// Generate and return the Filter associated with the Builder.
func (b *Builder) Build() *Filter {
prog := (*C.struct_bpf_program)(b.filter.Program())
flen := int(C.bpf_get_len(prog))
for i := 0; i < flen; i++ {
insn := C.bpf_get_insn(prog, C.int(i))
if lbl, ok := b.jumps_k[i]; ok {
addr := b.labels[lbl]
if addr != 0 {
insn.k = C.bpf_u_int32(addr - i - 1)
}
}
if lbl, ok := b.jumps_jt[i]; ok {
addr := b.labels[lbl]
if addr != 0 {
insn.jt = C.u_char(addr - i - 1)
}
}
if lbl, ok := b.jumps_jf[i]; ok {
addr := b.labels[lbl]
if addr != 0 {
insn.jf = C.u_char(addr - i - 1)
}
}
}
return b.filter
}
func (f *Filter) String() string {
var insns []string
prog := (*C.struct_bpf_program)(f.Program())
flen := C.bpf_get_len(prog)
for i := C.int(0); i < flen; i++ {
insn := C.bpf_get_insn(prog, i)
str := fmt.Sprintf(
"{ 0x%.2x, %3d, %3d, 0x%.8x },",
insn.code, insn.jt, insn.jf, insn.k,
)
insns = append(insns, str)
}
return strings.Join(insns, "\n")
}
// Return the number of instructions in the filter.
func (f *Filter) Len() int {
prog := (*C.struct_bpf_program)(f.Program())
flen := C.bpf_get_len(prog)
return int(flen)
}