diff options
| -rw-r--r-- | gencode.c | 49 |
1 files changed, 30 insertions, 19 deletions
@@ -2902,6 +2902,7 @@ gen_linktype(proto) register int proto; { struct block *b0, *b1, *b2; + const char *description; /* are we checking MPLS-encapsulated packets? */ if (label_stack_depth > 0) { @@ -3418,26 +3419,36 @@ gen_linktype(proto) * either missing or behind TLVs. */ bpf_error("NFLOG link-layer type filtering not implemented"); - } - - /* - * All the types that have no encapsulation should either be - * handled as DLT_SLIP, DLT_SLIP_BSDOS, and DLT_RAW are, if - * all packets are IP packets, or should be handled in some - * special case, if none of them are (if some are and some - * aren't, the lack of encapsulation is a problem, as we'd - * have to find some other way of determining the packet type). - * - * Therefore, if "off_linktype" is -1, there's an error. - */ - if (off_linktype == (u_int)-1) - abort(); - /* - * Any type not handled above should always have an Ethernet - * type at an offset of "off_linktype". - */ - return gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto); + default: + /* + * Does this link-layer header type have a field + * indicating the type of the next protocol? If + * so, off_linktype will be the offset of that + * field in the packet; if not, it will be -1. + */ + if (off_linktype != (u_int)-1) { + /* + * Yes; assume it's an Ethernet type. (If + * it's not, it needs to be handled specially + * above.) + */ + return gen_cmp(OR_LINK, off_linktype, BPF_H, (bpf_int32)proto); + } else { + /* + * No; report an error. + */ + description = pcap_datalink_val_to_description(linktype); + if (description != NULL) { + bpf_error("%s link-layer type filtering not implemented", + description); + } else { + bpf_error("DLT %u link-layer type filtering not implemented", + linktype); + } + } + break; + } } /* |