lib/learn.c

   1 /*
   2  * Copyright (c) 2011, 2012, 2013, 2014, 2015, 2016 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 "colors.h"
  23 #include "openvswitch/dynamic-string.h"
  24 #include "match.h"
  25 #include "meta-flow.h"
  26 #include "nx-match.h"
  27 #include "ofp-actions.h"
  28 #include "ofp-util.h"
  29 #include "ofpbuf.h"
  30 #include "openflow/openflow.h"
  31 #include "openvswitch/ofp-errors.h"
  32 #include "unaligned.h"
  33
  34
  35 /* Checks that 'learn' is a valid action on 'flow'.  Returns 0 if it is valid,
  36  * otherwise an OFPERR_*. */
  37 enum ofperr
  38 learn_check(const struct ofpact_learn *learn, const struct flow *flow)
  39 {
  40     const struct ofpact_learn_spec *spec;
  41     struct match match;
  42
  43     match_init_catchall(&match);
  44     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
  45         enum ofperr error;
  46
  47         /* Check the source. */
  48         if (spec->src_type == NX_LEARN_SRC_FIELD) {
  49             error = mf_check_src(&spec->src, flow);
  50             if (error) {
  51                 return error;
  52             }
  53         }
  54
  55         /* Check the destination. */
  56         switch (spec->dst_type) {
  57         case NX_LEARN_DST_MATCH:
  58             error = mf_check_src(&spec->dst, &match.flow);
  59             if (error) {
  60                 return error;
  61             }
  62
  63             mf_write_subfield(&spec->dst, &spec->src_imm, &match);
  64             break;
  65
  66         case NX_LEARN_DST_LOAD:
  67             error = mf_check_dst(&spec->dst, &match.flow);
  68             if (error) {
  69                 return error;
  70             }
  71             break;
  72
  73         case NX_LEARN_DST_OUTPUT:
  74             /* Nothing to do. */
  75             break;
  76         }
  77     }
  78     return 0;
  79 }
  80
  81 /* Composes 'fm' so that executing it will implement 'learn' given that the
  82  * packet being processed has 'flow' as its flow.
  83  *
  84  * Uses 'ofpacts' to store the flow mod's actions.  The caller must initialize
  85  * 'ofpacts' and retains ownership of it.  'fm->ofpacts' will point into the
  86  * 'ofpacts' buffer.
  87  *
  88  * The caller has to actually execute 'fm'. */
  89 void
  90 learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
  91               struct ofputil_flow_mod *fm, struct ofpbuf *ofpacts)
  92 {
  93     const struct ofpact_learn_spec *spec;
  94
  95     match_init_catchall(&fm->match);
  96     fm->priority = learn->priority;
  97     fm->cookie = htonll(0);
  98     fm->cookie_mask = htonll(0);
  99     fm->new_cookie = learn->cookie;
 100     fm->modify_cookie = fm->new_cookie != OVS_BE64_MAX;
 101     fm->table_id = learn->table_id;
 102     fm->command = OFPFC_MODIFY_STRICT;
 103     fm->idle_timeout = learn->idle_timeout;
 104     fm->hard_timeout = learn->hard_timeout;
 105     fm->importance = 0;
 106     fm->buffer_id = UINT32_MAX;
 107     fm->out_port = OFPP_NONE;
 108     fm->flags = 0;
 109     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 110         fm->flags |= OFPUTIL_FF_SEND_FLOW_REM;
 111     }
 112     fm->ofpacts = NULL;
 113     fm->ofpacts_len = 0;
 114     fm->delete_reason = OFPRR_DELETE;
 115
 116     if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
 117         struct ofpact_fin_timeout *oft;
 118
 119         oft = ofpact_put_FIN_TIMEOUT(ofpacts);
 120         oft->fin_idle_timeout = learn->fin_idle_timeout;
 121         oft->fin_hard_timeout = learn->fin_hard_timeout;
 122     }
 123
 124     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 125         struct ofpact_set_field *sf;
 126         union mf_subvalue value;
 127
 128         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 129             mf_read_subfield(&spec->src, flow, &value);
 130         } else {
 131             value = spec->src_imm;
 132         }
 133
 134         switch (spec->dst_type) {
 135         case NX_LEARN_DST_MATCH:
 136             mf_write_subfield(&spec->dst, &value, &fm->match);
 137             break;
 138
 139         case NX_LEARN_DST_LOAD:
 140             sf = ofpact_put_reg_load(ofpacts);
 141             sf->field = spec->dst.field;
 142             bitwise_copy(&value, sizeof value, 0,
 143                          &sf->value, spec->dst.field->n_bytes, spec->dst.ofs,
 144                          spec->n_bits);
 145             bitwise_one(&sf->mask, spec->dst.field->n_bytes, spec->dst.ofs,
 146                         spec->n_bits);
 147             break;
 148
 149         case NX_LEARN_DST_OUTPUT:
 150             if (spec->n_bits <= 16
 151                 || is_all_zeros(value.u8, sizeof value - 2)) {
 152                 ofp_port_t port = u16_to_ofp(ntohll(value.integer));
 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
 166     fm->ofpacts = ofpacts->data;
 167     fm->ofpacts_len = ofpacts->size;
 168 }
 169
 170 /* Perform a bitwise-OR on 'wc''s fields that are relevant as sources in
 171  * the learn action 'learn'. */
 172 void
 173 learn_mask(const struct ofpact_learn *learn, struct flow_wildcards *wc)
 174 {
 175     const struct ofpact_learn_spec *spec;
 176     union mf_subvalue value;
 177
 178     memset(&value, 0xff, sizeof value);
 179     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 180         if (spec->src_type == NX_LEARN_SRC_FIELD) {
 181             mf_write_subfield_flow(&spec->src, &value, &wc->masks);
 182         }
 183     }
 184 }
 185
 186 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 187  * error.  The caller is responsible for freeing the returned string. */
 188 static char * OVS_WARN_UNUSED_RESULT
 189 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 190 {
 191     const char *full_s = s;
 192     struct mf_subfield dst;
 193     union mf_subvalue imm;
 194     char *error;
 195     int err;
 196
 197     err = parse_int_string(s, imm.u8, sizeof imm.u8, (char **) &s);
 198     if (err) {
 199         return xasprintf("%s: too many bits in immediate value", full_s);
 200     }
 201
 202     if (strncmp(s, "->", 2)) {
 203         return xasprintf("%s: missing `->' following value", full_s);
 204     }
 205     s += 2;
 206
 207     error = mf_parse_subfield(&dst, s);
 208     if (error) {
 209         return error;
 210     }
 211     if (!mf_nxm_header(dst.field->id)) {
 212         return xasprintf("%s: experimenter OXM field '%s' not supported",
 213                          full_s, s);
 214     }
 215
 216     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 217                               (8 * sizeof imm) - dst.n_bits)) {
 218         return xasprintf("%s: value does not fit into %u bits",
 219                          full_s, dst.n_bits);
 220     }
 221
 222     spec->n_bits = dst.n_bits;
 223     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 224     spec->src_imm = imm;
 225     spec->dst_type = NX_LEARN_DST_LOAD;
 226     spec->dst = dst;
 227     return NULL;
 228 }
 229
 230 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 231  * error.  The caller is responsible for freeing the returned string. */
 232 static char * OVS_WARN_UNUSED_RESULT
 233 learn_parse_spec(const char *orig, char *name, char *value,
 234                  struct ofpact_learn_spec *spec)
 235 {
 236     if (mf_from_name(name)) {
 237         const struct mf_field *dst = mf_from_name(name);
 238         union mf_value imm;
 239         char *error;
 240
 241         error = mf_parse_value(dst, value, &imm);
 242         if (error) {
 243             return error;
 244         }
 245
 246         spec->n_bits = dst->n_bits;
 247         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 248         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 249         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 250                &imm, dst->n_bytes);
 251         spec->dst_type = NX_LEARN_DST_MATCH;
 252         spec->dst.field = dst;
 253         spec->dst.ofs = 0;
 254         spec->dst.n_bits = dst->n_bits;
 255     } else if (strchr(name, '[')) {
 256         /* Parse destination and check prerequisites. */
 257         char *error;
 258
 259         error = mf_parse_subfield(&spec->dst, name);
 260         if (error) {
 261             return error;
 262         }
 263         if (!mf_nxm_header(spec->dst.field->id)) {
 264             return xasprintf("%s: experimenter OXM field '%s' not supported",
 265                              orig, name);
 266         }
 267
 268         /* Parse source and check prerequisites. */
 269         if (value[0] != '\0') {
 270             error = mf_parse_subfield(&spec->src, value);
 271             if (error) {
 272                 return error;
 273             }
 274             if (spec->src.n_bits != spec->dst.n_bits) {
 275                 return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
 276                                  "differ", orig, name, spec->src.n_bits, value,
 277                                  spec->dst.n_bits);
 278             }
 279         } else {
 280             spec->src = spec->dst;
 281         }
 282
 283         spec->n_bits = spec->src.n_bits;
 284         spec->src_type = NX_LEARN_SRC_FIELD;
 285         spec->dst_type = NX_LEARN_DST_MATCH;
 286     } else if (!strcmp(name, "load")) {
 287         if (value[strcspn(value, "[-")] == '-') {
 288             char *error = learn_parse_load_immediate(value, spec);
 289             if (error) {
 290                 return error;
 291             }
 292         } else {
 293             struct ofpact_reg_move move;
 294             char *error;
 295
 296             error = nxm_parse_reg_move(&move, value);
 297             if (error) {
 298                 return error;
 299             }
 300
 301             spec->n_bits = move.src.n_bits;
 302             spec->src_type = NX_LEARN_SRC_FIELD;
 303             spec->src = move.src;
 304             spec->dst_type = NX_LEARN_DST_LOAD;
 305             spec->dst = move.dst;
 306         }
 307     } else if (!strcmp(name, "output")) {
 308         char *error = mf_parse_subfield(&spec->src, value);
 309         if (error) {
 310             return error;
 311         }
 312
 313         spec->n_bits = spec->src.n_bits;
 314         spec->src_type = NX_LEARN_SRC_FIELD;
 315         spec->dst_type = NX_LEARN_DST_OUTPUT;
 316     } else {
 317         return xasprintf("%s: unknown keyword %s", orig, name);
 318     }
 319
 320     return NULL;
 321 }
 322
 323 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 324  * error.  The caller is responsible for freeing the returned string. */
 325 static char * OVS_WARN_UNUSED_RESULT
 326 learn_parse__(char *orig, char *arg, struct ofpbuf *ofpacts)
 327 {
 328     struct ofpact_learn *learn;
 329     struct match match;
 330     char *name, *value;
 331
 332     learn = ofpact_put_LEARN(ofpacts);
 333     learn->idle_timeout = OFP_FLOW_PERMANENT;
 334     learn->hard_timeout = OFP_FLOW_PERMANENT;
 335     learn->priority = OFP_DEFAULT_PRIORITY;
 336     learn->table_id = 1;
 337
 338     match_init_catchall(&match);
 339     while (ofputil_parse_key_value(&arg, &name, &value)) {
 340         if (!strcmp(name, "table")) {
 341             learn->table_id = atoi(value);
 342             if (learn->table_id == 255) {
 343                 return xasprintf("%s: table id 255 not valid for `learn' "
 344                                  "action", orig);
 345             }
 346         } else if (!strcmp(name, "priority")) {
 347             learn->priority = atoi(value);
 348         } else if (!strcmp(name, "idle_timeout")) {
 349             learn->idle_timeout = atoi(value);
 350         } else if (!strcmp(name, "hard_timeout")) {
 351             learn->hard_timeout = atoi(value);
 352         } else if (!strcmp(name, "fin_idle_timeout")) {
 353             learn->fin_idle_timeout = atoi(value);
 354         } else if (!strcmp(name, "fin_hard_timeout")) {
 355             learn->fin_hard_timeout = atoi(value);
 356         } else if (!strcmp(name, "cookie")) {
 357             learn->cookie = htonll(strtoull(value, NULL, 0));
 358         } else if (!strcmp(name, "send_flow_rem")) {
 359             learn->flags |= NX_LEARN_F_SEND_FLOW_REM;
 360         } else if (!strcmp(name, "delete_learned")) {
 361             learn->flags |= NX_LEARN_F_DELETE_LEARNED;
 362         } else {
 363             struct ofpact_learn_spec *spec;
 364             char *error;
 365
 366             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 367             learn = ofpacts->header;
 368             learn->n_specs++;
 369
 370             error = learn_parse_spec(orig, name, value, spec);
 371             if (error) {
 372                 return error;
 373             }
 374
 375             /* Update 'match' to allow for satisfying destination
 376              * prerequisites. */
 377             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 378                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 379                 mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 380             }
 381         }
 382     }
 383     ofpact_finish(ofpacts, &learn->ofpact);
 384
 385     return NULL;
 386 }
 387
 388 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 389  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 390  * format parsed.
 391  *
 392  * Returns NULL if successful, otherwise a malloc()'d string describing the
 393  * error.  The caller is responsible for freeing the returned string.
 394  *
 395  * If 'flow' is nonnull, then it should be the flow from a struct match that is
 396  * the matching rule for the learning action.  This helps to better validate
 397  * the action's arguments.
 398  *
 399  * Modifies 'arg'. */
 400 char * OVS_WARN_UNUSED_RESULT
 401 learn_parse(char *arg, struct ofpbuf *ofpacts)
 402 {
 403     char *orig = xstrdup(arg);
 404     char *error = learn_parse__(orig, arg, ofpacts);
 405     free(orig);
 406     return error;
 407 }
 408
 409 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 410  * describes. */
 411 void
 412 learn_format(const struct ofpact_learn *learn, struct ds *s)
 413 {
 414     const struct ofpact_learn_spec *spec;
 415     struct match match;
 416
 417     match_init_catchall(&match);
 418
 419     ds_put_format(s, "%slearn(%s%stable=%s%"PRIu8,
 420                   colors.learn, colors.end, colors.special, colors.end,
 421                   learn->table_id);
 422     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 423         ds_put_format(s, ",%sidle_timeout=%s%"PRIu16,
 424                       colors.param, colors.end, learn->idle_timeout);
 425     }
 426     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 427         ds_put_format(s, ",%shard_timeout=%s%"PRIu16,
 428                       colors.param, colors.end, learn->hard_timeout);
 429     }
 430     if (learn->fin_idle_timeout) {
 431         ds_put_format(s, ",%sfin_idle_timeout=%s%"PRIu16,
 432                       colors.param, colors.end, learn->fin_idle_timeout);
 433     }
 434     if (learn->fin_hard_timeout) {
 435         ds_put_format(s, "%s,fin_hard_timeout=%s%"PRIu16,
 436                       colors.param, colors.end, learn->fin_hard_timeout);
 437     }
 438     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 439         ds_put_format(s, "%s,priority=%s%"PRIu16,
 440                       colors.special, colors.end, learn->priority);
 441     }
 442     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 443         ds_put_format(s, ",%ssend_flow_rem%s", colors.value, colors.end);
 444     }
 445     if (learn->flags & NX_LEARN_F_DELETE_LEARNED) {
 446         ds_put_format(s, ",%sdelete_learned%s", colors.value, colors.end);
 447     }
 448     if (learn->cookie != 0) {
 449         ds_put_format(s, ",%scookie=%s%#"PRIx64,
 450                       colors.param, colors.end, ntohll(learn->cookie));
 451     }
 452
 453     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 454         ds_put_char(s, ',');
 455
 456         switch (spec->src_type | spec->dst_type) {
 457         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 458             if (spec->dst.ofs == 0
 459                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 460                 union mf_value value;
 461
 462                 memset(&value, 0, sizeof value);
 463                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 464                              &value, spec->dst.field->n_bytes, 0,
 465                              spec->dst.field->n_bits);
 466                 ds_put_format(s, "%s%s=%s", colors.param,
 467                               spec->dst.field->name, colors.end);
 468                 mf_format(spec->dst.field, &value, NULL, s);
 469             } else {
 470                 ds_put_format(s, "%s", colors.param);
 471                 mf_format_subfield(&spec->dst, s);
 472                 ds_put_format(s, "=%s", colors.end);
 473                 mf_format_subvalue(&spec->src_imm, s);
 474             }
 475             break;
 476
 477         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 478             ds_put_format(s, "%s", colors.param);
 479             mf_format_subfield(&spec->dst, s);
 480             ds_put_format(s, "%s", colors.end);
 481             if (spec->src.field != spec->dst.field ||
 482                 spec->src.ofs != spec->dst.ofs) {
 483                 ds_put_format(s, "%s=%s", colors.param, colors.end);
 484                 mf_format_subfield(&spec->src, s);
 485             }
 486             break;
 487
 488         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 489             ds_put_format(s, "%sload:%s", colors.special, colors.end);
 490             mf_format_subvalue(&spec->src_imm, s);
 491             ds_put_format(s, "%s->%s", colors.special, colors.end);
 492             mf_format_subfield(&spec->dst, s);
 493             break;
 494
 495         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 496             ds_put_format(s, "%sload:%s", colors.special, colors.end);
 497             mf_format_subfield(&spec->src, s);
 498             ds_put_format(s, "%s->%s", colors.special, colors.end);
 499             mf_format_subfield(&spec->dst, s);
 500             break;
 501
 502         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 503             ds_put_format(s, "%soutput:%s", colors.special, colors.end);
 504             mf_format_subfield(&spec->src, s);
 505             break;
 506         }
 507     }
 508     ds_put_format(s, "%s)%s", colors.learn, colors.end);
 509 }