+
+/*
+ * Insert segment ti into reassembly queue of tcp with
+ * control block tp. Return TH_FIN if reassembly now includes
+ * a segment with FIN. The macro form does the common case inline
+ * (segment is the next to be received on an established connection,
+ * and the queue is empty), avoiding linkage into and removal
+ * from the queue and repetition of various conversions.
+ */
+#define TCP_REASS(tp, ti, m, so, flags) { \
+ if ((ti)->ti_seq == (tp)->rcv_nxt && \
+ (tp)->seg_next == (struct tcpiphdr *)(tp) && \
+ (tp)->t_state == TCPS_ESTABLISHED) { \
+ (tp)->rcv_nxt += (ti)->ti_len; \
+ flags = (ti)->ti_flags & TH_FIN; \
+ sbappend(&(so)->so_rcv, (m)); \
+ sorwakeup(so); \
+ } else \
+ (flags) = tcp_reass((tp), (ti)); \
+}
+
+tcp_reass(tp, ti)
+ register struct tcpcb *tp;
+ register struct tcpiphdr *ti;
+{
+ register struct tcpiphdr *q;
+ struct socket *so = tp->t_inpcb->inp_socket;
+ struct mbuf *m;
+ int flags;
+
+ /*
+ * Call with ti==0 after become established to
+ * force pre-ESTABLISHED data up to user socket.
+ */
+ if (ti == 0)
+ goto present;
+
+ /*
+ * Find a segment which begins after this one does.
+ */
+ for (q = tp->seg_next; q != (struct tcpiphdr *)tp;
+ q = (struct tcpiphdr *)q->ti_next)
+ if (SEQ_GT(q->ti_seq, ti->ti_seq))
+ break;
+
+ /*
+ * If there is a preceding segment, it may provide some of
+ * our data already. If so, drop the data from the incoming
+ * segment. If it provides all of our data, drop us.
+ */
+ if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) {
+ register int i;
+ q = (struct tcpiphdr *)q->ti_prev;
+ /* conversion to int (in i) handles seq wraparound */
+ i = q->ti_seq + q->ti_len - ti->ti_seq;
+ if (i > 0) {
+ if (i >= ti->ti_len)
+ goto drop;
+ m_adj(dtom(ti), i);
+ ti->ti_len -= i;
+ ti->ti_seq += i;
+ }
+ q = (struct tcpiphdr *)(q->ti_next);
+ }
+
+ /*
+ * While we overlap succeeding segments trim them or,
+ * if they are completely covered, dequeue them.
+ */
+ while (q != (struct tcpiphdr *)tp) {
+ register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
+ if (i <= 0)
+ break;
+ if (i < q->ti_len) {
+ q->ti_seq += i;
+ q->ti_len -= i;
+ m_adj(dtom(q), i);
+ break;
+ }
+ q = (struct tcpiphdr *)q->ti_next;
+ m = dtom(q->ti_prev);
+ remque(q->ti_prev);
+ m_freem(m);
+ }
+
+ /*
+ * Stick new segment in its place.
+ */
+ insque(ti, q->ti_prev);
+
+present:
+ /*
+ * Present data to user, advancing rcv_nxt through
+ * completed sequence space.
+ */
+ if (TCPS_HAVERCVDSYN(tp->t_state) == 0)
+ return (0);
+ ti = tp->seg_next;
+ if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt)
+ return (0);
+ if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
+ return (0);
+ do {
+ tp->rcv_nxt += ti->ti_len;
+ flags = ti->ti_flags & TH_FIN;
+ remque(ti);
+ m = dtom(ti);
+ ti = (struct tcpiphdr *)ti->ti_next;
+ if (so->so_state & SS_CANTRCVMORE)
+ m_freem(m);
+ else
+ sbappend(&so->so_rcv, m);
+ } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
+ sorwakeup(so);
+ return (flags);
+drop:
+ m_freem(dtom(ti));
+ return (0);
+}
+
projects / unix-history / blobdiff