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packets: Reserve headroom for VLAN header in eth_compose(), snap_compose().

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This allows callers to add a VLAN header to the composed packet and send
it out on a VLAN without copying the whole payload.
This commit is contained in:
Ben Pfaff
2011-03-29 09:28:49 -07:00
parent 7c66b273a2
commit eda1f38d41
1 changed files with 13 additions and 4 deletions
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17
lib/packets.c
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@@ -221,7 +221,10 @@ ipv6_is_cidr(const struct in6_addr *netmask)
/* Populates 'b' with an Ethernet II packet headed with the given 'eth_dst', /* Populates 'b' with an Ethernet II packet headed with the given 'eth_dst',
* 'eth_src' and 'eth_type' parameters. A payload of 'size' bytes is allocated * 'eth_src' and 'eth_type' parameters. A payload of 'size' bytes is allocated
* in 'b' and returned. This payload may be populated with appropriate * in 'b' and returned. This payload may be populated with appropriate
* information by the caller. */ * information by the caller.
*
* The returned packet has enough headroom to insert an 802.1Q VLAN header if
* desired. */
void * void *
eth_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN], eth_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
const uint8_t eth_src[ETH_ADDR_LEN], uint16_t eth_type, const uint8_t eth_src[ETH_ADDR_LEN], uint16_t eth_type,
@@ -232,7 +235,8 @@ eth_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
ofpbuf_clear(b); ofpbuf_clear(b);
ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + size); ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + VLAN_HEADER_LEN + size);
ofpbuf_reserve(b, VLAN_HEADER_LEN);
eth = ofpbuf_put_uninit(b, ETH_HEADER_LEN); eth = ofpbuf_put_uninit(b, ETH_HEADER_LEN);
data = ofpbuf_put_uninit(b, size); data = ofpbuf_put_uninit(b, size);
@@ -246,7 +250,10 @@ eth_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
/* Populates 'b' with an Ethernet LLC+SNAP packet headed with the given /* Populates 'b' with an Ethernet LLC+SNAP packet headed with the given
* 'eth_dst', 'eth_src', 'snap_org', and 'snap_type'. A payload of 'size' * 'eth_dst', 'eth_src', 'snap_org', and 'snap_type'. A payload of 'size'
* bytes is allocated in 'b' and returned. This payload may be populated with * bytes is allocated in 'b' and returned. This payload may be populated with
* appropriate information by the caller. */ * appropriate information by the caller.
*
* The returned packet has enough headroom to insert an 802.1Q VLAN header if
* desired. */
void * void *
snap_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN], snap_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
const uint8_t eth_src[ETH_ADDR_LEN], const uint8_t eth_src[ETH_ADDR_LEN],
@@ -259,7 +266,9 @@ snap_compose(struct ofpbuf *b, const uint8_t eth_dst[ETH_ADDR_LEN],
/* Compose basic packet structure. (We need the payload size to stick into /* Compose basic packet structure. (We need the payload size to stick into
* the 802.2 header.) */ * the 802.2 header.) */
ofpbuf_clear(b); ofpbuf_clear(b);
ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + LLC_SNAP_HEADER_LEN + size); ofpbuf_prealloc_tailroom(b, ETH_HEADER_LEN + VLAN_HEADER_LEN
+ LLC_SNAP_HEADER_LEN + size);
ofpbuf_reserve(b, VLAN_HEADER_LEN);
eth = ofpbuf_put_zeros(b, ETH_HEADER_LEN); eth = ofpbuf_put_zeros(b, ETH_HEADER_LEN);
llc_snap = ofpbuf_put_zeros(b, LLC_SNAP_HEADER_LEN); llc_snap = ofpbuf_put_zeros(b, LLC_SNAP_HEADER_LEN);
payload = ofpbuf_put_uninit(b, size); payload = ofpbuf_put_uninit(b, size);