Function clusterProcessPacket

app/redis-6.2.6/src/cluster.c:1752–2241

When this function is called, there is a packet to process starting * at node->rcvbuf. Releasing the buffer is up to the caller, so this * function should just handle the higher level stuff of processing the * packet, modifying the cluster state if needed. * * The function returns 1 if the link is still valid after the packet * was processed, otherwise 0 if the link was freed since the packe

 * processing lead to some inconsistency error (for instance a PONG
 * received from the wrong sender ID). */
int clusterProcessPacket(clusterLink *link) {
    clusterMsg *hdr = (clusterMsg*) link->rcvbuf;
    uint32_t totlen = ntohl(hdr->totlen);
    uint16_t type = ntohs(hdr->type);
    mstime_t now = mstime();

    if (type < CLUSTERMSG_TYPE_COUNT)
        server.cluster->stats_bus_messages_received[type]++;
    serverLog(LL_DEBUG,"--- Processing packet of type %d, %lu bytes",
        type, (unsigned long) totlen);

    /* Perform sanity checks */
    if (totlen < 16) return 1; /* At least signature, version, totlen, count. */
    if (totlen > link->rcvbuf_len) return 1;

    if (ntohs(hdr->ver) != CLUSTER_PROTO_VER) {
        /* Can't handle messages of different versions. */
        return 1;
    }

    uint16_t flags = ntohs(hdr->flags);
    uint64_t senderCurrentEpoch = 0, senderConfigEpoch = 0;
    clusterNode *sender;

    if (type == CLUSTERMSG_TYPE_PING || type == CLUSTERMSG_TYPE_PONG ||
        type == CLUSTERMSG_TYPE_MEET)
    {
        uint16_t count = ntohs(hdr->count);
        uint32_t explen; /* expected length of this packet */

        explen = sizeof(clusterMsg)-sizeof(union clusterMsgData);
        explen += (sizeof(clusterMsgDataGossip)*count);
        if (totlen != explen) return 1;
    } else if (type == CLUSTERMSG_TYPE_FAIL) {
        uint32_t explen = sizeof(clusterMsg)-sizeof(union clusterMsgData);

        explen += sizeof(clusterMsgDataFail);
        if (totlen != explen) return 1;
    } else if (type == CLUSTERMSG_TYPE_PUBLISH) {
        uint32_t explen = sizeof(clusterMsg)-sizeof(union clusterMsgData);

        explen += sizeof(clusterMsgDataPublish) -
                8 +
                ntohl(hdr->data.publish.msg.channel_len) +
                ntohl(hdr->data.publish.msg.message_len);
        if (totlen != explen) return 1;
    } else if (type == CLUSTERMSG_TYPE_FAILOVER_AUTH_REQUEST ||
               type == CLUSTERMSG_TYPE_FAILOVER_AUTH_ACK ||
               type == CLUSTERMSG_TYPE_MFSTART)
    {
        uint32_t explen = sizeof(clusterMsg)-sizeof(union clusterMsgData);

        if (totlen != explen) return 1;
    } else if (type == CLUSTERMSG_TYPE_UPDATE) {
        uint32_t explen = sizeof(clusterMsg)-sizeof(union clusterMsgData);

        explen += sizeof(clusterMsgDataUpdate);
        if (totlen != explen) return 1;