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curl/lib/mqtt.c
Daniel Stenberg 215db086e0
lib: pass in 'struct Curl_easy *' to most functions 
... in most cases instead of 'struct connectdata *' but in some cases in
addition to.

- We mostly operate on transfers and not connections.

- We need the transfer handle to log, store data and more. Everything in
  libcurl is driven by a transfer (the CURL * in the public API).

- This work clarifies and separates the transfers from the connections
  better.

- We should avoid "conn->data". Since individual connections can be used
  by many transfers when multiplexing, making sure that conn->data
  points to the current and correct transfer at all times is difficult
  and has been notoriously error-prone over the years. The goal is to
  ultimately remove the conn->data pointer for this reason.

Closes #6425
2021-01-17 23:56:09 +01:00

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2020 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
* Copyright (C) 2019, Björn Stenberg, <bjorn@haxx.se>
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
#include "curl_setup.h"
#ifndef CURL_DISABLE_MQTT
#include "urldata.h"
#include <curl/curl.h>
#include "transfer.h"
#include "sendf.h"
#include "progress.h"
#include "mqtt.h"
#include "select.h"
#include "strdup.h"
#include "url.h"
#include "escape.h"
#include "warnless.h"
#include "curl_printf.h"
#include "curl_memory.h"
#include "multiif.h"
#include "rand.h"
/* The last #include file should be: */
#include "memdebug.h"
#define MQTT_MSG_CONNECT 0x10
#define MQTT_MSG_CONNACK 0x20
#define MQTT_MSG_PUBLISH 0x30
#define MQTT_MSG_SUBSCRIBE 0x82
#define MQTT_MSG_SUBACK 0x90
#define MQTT_MSG_DISCONNECT 0xe0
#define MQTT_CONNACK_LEN 2
#define MQTT_SUBACK_LEN 3
#define MQTT_CLIENTID_LEN 12 /* "curl0123abcd" */
/*
* Forward declarations.
*/
static CURLcode mqtt_do(struct Curl_easy *data, bool *done);
static CURLcode mqtt_doing(struct Curl_easy *data, bool *done);
static int mqtt_getsock(struct Curl_easy *data, struct connectdata *conn,
curl_socket_t *sock);
static CURLcode mqtt_setup_conn(struct Curl_easy *data,
struct connectdata *conn);
/*
* MQTT protocol handler.
*/
const struct Curl_handler Curl_handler_mqtt = {
"MQTT", /* scheme */
mqtt_setup_conn, /* setup_connection */
mqtt_do, /* do_it */
ZERO_NULL, /* done */
ZERO_NULL, /* do_more */
ZERO_NULL, /* connect_it */
ZERO_NULL, /* connecting */
mqtt_doing, /* doing */
ZERO_NULL, /* proto_getsock */
mqtt_getsock, /* doing_getsock */
ZERO_NULL, /* domore_getsock */
ZERO_NULL, /* perform_getsock */
ZERO_NULL, /* disconnect */
ZERO_NULL, /* readwrite */
ZERO_NULL, /* connection_check */
PORT_MQTT, /* defport */
CURLPROTO_MQTT, /* protocol */
CURLPROTO_MQTT, /* family */
PROTOPT_NONE /* flags */
};
static CURLcode mqtt_setup_conn(struct Curl_easy *data,
struct connectdata *conn)
{
/* allocate the HTTP-specific struct for the Curl_easy, only to survive
during this request */
struct MQTT *mq;
(void)conn;
DEBUGASSERT(data->req.p.mqtt == NULL);
mq = calloc(1, sizeof(struct MQTT));
if(!mq)
return CURLE_OUT_OF_MEMORY;
data->req.p.mqtt = mq;
return CURLE_OK;
}
static CURLcode mqtt_send(struct Curl_easy *data,
char *buf, size_t len)
{
CURLcode result = CURLE_OK;
struct connectdata *conn = data->conn;
curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
struct MQTT *mq = data->req.p.mqtt;
ssize_t n;
result = Curl_write(data, sockfd, buf, len, &n);
if(!result)
Curl_debug(data, CURLINFO_HEADER_OUT, buf, (size_t)n);
if(len != (size_t)n) {
size_t nsend = len - n;
char *sendleftovers = Curl_memdup(&buf[n], nsend);
if(!sendleftovers)
return CURLE_OUT_OF_MEMORY;
mq->sendleftovers = sendleftovers;
mq->nsend = nsend;
}
return result;
}
/* Generic function called by the multi interface to figure out what socket(s)
to wait for and for what actions during the DOING and PROTOCONNECT
states */
static int mqtt_getsock(struct Curl_easy *data,
struct connectdata *conn,
curl_socket_t *sock)
{
(void)data;
sock[0] = conn->sock[FIRSTSOCKET];
return GETSOCK_READSOCK(FIRSTSOCKET);
}
static CURLcode mqtt_connect(struct Curl_easy *data)
{
CURLcode result = CURLE_OK;
const size_t client_id_offset = 14;
const size_t packetlen = client_id_offset + MQTT_CLIENTID_LEN;
char client_id[MQTT_CLIENTID_LEN + 1] = "curl";
const size_t clen = strlen("curl");
char packet[32] = {
MQTT_MSG_CONNECT, /* packet type */
0x00, /* remaining length */
0x00, 0x04, /* protocol length */
'M','Q','T','T', /* protocol name */
0x04, /* protocol level */
0x02, /* CONNECT flag: CleanSession */
0x00, 0x3c, /* keep-alive 0 = disabled */
0x00, 0x00 /* payload1 length */
};
packet[1] = (packetlen - 2) & 0x7f;
packet[client_id_offset - 1] = MQTT_CLIENTID_LEN;
result = Curl_rand_hex(data, (unsigned char *)&client_id[clen],
MQTT_CLIENTID_LEN - clen + 1);
memcpy(&packet[client_id_offset], client_id, MQTT_CLIENTID_LEN);
infof(data, "Using client id '%s'\n", client_id);
if(!result)
result = mqtt_send(data, packet, packetlen);
return result;
}
static CURLcode mqtt_disconnect(struct Curl_easy *data)
{
CURLcode result = CURLE_OK;
result = mqtt_send(data, (char *)"\xe0\x00", 2);
return result;
}
static CURLcode mqtt_verify_connack(struct Curl_easy *data)
{
CURLcode result;
struct connectdata *conn = data->conn;
curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
unsigned char readbuf[MQTT_CONNACK_LEN];
ssize_t nread;
result = Curl_read(data, sockfd, (char *)readbuf, MQTT_CONNACK_LEN, &nread);
if(result)
goto fail;
Curl_debug(data, CURLINFO_HEADER_IN, (char *)readbuf, (size_t)nread);
/* fixme */
if(nread < MQTT_CONNACK_LEN) {
result = CURLE_WEIRD_SERVER_REPLY;
goto fail;
}
/* verify CONNACK */
if(readbuf[0] != 0x00 || readbuf[1] != 0x00) {
failf(data, "Expected %02x%02x but got %02x%02x",
0x00, 0x00, readbuf[0], readbuf[1]);
result = CURLE_WEIRD_SERVER_REPLY;
}
fail:
return result;
}
static CURLcode mqtt_get_topic(struct Curl_easy *data,
char **topic, size_t *topiclen)
{
CURLcode result = CURLE_OK;
char *path = data->state.up.path;
if(strlen(path) > 1) {
result = Curl_urldecode(data, path + 1, 0, topic, topiclen,
REJECT_NADA);
}
else {
failf(data, "Error: No topic specified.");
result = CURLE_URL_MALFORMAT;
}
return result;
}
static int mqtt_encode_len(char *buf, size_t len)
{
unsigned char encoded;
int i;
for(i = 0; (len > 0) && (i<4); i++) {
encoded = len % 0x80;
len /= 0x80;
if(len)
encoded |= 0x80;
buf[i] = encoded;
}
return i;
}
static CURLcode mqtt_subscribe(struct Curl_easy *data)
{
CURLcode result = CURLE_OK;
char *topic = NULL;
size_t topiclen;
unsigned char *packet = NULL;
size_t packetlen;
char encodedsize[4];
size_t n;
struct connectdata *conn = data->conn;
result = mqtt_get_topic(data, &topic, &topiclen);
if(result)
goto fail;
conn->proto.mqtt.packetid++;
packetlen = topiclen + 5; /* packetid + topic (has a two byte length field)
+ 2 bytes topic length + QoS byte */
n = mqtt_encode_len((char *)encodedsize, packetlen);
packetlen += n + 1; /* add one for the control packet type byte */
packet = malloc(packetlen);
if(!packet) {
result = CURLE_OUT_OF_MEMORY;
goto fail;
}
packet[0] = MQTT_MSG_SUBSCRIBE;
memcpy(&packet[1], encodedsize, n);
packet[1 + n] = (conn->proto.mqtt.packetid >> 8) & 0xff;
packet[2 + n] = conn->proto.mqtt.packetid & 0xff;
packet[3 + n] = (topiclen >> 8) & 0xff;
packet[4 + n ] = topiclen & 0xff;
memcpy(&packet[5 + n], topic, topiclen);
packet[5 + n + topiclen] = 0; /* QoS zero */
result = mqtt_send(data, (char *)packet, packetlen);
fail:
free(topic);
free(packet);
return result;
}
/*
* Called when the first byte was already read.
*/
static CURLcode mqtt_verify_suback(struct Curl_easy *data)
{
CURLcode result;
struct connectdata *conn = data->conn;
curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
unsigned char readbuf[MQTT_SUBACK_LEN];
ssize_t nread;
struct mqtt_conn *mqtt = &conn->proto.mqtt;
result = Curl_read(data, sockfd, (char *)readbuf, MQTT_SUBACK_LEN, &nread);
if(result)
goto fail;
Curl_debug(data, CURLINFO_HEADER_IN, (char *)readbuf, (size_t)nread);
/* fixme */
if(nread < MQTT_SUBACK_LEN) {
result = CURLE_WEIRD_SERVER_REPLY;
goto fail;
}
/* verify SUBACK */
if(readbuf[0] != ((mqtt->packetid >> 8) & 0xff) ||
readbuf[1] != (mqtt->packetid & 0xff) ||
readbuf[2] != 0x00)
result = CURLE_WEIRD_SERVER_REPLY;
fail:
return result;
}
static CURLcode mqtt_publish(struct Curl_easy *data)
{
CURLcode result;
char *payload = data->set.postfields;
size_t payloadlen;
char *topic = NULL;
size_t topiclen;
unsigned char *pkt = NULL;
size_t i = 0;
size_t remaininglength;
size_t encodelen;
char encodedbytes[4];
curl_off_t postfieldsize = data->set.postfieldsize;
if(!payload)
return CURLE_BAD_FUNCTION_ARGUMENT;
if(postfieldsize < 0)
payloadlen = strlen(payload);
else
payloadlen = (size_t)postfieldsize;
result = mqtt_get_topic(data, &topic, &topiclen);
if(result)
goto fail;
remaininglength = payloadlen + 2 + topiclen;
encodelen = mqtt_encode_len(encodedbytes, remaininglength);
/* add the control byte and the encoded remaining length */
pkt = malloc(remaininglength + 1 + encodelen);
if(!pkt) {
result = CURLE_OUT_OF_MEMORY;
goto fail;
}
/* assemble packet */
pkt[i++] = MQTT_MSG_PUBLISH;
memcpy(&pkt[i], encodedbytes, encodelen);
i += encodelen;
pkt[i++] = (topiclen >> 8) & 0xff;
pkt[i++] = (topiclen & 0xff);
memcpy(&pkt[i], topic, topiclen);
i += topiclen;
memcpy(&pkt[i], payload, payloadlen);
i += payloadlen;
result = mqtt_send(data, (char *)pkt, i);
fail:
free(pkt);
free(topic);
return result;
}
static size_t mqtt_decode_len(unsigned char *buf,
size_t buflen, size_t *lenbytes)
{
size_t len = 0;
size_t mult = 1;
size_t i;
unsigned char encoded = 128;
for(i = 0; (i < buflen) && (encoded & 128); i++) {
encoded = buf[i];
len += (encoded & 127) * mult;
mult *= 128;
}
if(lenbytes)
*lenbytes = i;
return len;
}
#ifdef CURLDEBUG
static const char *statenames[]={
"MQTT_FIRST",
"MQTT_REMAINING_LENGTH",
"MQTT_CONNACK",
"MQTT_SUBACK",
"MQTT_SUBACK_COMING",
"MQTT_PUBWAIT",
"MQTT_PUB_REMAIN",
"NOT A STATE"
};
#endif
/* The only way to change state */
static void mqstate(struct Curl_easy *data,
enum mqttstate state,
enum mqttstate nextstate) /* used if state == FIRST */
{
struct connectdata *conn = data->conn;
struct mqtt_conn *mqtt = &conn->proto.mqtt;
#ifdef CURLDEBUG
infof(data, "%s (from %s) (next is %s)\n",
statenames[state],
statenames[mqtt->state],
(state == MQTT_FIRST)? statenames[nextstate] : "");
#endif
mqtt->state = state;
if(state == MQTT_FIRST)
mqtt->nextstate = nextstate;
}
/* for the publish packet */
#define MQTT_HEADER_LEN 5 /* max 5 bytes */
static CURLcode mqtt_read_publish(struct Curl_easy *data, bool *done)
{
CURLcode result = CURLE_OK;
struct connectdata *conn = data->conn;
curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
ssize_t nread;
unsigned char *pkt = (unsigned char *)data->state.buffer;
size_t remlen;
struct mqtt_conn *mqtt = &conn->proto.mqtt;
struct MQTT *mq = data->req.p.mqtt;
unsigned char packet;
switch(mqtt->state) {
MQTT_SUBACK_COMING:
case MQTT_SUBACK_COMING:
result = mqtt_verify_suback(data);
if(result)
break;
mqstate(data, MQTT_FIRST, MQTT_PUBWAIT);
break;
case MQTT_SUBACK:
case MQTT_PUBWAIT:
/* we are expecting PUBLISH or SUBACK */
packet = mq->firstbyte & 0xf0;
if(packet == MQTT_MSG_PUBLISH)
mqstate(data, MQTT_PUB_REMAIN, MQTT_NOSTATE);
else if(packet == MQTT_MSG_SUBACK) {
mqstate(data, MQTT_SUBACK_COMING, MQTT_NOSTATE);
goto MQTT_SUBACK_COMING;
}
else if(packet == MQTT_MSG_DISCONNECT) {
infof(data, "Got DISCONNECT\n");
*done = TRUE;
goto end;
}
else {
result = CURLE_WEIRD_SERVER_REPLY;
goto end;
}
/* -- switched state -- */
remlen = mq->remaining_length;
infof(data, "Remaining length: %zd bytes\n", remlen);
Curl_pgrsSetDownloadSize(data, remlen);
data->req.bytecount = 0;
data->req.size = remlen;
mq->npacket = remlen; /* get this many bytes */
/* FALLTHROUGH */
case MQTT_PUB_REMAIN: {
/* read rest of packet, but no more. Cap to buffer size */
struct SingleRequest *k = &data->req;
size_t rest = mq->npacket;
if(rest > (size_t)data->set.buffer_size)
rest = (size_t)data->set.buffer_size;
result = Curl_read(data, sockfd, (char *)pkt, rest, &nread);
if(result) {
if(CURLE_AGAIN == result) {
infof(data, "EEEE AAAAGAIN\n");
}
goto end;
}
if(!nread) {
infof(data, "server disconnected\n");
result = CURLE_PARTIAL_FILE;
goto end;
}
Curl_debug(data, CURLINFO_DATA_IN, (char *)pkt, (size_t)nread);
mq->npacket -= nread;
k->bytecount += nread;
Curl_pgrsSetDownloadCounter(data, k->bytecount);
/* if QoS is set, message contains packet id */
result = Curl_client_write(data, CLIENTWRITE_BODY, (char *)pkt, nread);
if(result)
goto end;
if(!mq->npacket)
/* no more PUBLISH payload, back to subscribe wait state */
mqstate(data, MQTT_FIRST, MQTT_PUBWAIT);
break;
}
default:
DEBUGASSERT(NULL); /* illegal state */
result = CURLE_WEIRD_SERVER_REPLY;
goto end;
}
end:
return result;
}
static CURLcode mqtt_do(struct Curl_easy *data, bool *done)
{
CURLcode result = CURLE_OK;
*done = FALSE; /* unconditionally */
result = mqtt_connect(data);
if(result) {
failf(data, "Error %d sending MQTT CONN request", result);
return result;
}
mqstate(data, MQTT_FIRST, MQTT_CONNACK);
return CURLE_OK;
}
static CURLcode mqtt_doing(struct Curl_easy *data, bool *done)
{
CURLcode result = CURLE_OK;
struct connectdata *conn = data->conn;
struct mqtt_conn *mqtt = &conn->proto.mqtt;
struct MQTT *mq = data->req.p.mqtt;
ssize_t nread;
curl_socket_t sockfd = conn->sock[FIRSTSOCKET];
unsigned char *pkt = (unsigned char *)data->state.buffer;
unsigned char byte;
*done = FALSE;
if(mq->nsend) {
/* send the remainder of an outgoing packet */
char *ptr = mq->sendleftovers;
result = mqtt_send(data, mq->sendleftovers, mq->nsend);
free(ptr);
if(result)
return result;
}
infof(data, "mqtt_doing: state [%d]\n", (int) mqtt->state);
switch(mqtt->state) {
case MQTT_FIRST:
/* Read the initial byte only */
result = Curl_read(data, sockfd, (char *)&mq->firstbyte, 1, &nread);
if(!nread)
break;
Curl_debug(data, CURLINFO_HEADER_IN, (char *)&mq->firstbyte, 1);
/* remember the first byte */
mq->npacket = 0;
mqstate(data, MQTT_REMAINING_LENGTH, MQTT_NOSTATE);
/* FALLTHROUGH */
case MQTT_REMAINING_LENGTH:
do {
result = Curl_read(data, sockfd, (char *)&byte, 1, &nread);
if(!nread)
break;
Curl_debug(data, CURLINFO_HEADER_IN, (char *)&byte, 1);
pkt[mq->npacket++] = byte;
} while((byte & 0x80) && (mq->npacket < 4));
if(result)
break;
mq->remaining_length = mqtt_decode_len(&pkt[0], mq->npacket, NULL);
mq->npacket = 0;
if(mq->remaining_length) {
mqstate(data, mqtt->nextstate, MQTT_NOSTATE);
break;
}
mqstate(data, MQTT_FIRST, MQTT_FIRST);
if(mq->firstbyte == MQTT_MSG_DISCONNECT) {
infof(data, "Got DISCONNECT\n");
*done = TRUE;
}
break;
case MQTT_CONNACK:
result = mqtt_verify_connack(data);
if(result)
break;
if(data->state.httpreq == HTTPREQ_POST) {
result = mqtt_publish(data);
if(!result) {
result = mqtt_disconnect(data);
*done = TRUE;
}
mqtt->nextstate = MQTT_FIRST;
}
else {
result = mqtt_subscribe(data);
if(!result) {
mqstate(data, MQTT_FIRST, MQTT_SUBACK);
}
}
break;
case MQTT_SUBACK:
case MQTT_PUBWAIT:
case MQTT_PUB_REMAIN:
result = mqtt_read_publish(data, done);
break;
default:
failf(data, "State not handled yet");
*done = TRUE;
break;
}
if(result == CURLE_AGAIN)
result = CURLE_OK;
return result;
}
#endif /* CURL_DISABLE_MQTT */
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