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mqtt: improve the state machine
To handle PUBLISH before SUBACK and more. Updated the existing tests and added three new ones. Reported-by: Christoph Krey Bug: https://curl.haxx.se/mail/lib-2020-04/0021.html Closes #5246
This commit is contained in:
Daniel Stenberg
parent
d1a2816b41
commit
5811beba39
11 changed files with 402 additions and 99 deletions
180
lib/mqtt.c
180
lib/mqtt.c
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@ -51,8 +51,8 @@
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#define MQTT_MSG_SUBACK 0x90
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#define MQTT_MSG_DISCONNECT 0xe0
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#define MQTT_CONNACK_LEN 4
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#define MQTT_SUBACK_LEN 5
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#define MQTT_CONNACK_LEN 2
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#define MQTT_SUBACK_LEN 3
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#define MQTT_CLIENTID_LEN 12 /* "curl0123abcd" */
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/*
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@ -194,13 +194,9 @@ static CURLcode mqtt_verify_connack(struct connectdata *conn)
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}
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/* verify CONNACK */
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if(readbuf[0] != MQTT_MSG_CONNACK ||
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readbuf[1] != 0x02 ||
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readbuf[2] != 0x00 ||
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readbuf[3] != 0x00) {
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failf(data, "Expected %02x%02x%02x%02x but got %02x%02x%02x%02x",
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MQTT_MSG_CONNACK, 0x02, 0x00, 0x00,
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readbuf[0], readbuf[1], readbuf[2], readbuf[3]);
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if(readbuf[0] != 0x00 || readbuf[1] != 0x00) {
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failf(data, "Expected %02x%02x but got %02x%02x",
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0x00, 0x00, readbuf[0], readbuf[1]);
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result = CURLE_WEIRD_SERVER_REPLY;
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}
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@ -285,6 +281,9 @@ fail:
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return result;
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}
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/*
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* Called when the first byte was already read.
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*/
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static CURLcode mqtt_verify_suback(struct connectdata *conn)
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{
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CURLcode result;
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@ -307,11 +306,9 @@ static CURLcode mqtt_verify_suback(struct connectdata *conn)
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}
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/* verify SUBACK */
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if(readbuf[0] != MQTT_MSG_SUBACK ||
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readbuf[1] != 0x03 ||
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readbuf[2] != ((mqtt->packetid >> 8) & 0xff) ||
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readbuf[3] != (mqtt->packetid & 0xff) ||
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readbuf[4] != 0x00)
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if(readbuf[0] != ((mqtt->packetid >> 8) & 0xff) ||
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readbuf[1] != (mqtt->packetid & 0xff) ||
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readbuf[2] != 0x00)
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result = CURLE_WEIRD_SERVER_REPLY;
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fail:
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@ -377,67 +374,97 @@ static size_t mqtt_decode_len(unsigned char *buf,
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mult *= 128;
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}
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*lenbytes = i;
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if(lenbytes)
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*lenbytes = i;
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return len;
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}
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#ifdef CURLDEBUG
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static const char *statenames[]={
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"MQTT_FIRST",
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"MQTT_REMAINING_LENGTH",
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"MQTT_CONNACK",
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"MQTT_SUBACK",
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"MQTT_SUBACK_COMING",
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"MQTT_PUBWAIT",
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"MQTT_PUB_REMAIN"
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};
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#endif
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/* The only way to change state */
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static void mqstate(struct connectdata *conn,
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enum mqttstate state,
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enum mqttstate nextstate) /* used if state == FIRST */
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{
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struct mqtt_conn *mqtt = &conn->proto.mqtt;
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#ifdef CURLDEBUG
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infof(conn->data, "%s (from %s) (next is %s)\n",
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statenames[state],
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statenames[mqtt->state],
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(state == MQTT_FIRST)? statenames[nextstate] : "");
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#endif
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mqtt->state = state;
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if(state == MQTT_FIRST)
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mqtt->nextstate = nextstate;
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}
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/* for the publish packet */
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#define MQTT_HEADER_LEN 5 /* max 5 bytes */
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static CURLcode mqtt_read_publish(struct connectdata *conn,
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bool *done)
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{
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CURLcode result;
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CURLcode result = CURLE_OK;
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curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
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ssize_t nread;
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struct Curl_easy *data = conn->data;
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unsigned char *pkt = (unsigned char *)data->state.buffer;
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size_t remlen, lenbytes;
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size_t remlen;
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struct mqtt_conn *mqtt = &conn->proto.mqtt;
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struct MQTT *mq = data->req.protop;
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unsigned char packet;
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switch(mqtt->state) {
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case MQTT_SUBWAIT:
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/* Read the initial byte and the entire Remaining Length field
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in this state */
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result = Curl_read(conn, sockfd, (char *)&pkt[mq->npacket], 1, &nread);
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MQTT_SUBACK_COMING:
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case MQTT_SUBACK_COMING:
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result = mqtt_verify_suback(conn);
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if(result)
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break;
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mqstate(conn, MQTT_FIRST, MQTT_PUBWAIT);
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break;
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case MQTT_SUBACK:
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case MQTT_PUBWAIT:
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/* we are expecting PUBLISH or SUBACK */
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packet = mq->firstbyte & 0xf0;
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if(packet == MQTT_MSG_PUBLISH)
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mqstate(conn, MQTT_PUB_REMAIN, MQTT_NOSTATE);
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else if(packet == MQTT_MSG_SUBACK) {
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mqstate(conn, MQTT_SUBACK_COMING, MQTT_NOSTATE);
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goto MQTT_SUBACK_COMING;
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}
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else if(packet == MQTT_MSG_DISCONNECT) {
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infof(data, "Got DISCONNECT\n");
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*done = TRUE;
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goto end;
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if(data->set.verbose)
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Curl_debug(data, CURLINFO_HEADER_IN, (char *)&pkt[mq->npacket], 1);
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/* we are expecting a PUBLISH message */
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if(!mq->npacket && ((pkt[0] & 0xf0) != MQTT_MSG_PUBLISH)) {
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if(pkt[0] == MQTT_MSG_DISCONNECT) {
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infof(data, "Got DISCONNECT\n");
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*done = TRUE;
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goto end;
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}
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}
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else {
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result = CURLE_WEIRD_SERVER_REPLY;
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goto end;
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}
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else if((mq->npacket >= 1) && !(pkt[mq->npacket] & 0x80))
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/* as long as the high bit is set in the length byte, we read one more
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byte, then get the remainder of the PUBLISH */
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mqtt->state = MQTT_SUB_REMAIN;
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mq->npacket++;
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if(mqtt->state == MQTT_SUBWAIT)
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return result;
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/* -- switched state -- */
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/* remember the first byte */
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mq->firstbyte = pkt[0];
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remlen = mqtt_decode_len(&pkt[1], 4, &lenbytes);
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remlen = mq->remaining_length;
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infof(data, "Remaining length: %zd bytes\n", remlen);
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Curl_pgrsSetDownloadSize(data, remlen);
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data->req.bytecount = 0;
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data->req.size = remlen;
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mq->npacket = remlen; /* get this many bytes */
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/* FALLTHROUGH */
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case MQTT_SUB_REMAIN: {
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case MQTT_PUB_REMAIN: {
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/* read rest of packet, but no more. Cap to buffer size */
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struct SingleRequest *k = &data->req;
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size_t rest = mq->npacket;
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@ -450,6 +477,11 @@ static CURLcode mqtt_read_publish(struct connectdata *conn,
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}
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goto end;
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}
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if(!nread) {
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infof(data, "server disconnected\n");
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result = CURLE_PARTIAL_FILE;
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goto end;
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}
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if(data->set.verbose)
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Curl_debug(data, CURLINFO_DATA_IN, (char *)pkt, (size_t)nread);
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@ -465,7 +497,7 @@ static CURLcode mqtt_read_publish(struct connectdata *conn,
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if(!mq->npacket)
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/* no more PUBLISH payload, back to subscribe wait state */
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mqtt->state = MQTT_SUBWAIT;
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mqstate(conn, MQTT_FIRST, MQTT_PUBWAIT);
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break;
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}
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default:
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@ -481,7 +513,6 @@ static CURLcode mqtt_do(struct connectdata *conn, bool *done)
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{
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CURLcode result = CURLE_OK;
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struct Curl_easy *data = conn->data;
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struct mqtt_conn *mqtt = &conn->proto.mqtt;
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*done = FALSE; /* unconditionally */
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@ -490,7 +521,7 @@ static CURLcode mqtt_do(struct connectdata *conn, bool *done)
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failf(data, "Error %d sending MQTT CONN request", result);
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return result;
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}
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mqtt->state = MQTT_CONNACK;
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mqstate(conn, MQTT_FIRST, MQTT_CONNACK);
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return CURLE_OK;
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}
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@ -500,6 +531,10 @@ static CURLcode mqtt_doing(struct connectdata *conn, bool *done)
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struct mqtt_conn *mqtt = &conn->proto.mqtt;
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struct Curl_easy *data = conn->data;
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struct MQTT *mq = data->req.protop;
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ssize_t nread;
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curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
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unsigned char *pkt = (unsigned char *)data->state.buffer;
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unsigned char byte;
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*done = FALSE;
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@ -512,7 +547,41 @@ static CURLcode mqtt_doing(struct connectdata *conn, bool *done)
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return result;
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}
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infof(data, "mqtt_doing: state [%d]\n", (int) mqtt->state);
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switch(mqtt->state) {
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case MQTT_FIRST:
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/* Read the initial byte only */
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result = Curl_read(conn, sockfd, (char *)&mq->firstbyte, 1, &nread);
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if(result)
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break;
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if(data->set.verbose)
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Curl_debug(data, CURLINFO_HEADER_IN, (char *)&mq->firstbyte, 1);
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/* remember the first byte */
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mq->npacket = 0;
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mqstate(conn, MQTT_REMAINING_LENGTH, MQTT_NOSTATE);
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/* FALLTHROUGH */
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case MQTT_REMAINING_LENGTH:
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do {
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result = Curl_read(conn, sockfd, (char *)&byte, 1, &nread);
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if(result)
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break;
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if(data->set.verbose)
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Curl_debug(data, CURLINFO_HEADER_IN, (char *)&byte, 1);
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pkt[mq->npacket++] = byte;
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} while((byte & 0x80) && (mq->npacket < 4));
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mq->remaining_length = mqtt_decode_len(&pkt[0], mq->npacket, NULL);
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mq->npacket = 0;
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if(mq->remaining_length) {
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mqstate(conn, mqtt->nextstate, MQTT_NOSTATE);
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break;
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}
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mqstate(conn, MQTT_FIRST, MQTT_FIRST);
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if(mq->firstbyte == MQTT_MSG_DISCONNECT) {
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infof(data, "Got DISCONNECT\n");
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*done = TRUE;
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}
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break;
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case MQTT_CONNACK:
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result = mqtt_verify_connack(conn);
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if(result)
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@ -524,24 +593,19 @@ static CURLcode mqtt_doing(struct connectdata *conn, bool *done)
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result = mqtt_disconnect(conn);
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*done = TRUE;
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}
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mqtt->nextstate = MQTT_FIRST;
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}
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else {
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result = mqtt_subscribe(conn);
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if(!result)
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mqtt->state = MQTT_SUBACK;
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if(!result) {
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mqstate(conn, MQTT_FIRST, MQTT_SUBACK);
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}
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}
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break;
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case MQTT_SUBACK:
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result = mqtt_verify_suback(conn);
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if(result)
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break;
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mqtt->state = MQTT_SUBWAIT;
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break;
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case MQTT_SUBWAIT:
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case MQTT_SUB_REMAIN:
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case MQTT_PUBWAIT:
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case MQTT_PUB_REMAIN:
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result = mqtt_read_publish(conn, done);
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if(result)
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break;
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24
lib/mqtt.h
24
lib/mqtt.h
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@ -26,13 +26,22 @@
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extern const struct Curl_handler Curl_handler_mqtt;
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#endif
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enum mqttstate {
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MQTT_FIRST, /* 0 */
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MQTT_REMAINING_LENGTH, /* 1 */
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MQTT_CONNACK, /* 2 */
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MQTT_SUBACK, /* 3 */
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MQTT_SUBACK_COMING, /* 4 - the SUBACK remainder */
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MQTT_PUBWAIT, /* 5 - wait for publish */
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MQTT_PUB_REMAIN, /* 6 - wait for the remainder of the publish */
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MQTT_NOSTATE = 99 /* never an actual state */
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};
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struct mqtt_conn {
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enum {
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MQTT_CONNACK,
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MQTT_SUBACK,
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MQTT_SUBWAIT, /* wait for subscribe response */
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MQTT_SUB_REMAIN /* wait for the remainder of the subscribe response */
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} state;
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enum mqttstate state;
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enum mqttstate nextstate; /* switch to this after remaining length is
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done */
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unsigned int packetid;
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};
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@ -41,9 +50,10 @@ struct MQTT {
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char *sendleftovers;
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size_t nsend; /* size of sendleftovers */
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/* when receving a PUBLISH */
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/* when receving */
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size_t npacket; /* byte counter */
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unsigned char firstbyte;
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size_t remaining_length;
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};
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#endif /* HEADER_CURL_MQTT_H */
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