ndn-dpdk/container/strategycode

This package manages the BPF programs of NDN-DPDK's forwarding strategies. Every loaded strategy is identified by a numeric ID and has a (non-unique) short name for presentation purposes.

Strategy Loader

This package loads eBPF programs from an ELF object using two libraries: the DPDK BPF library and the uBPF library. DPDK contains a BPF validator that disallows loops, which is necessary for a forwarding strategy. uBPF has a limited ELF parser that is unable to handle ELF objects compiled by clang-4.0 and later.

To make these two libraries work together, load.c monkey-patches the rte_bpf_load function. When loading a strategy ELF object:

1. The Load function writes the ELF object to a temporary file.
2. DPDK's rte_bpf_elf_load reads the file and processes the relocations.
3. The rte_bpf_load monkey patch receives eBPF instructions and passes them to uBPF.
4. A struct ubpf_vm* pointer is stored into the bpf->prm.xsym variable.