+/*
+ * Copyright (c) 2010 Nicira Networks.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "nx-match.h"
+
+#include "classifier.h"
+#include "dynamic-string.h"
+#include "ofp-util.h"
+#include "ofpbuf.h"
+#include "openflow/nicira-ext.h"
+#include "packets.h"
+#include "unaligned.h"
+#include "vlog.h"
+
+VLOG_DEFINE_THIS_MODULE(nx_match);
+
+/* Rate limit for nx_match parse errors. These always indicate a bug in the
+ * peer and so there's not much point in showing a lot of them. */
+static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+
+enum {
+ NXM_INVALID = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_INVALID),
+ NXM_BAD_TYPE = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_BAD_TYPE),
+ NXM_BAD_VALUE = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_BAD_VALUE),
+ NXM_BAD_MASK = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_BAD_MASK),
+ NXM_BAD_PREREQ = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_BAD_PREREQ),
+ NXM_DUP_TYPE = OFP_MKERR_NICIRA(OFPET_BAD_REQUEST, NXBRC_NXM_DUP_TYPE),
+ BAD_ARGUMENT = OFP_MKERR(OFPET_BAD_ACTION, OFPBAC_BAD_ARGUMENT)
+};
+
+/* For each NXM_* field, define NFI_NXM_* as consecutive integers starting from
+ * zero. */
+enum nxm_field_index {
+#define DEFINE_FIELD(HEADER, WILDCARD, DL_TYPE, NW_PROTO) NFI_NXM_##HEADER,
+#include "nx-match.def"
+ N_NXM_FIELDS
+};
+
+struct nxm_field {
+ struct hmap_node hmap_node;
+ enum nxm_field_index index; /* NFI_* value. */
+ uint32_t header; /* NXM_* value. */
+ uint32_t wildcard; /* Wildcard bit, if exactly one. */
+ ovs_be16 dl_type; /* dl_type prerequisite, if nonzero. */
+ uint8_t nw_proto; /* nw_proto prerequisite, if nonzero. */
+ const char *name; /* "NXM_*" string. */
+};
+
+/* All the known fields. */
+static struct nxm_field nxm_fields[N_NXM_FIELDS] = {
+#define DEFINE_FIELD(HEADER, WILDCARD, DL_TYPE, NW_PROTO) \
+ { HMAP_NODE_NULL_INITIALIZER, NFI_NXM_##HEADER, NXM_##HEADER, WILDCARD, \
+ CONSTANT_HTONS(DL_TYPE), NW_PROTO, "NXM_" #HEADER },
+#include "nx-match.def"
+};
+
+/* Hash table of 'nxm_fields'. */
+static struct hmap all_nxm_fields = HMAP_INITIALIZER(&all_nxm_fields);
+
+static void
+nxm_init(void)
+{
+ if (hmap_is_empty(&all_nxm_fields)) {
+ int i;
+
+ for (i = 0; i < N_NXM_FIELDS; i++) {
+ struct nxm_field *f = &nxm_fields[i];
+ hmap_insert(&all_nxm_fields, &f->hmap_node,
+ hash_int(f->header, 0));
+ }
+
+ /* Verify that the header values are unique (duplicate "case" values
+ * cause a compile error). */
+ switch (0) {
+#define DEFINE_FIELD(HEADER, WILDCARD, DL_TYPE, NW_PROTO) \
+ case NXM_##HEADER: break;
+#include "nx-match.def"
+ }
+ }
+}
+
+static const struct nxm_field *
+nxm_field_lookup(uint32_t header)
+{
+ struct nxm_field *f;
+
+ nxm_init();
+
+ HMAP_FOR_EACH_WITH_HASH (f, hmap_node, hash_int(header, 0),
+ &all_nxm_fields) {
+ if (f->header == header) {
+ return f;
+ }
+ }
+
+ return NULL;
+}
+
+/* Returns the width of the data for a field with the given 'header', in
+ * bytes. */
+static int
+nxm_field_bytes(uint32_t header)
+{
+ unsigned int length = NXM_LENGTH(header);
+ return NXM_HASMASK(header) ? length / 2 : length;
+}
+\f
+/* nx_pull_match() and helpers. */
+
+static int
+parse_tci(struct cls_rule *rule, ovs_be16 tci, ovs_be16 mask)
+{
+ enum { OFPFW_DL_TCI = OFPFW_DL_VLAN | OFPFW_DL_VLAN_PCP };
+ if ((rule->wc.wildcards & OFPFW_DL_TCI) != OFPFW_DL_TCI) {
+ return NXM_DUP_TYPE;
+ } else {
+ return cls_rule_set_dl_tci_masked(rule, tci, mask) ? 0 : NXM_INVALID;
+ }
+}
+
+static int
+parse_nxm_entry(struct cls_rule *rule, const struct nxm_field *f,
+ const void *value, const void *mask)
+{
+ struct flow_wildcards *wc = &rule->wc;
+ struct flow *flow = &rule->flow;
+
+ switch (f->index) {
+ /* Metadata. */
+ case NFI_NXM_OF_IN_PORT:
+ flow->in_port = ntohs(get_unaligned_u16(value));
+ if (flow->in_port == OFPP_LOCAL) {
+ flow->in_port = ODPP_LOCAL;
+ }
+ return 0;
+
+ /* Ethernet header. */
+ case NFI_NXM_OF_ETH_DST:
+ memcpy(flow->dl_dst, value, ETH_ADDR_LEN);
+ return 0;
+ case NFI_NXM_OF_ETH_SRC:
+ memcpy(flow->dl_src, value, ETH_ADDR_LEN);
+ return 0;
+ case NFI_NXM_OF_ETH_TYPE:
+ flow->dl_type = get_unaligned_u16(value);
+ return 0;
+
+ /* 802.1Q header. */
+ case NFI_NXM_OF_VLAN_TCI:
+ return parse_tci(rule, get_unaligned_u16(value), htons(UINT16_MAX));
+
+ case NFI_NXM_OF_VLAN_TCI_W:
+ return parse_tci(rule, get_unaligned_u16(value),
+ get_unaligned_u16(mask));
+
+ /* IP header. */
+ case NFI_NXM_OF_IP_TOS:
+ if (*(uint8_t *) value & 0x03) {
+ return NXM_BAD_VALUE;
+ } else {
+ flow->nw_tos = *(uint8_t *) value;
+ return 0;
+ }
+ case NFI_NXM_OF_IP_PROTO:
+ flow->nw_proto = *(uint8_t *) value;
+ return 0;
+
+ /* IP addresses in IP and ARP headers. */
+ case NFI_NXM_OF_IP_SRC:
+ case NFI_NXM_OF_ARP_SPA:
+ if (wc->nw_src_mask) {
+ return NXM_DUP_TYPE;
+ } else {
+ cls_rule_set_nw_src(rule, get_unaligned_u32(value));
+ return 0;
+ }
+ case NFI_NXM_OF_IP_SRC_W:
+ case NFI_NXM_OF_ARP_SPA_W:
+ if (wc->nw_src_mask) {
+ return NXM_DUP_TYPE;
+ } else {
+ ovs_be32 ip = get_unaligned_u32(value);
+ ovs_be32 netmask = get_unaligned_u32(mask);
+ if (!cls_rule_set_nw_src_masked(rule, ip, netmask)) {
+ return NXM_BAD_MASK;
+ }
+ return 0;
+ }
+ case NFI_NXM_OF_IP_DST:
+ case NFI_NXM_OF_ARP_TPA:
+ if (wc->nw_dst_mask) {
+ return NXM_DUP_TYPE;
+ } else {
+ cls_rule_set_nw_dst(rule, get_unaligned_u32(value));
+ return 0;
+ }
+ case NFI_NXM_OF_IP_DST_W:
+ case NFI_NXM_OF_ARP_TPA_W:
+ if (wc->nw_dst_mask) {
+ return NXM_DUP_TYPE;
+ } else {
+ ovs_be32 ip = get_unaligned_u32(value);
+ ovs_be32 netmask = get_unaligned_u32(mask);
+ if (!cls_rule_set_nw_dst_masked(rule, ip, netmask)) {
+ return NXM_BAD_MASK;
+ }
+ return 0;
+ }
+
+ /* TCP header. */
+ case NFI_NXM_OF_TCP_SRC:
+ flow->tp_src = get_unaligned_u16(value);
+ return 0;
+ case NFI_NXM_OF_TCP_DST:
+ flow->tp_dst = get_unaligned_u16(value);
+ return 0;
+
+ /* UDP header. */
+ case NFI_NXM_OF_UDP_SRC:
+ flow->tp_src = get_unaligned_u16(value);
+ return 0;
+ case NFI_NXM_OF_UDP_DST:
+ flow->tp_dst = get_unaligned_u16(value);
+ return 0;
+
+ /* ICMP header. */
+ case NFI_NXM_OF_ICMP_TYPE:
+ flow->tp_src = htons(*(uint8_t *) value);
+ return 0;
+ case NFI_NXM_OF_ICMP_CODE:
+ flow->tp_dst = htons(*(uint8_t *) value);
+ return 0;
+
+ /* ARP header. */
+ case NFI_NXM_OF_ARP_OP:
+ if (ntohs(get_unaligned_u16(value)) > 255) {
+ return NXM_BAD_VALUE;
+ } else {
+ flow->nw_proto = ntohs(get_unaligned_u16(value));
+ return 0;
+ }
+
+ /* Tunnel ID. */
+ case NFI_NXM_NX_TUN_ID:
+ flow->tun_id = htonl(ntohll(get_unaligned_u64(value)));
+ return 0;
+
+ case N_NXM_FIELDS:
+ NOT_REACHED();
+ }
+ NOT_REACHED();
+}
+
+static bool
+nxm_prereqs_ok(const struct nxm_field *field, const struct flow *flow)
+{
+ return (!field->dl_type
+ || (field->dl_type == flow->dl_type
+ && (!field->nw_proto || field->nw_proto == flow->nw_proto)));
+}
+
+static uint32_t
+nx_entry_ok(const void *p, unsigned int match_len)
+{
+ unsigned int payload_len;
+ ovs_be32 header_be;
+ uint32_t header;
+
+ if (match_len < 4) {
+ if (match_len) {
+ VLOG_DBG_RL(&rl, "nx_match ends with partial nxm_header");
+ }
+ return 0;
+ }
+ memcpy(&header_be, p, 4);
+ header = ntohl(header_be);
+
+ payload_len = NXM_LENGTH(header);
+ if (!payload_len) {
+ VLOG_DBG_RL(&rl, "nxm_entry %08"PRIx32" has invalid payload "
+ "length 0", header);
+ return 0;
+ }
+ if (match_len < payload_len + 4) {
+ VLOG_DBG_RL(&rl, "%"PRIu32"-byte nxm_entry but only "
+ "%u bytes left in nx_match", payload_len + 4, match_len);
+ return 0;
+ }
+
+ return header;
+}
+
+int
+nx_pull_match(struct ofpbuf *b, unsigned int match_len, uint16_t priority,
+ struct cls_rule *rule)
+{
+ uint32_t header;
+ uint8_t *p;
+
+ p = ofpbuf_try_pull(b, ROUND_UP(match_len, 8));
+ if (!p) {
+ VLOG_DBG_RL(&rl, "nx_match length %zu, rounded up to a "
+ "multiple of 8, is longer than space in message (max "
+ "length %zu)", match_len, b->size);
+ return ofp_mkerr(OFPET_BAD_REQUEST, OFPBRC_BAD_LEN);
+ }
+
+ cls_rule_init_catchall(rule, priority);
+ while ((header = nx_entry_ok(p, match_len)) != 0) {
+ unsigned length = NXM_LENGTH(header);
+ const struct nxm_field *f;
+ int error;
+
+ f = nxm_field_lookup(header);
+ if (!f) {
+ error = NXM_BAD_TYPE;
+ } else if (!nxm_prereqs_ok(f, &rule->flow)) {
+ error = NXM_BAD_PREREQ;
+ } else if (f->wildcard && !(rule->wc.wildcards & f->wildcard)) {
+ error = NXM_DUP_TYPE;
+ } else {
+ /* 'hasmask' and 'length' are known to be correct at this point
+ * because they are included in 'header' and nxm_field_lookup()
+ * checked them already. */
+ rule->wc.wildcards &= ~f->wildcard;
+ error = parse_nxm_entry(rule, f, p + 4, p + 4 + length / 2);
+ }
+ if (error) {
+ VLOG_DBG_RL(&rl, "bad nxm_entry with vendor=%"PRIu32", "
+ "field=%"PRIu32", hasmask=%"PRIu32", type=%"PRIu32" "
+ "(error %x)",
+ NXM_VENDOR(header), NXM_FIELD(header),
+ NXM_HASMASK(header), NXM_TYPE(header),
+ error);
+ return error;
+ }
+
+
+ p += 4 + length;
+ match_len -= 4 + length;
+ }
+
+ return match_len ? NXM_INVALID : 0;
+}
+\f
+/* nx_put_match() and helpers.
+ *
+ * 'put' functions whose names end in 'w' add a wildcarded field.
+ * 'put' functions whose names end in 'm' add a field that might be wildcarded.
+ * Other 'put' functions add exact-match fields.
+ */
+
+static void
+nxm_put_header(struct ofpbuf *b, uint32_t header)
+{
+ ovs_be32 n_header = htonl(header);
+ ofpbuf_put(b, &n_header, sizeof n_header);
+}
+
+static void
+nxm_put_8(struct ofpbuf *b, uint32_t header, uint8_t value)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+}
+
+static void
+nxm_put_16(struct ofpbuf *b, uint32_t header, ovs_be16 value)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+}
+
+static void
+nxm_put_16w(struct ofpbuf *b, uint32_t header, ovs_be16 value, ovs_be16 mask)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+ ofpbuf_put(b, &mask, sizeof mask);
+}
+
+static void
+nxm_put_32(struct ofpbuf *b, uint32_t header, ovs_be32 value)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+}
+
+static void
+nxm_put_32w(struct ofpbuf *b, uint32_t header, ovs_be32 value, ovs_be32 mask)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+ ofpbuf_put(b, &mask, sizeof mask);
+}
+
+static void
+nxm_put_32m(struct ofpbuf *b, uint32_t header, ovs_be32 value, ovs_be32 mask)
+{
+ switch (mask) {
+ case 0:
+ break;
+
+ case UINT32_MAX:
+ nxm_put_32(b, header, value);
+ break;
+
+ default:
+ nxm_put_32w(b, NXM_MAKE_WILD_HEADER(header), value, mask);
+ break;
+ }
+}
+
+static void
+nxm_put_64(struct ofpbuf *b, uint32_t header, ovs_be64 value)
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, &value, sizeof value);
+}
+
+
+static void
+nxm_put_eth(struct ofpbuf *b, uint32_t header,
+ const uint8_t value[ETH_ADDR_LEN])
+{
+ nxm_put_header(b, header);
+ ofpbuf_put(b, value, ETH_ADDR_LEN);
+}
+
+int
+nx_put_match(struct ofpbuf *b, const struct cls_rule *cr)
+{
+ const uint32_t wc = cr->wc.wildcards;
+ const struct flow *flow = &cr->flow;
+ const size_t start_len = b->size;
+ ovs_be16 vid, pcp;
+ int match_len;
+
+ /* Metadata. */
+ if (!(wc & OFPFW_IN_PORT)) {
+ uint16_t in_port = flow->in_port;
+ if (in_port == ODPP_LOCAL) {
+ in_port = OFPP_LOCAL;
+ }
+ nxm_put_16(b, NXM_OF_IN_PORT, htons(in_port));
+ }
+
+ /* Ethernet. */
+ if (!(wc & OFPFW_DL_DST)) {
+ nxm_put_eth(b, NXM_OF_ETH_DST, flow->dl_dst);
+ }
+ if (!(wc & OFPFW_DL_SRC)) {
+ nxm_put_eth(b, NXM_OF_ETH_SRC, flow->dl_src);
+ }
+ if (!(wc & OFPFW_DL_TYPE)) {
+ nxm_put_16(b, NXM_OF_ETH_TYPE, flow->dl_type);
+ }
+
+ /* 802.1Q. */
+ vid = flow->dl_vlan & htons(VLAN_VID_MASK);
+ pcp = htons((flow->dl_vlan_pcp << VLAN_PCP_SHIFT) & VLAN_PCP_MASK);
+ switch (wc & (OFPFW_DL_VLAN | OFPFW_DL_VLAN_PCP)) {
+ case OFPFW_DL_VLAN | OFPFW_DL_VLAN_PCP:
+ break;
+ case OFPFW_DL_VLAN:
+ nxm_put_16w(b, NXM_OF_VLAN_TCI_W, pcp | htons(VLAN_CFI),
+ htons(VLAN_PCP_MASK | VLAN_CFI));
+ break;
+ case OFPFW_DL_VLAN_PCP:
+ if (flow->dl_vlan == htons(OFP_VLAN_NONE)) {
+ nxm_put_16(b, NXM_OF_VLAN_TCI, 0);
+ } else {
+ nxm_put_16w(b, NXM_OF_VLAN_TCI_W, vid | htons(VLAN_CFI),
+ htons(VLAN_VID_MASK | VLAN_CFI));
+ }
+ break;
+ case 0:
+ if (flow->dl_vlan == htons(OFP_VLAN_NONE)) {
+ nxm_put_16(b, NXM_OF_VLAN_TCI, 0);
+ } else {
+ nxm_put_16(b, NXM_OF_VLAN_TCI, vid | pcp | htons(VLAN_CFI));
+ }
+ break;
+ }
+
+ if (!(wc & OFPFW_DL_TYPE) && flow->dl_type == htons(ETH_TYPE_IP)) {
+ /* IP. */
+ if (!(wc & OFPFW_NW_TOS)) {
+ nxm_put_8(b, NXM_OF_IP_TOS, flow->nw_tos & 0xfc);
+ }
+ nxm_put_32m(b, NXM_OF_IP_SRC, flow->nw_src, cr->wc.nw_src_mask);
+ nxm_put_32m(b, NXM_OF_IP_DST, flow->nw_dst, cr->wc.nw_dst_mask);
+
+ if (!(wc & OFPFW_NW_PROTO)) {
+ nxm_put_8(b, NXM_OF_IP_PROTO, flow->nw_proto);
+ switch (flow->nw_proto) {
+ /* TCP. */
+ case IP_TYPE_TCP:
+ if (!(wc & OFPFW_TP_SRC)) {
+ nxm_put_16(b, NXM_OF_TCP_SRC, flow->tp_src);
+ }
+ if (!(wc & OFPFW_TP_DST)) {
+ nxm_put_16(b, NXM_OF_TCP_DST, flow->tp_dst);
+ }
+ break;
+
+ /* UDP. */
+ case IP_TYPE_UDP:
+ if (!(wc & OFPFW_TP_SRC)) {
+ nxm_put_16(b, NXM_OF_UDP_SRC, flow->tp_src);
+ }
+ if (!(wc & OFPFW_TP_DST)) {
+ nxm_put_16(b, NXM_OF_UDP_DST, flow->tp_dst);
+ }
+ break;
+
+ /* ICMP. */
+ case IP_TYPE_ICMP:
+ if (!(wc & OFPFW_TP_SRC)) {
+ nxm_put_8(b, NXM_OF_ICMP_TYPE, ntohs(flow->tp_src));
+ }
+ if (!(wc & OFPFW_TP_DST)) {
+ nxm_put_8(b, NXM_OF_ICMP_CODE, ntohs(flow->tp_dst));
+ }
+ break;
+ }
+ }
+ } else if (!(wc & OFPFW_DL_TYPE) && flow->dl_type == htons(ETH_TYPE_ARP)) {
+ /* ARP. */
+ if (!(wc & OFPFW_NW_PROTO)) {
+ nxm_put_16(b, NXM_OF_ARP_OP, htons(flow->nw_proto));
+ }
+ nxm_put_32m(b, NXM_OF_ARP_SPA, flow->nw_src, cr->wc.nw_src_mask);
+ nxm_put_32m(b, NXM_OF_ARP_TPA, flow->nw_dst, cr->wc.nw_dst_mask);
+ }
+
+ /* Tunnel ID. */
+ if (!(wc & NXFW_TUN_ID)) {
+ nxm_put_64(b, NXM_NX_TUN_ID, htonll(ntohl(flow->tun_id)));
+ }
+
+ match_len = b->size - start_len;
+ ofpbuf_put_zeros(b, ROUND_UP(match_len, 8) - match_len);
+ return match_len;
+}
+\f
+/* nx_match_to_string() and helpers. */
+
+char *
+nx_match_to_string(const uint8_t *p, unsigned int match_len)
+{
+ uint32_t header;
+ struct ds s;
+
+ if (!match_len) {
+ return xstrdup("<any>");
+ }
+
+ ds_init(&s);
+ while ((header = nx_entry_ok(p, match_len)) != 0) {
+ unsigned int length = NXM_LENGTH(header);
+ unsigned int value_len = nxm_field_bytes(header);
+ const uint8_t *value = p + 4;
+ const uint8_t *mask = value + value_len;
+ const struct nxm_field *f;
+ unsigned int i;
+
+ if (s.length) {
+ ds_put_cstr(&s, ", ");
+ }
+
+ f = nxm_field_lookup(header);
+ if (f) {
+ ds_put_cstr(&s, f->name);
+ } else {
+ ds_put_format(&s, "%d:%d", NXM_VENDOR(header), NXM_FIELD(header));
+ }
+
+ ds_put_char(&s, '(');
+
+ for (i = 0; i < value_len; i++) {
+ ds_put_format(&s, "%02x", value[i]);
+ }
+ if (NXM_HASMASK(header)) {
+ ds_put_char(&s, '/');
+ for (i = 0; i < value_len; i++) {
+ ds_put_format(&s, "%02x", mask[i]);
+ }
+ }
+ ds_put_char(&s, ')');
+
+ p += 4 + length;
+ match_len -= 4 + length;
+ }
+
+ if (match_len) {
+ if (s.length) {
+ ds_put_cstr(&s, ", ");
+ }
+
+ ds_put_format(&s, "<%u invalid bytes>", match_len);
+ }
+
+ return ds_steal_cstr(&s);
+}
+
+static const struct nxm_field *
+lookup_nxm_field(const char *name, int name_len)
+{
+ const struct nxm_field *f;
+
+ for (f = nxm_fields; f < &nxm_fields[ARRAY_SIZE(nxm_fields)]; f++) {
+ if (!strncmp(f->name, name, name_len) && f->name[name_len] == '\0') {
+ return f;
+ }
+ }
+
+ return NULL;
+}
+
+static const char *
+parse_hex_bytes(struct ofpbuf *b, const char *s, unsigned int n)
+{
+ while (n--) {
+ int low, high;
+ uint8_t byte;
+
+ s += strspn(s, " ");
+ low = hexit_value(*s);
+ high = low < 0 ? low : hexit_value(s[1]);
+ if (low < 0 || high < 0) {
+ ovs_fatal(0, "%.2s: hex digits expected", s);
+ }
+
+ byte = 16 * low + high;
+ ofpbuf_put(b, &byte, 1);
+ s += 2;
+ }
+ return s;
+}
+\f
+/* nx_match_from_string(). */
+
+int
+nx_match_from_string(const char *s, struct ofpbuf *b)
+{
+ const char *full_s = s;
+ const size_t start_len = b->size;
+ int match_len;
+
+ if (!strcmp(s, "<any>")) {
+ /* Ensure that 'b->data' isn't actually null. */
+ ofpbuf_prealloc_tailroom(b, 1);
+ return 0;
+ }
+
+ for (s += strspn(s, ", "); *s; s += strspn(s, ", ")) {
+ const struct nxm_field *f;
+ int name_len;
+
+ name_len = strcspn(s, "(");
+ if (s[name_len] != '(') {
+ ovs_fatal(0, "%s: missing ( at end of nx_match", full_s);
+ }
+
+ f = lookup_nxm_field(s, name_len);
+ if (!f) {
+ ovs_fatal(0, "%s: unknown field `%.*s'", full_s, name_len, s);
+ }
+
+ s += name_len + 1;
+
+ nxm_put_header(b, f->header);
+ s = parse_hex_bytes(b, s, nxm_field_bytes(f->header));
+ if (NXM_HASMASK(f->header)) {
+ s += strspn(s, " ");
+ if (*s != '/') {
+ ovs_fatal(0, "%s: missing / in masked field %s",
+ full_s, f->name);
+ }
+ s = parse_hex_bytes(b, s + 1, nxm_field_bytes(f->header));
+ }
+
+ s += strspn(s, " ");
+ if (*s != ')') {
+ ovs_fatal(0, "%s: missing ) following field %s", full_s, f->name);
+ }
+ s++;
+ }
+
+ match_len = b->size - start_len;
+ ofpbuf_put_zeros(b, ROUND_UP(match_len, 8) - match_len);
+ return match_len;
+}