]> err.no Git - linux-2.6/blobdiff - net/dccp/ipv4.c
[DCCP]: Update code comments for Step 2/3
[linux-2.6] / net / dccp / ipv4.c
index e08e7688a263c82d0aca759a0bf68afd30b12392..91bffaa761a63b650ac95fe292e6cb75c08d99c1 100644 (file)
@@ -193,86 +193,6 @@ static inline void dccp_do_pmtu_discovery(struct sock *sk,
        } /* else let the usual retransmit timer handle it */
 }
 
-static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
-                                  struct request_sock *req)
-{
-       int err;
-       struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
-       const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
-                                    sizeof(struct dccp_hdr_ext) +
-                                    sizeof(struct dccp_hdr_ack_bits);
-       struct sk_buff *skb;
-
-       if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
-               return;
-
-       skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
-       if (skb == NULL)
-               return;
-
-       /* Reserve space for headers. */
-       skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
-
-       skb->dst = dst_clone(rxskb->dst);
-
-       skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
-       dh = dccp_hdr(skb);
-       memset(dh, 0, dccp_hdr_ack_len);
-
-       /* Build DCCP header and checksum it. */
-       dh->dccph_type     = DCCP_PKT_ACK;
-       dh->dccph_sport    = rxdh->dccph_dport;
-       dh->dccph_dport    = rxdh->dccph_sport;
-       dh->dccph_doff     = dccp_hdr_ack_len / 4;
-       dh->dccph_x        = 1;
-
-       dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
-       dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
-                        DCCP_SKB_CB(rxskb)->dccpd_seq);
-
-       bh_lock_sock(dccp_v4_ctl_socket->sk);
-       err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
-                                   rxskb->nh.iph->daddr,
-                                   rxskb->nh.iph->saddr, NULL);
-       bh_unlock_sock(dccp_v4_ctl_socket->sk);
-
-       if (err == NET_XMIT_CN || err == 0) {
-               DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
-               DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
-       }
-}
-
-static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
-                                struct dst_entry *dst)
-{
-       int err = -1;
-       struct sk_buff *skb;
-
-       /* First, grab a route. */
-       
-       if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
-               goto out;
-
-       skb = dccp_make_response(sk, dst, req);
-       if (skb != NULL) {
-               const struct inet_request_sock *ireq = inet_rsk(req);
-               struct dccp_hdr *dh = dccp_hdr(skb);
-
-               dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
-                                                     ireq->rmt_addr);
-               memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
-               err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
-                                           ireq->rmt_addr,
-                                           ireq->opt);
-               if (err == NET_XMIT_CN)
-                       err = 0;
-       }
-
-out:
-       dst_release(dst);
-       return err;
-}
-
 /*
  * This routine is called by the ICMP module when it gets some sort of error
  * condition. If err < 0 then the socket should be closed and the error
@@ -449,95 +369,6 @@ static inline u64 dccp_v4_init_sequence(const struct sock *sk,
                                           dccp_hdr(skb)->dccph_sport);
 }
 
-static struct request_sock_ops dccp_request_sock_ops;
-
-int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
-{
-       struct inet_request_sock *ireq;
-       struct dccp_sock dp;
-       struct request_sock *req;
-       struct dccp_request_sock *dreq;
-       const __be32 saddr = skb->nh.iph->saddr;
-       const __be32 daddr = skb->nh.iph->daddr;
-       const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
-       struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
-       __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
-
-       /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
-       if (((struct rtable *)skb->dst)->rt_flags &
-           (RTCF_BROADCAST | RTCF_MULTICAST)) {
-               reset_code = DCCP_RESET_CODE_NO_CONNECTION;
-               goto drop;
-       }
-
-       if (dccp_bad_service_code(sk, service)) {
-               reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
-               goto drop;
-       }
-       /*
-        * TW buckets are converted to open requests without
-        * limitations, they conserve resources and peer is
-        * evidently real one.
-        */
-       if (inet_csk_reqsk_queue_is_full(sk))
-               goto drop;
-
-       /*
-        * Accept backlog is full. If we have already queued enough
-        * of warm entries in syn queue, drop request. It is better than
-        * clogging syn queue with openreqs with exponentially increasing
-        * timeout.
-        */
-       if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
-               goto drop;
-
-       req = reqsk_alloc(&dccp_request_sock_ops);
-       if (req == NULL)
-               goto drop;
-
-       if (dccp_parse_options(sk, skb))
-               goto drop_and_free;
-
-       dccp_openreq_init(req, &dp, skb);
-
-       if (security_inet_conn_request(sk, skb, req))
-               goto drop_and_free;
-
-       ireq = inet_rsk(req);
-       ireq->loc_addr = daddr;
-       ireq->rmt_addr = saddr;
-       req->rcv_wnd    = dccp_feat_default_sequence_window;
-       ireq->opt       = NULL;
-
-       /* 
-        * Step 3: Process LISTEN state
-        *
-        * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
-        *
-        * In fact we defer setting S.GSR, S.SWL, S.SWH to
-        * dccp_create_openreq_child.
-        */
-       dreq = dccp_rsk(req);
-       dreq->dreq_isr     = dcb->dccpd_seq;
-       dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
-       dreq->dreq_service = service;
-
-       if (dccp_v4_send_response(sk, req, NULL))
-               goto drop_and_free;
-
-       inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
-       return 0;
-
-drop_and_free:
-       reqsk_free(req);
-drop:
-       DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
-       dcb->dccpd_reset_code = reset_code;
-       return -1;
-}
-
-EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
-
 /*
  * The three way handshake has completed - we got a valid ACK or DATAACK -
  * now create the new socket.
@@ -689,6 +520,37 @@ static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
        return &rt->u.dst;
 }
 
+static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
+                                struct dst_entry *dst)
+{
+       int err = -1;
+       struct sk_buff *skb;
+
+       /* First, grab a route. */
+       
+       if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
+               goto out;
+
+       skb = dccp_make_response(sk, dst, req);
+       if (skb != NULL) {
+               const struct inet_request_sock *ireq = inet_rsk(req);
+               struct dccp_hdr *dh = dccp_hdr(skb);
+
+               dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
+                                                     ireq->rmt_addr);
+               memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+               err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
+                                           ireq->rmt_addr,
+                                           ireq->opt);
+               if (err == NET_XMIT_CN)
+                       err = 0;
+       }
+
+out:
+       dst_release(dst);
+       return err;
+}
+
 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
 {
        int err;
@@ -720,9 +582,7 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
        skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
        skb->dst = dst_clone(dst);
 
-       skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
-       dh = dccp_hdr(skb);
-       memset(dh, 0, dccp_hdr_reset_len);
+       dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
 
        /* Build DCCP header and checksum it. */
        dh->dccph_type     = DCCP_PKT_RESET;
@@ -759,6 +619,104 @@ out:
         dst_release(dst);
 }
 
+static void dccp_v4_reqsk_destructor(struct request_sock *req)
+{
+       kfree(inet_rsk(req)->opt);
+}
+
+static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
+       .family         = PF_INET,
+       .obj_size       = sizeof(struct dccp_request_sock),
+       .rtx_syn_ack    = dccp_v4_send_response,
+       .send_ack       = dccp_reqsk_send_ack,
+       .destructor     = dccp_v4_reqsk_destructor,
+       .send_reset     = dccp_v4_ctl_send_reset,
+};
+
+int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+       struct inet_request_sock *ireq;
+       struct request_sock *req;
+       struct dccp_request_sock *dreq;
+       const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
+       struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+       __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
+
+       /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
+       if (((struct rtable *)skb->dst)->rt_flags &
+           (RTCF_BROADCAST | RTCF_MULTICAST)) {
+               reset_code = DCCP_RESET_CODE_NO_CONNECTION;
+               goto drop;
+       }
+
+       if (dccp_bad_service_code(sk, service)) {
+               reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
+               goto drop;
+       }
+       /*
+        * TW buckets are converted to open requests without
+        * limitations, they conserve resources and peer is
+        * evidently real one.
+        */
+       if (inet_csk_reqsk_queue_is_full(sk))
+               goto drop;
+
+       /*
+        * Accept backlog is full. If we have already queued enough
+        * of warm entries in syn queue, drop request. It is better than
+        * clogging syn queue with openreqs with exponentially increasing
+        * timeout.
+        */
+       if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
+               goto drop;
+
+       req = reqsk_alloc(&dccp_request_sock_ops);
+       if (req == NULL)
+               goto drop;
+
+       if (dccp_parse_options(sk, skb))
+               goto drop_and_free;
+
+       dccp_reqsk_init(req, skb);
+
+       if (security_inet_conn_request(sk, skb, req))
+               goto drop_and_free;
+
+       ireq = inet_rsk(req);
+       ireq->loc_addr = skb->nh.iph->daddr;
+       ireq->rmt_addr = skb->nh.iph->saddr;
+       req->rcv_wnd    = dccp_feat_default_sequence_window;
+       ireq->opt       = NULL;
+
+       /* 
+        * Step 3: Process LISTEN state
+        *
+        * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
+        *
+        * In fact we defer setting S.GSR, S.SWL, S.SWH to
+        * dccp_create_openreq_child.
+        */
+       dreq = dccp_rsk(req);
+       dreq->dreq_isr     = dcb->dccpd_seq;
+       dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
+       dreq->dreq_service = service;
+
+       if (dccp_v4_send_response(sk, req, NULL))
+               goto drop_and_free;
+
+       inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
+       return 0;
+
+drop_and_free:
+       reqsk_free(req);
+drop:
+       DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
+       dcb->dccpd_reset_code = reset_code;
+       return -1;
+}
+
+EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
+
 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 {
        struct dccp_hdr *dh = dccp_hdr(skb);
@@ -771,24 +729,23 @@ int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 
        /*
         *  Step 3: Process LISTEN state
-        *     If S.state == LISTEN,
-        *        If P.type == Request or P contains a valid Init Cookie
-        *              option,
-        *           * Must scan the packet's options to check for an Init
-        *              Cookie.  Only the Init Cookie is processed here,
-        *              however; other options are processed in Step 8.  This
-        *              scan need only be performed if the endpoint uses Init
-        *              Cookies *
-        *           * Generate a new socket and switch to that socket *
-        *           Set S := new socket for this port pair
-        *           S.state = RESPOND
-        *           Choose S.ISS (initial seqno) or set from Init Cookie
-        *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
-        *           Continue with S.state == RESPOND
-        *           * A Response packet will be generated in Step 11 *
-        *        Otherwise,
-        *           Generate Reset(No Connection) unless P.type == Reset
-        *           Drop packet and return
+        *       If P.type == Request or P contains a valid Init Cookie option,
+        *            (* Must scan the packet's options to check for Init
+        *               Cookies.  Only Init Cookies are processed here,
+        *               however; other options are processed in Step 8.  This
+        *               scan need only be performed if the endpoint uses Init
+        *               Cookies *)
+        *            (* Generate a new socket and switch to that socket *)
+        *            Set S := new socket for this port pair
+        *            S.state = RESPOND
+        *            Choose S.ISS (initial seqno) or set from Init Cookies
+        *            Initialize S.GAR := S.ISS
+        *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
+        *            Continue with S.state == RESPOND
+        *            (* A Response packet will be generated in Step 11 *)
+        *       Otherwise,
+        *            Generate Reset(No Connection) unless P.type == Reset
+        *            Drop packet and return
         *
         * NOTE: the check for the packet types is done in
         *       dccp_rcv_state_process
@@ -915,8 +872,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
                dccp_pr_debug_cat("\n");
        } else {
                DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
-               dccp_pr_debug_cat(", ack=%llu\n",
-                                 (unsigned long long)
+               dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
                                  DCCP_SKB_CB(skb)->dccpd_ack_seq);
        }
 
@@ -930,8 +886,6 @@ static int dccp_v4_rcv(struct sk_buff *skb)
        /* 
         * Step 2:
         *      If no socket ...
-        *              Generate Reset(No Connection) unless P.type == Reset
-        *              Drop packet and return
         */
        if (sk == NULL) {
                dccp_pr_debug("failed to look up flow ID in table and "
@@ -945,11 +899,10 @@ static int dccp_v4_rcv(struct sk_buff *skb)
         *              Generate Reset(No Connection) unless P.type == Reset
         *              Drop packet and return
         */
-              
        if (sk->sk_state == DCCP_TIME_WAIT) {
-               dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
-                             "do_time_wait\n");
-                goto do_time_wait;
+               dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
+               inet_twsk_put(inet_twsk(sk));
+               goto no_dccp_socket;
        }
 
        if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
@@ -963,6 +916,7 @@ no_dccp_socket:
                goto discard_it;
        /*
         * Step 2:
+        *      If no socket ...
         *              Generate Reset(No Connection) unless P.type == Reset
         *              Drop packet and return
         */
@@ -973,17 +927,12 @@ no_dccp_socket:
        }
 
 discard_it:
-       /* Discard frame. */
        kfree_skb(skb);
        return 0;
 
 discard_and_relse:
        sock_put(sk);
        goto discard_it;
-
-do_time_wait:
-       inet_twsk_put(inet_twsk(sk));
-       goto no_dccp_socket;
 }
 
 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
@@ -1017,20 +966,6 @@ static int dccp_v4_init_sock(struct sock *sk)
        return err;
 }
 
-static void dccp_v4_reqsk_destructor(struct request_sock *req)
-{
-       kfree(inet_rsk(req)->opt);
-}
-
-static struct request_sock_ops dccp_request_sock_ops = {
-       .family         = PF_INET,
-       .obj_size       = sizeof(struct dccp_request_sock),
-       .rtx_syn_ack    = dccp_v4_send_response,
-       .send_ack       = dccp_v4_reqsk_send_ack,
-       .destructor     = dccp_v4_reqsk_destructor,
-       .send_reset     = dccp_v4_ctl_send_reset,
-};
-
 static struct timewait_sock_ops dccp_timewait_sock_ops = {
        .twsk_obj_size  = sizeof(struct inet_timewait_sock),
 };