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->buffer_id = UINT32_MAX;
 105     fm->out_port = OFPP_NONE;
 106     fm->flags = 0;
 107     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 108         fm->flags |= OFPUTIL_FF_SEND_FLOW_REM;
 109     }
 110     fm->ofpacts = NULL;
 111     fm->ofpacts_len = 0;
 112     fm->delete_reason = OFPRR_DELETE;
 113
 114     if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
 115         struct ofpact_fin_timeout *oft;
 116
 117         oft = ofpact_put_FIN_TIMEOUT(ofpacts);
 118         oft->fin_idle_timeout = learn->fin_idle_timeout;
 119         oft->fin_hard_timeout = learn->fin_hard_timeout;
 120     }
 121
 122     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 123         struct ofpact_set_field *sf;
 124         union mf_subvalue value;
 125
 126         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 127             mf_read_subfield(&spec->src, flow, &value);
 128         } else {
 129             value = spec->src_imm;
 130         }
 131
 132         switch (spec->dst_type) {
 133         case NX_LEARN_DST_MATCH:
 134             mf_write_subfield(&spec->dst, &value, &fm->match);
 135             break;
 136
 137         case NX_LEARN_DST_LOAD:
 138             sf = ofpact_put_reg_load(ofpacts);
 139             sf->field = spec->dst.field;
 140             bitwise_copy(&value, sizeof value, 0,
 141                          &sf->value, spec->dst.field->n_bytes, spec->dst.ofs,
 142                          spec->n_bits);
 143             bitwise_one(&sf->mask, spec->dst.field->n_bytes, spec->dst.ofs,
 144                         spec->n_bits);
 145             break;
 146
 147         case NX_LEARN_DST_OUTPUT:
 148             if (spec->n_bits <= 16
 149                 || is_all_zeros(value.u8, sizeof value - 2)) {
 150                 ofp_port_t port = u16_to_ofp(ntohs(value.be16[7]));
 151
 152                 if (ofp_to_u16(port) < ofp_to_u16(OFPP_MAX)
 153                     || port == OFPP_IN_PORT
 154                     || port == OFPP_FLOOD
 155                     || port == OFPP_LOCAL
 156                     || port == OFPP_ALL) {
 157                     ofpact_put_OUTPUT(ofpacts)->port = port;
 158                 }
 159             }
 160             break;
 161         }
 162     }
 163     ofpact_pad(ofpacts);
 164
 165     fm->ofpacts = ofpbuf_data(ofpacts);
 166     fm->ofpacts_len = ofpbuf_size(ofpacts);
 167 }
 168
 169 /* Perform a bitwise-OR on 'wc''s fields that are relevant as sources in
 170  * the learn action 'learn'. */
 171 void
 172 learn_mask(const struct ofpact_learn *learn, struct flow_wildcards *wc)
 173 {
 174     const struct ofpact_learn_spec *spec;
 175     union mf_subvalue value;
 176
 177     memset(&value, 0xff, sizeof value);
 178     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 179         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 180             mf_write_subfield_flow(&spec->src, &value, &wc->masks);
 181         }
 182     }
 183 }
 184
 185 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 186  * error.  The caller is responsible for freeing the returned string. */
 187 static char * WARN_UNUSED_RESULT
 188 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 189 {
 190     const char *full_s = s;
 191     const char *arrow = strstr(s, "->");
 192     struct mf_subfield dst;
 193     union mf_subvalue imm;
 194     char *error;
 195
 196     memset(&imm, 0, sizeof imm);
 197     if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X') && arrow) {
 198         const char *in = arrow - 1;
 199         uint8_t *out = imm.u8 + sizeof imm.u8 - 1;
 200         int n = arrow - (s + 2);
 201         int i;
 202
 203         for (i = 0; i < n; i++) {
 204             int hexit = hexit_value(in[-i]);
 205             if (hexit < 0) {
 206                 return xasprintf("%s: bad hex digit in value", full_s);
 207             }
 208             out[-(i / 2)] |= i % 2 ? hexit << 4 : hexit;
 209         }
 210         s = arrow;
 211     } else {
 212         imm.be64[1] = htonll(strtoull(s, (char **) &s, 0));
 213     }
 214
 215     if (strncmp(s, "->", 2)) {
 216         return xasprintf("%s: missing `->' following value", full_s);
 217     }
 218     s += 2;
 219
 220     error = mf_parse_subfield(&dst, s);
 221     if (error) {
 222         return error;
 223     }
 224     if (!mf_nxm_header(dst.field->id)) {
 225         return xasprintf("%s: experimenter OXM field '%s' not supported",
 226                          full_s, s);
 227     }
 228
 229     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 230                               (8 * sizeof imm) - dst.n_bits)) {
 231         return xasprintf("%s: value does not fit into %u bits",
 232                          full_s, dst.n_bits);
 233     }
 234
 235     spec->n_bits = dst.n_bits;
 236     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 237     spec->src_imm = imm;
 238     spec->dst_type = NX_LEARN_DST_LOAD;
 239     spec->dst = dst;
 240     return NULL;
 241 }
 242
 243 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 244  * error.  The caller is responsible for freeing the returned string. */
 245 static char * WARN_UNUSED_RESULT
 246 learn_parse_spec(const char *orig, char *name, char *value,
 247                  struct ofpact_learn_spec *spec)
 248 {
 249     if (mf_from_name(name)) {
 250         const struct mf_field *dst = mf_from_name(name);
 251         union mf_value imm;
 252         char *error;
 253
 254         error = mf_parse_value(dst, value, &imm);
 255         if (error) {
 256             return error;
 257         }
 258
 259         spec->n_bits = dst->n_bits;
 260         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 261         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 262         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 263                &imm, dst->n_bytes);
 264         spec->dst_type = NX_LEARN_DST_MATCH;
 265         spec->dst.field = dst;
 266         spec->dst.ofs = 0;
 267         spec->dst.n_bits = dst->n_bits;
 268     } else if (strchr(name, '[')) {
 269         /* Parse destination and check prerequisites. */
 270         char *error;
 271
 272         error = mf_parse_subfield(&spec->dst, name);
 273         if (error) {
 274             return error;
 275         }
 276         if (!mf_nxm_header(spec->dst.field->id)) {
 277             return xasprintf("%s: experimenter OXM field '%s' not supported",
 278                              orig, name);
 279         }
 280
 281         /* Parse source and check prerequisites. */
 282         if (value[0] != '\0') {
 283             error = mf_parse_subfield(&spec->src, value);
 284             if (error) {
 285                 return error;
 286             }
 287             if (spec->src.n_bits != spec->dst.n_bits) {
 288                 return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
 289                                  "differ", orig, name, spec->src.n_bits, value,
 290                                  spec->dst.n_bits);
 291             }
 292         } else {
 293             spec->src = spec->dst;
 294         }
 295
 296         spec->n_bits = spec->src.n_bits;
 297         spec->src_type = NX_LEARN_SRC_FIELD;
 298         spec->dst_type = NX_LEARN_DST_MATCH;
 299     } else if (!strcmp(name, "load")) {
 300         if (value[strcspn(value, "[-")] == '-') {
 301             char *error = learn_parse_load_immediate(value, spec);
 302             if (error) {
 303                 return error;
 304             }
 305         } else {
 306             struct ofpact_reg_move move;
 307             char *error;
 308
 309             error = nxm_parse_reg_move(&move, value);
 310             if (error) {
 311                 return error;
 312             }
 313
 314             spec->n_bits = move.src.n_bits;
 315             spec->src_type = NX_LEARN_SRC_FIELD;
 316             spec->src = move.src;
 317             spec->dst_type = NX_LEARN_DST_LOAD;
 318             spec->dst = move.dst;
 319         }
 320     } else if (!strcmp(name, "output")) {
 321         char *error = mf_parse_subfield(&spec->src, value);
 322         if (error) {
 323             return error;
 324         }
 325
 326         spec->n_bits = spec->src.n_bits;
 327         spec->src_type = NX_LEARN_SRC_FIELD;
 328         spec->dst_type = NX_LEARN_DST_OUTPUT;
 329     } else {
 330         return xasprintf("%s: unknown keyword %s", orig, name);
 331     }
 332
 333     return NULL;
 334 }
 335
 336 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 337  * error.  The caller is responsible for freeing the returned string. */
 338 static char * WARN_UNUSED_RESULT
 339 learn_parse__(char *orig, char *arg, struct ofpbuf *ofpacts)
 340 {
 341     struct ofpact_learn *learn;
 342     struct match match;
 343     char *name, *value;
 344
 345     learn = ofpact_put_LEARN(ofpacts);
 346     learn->idle_timeout = OFP_FLOW_PERMANENT;
 347     learn->hard_timeout = OFP_FLOW_PERMANENT;
 348     learn->priority = OFP_DEFAULT_PRIORITY;
 349     learn->table_id = 1;
 350
 351     match_init_catchall(&match);
 352     while (ofputil_parse_key_value(&arg, &name, &value)) {
 353         if (!strcmp(name, "table")) {
 354             learn->table_id = atoi(value);
 355             if (learn->table_id == 255) {
 356                 return xasprintf("%s: table id 255 not valid for `learn' "
 357                                  "action", orig);
 358             }
 359         } else if (!strcmp(name, "priority")) {
 360             learn->priority = atoi(value);
 361         } else if (!strcmp(name, "idle_timeout")) {
 362             learn->idle_timeout = atoi(value);
 363         } else if (!strcmp(name, "hard_timeout")) {
 364             learn->hard_timeout = atoi(value);
 365         } else if (!strcmp(name, "fin_idle_timeout")) {
 366             learn->fin_idle_timeout = atoi(value);
 367         } else if (!strcmp(name, "fin_hard_timeout")) {
 368             learn->fin_hard_timeout = atoi(value);
 369         } else if (!strcmp(name, "cookie")) {
 370             learn->cookie = htonll(strtoull(value, NULL, 0));
 371         } else if (!strcmp(name, "send_flow_rem")) {
 372             learn->flags |= NX_LEARN_F_SEND_FLOW_REM;
 373         } else if (!strcmp(name, "delete_learned")) {
 374             learn->flags |= NX_LEARN_F_DELETE_LEARNED;
 375         } else {
 376             struct ofpact_learn_spec *spec;
 377             char *error;
 378
 379             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 380             learn = ofpacts->frame;
 381             learn->n_specs++;
 382
 383             error = learn_parse_spec(orig, name, value, spec);
 384             if (error) {
 385                 return error;
 386             }
 387
 388             /* Update 'match' to allow for satisfying destination
 389              * prerequisites. */
 390             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 391                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 392                 mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 393             }
 394         }
 395     }
 396     ofpact_update_len(ofpacts, &learn->ofpact);
 397
 398     return NULL;
 399 }
 400
 401 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 402  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 403  * format parsed.
 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  *
 408  * If 'flow' is nonnull, then it should be the flow from a struct match that is
 409  * the matching rule for the learning action.  This helps to better validate
 410  * the action's arguments.
 411  *
 412  * Modifies 'arg'. */
 413 char * WARN_UNUSED_RESULT
 414 learn_parse(char *arg, struct ofpbuf *ofpacts)
 415 {
 416     char *orig = xstrdup(arg);
 417     char *error = learn_parse__(orig, arg, ofpacts);
 418     free(orig);
 419     return error;
 420 }
 421
 422 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 423  * describes. */
 424 void
 425 learn_format(const struct ofpact_learn *learn, struct ds *s)
 426 {
 427     const struct ofpact_learn_spec *spec;
 428     struct match match;
 429
 430     match_init_catchall(&match);
 431
 432     ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
 433     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 434         ds_put_format(s, ",idle_timeout=%"PRIu16, learn->idle_timeout);
 435     }
 436     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 437         ds_put_format(s, ",hard_timeout=%"PRIu16, learn->hard_timeout);
 438     }
 439     if (learn->fin_idle_timeout) {
 440         ds_put_format(s, ",fin_idle_timeout=%"PRIu16, learn->fin_idle_timeout);
 441     }
 442     if (learn->fin_hard_timeout) {
 443         ds_put_format(s, ",fin_hard_timeout=%"PRIu16, learn->fin_hard_timeout);
 444     }
 445     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 446         ds_put_format(s, ",priority=%"PRIu16, learn->priority);
 447     }
 448     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 449         ds_put_cstr(s, ",send_flow_rem");
 450     }
 451     if (learn->flags & NX_LEARN_F_DELETE_LEARNED) {
 452         ds_put_cstr(s, ",delete_learned");
 453     }
 454     if (learn->cookie != 0) {
 455         ds_put_format(s, ",cookie=%#"PRIx64, ntohll(learn->cookie));
 456     }
 457
 458     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 459         ds_put_char(s, ',');
 460
 461         switch (spec->src_type | spec->dst_type) {
 462         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 463             if (spec->dst.ofs == 0
 464                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 465                 union mf_value value;
 466
 467                 memset(&value, 0, sizeof value);
 468                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 469                              &value, spec->dst.field->n_bytes, 0,
 470                              spec->dst.field->n_bits);
 471                 ds_put_format(s, "%s=", spec->dst.field->name);
 472                 mf_format(spec->dst.field, &value, NULL, s);
 473             } else {
 474                 mf_format_subfield(&spec->dst, s);
 475                 ds_put_char(s, '=');
 476                 mf_format_subvalue(&spec->src_imm, s);
 477             }
 478             break;
 479
 480         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 481             mf_format_subfield(&spec->dst, s);
 482             if (spec->src.field != spec->dst.field ||
 483                 spec->src.ofs != spec->dst.ofs) {
 484                 ds_put_char(s, '=');
 485                 mf_format_subfield(&spec->src, s);
 486             }
 487             break;
 488
 489         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 490             ds_put_format(s, "load:");
 491             mf_format_subvalue(&spec->src_imm, s);
 492             ds_put_cstr(s, "->");
 493             mf_format_subfield(&spec->dst, s);
 494             break;
 495
 496         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 497             ds_put_cstr(s, "load:");
 498             mf_format_subfield(&spec->src, s);
 499             ds_put_cstr(s, "->");
 500             mf_format_subfield(&spec->dst, s);
 501             break;
 502
 503         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 504             ds_put_cstr(s, "output:");
 505             mf_format_subfield(&spec->src, s);
 506             break;
 507         }
 508     }
 509     ds_put_char(s, ')');
 510 }