lib/learn.c

   1 /*
   2  * Copyright (c) 2011, 2012, 2013 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 "match.h"
  24 #include "meta-flow.h"
  25 #include "nx-match.h"
  26 #include "ofp-actions.h"
  27 #include "ofp-errors.h"
  28 #include "ofp-util.h"
  29 #include "ofpbuf.h"
  30 #include "openflow/openflow.h"
  31 #include "unaligned.h"
  32
  33 static ovs_be16
  34 get_be16(const void **pp)
  35 {
  36     const ovs_be16 *p = *pp;
  37     ovs_be16 value = *p;
  38     *pp = p + 1;
  39     return value;
  40 }
  41
  42 static ovs_be32
  43 get_be32(const void **pp)
  44 {
  45     const ovs_be32 *p = *pp;
  46     ovs_be32 value = get_unaligned_be32(p);
  47     *pp = p + 1;
  48     return value;
  49 }
  50
  51 static void
  52 get_subfield(int n_bits, const void **p, struct mf_subfield *sf)
  53 {
  54     sf->field = mf_from_nxm_header(ntohl(get_be32(p)));
  55     sf->ofs = ntohs(get_be16(p));
  56     sf->n_bits = n_bits;
  57 }
  58
  59 static unsigned int
  60 learn_min_len(uint16_t header)
  61 {
  62     int n_bits = header & NX_LEARN_N_BITS_MASK;
  63     int src_type = header & NX_LEARN_SRC_MASK;
  64     int dst_type = header & NX_LEARN_DST_MASK;
  65     unsigned int min_len;
  66
  67     min_len = 0;
  68     if (src_type == NX_LEARN_SRC_FIELD) {
  69         min_len += sizeof(ovs_be32); /* src_field */
  70         min_len += sizeof(ovs_be16); /* src_ofs */
  71     } else {
  72         min_len += DIV_ROUND_UP(n_bits, 16);
  73     }
  74     if (dst_type == NX_LEARN_DST_MATCH ||
  75         dst_type == NX_LEARN_DST_LOAD) {
  76         min_len += sizeof(ovs_be32); /* dst_field */
  77         min_len += sizeof(ovs_be16); /* dst_ofs */
  78     }
  79     return min_len;
  80 }
  81
  82 /* Converts 'nal' into a "struct ofpact_learn" and appends that struct to
  83  * 'ofpacts'.  Returns 0 if successful, otherwise an OFPERR_*. */
  84 enum ofperr
  85 learn_from_openflow(const struct nx_action_learn *nal, struct ofpbuf *ofpacts)
  86 {
  87     struct ofpact_learn *learn;
  88     const void *p, *end;
  89
  90     if (nal->pad) {
  91         return OFPERR_OFPBAC_BAD_ARGUMENT;
  92     }
  93
  94     learn = ofpact_put_LEARN(ofpacts);
  95
  96     learn->idle_timeout = ntohs(nal->idle_timeout);
  97     learn->hard_timeout = ntohs(nal->hard_timeout);
  98     learn->priority = ntohs(nal->priority);
  99     learn->cookie = ntohll(nal->cookie);
 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     /* We only support "send-flow-removed" for now. */
 105     switch (ntohs(nal->flags)) {
 106     case 0:
 107         learn->flags = 0;
 108         break;
 109     case OFPFF_SEND_FLOW_REM:
 110         learn->flags = OFPUTIL_FF_SEND_FLOW_REM;
 111         break;
 112     default:
 113         return OFPERR_OFPBAC_BAD_ARGUMENT;
 114     }
 115
 116     if (learn->table_id == 0xff) {
 117         return OFPERR_OFPBAC_BAD_ARGUMENT;
 118     }
 119
 120     end = (char *) nal + ntohs(nal->len);
 121     for (p = nal + 1; p != end; ) {
 122         struct ofpact_learn_spec *spec;
 123         uint16_t header = ntohs(get_be16(&p));
 124
 125         if (!header) {
 126             break;
 127         }
 128
 129         spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 130         learn = ofpacts->frame;
 131         learn->n_specs++;
 132
 133         spec->src_type = header & NX_LEARN_SRC_MASK;
 134         spec->dst_type = header & NX_LEARN_DST_MASK;
 135         spec->n_bits = header & NX_LEARN_N_BITS_MASK;
 136
 137         /* Check for valid src and dst type combination. */
 138         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 139             spec->dst_type == NX_LEARN_DST_LOAD ||
 140             (spec->dst_type == NX_LEARN_DST_OUTPUT &&
 141              spec->src_type == NX_LEARN_SRC_FIELD)) {
 142             /* OK. */
 143         } else {
 144             return OFPERR_OFPBAC_BAD_ARGUMENT;
 145         }
 146
 147         /* Check that the arguments don't overrun the end of the action. */
 148         if ((char *) end - (char *) p < learn_min_len(header)) {
 149             return OFPERR_OFPBAC_BAD_LEN;
 150         }
 151
 152         /* Get the source. */
 153         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 154             get_subfield(spec->n_bits, &p, &spec->src);
 155         } else {
 156             int p_bytes = 2 * DIV_ROUND_UP(spec->n_bits, 16);
 157
 158             bitwise_copy(p, p_bytes, 0,
 159                          &spec->src_imm, sizeof spec->src_imm, 0,
 160                          spec->n_bits);
 161             p = (const uint8_t *) p + p_bytes;
 162         }
 163
 164         /* Get the destination. */
 165         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 166             spec->dst_type == NX_LEARN_DST_LOAD) {
 167             get_subfield(spec->n_bits, &p, &spec->dst);
 168         }
 169     }
 170     ofpact_update_len(ofpacts, &learn->ofpact);
 171
 172     if (!is_all_zeros(p, (char *) end - (char *) p)) {
 173         return OFPERR_OFPBAC_BAD_ARGUMENT;
 174     }
 175
 176     return 0;
 177 }
 178
 179 /* Checks that 'learn' is a valid action on 'flow'.  Returns 0 if it is valid,
 180  * otherwise an OFPERR_*. */
 181 enum ofperr
 182 learn_check(const struct ofpact_learn *learn, const struct flow *flow)
 183 {
 184     const struct ofpact_learn_spec *spec;
 185     struct match match;
 186
 187     match_init_catchall(&match);
 188     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 189         enum ofperr error;
 190
 191         /* Check the source. */
 192         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 193             error = mf_check_src(&spec->src, flow);
 194             if (error) {
 195                 return error;
 196             }
 197         }
 198
 199         /* Check the destination. */
 200         switch (spec->dst_type) {
 201         case NX_LEARN_DST_MATCH:
 202             error = mf_check_src(&spec->dst, &match.flow);
 203             if (error) {
 204                 return error;
 205             }
 206
 207             mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 208             break;
 209
 210         case NX_LEARN_DST_LOAD:
 211             error = mf_check_dst(&spec->dst, &match.flow);
 212             if (error) {
 213                 return error;
 214             }
 215             break;
 216
 217         case NX_LEARN_DST_OUTPUT:
 218             /* Nothing to do. */
 219             break;
 220         }
 221     }
 222     return 0;
 223 }
 224
 225 static void
 226 put_be16(struct ofpbuf *b, ovs_be16 x)
 227 {
 228     ofpbuf_put(b, &x, sizeof x);
 229 }
 230
 231 static void
 232 put_be32(struct ofpbuf *b, ovs_be32 x)
 233 {
 234     ofpbuf_put(b, &x, sizeof x);
 235 }
 236
 237 static void
 238 put_u16(struct ofpbuf *b, uint16_t x)
 239 {
 240     put_be16(b, htons(x));
 241 }
 242
 243 static void
 244 put_u32(struct ofpbuf *b, uint32_t x)
 245 {
 246     put_be32(b, htonl(x));
 247 }
 248
 249 /* Converts 'learn' into a "struct nx_action_learn" and appends that action to
 250  * 'ofpacts'. */
 251 void
 252 learn_to_nxast(const struct ofpact_learn *learn, struct ofpbuf *openflow)
 253 {
 254     const struct ofpact_learn_spec *spec;
 255     struct nx_action_learn *nal;
 256     size_t start_ofs;
 257
 258     start_ofs = ofpbuf_size(openflow);
 259     nal = ofputil_put_NXAST_LEARN(openflow);
 260     nal->idle_timeout = htons(learn->idle_timeout);
 261     nal->hard_timeout = htons(learn->hard_timeout);
 262     nal->fin_idle_timeout = htons(learn->fin_idle_timeout);
 263     nal->fin_hard_timeout = htons(learn->fin_hard_timeout);
 264     nal->priority = htons(learn->priority);
 265     nal->cookie = htonll(learn->cookie);
 266     nal->flags = htons(learn->flags);
 267     nal->table_id = learn->table_id;
 268
 269     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 270         put_u16(openflow, spec->n_bits | spec->dst_type | spec->src_type);
 271
 272         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 273             put_u32(openflow, spec->src.field->nxm_header);
 274             put_u16(openflow, spec->src.ofs);
 275         } else {
 276             size_t n_dst_bytes = 2 * DIV_ROUND_UP(spec->n_bits, 16);
 277             uint8_t *bits = ofpbuf_put_zeros(openflow, n_dst_bytes);
 278             bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 279                          bits, n_dst_bytes, 0,
 280                          spec->n_bits);
 281         }
 282
 283         if (spec->dst_type == NX_LEARN_DST_MATCH ||
 284             spec->dst_type == NX_LEARN_DST_LOAD) {
 285             put_u32(openflow, spec->dst.field->nxm_header);
 286             put_u16(openflow, spec->dst.ofs);
 287         }
 288     }
 289
 290     if ((ofpbuf_size(openflow) - start_ofs) % 8) {
 291         ofpbuf_put_zeros(openflow, 8 - (ofpbuf_size(openflow) - start_ofs) % 8);
 292     }
 293
 294     nal = ofpbuf_at_assert(openflow, start_ofs, sizeof *nal);
 295     nal->len = htons(ofpbuf_size(openflow) - start_ofs);
 296 }
 297
 298 /* Composes 'fm' so that executing it will implement 'learn' given that the
 299  * packet being processed has 'flow' as its flow.
 300  *
 301  * Uses 'ofpacts' to store the flow mod's actions.  The caller must initialize
 302  * 'ofpacts' and retains ownership of it.  'fm->ofpacts' will point into the
 303  * 'ofpacts' buffer.
 304  *
 305  * The caller has to actually execute 'fm'. */
 306 void
 307 learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
 308               struct ofputil_flow_mod *fm, struct ofpbuf *ofpacts)
 309 {
 310     const struct ofpact_learn_spec *spec;
 311
 312     match_init_catchall(&fm->match);
 313     fm->priority = learn->priority;
 314     fm->cookie = htonll(0);
 315     fm->cookie_mask = htonll(0);
 316     fm->new_cookie = htonll(learn->cookie);
 317     fm->modify_cookie = fm->new_cookie != OVS_BE64_MAX;
 318     fm->table_id = learn->table_id;
 319     fm->command = OFPFC_MODIFY_STRICT;
 320     fm->idle_timeout = learn->idle_timeout;
 321     fm->hard_timeout = learn->hard_timeout;
 322     fm->buffer_id = UINT32_MAX;
 323     fm->out_port = OFPP_NONE;
 324     fm->flags = learn->flags;
 325     fm->ofpacts = NULL;
 326     fm->ofpacts_len = 0;
 327
 328     if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
 329         struct ofpact_fin_timeout *oft;
 330
 331         oft = ofpact_put_FIN_TIMEOUT(ofpacts);
 332         oft->fin_idle_timeout = learn->fin_idle_timeout;
 333         oft->fin_hard_timeout = learn->fin_hard_timeout;
 334     }
 335
 336     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 337         union mf_subvalue value;
 338         int chunk, ofs;
 339
 340         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 341             mf_read_subfield(&spec->src, flow, &value);
 342         } else {
 343             value = spec->src_imm;
 344         }
 345
 346         switch (spec->dst_type) {
 347         case NX_LEARN_DST_MATCH:
 348             mf_write_subfield(&spec->dst, &value, &fm->match);
 349             break;
 350
 351         case NX_LEARN_DST_LOAD:
 352             for (ofs = 0; ofs < spec->n_bits; ofs += chunk) {
 353                 struct ofpact_reg_load *load;
 354
 355                 chunk = MIN(spec->n_bits - ofs, 64);
 356
 357                 load = ofpact_put_REG_LOAD(ofpacts);
 358                 load->dst.field = spec->dst.field;
 359                 load->dst.ofs = spec->dst.ofs + ofs;
 360                 load->dst.n_bits = chunk;
 361                 bitwise_copy(&value, sizeof value, ofs,
 362                              &load->subvalue, sizeof load->subvalue, 0,
 363                              chunk);
 364             }
 365             break;
 366
 367         case NX_LEARN_DST_OUTPUT:
 368             if (spec->n_bits <= 16
 369                 || is_all_zeros(value.u8, sizeof value - 2)) {
 370                 ofp_port_t port = u16_to_ofp(ntohs(value.be16[7]));
 371
 372                 if (ofp_to_u16(port) < ofp_to_u16(OFPP_MAX)
 373                     || port == OFPP_IN_PORT
 374                     || port == OFPP_FLOOD
 375                     || port == OFPP_LOCAL
 376                     || port == OFPP_ALL) {
 377                     ofpact_put_OUTPUT(ofpacts)->port = port;
 378                 }
 379             }
 380             break;
 381         }
 382     }
 383     ofpact_pad(ofpacts);
 384
 385     fm->ofpacts = ofpbuf_data(ofpacts);
 386     fm->ofpacts_len = ofpbuf_size(ofpacts);
 387 }
 388
 389 /* Perform a bitwise-OR on 'wc''s fields that are relevant as sources in
 390  * the learn action 'learn'. */
 391 void
 392 learn_mask(const struct ofpact_learn *learn, struct flow_wildcards *wc)
 393 {
 394     const struct ofpact_learn_spec *spec;
 395     union mf_subvalue value;
 396
 397     memset(&value, 0xff, sizeof value);
 398     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 399         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 400             mf_write_subfield_flow(&spec->src, &value, &wc->masks);
 401         }
 402     }
 403 }
 404
 405 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 406  * error.  The caller is responsible for freeing the returned string. */
 407 static char * WARN_UNUSED_RESULT
 408 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 409 {
 410     const char *full_s = s;
 411     const char *arrow = strstr(s, "->");
 412     struct mf_subfield dst;
 413     union mf_subvalue imm;
 414     char *error;
 415
 416     memset(&imm, 0, sizeof imm);
 417     if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X') && arrow) {
 418         const char *in = arrow - 1;
 419         uint8_t *out = imm.u8 + sizeof imm.u8 - 1;
 420         int n = arrow - (s + 2);
 421         int i;
 422
 423         for (i = 0; i < n; i++) {
 424             int hexit = hexit_value(in[-i]);
 425             if (hexit < 0) {
 426                 return xasprintf("%s: bad hex digit in value", full_s);
 427             }
 428             out[-(i / 2)] |= i % 2 ? hexit << 4 : hexit;
 429         }
 430         s = arrow;
 431     } else {
 432         imm.be64[1] = htonll(strtoull(s, (char **) &s, 0));
 433     }
 434
 435     if (strncmp(s, "->", 2)) {
 436         return xasprintf("%s: missing `->' following value", full_s);
 437     }
 438     s += 2;
 439
 440     error = mf_parse_subfield(&dst, s);
 441     if (error) {
 442         return error;
 443     }
 444
 445     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 446                               (8 * sizeof imm) - dst.n_bits)) {
 447         return xasprintf("%s: value does not fit into %u bits",
 448                          full_s, dst.n_bits);
 449     }
 450
 451     spec->n_bits = dst.n_bits;
 452     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 453     spec->src_imm = imm;
 454     spec->dst_type = NX_LEARN_DST_LOAD;
 455     spec->dst = dst;
 456     return NULL;
 457 }
 458
 459 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 460  * error.  The caller is responsible for freeing the returned string. */
 461 static char * WARN_UNUSED_RESULT
 462 learn_parse_spec(const char *orig, char *name, char *value,
 463                  struct ofpact_learn_spec *spec)
 464 {
 465     if (mf_from_name(name)) {
 466         const struct mf_field *dst = mf_from_name(name);
 467         union mf_value imm;
 468         char *error;
 469
 470         error = mf_parse_value(dst, value, &imm);
 471         if (error) {
 472             return error;
 473         }
 474
 475         spec->n_bits = dst->n_bits;
 476         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 477         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 478         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 479                &imm, dst->n_bytes);
 480         spec->dst_type = NX_LEARN_DST_MATCH;
 481         spec->dst.field = dst;
 482         spec->dst.ofs = 0;
 483         spec->dst.n_bits = dst->n_bits;
 484     } else if (strchr(name, '[')) {
 485         /* Parse destination and check prerequisites. */
 486         char *error;
 487
 488         error = mf_parse_subfield(&spec->dst, name);
 489         if (error) {
 490             return error;
 491         }
 492
 493         /* Parse source and check prerequisites. */
 494         if (value[0] != '\0') {
 495             error = mf_parse_subfield(&spec->src, value);
 496             if (error) {
 497                 return error;
 498             }
 499             if (spec->src.n_bits != spec->dst.n_bits) {
 500                 return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
 501                                  "differ", orig, name, spec->src.n_bits, value,
 502                                  spec->dst.n_bits);
 503             }
 504         } else {
 505             spec->src = spec->dst;
 506         }
 507
 508         spec->n_bits = spec->src.n_bits;
 509         spec->src_type = NX_LEARN_SRC_FIELD;
 510         spec->dst_type = NX_LEARN_DST_MATCH;
 511     } else if (!strcmp(name, "load")) {
 512         if (value[strcspn(value, "[-")] == '-') {
 513             char *error = learn_parse_load_immediate(value, spec);
 514             if (error) {
 515                 return error;
 516             }
 517         } else {
 518             struct ofpact_reg_move move;
 519             char *error;
 520
 521             error = nxm_parse_reg_move(&move, value);
 522             if (error) {
 523                 return error;
 524             }
 525
 526             spec->n_bits = move.src.n_bits;
 527             spec->src_type = NX_LEARN_SRC_FIELD;
 528             spec->src = move.src;
 529             spec->dst_type = NX_LEARN_DST_LOAD;
 530             spec->dst = move.dst;
 531         }
 532     } else if (!strcmp(name, "output")) {
 533         char *error = mf_parse_subfield(&spec->src, value);
 534         if (error) {
 535             return error;
 536         }
 537
 538         spec->n_bits = spec->src.n_bits;
 539         spec->src_type = NX_LEARN_SRC_FIELD;
 540         spec->dst_type = NX_LEARN_DST_OUTPUT;
 541     } else {
 542         return xasprintf("%s: unknown keyword %s", orig, name);
 543     }
 544
 545     return NULL;
 546 }
 547
 548 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 549  * error.  The caller is responsible for freeing the returned string. */
 550 static char * WARN_UNUSED_RESULT
 551 learn_parse__(char *orig, char *arg, struct ofpbuf *ofpacts)
 552 {
 553     struct ofpact_learn *learn;
 554     struct match match;
 555     char *name, *value;
 556
 557     learn = ofpact_put_LEARN(ofpacts);
 558     learn->idle_timeout = OFP_FLOW_PERMANENT;
 559     learn->hard_timeout = OFP_FLOW_PERMANENT;
 560     learn->priority = OFP_DEFAULT_PRIORITY;
 561     learn->table_id = 1;
 562
 563     match_init_catchall(&match);
 564     while (ofputil_parse_key_value(&arg, &name, &value)) {
 565         if (!strcmp(name, "table")) {
 566             learn->table_id = atoi(value);
 567             if (learn->table_id == 255) {
 568                 return xasprintf("%s: table id 255 not valid for `learn' "
 569                                  "action", orig);
 570             }
 571         } else if (!strcmp(name, "priority")) {
 572             learn->priority = atoi(value);
 573         } else if (!strcmp(name, "idle_timeout")) {
 574             learn->idle_timeout = atoi(value);
 575         } else if (!strcmp(name, "hard_timeout")) {
 576             learn->hard_timeout = atoi(value);
 577         } else if (!strcmp(name, "fin_idle_timeout")) {
 578             learn->fin_idle_timeout = atoi(value);
 579         } else if (!strcmp(name, "fin_hard_timeout")) {
 580             learn->fin_hard_timeout = atoi(value);
 581         } else if (!strcmp(name, "cookie")) {
 582             learn->cookie = strtoull(value, NULL, 0);
 583         } else {
 584             struct ofpact_learn_spec *spec;
 585             char *error;
 586
 587             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 588             learn = ofpacts->frame;
 589             learn->n_specs++;
 590
 591             error = learn_parse_spec(orig, name, value, spec);
 592             if (error) {
 593                 return error;
 594             }
 595
 596             /* Update 'match' to allow for satisfying destination
 597              * prerequisites. */
 598             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 599                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 600                 mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 601             }
 602         }
 603     }
 604     ofpact_update_len(ofpacts, &learn->ofpact);
 605
 606     return NULL;
 607 }
 608
 609 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 610  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 611  * format parsed.
 612  *
 613  * Returns NULL if successful, otherwise a malloc()'d string describing the
 614  * error.  The caller is responsible for freeing the returned string.
 615  *
 616  * If 'flow' is nonnull, then it should be the flow from a struct match that is
 617  * the matching rule for the learning action.  This helps to better validate
 618  * the action's arguments.
 619  *
 620  * Modifies 'arg'. */
 621 char * WARN_UNUSED_RESULT
 622 learn_parse(char *arg, struct ofpbuf *ofpacts)
 623 {
 624     char *orig = xstrdup(arg);
 625     char *error = learn_parse__(orig, arg, ofpacts);
 626     free(orig);
 627     return error;
 628 }
 629
 630 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 631  * describes. */
 632 void
 633 learn_format(const struct ofpact_learn *learn, struct ds *s)
 634 {
 635     const struct ofpact_learn_spec *spec;
 636     struct match match;
 637
 638     match_init_catchall(&match);
 639
 640     ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
 641     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 642         ds_put_format(s, ",idle_timeout=%"PRIu16, learn->idle_timeout);
 643     }
 644     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 645         ds_put_format(s, ",hard_timeout=%"PRIu16, learn->hard_timeout);
 646     }
 647     if (learn->fin_idle_timeout) {
 648         ds_put_format(s, ",fin_idle_timeout=%"PRIu16, learn->fin_idle_timeout);
 649     }
 650     if (learn->fin_hard_timeout) {
 651         ds_put_format(s, ",fin_hard_timeout=%"PRIu16, learn->fin_hard_timeout);
 652     }
 653     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 654         ds_put_format(s, ",priority=%"PRIu16, learn->priority);
 655     }
 656     if (learn->flags & OFPFF_SEND_FLOW_REM) {
 657         ds_put_cstr(s, ",OFPFF_SEND_FLOW_REM");
 658     }
 659     if (learn->cookie != 0) {
 660         ds_put_format(s, ",cookie=%#"PRIx64, learn->cookie);
 661     }
 662
 663     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 664         ds_put_char(s, ',');
 665
 666         switch (spec->src_type | spec->dst_type) {
 667         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 668             if (spec->dst.ofs == 0
 669                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 670                 union mf_value value;
 671
 672                 memset(&value, 0, sizeof value);
 673                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 674                              &value, spec->dst.field->n_bytes, 0,
 675                              spec->dst.field->n_bits);
 676                 ds_put_format(s, "%s=", spec->dst.field->name);
 677                 mf_format(spec->dst.field, &value, NULL, s);
 678             } else {
 679                 mf_format_subfield(&spec->dst, s);
 680                 ds_put_char(s, '=');
 681                 mf_format_subvalue(&spec->src_imm, s);
 682             }
 683             break;
 684
 685         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 686             mf_format_subfield(&spec->dst, s);
 687             if (spec->src.field != spec->dst.field ||
 688                 spec->src.ofs != spec->dst.ofs) {
 689                 ds_put_char(s, '=');
 690                 mf_format_subfield(&spec->src, s);
 691             }
 692             break;
 693
 694         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 695             ds_put_format(s, "load:");
 696             mf_format_subvalue(&spec->src_imm, s);
 697             ds_put_cstr(s, "->");
 698             mf_format_subfield(&spec->dst, s);
 699             break;
 700
 701         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 702             ds_put_cstr(s, "load:");
 703             mf_format_subfield(&spec->src, s);
 704             ds_put_cstr(s, "->");
 705             mf_format_subfield(&spec->dst, s);
 706             break;
 707
 708         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 709             ds_put_cstr(s, "output:");
 710             mf_format_subfield(&spec->src, s);
 711             break;
 712         }
 713     }
 714     ds_put_char(s, ')');
 715 }