lib: Replace shim IPCPs with points of attachment

Removes the UDP and Ethernet shim IPCPs. The unicast and broadcast
IPCPs can now directly attach to a "legacy" socket. We adopt Saltzer's
Point-of-Attachment terminology, also advocated in Day's "Patterns in
Network Architecture". The "poa" component manages these
PoA's with one management thread, one link monitoring thread and one
thread per attached point.

For Ethernet PoA's the irm connect and enroll can resolve the
destination IPCP or Layer name with a broadcast name query over the
attached PoAs (first reply wins). UDP PoA's require a destination IP
address or FQDN.

attach to a local endpoint (required both server and client side):

 irm ipcp poa attach name a udp 10.0.0.1
 irm ipcp poa attach name a udp 10.0.0.1:3435
 irm ipcp poa attach name a udp [::1]:3435
 irm ipcp poa attach name a eth dev eth0
 irm ipcp poa attach name a eth dev eth0 ethertype 0xA000

release a PoA (refused while it carries a flow):

 irm ipcp poa detach name a udp 10.0.0.1:3435
 irm ipcp poa detach name a eth eth0

list an IPCP's PoAs:

 irm ipcp poa list name a

connect to a peer, by name or at an address:

 irm ipcp connect name b dst a
 irm ipcp connect name b dst a eth
 irm ipcp connect name b dst a eth dev eth0
 irm ipcp connect name b dst a udp 10.0.0.1:3435
 irm ipcp connect name b dst a udp peer.example.com:3435

disconnect by peer name, no address:

 irm ipcp disconnect name b dst a
 irm ipcp disconnect name b dst a component mgmt

enroll has the same shape as connect:

 irm ipcp enroll name b layer lr autobind
 irm ipcp enroll name b layer lr autobind eth dev eth0
 irm ipcp enroll name b layer lr autobind udp 10.0.0.1:3435

the IRMd config file attaches PoAs and names peers the same way:

 udp = [ "10.0.0.1", "10.0.0.1:3436" ]
 eth = [ "eth0", {dev="eth1", ethertype=0xA007} ]

 enrol={dst="LAN", eth={dev="eth0"}}
 conn=[{dst="lan3", eth={}}, {dst="lan4", udp="10.0.0.1:3435"}]

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 14 insertions, 10 deletions

diff --git a/cmake/dependencies/eth/netmap.cmake b/cmake/dependencies/eth/netmap.cmake
index 94ecd634..b31c4d03 100644
--- a/cmake/dependencies/eth/netmap.cmake
+++ b/cmake/dependencies/eth/netmap.cmake
@@ -1,18 +1,22 @@
-# netmap support (optional acceleration)
+# netmap support (kernel bypass). Explicit opt-in.
 find_path(NETMAP_C_INCLUDE_DIR
   net/netmap_user.h
   HINTS /usr/include /usr/local/include)
 
 mark_as_advanced(NETMAP_C_INCLUDE_DIR)
 
-if(NOT HAVE_RAW_SOCKETS AND NOT HAVE_BPF AND NETMAP_C_INCLUDE_DIR)
-  set(DISABLE_NETMAP FALSE CACHE BOOL
-    "Disable netmap support for ETH IPCPs")
-  if(NOT DISABLE_NETMAP)
-    message(STATUS "Netmap support for Ethernet IPCPs enabled")
-    set(HAVE_NETMAP TRUE)
-  else()
-    message(STATUS "Netmap support for Ethernet IPCPs disabled by user")
-    unset(HAVE_NETMAP)
+set(ENABLE_NETMAP FALSE CACHE BOOL
+  "Use netmap for Ethernet PoAs, overriding raw sockets or BPF")
+
+if(ENABLE_NETMAP)
+  if(NOT NETMAP_C_INCLUDE_DIR)
+    message(FATAL_ERROR "ENABLE_NETMAP is set, but netmap was not found.")
   endif()
+
+  message(STATUS "Netmap support for Ethernet PoAs enabled")
+
+  set(HAVE_NETMAP TRUE)
+
+  unset(HAVE_RAW_SOCKETS)
+  unset(HAVE_BPF)
 endif()