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/* bpf-engine.h
* ------------
* The BPF engine used for offline ("display") filters in wiretap.
* The code is taken from the Linux Socket Filter, and only slightly
* modified for use in wiretap.
*
* Gilbert Ramirez <gram@verdict.uthscsa.edu>
*/
/*
* Linux Socket Filter - Kernel level socket filtering
*
* Author:
* Jay Schulist <Jay.Schulist@spacs.k12.wi.us>
*
* Based on the design of:
* - The Berkeley Packet Filter
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
/*
* Linux Socket Filter Data Structures
*/
/*
* Current version of the filter code architecture.
*/
#define BPF_MAJOR_VERSION 1
#define BPF_MINOR_VERSION 1
/* each BPF instruction is a block of 8 bytes */
struct bpf_instruction {
guint16 code; /* Actual filter code */
guint8 jt; /* Jump true */
guint8 jf; /* Jump false */
guint32 k; /* Generic multiuse field */
};
struct bpf_code_unit {
int line_label;
struct bpf_instruction bpf;
};
int bpf_run_filter(unsigned char *data, int len, struct bpf_instruction *filter, int flen);
int bpf_chk_filter(struct bpf_instruction *filter, int flen);
/*
* Instruction classes
*/
#define BPF_CLASS(code) ((code) & 0x07)
#define BPF_LD 0x00
#define BPF_LDX 0x01
#define BPF_ST 0x02
#define BPF_STX 0x03
#define BPF_ALU 0x04
#define BPF_JMP 0x05
#define BPF_RET 0x06
#define BPF_MISC 0x07
/* ld/ldx fields */
#define BPF_SIZE(code) ((code) & 0x18)
#define BPF_W 0x00
#define BPF_H 0x08
#define BPF_B 0x10
#define BPF_MODE(code) ((code) & 0xe0)
#define BPF_IMM 0x00
#define BPF_ABS 0x20
#define BPF_IND 0x40
#define BPF_MEM 0x60
#define BPF_LEN 0x80
#define BPF_MSH 0xa0
/* alu/jmp fields */
#define BPF_OP(code) ((code) & 0xf0)
#define BPF_ADD 0x00
#define BPF_SUB 0x10
#define BPF_MUL 0x20
#define BPF_DIV 0x30
#define BPF_OR 0x40
#define BPF_AND 0x50
#define BPF_LSH 0x60
#define BPF_RSH 0x70
#define BPF_NEG 0x80
#define BPF_JA 0x00
#define BPF_JEQ 0x10
#define BPF_JGT 0x20
#define BPF_JGE 0x30
#define BPF_JSET 0x40
#define BPF_SRC(code) ((code) & 0x08)
#define BPF_K 0x00
#define BPF_X 0x08
/* ret - BPF_K and BPF_X also apply */
#define BPF_RVAL(code) ((code) & 0x18)
#define BPF_A 0x10
/* misc */
#define BPF_MISCOP(code) ((code) & 0xf8)
#define BPF_TAX 0x00
#define BPF_TXA 0x80
#define BPF_MAXINSNS 512
/*
* Macros for filter block array initializers.
*/
#define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
#define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
/*
* Number of scratch memory words for: BPF_ST and BPF_STX
*/
#define BPF_MEMWORDS 16
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