/*
 * Copyright (C) 1996-2021 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 30    Ident (RFC 931) */

#include "squid.h"

#if USE_IDENT
#include "comm.h"
#include "comm/Connection.h"
#include "comm/ConnOpener.h"
#include "comm/Read.h"
#include "comm/Write.h"
#include "CommCalls.h"
#include "globals.h"
#include "ident/Config.h"
#include "ident/Ident.h"
#include "MemBuf.h"

namespace Ident
{

#define IDENT_PORT 113
#define IDENT_KEY_SZ 50
#define IDENT_BUFSIZE 4096

typedef struct _IdentClient {
    IDCB *callback;
    void *callback_data;

    struct _IdentClient *next;
} IdentClient;

class IdentStateData
{
public:
    hash_link hash;     /* must be first */
private:
    CBDATA_CLASS(IdentStateData);

public:
    /* AsyncJob API emulated */
    void deleteThis(const char *aReason);
    void swanSong();

    /// notify all waiting IdentClient callbacks
    void notify(const char *result);

    Comm::ConnectionPointer conn;
    MemBuf queryMsg;  ///< the lookup message sent to IDENT server
    IdentClient *clients;
    char buf[IDENT_BUFSIZE];
};

CBDATA_CLASS_INIT(IdentStateData);

// TODO: make these all a series of Async job calls. They are self-contained callbacks now.
static IOCB ReadReply;
static IOCB WriteFeedback;
static CLCB Close;
static CTCB Timeout;
static CNCB ConnectDone;
static hash_table *ident_hash = NULL;
static void ClientAdd(IdentStateData * state, IDCB * callback, void *callback_data);

} // namespace Ident

Ident::IdentConfig Ident::TheConfig;

void
Ident::IdentStateData::deleteThis(const char *)
{
    swanSong();
    delete this;
}

void
Ident::IdentStateData::swanSong()
{
    if (clients != NULL)
        notify(NULL);

    if (Comm::IsConnOpen(conn)) {
        comm_remove_close_handler(conn->fd, Ident::Close, this);
        conn->close();
    }

    hash_remove_link(ident_hash, (hash_link *) this);
    xfree(hash.key);
}

void
Ident::IdentStateData::notify(const char *result)
{
    while (IdentClient *client = clients) {
        void *cbdata;
        clients = client->next;

        if (cbdataReferenceValidDone(client->callback_data, &cbdata))
            client->callback(result, cbdata);

        xfree(client);
    }
}

void
Ident::Close(const CommCloseCbParams &params)
{
    IdentStateData *state = (IdentStateData *)params.data;
    state->deleteThis("connection closed");
}

void
Ident::Timeout(const CommTimeoutCbParams &io)
{
    debugs(30, 3, HERE << io.conn);
    IdentStateData *state = (IdentStateData *)io.data;
    state->deleteThis("timeout");
}

void
Ident::ConnectDone(const Comm::ConnectionPointer &conn, Comm::Flag status, int, void *data)
{
    IdentStateData *state = (IdentStateData *)data;

    if (status != Comm::OK) {
        if (status == Comm::TIMEOUT)
            debugs(30, 3, "IDENT connection timeout to " << state->conn->remote);
        state->deleteThis(status == Comm::TIMEOUT ? "connect timeout" : "connect error");
        return;
    }

    /*
     * see if any of our clients still care
     */
    IdentClient *c;
    for (c = state->clients; c; c = c->next) {
        if (cbdataReferenceValid(c->callback_data))
            break;
    }

    if (c == NULL) {
        state->deleteThis("client(s) aborted");
        return;
    }

    assert(conn != NULL && conn == state->conn);
    comm_add_close_handler(conn->fd, Ident::Close, state);

    AsyncCall::Pointer writeCall = commCbCall(5,4, "Ident::WriteFeedback",
                                   CommIoCbPtrFun(Ident::WriteFeedback, state));
    Comm::Write(conn, &state->queryMsg, writeCall);
    AsyncCall::Pointer readCall = commCbCall(5,4, "Ident::ReadReply",
                                  CommIoCbPtrFun(Ident::ReadReply, state));
    comm_read(conn, state->buf, IDENT_BUFSIZE, readCall);
    AsyncCall::Pointer timeoutCall = commCbCall(5,4, "Ident::Timeout",
                                     CommTimeoutCbPtrFun(Ident::Timeout, state));
    commSetConnTimeout(conn, Ident::TheConfig.timeout, timeoutCall);
}

void
Ident::WriteFeedback(const Comm::ConnectionPointer &conn, char *, size_t len, Comm::Flag flag, int xerrno, void *data)
{
    debugs(30, 5, HERE << conn << ": Wrote IDENT request " << len << " bytes.");

    // TODO handle write errors better. retry or abort?
    if (flag != Comm::OK) {
        debugs(30, 2, HERE << conn << " err-flags=" << flag << " IDENT write error: " << xstrerr(xerrno));
        IdentStateData *state = (IdentStateData *)data;
        state->deleteThis("write error");
    }
}

void
Ident::ReadReply(const Comm::ConnectionPointer &conn, char *buf, size_t len, Comm::Flag flag, int, void *data)
{
    IdentStateData *state = (IdentStateData *)data;
    char *ident = NULL;
    char *t = NULL;

    assert(buf == state->buf);
    assert(conn->fd == state->conn->fd);

    if (flag != Comm::OK || len <= 0) {
        state->deleteThis("read error");
        return;
    }

    /*
     * XXX This isn't really very tolerant. It should read until EOL
     * or EOF and then decode the answer... If the reply is fragmented
     * then this will fail
     */
    buf[len] = '\0';

    if ((t = strchr(buf, '\r')))
        *t = '\0';

    if ((t = strchr(buf, '\n')))
        *t = '\0';

    debugs(30, 5, HERE << conn << ": Read '" << buf << "'");

    if (strstr(buf, "USERID")) {
        if ((ident = strrchr(buf, ':'))) {
            while (xisspace(*++ident));
            if (ident && *ident == '\0')
                ident = NULL;
            state->notify(ident);
        }
    }

    state->deleteThis("completed");
}

void
Ident::ClientAdd(IdentStateData * state, IDCB * callback, void *callback_data)
{
    IdentClient *c = (IdentClient *)xcalloc(1, sizeof(*c));
    IdentClient **C;
    c->callback = callback;
    c->callback_data = cbdataReference(callback_data);

    for (C = &state->clients; *C; C = &(*C)->next);
    *C = c;
}

/*
 * start a TCP connection to the peer host on port 113
 */
void
Ident::Start(const Comm::ConnectionPointer &conn, IDCB * callback, void *data)
{
    IdentStateData *state;
    char key1[IDENT_KEY_SZ];
    char key2[IDENT_KEY_SZ];
    char key[IDENT_KEY_SZ*2+2]; // key1 + ',' + key2 + terminator

    conn->local.toUrl(key1, IDENT_KEY_SZ);
    conn->remote.toUrl(key2, IDENT_KEY_SZ);
    const auto res = snprintf(key, sizeof(key), "%s,%s", key1, key2);
    assert(res > 0);
    assert(static_cast<std::make_unsigned<decltype(res)>::type>(res) < sizeof(key));

    if (!ident_hash) {
        Init();
    }
    if ((state = (IdentStateData *)hash_lookup(ident_hash, key)) != NULL) {
        ClientAdd(state, callback, data);
        return;
    }

    state = new IdentStateData;
    state->hash.key = xstrdup(key);

    // copy the conn details. We do not want the original FD to be re-used by IDENT.
    state->conn = conn->copyDetails();
    // NP: use random port for secure outbound to IDENT_PORT
    state->conn->local.port(0);
    state->conn->remote.port(IDENT_PORT);

    // build our query from the original connection details
    state->queryMsg.init();
    state->queryMsg.appendf("%d, %d\r\n", conn->remote.port(), conn->local.port());

    ClientAdd(state, callback, data);
    hash_join(ident_hash, &state->hash);

    AsyncCall::Pointer call = commCbCall(30,3, "Ident::ConnectDone", CommConnectCbPtrFun(Ident::ConnectDone, state));
    AsyncJob::Start(new Comm::ConnOpener(state->conn, call, Ident::TheConfig.timeout));
}

void
Ident::Init(void)
{
    if (ident_hash) {
        debugs(30, DBG_CRITICAL, "WARNING: Ident already initialized.");
        return;
    }

    ident_hash = hash_create((HASHCMP *) strcmp,
                             hashPrime(Squid_MaxFD / 8),
                             hash4);
}

#endif /* USE_IDENT */

