target_p)
                if(target_p->from == source_p->from && !MyConnect(target_p))
                        target_p = NULL;

        collapse(new);
        wilds = (strchr(new, '?') || strchr(new, '*'));

        /*
         * Again, if there are no wild cards involved in the server
         * name, use the hash lookup
         */
        if(!target_p && wilds)
        {
                RB_DLINK_FOREACH(ptr, global_serv_list.head)
                {
                        if(match(new, ((struct Client *) (ptr->data))->name))
                        {
                                target_p = ptr->data;
                                break;
                        }
                }
        }

        if(target_p && !IsRegistered(target_p))
                target_p = NULL;

        if(target_p)
        {
                if(IsMe(target_p) || MyClient(target_p))
                        return HUNTED_ISME;

                old = parv[server];
                parv[server] = get_id(target_p, target_p);

                sendto_one(target_p, command, get_id(source_p, target_p),
                           parv[1], parv[2], parv[3], parv[4], parv[5], parv[6], parv[7], parv[8]);
                parv[server] = old;
                return (HUNTED_PASS);
        }

        if(MyClient(source_p) || !IsDigit(parv[server][0]))
                sendto_one_numeric(source_p, ERR_NOSUCHSERVER,
                                   form_str(ERR_NOSUCHSERVER), parv[server]);
        return (HUNTED_NOSUCH);
}

/*
 * try_connections - scan through configuration and try new connections.
 * Returns the calendar time when the next call to this
 * function should be made latest. (No harm done if this
 * is called earlier or later...)
 */
void
try_connections(void *unused)
{
        struct Client *client_p;
        struct server_conf *server_p = NULL;
        struct server_conf *tmp_p;
        struct Class *cltmp;
        rb_dlink_node *ptr;
        bool connecting = false;
        int confrq = 0;
        time_t next = 0;

        RB_DLINK_FOREACH(ptr, server_conf_list.head)
        {
                tmp_p = ptr->data;

                if(ServerConfIllegal(tmp_p) || !ServerConfAutoconn(tmp_p))
                        continue;

                /* don't allow ssl connections if ssl isn't setup */
                if(ServerConfSSL(tmp_p) && (!ircd_ssl_ok || !get_ssld_count()))
                        continue;

                cltmp = tmp_p->class;

                /*
                 * Skip this entry if the use of it is still on hold until
                 * future. Otherwise handle this entry (and set it on hold
                 * until next time). Will reset only hold times, if already
                 * made one successfull connection... [this algorithm is
                 * a bit fuzzy... -- msa >;) ]
                 */
                if(tmp_p->hold > rb_current_time())
                {
                        if(next > tmp_p->hold || next == 0)
                                next = tmp_p->hold;
                        continue;
                }

                confrq = get_con_freq(cltmp);
                tmp_p->hold = rb_current_time() + confrq;

                /*
                 * Found a CONNECT config with port specified, scan clients
                 * and see if this server is already connected?
                 */
                client_p = find_server(NULL, tmp_p->name);

                if(!client_p && (CurrUsers(cltmp) < MaxAutoconn(cltmp)) && !connecting)
                {
                        server_p = tmp_p;

                        /* We connect only one at time... */
                        connecting = true;
                }

                if((next > tmp_p->hold) || (next == 0))
                        next = tmp_p->hold;
        }

        /* TODO: change this to set active flag to 0 when added to event! --Habeeb */
        if(GlobalSetOptions.autoconn == 0)
                return;

        if(!connecting)
                return;

        /* move this connect entry to end.. */
        rb_dlinkDelete(&server_p->node, &server_conf_list);
        rb_dlinkAddTail(server_p, &server_p->node, &server_conf_list);

        /*
         * We used to only print this if serv_connect() actually
         * suceeded, but since rb_tcp_connect() can call the callback
         * immediately if there is an error, we were getting error messages
         * in the wrong order. SO, we just print out the activated line,
         * and let serv_connect() / serv_connect_callback() print an
         * error afterwards if it fails.
         *   -- adrian
         */
        sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                        "Connection to %s activated",
                        server_p->name);

        serv_connect(server_p, 0);
}

int
check_server(const char *name, struct Client *client_p)
{
        struct server_conf *server_p = NULL;
        struct server_conf *tmp_p;
        rb_dlink_node *ptr;
        int error = -1;
        const char *encr;
        bool name_matched = false;
        bool host_matched = false;
        bool certfp_failed = false;

        s_assert(NULL != client_p);
        if(client_p == NULL)
                return error;

        if(!(client_p->localClient->passwd))
                return -2;

        if(strlen(name) > HOSTLEN)
                return -4;

        RB_DLINK_FOREACH(ptr, server_conf_list.head)
        {
                struct rb_sockaddr_storage client_addr;

                tmp_p = ptr->data;

                if(ServerConfIllegal(tmp_p))
                        continue;

                if(!match(tmp_p->name, name))
                        continue;

                name_matched = true;

                if(rb_inet_pton_sock(client_p->sockhost, &client_addr) <= 0)
                        SET_SS_FAMILY(&client_addr, AF_UNSPEC);

                if((tmp_p->connect_host && match(tmp_p->connect_host, client_p->host))
                        || (GET_SS_FAMILY(&client_addr) == GET_SS_FAMILY(&tmp_p->connect4)
                                && comp_with_mask_sock((struct sockaddr *)&client_addr,
                                        (struct sockaddr *)&tmp_p->connect4, 32))
                        || (GET_SS_FAMILY(&client_addr) == GET_SS_FAMILY(&tmp_p->connect6)
                                && comp_with_mask_sock((struct sockaddr *)&client_addr,
                                        (struct sockaddr *)&tmp_p->connect6, 128))
                        )
                {
                        host_matched = true;

                        if(tmp_p->passwd)
                        {
                                if(ServerConfEncrypted(tmp_p))
                                {
                                        encr = rb_crypt(client_p->localClient->passwd,
                                                                        tmp_p->passwd);
                                        if(encr != NULL && !strcmp(tmp_p->passwd, encr))
                                        {
                                                server_p = tmp_p;
                                                break;
                                        }
                                        else
                                                continue;
                                }
                                else if(strcmp(tmp_p->passwd, client_p->localClient->passwd))
                                        continue;
                        }

                        if(tmp_p->certfp)
                        {
                                if(!client_p->certfp || rb_strcasecmp(tmp_p->certfp, client_p->certfp) != 0) {
                                        certfp_failed = true;
                                        continue;
                                }
                        }

                        server_p = tmp_p;
                        break;
                }
        }

        if(server_p == NULL)
        {
                /* return the most specific error */
                if(certfp_failed)
                        error = -6;
                else if(host_matched)
                        error = -2;
                else if(name_matched)
                        error = -3;

                return error;
        }

        if(ServerConfSSL(server_p) && client_p->localClient->ssl_ctl == NULL)
        {
                return -5;
        }

        if (client_p->localClient->att_sconf && client_p->localClient->att_sconf->class == server_p->class) {
                /* this is an outgoing connection that is already attached to the correct class */
        } else if (CurrUsers(server_p->class) >= MaxUsers(server_p->class)) {
                return -7;
        }
        attach_server_conf(client_p, server_p);

        /* clear ZIP/TB if they support but we dont want them */
#ifdef HAVE_LIBZ
        if(!ServerConfCompressed(server_p))
#endif
                ClearCap(client_p, CAP_ZIP);

        if(!ServerConfTb(server_p))
                ClearCap(client_p, CAP_TB);

        return 0;
}

/*
 * send_capabilities
 *
 * inputs       - Client pointer to send to
 *              - int flag of capabilities that this server has
 * output       - NONE
 * side effects - send the CAPAB line to a server  -orabidoo
 */
void
send_capabilities(struct Client *client_p, unsigned int cap_can_send)
{
        sendto_one(client_p, "CAPAB :%s", capability_index_list(serv_capindex, cap_can_send));
}

static void
burst_ban(struct Client *client_p)
{
        rb_dlink_node *ptr;
        struct ConfItem *aconf;
        const char *type, *oper;
        /* +5 for !,@,{,} and null */
        char operbuf[NICKLEN + USERLEN + HOSTLEN + HOSTLEN + 5];
        char *p;
        size_t melen;

        melen = strlen(me.name);
        RB_DLINK_FOREACH(ptr, prop_bans.head)
        {
                aconf = ptr->data;

                /* Skip expired stuff. */
                if(aconf->lifetime < rb_current_time())
                        continue;
                switch(aconf->status & ~CONF_ILLEGAL)
                {
                        case CONF_KILL: type = "K"; break;
                        case CONF_DLINE: type = "D"; break;
                        case CONF_XLINE: type = "X"; break;
                        case CONF_RESV_NICK: type = "R"; break;
                        case CONF_RESV_CHANNEL: type = "R"; break;
                        default:
                                continue;
                }
                oper = aconf->info.oper;
                if(aconf->flags & CONF_FLAGS_MYOPER)
                {
                        /* Our operator{} names may not be meaningful
                         * to other servers, so rewrite to our server
                         * name.
                         */
                        rb_strlcpy(operbuf, aconf->info.oper, sizeof operbuf);
                        p = strrchr(operbuf, '{');
                        if (p != NULL &&
                                        operbuf + sizeof operbuf - p > (ptrdiff_t)(melen + 2))
                        {
                                memcpy(p + 1, me.name, melen);
                                p[melen + 1] = '}';
                                p[melen + 2] = '\0';
                                oper = operbuf;
                        }
                }
                sendto_one(client_p, ":%s BAN %s %s %s %lu %d %d %s :%s%s%s",
                                me.id,
                                type,
                                aconf->user ? aconf->user : "*", aconf->host,
                                (unsigned long)aconf->created,
                                (int)(aconf->hold - aconf->created),
                                (int)(aconf->lifetime - aconf->created),
                                oper,
                                aconf->passwd,
                                aconf->spasswd ? "|" : "",
                                aconf->spasswd ? aconf->spasswd : "");
        }
}

/* burst_modes_TS6()
 *
 * input        - client to burst to, channel name, list to burst, mode flag
 * output       -
 * side effects - client is sent a list of +b, +e, or +I modes
 */
static void
burst_modes_TS6(struct Client *client_p, struct Channel *chptr,
                rb_dlink_list *list, char flag)
{
        rb_dlink_node *ptr;
        struct Ban *banptr;

        send_multiline_init(client_p, " ", ":%s BMASK %ld %s %c :",
                        me.id,
                        (long)chptr->channelts,
                        chptr->chname,
                        flag);

        RB_DLINK_FOREACH_PREV(ptr, list->tail)
        {
                banptr = ptr->data;

                if (banptr->forward)
                        send_multiline_item(client_p, "%s$%s",
                                        banptr->banstr,
                                        banptr->forward);
                else
                        send_multiline_item(client_p, "%s", banptr->banstr);
        }

        send_multiline_fini(client_p, NULL);
}

/*
 * burst_TS6
 *
 * inputs       - client (server) to send nick towards
 *              - client to send nick for
 * output       - NONE
 * side effects - NICK message is sent towards given client_p
 */
static void
burst_TS6(struct Client *client_p)
{
        char ubuf[BUFSIZE];
        struct Client *target_p;
        struct Channel *chptr;
        struct membership *msptr;
        hook_data_client hclientinfo;
        hook_data_channel hchaninfo;
        rb_dlink_node *ptr;
        rb_dlink_node *uptr;
        char *t;
        int tlen, mlen;
        int cur_len = 0;

        hclientinfo.client = hchaninfo.client = client_p;

        RB_DLINK_FOREACH(ptr, global_client_list.head)
        {
                target_p = ptr->data;

                if(!IsPerson(target_p))
                        continue;

                if(MyClient(target_p->from) && target_p->localClient->att_sconf != NULL && ServerConfNoExport(target_p->localClient->att_sconf))
                        continue;

                send_umode(NULL, target_p, 0, ubuf);
                if(!*ubuf)
                {
                        ubuf[0] = '+';
                        ubuf[1] = '\0';
                }

                if(IsCapable(client_p, CAP_EUID))
                        sendto_one(client_p, ":%s EUID %s %d %ld %s %s %s %s %s %s %s :%s",
                                   target_p->servptr->id, target_p->name,
                                   target_p->hopcount + 1,
                                   (long) target_p->tsinfo, ubuf,
                                   target_p->username, target_p->host,
                                   IsIPSpoof(target_p) ? "0" : target_p->sockhost,
                                   target_p->id,
                                   IsDynSpoof(target_p) ? target_p->orighost : "*",
                                   EmptyString(target_p->user->suser) ? "*" : target_p->user->suser,
                                   target_p->info);
                else
                        sendto_one(client_p, ":%s UID %s %d %ld %s %s %s %s %s :%s",
                                   target_p->servptr->id, target_p->name,
                                   target_p->hopcount + 1,
                                   (long) target_p->tsinfo, ubuf,
                                   target_p->username, target_p->host,
                                   IsIPSpoof(target_p) ? "0" : target_p->sockhost,
                                   target_p->id, target_p->info);

                if(!EmptyString(target_p->certfp))
                        sendto_one(client_p, ":%s ENCAP * CERTFP :%s",
                                        use_id(target_p), target_p->certfp);

                if(!IsCapable(client_p, CAP_EUID))
                {
                        if(IsDynSpoof(target_p))
                                sendto_one(client_p, ":%s ENCAP * REALHOST %s",
                                                use_id(target_p), target_p->orighost);
                        if(!EmptyString(target_p->user->suser))
                                sendto_one(client_p, ":%s ENCAP * LOGIN %s",
                                                use_id(target_p), target_p->user->suser);
                }

                if(ConfigFileEntry.burst_away && !EmptyString(target_p->user->away))
                        sendto_one(client_p, ":%s AWAY :%s",
                                   use_id(target_p),
                                   target_p->user->away);

                if(IsOper(target_p) && target_p->user && target_p->user->opername && target_p->user->privset)
                        sendto_one(client_p, ":%s OPER %s %s",
                                        use_id(target_p),
                                        target_p->user->opername,
                                        target_p->user->privset->name);

                hclientinfo.target = target_p;
                call_hook(h_burst_client, &hclientinfo);
        }

        RB_DLINK_FOREACH(ptr, global_channel_list.head)
        {
                chptr = ptr->data;

                if(*chptr->chname != '#')
                        continue;

                cur_len = mlen = sprintf(buf, ":%s SJOIN %ld %s %s :", me.id,
                                (long) chptr->channelts, chptr->chname,
                                channel_modes(chptr, client_p));

                t = buf + mlen;

                RB_DLINK_FOREACH(uptr, chptr->members.head)
                {
                        msptr = uptr->data;

                        tlen = strlen(use_id(msptr->client_p)) + 1;
                        if(is_chanop(msptr))
                                tlen++;
                        if(is_voiced(msptr))
                                tlen++;

                        if(cur_len + tlen >= BUFSIZE - 3)
                        {
                                *(t-1) = '\0';
                                sendto_one(client_p, "%s", buf);
                                cur_len = mlen;
                                t = buf + mlen;
                        }

                        sprintf(t, "%s%s ", find_channel_status(msptr, 1),
                                   use_id(msptr->client_p));

                        cur_len += tlen;
                        t += tlen;
                }

                if (rb_dlink_list_length(&chptr->members) > 0)
                {
                        /* remove trailing space */
                        *(t-1) = '\0';
                }
                sendto_one(client_p, "%s", buf);

                if(rb_dlink_list_length(&chptr->banlist) > 0)
                        burst_modes_TS6(client_p, chptr, &chptr->banlist, 'b');

                if(IsCapable(client_p, CAP_EX) &&
                   rb_dlink_list_length(&chptr->exceptlist) > 0)
                        burst_modes_TS6(client_p, chptr, &chptr->exceptlist, 'e');

                if(IsCapable(client_p, CAP_IE) &&
                   rb_dlink_list_length(&chptr->invexlist) > 0)
                        burst_modes_TS6(client_p, chptr, &chptr->invexlist, 'I');

                if(rb_dlink_list_length(&chptr->quietlist) > 0)
                        burst_modes_TS6(client_p, chptr, &chptr->quietlist, 'q');

                if(IsCapable(client_p, CAP_TB) && chptr->topic != NULL)
                        sendto_one(client_p, ":%s TB %s %ld %s%s:%s",
                                   me.id, chptr->chname, (long) chptr->topic_time,
                                   ConfigChannel.burst_topicwho ? chptr->topic_info : "",
                                   ConfigChannel.burst_topicwho ? " " : "",
                                   chptr->topic);

                if(IsCapable(client_p, CAP_MLOCK))
                        sendto_one(client_p, ":%s MLOCK %ld %s :%s",
                                   me.id, (long) chptr->channelts, chptr->chname,
                                   EmptyString(chptr->mode_lock) ? "" : chptr->mode_lock);

                hchaninfo.chptr = chptr;
                call_hook(h_burst_channel, &hchaninfo);
        }

        hclientinfo.target = NULL;
        call_hook(h_burst_finished, &hclientinfo);
}

/*
 * show_capabilities - show current server capabilities
 *
 * inputs       - pointer to an struct Client
 * output       - pointer to static string
 * side effects - build up string representing capabilities of server listed
 */
const char *
show_capabilities(struct Client *target_p)
{
        static char msgbuf[BUFSIZE];

        *msgbuf = '\0';

        if(has_id(target_p))
                rb_strlcpy(msgbuf, " TS6", sizeof(msgbuf));

        if(IsSSL(target_p))
                rb_strlcat(msgbuf, " SSL", sizeof(msgbuf));

        if(!IsServer(target_p) || !target_p->serv->caps)        /* short circuit if no caps */
                return msgbuf + 1;

        rb_strlcat(msgbuf, " ", sizeof(msgbuf));
        rb_strlcat(msgbuf, capability_index_list(serv_capindex, target_p->serv->caps), sizeof(msgbuf));

        return msgbuf + 1;
}

/*
 * server_estab
 *
 * inputs       - pointer to a struct Client
 * output       -
 * side effects -
 */
int
server_estab(struct Client *client_p)
{
        struct Client *target_p;
        struct server_conf *server_p;
        hook_data_client hdata;
        char *host;
        rb_dlink_node *ptr;
        char note[HOSTLEN + 15];

        s_assert(NULL != client_p);
        if(client_p == NULL)
                return -1;

        host = client_p->name;

        if((server_p = client_p->localClient->att_sconf) == NULL)
        {
                /* This shouldn't happen, better tell the ops... -A1kmm */
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                     "Warning: Lost connect{} block for server %s!", host);
                return exit_client(client_p, client_p, client_p, "Lost connect{} block!");
        }

        /* We shouldn't have to check this, it should already done before
         * server_estab is called. -A1kmm
         */
        if(client_p->localClient->passwd)
        {
                memset(client_p->localClient->passwd, 0, strlen(client_p->localClient->passwd));
                rb_free(client_p->localClient->passwd);
                client_p->localClient->passwd = NULL;
        }

        /* Its got identd , since its a server */
        SetGotId(client_p);

        if(IsUnknown(client_p))
        {
                /* the server may be linking based on certificate fingerprint now. --nenolod */
                sendto_one(client_p, "PASS %s TS %d :%s",
                           EmptyString(server_p->spasswd) ? "*" : server_p->spasswd, TS_CURRENT, me.id);

                /* pass info to new server */
                send_capabilities(client_p, default_server_capabs | CAP_MASK
                                  | (ServerConfCompressed(server_p) ? CAP_ZIP_SUPPORTED : 0)
                                  | (ServerConfTb(server_p) ? CAP_TB : 0));

                sendto_one(client_p, "SERVER %s 1 :%s%s",
                           me.name,
                           ConfigServerHide.hidden ? "(H) " : "",
                           (me.info[0]) ? (me.info) : "IRCers United");
        }

        if(!rb_set_buffers(client_p->localClient->F, READBUF_SIZE))
                ilog_error("rb_set_buffers failed for server");

        /* Enable compression now */
        if(IsCapable(client_p, CAP_ZIP))
        {
                start_zlib_session(client_p);
        }

        client_p->servptr = &me;

        if(IsAnyDead(client_p))
                return CLIENT_EXITED;

        sendto_one(client_p, "SVINFO %d %d 0 :%ld", TS_CURRENT, TS_MIN, (long int)rb_current_time());

        rb_dlinkAdd(client_p, &client_p->lnode, &me.serv->servers);
        rb_dlinkMoveNode(&client_p->localClient->tnode, &unknown_list, &serv_list);
        rb_dlinkAddTailAlloc(client_p, &global_serv_list);

        if(has_id(client_p))
                add_to_id_hash(client_p->id, client_p);

        add_to_client_hash(client_p->name, client_p);
        /* doesnt duplicate client_p->serv if allocated this struct already */
        make_server(client_p);
        SetServer(client_p);

        client_p->serv->caps = client_p->localClient->caps;

        if(client_p->localClient->fullcaps)
        {
                client_p->serv->fullcaps = rb_strdup(client_p->localClient->fullcaps);
                rb_free(client_p->localClient->fullcaps);
                client_p->localClient->fullcaps = NULL;
        }

        client_p->serv->nameinfo = scache_connect(client_p->name, client_p->info, IsHidden(client_p));
        client_p->localClient->firsttime = rb_current_time();
        /* fixing eob timings.. -gnp */

        if((rb_dlink_list_length(&lclient_list) + rb_dlink_list_length(&serv_list)) >
           (unsigned long)MaxConnectionCount)
                MaxConnectionCount = rb_dlink_list_length(&lclient_list) +
                                        rb_dlink_list_length(&serv_list);

        /* Show the real host/IP to admins */
        sendto_realops_snomask(SNO_GENERAL, L_ALL,
                        "Link with %s established: (%s) link",
                        client_p->name,
                        show_capabilities(client_p));

        ilog(L_SERVER, "Link with %s established: (%s) link",
             log_client_name(client_p, SHOW_IP), show_capabilities(client_p));

        hdata.client = &me;
        hdata.target = client_p;
        call_hook(h_server_introduced, &hdata);

        snprintf(note, sizeof(note), "Server: %s", client_p->name);
        rb_note(client_p->localClient->F, note);

        /*
         ** Old sendto_serv_but_one() call removed because we now
         ** need to send different names to different servers
         ** (domain name matching) Send new server to other servers.
         */
        RB_DLINK_FOREACH(ptr, serv_list.head)
        {
                target_p = ptr->data;

                if(target_p == client_p)
                        continue;

                if(target_p->localClient->att_sconf != NULL && ServerConfNoExport(target_p->localClient->att_sconf))
                        continue;

                if(has_id(target_p) && has_id(client_p))
                {
                        sendto_one(target_p, ":%s SID %s 2 %s :%s%s",
                                   me.id, client_p->name, client_p->id,
                                   IsHidden(client_p) ? "(H) " : "", client_p->info);

                        if(!EmptyString(client_p->serv->fullcaps))
                                sendto_one(target_p, ":%s ENCAP * GCAP :%s",
                                        client_p->id, client_p->serv->fullcaps);
                }
                else
                {
                        sendto_one(target_p, ":%s SERVER %s 2 :%s%s",
                                   me.name, client_p->name,
                                   IsHidden(client_p) ? "(H) " : "", client_p->info);

                        if(!EmptyString(client_p->serv->fullcaps))
                                sendto_one(target_p, ":%s ENCAP * GCAP :%s",
                                        client_p->name, client_p->serv->fullcaps);
                }
        }

        /*
         ** Pass on my client information to the new server
         **
         ** First, pass only servers (idea is that if the link gets
         ** cancelled beacause the server was already there,
         ** there are no NICK's to be cancelled...). Of course,
         ** if cancellation occurs, all this info is sent anyway,
         ** and I guess the link dies when a read is attempted...? --msa
         **
         ** Note: Link cancellation to occur at this point means
         ** that at least two servers from my fragment are building
         ** up connection this other fragment at the same time, it's
         ** a race condition, not the normal way of operation...
         **
         ** ALSO NOTE: using the get_client_name for server names--
         **    see previous *WARNING*!!! (Also, original inpath
         **    is destroyed...)
         */
        RB_DLINK_FOREACH(ptr, global_serv_list.head)
        {
                target_p = ptr->data;

                /* target_p->from == target_p for target_p == client_p */
                if(IsMe(target_p) || target_p->from == client_p)
                        continue;

                /* don't distribute downstream leaves of servers that are no-export */
                if(MyClient(target_p->from) && target_p->from->localClient->att_sconf != NULL && ServerConfNoExport(target_p->from->localClient->att_sconf))
                        continue;

                /* presumption, if target has an id, so does its uplink */
                if(has_id(client_p) && has_id(target_p))
                        sendto_one(client_p, ":%s SID %s %d %s :%s%s",
                                   target_p->servptr->id, target_p->name,
                                   target_p->hopcount + 1, target_p->id,
                                   IsHidden(target_p) ? "(H) " : "", target_p->info);
                else
                        sendto_one(client_p, ":%s SERVER %s %d :%s%s",
                                   target_p->servptr->name,
                                   target_p->name, target_p->hopcount + 1,
                                   IsHidden(target_p) ? "(H) " : "", target_p->info);

                if(!EmptyString(target_p->serv->fullcaps))
                        sendto_one(client_p, ":%s ENCAP * GCAP :%s",
                                        get_id(target_p, client_p),
                                        target_p->serv->fullcaps);
        }

        if(IsCapable(client_p, CAP_BAN))
                burst_ban(client_p);

        burst_TS6(client_p);

        /* Always send a PING after connect burst is done */
        sendto_one(client_p, "PING :%s", get_id(&me, client_p));

        free_pre_client(client_p);

        send_pop_queue(client_p);

        return 0;
}

/*
 * New server connection code
 * Based upon the stuff floating about in s_bsd.c
 *   -- adrian
 */

/*
 * serv_connect() - initiate a server connection
 *
 * inputs       - pointer to conf
 *              - pointer to client doing the connet
 * output       -
 * side effects -
 *
 * This code initiates a connection to a server. It first checks to make
 * sure the given server exists. If this is the case, it creates a socket,
 * creates a client, saves the socket information in the client, and
 * initiates a connection to the server through rb_connect_tcp(). The
 * completion of this goes through serv_completed_connection().
 *
 * We return 1 if the connection is attempted, since we don't know whether
 * it suceeded or not, and 0 if it fails in here somewhere.
 */
int
serv_connect(struct server_conf *server_p, struct Client *by)
{
        struct Client *client_p;
        struct sockaddr_storage sa_connect[2];
        struct sockaddr_storage sa_bind[ARRAY_SIZE(sa_connect)];
        char note[HOSTLEN + 10];
        rb_fde_t *F;

        s_assert(server_p != NULL);
        if(server_p == NULL)
                return 0;

        for (int i = 0; i < ARRAY_SIZE(sa_connect); i++) {
                SET_SS_FAMILY(&sa_connect[i], AF_UNSPEC);
                SET_SS_FAMILY(&sa_bind[i], AF_UNSPEC);
        }

        if(server_p->aftype == AF_UNSPEC
                && GET_SS_FAMILY(&server_p->connect4) == AF_INET
                && GET_SS_FAMILY(&server_p->connect6) == AF_INET6)
        {
                if(rand() % 2 == 0)
                {
                        sa_connect[0] = server_p->connect4;
                        sa_connect[1] = server_p->connect6;
                        sa_bind[0] = server_p->bind4;
                        sa_bind[1] = server_p->bind6;
                }
                else
                {
                        sa_connect[0] = server_p->connect6;
                        sa_connect[1] = server_p->connect4;
                        sa_bind[0] = server_p->bind6;
                        sa_bind[1] = server_p->bind4;
                }
        }
        else if(server_p->aftype == AF_INET || GET_SS_FAMILY(&server_p->connect4) == AF_INET)
        {
                sa_connect[0] = server_p->connect4;
                sa_bind[0] = server_p->bind4;
        }
        else if(server_p->aftype == AF_INET6 || GET_SS_FAMILY(&server_p->connect6) == AF_INET6)
        {
                sa_connect[0] = server_p->connect6;
                sa_bind[0] = server_p->bind6;
        }

        /* log */
#ifdef HAVE_LIBSCTP
        if (ServerConfSCTP(server_p) && GET_SS_FAMILY(&sa_connect[1]) != AF_UNSPEC) {
                char buf2[HOSTLEN + 1];

                buf[0] = 0;
                buf2[0] = 0;
                rb_inet_ntop_sock((struct sockaddr *)&sa_connect[0], buf, sizeof(buf));
                rb_inet_ntop_sock((struct sockaddr *)&sa_connect[1], buf2, sizeof(buf2));
                ilog(L_SERVER, "Connect to *[%s] @%s&%s", server_p->name, buf, buf2);
        } else {
#else
        {
#endif
                buf[0] = 0;
                rb_inet_ntop_sock((struct sockaddr *)&sa_connect[0], buf, sizeof(buf));
                ilog(L_SERVER, "Connect to *[%s] @%s", server_p->name, buf);
        }

        /*
         * Make sure this server isn't already connected
         */
        if((client_p = find_server(NULL, server_p->name)))
        {
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                     "Server %s already present from %s",
                                     server_p->name, client_p->name);
                if(by && IsPerson(by) && !MyClient(by))
                        sendto_one_notice(by, ":Server %s already present from %s",
                                          server_p->name, client_p->name);
                return 0;
        }

        if (CurrUsers(server_p->class) >= MaxUsers(server_p->class)) {
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                     "No more connections allowed in class \"%s\" for server %s",
                                     server_p->class->class_name, server_p->name);
                if(by && IsPerson(by) && !MyClient(by))
                        sendto_one_notice(by, ":No more connections allowed in class \"%s\" for server %s",
                                     server_p->class->class_name, server_p->name);
                return 0;
        }

        /* create a socket for the server connection */
        if(GET_SS_FAMILY(&sa_connect[0]) == AF_UNSPEC) {
                ilog_error("unspecified socket address family");
                return 0;
#ifdef HAVE_LIBSCTP
        } else if (ServerConfSCTP(server_p)) {
                if ((F = rb_socket(AF_INET6, SOCK_STREAM, IPPROTO_SCTP, NULL)) == NULL) {
                        ilog_error("opening a stream socket");
                        return 0;
                }
#endif
        } else if ((F = rb_socket(GET_SS_FAMILY(&sa_connect[0]), SOCK_STREAM, IPPROTO_TCP, NULL)) == NULL) {
                ilog_error("opening a stream socket");
                return 0;
        }

        /* servernames are always guaranteed under HOSTLEN chars */
        snprintf(note, sizeof(note), "Server: %s", server_p->name);
        rb_note(F, note);

        /* Create a local client */
        client_p = make_client(NULL);

        /* Copy in the server, hostname, fd */
        rb_strlcpy(client_p->name, server_p->name, sizeof(client_p->name));
        if(server_p->connect_host)
                rb_strlcpy(client_p->host, server_p->connect_host, sizeof(client_p->host));
        else
                rb_strlcpy(client_p->host, buf, sizeof(client_p->host));
        rb_strlcpy(client_p->sockhost, buf, sizeof(client_p->sockhost));
        client_p->localClient->F = F;
        /* shove the port number into the sockaddr */
        SET_SS_PORT(&sa_connect[0], htons(server_p->port));
        SET_SS_PORT(&sa_connect[1], htons(server_p->port));

        /*
         * Set up the initial server evilness, ripped straight from
         * connect_server(), so don't blame me for it being evil.
         *   -- adrian
         */

        if(!rb_set_buffers(client_p->localClient->F, READBUF_SIZE))
        {
                ilog_error("setting the buffer size for a server connection");
        }

        /*
         * Attach config entries to client here rather than in
         * serv_connect_callback(). This to avoid null pointer references.
         */
        attach_server_conf(client_p, server_p);

        /*
         * at this point we have a connection in progress and C/N lines
         * attached to the client, the socket info should be saved in the
         * client and it should either be resolved or have a valid address.
         *
         * The socket has been connected or connect is in progress.
         */
        make_server(client_p);
        if(by && IsClient(by))
                rb_strlcpy(client_p->serv->by, by->name, sizeof(client_p->serv->by));
        else
                strcpy(client_p->serv->by, "AutoConn.");

        SetConnecting(client_p);
        rb_dlinkAddTail(client_p, &client_p->node, &global_client_list);

        for (int i = 0; i < ARRAY_SIZE(sa_connect); i++) {
                if (GET_SS_FAMILY(&sa_bind[i]) == AF_UNSPEC) {
                        if (GET_SS_FAMILY(&sa_connect[i]) == GET_SS_FAMILY(&ServerInfo.bind4))
                                sa_bind[i] = ServerInfo.bind4;
                        if (GET_SS_FAMILY(&sa_connect[i]) == GET_SS_FAMILY(&ServerInfo.bind6))
                                sa_bind[i] = ServerInfo.bind6;
                }
        }

#ifdef HAVE_LIBSCTP
        if (ServerConfSCTP(server_p)) {
                rb_connect_sctp(client_p->localClient->F,
                        sa_connect, ARRAY_SIZE(sa_connect), sa_bind, ARRAY_SIZE(sa_bind),
                        ServerConfSSL(server_p) ? serv_connect_ssl_callback : serv_connect_callback,
                        client_p, ConfigFileEntry.connect_timeout);
        } else {
#else
        {
#endif
                rb_connect_tcp(client_p->localClient->F,
                        (struct sockaddr *)&sa_connect[0],
                        GET_SS_FAMILY(&sa_bind[0]) == AF_UNSPEC ? NULL : (struct sockaddr *)&sa_bind[0],
                        ServerConfSSL(server_p) ? serv_connect_ssl_callback : serv_connect_callback,
                        client_p, ConfigFileEntry.connect_timeout);
        }
        return 1;
}

static void
serv_connect_ssl_callback(rb_fde_t *F, int status, void *data)
{
        struct Client *client_p = data;
        rb_fde_t *xF[2];
        rb_connect_sockaddr(F, (struct sockaddr *)&client_p->localClient->ip, sizeof(client_p->localClient->ip));
        if(status != RB_OK)
        {
                /* Print error message, just like non-SSL. */
                serv_connect_callback(F, status, data);
                return;
        }
        if(rb_socketpair(AF_UNIX, SOCK_STREAM, 0, &xF[0], &xF[1], "Outgoing ssld connection") == -1)
        {
                ilog_error("rb_socketpair failed for server");
                serv_connect_callback(F, RB_ERROR, data);
                return;

        }
        client_p->localClient->F = xF[0];
        client_p->localClient->ssl_callback = serv_connect_ssl_open_callback;

        client_p->localClient->ssl_ctl = start_ssld_connect(F, xF[1], connid_get(client_p));
        if(!client_p->localClient->ssl_ctl)
        {
                serv_connect_callback(client_p->localClient->F, RB_ERROR, data);
                return;
        }
        SetSSL(client_p);
}

static int
serv_connect_ssl_open_callback(struct Client *client_p, int status)
{
        serv_connect_callback(client_p->localClient->F, status, client_p);
        return 1; /* suppress default exit_client handler for status != RB_OK */
}

/*
 * serv_connect_callback() - complete a server connection.
 *
 * This routine is called after the server connection attempt has
 * completed. If unsucessful, an error is sent to ops and the client
 * is closed. If sucessful, it goes through the initialisation/check
 * procedures, the capabilities are sent, and the socket is then
 * marked for reading.
 */
static void
serv_connect_callback(rb_fde_t *F, int status, void *data)
{
        struct Client *client_p = data;
        struct server_conf *server_p;
        char *errstr;

        /* First, make sure its a real client! */
        s_assert(client_p != NULL);
        s_assert(client_p->localClient->F == F);

        if(client_p == NULL)
                return;

        /* while we were waiting for the callback, its possible this already
         * linked in.. --fl
         */
        if(find_server(NULL, client_p->name) != NULL)
        {
                exit_client(client_p, client_p, &me, "Server Exists");
                return;
        }

        if(client_p->localClient->ssl_ctl == NULL)
                rb_connect_sockaddr(F, (struct sockaddr *)&client_p->localClient->ip, sizeof(client_p->localClient->ip));

        /* Check the status */
        if(status != RB_OK)
        {
                /* COMM_ERR_TIMEOUT wont have an errno associated with it,
                 * the others will.. --fl
                 */
                if(status == RB_ERR_TIMEOUT || status == RB_ERROR_SSL)
                {
                        sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                        "Error connecting to %s[%s]: %s",
                                        client_p->name,
                                        "255.255.255.255",
                                        rb_errstr(status));
                        ilog(L_SERVER, "Error connecting to %s[%s]: %s",
                                client_p->name, client_p->sockhost,
                                rb_errstr(status));
                }
                else
                {
                        errstr = strerror(rb_get_sockerr(F));
                        sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                        "Error connecting to %s[%s]: %s (%s)",
                                        client_p->name,
                                        "255.255.255.255",
                                        rb_errstr(status), errstr);
                        ilog(L_SERVER, "Error connecting to %s[%s]: %s (%s)",
                                client_p->name, client_p->sockhost,
                                rb_errstr(status), errstr);
                }

                exit_client(client_p, client_p, &me, rb_errstr(status));
                return;
        }

        /* COMM_OK, so continue the connection procedure */
        /* Get the C/N lines */
        if((server_p = client_p->localClient->att_sconf) == NULL)
        {
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE, "Lost connect{} block for %s",
                                client_p->name);
                exit_client(client_p, client_p, &me, "Lost connect{} block");
                return;
        }

        if(server_p->certfp && (!client_p->certfp || rb_strcasecmp(server_p->certfp, client_p->certfp) != 0))
        {
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                     "Connection to %s has invalid certificate fingerprint %s",
                     client_p->name, client_p->certfp);
                ilog(L_SERVER, "Access denied, invalid certificate fingerprint %s from %s",
                     client_p->certfp, log_client_name(client_p, SHOW_IP));

                exit_client(client_p, client_p, &me, "Invalid fingerprint.");
                return;
        }

        /* Next, send the initial handshake */
        SetHandshake(client_p);

        /* the server may be linking based on certificate fingerprint now. --nenolod */
        sendto_one(client_p, "PASS %s TS %d :%s",
                   EmptyString(server_p->spasswd) ? "*" : server_p->spasswd, TS_CURRENT, me.id);

        /* pass my info to the new server */
        send_capabilities(client_p, default_server_capabs | CAP_MASK
                          | (ServerConfCompressed(server_p) ? CAP_ZIP_SUPPORTED : 0)
                          | (ServerConfTb(server_p) ? CAP_TB : 0));

        sendto_one(client_p, "SERVER %s 1 :%s%s",
                   me.name,
                   ConfigServerHide.hidden ? "(H) " : "", me.info);

        /*
         * If we've been marked dead because a send failed, just exit
         * here now and save everyone the trouble of us ever existing.
         */
        if(IsAnyDead(client_p))
        {
                sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
                                     "%s went dead during handshake", client_p->name);
                exit_client(client_p, client_p, &me, "Went dead during handshake");
                return;
        }

        /* don't move to serv_list yet -- we haven't sent a burst! */

        /* If we get here, we're ok, so lets start reading some data */
        read_packet(F, client_p);
}