lib/ofp-parse.c

   1 /*
   2  * Copyright (c) 2010 Nicira Networks.
   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 "ofp-parse.h"
  20
  21 #include <errno.h>
  22 #include <stdlib.h>
  23
  24 #include "byte-order.h"
  25 #include "dynamic-string.h"
  26 #include "netdev.h"
  27 #include "ofp-util.h"
  28 #include "ofpbuf.h"
  29 #include "openflow/openflow.h"
  30 #include "packets.h"
  31 #include "socket-util.h"
  32 #include "vconn.h"
  33 #include "vlog.h"
  34
  35 VLOG_DEFINE_THIS_MODULE(ofp_parse);
  36
  37 static uint32_t
  38 str_to_u32(const char *str)
  39 {
  40     char *tail;
  41     uint32_t value;
  42
  43     if (!str) {
  44         ovs_fatal(0, "missing required numeric argument");
  45     }
  46
  47     errno = 0;
  48     value = strtoul(str, &tail, 0);
  49     if (errno == EINVAL || errno == ERANGE || *tail) {
  50         ovs_fatal(0, "invalid numeric format %s", str);
  51     }
  52     return value;
  53 }
  54
  55 static uint64_t
  56 str_to_u64(const char *str)
  57 {
  58     char *tail;
  59     uint64_t value;
  60
  61     errno = 0;
  62     value = strtoull(str, &tail, 0);
  63     if (errno == EINVAL || errno == ERANGE || *tail) {
  64         ovs_fatal(0, "invalid numeric format %s", str);
  65     }
  66     return value;
  67 }
  68
  69 static void
  70 str_to_mac(const char *str, uint8_t mac[6])
  71 {
  72     if (sscanf(str, ETH_ADDR_SCAN_FMT, ETH_ADDR_SCAN_ARGS(mac))
  73         != ETH_ADDR_SCAN_COUNT) {
  74         ovs_fatal(0, "invalid mac address %s", str);
  75     }
  76 }
  77
  78 static void
  79 str_to_ip(const char *str_, ovs_be32 *ip, ovs_be32 *maskp)
  80 {
  81     char *str = xstrdup(str_);
  82     char *save_ptr = NULL;
  83     const char *name, *netmask;
  84     struct in_addr in_addr;
  85     ovs_be32 mask;
  86     int retval;
  87
  88     name = strtok_r(str, "/", &save_ptr);
  89     retval = name ? lookup_ip(name, &in_addr) : EINVAL;
  90     if (retval) {
  91         ovs_fatal(0, "%s: could not convert to IP address", str);
  92     }
  93     *ip = in_addr.s_addr;
  94
  95     netmask = strtok_r(NULL, "/", &save_ptr);
  96     if (netmask) {
  97         uint8_t o[4];
  98         if (sscanf(netmask, "%"SCNu8".%"SCNu8".%"SCNu8".%"SCNu8,
  99                    &o[0], &o[1], &o[2], &o[3]) == 4) {
 100             mask = htonl((o[0] << 24) | (o[1] << 16) | (o[2] << 8) | o[3]);
 101         } else {
 102             int prefix = atoi(netmask);
 103             if (prefix <= 0 || prefix > 32) {
 104                 ovs_fatal(0, "%s: network prefix bits not between 1 and 32",
 105                           str);
 106             } else if (prefix == 32) {
 107                 mask = htonl(UINT32_MAX);
 108             } else {
 109                 mask = htonl(((1u << prefix) - 1) << (32 - prefix));
 110             }
 111         }
 112     } else {
 113         mask = htonl(UINT32_MAX);
 114     }
 115     *ip &= mask;
 116
 117     if (maskp) {
 118         *maskp = mask;
 119     } else {
 120         if (mask != htonl(UINT32_MAX)) {
 121             ovs_fatal(0, "%s: netmask not allowed here", str_);
 122         }
 123     }
 124
 125     free(str);
 126 }
 127
 128 static void *
 129 put_action(struct ofpbuf *b, size_t size, uint16_t type)
 130 {
 131     struct ofp_action_header *ah = ofpbuf_put_zeros(b, size);
 132     ah->type = htons(type);
 133     ah->len = htons(size);
 134     return ah;
 135 }
 136
 137 static struct ofp_action_output *
 138 put_output_action(struct ofpbuf *b, uint16_t port)
 139 {
 140     struct ofp_action_output *oao = put_action(b, sizeof *oao, OFPAT_OUTPUT);
 141     oao->port = htons(port);
 142     return oao;
 143 }
 144
 145 static void
 146 put_enqueue_action(struct ofpbuf *b, uint16_t port, uint32_t queue)
 147 {
 148     struct ofp_action_enqueue *oae = put_action(b, sizeof *oae, OFPAT_ENQUEUE);
 149     oae->port = htons(port);
 150     oae->queue_id = htonl(queue);
 151 }
 152
 153 static void
 154 put_dl_addr_action(struct ofpbuf *b, uint16_t type, const char *addr)
 155 {
 156     struct ofp_action_dl_addr *oada = put_action(b, sizeof *oada, type);
 157     str_to_mac(addr, oada->dl_addr);
 158 }
 159
 160
 161 static bool
 162 parse_port_name(const char *name, uint16_t *port)
 163 {
 164     struct pair {
 165         const char *name;
 166         uint16_t value;
 167     };
 168     static const struct pair pairs[] = {
 169 #define DEF_PAIR(NAME) {#NAME, OFPP_##NAME}
 170         DEF_PAIR(IN_PORT),
 171         DEF_PAIR(TABLE),
 172         DEF_PAIR(NORMAL),
 173         DEF_PAIR(FLOOD),
 174         DEF_PAIR(ALL),
 175         DEF_PAIR(CONTROLLER),
 176         DEF_PAIR(LOCAL),
 177         DEF_PAIR(NONE),
 178 #undef DEF_PAIR
 179     };
 180     static const int n_pairs = ARRAY_SIZE(pairs);
 181     size_t i;
 182
 183     for (i = 0; i < n_pairs; i++) {
 184         if (!strcasecmp(name, pairs[i].name)) {
 185             *port = pairs[i].value;
 186             return true;
 187         }
 188     }
 189     return false;
 190 }
 191
 192 static void
 193 str_to_action(char *str, struct ofpbuf *b)
 194 {
 195     char *act, *arg;
 196     char *saveptr = NULL;
 197     bool drop = false;
 198     int n_actions;
 199
 200     for (act = strtok_r(str, ", \t\r\n", &saveptr), n_actions = 0; act;
 201          act = strtok_r(NULL, ", \t\r\n", &saveptr), n_actions++)
 202     {
 203         uint16_t port;
 204
 205         if (drop) {
 206             ovs_fatal(0, "Drop actions must not be followed by other actions");
 207         }
 208
 209         /* Arguments are separated by colons */
 210         arg = strchr(act, ':');
 211         if (arg) {
 212             *arg = '\0';
 213             arg++;
 214         }
 215
 216         if (!strcasecmp(act, "mod_vlan_vid")) {
 217             struct ofp_action_vlan_vid *va;
 218             va = put_action(b, sizeof *va, OFPAT_SET_VLAN_VID);
 219             va->vlan_vid = htons(str_to_u32(arg));
 220         } else if (!strcasecmp(act, "mod_vlan_pcp")) {
 221             struct ofp_action_vlan_pcp *va;
 222             va = put_action(b, sizeof *va, OFPAT_SET_VLAN_PCP);
 223             va->vlan_pcp = str_to_u32(arg);
 224         } else if (!strcasecmp(act, "strip_vlan")) {
 225             struct ofp_action_header *ah;
 226             ah = put_action(b, sizeof *ah, OFPAT_STRIP_VLAN);
 227             ah->type = htons(OFPAT_STRIP_VLAN);
 228         } else if (!strcasecmp(act, "mod_dl_src")) {
 229             put_dl_addr_action(b, OFPAT_SET_DL_SRC, arg);
 230         } else if (!strcasecmp(act, "mod_dl_dst")) {
 231             put_dl_addr_action(b, OFPAT_SET_DL_DST, arg);
 232         } else if (!strcasecmp(act, "mod_nw_src")) {
 233             struct ofp_action_nw_addr *na;
 234             na = put_action(b, sizeof *na, OFPAT_SET_NW_SRC);
 235             str_to_ip(arg, &na->nw_addr, NULL);
 236         } else if (!strcasecmp(act, "mod_nw_dst")) {
 237             struct ofp_action_nw_addr *na;
 238             na = put_action(b, sizeof *na, OFPAT_SET_NW_DST);
 239             str_to_ip(arg, &na->nw_addr, NULL);
 240         } else if (!strcasecmp(act, "mod_tp_src")) {
 241             struct ofp_action_tp_port *ta;
 242             ta = put_action(b, sizeof *ta, OFPAT_SET_TP_SRC);
 243             ta->tp_port = htons(str_to_u32(arg));
 244         } else if (!strcasecmp(act, "mod_tp_dst")) {
 245             struct ofp_action_tp_port *ta;
 246             ta = put_action(b, sizeof *ta, OFPAT_SET_TP_DST);
 247             ta->tp_port = htons(str_to_u32(arg));
 248         } else if (!strcasecmp(act, "mod_nw_tos")) {
 249             struct ofp_action_nw_tos *nt;
 250             nt = put_action(b, sizeof *nt, OFPAT_SET_NW_TOS);
 251             nt->nw_tos = str_to_u32(arg);
 252         } else if (!strcasecmp(act, "resubmit")) {
 253             struct nx_action_resubmit *nar;
 254             nar = put_action(b, sizeof *nar, OFPAT_VENDOR);
 255             nar->vendor = htonl(NX_VENDOR_ID);
 256             nar->subtype = htons(NXAST_RESUBMIT);
 257             nar->in_port = htons(str_to_u32(arg));
 258         } else if (!strcasecmp(act, "set_tunnel")) {
 259             struct nx_action_set_tunnel *nast;
 260             nast = put_action(b, sizeof *nast, OFPAT_VENDOR);
 261             nast->vendor = htonl(NX_VENDOR_ID);
 262             nast->subtype = htons(NXAST_SET_TUNNEL);
 263             nast->tun_id = htonl(str_to_u32(arg));
 264         } else if (!strcasecmp(act, "drop_spoofed_arp")) {
 265             struct nx_action_header *nah;
 266             nah = put_action(b, sizeof *nah, OFPAT_VENDOR);
 267             nah->vendor = htonl(NX_VENDOR_ID);
 268             nah->subtype = htons(NXAST_DROP_SPOOFED_ARP);
 269         } else if (!strcasecmp(act, "set_queue")) {
 270             struct nx_action_set_queue *nasq;
 271             nasq = put_action(b, sizeof *nasq, OFPAT_VENDOR);
 272             nasq->vendor = htonl(NX_VENDOR_ID);
 273             nasq->subtype = htons(NXAST_SET_QUEUE);
 274             nasq->queue_id = htonl(str_to_u32(arg));
 275         } else if (!strcasecmp(act, "pop_queue")) {
 276             struct nx_action_header *nah;
 277             nah = put_action(b, sizeof *nah, OFPAT_VENDOR);
 278             nah->vendor = htonl(NX_VENDOR_ID);
 279             nah->subtype = htons(NXAST_POP_QUEUE);
 280         } else if (!strcasecmp(act, "output")) {
 281             put_output_action(b, str_to_u32(arg));
 282         } else if (!strcasecmp(act, "enqueue")) {
 283             char *sp = NULL;
 284             char *port_s = strtok_r(arg, ":q", &sp);
 285             char *queue = strtok_r(NULL, "", &sp);
 286             if (port_s == NULL || queue == NULL) {
 287                 ovs_fatal(0, "\"enqueue\" syntax is \"enqueue:PORT:QUEUE\"");
 288             }
 289             put_enqueue_action(b, str_to_u32(port_s), str_to_u32(queue));
 290         } else if (!strcasecmp(act, "drop")) {
 291             /* A drop action in OpenFlow occurs by just not setting
 292              * an action. */
 293             drop = true;
 294             if (n_actions) {
 295                 ovs_fatal(0, "Drop actions must not be preceded by other "
 296                           "actions");
 297             }
 298         } else if (!strcasecmp(act, "CONTROLLER")) {
 299             struct ofp_action_output *oao;
 300             oao = put_output_action(b, OFPP_CONTROLLER);
 301
 302             /* Unless a numeric argument is specified, we send the whole
 303              * packet to the controller. */
 304             if (arg && (strspn(arg, "0123456789") == strlen(arg))) {
 305                oao->max_len = htons(str_to_u32(arg));
 306             } else {
 307                 oao->max_len = htons(UINT16_MAX);
 308             }
 309         } else if (parse_port_name(act, &port)) {
 310             put_output_action(b, port);
 311         } else if (strspn(act, "0123456789") == strlen(act)) {
 312             put_output_action(b, str_to_u32(act));
 313         } else {
 314             ovs_fatal(0, "Unknown action: %s", act);
 315         }
 316     }
 317 }
 318
 319 struct protocol {
 320     const char *name;
 321     uint16_t dl_type;
 322     uint8_t nw_proto;
 323 };
 324
 325 static bool
 326 parse_protocol(const char *name, const struct protocol **p_out)
 327 {
 328     static const struct protocol protocols[] = {
 329         { "ip", ETH_TYPE_IP, 0 },
 330         { "arp", ETH_TYPE_ARP, 0 },
 331         { "icmp", ETH_TYPE_IP, IP_TYPE_ICMP },
 332         { "tcp", ETH_TYPE_IP, IP_TYPE_TCP },
 333         { "udp", ETH_TYPE_IP, IP_TYPE_UDP },
 334     };
 335     const struct protocol *p;
 336
 337     for (p = protocols; p < &protocols[ARRAY_SIZE(protocols)]; p++) {
 338         if (!strcmp(p->name, name)) {
 339             *p_out = p;
 340             return true;
 341         }
 342     }
 343     *p_out = NULL;
 344     return false;
 345 }
 346
 347 #define FIELDS                                              \
 348     FIELD(F_IN_PORT,     "in_port",     OFPFW_IN_PORT)      \
 349     FIELD(F_DL_VLAN,     "dl_vlan",     OFPFW_DL_VLAN)      \
 350     FIELD(F_DL_VLAN_PCP, "dl_vlan_pcp", OFPFW_DL_VLAN_PCP)  \
 351     FIELD(F_DL_SRC,      "dl_src",      OFPFW_DL_SRC)       \
 352     FIELD(F_DL_DST,      "dl_dst",      OFPFW_DL_DST)       \
 353     FIELD(F_DL_TYPE,     "dl_type",     OFPFW_DL_TYPE)      \
 354     FIELD(F_NW_SRC,      "nw_src",      0)                  \
 355     FIELD(F_NW_DST,      "nw_dst",      0)                  \
 356     FIELD(F_NW_PROTO,    "nw_proto",    OFPFW_NW_PROTO)     \
 357     FIELD(F_NW_TOS,      "nw_tos",      OFPFW_NW_TOS)       \
 358     FIELD(F_TP_SRC,      "tp_src",      OFPFW_TP_SRC)       \
 359     FIELD(F_TP_DST,      "tp_dst",      OFPFW_TP_DST)       \
 360     FIELD(F_ICMP_TYPE,   "icmp_type",   OFPFW_ICMP_TYPE)    \
 361     FIELD(F_ICMP_CODE,   "icmp_code",   OFPFW_ICMP_CODE)
 362
 363 enum field_index {
 364 #define FIELD(ENUM, NAME, WILDCARD) ENUM,
 365     FIELDS
 366 #undef FIELD
 367     N_FIELDS
 368 };
 369
 370 struct field {
 371     enum field_index index;
 372     const char *name;
 373     uint32_t wildcard;
 374 };
 375
 376 static bool
 377 parse_field_name(const char *name, const struct field **f_out)
 378 {
 379     static const struct field fields[N_FIELDS] = {
 380 #define FIELD(ENUM, NAME, WILDCARD) { ENUM, NAME, WILDCARD },
 381         FIELDS
 382 #undef FIELD
 383     };
 384     const struct field *f;
 385
 386     for (f = fields; f < &fields[ARRAY_SIZE(fields)]; f++) {
 387         if (!strcmp(f->name, name)) {
 388             *f_out = f;
 389             return true;
 390         }
 391     }
 392     *f_out = NULL;
 393     return false;
 394 }
 395
 396 static void
 397 parse_field_value(struct cls_rule *rule, enum field_index index,
 398                   const char *value)
 399 {
 400     uint8_t mac[ETH_ADDR_LEN];
 401     ovs_be32 ip, mask;
 402     uint16_t port_no;
 403
 404     switch (index) {
 405     case F_IN_PORT:
 406         if (!parse_port_name(value, &port_no)) {
 407             port_no = atoi(value);
 408         }
 409         if (port_no == OFPP_LOCAL) {
 410             port_no = ODPP_LOCAL;
 411         }
 412         cls_rule_set_in_port(rule, port_no);
 413         break;
 414
 415     case F_DL_VLAN:
 416         cls_rule_set_dl_vlan(rule, htons(str_to_u32(value)));
 417         break;
 418
 419     case F_DL_VLAN_PCP:
 420         cls_rule_set_dl_vlan_pcp(rule, str_to_u32(value));
 421         break;
 422
 423     case F_DL_SRC:
 424         str_to_mac(value, mac);
 425         cls_rule_set_dl_src(rule, mac);
 426         break;
 427
 428     case F_DL_DST:
 429         str_to_mac(value, mac);
 430         cls_rule_set_dl_dst(rule, mac);
 431         break;
 432
 433     case F_DL_TYPE:
 434         cls_rule_set_dl_type(rule, htons(str_to_u32(value)));
 435         break;
 436
 437     case F_NW_SRC:
 438         str_to_ip(value, &ip, &mask);
 439         cls_rule_set_nw_src_masked(rule, ip, mask);
 440         break;
 441
 442     case F_NW_DST:
 443         str_to_ip(value, &ip, &mask);
 444         cls_rule_set_nw_dst_masked(rule, ip, mask);
 445         break;
 446
 447     case F_NW_PROTO:
 448         cls_rule_set_nw_proto(rule, str_to_u32(value));
 449         break;
 450
 451     case F_NW_TOS:
 452         cls_rule_set_nw_tos(rule, str_to_u32(value));
 453         break;
 454
 455     case F_TP_SRC:
 456         cls_rule_set_tp_src(rule, htons(str_to_u32(value)));
 457         break;
 458
 459     case F_TP_DST:
 460         cls_rule_set_tp_dst(rule, htons(str_to_u32(value)));
 461         break;
 462
 463     case F_ICMP_TYPE:
 464         cls_rule_set_icmp_type(rule, str_to_u32(value));
 465         break;
 466
 467     case F_ICMP_CODE:
 468         cls_rule_set_icmp_code(rule, str_to_u32(value));
 469         break;
 470
 471     case N_FIELDS:
 472         NOT_REACHED();
 473     }
 474 }
 475
 476 /* Convert 'string' (as described in the Flow Syntax section of the ovs-ofctl
 477  * man page) into 'pf'.  If 'actions' is specified, an action must be in
 478  * 'string' and may be expanded or reallocated. */
 479 void
 480 parse_ofp_str(struct parsed_flow *pf, struct ofpbuf *actions, char *string)
 481 {
 482     char *save_ptr = NULL;
 483     char *name;
 484
 485     cls_rule_init_catchall(&pf->rule, OFP_DEFAULT_PRIORITY);
 486     pf->table_idx = 0xff;
 487     pf->out_port = OFPP_NONE;
 488     pf->idle_timeout = OFP_FLOW_PERMANENT;
 489     pf->hard_timeout = OFP_FLOW_PERMANENT;
 490     pf->cookie = 0;
 491     if (actions) {
 492         char *act_str = strstr(string, "action");
 493         if (!act_str) {
 494             ovs_fatal(0, "must specify an action");
 495         }
 496         *act_str = '\0';
 497
 498         act_str = strchr(act_str + 1, '=');
 499         if (!act_str) {
 500             ovs_fatal(0, "must specify an action");
 501         }
 502
 503         act_str++;
 504
 505         str_to_action(act_str, actions);
 506     }
 507     for (name = strtok_r(string, "=, \t\r\n", &save_ptr); name;
 508          name = strtok_r(NULL, "=, \t\r\n", &save_ptr)) {
 509         const struct protocol *p;
 510
 511         if (parse_protocol(name, &p)) {
 512             cls_rule_set_dl_type(&pf->rule, htons(p->dl_type));
 513             if (p->nw_proto) {
 514                 cls_rule_set_nw_proto(&pf->rule, p->nw_proto);
 515             }
 516         } else {
 517             const struct field *f;
 518             char *value;
 519
 520             value = strtok_r(NULL, ", \t\r\n", &save_ptr);
 521             if (!value) {
 522                 ovs_fatal(0, "field %s missing value", name);
 523             }
 524
 525             if (!strcmp(name, "table")) {
 526                 pf->table_idx = atoi(value);
 527             } else if (!strcmp(name, "out_port")) {
 528                 pf->out_port = atoi(value);
 529             } else if (!strcmp(name, "priority")) {
 530                 pf->rule.priority = atoi(value);
 531             } else if (!strcmp(name, "idle_timeout")) {
 532                 pf->idle_timeout = atoi(value);
 533             } else if (!strcmp(name, "hard_timeout")) {
 534                 pf->hard_timeout = atoi(value);
 535             } else if (!strcmp(name, "cookie")) {
 536                 pf->cookie = str_to_u64(value);
 537             } else if (parse_field_name(name, &f)) {
 538                 if (!strcmp(value, "*") || !strcmp(value, "ANY")) {
 539                     if (f->wildcard) {
 540                         pf->rule.wc.wildcards |= f->wildcard;
 541                         cls_rule_zero_wildcarded_fields(&pf->rule);
 542                     } else if (f->index == F_NW_SRC) {
 543                         cls_rule_set_nw_src_masked(&pf->rule, 0, 0);
 544                     } else if (f->index == F_NW_DST) {
 545                         cls_rule_set_nw_dst_masked(&pf->rule, 0, 0);
 546                     } else {
 547                         NOT_REACHED();
 548                     }
 549                 } else {
 550                     parse_field_value(&pf->rule, f->index, value);
 551                 }
 552             } else {
 553                 ovs_fatal(0, "unknown keyword %s", name);
 554             }
 555         }
 556     }
 557 }
 558
 559 /* Parses 'string' as an OFPT_FLOW_MOD with command 'command' (one of OFPFC_*)
 560  * and returns an ofpbuf that contains it. */
 561 struct ofpbuf *
 562 parse_ofp_flow_mod_str(char *string, uint16_t command)
 563 {
 564     struct parsed_flow pf;
 565     struct ofpbuf *buffer;
 566     struct ofp_flow_mod *ofm;
 567
 568     /* parse_ofp_str() will expand and reallocate the data in 'buffer', so we
 569      * can't keep pointers to across the parse_ofp_str() call. */
 570     make_openflow(sizeof *ofm, OFPT_FLOW_MOD, &buffer);
 571     parse_ofp_str(&pf, buffer, string);
 572
 573     ofm = buffer->data;
 574     flow_to_match(&pf.rule.flow, pf.rule.wc.wildcards, NXFF_OPENFLOW10,
 575                   &ofm->match);
 576     ofm->command = htons(command);
 577     ofm->cookie = htonll(pf.cookie);
 578     ofm->idle_timeout = htons(pf.idle_timeout);
 579     ofm->hard_timeout = htons(pf.hard_timeout);
 580     ofm->buffer_id = htonl(UINT32_MAX);
 581     ofm->out_port = htons(pf.out_port);
 582     ofm->priority = htons(pf.rule.priority);
 583     update_openflow_length(buffer);
 584
 585     return buffer;
 586 }
 587
 588 /* Parses an OFPT_FLOW_MOD with subtype OFPFC_ADD from 'stream' and returns an
 589  * ofpbuf that contains it.  Returns a null pointer if end-of-file is reached
 590  * before reading a flow. */
 591 struct ofpbuf *
 592 parse_ofp_add_flow_file(FILE *stream)
 593 {
 594     struct ofpbuf *b = NULL;
 595     struct ds s = DS_EMPTY_INITIALIZER;
 596
 597     while (!ds_get_line(&s, stream)) {
 598         char *line = ds_cstr(&s);
 599         char *comment;
 600
 601         /* Delete comments. */
 602         comment = strchr(line, '#');
 603         if (comment) {
 604             *comment = '\0';
 605         }
 606
 607         /* Drop empty lines. */
 608         if (line[strspn(line, " \t\n")] == '\0') {
 609             continue;
 610         }
 611
 612         b = parse_ofp_flow_mod_str(line, OFPFC_ADD);
 613         break;
 614     }
 615     ds_destroy(&s);
 616
 617     return b;
 618 }