Split out a more generic debugnet(4) from netdump(4)

Debugnet is a simplistic and specialized panic- or debug-time reliable
datagram transport.  It can drive a single connection at a time and is
currently unidirectional (debug/panic machine transmit to remote server
only).

It is mostly a verbatim code lift from netdump(4).  Netdump(4) remains
the only consumer (until the rest of this patch series lands).

The INET-specific logic has been extracted somewhat more thoroughly than
previously in netdump(4), into debugnet_inet.c.  UDP-layer logic and up, as
much as possible as is protocol-independent, remains in debugnet.c.  The
separation is not perfect and future improvement is welcome.  Supporting
INET6 is a long-term goal.

Much of the diff is "gratuitous" renaming from 'netdump_' or 'nd_' to
'debugnet_' or 'dn_' -- sorry.  I thought keeping the netdump name on the
generic module would be more confusing than the refactoring.

The only functional change here is the mbuf allocation / tracking.  Instead
of initiating solely on netdump-configured interface(s) at dumpon(8)
configuration time, we watch for any debugnet-enabled NIC for link
activation and query it for mbuf parameters at that time.  If they exceed
the existing high-water mark allocation, we re-allocate and track the new
high-water mark.  Otherwise, we leave the pre-panic mbuf allocation alone.
In a future patch in this series, this will allow initiating netdump from
panic ddb(4) without pre-panic configuration.

No other functional change intended.

Reviewed by:	markj (earlier version)
Some discussion with:	emaste, jhb
Objection from:	marius
Differential Revision:	https://reviews.freebsd.org/D21421

1 files changed, 91 insertions, 0 deletions

diff --git a/sys/net/debugnet_int.h b/sys/net/debugnet_int.h
new file mode 100644
index 000000000000..0dd206cf6761
--- /dev/null
+++ b/sys/net/debugnet_int.h
@@ -0,0 +1,91 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Isilon Systems, LLC.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#pragma once
+
+#ifndef DEBUGNET_INTERNAL
+#error "Don't include this"
+#endif
+
+#define	DNETDEBUG(f, ...) do {						\
+	if (debugnet_debug > 0)						\
+		printf(("%s: " f), __func__, ## __VA_ARGS__);		\
+} while (0)
+#define	DNETDEBUG_IF(i, f, ...) do {					\
+	if (debugnet_debug > 0)						\
+		if_printf((i), ("%s: " f), __func__, ## __VA_ARGS__);	\
+} while (0)
+#define	DNETDEBUGV(f, ...) do {						\
+	if (debugnet_debug > 1)						\
+		printf(("%s: " f), __func__, ## __VA_ARGS__);		\
+} while (0)
+
+enum dnet_pcb_st {
+	DN_STATE_INIT = 1,
+	DN_STATE_HAVE_GW_MAC,
+	DN_STATE_GOT_HERALD_PORT,
+};
+
+struct debugnet_pcb {
+	uint64_t		dp_rcvd_acks;
+
+	in_addr_t		dp_client;
+	in_addr_t		dp_server;
+	in_addr_t		dp_gateway;
+	uint32_t		dp_seqno;
+
+	struct ether_addr	dp_gw_mac;
+	uint16_t		dp_server_port;
+
+	struct ifnet		*dp_ifp;
+	/* Saved driver if_input to restore on close. */
+	void			(*dp_drv_input)(struct ifnet *, struct mbuf *);
+
+	enum dnet_pcb_st	dp_state;
+	uint16_t		dp_client_ack_port;
+};
+
+/* TODO(CEM): Obviate this assertion by using a BITSET(9) for acks. */
+CTASSERT(sizeof(((struct debugnet_pcb *)0)->dp_rcvd_acks) * NBBY >=
+    DEBUGNET_MAX_IN_FLIGHT);
+
+extern unsigned debugnet_debug;
+SYSCTL_DECL(_net_debugnet);
+
+int debugnet_ether_output(struct mbuf *, struct ifnet *, struct ether_addr,
+    u_short);
+void debugnet_handle_udp(struct debugnet_pcb *, struct mbuf **);
+void debugnet_network_poll(struct ifnet *);
+
+#ifdef INET
+int debugnet_arp_gw(struct debugnet_pcb *);
+void debugnet_handle_arp(struct debugnet_pcb *, struct mbuf **);
+void debugnet_handle_ip(struct debugnet_pcb *, struct mbuf **);
+int debugnet_ip_output(struct debugnet_pcb *, struct mbuf *);
+#endif