bird/lib/flowspec.c
Ondrej Zajicek (work) 78e4a123bb BGP: Handle flowspec rules without dst part
The RFC 5575 does not explicitly reject flowspec rules without dst part,
it just requires dst part in validation procedure for feasibility, which
we do not implement anyway. Thus flow without dst prefix is syntactically
valid, but unfeasible (if feasibilty testing is done).

Thanks to Alex D. for the bugreport.
2020-03-03 17:45:16 +01:00

1211 lines
30 KiB
C

/*
* BIRD Library -- Flow specification (RFC 5575)
*
* (c) 2016 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Flow specification (flowspec)
*
* Flowspec are rules (RFC 5575) for firewalls disseminated using BGP protocol.
* The |flowspec.c| is a library for handling flowspec binary streams and
* flowspec data structures. You will find there functions for validation
* incoming flowspec binary streams, iterators for jumping over components,
* functions for handling a length and functions for formatting flowspec data
* structure into user-friendly text representation.
*
* In this library, you will find also flowspec builder. In |confbase.Y|, there
* are grammar's rules for parsing and building new flowspec data structure
* from BIRD's configuration files and from BIRD's command line interface.
* Finalize function will assemble final &net_addr_flow4 or &net_addr_flow6
* data structure.
*
* The data structures &net_addr_flow4 and &net_addr_flow6 are defined in
* |net.h| file. The attribute length is size of whole data structure plus
* binary stream representation of flowspec including a compressed encoded
* length of flowspec.
*
* Sometimes in code, it is used expression flowspec type, it should mean
* flowspec component type.
*/
#include "nest/bird.h"
#include "lib/flowspec.h"
#include "conf/conf.h"
static const char* flow4_type_str[] = {
[FLOW_TYPE_DST_PREFIX] = "dst",
[FLOW_TYPE_SRC_PREFIX] = "src",
[FLOW_TYPE_IP_PROTOCOL] = "proto",
[FLOW_TYPE_PORT] = "port",
[FLOW_TYPE_DST_PORT] = "dport",
[FLOW_TYPE_SRC_PORT] = "sport",
[FLOW_TYPE_ICMP_TYPE] = "icmp type",
[FLOW_TYPE_ICMP_CODE] = "icmp code",
[FLOW_TYPE_TCP_FLAGS] = "tcp flags",
[FLOW_TYPE_PACKET_LENGTH] = "length",
[FLOW_TYPE_DSCP] = "dscp",
[FLOW_TYPE_FRAGMENT] = "fragment"
};
static const char* flow6_type_str[] = {
[FLOW_TYPE_DST_PREFIX] = "dst",
[FLOW_TYPE_SRC_PREFIX] = "src",
[FLOW_TYPE_NEXT_HEADER] = "next header",
[FLOW_TYPE_PORT] = "port",
[FLOW_TYPE_DST_PORT] = "dport",
[FLOW_TYPE_SRC_PORT] = "sport",
[FLOW_TYPE_ICMP_TYPE] = "icmp type",
[FLOW_TYPE_ICMP_CODE] = "icmp code",
[FLOW_TYPE_TCP_FLAGS] = "tcp flags",
[FLOW_TYPE_PACKET_LENGTH] = "length",
[FLOW_TYPE_DSCP] = "dscp",
[FLOW_TYPE_FRAGMENT] = "fragment",
[FLOW_TYPE_LABEL] = "label"
};
/**
* flow_type_str - get stringified flowspec name of component
* @type: flowspec component type
* @ipv6: IPv4/IPv6 decide flag, use zero for IPv4 and one for IPv6
*
* This function returns flowspec name of component @type in string.
*/
const char *
flow_type_str(enum flow_type type, int ipv6)
{
return ipv6 ? flow6_type_str[type] : flow4_type_str[type];
}
/*
* Length
*/
/**
* flow_write_length - write compressed length value
* @data: destination buffer to write
* @len: the value of the length (0 to 0xfff) for writing
*
* This function writes appropriate as (1- or 2-bytes) the value of @len into
* buffer @data. The function returns number of written bytes, thus 1 or 2 bytes.
*/
uint
flow_write_length(byte *data, u16 len)
{
if (len >= 0xf0)
{
put_u16(data, len | 0xf000);
return 2;
}
*data = len;
return 1;
}
inline static uint
get_value_length(const byte *op)
{
return (1 << ((*op & 0x30) >> 4));
}
/*
* Flowspec iterators
*/
static inline u8 num_op(const byte *op) { return (*op & 0x07); }
static inline int isset_and(const byte *op) { return ((*op & 0x40) == 0x40); }
static inline int isset_end(const byte *op) { return ((*op & 0x80) == 0x80); }
static const byte *
flow_first_part(const byte *data)
{
if (!data || flow_read_length(data) == 0)
return NULL;
/* It is allowed to encode the value of length less then 240 into 2-bytes too */
if ((data[0] & 0xf0) == 0xf0)
return data + 2;
return data + 1;
}
/**
* flow4_first_part - get position of the first flowspec component
* @f: flowspec data structure &net_addr_flow4
*
* This function return a position to the beginning of the first flowspec
* component in IPv4 flowspec @f.
*/
inline const byte *
flow4_first_part(const net_addr_flow4 *f)
{
return f ? flow_first_part(f->data) : NULL;
}
/**
* flow6_first_part - get position of the first flowspec component
* @f: flowspec data structure &net_addr_flow6
*
* This function return a position to the beginning of the first flowspec
* component in IPv6 flowspec @f.
*/
inline const byte *
flow6_first_part(const net_addr_flow6 *f)
{
return f ? flow_first_part(f->data) : NULL;
}
static const byte *
flow_next_part(const byte *pos, const byte *end, int ipv6)
{
switch (*pos++)
{
case FLOW_TYPE_DST_PREFIX:
case FLOW_TYPE_SRC_PREFIX:
{
uint pxlen = *pos++;
uint bytes = BYTES(pxlen);
if (ipv6)
{
uint offset = *pos++ / 8;
pos += bytes - offset;
}
else
{
pos += bytes;
}
break;
}
case FLOW_TYPE_IP_PROTOCOL: /* == FLOW_TYPE_NEXT_HEADER */
case FLOW_TYPE_PORT:
case FLOW_TYPE_DST_PORT:
case FLOW_TYPE_SRC_PORT:
case FLOW_TYPE_ICMP_TYPE:
case FLOW_TYPE_ICMP_CODE:
case FLOW_TYPE_TCP_FLAGS:
case FLOW_TYPE_PACKET_LENGTH:
case FLOW_TYPE_DSCP:
case FLOW_TYPE_FRAGMENT:
case FLOW_TYPE_LABEL:
{
/* Is this the end of list operator-value pair? */
uint last = 0;
while (!last)
{
last = isset_end(pos);
/* Value length of operator */
uint len = get_value_length(pos);
pos += 1+len;
}
break;
}
default:
return NULL;
}
return (pos < end) ? pos : NULL;
}
/**
* flow4_next_part - an iterator over flowspec components in flowspec binary stream
* @pos: the beginning of a previous or the first component in flowspec binary
* stream
* @end: the last valid byte in scanned flowspec binary stream
*
* This function returns a position to the beginning of the next component
* (to a component type byte) in flowspec binary stream or %NULL for the end.
*/
inline const byte *
flow4_next_part(const byte *pos, const byte *end)
{
return flow_next_part(pos, end, 0);
}
/**
* flow6_next_part - an iterator over flowspec components in flowspec binary stream
* @pos: the beginning of a previous or the first component in flowspec binary
* stream
* @end: the last valid byte in scanned flowspec binary stream
*
* This function returns a position to the beginning of the next component
* (to a component type byte) in flowspec binary stream or %NULL for the end.
*/
inline const byte *
flow6_next_part(const byte *pos, const byte *end)
{
return flow_next_part(pos, end, 1);
}
static const byte *
flow_get_part(const byte *data, uint dlen, uint type, int ipv6)
{
const byte *part;
for (part = flow_first_part(data);
part && (part[0] <= type);
part = flow_next_part(part, data+dlen, ipv6))
if (part[0] == type)
return part;
return NULL;
}
const byte *
flow4_get_part(const net_addr_flow4 *f, uint type)
{
return flow_get_part(f->data, f->length - sizeof(net_addr_flow4), type, 0);
}
const byte *
flow6_get_part(const net_addr_flow6 *f, uint type)
{
return flow_get_part(f->data, f->length - sizeof(net_addr_flow6), type, 1);
}
/*
* Flowspec accessors
*/
static inline ip4_addr
flow_read_ip4(const byte *px, uint pxlen)
{
ip4_addr ip = IP4_NONE;
memcpy(&ip, px, BYTES(pxlen));
return ip4_ntoh(ip);
}
ip4_addr
flow_read_ip4_part(const byte *part)
{
return flow_read_ip4(part + 2, part[1]);
}
static inline ip6_addr
flow_read_ip6(const byte *px, uint pxlen, uint pxoffset)
{
uint floor_offset = BYTES(pxoffset - (pxoffset % 8));
uint ceil_len = BYTES(pxlen);
ip6_addr ip = IP6_NONE;
memcpy(((byte *) &ip) + floor_offset, px, ceil_len - floor_offset);
return ip6_ntoh(ip);
}
ip6_addr
flow_read_ip6_part(const byte *part)
{
return flow_read_ip6(part + 3, part[1], part[2]);
}
/*
* Flowspec validation
*/
static const char* flow_validated_state_str_[] = {
[FLOW_ST_UNKNOWN_COMPONENT] = "Unknown component",
[FLOW_ST_VALID] = "Valid",
[FLOW_ST_NOT_COMPLETE] = "Not complete",
[FLOW_ST_EXCEED_MAX_PREFIX_LENGTH] = "Exceed maximal prefix length",
[FLOW_ST_EXCEED_MAX_PREFIX_OFFSET] = "Exceed maximal prefix offset",
[FLOW_ST_EXCEED_MAX_VALUE_LENGTH] = "Exceed maximal value length",
[FLOW_ST_BAD_TYPE_ORDER] = "Bad component order",
[FLOW_ST_AND_BIT_SHOULD_BE_UNSET] = "The AND-bit should be unset",
[FLOW_ST_ZERO_BIT_SHOULD_BE_UNSED] = "The Zero-bit should be unset",
[FLOW_ST_DEST_PREFIX_REQUIRED] = "Destination prefix is missing",
[FLOW_ST_INVALID_TCP_FLAGS] = "TCP flags exceeding 0xfff",
[FLOW_ST_CANNOT_USE_DONT_FRAGMENT] = "Cannot use Don't fragment flag in IPv6 flow"
};
/**
* flow_validated_state_str - return a textual description of validation process
* @code: validation result
*
* This function return well described validation state in string.
*/
const char *
flow_validated_state_str(enum flow_validated_state code)
{
return flow_validated_state_str_[code];
}
static const u8 flow4_max_value_length[] = {
[FLOW_TYPE_DST_PREFIX] = 0,
[FLOW_TYPE_SRC_PREFIX] = 0,
[FLOW_TYPE_IP_PROTOCOL] = 1,
[FLOW_TYPE_PORT] = 2,
[FLOW_TYPE_DST_PORT] = 2,
[FLOW_TYPE_SRC_PORT] = 2,
[FLOW_TYPE_ICMP_TYPE] = 1,
[FLOW_TYPE_ICMP_CODE] = 1,
[FLOW_TYPE_TCP_FLAGS] = 2,
[FLOW_TYPE_PACKET_LENGTH] = 2,
[FLOW_TYPE_DSCP] = 1,
[FLOW_TYPE_FRAGMENT] = 1 /* XXX */
};
static const u8 flow6_max_value_length[] = {
[FLOW_TYPE_DST_PREFIX] = 0,
[FLOW_TYPE_SRC_PREFIX] = 0,
[FLOW_TYPE_NEXT_HEADER] = 1,
[FLOW_TYPE_PORT] = 2,
[FLOW_TYPE_DST_PORT] = 2,
[FLOW_TYPE_SRC_PORT] = 2,
[FLOW_TYPE_ICMP_TYPE] = 1,
[FLOW_TYPE_ICMP_CODE] = 1,
[FLOW_TYPE_TCP_FLAGS] = 2,
[FLOW_TYPE_PACKET_LENGTH] = 2,
[FLOW_TYPE_DSCP] = 1,
[FLOW_TYPE_FRAGMENT] = 1, /* XXX */
[FLOW_TYPE_LABEL] = 4
};
static u8
flow_max_value_length(enum flow_type type, int ipv6)
{
return ipv6 ? flow6_max_value_length[type] : flow4_max_value_length[type];
}
/**
* flow_check_cf_bmk_values - check value/bitmask part of flowspec component
* @fb: flow builder instance
* @neg: negation operand
* @val: value from value/mask pair
* @mask: bitmap mask from value/mask pair
*
* This function checks value/bitmask pair. If some problem will appear, the
* function calls cf_error() function with a textual description of reason
* to failing of validation.
*/
void
flow_check_cf_bmk_values(struct flow_builder *fb, u8 neg, u32 val, u32 mask)
{
flow_check_cf_value_length(fb, val);
flow_check_cf_value_length(fb, mask);
if (neg && !(val == 0 || val == mask))
cf_error("For negation, value must be zero or bitmask");
if ((fb->this_type == FLOW_TYPE_TCP_FLAGS) && (mask & 0xf000))
cf_error("Invalid mask 0x%x, must not exceed 0xfff", mask);
if ((fb->this_type == FLOW_TYPE_FRAGMENT) && fb->ipv6 && (mask & 0x01))
cf_error("Invalid mask 0x%x, bit 0 must be 0", mask);
if (val & ~mask)
cf_error("Value 0x%x outside bitmask 0x%x", val, mask);
}
/**
* flow_check_cf_value_length - check value by flowspec component type
* @fb: flow builder instance
* @val: value
*
* This function checks if the value is in range of component's type support.
* If some problem will appear, the function calls cf_error() function with
* a textual description of reason to failing of validation.
*/
void
flow_check_cf_value_length(struct flow_builder *fb, u32 val)
{
enum flow_type t = fb->this_type;
u8 max = flow_max_value_length(t, fb->ipv6);
if (t == FLOW_TYPE_DSCP && val > 0x3f)
cf_error("%s value %u out of range (0-63)", flow_type_str(t, fb->ipv6), val);
if (max == 1 && (val > 0xff))
cf_error("%s value %u out of range (0-255)", flow_type_str(t, fb->ipv6), val);
if (max == 2 && (val > 0xffff))
cf_error("%s value %u out of range (0-65535)", flow_type_str(t, fb->ipv6), val);
}
static enum flow_validated_state
flow_validate(const byte *nlri, uint len, int ipv6)
{
enum flow_type type = 0;
const byte *pos = nlri;
const byte *end = nlri + len;
while (pos < end)
{
/* Check increasing type ordering */
if (*pos <= type)
return FLOW_ST_BAD_TYPE_ORDER;
type = *pos++;
switch (type)
{
case FLOW_TYPE_DST_PREFIX:
case FLOW_TYPE_SRC_PREFIX:
{
uint pxlen = *pos++;
if (pxlen > (ipv6 ? IP6_MAX_PREFIX_LENGTH : IP4_MAX_PREFIX_LENGTH))
return FLOW_ST_EXCEED_MAX_PREFIX_LENGTH;
uint bytes = BYTES(pxlen);
if (ipv6)
{
uint pxoffset = *pos++;
if (pxoffset > IP6_MAX_PREFIX_LENGTH || pxoffset > pxlen)
return FLOW_ST_EXCEED_MAX_PREFIX_OFFSET;
bytes -= pxoffset / 8;
}
pos += bytes;
break;
}
case FLOW_TYPE_LABEL:
if (!ipv6)
return FLOW_ST_UNKNOWN_COMPONENT;
/* fall through */
case FLOW_TYPE_IP_PROTOCOL: /* == FLOW_TYPE_NEXT_HEADER */
case FLOW_TYPE_PORT:
case FLOW_TYPE_DST_PORT:
case FLOW_TYPE_SRC_PORT:
case FLOW_TYPE_ICMP_TYPE:
case FLOW_TYPE_ICMP_CODE:
case FLOW_TYPE_TCP_FLAGS:
case FLOW_TYPE_PACKET_LENGTH:
case FLOW_TYPE_DSCP:
case FLOW_TYPE_FRAGMENT:
{
uint last = 0;
uint first = 1;
while (!last)
{
/*
* 0 1 2 3 4 5 6 7
* +---+---+---+---+---+---+---+---+
* | e | a | len | 0 |lt |gt |eq |
* +---+---+---+---+---+---+---+---+
*
* Numeric operator
*/
last = isset_end(pos);
/* The AND bit should in the first operator byte of a sequence */
if (first && isset_and(pos))
return FLOW_ST_AND_BIT_SHOULD_BE_UNSET;
/* This bit should be zero */
if (*pos & 0x08)
return FLOW_ST_ZERO_BIT_SHOULD_BE_UNSED;
if (type == FLOW_TYPE_TCP_FLAGS || type == FLOW_TYPE_FRAGMENT)
{
/*
* 0 1 2 3 4 5 6 7
* +---+---+---+---+---+---+---+---+
* | e | a | len | 0 | 0 |not| m |
* +---+---+---+---+---+---+---+---+
*
* Bitmask operand
*/
if (*pos & 0x04)
return FLOW_ST_ZERO_BIT_SHOULD_BE_UNSED;
}
/* Value length of operator */
uint len = get_value_length(pos);
if (len > flow_max_value_length(type, ipv6))
return FLOW_ST_EXCEED_MAX_VALUE_LENGTH;
/* TCP Flags component must not check highest nibble (just 12 valid bits) */
if ((type == FLOW_TYPE_TCP_FLAGS) && (len == 2) && (pos[1] & 0xf0))
return FLOW_ST_INVALID_TCP_FLAGS;
/* Bit-7 must be 0 [draft-ietf-idr-flow-spec-v6] */
if ((type == FLOW_TYPE_FRAGMENT) && ipv6 && (pos[1] & 0x01))
return FLOW_ST_CANNOT_USE_DONT_FRAGMENT;
/* XXX: Could be a fragment component encoded in 2-bytes? */
pos += 1+len;
if (pos > end && !last)
return FLOW_ST_NOT_COMPLETE;
if (pos > (end+1))
return FLOW_ST_NOT_COMPLETE;
first = 0;
}
break;
}
default:
return FLOW_ST_UNKNOWN_COMPONENT;
}
}
if (pos != end)
return FLOW_ST_NOT_COMPLETE;
return FLOW_ST_VALID;
}
/**
* flow4_validate - check untrustworthy IPv4 flowspec data stream
* @nlri: flowspec data stream without compressed encoded length value
* @len: length of @nlri
*
* This function checks meaningfulness of binary flowspec. It should return
* %FLOW_ST_VALID or %FLOW_ST_UNKNOWN_COMPONENT. If some problem appears, it
* returns some other %FLOW_ST_xxx state.
*/
inline enum flow_validated_state
flow4_validate(const byte *nlri, uint len)
{
return flow_validate(nlri, len, 0);
}
/**
* flow6_validate - check untrustworthy IPv6 flowspec data stream
* @nlri: flowspec binary stream without encoded length value
* @len: length of @nlri
*
* This function checks meaningfulness of binary flowspec. It should return
* %FLOW_ST_VALID or %FLOW_ST_UNKNOWN_COMPONENT. If some problem appears, it
* returns some other %FLOW_ST_xxx state.
*/
inline enum flow_validated_state
flow6_validate(const byte *nlri, uint len)
{
return flow_validate(nlri, len, 1);
}
/**
* flow4_validate_cf - validate flowspec data structure &net_addr_flow4 in parsing time
* @f: flowspec data structure &net_addr_flow4
*
* Check if @f is valid flowspec data structure. Can call cf_error() function
* with a textual description of reason to failing of validation.
*/
void
flow4_validate_cf(net_addr_flow4 *f)
{
enum flow_validated_state r = flow4_validate(flow4_first_part(f), flow_read_length(f->data));
if (r != FLOW_ST_VALID)
cf_error("Invalid flow route: %s", flow_validated_state_str(r));
}
/**
* flow6_validate_cf - validate flowspec data structure &net_addr_flow6 in parsing time
* @f: flowspec data structure &net_addr_flow6
*
* Check if @f is valid flowspec data structure. Can call cf_error() function
* with a textual description of reason to failing of validation.
*/
void
flow6_validate_cf(net_addr_flow6 *f)
{
enum flow_validated_state r = flow6_validate(flow6_first_part(f), flow_read_length(f->data));
if (r != FLOW_ST_VALID)
cf_error("Invalid flow route: %s", flow_validated_state_str(r));
}
/*
* Flowspec Builder
*/
/**
* flow_builder_init - constructor for flowspec builder instance
* @pool: memory pool
*
* This function prepares flowspec builder instance using memory pool @pool.
*/
struct flow_builder *
flow_builder_init(pool *pool)
{
struct flow_builder *fb = mb_allocz(pool, sizeof(struct flow_builder));
BUFFER_INIT(fb->data, pool, 4);
return fb;
}
static int
is_stackable_type(enum flow_type type)
{
switch (type)
{
case FLOW_TYPE_IP_PROTOCOL:
case FLOW_TYPE_PORT:
case FLOW_TYPE_DST_PORT:
case FLOW_TYPE_SRC_PORT:
case FLOW_TYPE_ICMP_TYPE:
case FLOW_TYPE_ICMP_CODE:
case FLOW_TYPE_TCP_FLAGS:
case FLOW_TYPE_PACKET_LENGTH:
case FLOW_TYPE_DSCP:
case FLOW_TYPE_FRAGMENT:
case FLOW_TYPE_LABEL:
return 1;
default:
/* The unknown components are not stack-able in default */
return 0;
}
}
static int
builder_add_prepare(struct flow_builder *fb)
{
if (fb->parts[fb->this_type].length)
{
if (fb->last_type != fb->this_type)
return 0;
if (!is_stackable_type(fb->this_type))
return 0;
}
else
{
fb->parts[fb->this_type].offset = fb->data.used;
}
return 1;
}
static void
builder_add_finish(struct flow_builder *fb)
{
fb->parts[fb->this_type].length = fb->data.used - fb->parts[fb->this_type].offset;
flow_builder_set_type(fb, fb->this_type);
}
static void
push_pfx_to_buffer(struct flow_builder *fb, u8 pxlen_bytes, byte *ip)
{
for (int i = 0; i < pxlen_bytes; i++)
BUFFER_PUSH(fb->data) = *ip++;
}
/**
* flow_builder4_add_pfx - add IPv4 prefix
* @fb: flowspec builder instance
* @n4: net address of type IPv4
*
* This function add IPv4 prefix into flowspec builder instance.
*/
int
flow_builder4_add_pfx(struct flow_builder *fb, const net_addr_ip4 *n4)
{
if (!builder_add_prepare(fb))
return 0;
ip4_addr ip4 = ip4_hton(n4->prefix);
BUFFER_PUSH(fb->data) = fb->this_type;
BUFFER_PUSH(fb->data) = n4->pxlen;
push_pfx_to_buffer(fb, BYTES(n4->pxlen), (byte *) &ip4);
builder_add_finish(fb);
return 1;
}
/**
* flow_builder6_add_pfx - add IPv6 prefix
* @fb: flowspec builder instance
* @n6: net address of type IPv4
* @pxoffset: prefix offset for @n6
*
* This function add IPv4 prefix into flowspec builder instance. This function
* should return 1 for successful adding, otherwise returns %0.
*/
int
flow_builder6_add_pfx(struct flow_builder *fb, const net_addr_ip6 *n6, u32 pxoffset)
{
if (!builder_add_prepare(fb))
return 0;
ip6_addr ip6 = ip6_hton(n6->prefix);
BUFFER_PUSH(fb->data) = fb->this_type;
BUFFER_PUSH(fb->data) = n6->pxlen;
BUFFER_PUSH(fb->data) = pxoffset;
push_pfx_to_buffer(fb, BYTES(n6->pxlen) - (pxoffset / 8), ((byte *) &ip6) + (pxoffset / 8));
builder_add_finish(fb);
return 1;
}
/**
* flow_builder_add_op_val - add operator/value pair
* @fb: flowspec builder instance
* @op: operator
* @value: value
*
* This function add operator/value pair as a part of a flowspec component. It
* is required to set appropriate flowspec component type using function
* flow_builder_set_type(). This function should return 1 for successful
* adding, otherwise returns 0.
*/
int
flow_builder_add_op_val(struct flow_builder *fb, byte op, u32 value)
{
if (!builder_add_prepare(fb))
return 0;
if (fb->this_type == fb->last_type)
{
/* Remove the end-bit from last operand-value pair of the component */
fb->data.data[fb->last_op_offset] &= 0x7f;
}
else
{
BUFFER_PUSH(fb->data) = fb->this_type;
}
fb->last_op_offset = fb->data.used;
/* Set the end-bit for operand-value pair of the component */
op |= 0x80;
if (value & 0xff00)
{
BUFFER_PUSH(fb->data) = op | 0x10;
put_u16(BUFFER_INC(fb->data, 2), value);
}
else
{
BUFFER_PUSH(fb->data) = op;
BUFFER_PUSH(fb->data) = (u8) value;
}
builder_add_finish(fb);
return 1;
}
/**
* flow_builder_add_val_mask - add value/bitmask pair
* @fb: flowspec builder instance
* @op: operator
* @value: value
* @mask: bitmask
*
* It is required to set appropriate flowspec component type using function
* flow_builder_set_type(). This function should return 1 for successful adding,
* otherwise returns 0.
*/
int
flow_builder_add_val_mask(struct flow_builder *fb, byte op, u32 value, u32 mask)
{
u32 a = value & mask;
u32 b = ~value & mask;
if (a)
{
flow_builder_add_op_val(fb, op ^ 0x01, a);
op |= FLOW_OP_AND;
}
if (b)
flow_builder_add_op_val(fb, op ^ 0x02, b);
return 1;
}
/**
* flow_builder_set_type - set type of next flowspec component
* @fb: flowspec builder instance
* @type: flowspec component type
*
* This function sets type of next flowspec component. It is necessary to call
* this function before each changing of adding flowspec component.
*/
void
flow_builder_set_type(struct flow_builder *fb, enum flow_type type)
{
fb->last_type = fb->this_type;
fb->this_type = type;
}
static void
builder_write_parts(struct flow_builder *fb, byte *buf)
{
for (int i = 1; i < FLOW_TYPE_MAX; i++)
{
if (fb->parts[i].length)
{
memcpy(buf, fb->data.data + fb->parts[i].offset, fb->parts[i].length);
buf += fb->parts[i].length;
}
}
}
/**
* flow_builder4_finalize - assemble final flowspec data structure &net_addr_flow4
* @fb: flowspec builder instance
* @lpool: linear memory pool
*
* This function returns final flowspec data structure &net_addr_flow4 allocated
* onto @lpool linear memory pool.
*/
net_addr_flow4 *
flow_builder4_finalize(struct flow_builder *fb, linpool *lpool)
{
uint data_len = fb->data.used + (fb->data.used < 0xf0 ? 1 : 2);
net_addr_flow4 *f = lp_alloc(lpool, sizeof(struct net_addr_flow4) + data_len);
ip4_addr prefix = IP4_NONE;
uint pxlen = 0;
if (fb->parts[FLOW_TYPE_DST_PREFIX].length)
{
byte *part = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset;
prefix = flow_read_ip4_part(part);
pxlen = flow_read_pxlen(part);
}
*f = NET_ADDR_FLOW4(prefix, pxlen, data_len);
builder_write_parts(fb, f->data + flow_write_length(f->data, fb->data.used));
return f;
}
/**
* flow_builder6_finalize - assemble final flowspec data structure &net_addr_flow6
* @fb: flowspec builder instance
* @lpool: linear memory pool for allocation of
*
* This function returns final flowspec data structure &net_addr_flow6 allocated
* onto @lpool linear memory pool.
*/
net_addr_flow6 *
flow_builder6_finalize(struct flow_builder *fb, linpool *lpool)
{
uint data_len = fb->data.used + (fb->data.used < 0xf0 ? 1 : 2);
net_addr_flow6 *n = lp_alloc(lpool, sizeof(net_addr_flow6) + data_len);
ip6_addr prefix = IP6_NONE;
uint pxlen = 0;
if (fb->parts[FLOW_TYPE_DST_PREFIX].length)
{
byte *part = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset;
prefix = flow_read_ip6_part(part);
pxlen = flow_read_pxlen(part);
}
*n = NET_ADDR_FLOW6(prefix, pxlen, data_len);
builder_write_parts(fb, n->data + flow_write_length(n->data, fb->data.used));
return n;
}
/**
* flow_builder_clear - flush flowspec builder instance for another flowspec creation
* @fb: flowspec builder instance
*
* This function flushes all data from builder but it maintains pre-allocated
* buffer space.
*/
void
flow_builder_clear(struct flow_builder *fb)
{
BUFFER(byte) data;
BUFFER_FLUSH(fb->data);
BUFFER_SHALLOW_COPY(data, fb->data);
memset(fb, 0, sizeof(struct flow_builder));
BUFFER_SHALLOW_COPY(fb->data, data);
}
/*
* Net Formatting
*/
/* Flowspec operators for [op, value]+ pairs */
static const char *
num_op_str(const byte *op)
{
switch (*op & 0x07)
{
case FLOW_OP_TRUE: return "true";
case FLOW_OP_EQ: return "=";
case FLOW_OP_GT: return ">";
case FLOW_OP_GEQ: return ">=";
case FLOW_OP_LT: return "<";
case FLOW_OP_LEQ: return "<=";
case FLOW_OP_NEQ: return "!=";
case FLOW_OP_FALSE: return "false";
}
return NULL;
}
static uint
get_value(const byte *val, u8 len)
{
switch (len)
{
case 1: return *val;
case 2: return get_u16(val);
case 4: return get_u32(val);
// No component may have length 8
// case 8: return get_u64(val);
}
return 0;
}
static const char *
fragment_val_str(u8 val)
{
switch (val)
{
case 1: return "dont_fragment";
case 2: return "is_fragment";
case 4: return "first_fragment";
case 8: return "last_fragment";
}
return "???";
}
static void
net_format_flow_ip(buffer *b, const byte *part, int ipv6)
{
uint pxlen = part[1];
if (ipv6)
{
uint pxoffset = part[2];
if (pxoffset)
buffer_print(b, "%I6/%u offset %u; ", flow_read_ip6_part(part), pxlen, pxoffset);
else
buffer_print(b, "%I6/%u; ", flow_read_ip6_part(part), pxlen);
}
else
{
buffer_print(b, "%I4/%u; ", flow_read_ip4_part(part), pxlen);
}
}
static void
net_format_flow_num(buffer *b, const byte *part)
{
const byte *last_op = NULL;
const byte *op = part+1;
uint val;
uint len;
uint first = 1;
while (1)
{
if (!first)
{
/* XXX: I don't like this so complicated if-tree */
if (!isset_and(op) &&
((num_op( op) == FLOW_OP_EQ) || (num_op( op) == FLOW_OP_GEQ)) &&
((num_op(last_op) == FLOW_OP_EQ) || (num_op(last_op) == FLOW_OP_LEQ)))
{
b->pos--; /* Remove last char (it is a space) */
buffer_puts(b, ",");
}
else
{
buffer_puts(b, isset_and(op) ? "&& " : "|| ");
}
}
first = 0;
len = get_value_length(op);
val = get_value(op+1, len);
if (!isset_end(op) && !isset_and(op) && isset_and(op+1+len) &&
(num_op(op) == FLOW_OP_GEQ) && (num_op(op+1+len) == FLOW_OP_LEQ))
{
/* Display interval */
buffer_print(b, "%u..", val);
op += 1 + len;
len = get_value_length(op);
val = get_value(op+1, len);
buffer_print(b, "%u", val);
}
else if (num_op(op) == FLOW_OP_EQ)
{
buffer_print(b, "%u", val);
}
else
{
buffer_print(b, "%s %u", num_op_str(op), val);
}
if (isset_end(op))
{
buffer_puts(b, "; ");
break;
}
else
{
buffer_puts(b, " ");
}
last_op = op;
op += 1 + len;
}
}
static void
net_format_flow_bitmask(buffer *b, const byte *part)
{
const byte *op = part+1;
uint val;
uint len;
uint first = 1;
while (1)
{
if (!first)
{
if (isset_and(op))
{
b->pos--; /* Remove last char (it is a space) */
buffer_puts(b, ",");
}
else
{
buffer_puts(b, "|| ");
}
}
first = 0;
len = get_value_length(op);
val = get_value(op+1, len);
/*
* Not Match Show
* ------------------
* 0 0 !0/B
* 0 1 B/B
* 1 0 0/B
* 1 1 !B/B
*/
if ((*op & 0x3) == 0x3 || (*op & 0x3) == 0)
buffer_puts(b, "!");
if (*part == FLOW_TYPE_FRAGMENT && (val == 1 || val == 2 || val == 4 || val == 8))
buffer_print(b, "%s%s", ((*op & 0x1) ? "" : "!"), fragment_val_str(val));
else
buffer_print(b, "0x%x/0x%x", ((*op & 0x1) ? val : 0), val);
if (isset_end(op))
{
buffer_puts(b, "; ");
break;
}
else
{
buffer_puts(b, " ");
}
op += 1 + len;
}
}
static uint
net_format_flow(char *buf, uint blen, const byte *data, uint dlen, int ipv6)
{
buffer b = {
.start = buf,
.pos = buf,
.end = buf + blen,
};
const byte *part = flow_first_part(data);
*buf = 0;
if (ipv6)
buffer_puts(&b, "flow6 { ");
else
buffer_puts(&b, "flow4 { ");
while (part)
{
buffer_print(&b, "%s ", flow_type_str(*part, ipv6));
switch (*part)
{
case FLOW_TYPE_DST_PREFIX:
case FLOW_TYPE_SRC_PREFIX:
net_format_flow_ip(&b, part, ipv6);
break;
case FLOW_TYPE_IP_PROTOCOL: /* == FLOW_TYPE_NEXT_HEADER */
case FLOW_TYPE_PORT:
case FLOW_TYPE_DST_PORT:
case FLOW_TYPE_SRC_PORT:
case FLOW_TYPE_ICMP_TYPE:
case FLOW_TYPE_ICMP_CODE:
case FLOW_TYPE_PACKET_LENGTH:
case FLOW_TYPE_DSCP:
net_format_flow_num(&b, part);
break;
case FLOW_TYPE_TCP_FLAGS:
case FLOW_TYPE_FRAGMENT:
case FLOW_TYPE_LABEL:
net_format_flow_bitmask(&b, part);
break;
}
part = flow_next_part(part, data+dlen, ipv6);
}
buffer_puts(&b, "}");
if (b.pos == b.end)
{
b.pos = b.start + MIN(blen - 6, strlen(b.start));
buffer_puts(&b, " ...}");
}
return b.pos - b.start;
}
/**
* flow4_net_format - stringify flowspec data structure &net_addr_flow4
* @buf: pre-allocated buffer for writing a stringify net address flowspec
* @blen: free allocated space in @buf
* @f: flowspec data structure &net_addr_flow4 for stringify
*
* This function writes stringified @f into @buf. The function returns number
* of written chars. If final string is too large, the string will ends the with
* ' ...}' sequence and zero-terminator.
*/
uint
flow4_net_format(char *buf, uint blen, const net_addr_flow4 *f)
{
return net_format_flow(buf, blen, f->data, f->length - sizeof(net_addr_flow4), 0);
}
/**
* flow6_net_format - stringify flowspec data structure &net_addr_flow6
* @buf: pre-allocated buffer for writing a stringify net address flowspec
* @blen: free allocated space in @buf
* @f: flowspec data structure &net_addr_flow4 for stringify
*
* This function writes stringified @f into @buf. The function returns number
* of written chars. If final string is too large, the string will ends the with
* ' ...}' sequence and zero-terminator.
*/
uint
flow6_net_format(char *buf, uint blen, const net_addr_flow6 *f)
{
return net_format_flow(buf, blen, f->data, f->length - sizeof(net_addr_flow6), 1);
}