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openvswitch/lib/learn.c
Ben Pfaff 90bf1e0732 Better abstract OpenFlow error codes. 
This commit switches from using the actual protocol values of error codes
internally in Open vSwitch, to using abstract values that are translated to
and from protocol values at message parsing and serialization time.  I
believe that this makes the code easier to read and to write.

This is also one step along the way toward OpenFlow 1.1 support because
OpenFlow 1.1 renumbered a bunch of error codes.

Signed-off-by: Ben Pfaff <blp@nicira.com>
2012-01-12 15:54:25 -08:00

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/*
* Copyright (c) 2011 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 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) {
ovs_be32 src_field = get_be32(&p);
int src_ofs = ntohs(get_be16(&p));
error = nxm_src_check(src_field, src_ofs, n_bits, 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) {
ovs_be32 dst_field = get_be32(&p);
int dst_ofs = ntohs(get_be16(&p));
error = (dst_type == NX_LEARN_DST_LOAD
? nxm_dst_check(dst_field, dst_ofs, n_bits, &rule.flow)
: nxm_src_check(dst_field, dst_ofs, n_bits, &rule.flow));
if (error) {
return error;
}
if (dst_type == NX_LEARN_DST_MATCH
&& src_type == NX_LEARN_SRC_IMMEDIATE) {
mf_set_subfield(mf_from_nxm_header(ntohl(dst_field)), value,
dst_ofs, n_bits, &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;
ovs_be32 dst_field;
int dst_ofs;
if (!header) {
break;
}
if (src_type == NX_LEARN_SRC_FIELD) {
ovs_be32 src_field = get_be32(&p);
int src_ofs = ntohs(get_be16(&p));
value = nxm_read_field_bits(src_field,
nxm_encode_ofs_nbits(src_ofs, n_bits),
flow);
} else {
value = get_bits(n_bits, &p);
}
switch (dst_type) {
case NX_LEARN_DST_MATCH:
dst_field = get_be32(&p);
dst_ofs = ntohs(get_be16(&p));
mf_set_subfield(mf_from_nxm_header(ntohl(dst_field)), value,
dst_ofs, n_bits, &fm->cr);
break;
case NX_LEARN_DST_LOAD:
dst_field = get_be32(&p);
dst_ofs = ntohs(get_be16(&p));
load = ofputil_put_NXAST_REG_LOAD(&actions);
load->ofs_nbits = nxm_encode_ofs_nbits(dst_ofs, n_bits);
load->dst = dst_field;
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;
const struct mf_field *src;
int src_ofs;
uint8_t src_imm[sizeof(union mf_value)];
int dst_type;
const struct mf_field *dst;
int dst_ofs;
};
static void
learn_parse_spec(const char *orig, char *name, char *value,
struct learn_spec *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;
spec->src = NULL;
spec->src_ofs = 0;
memcpy(spec->src_imm, &imm, dst->n_bytes);
spec->dst_type = NX_LEARN_DST_MATCH;
spec->dst = dst;
spec->dst_ofs = 0;
} else if (strchr(name, '[')) {
uint32_t src_header, dst_header;
int src_ofs, dst_ofs;
int n_bits;
/* Parse destination and check prerequisites. */
if (nxm_parse_field_bits(name, &dst_header, &dst_ofs,
&n_bits)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, name);
}
/* Parse source and check prerequisites. */
if (value[0] != '\0') {
int src_nbits;
if (nxm_parse_field_bits(value, &src_header, &src_ofs,
&src_nbits)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, value);
}
if (src_nbits != n_bits) {
ovs_fatal(0, "%s: bit widths of %s (%d) and %s (%d) differ",
orig, name, dst_header, value, dst_header);
}
} else {
src_header = dst_header;
src_ofs = dst_ofs;
}
spec->n_bits = n_bits;
spec->src_type = NX_LEARN_SRC_FIELD;
spec->src = mf_from_nxm_header(src_header);
spec->src_ofs = src_ofs;
spec->dst_type = NX_LEARN_DST_MATCH;
spec->dst = mf_from_nxm_header(dst_header);
spec->dst_ofs = 0;
} 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;
spec->src = NULL;
spec->src_ofs = 0;
for (i = 0; i < imm_bytes; i++) {
spec->src_imm[i] = imm >> ((imm_bytes - i - 1) * 8);
}
spec->dst_type = NX_LEARN_DST_LOAD;
spec->dst = mf_from_nxm_header(ntohl(load.dst));
spec->dst_ofs = nxm_decode_ofs(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;
spec->src = mf_from_nxm_header(ntohl(move.src));
spec->src_ofs = ntohs(move.src_ofs);
spec->dst_type = NX_LEARN_DST_LOAD;
spec->dst = mf_from_nxm_header(ntohl(move.dst));
spec->dst_ofs = ntohs(move.dst_ofs);
}
} else if (!strcmp(name, "output")) {
uint32_t header;
int ofs, n_bits;
if (nxm_parse_field_bits(value, &header, &ofs, &n_bits)[0] != '\0') {
ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
orig, name);
}
spec->n_bits = n_bits;
spec->src_type = NX_LEARN_SRC_FIELD;
spec->src = mf_from_nxm_header(header);
spec->src_ofs = ofs;
spec->dst_type = NX_LEARN_DST_OUTPUT;
spec->dst = NULL;
spec->dst_ofs = 0;
} else {
ovs_fatal(0, "%s: unknown keyword %s", orig, name);
}
}
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
&& !mf_are_prereqs_ok(spec.src, flow)) {
ovs_fatal(0, "%s: cannot specify source field %s because "
"prerequisites are not satisfied",
orig, spec.src->name);
}
if ((spec.dst_type == NX_LEARN_DST_MATCH
|| spec.dst_type == NX_LEARN_DST_LOAD)
&& !mf_are_prereqs_ok(spec.dst, &rule.flow)) {
ovs_fatal(0, "%s: cannot specify destination field %s because "
"prerequisites are not satisfied",
orig, spec.dst->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->n_bytes * 8) {
union mf_value imm;
memcpy(&imm, spec.src_imm, spec.dst->n_bytes);
mf_set_value(spec.dst, &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->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->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... */
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;
uint32_t src_header;
int src_ofs;
const uint8_t *src_value;
int src_value_bytes;
int dst_type = header & NX_LEARN_DST_MASK;
uint32_t dst_header;
int dst_ofs;
const struct mf_field *dst_field;
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) {
src_header = ntohl(get_be32(&p));
src_ofs = ntohs(get_be16(&p));
src_value_bytes = 0;
src_value = NULL;
} else {
src_header = 0;
src_ofs = 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) {
dst_header = ntohl(get_be32(&p));
dst_field = mf_from_nxm_header(dst_header);
dst_ofs = ntohs(get_be16(&p));
} else {
dst_header = 0;
dst_field = NULL;
dst_ofs = 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 {
nxm_format_field_bits(s, dst_header, dst_ofs, n_bits);
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:
nxm_format_field_bits(s, dst_header, dst_ofs, n_bits);
if (src_header != dst_header || src_ofs != dst_ofs) {
ds_put_char(s, '=');
nxm_format_field_bits(s, src_header, src_ofs, n_bits);
}
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, "->");
nxm_format_field_bits(s, dst_header, dst_ofs, n_bits);
break;
case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
ds_put_cstr(s, "load:");
nxm_format_field_bits(s, src_header, src_ofs, n_bits);
ds_put_cstr(s, "->");
nxm_format_field_bits(s, dst_header, dst_ofs, n_bits);
break;
case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
ds_put_cstr(s, "output:");
nxm_format_field_bits(s, src_header, src_ofs, n_bits);
break;
}
}
if (!is_all_zeros(p, (char *) end - (char *) p)) {
ds_put_cstr(s, ",***nonzero trailer***");
}
ds_put_char(s, ')');
}
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