/*
 * 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 00    Client Database */

#include "squid.h"
#include "base/RunnersRegistry.h"
#include "client_db.h"
#include "ClientInfo.h"
#include "event.h"
#include "format/Token.h"
#include "fqdncache.h"
#include "ip/Address.h"
#include "log/access_log.h"
#include "mgr/Registration.h"
#include "SquidConfig.h"
#include "SquidMath.h"
#include "StatCounters.h"
#include "Store.h"
#include "tools.h"

#if SQUID_SNMP
#include "snmp_core.h"
#endif

static hash_table *client_table = nullptr;

static ClientInfo *clientdbAdd(const Ip::Address &addr);
static FREE clientdbFreeItem;
static void clientdbStartGC(void);
static void clientdbScheduledGC(void *);

#if USE_DELAY_POOLS
static int max_clients = 32768;
#else
static int max_clients = 32;
#endif

static int cleanup_running = 0;
static int cleanup_scheduled = 0;
static int cleanup_removed;

#if USE_DELAY_POOLS
#define CLIENT_DB_HASH_SIZE 65357
#else
#define CLIENT_DB_HASH_SIZE 467
#endif

ClientInfo::ClientInfo(const Ip::Address &ip) :
#if USE_DELAY_POOLS
    BandwidthBucket(0, 0, 0),
#endif
    addr(ip),
    n_established(0),
    last_seen(0)
#if USE_DELAY_POOLS
    , writeLimitingActive(false),
    firstTimeConnection(true),
    quotaQueue(nullptr),
    rationedQuota(0),
    rationedCount(0),
    eventWaiting(false)
#endif
{
    debugs(77, 9, "ClientInfo constructed, this=" << static_cast<void*>(this));
    char *buf = static_cast<char*>(xmalloc(MAX_IPSTRLEN)); // becomes hash.key
    key = addr.toStr(buf,MAX_IPSTRLEN);
}

static ClientInfo *
clientdbAdd(const Ip::Address &addr)
{
    ClientInfo *c = new ClientInfo(addr);
    hash_join(client_table, static_cast<hash_link*>(c));
    ++statCounter.client_http.clients;

    if ((statCounter.client_http.clients > max_clients) && !cleanup_running && cleanup_scheduled < 2) {
        ++cleanup_scheduled;
        eventAdd("client_db garbage collector", clientdbScheduledGC, nullptr, 90, 0);
    }

    return c;
}

static void
clientdbInit(void)
{
    if (client_table)
        return;

    client_table = hash_create((HASHCMP *) strcmp, CLIENT_DB_HASH_SIZE, hash_string);
}

class ClientDbRr: public RegisteredRunner
{
public:
    /* RegisteredRunner API */
    void useConfig() override;
};
DefineRunnerRegistrator(ClientDbRr);

void
ClientDbRr::useConfig()
{
    clientdbInit();
    Mgr::RegisterAction("client_list", "Cache Client List", clientdbDump, 0, 1);
}

#if USE_DELAY_POOLS
/* returns ClientInfo for given IP addr
   Returns NULL if no such client (or clientdb turned off)
   (it is assumed that clientdbEstablished will be called before and create client record if needed)
*/
ClientInfo * clientdbGetInfo(const Ip::Address &addr)
{
    char key[MAX_IPSTRLEN];
    ClientInfo *c;

    if (!Config.onoff.client_db)
        return nullptr;

    addr.toStr(key,MAX_IPSTRLEN);

    c = (ClientInfo *) hash_lookup(client_table, key);
    if (c==nullptr) {
        debugs(77, DBG_IMPORTANT,"Client db does not contain information for given IP address "<<(const char*)key);
        return nullptr;
    }
    return c;
}
#endif
void
clientdbUpdate(const Ip::Address &addr, const LogTags &ltype, AnyP::ProtocolType p, size_t size)
{
    char key[MAX_IPSTRLEN];
    ClientInfo *c;

    if (!Config.onoff.client_db)
        return;

    addr.toStr(key,MAX_IPSTRLEN);

    c = (ClientInfo *) hash_lookup(client_table, key);

    if (c == nullptr)
        c = clientdbAdd(addr);

    if (c == nullptr)
        debug_trap("clientdbUpdate: Failed to add entry");

    if (p == AnyP::PROTO_HTTP) {
        ++ c->Http.n_requests;
        ++ c->Http.result_hist[ltype.oldType];
        c->Http.kbytes_out += size;

        if (ltype.isTcpHit())
            c->Http.hit_kbytes_out += size;
    } else if (p == AnyP::PROTO_ICP) {
        ++ c->Icp.n_requests;
        ++ c->Icp.result_hist[ltype.oldType];
        c->Icp.kbytes_out += size;

        if (LOG_UDP_HIT == ltype.oldType)
            c->Icp.hit_kbytes_out += size;
    }

    c->last_seen = squid_curtime;
}

/**
 * This function tracks the number of currently established connections
 * for a client IP address.  When a connection is accepted, call this
 * with delta = 1.  When the connection is closed, call with delta =
 * -1.  To get the current value, simply call with delta = 0.
 */
int
clientdbEstablished(const Ip::Address &addr, int delta)
{
    char key[MAX_IPSTRLEN];
    ClientInfo *c;

    if (!Config.onoff.client_db)
        return 0;

    addr.toStr(key,MAX_IPSTRLEN);

    c = (ClientInfo *) hash_lookup(client_table, key);

    if (c == nullptr) {
        c = clientdbAdd(addr);
    }

    if (c == nullptr)
        debug_trap("clientdbUpdate: Failed to add entry");

    c->n_established += delta;

    return c->n_established;
}

#define CUTOFF_SECONDS 3600
int

clientdbCutoffDenied(const Ip::Address &addr)
{
    char key[MAX_IPSTRLEN];
    int NR;
    int ND;
    double p;
    ClientInfo *c;

    if (!Config.onoff.client_db)
        return 0;

    addr.toStr(key,MAX_IPSTRLEN);

    c = (ClientInfo *) hash_lookup(client_table, key);

    if (c == nullptr)
        return 0;

    /*
     * If we are in a cutoff window, we don't send a reply
     */
    if (squid_curtime - c->cutoff.time < CUTOFF_SECONDS)
        return 1;

    /*
     * Calculate the percent of DENIED replies since the last
     * cutoff time.
     */
    NR = c->Icp.n_requests - c->cutoff.n_req;

    if (NR < 150)
        NR = 150;

    ND = c->Icp.result_hist[LOG_UDP_DENIED] - c->cutoff.n_denied;

    p = 100.0 * ND / NR;

    if (p < 95.0)
        return 0;

    debugs(1, DBG_CRITICAL, "WARNING: Probable misconfigured neighbor at " << key);

    debugs(1, DBG_CRITICAL, "WARNING: " << ND << " of the last " << NR <<
           " ICP replies are DENIED");

    debugs(1, DBG_CRITICAL, "WARNING: No replies will be sent for the next " <<
           CUTOFF_SECONDS << " seconds");

    c->cutoff.time = squid_curtime;

    c->cutoff.n_req = c->Icp.n_requests;

    c->cutoff.n_denied = c->Icp.result_hist[LOG_UDP_DENIED];

    return 1;
}

void
clientdbDump(StoreEntry * sentry)
{
    const char *name;
    int icp_total = 0;
    int icp_hits = 0;
    int http_total = 0;
    int http_hits = 0;
    storeAppendPrintf(sentry, "Cache Clients:\n");
    hash_first(client_table);

    while (hash_link *hash = hash_next(client_table)) {
        const ClientInfo *c = static_cast<const ClientInfo *>(hash);
        storeAppendPrintf(sentry, "Address: %s\n", hashKeyStr(hash));
        if ( (name = fqdncache_gethostbyaddr(c->addr, 0)) ) {
            storeAppendPrintf(sentry, "Name:    %s\n", name);
        }
        storeAppendPrintf(sentry, "Currently established connections: %d\n",
                          c->n_established);
        storeAppendPrintf(sentry, "    ICP  Requests %d\n",
                          c->Icp.n_requests);

        for (LogTags_ot l = LOG_TAG_NONE; l < LOG_TYPE_MAX; ++l) {
            if (c->Icp.result_hist[l] == 0)
                continue;

            icp_total += c->Icp.result_hist[l];

            if (LOG_UDP_HIT == l)
                icp_hits += c->Icp.result_hist[l];

            storeAppendPrintf(sentry, "        %-20.20s %7d %3d%%\n", LogTags(l).c_str(), c->Icp.result_hist[l], Math::intPercent(c->Icp.result_hist[l], c->Icp.n_requests));
        }

        storeAppendPrintf(sentry, "    HTTP Requests %d\n", c->Http.n_requests);

        for (LogTags_ot l = LOG_TAG_NONE; l < LOG_TYPE_MAX; ++l) {
            if (c->Http.result_hist[l] == 0)
                continue;

            http_total += c->Http.result_hist[l];

            if (LogTags(l).isTcpHit())
                http_hits += c->Http.result_hist[l];

            storeAppendPrintf(sentry,
                              "        %-20.20s %7d %3d%%\n",
                              LogTags(l).c_str(),
                              c->Http.result_hist[l],
                              Math::intPercent(c->Http.result_hist[l], c->Http.n_requests));
        }

        storeAppendPrintf(sentry, "\n");
    }

    storeAppendPrintf(sentry, "TOTALS\n");
    storeAppendPrintf(sentry, "ICP : %d Queries, %d Hits (%3d%%)\n",
                      icp_total, icp_hits, Math::intPercent(icp_hits, icp_total));
    storeAppendPrintf(sentry, "HTTP: %d Requests, %d Hits (%3d%%)\n",
                      http_total, http_hits, Math::intPercent(http_hits, http_total));
}

static void
clientdbFreeItem(void *data)
{
    ClientInfo *c = (ClientInfo *)data;
    delete c;
}

ClientInfo::~ClientInfo()
{
    safe_free(key);

#if USE_DELAY_POOLS
    if (CommQuotaQueue *q = quotaQueue) {
        q->clientInfo = nullptr;
        delete q; // invalidates cbdata, cancelling any pending kicks
    }
#endif

    debugs(77, 9, "ClientInfo destructed, this=" << static_cast<void*>(this));
}

static void
clientdbScheduledGC(void *)
{
    cleanup_scheduled = 0;
    clientdbStartGC();
}

static void
clientdbGC(void *)
{
    static int bucket = 0;
    hash_link *link_next;

    link_next = hash_get_bucket(client_table, bucket++);

    while (link_next != nullptr) {
        ClientInfo *c = (ClientInfo *)link_next;
        int age = squid_curtime - c->last_seen;
        link_next = link_next->next;

        if (c->n_established)
            continue;

        if (age < 24 * 3600 && c->Http.n_requests > 100)
            continue;

        if (age < 4 * 3600 && (c->Http.n_requests > 10 || c->Icp.n_requests > 10))
            continue;

        if (age < 5 * 60 && (c->Http.n_requests > 1 || c->Icp.n_requests > 1))
            continue;

        if (age < 60)
            continue;

        hash_remove_link(client_table, static_cast<hash_link*>(c));

        clientdbFreeItem(c);

        --statCounter.client_http.clients;

        ++cleanup_removed;
    }

    if (bucket < CLIENT_DB_HASH_SIZE)
        eventAdd("client_db garbage collector", clientdbGC, nullptr, 0.15, 0);
    else {
        bucket = 0;
        cleanup_running = 0;
        max_clients = statCounter.client_http.clients * 3 / 2;

        if (!cleanup_scheduled) {
            cleanup_scheduled = 1;
            eventAdd("client_db garbage collector", clientdbScheduledGC, nullptr, 6 * 3600, 0);
        }

        debugs(49, 2, "clientdbGC: Removed " << cleanup_removed << " entries");
    }
}

static void
clientdbStartGC(void)
{
    max_clients = statCounter.client_http.clients;
    cleanup_running = 1;
    cleanup_removed = 0;
    clientdbGC(nullptr);
}

#if SQUID_SNMP

Ip::Address *
client_entry(Ip::Address *current)
{
    char key[MAX_IPSTRLEN];
    hash_first(client_table);

    if (current) {
        current->toStr(key,MAX_IPSTRLEN);
        while (hash_link *hash = hash_next(client_table)) {
            if (!strcmp(key, hashKeyStr(hash)))
                break;
        }
    }

    ClientInfo *c = static_cast<ClientInfo *>(hash_next(client_table));

    hash_last(client_table);

    return c ? &c->addr : nullptr;
}

variable_list *
snmp_meshCtblFn(variable_list * Var, snint * ErrP)
{
    char key[MAX_IPSTRLEN];
    ClientInfo *c = nullptr;
    Ip::Address keyIp;

    *ErrP = SNMP_ERR_NOERROR;
    MemBuf tmp;
    debugs(49, 6, "Current : length=" << Var->name_length << ": " << snmpDebugOid(Var->name, Var->name_length, tmp));
    if (Var->name_length == 16) {
        oid2addr(&(Var->name[12]), keyIp, 4);
    } else if (Var->name_length == 28) {
        oid2addr(&(Var->name[12]), keyIp, 16);
    } else {
        *ErrP = SNMP_ERR_NOSUCHNAME;
        return nullptr;
    }

    keyIp.toStr(key, sizeof(key));
    debugs(49, 5, "[" << key << "] requested!");
    c = (ClientInfo *) hash_lookup(client_table, key);

    if (c == nullptr) {
        debugs(49, 5, "not found.");
        *ErrP = SNMP_ERR_NOSUCHNAME;
        return nullptr;
    }

    variable_list *Answer = nullptr;
    int aggr = 0;

    switch (Var->name[LEN_SQ_NET + 2]) {

    case MESH_CTBL_ADDR_TYPE: {
        int ival;
        ival = c->addr.isIPv4() ? INETADDRESSTYPE_IPV4 : INETADDRESSTYPE_IPV6 ;
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      ival, SMI_INTEGER);
    }
    break;

    case MESH_CTBL_ADDR: {
        Answer = snmp_var_new(Var->name, Var->name_length);
        // InetAddress doesn't have its own ASN.1 type,
        // like IpAddr does (SMI_IPADDRESS)
        // See: rfc4001.txt
        Answer->type = ASN_OCTET_STR;
        char client[MAX_IPSTRLEN];
        c->addr.toStr(client,MAX_IPSTRLEN);
        Answer->val_len = strlen(client);
        Answer->val.string =  (u_char *) xstrdup(client);
    }
    break;
    case MESH_CTBL_HTBYTES:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Http.kbytes_out.kb,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_HTREQ:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Http.n_requests,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_HTHITS:
        aggr = 0;

        for (LogTags_ot l = LOG_TAG_NONE; l < LOG_TYPE_MAX; ++l) {
            if (LogTags(l).isTcpHit())
                aggr += c->Http.result_hist[l];
        }

        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) aggr,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_HTHITBYTES:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Http.hit_kbytes_out.kb,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_ICPBYTES:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Icp.kbytes_out.kb,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_ICPREQ:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Icp.n_requests,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_ICPHITS:
        aggr = c->Icp.result_hist[LOG_UDP_HIT];
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) aggr,
                                      SMI_COUNTER32);
        break;

    case MESH_CTBL_ICPHITBYTES:
        Answer = snmp_var_new_integer(Var->name, Var->name_length,
                                      (snint) c->Icp.hit_kbytes_out.kb,
                                      SMI_COUNTER32);
        break;

    default:
        *ErrP = SNMP_ERR_NOSUCHNAME;
        debugs(49, 5, "snmp_meshCtblFn: illegal column.");
        break;
    }

    return Answer;
}

#endif /*SQUID_SNMP */

