- crWaitUntil(pktin);
- if (pktin->type != SSH2_MSG_KEX_DH_GEX_GROUP) {
- bombout(("expected key exchange group packet from server"));
- crStop(0);
- }
- s->p = ssh2_pkt_getmp(pktin);
- s->g = ssh2_pkt_getmp(pktin);
- if (!s->p || !s->g) {
- bombout(("unable to read mp-ints from incoming group packet"));
- crStop(0);
- }
- ssh->kex_ctx = dh_setup_gex(s->p, s->g);
- s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
- s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
- } else {
- ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP;
- ssh->kex_ctx = dh_setup_group(ssh->kex);
- s->kex_init_value = SSH2_MSG_KEXDH_INIT;
- s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
- logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
- ssh->kex->groupname);
- }
+ /*
+ * If we're doing Diffie-Hellman group exchange, start by
+ * requesting a group.
+ */
+ if (!ssh->kex->pdata) {
+ logevent("Doing Diffie-Hellman group exchange");
+ ssh->pkt_ctx |= SSH2_PKTCTX_DHGEX;
+ /*
+ * Work out how big a DH group we will need to allow that
+ * much data.
+ */
+ s->pbits = 512 << ((s->nbits - 1) / 64);
+ s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
+ ssh2_pkt_adduint32(s->pktout, s->pbits);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);