clj-ebpf.net.tcp — org.clojars.pgdad/clj-ebpf 0.3.0

TCP packet parsing and manipulation helpers for eBPF programs.

get-payload-ptr clj

(get-payload-ptr payload-reg tcp-hdr-reg tcp-hlen-reg)

Calculate pointer to TCP payload. Requires knowing TCP header length (data offset).

payload-reg: Register to store payload pointer tcp-hdr-reg: Register pointing to TCP header tcp-hlen-reg: Register containing TCP header length in bytes

is-ack clj

(is-ack flags-reg ack-label)

Check if TCP ACK flag is set.

flags-reg: Register containing TCP flags ack-label: Label offset to jump to if ACK

is-dport clj

(is-dport dport-reg port match-label)

Check if destination port matches (network byte order comparison).

dport-reg: Register containing destination port (network order) port: Port number (will be converted to network order) match-label: Label to jump to if ports match

is-fin clj

(is-fin flags-reg fin-label)

Check if TCP FIN flag is set.

flags-reg: Register containing TCP flags fin-label: Label offset to jump to if FIN

is-psh clj

(is-psh flags-reg psh-label)

Check if TCP PSH flag is set.

flags-reg: Register containing TCP flags psh-label: Label offset to jump to if PSH

is-rst clj

(is-rst flags-reg rst-label)

Check if TCP RST flag is set.

flags-reg: Register containing TCP flags rst-label: Label offset to jump to if RST

is-sport clj

(is-sport sport-reg port match-label)

Check if source port matches (network byte order comparison).

sport-reg: Register containing source port (network order) port: Port number (will be converted to network order) match-label: Label to jump to if ports match

is-syn clj

(is-syn flags-reg syn-label)

Check if TCP SYN flag is set. Jumps to syn-label if SYN is set, falls through otherwise.

flags-reg: Register containing TCP flags syn-label: Label offset to jump to if SYN

is-syn-ack clj

(is-syn-ack flags-reg scratch-reg syn-ack-label)

Check if SYN and ACK flags are both set.

flags-reg: Register containing TCP flags scratch-reg: Scratch register syn-ack-label: Label offset to jump to if SYN+ACK

is-syn-only clj

(is-syn-only flags-reg scratch-reg syn-only-label)

Check if only SYN flag is set (connection initiation). Jumps to syn-only-label if SYN is set and ACK is not.

flags-reg: Register containing TCP flags scratch-reg: Scratch register syn-only-label: Label offset to jump to if SYN-only

load-ack-seq clj

(load-ack-seq dst-reg tcp-hdr-reg)

Load TCP acknowledgment number into dst-reg (network byte order).

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-data-offset clj

(load-data-offset dst-reg tcp-hdr-reg)

Load TCP data offset (header length in 32-bit words) into dst-reg.

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-dport clj

(load-dport dst-reg tcp-hdr-reg)

Load TCP destination port into dst-reg (network byte order).

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-field clj

(load-field dst-reg tcp-hdr-reg field size)

Load a TCP header field into dst-reg.

dst-reg: Destination register tcp-hdr-reg: Register pointing to start of TCP header field: Field keyword (:sport, :dport, :seq, etc.) size: :b (byte), :h (half-word), :w (word)

load-flags clj

(load-flags dst-reg tcp-hdr-reg)

Load TCP flags byte into register.

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-header-len clj

(load-header-len dst-reg tcp-hdr-reg)

Load TCP header length in bytes into dst-reg.

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-ports clj

(load-ports sport-reg dport-reg tcp-hdr-reg)

Load TCP source and destination ports. Ports are loaded in network byte order.

sport-reg: Register for source port dport-reg: Register for destination port tcp-hdr-reg: Register pointing to TCP header

load-ports-host clj

(load-ports-host sport-reg dport-reg tcp-hdr-reg)

Load TCP source and destination ports in host byte order.

sport-reg: Register for source port (host order) dport-reg: Register for destination port (host order) tcp-hdr-reg: Register pointing to TCP header

load-seq clj

(load-seq dst-reg tcp-hdr-reg)

Load TCP sequence number into dst-reg (network byte order).

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-sport clj

(load-sport dst-reg tcp-hdr-reg)

Load TCP source port into dst-reg (network byte order).

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

load-window clj

(load-window dst-reg tcp-hdr-reg)

Load TCP window size into dst-reg (network byte order).

dst-reg: Destination register tcp-hdr-reg: Register pointing to TCP header

parse-tcp-header clj

(parse-tcp-header tcp-hdr-reg
                  data-end-reg
                  sport-reg
                  dport-reg
                  fail-label
                  scratch-reg)

Parse TCP header and check bounds. Returns instructions that:

1. Check bounds for minimum TCP header (20 bytes)
2. Load source and destination ports

tcp-hdr-reg: Register pointing to TCP header start data-end-reg: Register containing data_end pointer sport-reg: Register to store source port dport-reg: Register to store destination port fail-label: Label to jump to on bounds failure scratch-reg: Scratch register for bounds check

store-dport clj

(store-dport tcp-hdr-reg port-reg)

Store TCP destination port (expects network byte order).

tcp-hdr-reg: Register pointing to TCP header port-reg: Register containing port (network order)

store-field clj

(store-field tcp-hdr-reg field src-reg size)

Store value to TCP header field.

tcp-hdr-reg: Register pointing to TCP header start field: Field keyword src-reg: Register containing value to store size: :b, :h, or :w

store-port-host clj

(store-port-host tcp-hdr-reg field port-reg scratch-reg)

Store TCP port from host byte order value.

tcp-hdr-reg: Register pointing to TCP header field: :sport or :dport port-reg: Register containing port (host order) scratch-reg: Scratch register for byte order conversion

store-sport clj

(store-sport tcp-hdr-reg port-reg)

Store TCP source port (expects network byte order).

tcp-hdr-reg: Register pointing to TCP header port-reg: Register containing port (network order)