[DCCP]: Initial implementation

Development to this point was done on a subversion repository at:

http://oops.ghostprotocols.net:81/cgi-bin/viewcvs.cgi/dccp-2.6/

This repository will be kept at this site for the foreseable future,
so that interested parties can see the history of this code,
attributions, etc.

If I ever decide to take this offline I'll provide the full history at
some other suitable place.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 199 insertions, 0 deletions

diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
new file mode 100644
index 000000000000..810f0c293b85
--- /dev/null
+++ b/net/dccp/minisocks.c
@@ -0,0 +1,199 @@
+/*
+ *  net/dccp/minisocks.c
+ *
+ *  An implementation of the DCCP protocol
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *      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.
+ */
+
+#include <linux/config.h>
+#include <linux/dccp.h>
+#include <linux/skbuff.h>
+#include <linux/timer.h>
+
+#include <net/sock.h>
+#include <net/xfrm.h>
+#include <net/inet_timewait_sock.h>
+
+#include "ccid.h"
+#include "dccp.h"
+
+void dccp_time_wait(struct sock *sk, int state, int timeo)
+{
+        /* FIXME: Implement */
+        dccp_pr_debug("Want to help? Start here\n");
+        dccp_set_state(sk, state);
+}
+
+/* This is for handling early-kills of TIME_WAIT sockets. */
+void dccp_tw_deschedule(struct inet_timewait_sock *tw)
+{
+        dccp_pr_debug("Want to help? Start here\n");
+        __inet_twsk_kill(tw, &dccp_hashinfo);
+}
+
+struct sock *dccp_create_openreq_child(struct sock *sk,
+                                       const struct request_sock *req,
+                                       const struct sk_buff *skb)
+{
+        /*
+         * Step 3: Process LISTEN state
+         *
+         * // Generate a new socket and switch to that socket
+         * Set S := new socket for this port pair
+         */
+        struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
+
+        if (newsk != NULL) {
+                const struct dccp_request_sock *dreq = dccp_rsk(req);
+                struct inet_connection_sock *newicsk = inet_csk(sk);
+                struct dccp_sock *newdp = dccp_sk(newsk);
+
+                newdp->dccps_hc_rx_ackpkts = NULL;
+                newdp->dccps_role = DCCP_ROLE_SERVER;
+                newicsk->icsk_rto = TCP_TIMEOUT_INIT;
+
+                if (newdp->dccps_options.dccpo_send_ack_vector) {
+                        newdp->dccps_hc_rx_ackpkts = dccp_ackpkts_alloc(DCCP_MAX_ACK_VECTOR_LEN,
+                                                                        GFP_ATOMIC);
+                        /*
+                         * XXX: We're using the same CCIDs set on the parent, i.e. sk_clone
+                         * copied the master sock and left the CCID pointers for this child,
+                         * that is why we do the __ccid_get calls.
+                         */
+                        if (unlikely(newdp->dccps_hc_rx_ackpkts == NULL))
+                                goto out_free;
+                }
+
+                if (unlikely(ccid_hc_rx_init(newdp->dccps_hc_rx_ccid, newsk) != 0 ||
+                             ccid_hc_tx_init(newdp->dccps_hc_tx_ccid, newsk) != 0)) {
+                        dccp_ackpkts_free(newdp->dccps_hc_rx_ackpkts);
+                        ccid_hc_rx_exit(newdp->dccps_hc_rx_ccid, newsk);
+                        ccid_hc_tx_exit(newdp->dccps_hc_tx_ccid, newsk);
+out_free:
+                        /* It is still raw copy of parent, so invalidate
+                         * destructor and make plain sk_free() */
+                        newsk->sk_destruct = NULL;
+                        sk_free(newsk);
+                        return NULL;
+                }
+
+                __ccid_get(newdp->dccps_hc_rx_ccid);
+                __ccid_get(newdp->dccps_hc_tx_ccid);
+
+                /*
+                 * Step 3: Process LISTEN state
+                 *
+                 *      Choose S.ISS (initial seqno) or set from Init Cookie
+                 *      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
+                 */
+
+                /* See dccp_v4_conn_request */
+                newdp->dccps_options.dccpo_sequence_window = req->rcv_wnd;
+
+                newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
+                dccp_update_gsr(newsk, dreq->dreq_isr);
+
+                newdp->dccps_iss = dreq->dreq_iss;
+                dccp_update_gss(newsk, dreq->dreq_iss);
+
+                dccp_init_xmit_timers(newsk);
+
+                DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
+        }
+        return newsk;
+}
+
+/* 
+ * Process an incoming packet for RESPOND sockets represented
+ * as an request_sock.
+ */
+struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
+                            struct request_sock *req,
+                            struct request_sock **prev)
+{
+        struct sock *child = NULL;
+
+        /* Check for retransmitted REQUEST */
+        if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
+                if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dccp_rsk(req)->dreq_isr)) {
+                        struct dccp_request_sock *dreq = dccp_rsk(req);
+
+                        dccp_pr_debug("Retransmitted REQUEST\n");
+                        /* Send another RESPONSE packet */
+                        dccp_set_seqno(&dreq->dreq_iss, dreq->dreq_iss + 1);
+                        dccp_set_seqno(&dreq->dreq_isr, DCCP_SKB_CB(skb)->dccpd_seq);
+                        req->rsk_ops->rtx_syn_ack(sk, req, NULL);
+                }
+                /* Network Duplicate, discard packet */
+                return NULL;
+        }
+
+        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
+
+        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
+            dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
+                goto drop;
+
+        /* Invalid ACK */
+        if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
+                dccp_pr_debug("Invalid ACK number: ack_seq=%llu, dreq_iss=%llu\n",
+                              DCCP_SKB_CB(skb)->dccpd_ack_seq, dccp_rsk(req)->dreq_iss);
+                goto drop;
+        }
+
+        child = dccp_v4_request_recv_sock(sk, skb, req, NULL);
+        if (child == NULL)
+                goto listen_overflow;
+
+        /* FIXME: deal with options */
+
+        inet_csk_reqsk_queue_unlink(sk, req, prev);
+        inet_csk_reqsk_queue_removed(sk, req);
+        inet_csk_reqsk_queue_add(sk, req, child);
+out:
+        return child;
+listen_overflow:
+        dccp_pr_debug("listen_overflow!\n");
+        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
+drop:
+        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
+                req->rsk_ops->send_reset(skb);
+
+        inet_csk_reqsk_queue_drop(sk, req, prev);
+        goto out;
+}
+
+/*
+ *  Queue segment on the new socket if the new socket is active,
+ *  otherwise we just shortcircuit this and continue with
+ *  the new socket.
+ */
+int dccp_child_process(struct sock *parent, struct sock *child,
+                       struct sk_buff *skb)
+{
+        int ret = 0;
+        const int state = child->sk_state;
+
+        if (!sock_owned_by_user(child)) {
+                ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb), skb->len);
+
+                /* Wakeup parent, send SIGIO */
+                if (state == DCCP_RESPOND && child->sk_state != state)
+                        parent->sk_data_ready(parent, 0);
+        } else {
+                /* Alas, it is possible again, because we do lookup
+                 * in main socket hash table and lock on listening
+                 * socket does not protect us more.
+                 */
+                sk_add_backlog(child, skb);
+        }
+
+        bh_unlock_sock(child);
+        sock_put(child);
+        return ret;
+}