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/*
* Hot Beverage Companion – desktop app network module
*
* Copyright (C) 2017-2018 Gediminas Jakutis
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; version 2.1
* of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <poll.h>
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include "net.h"
struct netstate {
struct timespec lastreply;
int nd;
int sock;
unsigned short int port;
pthread_t listner;
char *data;
size_t bufsize;
unsigned int available;
int status;
pthread_mutex_t datamutex;
};
static pthread_mutex_t initmutex = PTHREAD_MUTEX_INITIALIZER;
static struct netstate *state;
static ssize_t count;
static size_t available_count;
static void *dolisten(void * state);
static int getpacket(char *data, size_t buffsize, ssize_t *recvbufsize, int sock, struct sockaddr_in *sender);
int net_init(const unsigned short int port)
{
struct sockaddr_in bindaddress = {0};
int ret;
ssize_t i;
int sizechanged = 0;
pthread_mutex_lock(&initmutex);
if (available_count) {
for (i = 0; !state[i].available; ++i) {
if (i == count) {
ret = NET_ERROR;
goto out;
}
}
} else {
if (++count == INT_MAX) {
ret = NET_ERROR;
goto out;
}
i = count - 1;
state = realloc(state, sizeof(struct netstate) * count);
sizechanged = 1;
}
state[i].available = 0;
bindaddress.sin_family = AF_INET;
bindaddress.sin_port = htons(port);
state[i].sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (bind(state[i].sock, (struct sockaddr*) &bindaddress, sizeof(bindaddress))) {
ret = NET_ERROR;
goto out;
}
clock_gettime(CLOCK_MONOTONIC_RAW, &state[i].lastreply);
state[i].lastreply.tv_sec -= 5;
state[i].nd = i + 1;
state[i].port = port;
state[i].data = malloc(dgsize);
memset(state[i].data, 0, dgsize);
state[i].bufsize = dgsize;
state[i].status = NET_NONEWDATA;
pthread_mutex_init(&state[i].datamutex, NULL);
if (pthread_create(&state[i].listner, NULL, dolisten, state + i)) {
ret = NET_ERROR;
goto out;
}
ret = count;
out:
if (ret == NET_ERROR && sizechanged) {
state = realloc(state, sizeof(struct netstate) * --count);
}
pthread_mutex_unlock(&initmutex);
return ret;
}
int net_close(int nd)
{
int ret;
pthread_mutex_lock(&initmutex);
if (nd > count || nd < 1 || state[nd - 1].available) {
ret = NET_ERROR;
} else {
--nd;
pthread_cancel(state[nd].listner);
pthread_join(state[nd].listner, NULL);
close(state[nd].sock);
free(state[nd].data);
state[nd].available = 1;
ret = NET_OK;
}
pthread_mutex_unlock(&initmutex);
return ret;
}
int net_getlastdata(int nd, char * const data)
{
int ret;
if (nd > count || nd < 1 || state[--nd].available) {
ret = NET_ERROR;
} else if (!(ret = state[nd].status)) {
memcpy(data, state[nd].data, dgsize);
}
return ret;
}
static void *dolisten(void * state)
{
static const char servermagic[] = "I love coffee!";
static const char clientmagic[] = "I love tea!";
struct timespec now;
struct timespec wait = {0, 10 * 1000 * 1000}; /* 10 ms */
struct sockaddr_in clientaddr;
struct netstate *st;
ssize_t recvbufsize;
int cancelstate;
st = state;
do {
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
pthread_mutex_lock(&st->datamutex);
clock_gettime(CLOCK_MONOTONIC_RAW, &now);
st->status = getpacket(st->data, st->bufsize, &recvbufsize, st->sock, &clientaddr);
if (!st->status) {
st->lastreply = now;
if (st->data[0] == 'I' && !(strcmp(st->data, servermagic))) {
sendto(st->sock, clientmagic, sizeof(clientmagic),
MSG_DONTWAIT, (struct sockaddr *) &clientaddr, sizeof(clientaddr));
st->status = NET_NONEWDATA; /* consume packet and lie about it */
}
}
/* no packets in five seconds */
if ((now.tv_sec - st->lastreply.tv_sec) >= 5) {
st->status = NET_DEAD;
} else if (st->data[0] != 'I') {
/* we don't actually want to have NONEWDATA set from this loop,
* barring the one exeption that is after arrival of the beacon
* packet, as it'd keep the value at NONEWDATA almost constantly
* due to polling being generally much more frequent than the
* actual packet rate.
*/
st->status = NET_OK;
}
pthread_mutex_unlock(&st->datamutex);
pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &cancelstate);
pthread_testcancel();
nanosleep(&wait, NULL);
} while (1);
return NULL;
}
static int getpacket(char *data, size_t buffsize, ssize_t *recvbufsize, int sock, struct sockaddr_in *sender)
{
static struct pollfd pfd = {0};
int ret;
socklen_t sender_len = sizeof(*sender);
if (!pfd.fd) {
pfd.fd = sock;
pfd.events = POLLIN;
pfd.revents = 0;
}
ret = poll(&pfd, 1, 0);
if (ret < 0) {
/* NOOP */
} else if (!ret) {
ret = NET_NONEWDATA;
} else if (pfd.revents & POLLIN) {
*recvbufsize = recvfrom(sock, data, buffsize, MSG_DONTWAIT, (struct sockaddr *) sender, &sender_len);
ret = NET_OK;
} else {
ret = NET_NONEWDATA;
}
return ret;
}
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