aboutgitcodebugslistschat
path: root/tap.c
diff options
context:
space:
mode:
authorDavid Gibson <david@gibson.dropbear.id.au>2024-03-08 17:53:24 +1100
committerStefano Brivio <sbrivio@redhat.com>2024-03-14 16:57:37 +0100
commit4db947d17c8c7dac3b344c8ce0a266f7be159200 (patch)
tree5db310fa193a86befdf4df2ff940aa6aeed59f82 /tap.c
parent1ebe787fe460eb83d67792b6af1b02f4f555dc86 (diff)
downloadpasst-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar.gz
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar.bz2
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar.lz
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar.xz
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.tar.zst
passt-4db947d17c8c7dac3b344c8ce0a266f7be159200.zip
tap: Implement tap_send() "slow path" in terms of fast path
Most times we send frames to the guest it goes via tap_send_frames(). However "slow path" protocols - ARP, ICMP, ICMPv6, DHCP and DHCPv6 - go via tap_send(). As well as being a semantic duplication, tap_send() contains at least one serious problem: it doesn't properly handle short sends, which can be fatal on the qemu socket connection, since frame boundaries will get out of sync. Rewrite tap_send() to call tap_send_frames(). While we're there, rename it tap_send_single() for clarity. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Diffstat (limited to 'tap.c')
-rw-r--r--tap.c38
1 files changed, 17 insertions, 21 deletions
diff --git a/tap.c b/tap.c
index b6cc14c..13e4da7 100644
--- a/tap.c
+++ b/tap.c
@@ -67,28 +67,28 @@ static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS, pkt_buf);
#define FRAGMENT_MSG_RATE 10 /* # seconds between fragment warnings */
/**
- * tap_send() - Send frame, with qemu socket header if needed
+ * tap_send_single() - Send a single frame
* @c: Execution context
* @data: Packet buffer
* @len: Total L2 packet length
- *
- * Return: return code from send() or write()
*/
-int tap_send(const struct ctx *c, const void *data, size_t len)
+void tap_send_single(const struct ctx *c, const void *data, size_t len)
{
- pcap(data, len);
+ uint32_t vnet_len = htonl(len);
+ struct iovec iov[2];
+ size_t iovcnt = 0;
if (c->mode == MODE_PASST) {
- int flags = MSG_NOSIGNAL | MSG_DONTWAIT;
- uint32_t vnet_len = htonl(len);
-
- if (send(c->fd_tap, &vnet_len, 4, flags) < 0)
- return -1;
-
- return send(c->fd_tap, data, len, flags);
+ iov[iovcnt].iov_base = &vnet_len;
+ iov[iovcnt].iov_len = sizeof(vnet_len);
+ iovcnt++;
}
- return write(c->fd_tap, (char *)data, len);
+ iov[iovcnt].iov_base = (void *)data;
+ iov[iovcnt].iov_len = len;
+ iovcnt++;
+
+ tap_send_frames(c, iov, iovcnt, 1);
}
/**
@@ -189,8 +189,7 @@ void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
csum_udp4(uh, src, dst, in, len);
memcpy(data, in, len);
- if (tap_send(c, buf, len + (data - buf)) < 0)
- debug("tap: failed to send %zu bytes (IPv4)", len);
+ tap_send_single(c, buf, len + (data - buf));
}
/**
@@ -212,8 +211,7 @@ void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
memcpy(icmp4h, in, len);
csum_icmp4(icmp4h, icmp4h + 1, len - sizeof(*icmp4h));
- if (tap_send(c, buf, len + ((char *)icmp4h - buf)) < 0)
- debug("tap: failed to send %zu bytes (IPv4)", len);
+ tap_send_single(c, buf, len + ((char *)icmp4h - buf));
}
/**
@@ -274,8 +272,7 @@ void tap_udp6_send(const struct ctx *c,
csum_udp6(uh, src, dst, in, len);
memcpy(data, in, len);
- if (tap_send(c, buf, len + (data - buf)) < 1)
- debug("tap: failed to send %zu bytes (IPv6)", len);
+ tap_send_single(c, buf, len + (data - buf));
}
/**
@@ -298,8 +295,7 @@ void tap_icmp6_send(const struct ctx *c,
memcpy(icmp6h, in, len);
csum_icmp6(icmp6h, src, dst, icmp6h + 1, len - sizeof(*icmp6h));
- if (tap_send(c, buf, len + ((char *)icmp6h - buf)) < 1)
- debug("tap: failed to send %zu bytes (IPv6)", len);
+ tap_send_single(c, buf, len + ((char *)icmp6h - buf));
}
/**