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/*
* Hot Beverage Companion – desktop app network module
*
* Copyright (C) 2017 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 <string.h>
#include <time.h>
#include <stdlib.h>
#include "net.h"
struct netstate_internal {
int (*getlastdata)(char * const data, struct netstate * const state);
unsigned int handle;
struct timespec lastreply;
int sock;
};
static int dolisten(char * const data, struct netstate_internal * const state);
static int getpacket(char *data, size_t buffsize, int sock, struct sockaddr_in *sender);
static int getlastdata_internal(char * const data, struct netstate * const state);
struct netstate *net_init(const unsigned int port)
{
struct netstate_internal *ret;
struct sockaddr_in bindaddress = {0};
ret = malloc(sizeof(struct netstate_internal));
bindaddress.sin_family = AF_INET;
bindaddress.sin_port = htons(port);
ret->sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (bind(ret->sock, (struct sockaddr*) &bindaddress, sizeof(bindaddress))) {
free(ret);
return NULL;
}
clock_gettime(CLOCK_MONOTONIC_RAW, &ret->lastreply);
ret->lastreply.tv_sec -= 5;
ret->handle = 0; /* currently unused */
ret->getlastdata = &getlastdata_internal;
return (struct netstate *) ret;
}
int net_close(struct netstate **state) {
close((*(struct netstate_internal **)state)->sock);
free(*state);
*state = NULL;
return 0;
}
static int dolisten(char * const data, struct netstate_internal * const state)
{
char buff[9001] = {0};
static const char servermagic[] = "I love coffee!";
static const char clientmagic[] = "I love tea!";
struct timespec now;
struct timespec wait = {0, 25 * 1000 * 1000};
struct sockaddr_in clientaddr;
size_t i = 10;
int ret;
do {
clock_gettime(CLOCK_MONOTONIC_RAW, &now);
ret = getpacket(buff, sizeof(buff), state->sock, &clientaddr);
switch (ret) {
case NET_OK:
state->lastreply = now;
if (buff[0] == 'I') {
if (!(strcmp(buff, servermagic))) {
sendto(state->sock, clientmagic, sizeof(clientmagic),
MSG_DONTWAIT, (struct sockaddr *) &clientaddr, sizeof(clientaddr));
}
ret = NET_NONEWDATA; /* consume packet and lie about it */
continue;
} else {
memcpy(data, buff, 8ul);
}
break;
default:
; /* noop */
}
if (!ret) {
nanosleep(&wait, NULL);
}
} while (--i && ret != 0);
/* no packets in five seconds */
if ((now.tv_sec - state->lastreply.tv_sec) >= 5) {
ret = NET_DEAD;
}
return ret;
}
static int getpacket(char *data, size_t buffsize, 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) {
recvfrom(sock, data, buffsize, MSG_DONTWAIT, (struct sockaddr *) sender, &sender_len);
ret = NET_OK;
} else {
ret = NET_NONEWDATA;
}
return ret;
}
static int getlastdata_internal(char * const data, struct netstate * const state)
{
return dolisten(data, (struct netstate_internal *) state);
}
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