clj-ebpf.tc — org.clojars.pgdad/clj-ebpf 0.1.1

TC (Traffic Control) support for BPF packet filtering and QoS

add-clsact-qdisc clj

(add-clsact-qdisc ifname)

Add clsact qdisc to a network interface.

The clsact qdisc is required before attaching TC BPF programs. It provides ingress and egress attachment points.

Parameters:

• ifname: Interface name (e.g., "eth0") or interface index (integer)

Returns the interface index.

Example: (add-clsact-qdisc "eth0")

attach-tc-filter clj

(attach-tc-filter ifname
                  prog-fd
                  direction
                  &
                  {:keys [prog-name priority auto-qdisc]
                   :or {prog-name "tc_bpf" priority 1 auto-qdisc true}})

Attach TC BPF program as a filter on a network interface.

Parameters:

• ifname: Interface name (e.g., "eth0") or interface index (integer)
• prog-fd: BPF program file descriptor
• direction: :ingress or :egress
• options: Map of options:
  • :prog-name - Program name for identification (default "tc_bpf")
  • :priority - Filter priority (default 1, lower = higher priority)
  • :auto-qdisc - Automatically add clsact qdisc if needed (default true)

Returns a map with :ifindex and :direction for use with detach-tc-filter.

Example: (attach-tc-filter "eth0" prog-fd :ingress {:prog-name "my_filter" :priority 1})

detach-tc-filter clj

(detach-tc-filter ifname direction priority)

Detach TC BPF filter from a network interface.

Parameters:

• ifname: Interface name (e.g., "eth0") or interface index (integer)
• direction: :ingress or :egress
• priority: Filter priority (must match the one used in attach-tc-filter)

Example: (detach-tc-filter "eth0" :ingress 1)

Or using the attachment info: (let [info (attach-tc-filter "eth0" prog-fd :ingress)] (detach-tc-filter (:ifindex info) (:direction info) (:priority info)))

int->tc-action clj

load-tc-program clj

(load-tc-program bytecode
                 prog-type
                 &
                 {:keys [prog-name license log-level log-size]
                  :or {license "GPL" log-level 0 log-size 0}})

Load TC BPF program from bytecode.

Parameters:

• bytecode: BPF bytecode (byte array or vector of instruction maps)
• prog-type: Program type (:sched-cls or :sched-act)
• options: Map of options:
  • :prog-name - Program name (optional)
  • :license - License string (default "GPL")
  • :log-level - Verifier log level (default 0)
  • :log-size - Log buffer size (default 0)

Returns program file descriptor.

Example: (load-tc-program bytecode :sched-cls {:prog-name "tc_filter" :license "GPL"})

remove-clsact-qdisc clj

(remove-clsact-qdisc ifname)

Remove clsact qdisc from a network interface.

This will also remove all attached TC BPF filters.

Parameters:

• ifname: Interface name (e.g., "eth0") or interface index (integer)

Example: (remove-clsact-qdisc "eth0")

setup-tc-egress clj

(setup-tc-egress ifname
                 bytecode
                 &
                 {:keys [prog-name priority]
                  :or {prog-name "tc_egress" priority 1}
                  :as options})

Setup TC BPF filter on egress (outgoing packets).

Similar to setup-tc-ingress but for outgoing traffic.

Example: (def setup (setup-tc-egress "eth0" bytecode {:prog-name "egress_filter"}))

setup-tc-ingress clj

(setup-tc-ingress ifname
                  bytecode
                  &
                  {:keys [prog-name priority]
                   :or {prog-name "tc_ingress" priority 1}
                   :as options})

Setup TC BPF filter on ingress (incoming packets).

Convenience function that:

1. Adds clsact qdisc if needed
2. Loads the BPF program
3. Attaches it to ingress

Parameters:

• ifname: Interface name
• bytecode: BPF bytecode
• options: Program and filter options

Returns a map with :prog-fd and :filter-info for cleanup.

Example: (def setup (setup-tc-ingress "eth0" bytecode {:prog-name "ingress_filter"})) ;; ... later ... (teardown-tc-filter setup)

tc-action clj

tc-action->int clj

tc-direction clj

teardown-tc-filter clj

(teardown-tc-filter {:keys [prog-fd filter-info]})

Teardown TC filter setup created by setup-tc-ingress or setup-tc-egress.

Parameters:

• setup: Map returned by setup-tc-ingress/egress with :prog-fd and :filter-info

Example: (teardown-tc-filter setup)

with-tc-filter clj macro

(with-tc-filter [binding attach-expr] & body)

Attach TC filter and ensure detachment after use.

Example: (with-tc-filter [info (attach-tc-filter "eth0" prog-fd :ingress {:priority 1})] ;; TC filter is active (do-packet-processing))

with-tc-program clj macro

(with-tc-program [prog-binding bytecode prog-type options iface-binding ifname
                  direction filter-options]
                 &
                 body)

Load TC program, attach filter, and ensure cleanup.

Example: (with-tc-program [prog-fd bytecode :sched-cls {:prog-name "tc_filter"} info "eth0" :ingress {:priority 1}] ;; TC program is loaded and attached (process-packets))