lib/learn.c

   1 /*
   2  * Copyright (c) 2011, 2012 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "learn.h"
  20
  21 #include "byte-order.h"
  22 #include "dynamic-string.h"
  23 #include "meta-flow.h"
  24 #include "nx-match.h"
  25 #include "ofp-actions.h"
  26 #include "ofp-errors.h"
  27 #include "ofp-util.h"
  28 #include "ofpbuf.h"
  29 #include "openflow/openflow.h"
  30 #include "unaligned.h"
  31
  32 static ovs_be16
  33 get_be16(const void **pp)
  34 {
  35     const ovs_be16 *p = *pp;
  36     ovs_be16 value = *p;
  37     *pp = p + 1;
  38     return value;
  39 }
  40
  41 static ovs_be32
  42 get_be32(const void **pp)
  43 {
  44     const ovs_be32 *p = *pp;
  45     ovs_be32 value = get_unaligned_be32(p);
  46     *pp = p + 1;
  47     return value;
  48 }
  49
  50 static void
  51 get_subfield(int n_bits, const void **p, struct mf_subfield *sf)
  52 {
  53     sf->field = mf_from_nxm_header(ntohl(get_be32(p)));
  54     sf->ofs = ntohs(get_be16(p));
  55     sf->n_bits = n_bits;
  56 }
  57
  58 static unsigned int
  59 learn_min_len(uint16_t header)
  60 {
  61     int n_bits = header & NX_LEARN_N_BITS_MASK;
  62     int src_type = header & NX_LEARN_SRC_MASK;
  63     int dst_type = header & NX_LEARN_DST_MASK;
  64     unsigned int min_len;
  65
  66     min_len = 0;
  67     if (src_type == NX_LEARN_SRC_FIELD) {
  68         min_len += sizeof(ovs_be32); /* src_field */
  69         min_len += sizeof(ovs_be16); /* src_ofs */
  70     } else {
  71         min_len += DIV_ROUND_UP(n_bits, 16);
  72     }
  73     if (dst_type == NX_LEARN_DST_MATCH ||
  74         dst_type == NX_LEARN_DST_LOAD) {
  75         min_len += sizeof(ovs_be32); /* dst_field */
  76         min_len += sizeof(ovs_be16); /* dst_ofs */
  77     }
  78     return min_len;
  79 }
  80
  81 /* Converts 'nal' into a "struct ofpact_learn" and appends that struct to
  82  * 'ofpacts'.  Returns 0 if successful, otherwise an OFPERR_*. */
  83 enum ofperr
  84 learn_from_openflow(const struct nx_action_learn *nal, struct ofpbuf *ofpacts)
  85 {
  86     struct ofpact_learn *learn;
  87     const void *p, *end;
  88
  89     if (nal->pad) {
  90         return OFPERR_OFPBAC_BAD_ARGUMENT;
  91     }
  92
  93     learn = ofpact_put_LEARN(ofpacts);
  94
  95     learn->idle_timeout = ntohs(nal->idle_timeout);
  96     learn->hard_timeout = ntohs(nal->hard_timeout);
  97     learn->priority = ntohs(nal->priority);
  98     learn->cookie = ntohll(nal->cookie);
  99     learn->flags = ntohs(nal->flags);
 100     learn->table_id = nal->table_id;
 101     learn->fin_idle_timeout = ntohs(nal->fin_idle_timeout);
 102     learn->fin_hard_timeout = ntohs(nal->fin_hard_timeout);
 103
 104     if (learn->flags & ~OFPFF_SEND_FLOW_REM || learn->table_id == 0xff) {
 105         return OFPERR_OFPBAC_BAD_ARGUMENT;
 106     }
 107
 108     end = (char *) nal + ntohs(nal->len);
 109     for (p = nal + 1; p != end; ) {
 110         struct ofpact_learn_spec *spec;
 111         uint16_t header = ntohs(get_be16(&p));
 112
 113         if (!header) {
 114             break;
 115         }
 116
 117         spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 118         learn = ofpacts->l2;
 119         learn->n_specs++;
 120
 121         spec->src_type = header & NX_LEARN_SRC_MASK;
 122         spec->dst_type = header & NX_LEARN_DST_MASK;
 123         spec->n_bits = header & NX_LEARN_N_BITS_MASK;
 124
 125         /* Check for valid src and dst type combination. */
 126         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 127             spec->dst_type == NX_LEARN_DST_LOAD ||
 128             (spec->dst_type == NX_LEARN_DST_OUTPUT &&
 129              spec->src_type == NX_LEARN_SRC_FIELD)) {
 130             /* OK. */
 131         } else {
 132             return OFPERR_OFPBAC_BAD_ARGUMENT;
 133         }
 134
 135         /* Check that the arguments don't overrun the end of the action. */
 136         if ((char *) end - (char *) p < learn_min_len(header)) {
 137             return OFPERR_OFPBAC_BAD_LEN;
 138         }
 139
 140         /* Get the source. */
 141         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 142             get_subfield(spec->n_bits, &p, &spec->src);
 143         } else {
 144             int p_bytes = 2 * DIV_ROUND_UP(spec->n_bits, 16);
 145
 146             bitwise_copy(p, p_bytes, 0,
 147                          &spec->src_imm, sizeof spec->src_imm, 0,
 148                          spec->n_bits);
 149             p = (const uint8_t *) p + p_bytes;
 150         }
 151
 152         /* Get the destination. */
 153         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 154             spec->dst_type == NX_LEARN_DST_LOAD) {
 155             get_subfield(spec->n_bits, &p, &spec->dst);
 156         }
 157     }
 158     ofpact_update_len(ofpacts, &learn->ofpact);
 159
 160     if (!is_all_zeros(p, (char *) end - (char *) p)) {
 161         return OFPERR_OFPBAC_BAD_ARGUMENT;
 162     }
 163
 164     return 0;
 165 }
 166
 167 /* Checks that 'learn' is a valid action on 'flow'.  Returns 0 if it is valid,
 168  * otherwise an OFPERR_*. */
 169 enum ofperr
 170 learn_check(const struct ofpact_learn *learn, const struct flow *flow)
 171 {
 172     const struct ofpact_learn_spec *spec;
 173     struct cls_rule rule;
 174
 175     cls_rule_init_catchall(&rule, 0);
 176     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 177         enum ofperr error;
 178
 179         /* Check the source. */
 180         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 181             error = mf_check_src(&spec->src, flow);
 182             if (error) {
 183                 return error;
 184             }
 185         }
 186
 187         /* Check the destination. */
 188         switch (spec->dst_type) {
 189         case NX_LEARN_DST_MATCH:
 190             error = mf_check_src(&spec->dst, &rule.flow);
 191             if (error) {
 192                 return error;
 193             }
 194
 195             mf_write_subfield(&spec->dst, &spec->src_imm, &rule);
 196             break;
 197
 198         case NX_LEARN_DST_LOAD:
 199             error = mf_check_dst(&spec->dst, &rule.flow);
 200             if (error) {
 201                 return error;
 202             }
 203             break;
 204
 205         case NX_LEARN_DST_OUTPUT:
 206             /* Nothing to do. */
 207             break;
 208         }
 209     }
 210     return 0;
 211 }
 212
 213 static void
 214 put_be16(struct ofpbuf *b, ovs_be16 x)
 215 {
 216     ofpbuf_put(b, &x, sizeof x);
 217 }
 218
 219 static void
 220 put_be32(struct ofpbuf *b, ovs_be32 x)
 221 {
 222     ofpbuf_put(b, &x, sizeof x);
 223 }
 224
 225 static void
 226 put_u16(struct ofpbuf *b, uint16_t x)
 227 {
 228     put_be16(b, htons(x));
 229 }
 230
 231 static void
 232 put_u32(struct ofpbuf *b, uint32_t x)
 233 {
 234     put_be32(b, htonl(x));
 235 }
 236
 237 /* Converts 'learn' into a "struct nx_action_learn" and appends that action to
 238  * 'ofpacts'. */
 239 void
 240 learn_to_nxast(const struct ofpact_learn *learn, struct ofpbuf *openflow)
 241 {
 242     const struct ofpact_learn_spec *spec;
 243     struct nx_action_learn *nal;
 244     size_t start_ofs;
 245
 246     start_ofs = openflow->size;
 247     nal = ofputil_put_NXAST_LEARN(openflow);
 248     nal->idle_timeout = htons(learn->idle_timeout);
 249     nal->hard_timeout = htons(learn->hard_timeout);
 250     nal->fin_idle_timeout = htons(learn->fin_idle_timeout);
 251     nal->fin_hard_timeout = htons(learn->fin_hard_timeout);
 252     nal->priority = htons(learn->priority);
 253     nal->cookie = htonll(learn->cookie);
 254     nal->flags = htons(learn->flags);
 255     nal->table_id = learn->table_id;
 256
 257     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 258         put_u16(openflow, spec->n_bits | spec->dst_type | spec->src_type);
 259
 260         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 261             put_u32(openflow, spec->src.field->nxm_header);
 262             put_u16(openflow, spec->src.ofs);
 263         } else {
 264             size_t n_dst_bytes = 2 * DIV_ROUND_UP(spec->n_bits, 16);
 265             uint8_t *bits = ofpbuf_put_zeros(openflow, n_dst_bytes);
 266             bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 267                          bits, n_dst_bytes, 0,
 268                          spec->n_bits);
 269         }
 270
 271         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 272             spec->dst_type == NX_LEARN_DST_LOAD) {
 273             put_u32(openflow, spec->dst.field->nxm_header);
 274             put_u16(openflow, spec->dst.ofs);
 275         }
 276     }
 277
 278     if ((openflow->size - start_ofs) % 8) {
 279         ofpbuf_put_zeros(openflow, 8 - (openflow->size - start_ofs) % 8);
 280     }
 281
 282     nal = ofpbuf_at_assert(openflow, start_ofs, sizeof *nal);
 283     nal->len = htons(openflow->size - start_ofs);
 284 }
 285
 286 /* Composes 'fm' so that executing it will implement 'learn' given that the
 287  * packet being processed has 'flow' as its flow.
 288  *
 289  * Uses 'ofpacts' to store the flow mod's actions.  The caller must initialize
 290  * 'ofpacts' and retains ownership of it.  'fm->ofpacts' will point into the
 291  * 'ofpacts' buffer.
 292  *
 293  * The caller has to actually execute 'fm'. */
 294 void
 295 learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
 296               struct ofputil_flow_mod *fm, struct ofpbuf *ofpacts)
 297 {
 298     const struct ofpact_learn_spec *spec;
 299
 300     cls_rule_init_catchall(&fm->cr, learn->priority);
 301     fm->cookie = htonll(0);
 302     fm->cookie_mask = htonll(0);
 303     fm->new_cookie = htonll(learn->cookie);
 304     fm->table_id = learn->table_id;
 305     fm->command = OFPFC_MODIFY_STRICT;
 306     fm->idle_timeout = learn->idle_timeout;
 307     fm->hard_timeout = learn->hard_timeout;
 308     fm->buffer_id = UINT32_MAX;
 309     fm->out_port = OFPP_NONE;
 310     fm->flags = learn->flags;
 311     fm->ofpacts = NULL;
 312     fm->ofpacts_len = 0;
 313
 314     if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
 315         struct ofpact_fin_timeout *oft;
 316
 317         oft = ofpact_put_FIN_TIMEOUT(ofpacts);
 318         oft->fin_idle_timeout = learn->fin_idle_timeout;
 319         oft->fin_hard_timeout = learn->fin_hard_timeout;
 320     }
 321
 322     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 323         union mf_subvalue value;
 324         int chunk, ofs;
 325
 326         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 327             mf_read_subfield(&spec->src, flow, &value);
 328         } else {
 329             value = spec->src_imm;
 330         }
 331
 332         switch (spec->dst_type) {
 333         case NX_LEARN_DST_MATCH:
 334             mf_write_subfield(&spec->dst, &value, &fm->cr);
 335             break;
 336
 337         case NX_LEARN_DST_LOAD:
 338             for (ofs = 0; ofs < spec->n_bits; ofs += chunk) {
 339                 struct ofpact_reg_load *load;
 340                 ovs_be64 value_be;
 341
 342                 chunk = MIN(spec->n_bits - ofs, 64);
 343
 344                 load = ofpact_put_REG_LOAD(ofpacts);
 345                 load->dst.field = spec->dst.field;
 346                 load->dst.ofs = spec->dst.ofs + ofs;
 347                 load->dst.n_bits = chunk;
 348
 349                 memset(&value_be, 0, sizeof value_be);
 350                 bitwise_copy(&value, sizeof value, ofs,
 351                              &value_be, sizeof value_be, 0,
 352                              chunk);
 353                 load->value = ntohll(value_be);
 354             }
 355             break;
 356
 357         case NX_LEARN_DST_OUTPUT:
 358             if (spec->n_bits <= 16
 359                 || is_all_zeros(value.u8, sizeof value - 2)) {
 360                 uint16_t port = ntohs(value.be16[7]);
 361
 362                 if (port < OFPP_MAX
 363                     || port == OFPP_IN_PORT
 364                     || port == OFPP_FLOOD
 365                     || port == OFPP_LOCAL
 366                     || port == OFPP_ALL) {
 367                     ofpact_put_OUTPUT(ofpacts)->port = port;
 368                 }
 369             }
 370             break;
 371         }
 372     }
 373     ofpact_pad(ofpacts);
 374
 375     fm->ofpacts = ofpacts->data;
 376     fm->ofpacts_len = ofpacts->size;
 377 }
 378
 379 static void
 380 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 381 {
 382     const char *full_s = s;
 383     const char *arrow = strstr(s, "->");
 384     struct mf_subfield dst;
 385     union mf_subvalue imm;
 386
 387     memset(&imm, 0, sizeof imm);
 388     if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X') && arrow) {
 389         const char *in = arrow - 1;
 390         uint8_t *out = imm.u8 + sizeof imm.u8 - 1;
 391         int n = arrow - (s + 2);
 392         int i;
 393
 394         for (i = 0; i < n; i++) {
 395             int hexit = hexit_value(in[-i]);
 396             if (hexit < 0) {
 397                 ovs_fatal(0, "%s: bad hex digit in value", full_s);
 398             }
 399             out[-(i / 2)] |= i % 2 ? hexit << 4 : hexit;
 400         }
 401         s = arrow;
 402     } else {
 403         imm.be64[1] = htonll(strtoull(s, (char **) &s, 0));
 404     }
 405
 406     if (strncmp(s, "->", 2)) {
 407         ovs_fatal(0, "%s: missing `->' following value", full_s);
 408     }
 409     s += 2;
 410
 411     s = mf_parse_subfield(&dst, s);
 412     if (*s != '\0') {
 413         ovs_fatal(0, "%s: trailing garbage following destination", full_s);
 414     }
 415
 416     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 417                               (8 * sizeof imm) - dst.n_bits)) {
 418         ovs_fatal(0, "%s: value does not fit into %u bits",
 419                   full_s, dst.n_bits);
 420     }
 421
 422     spec->n_bits = dst.n_bits;
 423     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 424     spec->src_imm = imm;
 425     spec->dst_type = NX_LEARN_DST_LOAD;
 426     spec->dst = dst;
 427 }
 428
 429 static void
 430 learn_parse_spec(const char *orig, char *name, char *value,
 431                  struct ofpact_learn_spec *spec)
 432 {
 433     if (mf_from_name(name)) {
 434         const struct mf_field *dst = mf_from_name(name);
 435         union mf_value imm;
 436         char *error;
 437
 438         error = mf_parse_value(dst, value, &imm);
 439         if (error) {
 440             ovs_fatal(0, "%s", error);
 441         }
 442
 443         spec->n_bits = dst->n_bits;
 444         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 445         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 446         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 447                &imm, dst->n_bytes);
 448         spec->dst_type = NX_LEARN_DST_MATCH;
 449         spec->dst.field = dst;
 450         spec->dst.ofs = 0;
 451         spec->dst.n_bits = dst->n_bits;
 452     } else if (strchr(name, '[')) {
 453         /* Parse destination and check prerequisites. */
 454         if (mf_parse_subfield(&spec->dst, name)[0] != '\0') {
 455             ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
 456                       orig, name);
 457         }
 458
 459         /* Parse source and check prerequisites. */
 460         if (value[0] != '\0') {
 461             if (mf_parse_subfield(&spec->src, value)[0] != '\0') {
 462                 ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
 463                           orig, value);
 464             }
 465             if (spec->src.n_bits != spec->dst.n_bits) {
 466                 ovs_fatal(0, "%s: bit widths of %s (%u) and %s (%u) differ",
 467                           orig, name, spec->src.n_bits, value,
 468                           spec->dst.n_bits);
 469             }
 470         } else {
 471             spec->src = spec->dst;
 472         }
 473
 474         spec->n_bits = spec->src.n_bits;
 475         spec->src_type = NX_LEARN_SRC_FIELD;
 476         spec->dst_type = NX_LEARN_DST_MATCH;
 477     } else if (!strcmp(name, "load")) {
 478         if (value[strcspn(value, "[-")] == '-') {
 479             learn_parse_load_immediate(value, spec);
 480         } else {
 481             struct ofpact_reg_move move;
 482
 483             nxm_parse_reg_move(&move, value);
 484
 485             spec->n_bits = move.src.n_bits;
 486             spec->src_type = NX_LEARN_SRC_FIELD;
 487             spec->src = move.src;
 488             spec->dst_type = NX_LEARN_DST_LOAD;
 489             spec->dst = move.dst;
 490         }
 491     } else if (!strcmp(name, "output")) {
 492         if (mf_parse_subfield(&spec->src, value)[0] != '\0') {
 493             ovs_fatal(0, "%s: syntax error after NXM field name `%s'",
 494                       orig, name);
 495         }
 496
 497         spec->n_bits = spec->src.n_bits;
 498         spec->src_type = NX_LEARN_SRC_FIELD;
 499         spec->dst_type = NX_LEARN_DST_OUTPUT;
 500     } else {
 501         ovs_fatal(0, "%s: unknown keyword %s", orig, name);
 502     }
 503 }
 504
 505 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 506  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 507  * format parsed.
 508  *
 509  * Prints an error on stderr and aborts the program if 'arg' syntax is invalid.
 510  *
 511  * If 'flow' is nonnull, then it should be the flow from a cls_rule that is
 512  * the matching rule for the learning action.  This helps to better validate
 513  * the action's arguments.
 514  *
 515  * Modifies 'arg'. */
 516 void
 517 learn_parse(char *arg, const struct flow *flow, struct ofpbuf *ofpacts)
 518 {
 519     char *orig = xstrdup(arg);
 520     char *name, *value;
 521
 522     struct ofpact_learn *learn;
 523     struct cls_rule rule;
 524     enum ofperr error;
 525
 526     learn = ofpact_put_LEARN(ofpacts);
 527     learn->idle_timeout = OFP_FLOW_PERMANENT;
 528     learn->hard_timeout = OFP_FLOW_PERMANENT;
 529     learn->priority = OFP_DEFAULT_PRIORITY;
 530     learn->table_id = 1;
 531
 532     cls_rule_init_catchall(&rule, 0);
 533     while (ofputil_parse_key_value(&arg, &name, &value)) {
 534         if (!strcmp(name, "table")) {
 535             learn->table_id = atoi(value);
 536             if (learn->table_id == 255) {
 537                 ovs_fatal(0, "%s: table id 255 not valid for `learn' action",
 538                           orig);
 539             }
 540         } else if (!strcmp(name, "priority")) {
 541             learn->priority = atoi(value);
 542         } else if (!strcmp(name, "idle_timeout")) {
 543             learn->idle_timeout = atoi(value);
 544         } else if (!strcmp(name, "hard_timeout")) {
 545             learn->hard_timeout = atoi(value);
 546         } else if (!strcmp(name, "fin_idle_timeout")) {
 547             learn->fin_idle_timeout = atoi(value);
 548         } else if (!strcmp(name, "fin_hard_timeout")) {
 549             learn->fin_hard_timeout = atoi(value);
 550         } else if (!strcmp(name, "cookie")) {
 551             learn->cookie = strtoull(value, NULL, 0);
 552         } else {
 553             struct ofpact_learn_spec *spec;
 554
 555             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 556             learn = ofpacts->l2;
 557             learn->n_specs++;
 558
 559             learn_parse_spec(orig, name, value, spec);
 560
 561             /* Check prerequisites. */
 562             if (spec->src_type == NX_LEARN_SRC_FIELD
 563                 && flow && !mf_are_prereqs_ok(spec->src.field, flow)) {
 564                 ovs_fatal(0, "%s: cannot specify source field %s because "
 565                           "prerequisites are not satisfied",
 566                           orig, spec->src.field->name);
 567             }
 568             if ((spec->dst_type == NX_LEARN_DST_MATCH
 569                  || spec->dst_type == NX_LEARN_DST_LOAD)
 570                 && !mf_are_prereqs_ok(spec->dst.field, &rule.flow)) {
 571                 ovs_fatal(0, "%s: cannot specify destination field %s because "
 572                           "prerequisites are not satisfied",
 573                           orig, spec->dst.field->name);
 574             }
 575
 576             /* Update 'rule' to allow for satisfying destination
 577              * prerequisites. */
 578             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 579                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 580                 mf_write_subfield(&spec->dst, &spec->src_imm, &rule);
 581             }
 582         }
 583     }
 584     ofpact_update_len(ofpacts, &learn->ofpact);
 585
 586     /* In theory the above should have caught any errors, but... */
 587     if (flow) {
 588         error = learn_check(learn, flow);
 589         if (error) {
 590             ovs_fatal(0, "%s: %s", orig, ofperr_to_string(error));
 591         }
 592     }
 593     free(orig);
 594 }
 595
 596 static void
 597 format_subvalue(const union mf_subvalue *subvalue, struct ds *s)
 598 {
 599     int i;
 600
 601     for (i = 0; i < ARRAY_SIZE(subvalue->u8); i++) {
 602         if (subvalue->u8[i]) {
 603             ds_put_format(s, "0x%"PRIx8, subvalue->u8[i]);
 604             for (i++; i < ARRAY_SIZE(subvalue->u8); i++) {
 605                 ds_put_format(s, "%02"PRIx8, subvalue->u8[i]);
 606             }
 607             return;
 608         }
 609     }
 610     ds_put_char(s, '0');
 611 }
 612
 613 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 614  * describes. */
 615 void
 616 learn_format(const struct ofpact_learn *learn, struct ds *s)
 617 {
 618     const struct ofpact_learn_spec *spec;
 619     struct cls_rule rule;
 620
 621     cls_rule_init_catchall(&rule, 0);
 622
 623     ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
 624     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 625         ds_put_format(s, ",idle_timeout=%"PRIu16, learn->idle_timeout);
 626     }
 627     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 628         ds_put_format(s, ",hard_timeout=%"PRIu16, learn->hard_timeout);
 629     }
 630     if (learn->fin_idle_timeout) {
 631         ds_put_format(s, ",fin_idle_timeout=%"PRIu16, learn->fin_idle_timeout);
 632     }
 633     if (learn->fin_hard_timeout) {
 634         ds_put_format(s, ",fin_hard_timeout=%"PRIu16, learn->fin_hard_timeout);
 635     }
 636     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 637         ds_put_format(s, ",priority=%"PRIu16, learn->priority);
 638     }
 639     if (learn->flags & OFPFF_SEND_FLOW_REM) {
 640         ds_put_cstr(s, ",OFPFF_SEND_FLOW_REM");
 641     }
 642     if (learn->cookie != 0) {
 643         ds_put_format(s, ",cookie=%#"PRIx64, learn->cookie);
 644     }
 645
 646     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 647         ds_put_char(s, ',');
 648
 649         switch (spec->src_type | spec->dst_type) {
 650         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 651             if (spec->dst.ofs == 0
 652                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 653                 union mf_value value;
 654
 655                 memset(&value, 0, sizeof value);
 656                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 657                              &value, spec->dst.field->n_bytes, 0,
 658                              spec->dst.field->n_bits);
 659                 ds_put_format(s, "%s=", spec->dst.field->name);
 660                 mf_format(spec->dst.field, &value, NULL, s);
 661             } else {
 662                 mf_format_subfield(&spec->dst, s);
 663                 ds_put_char(s, '=');
 664                 format_subvalue(&spec->src_imm, s);
 665             }
 666             break;
 667
 668         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 669             mf_format_subfield(&spec->dst, s);
 670             if (spec->src.field != spec->dst.field ||
 671                 spec->src.ofs != spec->dst.ofs) {
 672                 ds_put_char(s, '=');
 673                 mf_format_subfield(&spec->src, s);
 674             }
 675             break;
 676
 677         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 678             ds_put_format(s, "load:");
 679             format_subvalue(&spec->src_imm, s);
 680             ds_put_cstr(s, "->");
 681             mf_format_subfield(&spec->dst, s);
 682             break;
 683
 684         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 685             ds_put_cstr(s, "load:");
 686             mf_format_subfield(&spec->src, s);
 687             ds_put_cstr(s, "->");
 688             mf_format_subfield(&spec->dst, s);
 689             break;
 690
 691         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 692             ds_put_cstr(s, "output:");
 693             mf_format_subfield(&spec->src, s);
 694             break;
 695         }
 696     }
 697     ds_put_char(s, ')');
 698 }