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ovs/lib/learn.c
Ben Pfaff 0c3d5fc89a ovs-ofctl: Add "packet-out" command. 
I don't expect this to be widely useful.  An upcoming commit will add a
use in unit tests.

Signed-off-by: Ben Pfaff <blp@nicira.com>
2012-02-09 13:23:37 -08:00

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/*
* Copyright (c) 2011, 2012 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "learn.h"
#include "byte-order.h"
#include "dynamic-string.h"
#include "meta-flow.h"
#include "nx-match.h"
#include "ofp-errors.h"
#include "ofp-util.h"
#include "ofpbuf.h"
#include "openflow/openflow.h"
#include "unaligned.h"
static ovs_be16
get_be16(const void **pp)
{
const ovs_be16 *p = *pp;
ovs_be16 value = *p;
*pp = p + 1;
return value;
}
static ovs_be32
get_be32(const void **pp)
{
const ovs_be32 *p = *pp;
ovs_be32 value = get_unaligned_be32(p);
*pp = p + 1;
return value;
}
static uint64_t
get_bits(int n_bits, const void **p)
{
int n_segs = DIV_ROUND_UP(n_bits, 16);
uint64_t value;
value = 0;
while (n_segs-- > 0) {
value = (value << 16) | ntohs(get_be16(p));
}
return value;
}
static void
get_subfield(int n_bits, const void **p, struct mf_subfield *sf)
{
sf->field = mf_from_nxm_header(ntohl(get_be32(p)));
sf->ofs = ntohs(get_be16(p));
sf->n_bits = n_bits;
}
static unsigned int
learn_min_len(uint16_t header)
{
int n_bits = header & NX_LEARN_N_BITS_MASK;
int src_type = header & NX_LEARN_SRC_MASK;
int dst_type = header & NX_LEARN_DST_MASK;
unsigned int min_len;
min_len = 0;
if (src_type == NX_LEARN_SRC_FIELD) {
min_len += sizeof(ovs_be32); /* src_field */
min_len += sizeof(ovs_be16); /* src_ofs */
} else {
min_len += DIV_ROUND_UP(n_bits, 16);
}
if (dst_type == NX_LEARN_DST_MATCH ||
dst_type == NX_LEARN_DST_LOAD) {
min_len += sizeof(ovs_be32); /* dst_field */
min_len += sizeof(ovs_be16); /* dst_ofs */
}
return min_len;
}
static enum ofperr
learn_check_header(uint16_t header, size_t len)
{
int src_type = header & NX_LEARN_SRC_MASK;
int dst_type = header & NX_LEARN_DST_MASK;
/* Check for valid src and dst type combination. */
if (dst_type == NX_LEARN_DST_MATCH ||
dst_type == NX_LEARN_DST_LOAD ||
(dst_type == NX_LEARN_DST_OUTPUT &&
src_type == NX_LEARN_SRC_FIELD)) {
/* OK. */
} else {
return OFPERR_OFPBAC_BAD_ARGUMENT;
}
/* Check that the arguments don't overrun the end of the action. */
if (len < learn_min_len(header)) {
return OFPERR_OFPBAC_BAD_LEN;
}
return 0;
}
/* Checks that 'learn' (which must be at least 'sizeof *learn' bytes long) is a
* valid action on 'flow'. */
enum ofperr
learn_check(const struct nx_action_learn *learn, const struct flow *flow)
{
struct cls_rule rule;
const void *p, *end;
cls_rule_init_catchall(&rule, 0);
if (learn->flags & ~htons(OFPFF_SEND_FLOW_REM)
|| !is_all_zeros(learn->pad, sizeof learn->pad)
|| learn->table_id == 0xff) {
return OFPERR_OFPBAC_BAD_ARGUMENT;
}
end = (char *) learn + ntohs(learn->len);
for (p = learn + 1; p != end; ) {
uint16_t header = ntohs(get_be16(&p));
int n_bits = header & NX_LEARN_N_BITS_MASK;
int src_type = header & NX_LEARN_SRC_MASK;
int dst_type = header & NX_LEARN_DST_MASK;
enum ofperr error;
uint64_t value;
if (!header) {
break;
}
error = learn_check_header(header, (char *) end - (char *) p);
if (error) {
return error;
}
/* Check the source. */
if (src_type == NX_LEARN_SRC_FIELD) {
struct mf_subfield src;
get_subfield(n_bits, &p, &src);
error = mf_check_src(&src, flow);
if (error) {
return error;
}
value = 0;
} else {
value = get_bits(n_bits, &p);
}
/* Check the destination. */
if (dst_type == NX_LEARN_DST_MATCH || dst_type == NX_LEARN_DST_LOAD) {
struct mf_subfield dst;
get_subfield(n_bits, &p, &dst);
error = (dst_type == NX_LEARN_DST_LOAD
? mf_check_dst(&dst, &rule.flow)
: mf_check_src(&dst, &rule.flow));
if (error) {
return error;
}
if (dst_type == NX_LEARN_DST_MATCH
&& src_type == NX_LEARN_SRC_IMMEDIATE) {
mf_set_subfield(&dst, value, &rule);
}
}
}
if (!is_all_zeros(p, (char *) end - (char *) p)) {
return OFPERR_OFPBAC_BAD_ARGUMENT;
}
return 0;
}
void
learn_execute(const struct nx_action_learn *learn, const struct flow *flow,
struct ofputil_flow_mod *fm)
{
const void *p, *end;
struct ofpbuf actions;
cls_rule_init_catchall(&fm->cr, ntohs(learn->priority));
fm->cookie = learn->cookie;
fm->table_id = learn->table_id;
fm->command = OFPFC_MODIFY_STRICT;
fm->idle_timeout = ntohs(learn->idle_timeout);
fm->hard_timeout = ntohs(learn->hard_timeout);
fm->buffer_id = UINT32_MAX;
fm->out_port = OFPP_NONE;
fm->flags = ntohs(learn->flags) & OFPFF_SEND_FLOW_REM;
fm->actions = NULL;
fm->n_actions = 0;
ofpbuf_init(&actions, 64);
for (p = learn + 1, end = (char *) learn + ntohs(learn->len); p != end; ) {
uint16_t header = ntohs(get_be16(&p));
int n_bits = header & NX_LEARN_N_BITS_MASK;
int src_type = header & NX_LEARN_SRC_MASK;
int dst_type = header & NX_LEARN_DST_MASK;
uint64_t value;
struct nx_action_reg_load *load;
struct mf_subfield dst;
if (!header) {
break;
}
if (src_type == NX_LEARN_SRC_FIELD) {
struct mf_subfield src;
get_subfield(n_bits, &p, &src);
value = mf_get_subfield(&src, flow);
} else {
value = get_bits(n_bits, &p);
}
switch (dst_type) {
case NX_LEARN_DST_MATCH:
get_subfield(n_bits, &p, &dst);
mf_set_subfield(&dst, value, &fm->cr);
break;
case NX_LEARN_DST_LOAD:
get_subfield(n_bits, &p, &dst);
load = ofputil_put_NXAST_REG_LOAD(&actions);
load->ofs_nbits = nxm_encode_ofs_nbits(dst.ofs, dst.n_bits);
load->dst = htonl(dst.field->nxm_header);
load->value = htonll(value);
break;
case NX_LEARN_DST_OUTPUT:
ofputil_put_OFPAT_OUTPUT(&actions)->port = htons(value);
break;
}
}
fm->actions = ofpbuf_steal_data(&actions);
fm->n_actions = actions.size / sizeof(struct ofp_action_header);
}
static void
put_be16(struct ofpbuf *b, ovs_be16 x)
{
ofpbuf_put(b, &x, sizeof x);
}
static void
put_be32(struct ofpbuf *b, ovs_be32 x)
{
ofpbuf_put(b, &x, sizeof x);
}
static void
put_u16(struct ofpbuf *b, uint16_t x)
{
put_be16(b, htons(x));
}
static void
put_u32(struct ofpbuf *b, uint32_t x)
{
put_be32(b, htonl(x));
}
struct learn_spec {
int n_bits;
int src_type;
struct mf_subfield src;
uint8_t src_imm[sizeof(union mf_value)];
int dst_type;
struct mf_subfield dst;
};
static void
learn_parse_spec(const char *orig, char *name, char *value,
struct learn_spec *spec)
{
memset(spec, 0, sizeof *spec);
if (mf_from_name(name)) {
const struct mf_field *dst = mf_from_name(name);
union mf_value imm;
char *error;
error = mf_parse_value(dst, value, &imm);
if (error) {
ovs_fatal(0, "%s", error);
}
spec->n_bits = dst->n_bits;
spec->src_type = NX_LEARN_SRC_IMMEDIATE;
memcpy(spec->src_imm, &imm, dst->n_bytes);
spec->dst_type = NX_LEARN_DST_MATCH;
spec->dst.field = dst;
spec->dst.ofs = 0;
spec->dst.n_bits = dst->n_bits;
} else if (strchr(name, '[')) {
/* Parse destination and check prerequisites. */
if (mf_parse_subfield(&spec->dst, name)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, name);
}
/* Parse source and check prerequisites. */
if (value[0] != '\0') {
if (mf_parse_subfield(&spec->src, value)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, value);
}
if (spec->src.n_bits != spec->dst.n_bits) {
ovs_fatal(0, "%s: bit widths of %s (%u) and %s (%u) differ",
orig, name, spec->src.n_bits, value,
spec->dst.n_bits);
}
} else {
spec->src = spec->dst;
}
spec->n_bits = spec->src.n_bits;
spec->src_type = NX_LEARN_SRC_FIELD;
spec->dst_type = NX_LEARN_DST_MATCH;
} else if (!strcmp(name, "load")) {
if (value[strcspn(value, "[-")] == '-') {
struct nx_action_reg_load load;
int nbits, imm_bytes;
uint64_t imm;
int i;
nxm_parse_reg_load(&load, value);
nbits = nxm_decode_n_bits(load.ofs_nbits);
imm_bytes = DIV_ROUND_UP(nbits, 8);
imm = ntohll(load.value);
spec->n_bits = nbits;
spec->src_type = NX_LEARN_SRC_IMMEDIATE;
for (i = 0; i < imm_bytes; i++) {
spec->src_imm[i] = imm >> ((imm_bytes - i - 1) * 8);
}
spec->dst_type = NX_LEARN_DST_LOAD;
nxm_decode(&spec->dst, load.dst, load.ofs_nbits);
} else {
struct nx_action_reg_move move;
nxm_parse_reg_move(&move, value);
spec->n_bits = ntohs(move.n_bits);
spec->src_type = NX_LEARN_SRC_FIELD;
nxm_decode_discrete(&spec->src,
move.src, move.src_ofs, move.n_bits);
spec->dst_type = NX_LEARN_DST_LOAD;
nxm_decode_discrete(&spec->dst,
move.dst, move.dst_ofs, move.n_bits);
}
} else if (!strcmp(name, "output")) {
if (mf_parse_subfield(&spec->src, value)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, name);
}
spec->n_bits = spec->src.n_bits;
spec->src_type = NX_LEARN_SRC_FIELD;
spec->dst_type = NX_LEARN_DST_OUTPUT;
} else {
ovs_fatal(0, "%s: unknown keyword %s", orig, name);
}
}
/* Parses 'arg' as a set of arguments to the "learn" action and appends a
* matching NXAST_LEARN action to 'b'. The format parsed is described in
* ovs-ofctl(8).
*
* Prints an error on stderr and aborts the program if 'arg' syntax is invalid.
*
* If 'flow' is nonnull, then it should be the flow from a cls_rule that is
* the matching rule for the learning action. This helps to better validate
* the action's arguments.
*
* Modifies 'arg'. */
void
learn_parse(struct ofpbuf *b, char *arg, const struct flow *flow)
{
char *orig = xstrdup(arg);
char *name, *value;
enum ofperr error;
size_t learn_ofs;
size_t len;
struct nx_action_learn *learn;
struct cls_rule rule;
learn_ofs = b->size;
learn = ofputil_put_NXAST_LEARN(b);
learn->idle_timeout = htons(OFP_FLOW_PERMANENT);
learn->hard_timeout = htons(OFP_FLOW_PERMANENT);
learn->priority = htons(OFP_DEFAULT_PRIORITY);
learn->cookie = htonll(0);
learn->flags = htons(0);
learn->table_id = 1;
cls_rule_init_catchall(&rule, 0);
while (ofputil_parse_key_value(&arg, &name, &value)) {
learn = ofpbuf_at_assert(b, learn_ofs, sizeof *learn);
if (!strcmp(name, "table")) {
learn->table_id = atoi(value);
if (learn->table_id == 255) {
ovs_fatal(0, "%s: table id 255 not valid for `learn' action",
orig);
}
} else if (!strcmp(name, "priority")) {
learn->priority = htons(atoi(value));
} else if (!strcmp(name, "idle_timeout")) {
learn->idle_timeout = htons(atoi(value));
} else if (!strcmp(name, "hard_timeout")) {
learn->hard_timeout = htons(atoi(value));
} else if (!strcmp(name, "cookie")) {
learn->cookie = htonll(strtoull(value, NULL, 0));
} else {
struct learn_spec spec;
learn_parse_spec(orig, name, value, &spec);
/* Check prerequisites. */
if (spec.src_type == NX_LEARN_SRC_FIELD
&& flow && !mf_are_prereqs_ok(spec.src.field, flow)) {
ovs_fatal(0, "%s: cannot specify source field %s because "
"prerequisites are not satisfied",
orig, spec.src.field->name);
}
if ((spec.dst_type == NX_LEARN_DST_MATCH
|| spec.dst_type == NX_LEARN_DST_LOAD)
&& !mf_are_prereqs_ok(spec.dst.field, &rule.flow)) {
ovs_fatal(0, "%s: cannot specify destination field %s because "
"prerequisites are not satisfied",
orig, spec.dst.field->name);
}
/* Update 'rule' to allow for satisfying destination
* prerequisites. */
if (spec.src_type == NX_LEARN_SRC_IMMEDIATE
&& spec.dst_type == NX_LEARN_DST_MATCH
&& spec.dst.ofs == 0
&& spec.n_bits == spec.dst.field->n_bytes * 8) {
union mf_value imm;
memcpy(&imm, spec.src_imm, spec.dst.field->n_bytes);
mf_set_value(spec.dst.field, &imm, &rule);
}
/* Output the flow_mod_spec. */
put_u16(b, spec.n_bits | spec.src_type | spec.dst_type);
if (spec.src_type == NX_LEARN_SRC_IMMEDIATE) {
int n_bytes = DIV_ROUND_UP(spec.n_bits, 8);
if (n_bytes % 2) {
ofpbuf_put_zeros(b, 1);
}
ofpbuf_put(b, spec.src_imm, n_bytes);
} else {
put_u32(b, spec.src.field->nxm_header);
put_u16(b, spec.src.ofs);
}
if (spec.dst_type == NX_LEARN_DST_MATCH ||
spec.dst_type == NX_LEARN_DST_LOAD) {
put_u32(b, spec.dst.field->nxm_header);
put_u16(b, spec.dst.ofs);
} else {
assert(spec.dst_type == NX_LEARN_DST_OUTPUT);
}
}
}
put_u16(b, 0);
len = b->size - learn_ofs;
if (len % 8) {
ofpbuf_put_zeros(b, 8 - len % 8);
}
learn = ofpbuf_at_assert(b, learn_ofs, sizeof *learn);
learn->len = htons(b->size - learn_ofs);
/* In theory the above should have caught any errors, but... */
if (flow) {
error = learn_check(learn, flow);
if (error) {
ovs_fatal(0, "%s: %s", orig, ofperr_to_string(error));
}
}
free(orig);
}
void
learn_format(const struct nx_action_learn *learn, struct ds *s)
{
struct cls_rule rule;
const void *p, *end;
cls_rule_init_catchall(&rule, 0);
ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
if (learn->idle_timeout != htons(OFP_FLOW_PERMANENT)) {
ds_put_format(s, ",idle_timeout=%"PRIu16, ntohs(learn->idle_timeout));
}
if (learn->hard_timeout != htons(OFP_FLOW_PERMANENT)) {
ds_put_format(s, ",hard_timeout=%"PRIu16, ntohs(learn->hard_timeout));
}
if (learn->priority != htons(OFP_DEFAULT_PRIORITY)) {
ds_put_format(s, ",priority=%"PRIu16, ntohs(learn->priority));
}
if (learn->flags & htons(OFPFF_SEND_FLOW_REM)) {
ds_put_cstr(s, ",OFPFF_SEND_FLOW_REM");
}
if (learn->flags & htons(~OFPFF_SEND_FLOW_REM)) {
ds_put_format(s, ",***flags=%"PRIu16"***",
ntohs(learn->flags) & ~OFPFF_SEND_FLOW_REM);
}
if (learn->cookie != htonll(0)) {
ds_put_format(s, ",cookie=0x%"PRIx64, ntohll(learn->cookie));
}
if (!is_all_zeros(learn->pad, sizeof learn->pad)) {
ds_put_cstr(s, ",***nonzero pad***");
}
end = (char *) learn + ntohs(learn->len);
for (p = learn + 1; p != end; ) {
uint16_t header = ntohs(get_be16(&p));
int n_bits = header & NX_LEARN_N_BITS_MASK;
int src_type = header & NX_LEARN_SRC_MASK;
struct mf_subfield src;
const uint8_t *src_value;
int src_value_bytes;
int dst_type = header & NX_LEARN_DST_MASK;
struct mf_subfield dst;
enum ofperr error;
int i;
if (!header) {
break;
}
error = learn_check_header(header, (char *) end - (char *) p);
if (error == OFPERR_OFPBAC_BAD_ARGUMENT) {
ds_put_format(s, ",***bad flow_mod_spec header %"PRIx16"***)",
header);
return;
} else if (error == OFPERR_OFPBAC_BAD_LEN) {
ds_put_format(s, ",***flow_mod_spec at offset %td is %u bytes "
"long but only %td bytes are left***)",
(char *) p - (char *) (learn + 1) - 2,
learn_min_len(header) + 2,
(char *) end - (char *) p + 2);
return;
}
assert(!error);
/* Get the source. */
if (src_type == NX_LEARN_SRC_FIELD) {
get_subfield(n_bits, &p, &src);
src_value_bytes = 0;
src_value = NULL;
} else {
src.field = NULL;
src.ofs = 0;
src.n_bits = 0;
src_value_bytes = 2 * DIV_ROUND_UP(n_bits, 16);
src_value = p;
p = (const void *) ((const uint8_t *) p + src_value_bytes);
}
/* Get the destination. */
if (dst_type == NX_LEARN_DST_MATCH || dst_type == NX_LEARN_DST_LOAD) {
get_subfield(n_bits, &p, &dst);
} else {
dst.field = NULL;
dst.ofs = 0;
dst.n_bits = 0;
}
ds_put_char(s, ',');
switch (src_type | dst_type) {
case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
if (dst.field && dst.ofs == 0 && n_bits == dst.field->n_bits) {
union mf_value value;
uint8_t *bytes = (uint8_t *) &value;
if (src_value_bytes > dst.field->n_bytes) {
/* The destination field is an odd number of bytes, which
* got rounded up to a multiple of 2 to be put into the
* learning action. Skip over the leading byte, which
* should be zero anyway. Otherwise the memcpy() below
* will overrun the start of 'value'. */
int diff = src_value_bytes - dst.field->n_bytes;
src_value += diff;
src_value_bytes -= diff;
}
memset(&value, 0, sizeof value);
memcpy(&bytes[dst.field->n_bytes - src_value_bytes],
src_value, src_value_bytes);
ds_put_format(s, "%s=", dst.field->name);
mf_format(dst.field, &value, NULL, s);
} else {
mf_format_subfield(&dst, s);
ds_put_cstr(s, "=0x");
for (i = 0; i < src_value_bytes; i++) {
ds_put_format(s, "%02"PRIx8, src_value[i]);
}
}
break;
case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
mf_format_subfield(&dst, s);
if (src.field != dst.field || src.ofs != dst.ofs) {
ds_put_char(s, '=');
mf_format_subfield(&src, s);
}
break;
case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
ds_put_cstr(s, "load:0x");
for (i = 0; i < src_value_bytes; i++) {
ds_put_format(s, "%02"PRIx8, src_value[i]);
}
ds_put_cstr(s, "->");
mf_format_subfield(&dst, s);
break;
case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
ds_put_cstr(s, "load:");
mf_format_subfield(&src, s);
ds_put_cstr(s, "->");
mf_format_subfield(&dst, s);
break;
case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
ds_put_cstr(s, "output:");
mf_format_subfield(&src, s);
break;
}
}
if (!is_all_zeros(p, (char *) end - (char *) p)) {
ds_put_cstr(s, ",***nonzero trailer***");
}
ds_put_char(s, ')');
}
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