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ofpbuf: Abstract 'l2' pointer and document usage conventions.

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Rename 'l2' to 'frame' and add new ofpbuf_set_frame() and ofpbuf_l2().
ofpbuf_set_frame() alse resets all the layer offsets.  ofpbuf_l2()
returns NULL if the packet has no Ethernet header, as indicated either
by unset l3 offset or NULL frame pointer.  Callers of ofpbuf_l2() are
supposed to check the return value, unless they can otherwise be sure
that the packet has a valid Ethernet header.

The recent commit 437d0d22 made some assumptions that were not valid
regarding the use of the 'l2' pointer in rconn module and by
compose_rarp().  This is now fixed as follows: rconn now relies on the
fact that once OpenFlow messages are given to rconn for transport, the
frame pointer is no longer needed to refer to the OpenFlow header; and
compose_rarp() now sets the frame pointer and offsets as expected.

In addition to storing network frames, ofpbufs are also used for
handling OpenFlow messages and action lists.  lib/ofpbuf.h now has a
comment documenting the current usage conventions and invariants.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Jarno Rajahalme
2014-04-02 15:44:21 -07:00
parent 6b8c377a6e
commit cf3b753866
16 changed files with 164 additions and 127 deletions
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7
lib/flow.c
View File

@@ -371,10 +371,7 @@ flow_extract(struct ofpbuf *packet, const struct pkt_metadata *md,
flow->pkt_mark = md->pkt_mark;
}
packet->l2 = ofpbuf_data(&b);
ofpbuf_set_l2_5(packet, NULL);
ofpbuf_set_l3(packet, NULL);
ofpbuf_set_l4(packet, NULL);
ofpbuf_set_frame(packet, ofpbuf_data(packet));
if (ofpbuf_size(&b) < sizeof *eth) {
return;
@@ -1330,7 +1327,7 @@ flow_compose(struct ofpbuf *b, const struct flow *flow)
/* eth_compose() sets l3 pointer and makes sure it is 32-bit aligned. */
eth_compose(b, flow->dl_dst, flow->dl_src, ntohs(flow->dl_type), 0);
if (flow->dl_type == htons(FLOW_DL_TYPE_NONE)) {
struct eth_header *eth = b->l2;
struct eth_header *eth = ofpbuf_l2(b);
eth->eth_type = htons(ofpbuf_size(b));
return;
}