/* answer offending packet in @rcv_skb with Reset from control socket @ctl */ struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb) { struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh; struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb); const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext) + sizeof(struct dccp_hdr_reset); struct dccp_hdr_reset *dhr; struct sk_buff *skb; skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); if (skb == NULL) return NULL; skb_reserve(skb, sk->sk_prot->max_header); /* Swap the send and the receive. */ dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len); dh->dccph_type = DCCP_PKT_RESET; dh->dccph_sport = rxdh->dccph_dport; dh->dccph_dport = rxdh->dccph_sport; dh->dccph_doff = dccp_hdr_reset_len / 4; dh->dccph_x = 1; dhr = dccp_hdr_reset(skb); dhr->dccph_reset_code = dcb->dccpd_reset_code; switch (dcb->dccpd_reset_code) { case DCCP_RESET_CODE_PACKET_ERROR: dhr->dccph_reset_data[0] = rxdh->dccph_type; break; case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */ case DCCP_RESET_CODE_MANDATORY_ERROR: memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3); break; } /* * From RFC 4340, 8.3.1: * If P.ackno exists, set R.seqno := P.ackno + 1. * Else set R.seqno := 0. */ if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1)); dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq); dccp_csum_outgoing(skb); return skb; }
/* * All SKB's seen here are completely headerless. It is our * job to build the DCCP header, and pass the packet down to * IP so it can do the same plus pass the packet off to the * device. */ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) { if (likely(skb != NULL)) { struct inet_sock *inet = inet_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); struct dccp_sock *dp = dccp_sk(sk); struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); struct dccp_hdr *dh; /* XXX For now we're using only 48 bits sequence numbers */ const u32 dccp_header_size = sizeof(*dh) + sizeof(struct dccp_hdr_ext) + dccp_packet_hdr_len(dcb->dccpd_type); int err, set_ack = 1; u64 ackno = dp->dccps_gsr; /* * Increment GSS here already in case the option code needs it. * Update GSS for real only if option processing below succeeds. */ dcb->dccpd_seq = ADD48(dp->dccps_gss, 1); switch (dcb->dccpd_type) { case DCCP_PKT_DATA: set_ack = 0; /* fall through */ case DCCP_PKT_DATAACK: case DCCP_PKT_RESET: break; case DCCP_PKT_REQUEST: set_ack = 0; /* Use ISS on the first (non-retransmitted) Request. */ if (icsk->icsk_retransmits == 0) dcb->dccpd_seq = dp->dccps_iss; /* fall through */ case DCCP_PKT_SYNC: case DCCP_PKT_SYNCACK: ackno = dcb->dccpd_ack_seq; /* fall through */ default: /* * Set owner/destructor: some skbs are allocated via * alloc_skb (e.g. when retransmission may happen). * Only Data, DataAck, and Reset packets should come * through here with skb->sk set. */ WARN_ON(skb->sk); skb_set_owner_w(skb, sk); break; } if (dccp_insert_options(sk, skb)) { kfree_skb(skb); return -EPROTO; } /* Build DCCP header and checksum it. */ dh = dccp_zeroed_hdr(skb, dccp_header_size); dh->dccph_type = dcb->dccpd_type; dh->dccph_sport = inet->inet_sport; dh->dccph_dport = inet->inet_dport; dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; dh->dccph_ccval = dcb->dccpd_ccval; dh->dccph_cscov = dp->dccps_pcslen; /* XXX For now we're using only 48 bits sequence numbers */ dh->dccph_x = 1; dccp_update_gss(sk, dcb->dccpd_seq); dccp_hdr_set_seq(dh, dp->dccps_gss); if (set_ack) dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); switch (dcb->dccpd_type) { case DCCP_PKT_REQUEST: dccp_hdr_request(skb)->dccph_req_service = dp->dccps_service; /* * Limit Ack window to ISS <= P.ackno <= GSS, so that * only Responses to Requests we sent are considered. */ dp->dccps_awl = dp->dccps_iss; break; case DCCP_PKT_RESET: dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code; break; } icsk->icsk_af_ops->send_check(sk, skb); if (set_ack) dccp_event_ack_sent(sk); DCCP_INC_STATS(DCCP_MIB_OUTSEGS); err = icsk->icsk_af_ops->queue_xmit(skb, &inet->cork.fl); return net_xmit_eval(err); } return -ENOBUFS; }
static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) { if (likely(skb != NULL)) { const struct inet_sock *inet = inet_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); struct dccp_sock *dp = dccp_sk(sk); struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); struct dccp_hdr *dh; const u32 dccp_header_size = sizeof(*dh) + sizeof(struct dccp_hdr_ext) + dccp_packet_hdr_len(dcb->dccpd_type); int err, set_ack = 1; u64 ackno = dp->dccps_gsr; dcb->dccpd_seq = ADD48(dp->dccps_gss, 1); switch (dcb->dccpd_type) { case DCCP_PKT_DATA: set_ack = 0; case DCCP_PKT_DATAACK: case DCCP_PKT_RESET: break; case DCCP_PKT_REQUEST: set_ack = 0; if (icsk->icsk_retransmits == 0) dcb->dccpd_seq = dp->dccps_iss; case DCCP_PKT_SYNC: case DCCP_PKT_SYNCACK: ackno = dcb->dccpd_ack_seq; default: WARN_ON(skb->sk); skb_set_owner_w(skb, sk); break; } if (dccp_insert_options(sk, skb)) { kfree_skb(skb); return -EPROTO; } dh = dccp_zeroed_hdr(skb, dccp_header_size); dh->dccph_type = dcb->dccpd_type; dh->dccph_sport = inet->sport; dh->dccph_dport = inet->dport; dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; dh->dccph_ccval = dcb->dccpd_ccval; dh->dccph_cscov = dp->dccps_pcslen; dh->dccph_x = 1; dccp_update_gss(sk, dcb->dccpd_seq); dccp_hdr_set_seq(dh, dp->dccps_gss); if (set_ack) dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); switch (dcb->dccpd_type) { case DCCP_PKT_REQUEST: dccp_hdr_request(skb)->dccph_req_service = dp->dccps_service; dp->dccps_awl = dp->dccps_iss; break; case DCCP_PKT_RESET: dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code; break; } icsk->icsk_af_ops->send_check(sk, 0, skb); if (set_ack) dccp_event_ack_sent(sk); DCCP_INC_STATS(DCCP_MIB_OUTSEGS); err = icsk->icsk_af_ops->queue_xmit(skb, 0); return net_xmit_eval(err); } return -ENOBUFS; }