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 = ofpbuf_data(ofpacts);
 168     fm->ofpacts_len = ofpbuf_size(ofpacts);
 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 * WARN_UNUSED_RESULT
 190 learn_parse_load_immediate(const char *s, struct ofpact_learn_spec *spec)
 191 {
 192     const char *full_s = s;
 193     const char *arrow = strstr(s, "->");
 194     struct mf_subfield dst;
 195     union mf_subvalue imm;
 196     char *error;
 197
 198     memset(&imm, 0, sizeof imm);
 199     if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X') && arrow) {
 200         const char *in = arrow - 1;
 201         uint8_t *out = imm.u8 + sizeof imm.u8 - 1;
 202         int n = arrow - (s + 2);
 203         int i;
 204
 205         for (i = 0; i < n; i++) {
 206             int hexit = hexit_value(in[-i]);
 207             if (hexit < 0) {
 208                 return xasprintf("%s: bad hex digit in value", full_s);
 209             }
 210             out[-(i / 2)] |= i % 2 ? hexit << 4 : hexit;
 211         }
 212         s = arrow;
 213     } else {
 214         ovs_be64 *last_be64 = &imm.be64[ARRAY_SIZE(imm.be64) - 1];
 215         *last_be64 = htonll(strtoull(s, (char **) &s, 0));
 216     }
 217
 218     if (strncmp(s, "->", 2)) {
 219         return xasprintf("%s: missing `->' following value", full_s);
 220     }
 221     s += 2;
 222
 223     error = mf_parse_subfield(&dst, s);
 224     if (error) {
 225         return error;
 226     }
 227     if (!mf_nxm_header(dst.field->id)) {
 228         return xasprintf("%s: experimenter OXM field '%s' not supported",
 229                          full_s, s);
 230     }
 231
 232     if (!bitwise_is_all_zeros(&imm, sizeof imm, dst.n_bits,
 233                               (8 * sizeof imm) - dst.n_bits)) {
 234         return xasprintf("%s: value does not fit into %u bits",
 235                          full_s, dst.n_bits);
 236     }
 237
 238     spec->n_bits = dst.n_bits;
 239     spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 240     spec->src_imm = imm;
 241     spec->dst_type = NX_LEARN_DST_LOAD;
 242     spec->dst = dst;
 243     return NULL;
 244 }
 245
 246 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 247  * error.  The caller is responsible for freeing the returned string. */
 248 static char * WARN_UNUSED_RESULT
 249 learn_parse_spec(const char *orig, char *name, char *value,
 250                  struct ofpact_learn_spec *spec)
 251 {
 252     if (mf_from_name(name)) {
 253         const struct mf_field *dst = mf_from_name(name);
 254         union mf_value imm;
 255         char *error;
 256
 257         error = mf_parse_value(dst, value, &imm);
 258         if (error) {
 259             return error;
 260         }
 261
 262         spec->n_bits = dst->n_bits;
 263         spec->src_type = NX_LEARN_SRC_IMMEDIATE;
 264         memset(&spec->src_imm, 0, sizeof spec->src_imm);
 265         memcpy(&spec->src_imm.u8[sizeof spec->src_imm - dst->n_bytes],
 266                &imm, dst->n_bytes);
 267         spec->dst_type = NX_LEARN_DST_MATCH;
 268         spec->dst.field = dst;
 269         spec->dst.ofs = 0;
 270         spec->dst.n_bits = dst->n_bits;
 271     } else if (strchr(name, '[')) {
 272         /* Parse destination and check prerequisites. */
 273         char *error;
 274
 275         error = mf_parse_subfield(&spec->dst, name);
 276         if (error) {
 277             return error;
 278         }
 279         if (!mf_nxm_header(spec->dst.field->id)) {
 280             return xasprintf("%s: experimenter OXM field '%s' not supported",
 281                              orig, name);
 282         }
 283
 284         /* Parse source and check prerequisites. */
 285         if (value[0] != '\0') {
 286             error = mf_parse_subfield(&spec->src, value);
 287             if (error) {
 288                 return error;
 289             }
 290             if (spec->src.n_bits != spec->dst.n_bits) {
 291                 return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
 292                                  "differ", orig, name, spec->src.n_bits, value,
 293                                  spec->dst.n_bits);
 294             }
 295         } else {
 296             spec->src = spec->dst;
 297         }
 298
 299         spec->n_bits = spec->src.n_bits;
 300         spec->src_type = NX_LEARN_SRC_FIELD;
 301         spec->dst_type = NX_LEARN_DST_MATCH;
 302     } else if (!strcmp(name, "load")) {
 303         if (value[strcspn(value, "[-")] == '-') {
 304             char *error = learn_parse_load_immediate(value, spec);
 305             if (error) {
 306                 return error;
 307             }
 308         } else {
 309             struct ofpact_reg_move move;
 310             char *error;
 311
 312             error = nxm_parse_reg_move(&move, value);
 313             if (error) {
 314                 return error;
 315             }
 316
 317             spec->n_bits = move.src.n_bits;
 318             spec->src_type = NX_LEARN_SRC_FIELD;
 319             spec->src = move.src;
 320             spec->dst_type = NX_LEARN_DST_LOAD;
 321             spec->dst = move.dst;
 322         }
 323     } else if (!strcmp(name, "output")) {
 324         char *error = mf_parse_subfield(&spec->src, value);
 325         if (error) {
 326             return error;
 327         }
 328
 329         spec->n_bits = spec->src.n_bits;
 330         spec->src_type = NX_LEARN_SRC_FIELD;
 331         spec->dst_type = NX_LEARN_DST_OUTPUT;
 332     } else {
 333         return xasprintf("%s: unknown keyword %s", orig, name);
 334     }
 335
 336     return NULL;
 337 }
 338
 339 /* Returns NULL if successful, otherwise a malloc()'d string describing the
 340  * error.  The caller is responsible for freeing the returned string. */
 341 static char * WARN_UNUSED_RESULT
 342 learn_parse__(char *orig, char *arg, struct ofpbuf *ofpacts)
 343 {
 344     struct ofpact_learn *learn;
 345     struct match match;
 346     char *name, *value;
 347
 348     learn = ofpact_put_LEARN(ofpacts);
 349     learn->idle_timeout = OFP_FLOW_PERMANENT;
 350     learn->hard_timeout = OFP_FLOW_PERMANENT;
 351     learn->priority = OFP_DEFAULT_PRIORITY;
 352     learn->table_id = 1;
 353
 354     match_init_catchall(&match);
 355     while (ofputil_parse_key_value(&arg, &name, &value)) {
 356         if (!strcmp(name, "table")) {
 357             learn->table_id = atoi(value);
 358             if (learn->table_id == 255) {
 359                 return xasprintf("%s: table id 255 not valid for `learn' "
 360                                  "action", orig);
 361             }
 362         } else if (!strcmp(name, "priority")) {
 363             learn->priority = atoi(value);
 364         } else if (!strcmp(name, "idle_timeout")) {
 365             learn->idle_timeout = atoi(value);
 366         } else if (!strcmp(name, "hard_timeout")) {
 367             learn->hard_timeout = atoi(value);
 368         } else if (!strcmp(name, "fin_idle_timeout")) {
 369             learn->fin_idle_timeout = atoi(value);
 370         } else if (!strcmp(name, "fin_hard_timeout")) {
 371             learn->fin_hard_timeout = atoi(value);
 372         } else if (!strcmp(name, "cookie")) {
 373             learn->cookie = htonll(strtoull(value, NULL, 0));
 374         } else if (!strcmp(name, "send_flow_rem")) {
 375             learn->flags |= NX_LEARN_F_SEND_FLOW_REM;
 376         } else if (!strcmp(name, "delete_learned")) {
 377             learn->flags |= NX_LEARN_F_DELETE_LEARNED;
 378         } else {
 379             struct ofpact_learn_spec *spec;
 380             char *error;
 381
 382             spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
 383             learn = ofpacts->frame;
 384             learn->n_specs++;
 385
 386             error = learn_parse_spec(orig, name, value, spec);
 387             if (error) {
 388                 return error;
 389             }
 390
 391             /* Update 'match' to allow for satisfying destination
 392              * prerequisites. */
 393             if (spec->src_type == NX_LEARN_SRC_IMMEDIATE
 394                 && spec->dst_type == NX_LEARN_DST_MATCH) {
 395                 mf_write_subfield(&spec->dst, &spec->src_imm, &match);
 396             }
 397         }
 398     }
 399     ofpact_update_len(ofpacts, &learn->ofpact);
 400
 401     return NULL;
 402 }
 403
 404 /* Parses 'arg' as a set of arguments to the "learn" action and appends a
 405  * matching OFPACT_LEARN action to 'ofpacts'.  ovs-ofctl(8) describes the
 406  * format parsed.
 407  *
 408  * Returns NULL if successful, otherwise a malloc()'d string describing the
 409  * error.  The caller is responsible for freeing the returned string.
 410  *
 411  * If 'flow' is nonnull, then it should be the flow from a struct match that is
 412  * the matching rule for the learning action.  This helps to better validate
 413  * the action's arguments.
 414  *
 415  * Modifies 'arg'. */
 416 char * WARN_UNUSED_RESULT
 417 learn_parse(char *arg, struct ofpbuf *ofpacts)
 418 {
 419     char *orig = xstrdup(arg);
 420     char *error = learn_parse__(orig, arg, ofpacts);
 421     free(orig);
 422     return error;
 423 }
 424
 425 /* Appends a description of 'learn' to 's', in the format that ovs-ofctl(8)
 426  * describes. */
 427 void
 428 learn_format(const struct ofpact_learn *learn, struct ds *s)
 429 {
 430     const struct ofpact_learn_spec *spec;
 431     struct match match;
 432
 433     match_init_catchall(&match);
 434
 435     ds_put_format(s, "learn(table=%"PRIu8, learn->table_id);
 436     if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
 437         ds_put_format(s, ",idle_timeout=%"PRIu16, learn->idle_timeout);
 438     }
 439     if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
 440         ds_put_format(s, ",hard_timeout=%"PRIu16, learn->hard_timeout);
 441     }
 442     if (learn->fin_idle_timeout) {
 443         ds_put_format(s, ",fin_idle_timeout=%"PRIu16, learn->fin_idle_timeout);
 444     }
 445     if (learn->fin_hard_timeout) {
 446         ds_put_format(s, ",fin_hard_timeout=%"PRIu16, learn->fin_hard_timeout);
 447     }
 448     if (learn->priority != OFP_DEFAULT_PRIORITY) {
 449         ds_put_format(s, ",priority=%"PRIu16, learn->priority);
 450     }
 451     if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
 452         ds_put_cstr(s, ",send_flow_rem");
 453     }
 454     if (learn->flags & NX_LEARN_F_DELETE_LEARNED) {
 455         ds_put_cstr(s, ",delete_learned");
 456     }
 457     if (learn->cookie != 0) {
 458         ds_put_format(s, ",cookie=%#"PRIx64, ntohll(learn->cookie));
 459     }
 460
 461     for (spec = learn->specs; spec < &learn->specs[learn->n_specs]; spec++) {
 462         ds_put_char(s, ',');
 463
 464         switch (spec->src_type | spec->dst_type) {
 465         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH:
 466             if (spec->dst.ofs == 0
 467                 && spec->dst.n_bits == spec->dst.field->n_bits) {
 468                 union mf_value value;
 469
 470                 memset(&value, 0, sizeof value);
 471                 bitwise_copy(&spec->src_imm, sizeof spec->src_imm, 0,
 472                              &value, spec->dst.field->n_bytes, 0,
 473                              spec->dst.field->n_bits);
 474                 ds_put_format(s, "%s=", spec->dst.field->name);
 475                 mf_format(spec->dst.field, &value, NULL, s);
 476             } else {
 477                 mf_format_subfield(&spec->dst, s);
 478                 ds_put_char(s, '=');
 479                 mf_format_subvalue(&spec->src_imm, s);
 480             }
 481             break;
 482
 483         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
 484             mf_format_subfield(&spec->dst, s);
 485             if (spec->src.field != spec->dst.field ||
 486                 spec->src.ofs != spec->dst.ofs) {
 487                 ds_put_char(s, '=');
 488                 mf_format_subfield(&spec->src, s);
 489             }
 490             break;
 491
 492         case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
 493             ds_put_format(s, "load:");
 494             mf_format_subvalue(&spec->src_imm, s);
 495             ds_put_cstr(s, "->");
 496             mf_format_subfield(&spec->dst, s);
 497             break;
 498
 499         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
 500             ds_put_cstr(s, "load:");
 501             mf_format_subfield(&spec->src, s);
 502             ds_put_cstr(s, "->");
 503             mf_format_subfield(&spec->dst, s);
 504             break;
 505
 506         case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
 507             ds_put_cstr(s, "output:");
 508             mf_format_subfield(&spec->src, s);
 509             break;
 510         }
 511     }
 512     ds_put_char(s, ')');
 513 }