ovs/lib/learn.c

/*
 * Copyright (c) 2011, 2012, 2013, 2014, 2015, 2016, 2017 Nicira, Inc.
 *
 * 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 "learn.h"

#include "byte-order.h"
#include "colors.h"
#include "nx-match.h"
#include "openflow/openflow.h"
#include "openvswitch/dynamic-string.h"
#include "openvswitch/match.h"
#include "openvswitch/meta-flow.h"
#include "openvswitch/ofp-actions.h"
#include "openvswitch/ofp-errors.h"
#include "openvswitch/ofp-flow.h"
#include "openvswitch/ofp-parse.h"
#include "openvswitch/ofp-table.h"
#include "openvswitch/ofpbuf.h"
#include "vl-mff-map.h"
#include "unaligned.h"


/* Checks that 'learn' is a valid action on 'flow'.  Returns 0 if it is valid,
 * otherwise an OFPERR_*. */
enum ofperr
learn_check(const struct ofpact_learn *learn, const struct match *src_match)
{
    const struct ofpact_learn_spec *spec;
    struct match dst_match;

    match_init_catchall(&dst_match);
    OFPACT_LEARN_SPEC_FOR_EACH (spec, learn) {
        enum ofperr error;

        /* Check the source. */
        if (spec->src_type == NX_LEARN_SRC_FIELD) {
            error = mf_check_src(&spec->src, src_match);
            if (error) {
                return error;
            }
        }

        /* Check the destination. */
        switch (spec->dst_type) {
        case NX_LEARN_DST_MATCH:
            error = mf_check_src(&spec->dst, &dst_match);
            if (error) {
                return error;
            }
            if (spec->src_type & NX_LEARN_SRC_IMMEDIATE) {
                mf_write_subfield_value(&spec->dst,
                                        ofpact_learn_spec_imm(spec),
                                        &dst_match);
            }
            break;

        case NX_LEARN_DST_LOAD:
            error = mf_check_dst(&spec->dst, &dst_match);
            if (error) {
                return error;
            }
            break;

        case NX_LEARN_DST_OUTPUT:
            /* Nothing to do. */
            break;
        }
    }
    return 0;
}

/* Composes 'fm' so that executing it will implement 'learn' given that the
 * packet being processed has 'flow' as its flow.
 *
 * Uses 'ofpacts' to store the flow mod's actions.  The caller must initialize
 * 'ofpacts' and retains ownership of it.  'fm->ofpacts' will point into the
 * 'ofpacts' buffer.
 *
 * The caller must eventually destroy fm->match.
 *
 * The caller has to actually execute 'fm'. */
void
learn_execute(const struct ofpact_learn *learn, const struct flow *flow,
              struct ofputil_flow_mod *fm, struct ofpbuf *ofpacts)
{
    const struct ofpact_learn_spec *spec;
    struct match match;

    match_init_catchall(&match);
    fm->priority = learn->priority;
    fm->cookie = htonll(0);
    fm->cookie_mask = htonll(0);
    fm->new_cookie = learn->cookie;
    fm->modify_cookie = fm->new_cookie != OVS_BE64_MAX;
    fm->table_id = learn->table_id;
    fm->command = OFPFC_MODIFY_STRICT;
    fm->idle_timeout = learn->idle_timeout;
    fm->hard_timeout = learn->hard_timeout;
    fm->importance = 0;
    fm->buffer_id = UINT32_MAX;
    fm->out_port = OFPP_NONE;
    fm->ofpacts_tlv_bitmap = 0;
    fm->flags = 0;
    if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
        fm->flags |= OFPUTIL_FF_SEND_FLOW_REM;
    }
    fm->ofpacts = NULL;
    fm->ofpacts_len = 0;

    if (learn->fin_idle_timeout || learn->fin_hard_timeout) {
        struct ofpact_fin_timeout *oft;

        oft = ofpact_put_FIN_TIMEOUT(ofpacts);
        oft->fin_idle_timeout = learn->fin_idle_timeout;
        oft->fin_hard_timeout = learn->fin_hard_timeout;
    }

    OFPACT_LEARN_SPEC_FOR_EACH (spec, learn) {
        struct ofpact_set_field *sf;
        union mf_subvalue value;

        if (spec->src_type == NX_LEARN_SRC_FIELD) {
            mf_read_subfield(&spec->src, flow, &value);
        } else {
            mf_subvalue_from_value(&spec->dst, &value,
                                   ofpact_learn_spec_imm(spec));
        }

        switch (spec->dst_type) {
        case NX_LEARN_DST_MATCH:
            mf_write_subfield(&spec->dst, &value, &match);
            match_add_ethernet_prereq(&match, spec->dst.field);
            mf_vl_mff_set_tlv_bitmap(
                spec->dst.field, &match.flow.tunnel.metadata.present.map);
            break;

        case NX_LEARN_DST_LOAD:
            sf = ofpact_put_reg_load(ofpacts, spec->dst.field, NULL, NULL);
            bitwise_copy(&value, sizeof value, 0,
                         sf->value, spec->dst.field->n_bytes, spec->dst.ofs,
                         spec->n_bits);
            bitwise_one(ofpact_set_field_mask(sf), spec->dst.field->n_bytes,
                        spec->dst.ofs, spec->n_bits);
            mf_vl_mff_set_tlv_bitmap(spec->dst.field, &fm->ofpacts_tlv_bitmap);
            break;

        case NX_LEARN_DST_OUTPUT:
            if (spec->n_bits <= 16
                || is_all_zeros(value.u8, sizeof value - 2)) {
                ofp_port_t port = u16_to_ofp(ntohll(value.integer));

                if (ofp_to_u16(port) < ofp_to_u16(OFPP_MAX)
                    || port == OFPP_IN_PORT
                    || port == OFPP_FLOOD
                    || port == OFPP_LOCAL
                    || port == OFPP_ALL) {
                    ofpact_put_OUTPUT(ofpacts)->port = port;
                }
            }
            break;
        }
    }

    minimatch_init(&fm->match, &match);
    fm->ofpacts = ofpacts->data;
    fm->ofpacts_len = ofpacts->size;
}

/* Perform a bitwise-OR on 'wc''s fields that are relevant as sources in
 * the learn action 'learn'. */
void
learn_mask(const struct ofpact_learn *learn, struct flow_wildcards *wc)
{
    const struct ofpact_learn_spec *spec;
    union mf_subvalue value;

    memset(&value, 0xff, sizeof value);
    OFPACT_LEARN_SPEC_FOR_EACH (spec, learn) {
        if (spec->src_type == NX_LEARN_SRC_FIELD) {
            mf_write_subfield_flow(&spec->src, &value, &wc->masks);
        }
    }
}

/* Returns NULL if successful, otherwise a malloc()'d string describing the
 * error.  The caller is responsible for freeing the returned string. */
static char * OVS_WARN_UNUSED_RESULT
learn_parse_load_immediate(union mf_subvalue *imm, const char *s,
                           const char *full_s, struct ofpact_learn_spec *spec,
                           struct ofpbuf *ofpacts)
{
    struct mf_subfield dst;
    char *error;

    error = mf_parse_subfield(&dst, s);
    if (error) {
        return error;
    }
    if (!mf_nxm_header(dst.field->id)) {
        return xasprintf("%s: experimenter OXM field '%s' not supported",
                         full_s, s);
    }

    if (!bitwise_is_all_zeros(imm, sizeof *imm, dst.n_bits,
                              (8 * sizeof *imm) - dst.n_bits)) {
        return xasprintf("%s: value does not fit into %u bits",
                         full_s, dst.n_bits);
    }

    spec->n_bits = dst.n_bits;
    spec->src_type = NX_LEARN_SRC_IMMEDIATE;
    spec->dst_type = NX_LEARN_DST_LOAD;
    spec->dst = dst;

    /* Push value last, as this may reallocate 'spec'! */
    unsigned int n_bytes = DIV_ROUND_UP(dst.n_bits, 8);
    uint8_t *src_imm = ofpbuf_put_zeros(ofpacts, OFPACT_ALIGN(n_bytes));
    memcpy(src_imm, &imm->u8[sizeof imm->u8 - n_bytes], n_bytes);

    return NULL;
}

/* Returns NULL if successful, otherwise a malloc()'d string describing the
 * error.  The caller is responsible for freeing the returned string. */
static char * OVS_WARN_UNUSED_RESULT
learn_parse_spec(const char *orig, char *name, char *value,
                 const struct ofputil_port_map *port_map,
                 struct ofpact_learn_spec *spec,
                 struct ofpbuf *ofpacts, struct match *match)
{
    /* Parse destination and check prerequisites. */
    struct mf_subfield dst;

    char *error = mf_parse_subfield(&dst, name);
    bool parse_error = error != NULL;
    free(error);

    if (!parse_error) {
        if (!mf_nxm_header(dst.field->id)) {
            return xasprintf("%s: experimenter OXM field '%s' not supported",
                             orig, name);
        }
        spec->dst = dst;
        spec->n_bits = dst.n_bits;
        spec->dst_type = NX_LEARN_DST_MATCH;

        /* Parse source and check prerequisites. */
        if (value[0] != '\0') {
            struct mf_subfield src;
            error = mf_parse_subfield(&src, value);
            if (error) {
                union mf_value imm;
                char *imm_error = NULL;

                /* Try an immediate value. */
                if (dst.ofs == 0 && dst.n_bits == dst.field->n_bits) {
                    /* Full field value. */
                    imm_error = mf_parse_value(dst.field, value, port_map,
                                               &imm);
                } else {
                    char *tail;
                    /* Partial field value. */
                    if (parse_int_string(value, (uint8_t *)&imm,
                                          dst.field->n_bytes, &tail)
                        || *tail != 0) {
                        imm_error = xasprintf("%s: cannot parse integer value", orig);
                    }

                    if (!imm_error &&
                        !bitwise_is_all_zeros(&imm, dst.field->n_bytes,
                                              dst.n_bits,
                                              dst.field->n_bytes * 8 - dst.n_bits)) {
                        struct ds ds;

                        ds_init(&ds);
                        mf_format(dst.field, &imm, NULL, NULL, &ds);
                        imm_error = xasprintf("%s: value %s does not fit into %d bits",
                                              orig, ds_cstr(&ds), dst.n_bits);
                        ds_destroy(&ds);
                    }
                }
                if (imm_error) {
                    char *err = xasprintf("%s: %s value %s cannot be parsed as a subfield (%s) or an immediate value (%s)",
                                          orig, name, value, error, imm_error);
                    free(error);
                    free(imm_error);
                    return err;
                }

                spec->src_type = NX_LEARN_SRC_IMMEDIATE;

                /* Update 'match' to allow for satisfying destination
                 * prerequisites. */
                mf_write_subfield_value(&dst, &imm, match);

                /* Push value last, as this may reallocate 'spec'! */
                unsigned int imm_bytes = DIV_ROUND_UP(dst.n_bits, 8);
                uint8_t *src_imm = ofpbuf_put_zeros(ofpacts,
                                                    OFPACT_ALIGN(imm_bytes));
                memcpy(src_imm, &imm, imm_bytes);

                free(error);
                return NULL;
            }
            spec->src = src;
            if (spec->src.n_bits != spec->dst.n_bits) {
                return xasprintf("%s: bit widths of %s (%u) and %s (%u) "
                                 "differ", orig, name, spec->src.n_bits, value,
                                 spec->dst.n_bits);
            }
        } else {
            spec->src = spec->dst;
        }

        spec->src_type = NX_LEARN_SRC_FIELD;
    } else if (!strcmp(name, "load")) {
        union mf_subvalue imm;
        char *tail;
        char *dst_value = strstr(value, "->");

        if (dst_value == value) {
            return xasprintf("%s: missing source before `->' in `%s'", name,
                             value);
        }
        if (!dst_value) {
            return xasprintf("%s: missing `->' in `%s'", name, value);
        }

        if (!parse_int_string(value, imm.u8, sizeof imm.u8, (char **) &tail)
            && tail != value) {
            if (tail != dst_value) {
                return xasprintf("%s: garbage before `->' in `%s'",
                                 name, value);
            }

            error = learn_parse_load_immediate(&imm, dst_value + 2, value, spec,
                                               ofpacts);
            if (error) {
                return error;
            }
        } else {
            struct ofpact_reg_move move;

            error = nxm_parse_reg_move(&move, value);
            if (error) {
                return error;
            }

            spec->n_bits = move.src.n_bits;
            spec->src_type = NX_LEARN_SRC_FIELD;
            spec->src = move.src;
            spec->dst_type = NX_LEARN_DST_LOAD;
            spec->dst = move.dst;
        }
    } else if (!strcmp(name, "output")) {
        error = mf_parse_subfield(&spec->src, value);
        if (error) {
            return error;
        }

        spec->n_bits = spec->src.n_bits;
        spec->src_type = NX_LEARN_SRC_FIELD;
        spec->dst_type = NX_LEARN_DST_OUTPUT;
    } else {
        return xasprintf("%s: unknown keyword %s", orig, name);
    }

    return NULL;
}

/* Returns NULL if successful, otherwise a malloc()'d string describing the
 * error.  The caller is responsible for freeing the returned string. */
static char * OVS_WARN_UNUSED_RESULT
learn_parse__(char *orig, char *arg, const struct ofputil_port_map *port_map,
              const struct ofputil_table_map *table_map,
              struct ofpbuf *ofpacts)
{
    struct ofpact_learn *learn;
    struct match match;
    char *name, *value;

    learn = ofpact_put_LEARN(ofpacts);
    learn->idle_timeout = OFP_FLOW_PERMANENT;
    learn->hard_timeout = OFP_FLOW_PERMANENT;
    learn->priority = OFP_DEFAULT_PRIORITY;
    learn->table_id = 1;

    match_init_catchall(&match);
    while (ofputil_parse_key_value(&arg, &name, &value)) {
        if (!strcmp(name, "table")) {
            if (!ofputil_table_from_string(value, table_map,
                                           &learn->table_id)) {
                return xasprintf("unknown table \"%s\"", value);
            } else if (learn->table_id == 255) {
                return xasprintf("%s: table id 255 not valid for `learn' "
                                 "action", orig);
            }
        } else if (!strcmp(name, "priority")) {
            learn->priority = atoi(value);
        } else if (!strcmp(name, "idle_timeout")) {
            learn->idle_timeout = atoi(value);
        } else if (!strcmp(name, "hard_timeout")) {
            learn->hard_timeout = atoi(value);
        } else if (!strcmp(name, "fin_idle_timeout")) {
            learn->fin_idle_timeout = atoi(value);
        } else if (!strcmp(name, "fin_hard_timeout")) {
            learn->fin_hard_timeout = atoi(value);
        } else if (!strcmp(name, "cookie")) {
            learn->cookie = htonll(strtoull(value, NULL, 0));
        } else if (!strcmp(name, "send_flow_rem")) {
            learn->flags |= NX_LEARN_F_SEND_FLOW_REM;
        } else if (!strcmp(name, "delete_learned")) {
            learn->flags |= NX_LEARN_F_DELETE_LEARNED;
        } else if (!strcmp(name, "limit")) {
            learn->limit = atoi(value);
        } else if (!strcmp(name, "result_dst")) {
            char *error;
            learn->flags |= NX_LEARN_F_WRITE_RESULT;
            error = mf_parse_subfield(&learn->result_dst, value);
            if (error) {
                return error;
            }
            if (!learn->result_dst.field->writable) {
                return xasprintf("%s is read-only", value);
            }
            if (learn->result_dst.n_bits != 1) {
                return xasprintf("result_dst in 'learn' action must be a "
                                 "single bit");
            }
        } else {
            struct ofpact_learn_spec *spec;
            char *error;

            spec = ofpbuf_put_zeros(ofpacts, sizeof *spec);
            error = learn_parse_spec(orig, name, value, port_map,
                                     spec, ofpacts, &match);
            if (error) {
                return error;
            }
            learn = ofpacts->header;
        }
    }
    ofpact_finish_LEARN(ofpacts, &learn);

    return NULL;
}

/* Parses 'arg' as a set of arguments to the "learn" action and appends a
 * matching OFPACT_LEARN action to 'ofpacts'.  ovs-actions(7) describes the
 * format parsed.
 *
 * Returns NULL if successful, otherwise a malloc()'d string describing the
 * error.  The caller is responsible for freeing the returned string.
 *
 * If 'flow' is nonnull, then it should be the flow from a struct match that is
 * the matching rule for the learning action.  This helps to better validate
 * the action's arguments.
 *
 * Modifies 'arg'. */
char * OVS_WARN_UNUSED_RESULT
learn_parse(char *arg, const struct ofputil_port_map *port_map,
            const struct ofputil_table_map *table_map,
            struct ofpbuf *ofpacts)
{
    char *orig = xstrdup(arg);
    char *error = learn_parse__(orig, arg, port_map, table_map, ofpacts);
    free(orig);
    return error;
}

/* Appends a description of 'learn' to 's', in the format that ovs-actions(7)
 * describes. */
void
learn_format(const struct ofpact_learn *learn,
             const struct ofputil_port_map *port_map,
             const struct ofputil_table_map *table_map,
             struct ds *s)
{
    const struct ofpact_learn_spec *spec;
    struct match match;

    match_init_catchall(&match);

    ds_put_format(s, "%slearn(%s%stable=%s",
                  colors.learn, colors.end, colors.special, colors.end);
    ofputil_format_table(learn->table_id, table_map, s);
    if (learn->idle_timeout != OFP_FLOW_PERMANENT) {
        ds_put_format(s, ",%sidle_timeout=%s%"PRIu16,
                      colors.param, colors.end, learn->idle_timeout);
    }
    if (learn->hard_timeout != OFP_FLOW_PERMANENT) {
        ds_put_format(s, ",%shard_timeout=%s%"PRIu16,
                      colors.param, colors.end, learn->hard_timeout);
    }
    if (learn->fin_idle_timeout) {
        ds_put_format(s, ",%sfin_idle_timeout=%s%"PRIu16,
                      colors.param, colors.end, learn->fin_idle_timeout);
    }
    if (learn->fin_hard_timeout) {
        ds_put_format(s, "%s,fin_hard_timeout=%s%"PRIu16,
                      colors.param, colors.end, learn->fin_hard_timeout);
    }
    if (learn->priority != OFP_DEFAULT_PRIORITY) {
        ds_put_format(s, "%s,priority=%s%"PRIu16,
                      colors.special, colors.end, learn->priority);
    }
    if (learn->flags & NX_LEARN_F_SEND_FLOW_REM) {
        ds_put_format(s, ",%ssend_flow_rem%s", colors.value, colors.end);
    }
    if (learn->flags & NX_LEARN_F_DELETE_LEARNED) {
        ds_put_format(s, ",%sdelete_learned%s", colors.value, colors.end);
    }
    if (learn->cookie != 0) {
        ds_put_format(s, ",%scookie=%s%#"PRIx64,
                      colors.param, colors.end, ntohll(learn->cookie));
    }
    if (learn->limit != 0) {
        ds_put_format(s, ",%slimit=%s%"PRIu32,
                      colors.param, colors.end, learn->limit);
    }
    if (learn->flags & NX_LEARN_F_WRITE_RESULT) {
        ds_put_format(s, ",%sresult_dst=%s", colors.param, colors.end);
        mf_format_subfield(&learn->result_dst, s);
    }

    OFPACT_LEARN_SPEC_FOR_EACH (spec, learn) {
        unsigned int n_bytes = DIV_ROUND_UP(spec->n_bits, 8);
        ds_put_char(s, ',');

        switch (spec->src_type | spec->dst_type) {
        case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_MATCH: {
            if (spec->dst.ofs == 0
                && spec->dst.n_bits == spec->dst.field->n_bits) {
                union mf_value value;

                memset(&value, 0, sizeof value);
                memcpy(&value.b[spec->dst.field->n_bytes - n_bytes],
                       ofpact_learn_spec_imm(spec), n_bytes);
                ds_put_format(s, "%s%s=%s", colors.param,
                              spec->dst.field->name, colors.end);
                mf_format(spec->dst.field, &value, NULL, port_map, s);
            } else {
                ds_put_format(s, "%s", colors.param);
                mf_format_subfield(&spec->dst, s);
                ds_put_format(s, "=%s", colors.end);
                ds_put_hex(s, ofpact_learn_spec_imm(spec), n_bytes);
            }
            break;
        }
        case NX_LEARN_SRC_FIELD | NX_LEARN_DST_MATCH:
            ds_put_format(s, "%s", colors.param);
            mf_format_subfield(&spec->dst, s);
            ds_put_format(s, "%s", colors.end);
            if (spec->src.field != spec->dst.field ||
                spec->src.ofs != spec->dst.ofs) {
                ds_put_format(s, "%s=%s", colors.param, colors.end);
                mf_format_subfield(&spec->src, s);
            }
            break;

        case NX_LEARN_SRC_IMMEDIATE | NX_LEARN_DST_LOAD:
            ds_put_format(s, "%sload:%s", colors.special, colors.end);
            ds_put_hex(s, ofpact_learn_spec_imm(spec), n_bytes);
            ds_put_format(s, "%s->%s", colors.special, colors.end);
            mf_format_subfield(&spec->dst, s);
            break;

        case NX_LEARN_SRC_FIELD | NX_LEARN_DST_LOAD:
            ds_put_format(s, "%sload:%s", colors.special, colors.end);
            mf_format_subfield(&spec->src, s);
            ds_put_format(s, "%s->%s", colors.special, colors.end);
            mf_format_subfield(&spec->dst, s);
            break;

        case NX_LEARN_SRC_FIELD | NX_LEARN_DST_OUTPUT:
            ds_put_format(s, "%soutput:%s", colors.special, colors.end);
            mf_format_subfield(&spec->src, s);
            break;
        }
    }
    ds_put_format(s, "%s)%s", colors.learn, colors.end);
}