ip_fw.h

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/*
 * Copyright (c) 1993 Daniel Boulet
 * Copyright (c) 1994 Ugen J.S.Antsilevich
 *
 * Redistribution and use in source forms, with and without modification,
 * are permitted provided that this entire comment appears intact.
 *
 * Redistribution in binary form may occur without any restrictions.
 * Obviously, it would be nice if you gave credit where credit is due
 * but requiring it would be too onerous.
 *
 * This software is provided ``AS IS'' without any warranties of any kind.
 */

#ifndef _IP_FW_H
#define _IP_FW_H

#include <sys/queue.h> /* LIST_ENTRY */
#include <net/if.h>
#include <netinet/in.h> /* struct in_addr */

/*
 * This union structure identifies an interface, either explicitly
 * by name or implicitly by IP address. The flags IP_FW_F_IIFNAME
 * and IP_FW_F_OIFNAME say how to interpret this structure. An
 * interface unit number of -1 matches any unit number, while an
 * IP address of 0.0.0.0 indicates matches any interface.
 *
 * The receive and transmit interfaces are only compared against the
 * the packet if the corresponding bit (IP_FW_F_IIFACE or IP_FW_F_OIFACE)
 * is set. Note some packets lack a receive or transmit interface
 * (in which case the missing "interface" never matches).
 */

union ip_fw_if {
    struct in_addr fu_via_ip;   /* Specified by IP address */
    struct {                    /* Specified by interface name */
#define FW_IFNLEN     IFNAMSIZ
            char  name[FW_IFNLEN];
            short unit;         /* -1 means match any unit */
    } fu_via_if;
};

/*
 * Format of an IP firewall descriptor
 *
 * fw_src, fw_dst, fw_smsk, fw_dmsk are always stored in network byte order.
 * fw_flg and fw_n*p are stored in host byte order (of course).
 * Port numbers are stored in HOST byte order.
 * Warning: setsockopt() will fail if sizeof(struct ip_fw) > MLEN (108)
 */

struct ip_fw {
    u_long fw_pcnt,fw_bcnt;             /* Packet and byte counters */
    struct in_addr fw_src, fw_dst;      /* Source and destination IP addr */
    struct in_addr fw_smsk, fw_dmsk;    /* Mask for src and dest IP addr */
    u_short fw_number;                  /* Rule number */
    u_short fw_flg;                     /* Flags word */
#define IP_FW_MAX_PORTS 10              /* A reasonable maximum */
    u_short fw_pts[IP_FW_MAX_PORTS];    /* Array of port numbers to match */
    u_char fw_ipopt,fw_ipnopt;          /* IP options set/unset */
    u_char fw_tcpf,fw_tcpnf;            /* TCP flags set/unset */
#define IP_FW_ICMPTYPES_DIM (32 / (sizeof(unsigned) * 8))
    unsigned fw_icmptypes[IP_FW_ICMPTYPES_DIM]; /* ICMP types bitmap */
    long timestamp;                     /* timestamp (tv_sec) of last match */
    union ip_fw_if fw_in_if, fw_out_if; /* Incoming and outgoing interfaces */
    union {
        u_short fu_divert_port;         /* Divert/tee port (options IPDIVERT) */
        u_short fu_skipto_rule;         /* SKIPTO command rule number */
        u_short fu_reject_code;         /* REJECT response code */
    } fw_un;
    u_char fw_prot;                     /* IP protocol */
    u_char fw_nports;                   /* N'of src ports and # of dst ports */
                                        /* in ports array (dst ports follow */
                                        /* src ports; max of 10 ports in all; */
                                        /* count of 0 means match all ports) */
};

#define IP_FW_GETNSRCP(rule)            ((rule)->fw_nports & 0x0f)
#define IP_FW_SETNSRCP(rule, n)         do {                            \
                                          (rule)->fw_nports &= ~0x0f;   \
                                          (rule)->fw_nports |= (n);     \
                                        } while (0)
#define IP_FW_GETNDSTP(rule)            ((rule)->fw_nports >> 4)
#define IP_FW_SETNDSTP(rule, n)         do {                            \
                                          (rule)->fw_nports &= ~0xf0;   \
                                          (rule)->fw_nports |= (n) << 4;\
                                        } while (0)

#define fw_divert_port  fw_un.fu_divert_port
#define fw_skipto_rule  fw_un.fu_skipto_rule
#define fw_reject_code  fw_un.fu_reject_code

struct ip_fw_chain {
        LIST_ENTRY(ip_fw_chain) chain;
        struct ip_fw    *rule;
};

/*
 * Values for "flags" field .
 */
#define IP_FW_F_IN      0x0001  /* Check inbound packets                */
#define IP_FW_F_OUT     0x0002  /* Check outbound packets               */
#define IP_FW_F_IIFACE  0x0004  /* Apply inbound interface test         */
#define IP_FW_F_OIFACE  0x0008  /* Apply outbound interface test        */

#define IP_FW_F_COMMAND 0x0070  /* Mask for type of chain entry:        */
#define IP_FW_F_DENY    0x0000  /* This is a deny rule                  */
#define IP_FW_F_REJECT  0x0010  /* Deny and send a response packet      */
#define IP_FW_F_ACCEPT  0x0020  /* This is an accept rule               */
#define IP_FW_F_COUNT   0x0030  /* This is a count rule                 */
#define IP_FW_F_DIVERT  0x0040  /* This is a divert rule                */
#define IP_FW_F_TEE     0x0050  /* This is a tee rule                   */
#define IP_FW_F_SKIPTO  0x0060  /* This is a skipto rule                */

#define IP_FW_F_PRN     0x0080  /* Print if this rule matches           */

#define IP_FW_F_SRNG    0x0100  /* The first two src ports are a min    *
                                 * and max range (stored in host byte   *
                                 * order).                              */

#define IP_FW_F_DRNG    0x0200  /* The first two dst ports are a min    *
                                 * and max range (stored in host byte   *
                                 * order).                              */

#define IP_FW_F_IIFNAME 0x0400  /* In interface by name/unit (not IP)   */
#define IP_FW_F_OIFNAME 0x0800  /* Out interface by name/unit (not IP)  */

#define IP_FW_F_INVSRC  0x1000  /* Invert sense of src check            */
#define IP_FW_F_INVDST  0x2000  /* Invert sense of dst check            */

#define IP_FW_F_FRAG    0x4000  /* Fragment                             */

#define IP_FW_F_ICMPBIT 0x8000  /* ICMP type bitmap is valid            */

#define IP_FW_F_MASK    0xFFFF  /* All possible flag bits mask          */

/*
 * For backwards compatibility with rules specifying "via iface" but
 * not restricted to only "in" or "out" packets, we define this combination
 * of bits to represent this configuration.
 */

#define IF_FW_F_VIAHACK (IP_FW_F_IN|IP_FW_F_OUT|IP_FW_F_IIFACE|IP_FW_F_OIFACE)

/*
 * Definitions for REJECT response codes.
 * Values less than 256 correspond to ICMP unreachable codes.
 */
#define IP_FW_REJECT_RST        0x0100          /* TCP packets: send RST */

/*
 * Definitions for IP option names.
 */
#define IP_FW_IPOPT_LSRR        0x01
#define IP_FW_IPOPT_SSRR        0x02
#define IP_FW_IPOPT_RR          0x04
#define IP_FW_IPOPT_TS          0x08

/*
 * Definitions for TCP flags.
 */
#define IP_FW_TCPF_FIN          TH_FIN
#define IP_FW_TCPF_SYN          TH_SYN
#define IP_FW_TCPF_RST          TH_RST
#define IP_FW_TCPF_PSH          TH_PUSH
#define IP_FW_TCPF_ACK          TH_ACK
#define IP_FW_TCPF_URG          TH_URG
#define IP_FW_TCPF_ESTAB        0x40

/*
 * Main firewall chains definitions and global var's definitions.
 */
#ifdef _KERNEL

/*
 * Function definitions.
 */
void ip_fw_init(void);

#endif /* _KERNEL */

#endif /* _IP_FW_H */