Callers of tap_send() can optionally use a small optimization by adding
extra space for the 4 byte length header used on the qemu socket interface.
tap_ip_send() is currently the only user of this, but this is used only
for "slow path" ICMP and DHCP packets, so there's not a lot of value to
the optimization.
Worse, having the two paths here complicates the interface and makes future
cleanups difficult, so just remove it. I have some plans to bring back the
optimization in a more general way in future, but for now it's just in the
way.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
arp.c | 2 +-
dhcp.c | 2 +-
ndp.c | 2 +-
tap.c | 29 +++++++++--------------------
tap.h | 2 +-
5 files changed, 13 insertions(+), 24 deletions(-)
diff --git a/arp.c b/arp.c
index 0ad97af..141d43f 100644
--- a/arp.c
+++ b/arp.c
@@ -81,7 +81,7 @@ int arp(const struct ctx *c, const struct pool *p)
memcpy(eh->h_dest, eh->h_source, sizeof(eh->h_dest));
memcpy(eh->h_source, c->mac, sizeof(eh->h_source));
- if (tap_send(c, eh, len, 0) < 0)
+ if (tap_send(c, eh, len) < 0)
perror("ARP: send");
return 1;
diff --git a/dhcp.c b/dhcp.c
index 875e18b..2b3af82 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -377,7 +377,7 @@ int dhcp(const struct ctx *c, const struct pool *p)
memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
memcpy(eh->h_source, c->mac, ETH_ALEN);
- if (tap_send(c, eh, len, 0) < 0)
+ if (tap_send(c, eh, len) < 0)
perror("DHCP: send");
return 1;
diff --git a/ndp.c b/ndp.c
index 03f1d06..79be0cf 100644
--- a/ndp.c
+++ b/ndp.c
@@ -200,7 +200,7 @@ dns_done:
memcpy(ehr->h_source, c->mac, ETH_ALEN);
ehr->h_proto = htons(ETH_P_IPV6);
- if (tap_send(c, ehr, len, 0) < 0)
+ if (tap_send(c, ehr, len) < 0)
perror("NDP: send");
return 1;
diff --git a/tap.c b/tap.c
index 3ad5d7c..ae75fac 100644
--- a/tap.c
+++ b/tap.c
@@ -66,34 +66,24 @@ static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS, pkt_buf);
* @c: Execution context
* @data: Packet buffer
* @len: Total L2 packet length
- * @vnet_pre: Buffer has four-byte headroom
*
* Return: return code from send() or write()
*/
-int tap_send(const struct ctx *c, const void *data, size_t len, int vnet_pre)
+int tap_send(const struct ctx *c, const void *data, size_t len)
{
- if (vnet_pre)
- pcap((char *)data + 4, len);
- else
- pcap(data, len);
+ pcap(data, len);
if (c->mode == MODE_PASST) {
int flags = MSG_NOSIGNAL | MSG_DONTWAIT;
+ uint32_t vnet_len = htonl(len);
- if (vnet_pre) {
- *((uint32_t *)data) = htonl(len);
- len += 4;
- } else {
- uint32_t vnet_len = htonl(len);
-
- if (send(c->fd_tap, &vnet_len, 4, flags) < 0)
- return -1;
- }
+ if (send(c->fd_tap, &vnet_len, 4, flags) < 0)
+ return -1;
return send(c->fd_tap, data, len, flags);
}
- return write(c->fd_tap, (char *)data + (vnet_pre ? 4 : 0), len);
+ return write(c->fd_tap, (char *)data, len);
}
/**
@@ -131,10 +121,9 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src,
uint8_t proto,
const char *in, size_t len, uint32_t flow)
{
char buf[USHRT_MAX];
- char *pkt = buf + 4;
struct ethhdr *eh;
- eh = (struct ethhdr *)pkt;
+ eh = (struct ethhdr *)buf;
/* TODO: ARP table lookup */
memcpy(eh->h_dest, c->mac_guest, ETH_ALEN);
@@ -170,7 +159,7 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src,
uint8_t proto,
csum_icmp4(ih, ih + 1, len - sizeof(*ih));
}
- if (tap_send(c, buf, len + sizeof(*iph) + sizeof(*eh), 1) < 0)
+ if (tap_send(c, buf, len + sizeof(*iph) + sizeof(*eh)) < 0)
debug("tap: failed to send %lu bytes (IPv4)", len);
} else {
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
@@ -211,7 +200,7 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src,
uint8_t proto,
ip6h->flow_lbl[2] = (flow >> 0) & 0xff;
}
- if (tap_send(c, buf, len + sizeof(*ip6h) + sizeof(*eh), 1) < 1)
+ if (tap_send(c, buf, len + sizeof(*ip6h) + sizeof(*eh)) < 1)
debug("tap: failed to send %lu bytes (IPv6)", len);
}
}
diff --git a/tap.h b/tap.h
index a6764b4..a8da8bb 100644
--- a/tap.h
+++ b/tap.h
@@ -11,7 +11,7 @@ const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
const struct in6_addr *src);
void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
const char *in, size_t len, uint32_t flow);
-int tap_send(const struct ctx *c, const void *data, size_t len, int vnet_pre);
+int tap_send(const struct ctx *c, const void *data, size_t len);
void tap_handler(struct ctx *c, int fd, uint32_t events,
const struct timespec *now);
void tap_sock_init(struct ctx *c);
--
2.37.3