1 /* SPDX-License-Identifier: BSD-2-Clause */
3 * dhcpcd: BPF arp and bootp filtering
4 * Copyright (c) 2006-2019 Roy Marples <roy@marples.name>
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8 * modification, are permitted provided that the following conditions
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32 #define BPF_READING (1U << 0)
33 #define BPF_EOF (1U << 1)
34 #define BPF_PARTIALCSUM (1U << 2)
35 #define BPF_BCAST (1U << 3)
38 * Even though we program the BPF filter should we trust it?
39 * On Linux at least there is a window between opening the socket,
40 * binding the interface and setting the filter where we receive data.
41 * This data is NOT checked OR flushed and IS returned when reading.
42 * We have no way of flushing it other than reading these packets!
43 * But we don't know if they passed the filter or not ..... so we need
44 * to validate each and every packet that comes through ourselves as well.
45 * Even if Linux does fix this sorry state, who is to say other kernels
46 * don't have bugs causing a similar effect?
48 * As such, let's strive to keep the filters just for pattern matching
49 * to avoid waking dhcpcd up.
51 * If you want to be notified of any packet failing the BPF filter,
52 * define BPF_DEBUG below.
58 extern const char *bpf_name;
59 size_t bpf_frame_header_len(const struct interface *);
60 int bpf_frame_bcast(const struct interface *, const char *frame);
61 int bpf_open(struct interface *, int (*)(struct interface *, int));
62 int bpf_close(struct interface *, int);
63 int bpf_attach(int, void *, unsigned int);
64 ssize_t bpf_send(const struct interface *, int, uint16_t, const void *, size_t);
65 ssize_t bpf_read(struct interface *, int, void *, size_t, unsigned int *);
66 int bpf_arp(struct interface *, int);
67 int bpf_bootp(struct interface *, int);