path: root/arp.c
diff options
authorStefano Brivio <sbrivio@redhat.com>2021-02-16 07:25:09 +0100
committerStefano Brivio <sbrivio@redhat.com>2021-02-16 09:28:55 +0100
commit105b916361ca6e9e63112444c323cc193303120c (patch)
tree4f21e30b721045f7ba3264c17d2e56a2a401ca1c /arp.c
parentd02e059ddcc00fba763c995818a5884ed8e97984 (diff)
passt: New design and implementation with native Layer 4 sockets
This is a reimplementation, partially building on the earlier draft, that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW, providing L4-L2 translation functionality without requiring any security capability. Conceptually, this follows the design presented at: https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md The most significant novelty here comes from TCP and UDP translation layers. In particular, the TCP state and translation logic follows the intent of being minimalistic, without reimplementing a full TCP stack in either direction, and synchronising as much as possible the TCP dynamic and flows between guest and host kernel. Another important introduction concerns addressing, port translation and forwarding. The Layer 4 implementations now attempt to bind on all unbound ports, in order to forward connections in a transparent way. While at it: - the qemu 'tap' back-end can't be used as-is by qrap anymore, because of explicit checks now introduced in qemu to ensure that the corresponding file descriptor is actually a tap device. For this reason, qrap now operates on a 'socket' back-end type, accounting for and building the additional header reporting frame length - provide a demo script that sets up namespaces, addresses and routes, and starts the daemon. A virtual machine started in the network namespace, wrapped by qrap, will now directly interface with passt and communicate using Layer 4 sockets provided by the host kernel. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Diffstat (limited to 'arp.c')
1 files changed, 8 insertions, 3 deletions
diff --git a/arp.c b/arp.c
index 3837a04..21b6417 100644
--- a/arp.c
+++ b/arp.c
@@ -1,9 +1,11 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
* arp.c - ARP implementation
+ * Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
- * License: GPLv2
@@ -23,6 +25,7 @@
#include "passt.h"
#include "dhcp.h"
#include "util.h"
+#include "tap.h"
* struct arpmsg - 802.2 ARP IPv4 payload
@@ -39,7 +42,7 @@ struct arpmsg {
} __attribute__((__packed__));
- * dhcp() - Check if this is an ARP message, reply as needed
+ * arp() - Check if this is an ARP message, reply as needed
* @c: Execution context
* @len: Total L2 packet length
* @eh: Packet buffer, Ethernet header
@@ -74,9 +77,11 @@ int arp(struct ctx *c, unsigned len, struct ethhdr *eh)
len = sizeof(*eh) + sizeof(*ah) + sizeof(*am);
memcpy(eh->h_dest, eh->h_source, ETH_ALEN);
+ /* HACK */
+ memcpy(c->mac_guest, eh->h_source, ETH_ALEN);
memcpy(eh->h_source, c->mac, ETH_ALEN);
- if (send(c->fd_unix, eh, len, 0) < 0)
+ if (tap_send(c->fd_unix, eh, len, 0) < 0)
perror("ARP: send");
return 1;