treewide: Standardise variable names for various packet lengths

At various points we need to track the lengths of a packet including or
excluding various different sets of headers.  We don't always use the same
variable names for doing so.  Worse in some places we use the same name
for different things: e.g. tcp_fill_headers[46]() use ip_len for the
length including the IP headers, but then tcp_send_flag() which calls it
uses it to mean the IP payload length only.

To improve clarity, standardise on these names:
   dlen:		L4 protocol payload length ("data length")
   l4len:		plen + length of L4 protocol header
   l3len:		l4len + length of IPv4/IPv6 header
   l2len:		l3len + length of L2 (ethernet) header

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/dhcp.c b/dhcp.c
index ff4834a..aa9f59d 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -275,7 +275,7 @@ static void opt_set_dns_search(const struct ctx *c, size_t max_len)
  */
 int dhcp(const struct ctx *c, const struct pool *p)
 {
-	size_t mlen, len, offset = 0, opt_len, opt_off = 0;
+	size_t mlen, dlen, offset = 0, opt_len, opt_off = 0;
 	const struct ethhdr *eh;
 	const struct iphdr *iph;
 	const struct udphdr *uh;
@@ -377,8 +377,8 @@ int dhcp(const struct ctx *c, const struct pool *p)
 	if (!c->no_dhcp_dns_search)
 		opt_set_dns_search(c, sizeof(m->o));
 
-	len = offsetof(struct msg, o) + fill(m);
-	tap_udp4_send(c, c->ip4.gw, 67, c->ip4.addr, 68, m, len);
+	dlen = offsetof(struct msg, o) + fill(m);
+	tap_udp4_send(c, c->ip4.gw, 67, c->ip4.addr, 68, m, dlen);
 
 	return 1;
 }