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mqtt-forward.c
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mqtt-forward.c
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#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <fcntl.h>
#include <unistd.h>
#include <mosquitto.h>
#include <getopt.h>
#include <poll.h>
#define MAX_SESSIONS 100
#define MAX_LIFETIME_SESSIONS (MAX_SESSIONS*100)
#define SESSION_RX_BUF_SIZE 10000
#define SESSION_BACKLOG_SIZE 200
#define TX_WINDOW_LIMIT 100
#define MAX_SERVER_LIST 30
#define MQTT_TOPIC_MAX_LEN 250
#define DBG_LOG_(fmt, ...) \
do { \
if (debug) \
printf(fmt, __VA_ARGS__); \
} while (0)
#define ENV_VAR_MQTT_HOST "MQTT_FORWARD_MQTT_HOST"
#define ENV_VAR_ROOT_CA "MQTT_FORWARD_ROOT_CA"
#define ENV_VAR_CERTIFICATE "MQTT_FORWARD_CERTIFICATE"
#define ENV_VAR_PRIVATE_KEY "MQTT_FORWARD_PRIVATE_KEY"
#define ENV_VAR_TOPIC_PREFIX "MQTT_FORWARD_TOPIC_PREFIX"
#define ENV_VAR_REMOTE_IP "MQTT_FORWARD_REMOTE_IP"
#define ENV_VAR_REMOTE_PORT "MQTT_FORWARD_REMOTE_PORT"
/**
* Internal types
*/
struct packet_backlog_data {
uint8_t *buf;
size_t len;
};
struct rx_packet_backlog {
struct packet_backlog_data backlog[SESSION_BACKLOG_SIZE];
uint64_t expected_seq_nbr;
int read_idx;
};
struct tx_packet_backlog {
struct packet_backlog_data backlog[SESSION_BACKLOG_SIZE];
uint64_t acked_seq_nbr;
int first_unacked_idx;
};
struct tcp_session_config {
uint32_t ip_addr;
uint16_t port;
};
struct tcp_session {
bool server_session;
char *session_id;
char *publish_topic;
int sock;
uint8_t *rx_buf;
uint64_t tx_seq_nbr;
struct rx_packet_backlog rx_backlog;
struct tx_packet_backlog tx_backlog;
struct tcp_session_config *session_cfg;
};
struct tcp_server_list {
char *server_id;
time_t last_seen_time;
};
/**
* Message types (all structs are packed)
*/
struct tcp_over_mqtt_hdr {
uint64_t seq_nbr;
uint64_t acked_seq_nbr;
#define TCP_OVER_MQTT_FLAG_TCP_DISCONNECT (1)
#define TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR (2)
#define TCP_OVER_MQTT_FLAG_NO_DATA (4)
#define TCP_OVER_MQTT_FLAG_BEACON (8)
#define TCP_OVER_MQTT_FLAG_REMOTE_CONFIG (16)
uint32_t flags;
uint32_t pad;
} __attribute__((packed));
struct tcp_over_mqtt_remote_config_hdr {
/**
* Total size (in bytes) of the config message
*/
uint32_t config_size;
/**
* Number of config items in the message
*/
uint32_t num_config_items;
uint8_t data[];
} __attribute__((packed));
struct tcp_over_mqtt_remote_config_item_hdr {
/**
* config_type has any of the values defined in
* enum tcp_over_mqtt_remote_config_type
*/
uint16_t config_type;
uint8_t data[];
} __attribute__((packed));
struct tcp_over_mqtt_remote_config_ip_addr {
uint32_t ip_addr;
} __attribute__((packed));
struct tcp_over_mqtt_remote_config_port {
uint16_t port;
} __attribute__((packed));
enum tcp_over_mqtt_remote_config_type {
REMOTE_CONFIG_TYPE_IP_ADDR,
REMOTE_CONFIG_TYPE_PORT,
};
/**
* Global variables
*/
static int tcp_client_listen_sock;
static int tcp_client_listen_port;
static int tcp_server_connect_port;
static pthread_t tcp_accept_thread;
static pthread_t beacon_print_thread;
static pthread_t beacon_tx_thread;
static pthread_t mqtt_create_thread;
static pthread_t tcp_rx_threads[MAX_SESSIONS];
static struct mosquitto *g_mqtt_client;
static bool connected_to_mqtt_server;
static bool server_mode;
static bool list_servers;
static bool transmit_beacons;
static struct tcp_session tcp_sessions[MAX_SESSIONS];
static struct sockaddr_in *tcp_server_addr;
static char *old_session_ids[MAX_LIFETIME_SESSIONS];
static size_t num_old_sessions;
static bool debug;
static struct tcp_server_list server_list[MAX_SESSIONS];
static pthread_mutex_t session_mtx = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t server_list_mtx = PTHREAD_MUTEX_INITIALIZER;
static bool use_tls;
static bool remote_tcp_port_set;
static bool remote_tcp_server_addr_set;
static uint32_t remote_tcp_server_addr;
static uint16_t remote_tcp_port;
static char server_mqtt_id[100];
static char client_mqtt_id[100];
static int mqtt_port;
static int mqtt_qos = 1;
static char mqtt_host[100];
static char mqtt_root_ca[100];
static char mqtt_certificate[100];
static char mqtt_private_key[100];
static char mqtt_topic_prefix[50];
static char tcp_server_addr_str[100];
static void clear_rx_packet_backlog(struct rx_packet_backlog *rx_backlog)
{
int i;
for (i = 0; i < SESSION_BACKLOG_SIZE; i++)
free(rx_backlog->backlog[i].buf);
memset(&rx_backlog->backlog[0],
0,
sizeof(rx_backlog->backlog[0])*SESSION_BACKLOG_SIZE);
}
static void clear_tx_packet_backlog(struct tx_packet_backlog *tx_backlog)
{
int i;
for (i = 0; i < SESSION_BACKLOG_SIZE; i++)
free(tx_backlog->backlog[i].buf);
memset(&tx_backlog->backlog[0],
0,
sizeof(tx_backlog->backlog[0])*SESSION_BACKLOG_SIZE);
}
static void clear_session(struct tcp_session *session_data)
{
fprintf(stderr, "%s: TCP session %s terminated\n", __func__, session_data->session_id);
pthread_mutex_lock(&session_mtx);
/* Store the session ID of the cleared session in the old session id
* array */
old_session_ids[num_old_sessions++] = session_data->session_id;
free(session_data->rx_buf);
free(session_data->publish_topic);
free(session_data->session_cfg);
clear_rx_packet_backlog(&session_data->rx_backlog);
clear_tx_packet_backlog(&session_data->tx_backlog);
memset(session_data, 0, sizeof(*session_data));
pthread_mutex_unlock(&session_mtx);
}
static char *gen_random_id(size_t n_nibbles)
{
FILE *fp;
int i;
uint8_t *id;
uint8_t nibble_1st;
uint8_t nibble_2nd;
char *random_id;
fp = fopen("/dev/urandom", "rb");
if (!fp) {
fprintf(stderr, "%s: unable to open /dev/urandom\n", __func__);
return NULL;
}
random_id = calloc(n_nibbles+1, 1);
id = calloc(n_nibbles/2, 1);
(void)fread(id, 1, n_nibbles/2, fp);
for (i = 0; i < n_nibbles/2; i++) {
nibble_1st = (id[i] & 0xf0) >> 4;
nibble_2nd = id[i] & 0x0f;
nibble_1st = (nibble_1st > 9) ? (nibble_1st - 10 + 'a') : (nibble_1st + '0');
nibble_2nd = (nibble_2nd > 9) ? (nibble_2nd - 10 + 'a') : (nibble_2nd + '0');
random_id[2*i] = nibble_1st;
random_id[2*i+1] = nibble_2nd;
}
free(id);
fclose(fp);
return random_id;
}
static void gen_client_id()
{
char *random_id;
random_id = gen_random_id(12);
snprintf(client_mqtt_id, sizeof(client_mqtt_id), "mqtt-forward-%s", random_id);
free(random_id);
}
static char *gen_session_id()
{
return gen_random_id(32);
}
static int create_config_header(const struct tcp_session_config *session_cfg,
uint8_t **cfg_hdr_buf,
size_t *cfg_hdr_size)
{
uint8_t *hdr_buf;
struct tcp_over_mqtt_remote_config_hdr *remote_cfg;
struct tcp_over_mqtt_remote_config_item_hdr *item_hdr;
struct tcp_over_mqtt_remote_config_ip_addr *item_ip_addr;
struct tcp_over_mqtt_remote_config_port *item_port;
char *tmp_ptr;
size_t hdr_size;
/* Calculate size of config header */
hdr_size = sizeof(struct tcp_over_mqtt_remote_config_hdr);
hdr_size += session_cfg->ip_addr ?
(sizeof(struct tcp_over_mqtt_remote_config_item_hdr) + sizeof(struct tcp_over_mqtt_remote_config_ip_addr)) : 0;
hdr_size += session_cfg->port ?
(sizeof(struct tcp_over_mqtt_remote_config_item_hdr) + sizeof(struct tcp_over_mqtt_remote_config_port)) : 0;
/* Allocate and populate config header */
hdr_buf = calloc(hdr_size, 1);
if (!hdr_buf) {
fprintf(stderr, "%s: Unable to allocate header buf\n", __func__);
return -1;
}
remote_cfg = (struct tcp_over_mqtt_remote_config_hdr *)hdr_buf;
remote_cfg->config_size = hdr_size;
item_hdr = (struct tcp_over_mqtt_remote_config_item_hdr *)remote_cfg->data;
tmp_ptr = (char*)item_hdr;
if (session_cfg->ip_addr) {
item_hdr->config_type = REMOTE_CONFIG_TYPE_IP_ADDR;
item_ip_addr =
(struct tcp_over_mqtt_remote_config_ip_addr *)item_hdr->data;
item_ip_addr->ip_addr = session_cfg->ip_addr;
tmp_ptr += sizeof(*item_hdr) + sizeof(*item_ip_addr);
remote_cfg->num_config_items++;
}
item_hdr = (struct tcp_over_mqtt_remote_config_item_hdr *)tmp_ptr;
if (session_cfg->port) {
item_hdr->config_type = REMOTE_CONFIG_TYPE_PORT;
item_port =
(struct tcp_over_mqtt_remote_config_port *)item_hdr->data;
item_port->port = session_cfg->port;
tmp_ptr += sizeof(*item_hdr) + sizeof(*item_ip_addr);
remote_cfg->num_config_items++;
}
*cfg_hdr_buf = hdr_buf;
*cfg_hdr_size = hdr_size;
return 0;
}
static void *tcp_session_rx_thread_fn(void *arg)
{
uint8_t *rx_buf;
uint8_t *cfg_hdr_buf;
size_t cfg_hdr_size;
int ret;
int recv_len;
struct tcp_session *session_data;
struct tcp_over_mqtt_hdr tx_hdr;
int sock;
int backlog_offset;
int backlog_write_idx;
char *topic;
struct tx_packet_backlog *tx_backlog;
struct rx_packet_backlog *rx_backlog;
struct timespec sleep_time = {.tv_nsec = 100000000};
struct pollfd fds = {.events = POLLIN};
session_data = (struct tcp_session *)arg;
rx_buf = session_data->rx_buf;
sock = session_data->sock;
fds.fd = sock;
topic = session_data->publish_topic;
tx_backlog = &session_data->tx_backlog;
rx_backlog = &session_data->rx_backlog;
cfg_hdr_size = 0;
if (!session_data->server_session && session_data->session_cfg) {
/* Create the config header that will be used in the first
* outgoing message (for clients only) */
ret = create_config_header(session_data->session_cfg,
&cfg_hdr_buf,
&cfg_hdr_size);
if (ret < 0)
goto out;
}
for (;;) {
pthread_mutex_lock(&session_mtx);
backlog_offset = session_data->tx_seq_nbr - tx_backlog->acked_seq_nbr - 1;
if (backlog_offset > TX_WINDOW_LIMIT) {
/* TX window is full. Stop reading more data from input
* socket and start re-transmit the lost frame */
struct tcp_over_mqtt_hdr *retransmit_tx_hdr =
(struct tcp_over_mqtt_hdr *)tx_backlog->backlog[tx_backlog->first_unacked_idx].buf;
if (rx_backlog->expected_seq_nbr > 1) {
retransmit_tx_hdr->flags |= TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR;
retransmit_tx_hdr->acked_seq_nbr =
rx_backlog->expected_seq_nbr - 1;
} else {
retransmit_tx_hdr->flags = 0;
}
DBG_LOG_("Session %s: TX RETRANSMIT: %4lu. Acked %4lu\n",
session_data->session_id,
retransmit_tx_hdr->seq_nbr,
retransmit_tx_hdr->acked_seq_nbr);
ret = mosquitto_publish(g_mqtt_client,
NULL,
topic,
tx_backlog->backlog[tx_backlog->first_unacked_idx].len,
tx_backlog->backlog[tx_backlog->first_unacked_idx].buf,
mqtt_qos,
false /*retain*/);
pthread_mutex_unlock(&session_mtx);
(void)nanosleep(&sleep_time, NULL);
} else {
/* Only read from TCP socket if the TX window is not exceeded */
pthread_mutex_unlock(&session_mtx);
ret = poll(&fds, 1, 500);
if (ret < 0) {
fprintf(stderr, "%s: poll errno: %d\n", __func__, errno);
break;
} else if (ret == 0) {
/* Timeout */
tx_hdr.seq_nbr = 0;
tx_hdr.flags = TCP_OVER_MQTT_FLAG_NO_DATA;
if (rx_backlog->expected_seq_nbr > 1) {
tx_hdr.flags |= TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR;
tx_hdr.acked_seq_nbr =
rx_backlog->expected_seq_nbr - 1;
}
tx_hdr.flags |= cfg_hdr_size ?
TCP_OVER_MQTT_FLAG_REMOTE_CONFIG : 0;
memcpy(rx_buf, &tx_hdr, sizeof(tx_hdr));
recv_len = sizeof(tx_hdr);
if (cfg_hdr_size) {
memcpy(rx_buf + sizeof(tx_hdr), cfg_hdr_buf, cfg_hdr_size);
recv_len += cfg_hdr_size;
/* The config header is only used in the first
* message */
free(cfg_hdr_buf);
cfg_hdr_buf = NULL;
cfg_hdr_size = 0;
}
DBG_LOG_("Session %s: TX HEARTBEAT: %4lu. Acked %4lu\n",
session_data->session_id,
tx_hdr.seq_nbr,
tx_hdr.acked_seq_nbr);
ret = mosquitto_publish(g_mqtt_client,
NULL,
topic,
recv_len,
rx_buf,
mqtt_qos,
false /*retain*/);
if (ret) {
fprintf(stderr, "Publishing on topic %s failed. Result %d\n",
topic,
ret);
break;
}
continue;
}
/* Data has been received on socket */
recv_len = recv(sock,
rx_buf + sizeof(tx_hdr) + cfg_hdr_size,
SESSION_RX_BUF_SIZE - sizeof(tx_hdr) - cfg_hdr_size,
0);
if (recv_len < 0) {
fprintf(stderr, "%s: recv errno: %d\n", __func__, errno);
break;
} else if (recv_len == 0) {
fprintf(stderr, "%s: TCP connection terminated\n", __func__);
break;
}
pthread_mutex_lock(&session_mtx);
tx_hdr.seq_nbr = session_data->tx_seq_nbr;
tx_hdr.flags = 0;
if (rx_backlog->expected_seq_nbr > 1) {
tx_hdr.flags |= TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR;
tx_hdr.acked_seq_nbr = rx_backlog->expected_seq_nbr - 1;
}
tx_hdr.flags |= cfg_hdr_size ?
TCP_OVER_MQTT_FLAG_REMOTE_CONFIG : 0;
memcpy(rx_buf, &tx_hdr, sizeof(tx_hdr));
recv_len += sizeof(tx_hdr);
if (cfg_hdr_size) {
memcpy(rx_buf + sizeof(tx_hdr), cfg_hdr_buf, cfg_hdr_size);
recv_len += cfg_hdr_size;
/* The config header is only used in the first
* message */
free(cfg_hdr_buf);
cfg_hdr_buf = NULL;
cfg_hdr_size = 0;
}
/* re-read backlog_offset since acked_seq_nbr might have
* been update during the sleep of this thread. */
backlog_offset = session_data->tx_seq_nbr - tx_backlog->acked_seq_nbr - 1;
backlog_write_idx =
(tx_backlog->first_unacked_idx + backlog_offset) % SESSION_BACKLOG_SIZE;
if (tx_backlog->backlog[backlog_write_idx].buf) {
fprintf(stderr, "Session: %s: Backlog index %d already has an allocated buffer!\n",
session_data->session_id,
backlog_write_idx);
free(tx_backlog->backlog[backlog_write_idx].buf);
}
tx_backlog->backlog[backlog_write_idx].buf = malloc(recv_len);
tx_backlog->backlog[backlog_write_idx].len = recv_len;
memcpy(tx_backlog->backlog[backlog_write_idx].buf, rx_buf, recv_len);
session_data->tx_seq_nbr++;
DBG_LOG_("Session %s: TX: %4lu. Acked %4lu\n",
session_data->session_id,
tx_hdr.seq_nbr,
tx_hdr.acked_seq_nbr);
pthread_mutex_unlock(&session_mtx);
ret = mosquitto_publish(g_mqtt_client,
NULL,
topic,
recv_len,
rx_buf,
mqtt_qos,
false /*retain*/);
if (ret) {
fprintf(stderr, "Publishing on topic %s failed. Result %d\n",
topic,
ret);
break;
}
}
}
out:
fprintf(stderr, "%s: TCP session ended\n", __func__);
clear_session(session_data);
return NULL;
}
static int connect_server_session(const struct tcp_session_config *session_cfg,
int *tcp_sock)
{
int ret;
static struct sockaddr_in server_addr;
server_addr = *tcp_server_addr;
/* Create TCP socket and connect to the server*/
*tcp_sock = socket(AF_INET, SOCK_STREAM, 0);
if (session_cfg) {
if (session_cfg->ip_addr)
server_addr.sin_addr.s_addr = session_cfg->ip_addr;
if (session_cfg->port)
server_addr.sin_port = htons(session_cfg->port);
}
ret = connect(*tcp_sock,
(const struct sockaddr *) &server_addr,
sizeof(server_addr));
if (ret) {
fprintf(stderr, "%s: Unable to establish TCP connection. errno %d\n",
__func__, errno);
return -1;
}
return 0;
}
static int create_session(const char *session_id,
size_t session_id_len,
size_t *session_nbr,
int tcp_sock,
bool server_session,
struct tcp_session_config *session_cfg)
{
int ret;
size_t session_nbr_local;
char *session_id_local;
for (session_nbr_local = 0;
session_nbr_local < MAX_SESSIONS;
session_nbr_local++) {
if (!tcp_sessions[session_nbr_local].session_id)
break;
}
if (session_nbr_local >= MAX_SESSIONS) {
fprintf(stderr, "%s: No empty session slot found for new session\n",
__func__);
return -1;
}
/* Server sessions are created from a received session ID.
* Clients will create their own ID */
if (server_session) {
session_id_local = calloc(session_id_len + 1, 1);
strncpy(session_id_local,
session_id,
session_id_len);
} else {
session_id_local = gen_session_id();
}
if (server_session) {
ret = connect_server_session(session_cfg, &tcp_sock);
if (ret)
return -1;
} else {
/* Subscribe to data from the server for this session_id */
int mid;
char topic[MQTT_TOPIC_MAX_LEN];
snprintf(topic,
sizeof(topic),
"%s/%s/%s/rx",
mqtt_topic_prefix,
server_mqtt_id,
session_id_local);
ret = mosquitto_subscribe(g_mqtt_client,
&mid,
topic,
mqtt_qos);
if (ret) {
fprintf(stderr, "%s: mosquitto_subscribe %d (failed to subscribe to topic %s)\n",
__func__, ret, topic);
return -1;
}
fprintf(stderr, "%s: subscribed to %s\n", __func__, topic);
}
/* Create a session struct for the session*/
memset(&tcp_sessions[session_nbr_local], 0, sizeof(tcp_sessions[0]));
tcp_sessions[session_nbr_local].server_session = server_session;
tcp_sessions[session_nbr_local].session_id = session_id_local;
tcp_sessions[session_nbr_local].sock = tcp_sock;
tcp_sessions[session_nbr_local].rx_buf = calloc(SESSION_RX_BUF_SIZE, 1);
tcp_sessions[session_nbr_local].rx_backlog.expected_seq_nbr = 1;
tcp_sessions[session_nbr_local].tx_seq_nbr = 1;
tcp_sessions[session_nbr_local].publish_topic = calloc(MQTT_TOPIC_MAX_LEN, 1);
tcp_sessions[session_nbr_local].session_cfg = session_cfg;
if (server_session)
snprintf(tcp_sessions[session_nbr_local].publish_topic,
MQTT_TOPIC_MAX_LEN,
"%s/%s/%s/rx",
mqtt_topic_prefix,
server_mqtt_id,
session_id_local);
else
snprintf(tcp_sessions[session_nbr_local].publish_topic,
MQTT_TOPIC_MAX_LEN,
"%s/%s/%s/tx",
mqtt_topic_prefix,
server_mqtt_id,
session_id_local);
fprintf(stderr, "%s: Creating session thread for session %s, session number %lu\n",
__func__,
tcp_sessions[session_nbr_local].session_id,
session_nbr_local);
ret = pthread_create(&tcp_rx_threads[session_nbr_local],
NULL,
&tcp_session_rx_thread_fn,
&tcp_sessions[session_nbr_local]);
if (ret) {
fprintf(stderr, "%s: pthread_create %d\n", __func__, errno);
return -1;
}
*session_nbr = session_nbr_local;
return 0;
}
static void *tcp_accept_thread_fn(void *arg)
{
struct sockaddr_in client_addr;
socklen_t addr_len = sizeof(client_addr);
int ret;
int client_sock;
size_t session_nbr;
struct tcp_session_config *session_cfg;
for (;;) {
client_sock = accept(tcp_client_listen_sock,
(struct sockaddr *)&client_addr,
&addr_len);
fprintf(stderr, "%s: Accepted TCP connection\n", __func__);
if (client_sock < 0) {
fprintf(stderr, "connect to remote server failed. errno %d\n", errno);
close(client_sock);
continue;
}
session_cfg = NULL;
if (remote_tcp_port_set ||remote_tcp_server_addr_set ) {
session_cfg = calloc(sizeof(*session_cfg), 1);
session_cfg->ip_addr =
remote_tcp_server_addr_set ? remote_tcp_server_addr : 0;
session_cfg->port =
remote_tcp_port_set ? remote_tcp_port : 0;
}
pthread_mutex_lock(&session_mtx);
ret = create_session(NULL, /*client session*/
0,
&session_nbr,
client_sock,
false, /*client session*/
session_cfg);
pthread_mutex_unlock(&session_mtx);
if (ret < 0) {
fprintf(stderr, "%s: Unable to create client session\n", __func__);
close(client_sock);
continue;
}
}
return NULL;
}
static void *create_thread_fn(void *arg)
{
int ret;
struct timespec ts = {.tv_sec = 5};
(void)arg;
for (;;) {
if (connected_to_mqtt_server) {
(void)nanosleep(&ts, NULL);
continue;
}
ret = mosquitto_connect_async(g_mqtt_client,
mqtt_host,
mqtt_port,
20);
if (ret != MOSQ_ERR_SUCCESS) {
fprintf(stderr, "%s: mosquitto_connect_async %d\n",
__func__, ret);
/* Try again */
fprintf(stderr, "%s: Unable to connect to %s. Retrying in %ld sec\n",
__func__, mqtt_host, ts.tv_sec);
}
(void)nanosleep(&ts, NULL);
}
return NULL;
}
static void *beacon_tx_thread_fn(void *arg)
{
struct timespec ts = {.tv_sec = 3};
struct tcp_over_mqtt_hdr msg_hdr = {.flags = TCP_OVER_MQTT_FLAG_BEACON};
char topic[MQTT_TOPIC_MAX_LEN];
snprintf(topic, sizeof(topic), "%s/%s/beacon/rx", mqtt_topic_prefix, server_mqtt_id);
for (;;) {
if (!connected_to_mqtt_server) {
(void)nanosleep(&ts, NULL);
continue;
}
(void)mosquitto_publish(g_mqtt_client,
NULL,
topic,
sizeof(msg_hdr),
&msg_hdr,
mqtt_qos,
false /*retain*/);
(void)nanosleep(&ts, NULL);
}
return NULL;
}
static void *beacon_print_thread_fn(void *arg)
{
size_t server_nbr;
time_t cur_time;
struct timespec ts = {.tv_sec = 3};
for (;;) {
(void)nanosleep(&ts, NULL);
pthread_mutex_lock(&server_list_mtx);
cur_time = time(NULL);
/* Print the server list */
printf("Detected servers:\n\n");
printf(" %40s%30s\n\n", "Server ID", "Last seen (seconds ago)");
for (server_nbr = 0; server_nbr < MAX_SERVER_LIST; server_nbr++) {
if (!server_list[server_nbr].server_id)
break;
printf(" %40s%30ld\n",
server_list[server_nbr].server_id,
cur_time - server_list[server_nbr].last_seen_time);
}
printf("\n\n");
pthread_mutex_unlock(&server_list_mtx);
}
return NULL;
}
static void handle_mqtt_message_list_servers(const char *recvd_client_id,
size_t recvd_client_id_len)
{
size_t server_nbr;
time_t cur_time;
pthread_mutex_lock(&server_list_mtx);
cur_time = time(NULL);
/* Add the server to the server list */
for (server_nbr = 0; server_nbr < MAX_SERVER_LIST; server_nbr++) {
if (!server_list[server_nbr].server_id) {
server_list[server_nbr].server_id =
calloc(recvd_client_id_len + 1, 1);
strncpy(server_list[server_nbr].server_id,
recvd_client_id,
recvd_client_id_len);
server_list[server_nbr].last_seen_time = cur_time;
break;
}
if (strncmp(server_list[server_nbr].server_id,
recvd_client_id,
recvd_client_id_len) == 0) {
server_list[server_nbr].last_seen_time = cur_time;
break;
}
}
pthread_mutex_unlock(&server_list_mtx);
if (server_nbr >= MAX_SERVER_LIST)
fprintf(stderr, "Server list exhausted!\n");
}
static void handle_remote_config(struct tcp_over_mqtt_remote_config_hdr *remote_cfg,
struct tcp_session_config *session_cfg)
{
int cfg_idx;
struct tcp_over_mqtt_remote_config_item_hdr *item_hdr;
struct tcp_over_mqtt_remote_config_ip_addr *item_ip_addr;
struct tcp_over_mqtt_remote_config_port *item_port;
char *tmp_ptr;
item_hdr = (struct tcp_over_mqtt_remote_config_item_hdr *)remote_cfg->data;
for (cfg_idx = 0; cfg_idx < remote_cfg->num_config_items; cfg_idx++) {
tmp_ptr = (char*)item_hdr;
switch (item_hdr->config_type) {
case REMOTE_CONFIG_TYPE_IP_ADDR:
item_ip_addr =
(struct tcp_over_mqtt_remote_config_ip_addr *)item_hdr->data;
session_cfg->ip_addr = item_ip_addr->ip_addr;
tmp_ptr += sizeof(*item_hdr) + sizeof(*item_ip_addr);
break;
case REMOTE_CONFIG_TYPE_PORT:
item_port =
(struct tcp_over_mqtt_remote_config_port *)item_hdr->data;
session_cfg->port = item_port->port;
tmp_ptr += sizeof(*item_hdr) + sizeof(*item_port);
break;
default:
goto out;
}
item_hdr = (struct tcp_over_mqtt_remote_config_item_hdr *)tmp_ptr;
}
out:
return;
}
static void handle_mqtt_message(uint8_t *msg,
int msg_len,
const char *session_id,
size_t session_id_len,
const char *recvd_client_id,
size_t recvd_client_id_len,
bool server_session)
{
int ret;
int i;
int data_len;
uint8_t *data;
int backlog_write_idx;
int backlog_offset;
struct tcp_over_mqtt_hdr *rx_hdr;
struct tcp_over_mqtt_remote_config_hdr *remote_cfg;
struct rx_packet_backlog *rx_backlog;
struct tx_packet_backlog *tx_backlog;
size_t session_nbr;
size_t remote_cfg_offset = 0;
struct tcp_session_config *session_cfg = NULL;
rx_hdr = (struct tcp_over_mqtt_hdr *) msg;
if (rx_hdr->flags & TCP_OVER_MQTT_FLAG_BEACON) {
if (list_servers)
handle_mqtt_message_list_servers(recvd_client_id,
recvd_client_id_len);
return;
}
/* Check if there is a session for this session ID */
for (session_nbr = 0; session_nbr < MAX_SESSIONS; session_nbr++) {
if ((tcp_sessions[session_nbr].session_id) &&
(strncmp(tcp_sessions[session_nbr].session_id, session_id, session_id_len) == 0)) {
break;
}
}
if (session_nbr >= MAX_SESSIONS) {
/* No session for this session ID. If we are running as a client
* we should discard this message. If running as a server we
* should create a new session */
if (!server_session)
return;
/* Before a new session is created we must check if the message
* belongs to an old session. In this case it should be
* discarded */
for (i = 0; i < num_old_sessions; i++) {
if (strncmp(old_session_ids[i], session_id, session_id_len) == 0) {
fprintf(stderr, "%s: Session ID %s is an old session. Message discarded\n",
__func__, old_session_ids[i]);
return;
}
}
if (rx_hdr->flags & TCP_OVER_MQTT_FLAG_REMOTE_CONFIG) {
remote_cfg = (struct tcp_over_mqtt_remote_config_hdr *)(msg + sizeof(*rx_hdr));
remote_cfg_offset = remote_cfg->config_size;
session_cfg = calloc(sizeof(*session_cfg), 1);
handle_remote_config(remote_cfg, session_cfg);
}
pthread_mutex_lock(&session_mtx);
ret = create_session(session_id,
session_id_len,
&session_nbr,
0,
true, /*server session*/
session_cfg);
pthread_mutex_unlock(&session_mtx);
if (ret)
return;
}
rx_backlog = &tcp_sessions[session_nbr].rx_backlog;
tx_backlog = &tcp_sessions[session_nbr].tx_backlog;
if (rx_hdr->flags & TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR)
DBG_LOG_("Session %s: RX: %4lu. Remote acked %4lu\n",
tcp_sessions[session_nbr].session_id,
rx_hdr->seq_nbr,
rx_hdr->acked_seq_nbr);
else
DBG_LOG_("Session %s: RX: %4lu. No remote ack\n",
tcp_sessions[session_nbr].session_id,
rx_hdr->seq_nbr);
pthread_mutex_lock(&session_mtx);
if (rx_hdr->flags & TCP_OVER_MQTT_FLAG_ACKED_SEQ_NBR) {
if (rx_hdr->acked_seq_nbr >= tcp_sessions[session_nbr].tx_seq_nbr) {
/* The acked sequence number can't equal or exceed the
* TX sequence number we are about to send. In this
* case, the received frame is some kind of artifact
* from a previous session. The session is thus invalid
* and should be removed. */
clear_session(&tcp_sessions[session_nbr]);
return;
}
for (i = tx_backlog->acked_seq_nbr; i < rx_hdr->acked_seq_nbr; i++) {
if (!tx_backlog->backlog[tx_backlog->first_unacked_idx].buf) {
fprintf(stderr, "%s: TX backlog index %d already free'd!\n",
__func__, tx_backlog->first_unacked_idx);
continue;
}
free(tx_backlog->backlog[tx_backlog->first_unacked_idx].buf);
tx_backlog->backlog[tx_backlog->first_unacked_idx].buf = NULL;
tx_backlog->backlog[tx_backlog->first_unacked_idx].len = 0xdead;
tx_backlog->first_unacked_idx++;
tx_backlog->first_unacked_idx %= SESSION_BACKLOG_SIZE;
}
tx_backlog->acked_seq_nbr = (rx_hdr->acked_seq_nbr > tx_backlog->acked_seq_nbr) ?
rx_hdr->acked_seq_nbr : tx_backlog->acked_seq_nbr;
}
pthread_mutex_unlock(&session_mtx);
if (rx_hdr->flags & TCP_OVER_MQTT_FLAG_NO_DATA) {
DBG_LOG_("Session %s: No data frame received\n",
tcp_sessions[session_nbr].session_id);
return;
}
data_len = msg_len - sizeof(*rx_hdr) - remote_cfg_offset;
data = msg + sizeof(*rx_hdr) + remote_cfg_offset;
if (data_len <= 0) {
/* Invalid data */
return;
}