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

Ethernet frame parsing and manipulation helpers for eBPF programs.

ETH-P-ARP-BE clj

ETH-P-IP-BE clj

ETH-P-IPV6-BE clj

get-ip-header-ptr clj

(get-ip-header-ptr ip-ptr-reg data-reg)

Calculate pointer to IP header (after Ethernet header).

ip-ptr-reg: Register to store IP header pointer data-reg: Register containing packet data pointer

is-arp clj

(is-arp ethertype-reg arp-label)

Generate instructions to check if packet is ARP. Jumps to arp-label if ARP, falls through otherwise.

ethertype-reg: Register containing ethertype (network order) arp-label: Label offset to jump to if ARP

is-ipv4 clj

(is-ipv4 ethertype-reg ipv4-label)

Generate instructions to check if packet is IPv4. Jumps to ipv4-label if IPv4, falls through otherwise. Uses network byte order comparison (no conversion needed).

ethertype-reg: Register containing ethertype (network order) ipv4-label: Label offset to jump to if IPv4

is-ipv6 clj

(is-ipv6 ethertype-reg ipv6-label)

Generate instructions to check if packet is IPv6. Jumps to ipv6-label if IPv6, falls through otherwise.

ethertype-reg: Register containing ethertype (network order) ipv6-label: Label offset to jump to if IPv6

is-not-ipv4 clj

(is-not-ipv4 ethertype-reg not-ipv4-label)

Generate instructions to check if packet is NOT IPv4. Jumps to not-ipv4-label if not IPv4, falls through if IPv4.

ethertype-reg: Register containing ethertype (network order) not-ipv4-label: Label offset to jump to if not IPv4

load-dst-mac clj

(load-dst-mac dst-reg-hi dst-reg-lo data-reg)

Load destination MAC address (6 bytes) into two registers. First 4 bytes into dst-reg-hi, last 2 bytes into dst-reg-lo.

dst-reg-hi: Register for first 4 bytes dst-reg-lo: Register for last 2 bytes data-reg: Register pointing to Ethernet header

load-ethertype clj

(load-ethertype dst-reg data-reg)

Load ethertype into dst-reg (network byte order). For comparison, use the network-order constants. Assumes bounds already checked for ETH_HLEN bytes.

dst-reg: Destination register for ethertype data-reg: Register pointing to packet data start

load-ethertype-host clj

(load-ethertype-host dst-reg data-reg)

Load ethertype into dst-reg and convert to host byte order. Assumes bounds already checked for ETH_HLEN bytes.

dst-reg: Destination register for ethertype data-reg: Register pointing to packet data start

load-src-mac clj

(load-src-mac src-reg-hi src-reg-lo data-reg)

Load source MAC address (6 bytes) into two registers.

src-reg-hi: Register for first 4 bytes src-reg-lo: Register for last 2 bytes data-reg: Register pointing to Ethernet header

parse-ethernet clj

(parse-ethernet data-reg data-end-reg ethertype-reg fail-label scratch-reg)

Parse Ethernet header and extract ethertype. Returns instructions that:

1. Check bounds for Ethernet header
2. Load ethertype into dst-reg

data-reg: Register containing packet data pointer data-end-reg: Register containing data_end pointer ethertype-reg: Register to store ethertype fail-label: Label to jump to if bounds check fails scratch-reg: Scratch register for bounds check

store-dst-mac clj

(store-dst-mac data-reg mac-hi mac-lo)

Store destination MAC address from two registers.

data-reg: Register pointing to Ethernet header mac-hi: Register containing first 4 bytes mac-lo: Register containing last 2 bytes

store-src-mac clj

(store-src-mac data-reg mac-hi mac-lo)

Store source MAC address from two registers.

data-reg: Register pointing to Ethernet header mac-hi: Register containing first 4 bytes mac-lo: Register containing last 2 bytes

swap-macs clj

(swap-macs data-reg [hi1 lo1 hi2 lo2])

Swap source and destination MAC addresses. Uses 6 scratch registers or stack.

data-reg: Register pointing to Ethernet header scratch-regs: Vector of 4 scratch registers [hi1 lo1 hi2 lo2]