extern const struct ssh_kex ssh_diffiehellman;
const static struct ssh_kex *kex_algs[] = { &ssh_diffiehellman };

extern const struct ssh_hostkey ssh_dss;
const static struct ssh_hostkey *hostkey_algs[] = { &ssh_dss };

extern const struct ssh_mac ssh_md5, ssh_sha1, ssh_sha1_buggy;

static void nullmac_key(unsigned char *key) { }
static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { }
static int nullmac_verify(unsigned char *blk, int len, unsigned long seq) { return 1; }
const static struct ssh_mac ssh_mac_none = {
    nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
};
const static struct ssh_mac *macs[] = {
    &ssh_sha1, &ssh_md5, &ssh_mac_none };
const static struct ssh_mac *buggymacs[] = {
    &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none };

const static struct ssh_compress ssh_comp_none = {
    "none"
};
const static struct ssh_compress *compressions[] = { &ssh_comp_none };

/*

 */
static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
{
    static int i, len;
    static char *str;
    static Bignum e, f, K;
    static const struct ssh_mac **maclist;
    static int nmacs;
    static const struct ssh_cipher *cscipher_tobe = NULL;
    static const struct ssh_cipher *sccipher_tobe = NULL;
    static const struct ssh_mac *csmac_tobe = NULL;
    static const struct ssh_mac *scmac_tobe = NULL;
    static const struct ssh_compress *cscomp_tobe = NULL;
    static const struct ssh_compress *sccomp_tobe = NULL;
    static char *hostkeydata, *sigdata, *keystr, *fingerprint;

        preferred_cipher = &ssh_3des_ssh2;
    }

    /*
     * Be prepared to work around the buggy MAC problem.
     */
    if (cfg.buggymac)
        maclist = buggymacs, nmacs = lenof(buggymacs);
    else
        maclist = macs, nmacs = lenof(macs);

    begin_key_exchange:
    /*
     * Construct and send our key exchange packet.
     */
    ssh2_pkt_init(SSH2_MSG_KEXINIT);
    for (i = 0; i < 16; i++)

        const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
        ssh2_pkt_addstring_str(c->name);
        if (i < lenof(ciphers))
            ssh2_pkt_addstring_str(",");
    }
    /* List client->server MAC algorithms. */
    ssh2_pkt_addstring_start();
    for (i = 0; i < nmacs; i++) {
        ssh2_pkt_addstring_str(maclist[i]->name);
        if (i < nmacs-1)
            ssh2_pkt_addstring_str(",");
    }
    /* List server->client MAC algorithms. */
    ssh2_pkt_addstring_start();
    for (i = 0; i < nmacs; i++) {
        ssh2_pkt_addstring_str(maclist[i]->name);
        if (i < nmacs-1)
            ssh2_pkt_addstring_str(",");
    }
    /* List client->server compression algorithms. */
    ssh2_pkt_addstring_start();
    for (i = 0; i < lenof(compressions); i++) {
        ssh2_pkt_addstring_str(compressions[i]->name);
        if (i < lenof(compressions)-1)

        const struct ssh_cipher *c = i==0 ? preferred_cipher : ciphers[i-1];
        if (in_commasep_string(c->name, str, len)) {
            sccipher_tobe = c;
            break;
        }
    }
    ssh2_pkt_getstring(&str, &len);    /* client->server mac */
    for (i = 0; i < nmacs; i++) {
        if (in_commasep_string(maclist[i]->name, str, len)) {
            csmac_tobe = maclist[i];
            break;
        }
    }
    ssh2_pkt_getstring(&str, &len);    /* server->client mac */
    for (i = 0; i < nmacs; i++) {
        if (in_commasep_string(maclist[i]->name, str, len)) {
            scmac_tobe = maclist[i];
            break;
        }
    }
    ssh2_pkt_getstring(&str, &len);    /* client->server compression */
    for (i = 0; i < lenof(compressions); i++) {