HttpHdrSc.cc

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/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */
 
/* DEBUG: section 90    HTTP Cache Control Header */
 
#include "squid.h"
#include "base/LookupTable.h"
//#include "HttpHdrSc.h" // pulled in by HttpHdrScTarget.h
#include "HttpHdrScTarget.h"
#include "HttpHeader.h"
#include "HttpHeaderFieldStat.h"
#include "HttpHeaderStat.h"
#include "HttpHeaderTools.h"
#include "Store.h"
#include "StrList.h"
#include "util.h"
 
#include <map>
#include <vector>
 
/* this table is used for parsing surrogate control header */
/* order must match that of enum http_hdr_sc_type. The constraint is verified at initialization time */
// TODO: implement constraint
static const LookupTable<http_hdr_sc_type>::Record ScAttrs[] {
    {"no-store", SC_NO_STORE},
    {"no-store-remote", SC_NO_STORE_REMOTE},
    {"max-age", SC_MAX_AGE},
    {"content", SC_CONTENT},
    {"Other,", SC_OTHER}, /* ',' will protect from matches */
    {nullptr, SC_ENUM_END} /* SC_ENUM_END taken as invalid value */
};
LookupTable<http_hdr_sc_type> scLookupTable(SC_ENUM_END, ScAttrs);
std::vector<HttpHeaderFieldStat> scHeaderStats(SC_ENUM_END);
 
// used when iterating over flags
http_hdr_sc_type &operator++ (http_hdr_sc_type &aHeader)
{
    int tmp = static_cast<int>(aHeader);
    aHeader = static_cast<http_hdr_sc_type>(++tmp);
    return aHeader;
}
 
void
httpHdrScInitModule(void)
{
    // check invariant on ScAttrs
    for (int i = 0; ScAttrs[i].name != nullptr; ++i)
        assert(i == ScAttrs[i].id);
}
 
/* implementation */
 
/* creates an sc object from a 0-terminating string */
HttpHdrSc *
httpHdrScParseCreate(const String & str)
{
    HttpHdrSc *sc = new HttpHdrSc();
 
    if (!sc->parse(&str)) {
        delete sc;
        sc = nullptr;
    }
 
    return sc;
}
 
/* parses a 0-terminating string and inits sc */
bool
HttpHdrSc::parse(const String * str)
{
    HttpHdrSc * sc=this;
    const char *item;
    const char *p;      /* '=' parameter */
    const char *pos = nullptr;
    const char *target = nullptr; /* ;foo */
    const char *temp = nullptr; /* temp buffer */
    http_hdr_sc_type type;
    int ilen, vlen;
    int initiallen;
    HttpHdrScTarget *sct;
    assert(str);
 
    /* iterate through comma separated list */
 
    while (strListGetItem(str, ',', &item, &ilen, &pos)) {
        initiallen = ilen;
        vlen = 0;
        /* decrease ilen to still match the token for  '=' statements */
 
        if ((p = strchr(item, '=')) && (p - item < ilen)) {
            vlen = ilen - (p + 1 - item);
            ilen = p - item;
            ++p;
        }
 
        /* decrease ilen to still match the token for ';' qualified non '=' statements */
        else if ((p = strchr(item, ';')) && (p - item < ilen)) {
            ilen = p - item;
            ++p;
        }
 
        /* find type */
        type = scLookupTable.lookup(SBuf(item,ilen));
 
        if (type == SC_ENUM_END) {
            debugs(90, 2, "unknown control-directive near '" << item << "' in '" << *str << "'");
            type = SC_OTHER;
        }
 
        /* Is this a targeted directive? */
        /* TODO: remove the temporary usage and use memrchr and the information we have instead */
        temp = xstrndup (item, initiallen + 1);
 
        if (!((target = strrchr (temp, ';')) && !strchr (target, '"') && *(target + 1) != '\0'))
            target = nullptr;
        else
            ++target;
 
        sct = sc->findTarget(target);
 
        if (!sct) {
            // XXX: if parse is left-to-right over field-value this should be emplace_back()
            // currently placing on the front reverses the order of headers passed on downstream.
            sct = &targets.emplace_front(target);
        }
 
        safe_free (temp);
 
        if (sct->isSet(type)) {
            if (type != SC_OTHER)
                debugs(90, 2, "ignoring duplicate control-directive near '" << item << "' in '" << *str << "'");
 
            ++ scHeaderStats[type].repCount;
 
            continue;
        }
 
        /* process directives */
        switch (type) {
        case SC_NO_STORE:
            sct->noStore(true);
            break;
 
        case SC_NO_STORE_REMOTE:
            sct->noStoreRemote(true);
            break;
 
        case SC_MAX_AGE: {
            int ma;
            if (p && httpHeaderParseInt(p, &ma)) {
                sct->maxAge(ma);
 
                if ((p = strchr (p, '+'))) {
                    int ms;
                    ++p; //skip the + char
                    if (httpHeaderParseInt(p, &ms)) {
                        sct->maxStale(ms);
                    } else {
                        debugs(90, 2, "sc: invalid max-stale specs near '" << item << "'");
                        sct->clearMaxStale();
                        /* leave the max-age alone */
                    }
                }
            } else {
                debugs(90, 2, "sc: invalid max-age specs near '" << item << "'");
                sct->clearMaxAge();
            }
 
            break;
        }
 
        case SC_CONTENT:
 
            if ( p && httpHeaderParseQuotedString(p, vlen, &sct->content_)) {
                sct->setMask(SC_CONTENT,true); // ugly but saves a copy
            } else {
                debugs(90, 2, "sc: invalid content= quoted string near '" << item << "'");
                sct->clearContent();
            }
            break;
 
        case SC_OTHER:
        default:
            break;
        }
    }
 
    return !sc->targets.empty();
}
 
void
HttpHdrScTarget::packInto(Packable * p) const
{
    http_hdr_sc_type flag;
    int pcount = 0;
    assert (p);
 
    for (flag = SC_NO_STORE; flag < SC_ENUM_END; ++flag) {
        if (isSet(flag) && flag != SC_OTHER) {
 
            /* print option name */
            p->appendf((pcount ? ", %s" : "%s"), ScAttrs[flag].name);
 
            /* handle options with values */
 
            if (flag == SC_MAX_AGE)
                p->appendf("=%d", (int) max_age);
 
            if (flag == SC_CONTENT)
                p->appendf("=\"" SQUIDSTRINGPH "\"", SQUIDSTRINGPRINT(content_));
 
            ++pcount;
        }
    }
 
    if (hasTarget())
        p->appendf(";" SQUIDSTRINGPH, SQUIDSTRINGPRINT(target));
}
 
void
HttpHdrSc::packInto(Packable * p) const
{
    assert(p);
    for (const auto &t : targets) {
        t.packInto(p);
    }
}
 
/* negative max_age will clean old max_Age setting */
void
HttpHdrSc::setMaxAge(char const *target, int max_age)
{
    HttpHdrScTarget *sct = findTarget(target);
 
    if (!sct) {
        sct = &targets.emplace_back(target);
    }
 
    sct->maxAge(max_age);
}
 
void
HttpHdrSc::updateStats(StatHist * hist) const
{
    for (auto &t : targets) {
        t.updateStats(hist);
    }
}
 
void
httpHdrScTargetStatDumper(StoreEntry * sentry, int, double val, double, int count)
{
    extern const HttpHeaderStat *dump_stat;     /* argh! */
    const int id = (int) val;
    const bool valid_id = id >= 0 && id < SC_ENUM_END;
    const char *name = valid_id ? ScAttrs[id].name : "INVALID";
 
    if (count || valid_id)
        storeAppendPrintf(sentry, "%2d\t %-20s\t %5d\t %6.2f\n",
                          id, name, count, xdiv(count, dump_stat->scParsedCount));
}
 
void
httpHdrScStatDumper(StoreEntry * sentry, int, double val, double, int count)
{
    extern const HttpHeaderStat *dump_stat; /* argh! */
    const int id = (int) val;
    const bool valid_id = id >= 0 && id < SC_ENUM_END;
    const char *name = valid_id ? ScAttrs[id].name : "INVALID";
 
    if (count || valid_id)
        storeAppendPrintf(sentry, "%2d\t %-20s\t %5d\t %6.2f\n",
                          id, name, count, xdiv(count, dump_stat->scParsedCount));
}
 
HttpHdrScTarget *
HttpHdrSc::findTarget(const char *target)
{
    for (auto &sct : targets) {
        if (sct.target.cmp(target) == 0)
            return &sct;
    }
 
    return nullptr;
}
 
HttpHdrScTarget *
HttpHdrSc::getMergedTarget(const char *ourtarget)
{
    HttpHdrScTarget *sctus = findTarget(ourtarget);
    HttpHdrScTarget *sctgeneric = findTarget(nullptr);
 
    /* W3C Edge Architecture Specification 1.0 section 3
     *
     * "If more than one is targeted at a surrogate, the most specific applies.
     *  For example,
     *    Surrogate-Control: max-age=60, no-store;abc
     *  The surrogate that identified itself as 'abc' would apply no-store;
     *  others would apply max-age=60.
     *
     * XXX: the if statements below will *merge* the no-store and max-age settings.
     */
    if (sctgeneric || sctus) {
        HttpHdrScTarget *sctusable = new HttpHdrScTarget(nullptr);
 
        if (sctgeneric)
            sctusable->mergeWith(sctgeneric);
 
        if (sctus)
            sctusable->mergeWith(sctus);
 
        return sctusable;
    }
 
    return nullptr;
}