/* dnode sends a response back to a peer */
static struct msg *
dnode_rsp_send_next(struct context *ctx, struct conn *conn)
{
rstatus_t status;
// SMB: There is some non trivial thing happening here. And I think it is very
// important to read this before anything is changed in here. There is also a
// bug that exists which I will mention briefly:
// A message is a structure that has a list of mbufs which hold the actual data.
// Each mbuf has start, pos, last as pointers (amongst others) which indicate start of the
// buffer, current read position and end of the buffer respectively.
//
// Every time a message is sent to a peer within dynomite, a DNODE header is
// prepended which is created using dmsg_write. A message remembers this case
// in dnode_header_prepended, so that if the messsage is sent in parts, the
// header is not prepended again for the subsequent parts.
//
// Like I said earlier there is a pos pointer in mbuf. If a message is sent
// partially (or it is parsed partially too I think) the pos reflects that
// case such that things can be resumed where it left off.
//
// dmsg_write has a parameter which reflects the payload length following the
// dnode header calculated by msg_length. msg_length is a summation of all
// mbuf sizes (last - start). Which I think is wrong.
//
// +------------+ +---------------+
// | DC1N1 +---------> | DC2N1 |
// +------------+ +-------+-------+
// |
// |
// |
// |
// +-------v-------+
// | DC2N2 |
// +---------------+
//
// Consider the case where
// a node DC1N1 in region DC1 sends a request to DC2N1 which forwards it to
// to local token owner DC2N2. Now DC2N1 receives a response from DC2N2 which
// has to be relayed back to DC1N1. This response from DC2N2 already has a
// dnode header but for the link between DC2N1 and DC2N2. DC2N1 should strip
// this header and prepend its own header for sending it back to DC1N1. This
// gets handled in encryption case since we overwrite all mbufs in the response
// However if the encryption is off, the message length sent to dmsg_write
// consists of the header from DC2N2 also which is wrong. So this relaying
// of responses will not work for the case where encryption is disabled.
//
// So msg_length should really be from mbuf->pos and not mbuf->start. This
// is a problem only with remote region replication since that is the only
// case where we CAN have 2 hops to send the request/response. This is also
// not a problem if encryption is ON.
ASSERT(conn->type == CONN_DNODE_PEER_CLIENT);
struct msg *rsp = rsp_send_next(ctx, conn);
if (rsp != NULL && conn->dyn_mode) {
struct msg *pmsg = rsp->peer;
//need to deal with multi-block later
uint64_t msg_id = pmsg->dmsg->id;
if (rsp->dnode_header_prepended) {
return rsp;
}
struct mbuf *header_buf = mbuf_get();
if (header_buf == NULL) {
loga("Unable to obtain an mbuf for header!");
return NULL; //need to address error here properly
}
dmsg_type_t msg_type = DMSG_RES;
//TODOs: need to set the outcoming conn to be secured too if the incoming conn is secured
if (pmsg->owner->dnode_secured || conn->dnode_secured) {
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VVERB, "Encrypting response ...");
loga("AES encryption key: %s\n", base64_encode(conn->aes_key, AES_KEYLEN));
}
if (ENCRYPTION) {
status = dyn_aes_encrypt_msg(rsp, conn->aes_key);
if (status == DN_ERROR) {
loga("OOM to obtain an mbuf for encryption!");
mbuf_put(header_buf);
req_put(rsp);
return NULL;
}
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "#encrypted bytes : %d", status);
}
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
} else {
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "no encryption on the rsp payload");
}
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
}
} else {
//write dnode header
log_debug(LOG_VERB, "sending dnode response with msg_id %u", msg_id);
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
}
rsp->dnode_header_prepended = 1;
mbuf_insert_head(&rsp->mhdr, header_buf);
if (log_loggable(LOG_VVERB)) {
log_hexdump(LOG_VVERB, header_buf->pos, mbuf_length(header_buf), "resp dyn message - header: ");
msg_dump(rsp);
}
}
return rsp;
}
/* dnode sends a response back to a peer */
struct msg *
dnode_rsp_send_next(struct context *ctx, struct conn *conn)
{
rstatus_t status;
ASSERT(conn->dnode_client && !conn->dnode_server);
struct msg *rsp = rsp_send_next(ctx, conn);
if (rsp != NULL && conn->dyn_mode) {
struct msg *pmsg = rsp->peer;
//need to deal with multi-block later
uint64_t msg_id = pmsg->dmsg->id;
struct mbuf *header_buf = mbuf_get();
if (header_buf == NULL) {
loga("Unable to obtain an mbuf for header!");
return NULL; //need to address error here properly
}
dmsg_type_t msg_type = DMSG_RES;
//TODOs: need to set the outcoming conn to be secured too if the incoming conn is secured
if (pmsg->owner->dnode_secured || conn->dnode_secured) {
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VVERB, "Encrypting response ...");
loga("AES encryption key: %s\n", base64_encode(conn->aes_key, AES_KEYLEN));
}
if (ENCRYPTION) {
status = dyn_aes_encrypt_msg(rsp, conn->aes_key);
if (status == DN_ERROR) {
loga("OOM to obtain an mbuf for encryption!");
mbuf_put(header_buf);
req_put(rsp);
return NULL;
}
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "#encrypted bytes : %d", status);
}
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
} else {
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "no encryption on the rsp payload");
}
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
}
} else {
//write dnode header
log_info("sending dnode response with msg_id %u", msg_id);
dmsg_write(header_buf, msg_id, msg_type, conn, msg_length(rsp));
}
mbuf_insert_head(&rsp->mhdr, header_buf);
if (log_loggable(LOG_VVERB)) {
log_hexdump(LOG_VVERB, header_buf->pos, mbuf_length(header_buf), "resp dyn message - header: ");
msg_dump(rsp);
}
}
return rsp;
}
/* Forward a client request over to a peer */
void dnode_peer_req_forward(struct context *ctx, struct conn *c_conn,
struct conn *p_conn, struct msg *msg,
struct rack *rack, uint8_t *key, uint32_t keylen)
{
struct server *server = p_conn->owner;
log_debug(LOG_DEBUG, "forwarding request from client conn '%s' to peer conn '%s' on rack '%.*s' dc '%.*s' ",
dn_unresolve_peer_desc(c_conn->sd), dn_unresolve_peer_desc(p_conn->sd),
rack->name->len, rack->name->data,
server->dc.len, server->dc.data);
struct string *dc = rack->dc;
rstatus_t status;
/* enqueue message (request) into client outq, if response is expected */
if (!msg->noreply && !msg->swallow) {
conn_enqueue_outq(ctx, c_conn, msg);
}
ASSERT(p_conn->type == CONN_DNODE_PEER_SERVER);
ASSERT((c_conn->type == CONN_CLIENT) ||
(c_conn->type == CONN_DNODE_PEER_CLIENT));
/* enqueue the message (request) into peer inq */
status = event_add_out(ctx->evb, p_conn);
if (status != DN_OK) {
dnode_req_forward_error(ctx, p_conn, msg);
p_conn->err = errno;
return;
}
struct mbuf *header_buf = mbuf_get();
if (header_buf == NULL) {
loga("Unable to obtain an mbuf for dnode msg's header!");
req_put(msg);
return;
}
struct server_pool *pool = c_conn->owner;
dmsg_type_t msg_type = (string_compare(&pool->dc, dc) != 0)? DMSG_REQ_FORWARD : DMSG_REQ;
if (p_conn->dnode_secured) {
//Encrypting and adding header for a request
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "AES encryption key: %s\n", base64_encode(p_conn->aes_key, AES_KEYLEN));
}
//write dnode header
if (ENCRYPTION) {
status = dyn_aes_encrypt_msg(msg, p_conn->aes_key);
if (status == DN_ERROR) {
loga("OOM to obtain an mbuf for encryption!");
mbuf_put(header_buf);
req_put(msg);
return;
}
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "#encrypted bytes : %d", status);
}
dmsg_write(header_buf, msg->id, msg_type, p_conn, msg_length(msg));
} else {
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VERB, "no encryption on the msg payload");
}
dmsg_write(header_buf, msg->id, msg_type, p_conn, msg_length(msg));
}
} else {
//write dnode header
dmsg_write(header_buf, msg->id, msg_type, p_conn, msg_length(msg));
}
mbuf_insert_head(&msg->mhdr, header_buf);
if (log_loggable(LOG_VVERB)) {
log_hexdump(LOG_VVERB, header_buf->pos, mbuf_length(header_buf), "dyn message header: ");
msg_dump(msg);
}
conn_enqueue_inq(ctx, p_conn, msg);
dnode_peer_req_forward_stats(ctx, p_conn->owner, msg);
if (log_loggable(LOG_VVERB)) {
log_debug(LOG_VVERB, "remote forward from c %d to s %d req %"PRIu64" len %"PRIu32
" type %d with key '%.*s'", c_conn->sd, p_conn->sd, msg->id,
msg->mlen, msg->type, keylen, key);
}
}
