lib/learn.c

   1 /*
   2  * Copyright (c) 2011, 2012, 2013, 2014 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
  34 /* Checks that 'learn' is a valid action on 'flow'.  Returns 0 if it is valid,
  35  * otherwise an OFPERR_*. */
  36 enum ofperr
  37 learn_check(const struct ofpact_learn *learn, const struct flow *flow)
  38 {
  39     const struct ofpact_learn_spec *spec;
  40     struct match match;
  41
  42     match_init_catchall(&match);
  43     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
  44         enum ofperr error;
  45
  46         /* Check the source. */
  47         if (spec->src_type == NX_LEARN_SRC_FIELD) {
  48             error = mf_check_src(&spec->src, flow);
  49             if (error) {
  50                 return error;
  51             }
  52         }
  53
  54         /* Check the destination. */
  55         switch (spec->dst_type) {
  56         case NX_LEARN_DST_MATCH:
  57             error = mf_check_src(&spec->dst, &match.flow);
  58             if (error) {
  59                 return error;
  60             }
  61
  62             mf_write_subfield(&spec->dst, &spec->src_imm, &match);
  63             break;
  64
  65         case NX_LEARN_DST_LOAD:
  66             error = mf_check_dst(&spec->dst, &match.flow);
  67             if (error) {
  68                 return error;
  69             }
  70             break;
  71
  72         case NX_LEARN_DST_OUTPUT:
  73             /* Nothing to do. */
  74             break;
  75         }
  76     }
  77     return 0;
  78 }
  79
  80 /* Composes 'fm' so that executing it will implement 'learn' given that the
  81  * packet being processed has 'flow' as its flow.
  82  *
  83  * Uses 'ofpacts' to store the flow mod's actions.  The caller must initialize
  84  * 'ofpacts' and retains ownership of it.  'fm->ofpacts' will point into the
  85  * 'ofpacts' buffer.
  86  *
  87  * The caller has to actually execute 'fm'. */
  88 void
  89 learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
  90               struct ofputil_flow_mod *fm, struct ofpbuf *ofpacts)
  91 {
  92     const struct ofpact_learn_spec *spec;
  93
  94     match_init_catchall(&fm->match);
  95     fm->priority = learn->priority;
  96     fm->cookie = htonll(0);
  97     fm->cookie_mask = htonll(0);
  98     fm->new_cookie = learn->cookie;
  99     fm->modify_cookie = fm->new_cookie != OVS_BE64_MAX;
 100     fm->table_id = learn->table_id;
 101     fm->command = OFPFC_MODIFY_STRICT;
 102     fm->idle_timeout = learn->idle_timeout;
 103     fm->hard_timeout = learn->hard_timeout;
 104     fm->importance = 0;
 105     fm->buffer_id = UINT32_MAX;
 106     fm->out_port = OFPP_NONE;
 107     fm->flags = 0;
 108     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 109         fm->flags |= OFPUTIL_FF_SEND_FLOW_REM;
 110     }
 111     fm->ofpacts = NULL;
 112     fm->ofpacts_len = 0;
 113     fm->delete_reason = OFPRR_DELETE;
 114
 115     if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
 116         struct ofpact_fin_timeout *oft;
 117
 118         oft = ofpact_put_FIN_TIMEOUT(ofpacts);
 119         oft->fin_idle_timeout = learn->fin_idle_timeout;
 120         oft->fin_hard_timeout = learn->fin_hard_timeout;
 121     }
 122
 123     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 124         struct ofpact_set_field *sf;
 125         union mf_subvalue value;
 126
 127         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 128             mf_read_subfield(&spec->src, flow, &value);
 129         } else {
 130             value = spec->src_imm;
 131         }
 132
 133         switch (spec->dst_type) {
 134         case NX_LEARN_DST_MATCH:
 135             mf_write_subfield(&spec->dst, &value, &fm->match);
 136             break;
 137
 138         case NX_LEARN_DST_LOAD:
 139             sf = ofpact_put_reg_load(ofpacts);
 140             sf->field = spec->dst.field;
 141             bitwise_copy(&value, sizeof value, 0,
 142                          &sf->value, spec->dst.field->n_bytes, spec->dst.ofs,
 143                          spec->n_bits);
 144             bitwise_one(&sf->mask, spec->dst.field->n_bytes, spec->dst.ofs,
 145                         spec->n_bits);
 146             break;
 147
 148         case NX_LEARN_DST_OUTPUT:
 149             if (spec->n_bits <= 16
 150                 || is_all_zeros(value.u8, sizeof value - 2)) {
 151                 ovs_be16 *last_be16 = &value.be16[ARRAY_SIZE(value.be16) - 1];
 152                 ofp_port_t port = u16_to_ofp(ntohs(*last_be16));
 153
 154                 if (ofp_to_u16(port) < ofp_to_u16(OFPP_MAX)
 155                     || port == OFPP_IN_PORT
 156                     || port == OFPP_FLOOD
 157                     || port == OFPP_LOCAL
 158                     || port == OFPP_ALL) {
 159                     ofpact_put_OUTPUT(ofpacts)->port = port;
 160                 }
 161             }
 162             break;
 163         }
 164     }
 165     ofpact_pad(ofpacts);
 166
 167     fm->ofpacts = ofpacts->data;
 168     fm->ofpacts_len = ofpacts->size;
 169 }
 170
 171 /* Perform a bitwise-OR on 'wc''s fields that are relevant as sources in
 172  * the learn action 'learn'. */
 173 void
 174 learn_mask(const struct ofpact_learn *learn, struct flow_wildcards *wc)
 175 {
 176     const struct ofpact_learn_spec *spec;
 177     union mf_subvalue value;
 178
 179     memset(&value, 0xff, sizeof value);
 180     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 181         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 182             mf_write_subfield_flow(&spec->src, &value, &wc->masks);
 183         }
 184     }
 185 }
 186
 187 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 188  * error.  The caller is responsible for freeing the returned string. */
 189 static char * OVS_WARN_UNUSED_RESULT
 190 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 191 {
 192     const char *full_s = s;
 193     struct mf_subfield dst;
 194     union mf_subvalue imm;
 195     char *error;
 196     int err;
 197
 198     err = parse_int_string(s, imm.u8, sizeof imm.u8, (char **) &s);
 199     if (err) {
 200         return xasprintf("%s: bad hex digit in value", full_s);
 201     }
 202
 203     if (strncmp(s, "->", 2)) {
 204         return xasprintf("%s: missing `->' following value", full_s);
 205     }
 206     s += 2;
 207
 208     error = mf_parse_subfield(&dst, s);
 209     if (error) {
 210         return error;
 211     }
 212     if (!mf_nxm_header(dst.field->id)) {
 213         return xasprintf("%s: experimenter OXM field '%s' not supported",
 214                          full_s, s);
 215     }
 216
 217     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 218                               (8 * sizeof imm) - dst.n_bits)) {
 219         return xasprintf("%s: value does not fit into %u bits",
 220                          full_s, dst.n_bits);
 221     }
 222
 223     spec->n_bits = dst.n_bits;
 224     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 225     spec->src_imm = imm;
 226     spec->dst_type = NX_LEARN_DST_LOAD;
 227     spec->dst = dst;
 228     return NULL;
 229 }
 230
 231 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 232  * error.  The caller is responsible for freeing the returned string. */
 233 static char * OVS_WARN_UNUSED_RESULT
 234 learn_parse_spec(const char *orig, char *name, char *value,
 235                  struct ofpact_learn_spec *spec)
 236 {
 237     if (mf_from_name(name)) {
 238         const struct mf_field *dst = mf_from_name(name);
 239         union mf_value imm;
 240         char *error;
 241
 242         error = mf_parse_value(dst, value, &imm);
 243         if (error) {
 244             return error;
 245         }
 246
 247         spec->n_bits = dst->n_bits;
 248         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 249         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 250         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 251                &imm, dst->n_bytes);
 252         spec->dst_type = NX_LEARN_DST_MATCH;
 253         spec->dst.field = dst;
 254         spec->dst.ofs = 0;
 255         spec->dst.n_bits = dst->n_bits;
 256     } else if (strchr(name, '[')) {
 257         /* Parse destination and check prerequisites. */
 258         char *error;
 259
 260         error = mf_parse_subfield(&spec->dst, name);
 261         if (error) {
 262             return error;
 263         }
 264         if (!mf_nxm_header(spec->dst.field->id)) {
 265             return xasprintf("%s: experimenter OXM field '%s' not supported",
 266                              orig, name);
 267         }
 268
 269         /* Parse source and check prerequisites. */
 270         if (value[0] != '\0') {
 271             error = mf_parse_subfield(&spec->src, value);
 272             if (error) {
 273                 return error;
 274             }
 275             if (spec->src.n_bits != spec->dst.n_bits) {
 276                 return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
 277                                  "differ", orig, name, spec->src.n_bits, value,
 278                                  spec->dst.n_bits);
 279             }
 280         } else {
 281             spec->src = spec->dst;
 282         }
 283
 284         spec->n_bits = spec->src.n_bits;
 285         spec->src_type = NX_LEARN_SRC_FIELD;
 286         spec->dst_type = NX_LEARN_DST_MATCH;
 287     } else if (!strcmp(name, "load")) {
 288         if (value[strcspn(value, "[-")] == '-') {
 289             char *error = learn_parse_load_immediate(value, spec);
 290             if (error) {
 291                 return error;
 292             }
 293         } else {
 294             struct ofpact_reg_move move;
 295             char *error;
 296
 297             error = nxm_parse_reg_move(&move, value);
 298             if (error) {
 299                 return error;
 300             }
 301
 302             spec->n_bits = move.src.n_bits;
 303             spec->src_type = NX_LEARN_SRC_FIELD;
 304             spec->src = move.src;
 305             spec->dst_type = NX_LEARN_DST_LOAD;
 306             spec->dst = move.dst;
 307         }
 308     } else if (!strcmp(name, "output")) {
 309         char *error = mf_parse_subfield(&spec->src, value);
 310         if (error) {
 311             return error;
 312         }
 313
 314         spec->n_bits = spec->src.n_bits;
 315         spec->src_type = NX_LEARN_SRC_FIELD;
 316         spec->dst_type = NX_LEARN_DST_OUTPUT;
 317     } else {
 318         return xasprintf("%s: unknown keyword %s", orig, name);
 319     }
 320
 321     return NULL;
 322 }
 323
 324 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 325  * error.  The caller is responsible for freeing the returned string. */
 326 static char * OVS_WARN_UNUSED_RESULT
 327 learn_parse__(char *orig, char *arg, struct ofpbuf *ofpacts)
 328 {
 329     struct ofpact_learn *learn;
 330     struct match match;
 331     char *name, *value;
 332
 333     learn = ofpact_put_LEARN(ofpacts);
 334     learn->idle_timeout = OFP_FLOW_PERMANENT;
 335     learn->hard_timeout = OFP_FLOW_PERMANENT;
 336     learn->priority = OFP_DEFAULT_PRIORITY;
 337     learn->table_id = 1;
 338
 339     match_init_catchall(&match);
 340     while (ofputil_parse_key_value(&arg, &name, &value)) {
 341         if (!strcmp(name, "table")) {
 342             learn->table_id = atoi(value);
 343             if (learn->table_id == 255) {
 344                 return xasprintf("%s: table id 255 not valid for `learn' "
 345                                  "action", orig);
 346             }
 347         } else if (!strcmp(name, "priority")) {
 348             learn->priority = atoi(value);
 349         } else if (!strcmp(name, "idle_timeout")) {
 350             learn->idle_timeout = atoi(value);
 351         } else if (!strcmp(name, "hard_timeout")) {
 352             learn->hard_timeout = atoi(value);
 353         } else if (!strcmp(name, "fin_idle_timeout")) {
 354             learn->fin_idle_timeout = atoi(value);
 355         } else if (!strcmp(name, "fin_hard_timeout")) {
 356             learn->fin_hard_timeout = atoi(value);
 357         } else if (!strcmp(name, "cookie")) {
 358             learn->cookie = htonll(strtoull(value, NULL, 0));
 359         } else if (!strcmp(name, "send_flow_rem")) {
 360             learn->flags |= NX_LEARN_F_SEND_FLOW_REM;
 361         } else if (!strcmp(name, "delete_learned")) {
 362             learn->flags |= NX_LEARN_F_DELETE_LEARNED;
 363         } else {
 364             struct ofpact_learn_spec *spec;
 365             char *error;
 366
 367             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 368             learn = ofpacts->header;
 369             learn->n_specs++;
 370
 371             error = learn_parse_spec(orig, name, value, spec);
 372             if (error) {
 373                 return error;
 374             }
 375
 376             /* Update 'match' to allow for satisfying destination
 377              * prerequisites. */
 378             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 379                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 380                 mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 381             }
 382         }
 383     }
 384     ofpact_update_len(ofpacts, &learn->ofpact);
 385
 386     return NULL;
 387 }
 388
 389 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 390  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 391  * format parsed.
 392  *
 393  * Returns NULL if successful, otherwise a malloc()'d string describing the
 394  * error.  The caller is responsible for freeing the returned string.
 395  *
 396  * If 'flow' is nonnull, then it should be the flow from a struct match that is
 397  * the matching rule for the learning action.  This helps to better validate
 398  * the action's arguments.
 399  *
 400  * Modifies 'arg'. */
 401 char * OVS_WARN_UNUSED_RESULT
 402 learn_parse(char *arg, struct ofpbuf *ofpacts)
 403 {
 404     char *orig = xstrdup(arg);
 405     char *error = learn_parse__(orig, arg, ofpacts);
 406     free(orig);
 407     return error;
 408 }
 409
 410 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 411  * describes. */
 412 void
 413 learn_format(const struct ofpact_learn *learn, struct ds *s)
 414 {
 415     const struct ofpact_learn_spec *spec;
 416     struct match match;
 417
 418     match_init_catchall(&match);
 419
 420     ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
 421     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 422         ds_put_format(s, ",idle_timeout=%"PRIu16, learn->idle_timeout);
 423     }
 424     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 425         ds_put_format(s, ",hard_timeout=%"PRIu16, learn->hard_timeout);
 426     }
 427     if (learn->fin_idle_timeout) {
 428         ds_put_format(s, ",fin_idle_timeout=%"PRIu16, learn->fin_idle_timeout);
 429     }
 430     if (learn->fin_hard_timeout) {
 431         ds_put_format(s, ",fin_hard_timeout=%"PRIu16, learn->fin_hard_timeout);
 432     }
 433     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 434         ds_put_format(s, ",priority=%"PRIu16, learn->priority);
 435     }
 436     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 437         ds_put_cstr(s, ",send_flow_rem");
 438     }
 439     if (learn->flags & NX_LEARN_F_DELETE_LEARNED) {
 440         ds_put_cstr(s, ",delete_learned");
 441     }
 442     if (learn->cookie != 0) {
 443         ds_put_format(s, ",cookie=%#"PRIx64, ntohll(learn->cookie));
 444     }
 445
 446     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 447         ds_put_char(s, ',');
 448
 449         switch (spec->src_type | spec->dst_type) {
 450         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 451             if (spec->dst.ofs == 0
 452                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 453                 union mf_value value;
 454
 455                 memset(&value, 0, sizeof value);
 456                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 457                              &value, spec->dst.field->n_bytes, 0,
 458                              spec->dst.field->n_bits);
 459                 ds_put_format(s, "%s=", spec->dst.field->name);
 460                 mf_format(spec->dst.field, &value, NULL, s);
 461             } else {
 462                 mf_format_subfield(&spec->dst, s);
 463                 ds_put_char(s, '=');
 464                 mf_format_subvalue(&spec->src_imm, s);
 465             }
 466             break;
 467
 468         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 469             mf_format_subfield(&spec->dst, s);
 470             if (spec->src.field != spec->dst.field ||
 471                 spec->src.ofs != spec->dst.ofs) {
 472                 ds_put_char(s, '=');
 473                 mf_format_subfield(&spec->src, s);
 474             }
 475             break;
 476
 477         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 478             ds_put_format(s, "load:");
 479             mf_format_subvalue(&spec->src_imm, s);
 480             ds_put_cstr(s, "->");
 481             mf_format_subfield(&spec->dst, s);
 482             break;
 483
 484         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 485             ds_put_cstr(s, "load:");
 486             mf_format_subfield(&spec->src, s);
 487             ds_put_cstr(s, "->");
 488             mf_format_subfield(&spec->dst, s);
 489             break;
 490
 491         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 492             ds_put_cstr(s, "output:");
 493             mf_format_subfield(&spec->src, s);
 494             break;
 495         }
 496     }
 497     ds_put_char(s, ')');
 498 }