/* tiny -- tiny sender
 *
 * Copyright (C) 2010,2011 Olaf Bergmann <bergmann@tzi.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * This file is part of the CoAP library libcoap. Please see
 * README for terms of use.
 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <limits.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <signal.h>

#include <coap3/coap.h>

#define Nn 8 /* duplicate definition of N if built on sky motes */
#define ENCODE_HEADER_SIZE 4
#define HIBIT (1 << (Nn - 1))
#define EMASK ((1 << ENCODE_HEADER_SIZE) - 1)
#define MMASK ((1 << Nn) - 1 - EMASK)
#define MAX_VALUE ( (1 << Nn) - (1 << ENCODE_HEADER_SIZE) ) * (1 << ((1 << ENCODE_HEADER_SIZE) - 1))

#define COAP_PSEUDOFP_DECODE_8_4(r) (r < HIBIT ? r : (r & MMASK) << (r & EMASK))

/* ls and s must be integer variables */
/* #define COAP_PSEUDOFP_ENCODE_8_4_DOWN(v,ls) (v < HIBIT ? v : (ls = coap_fls(v) - Nn, (v >> ls) & MMASK) + ls) */
COAP_STATIC_INLINE unsigned char
COAP_PSEUDOFP_ENCODE_8_4_DOWN(unsigned int v, int *ls) {
 if (v < HIBIT)
 return v;
 *ls = coap_fls(v) - Nn;
 return ((v >> *ls) & MMASK) + *ls;
}
#define COAP_PSEUDOFP_ENCODE_8_4_UP(v,ls,s) (v < HIBIT ? v : (ls = coap_fls(v) - Nn, (s = (((v + ((1<<ENCODE_HEADER_SIZE<<ls)-1)) >> ls) & MMASK)), s == 0 ? HIBIT + ls + 1 : s + ls))

static int quit = 0;

/* SIGINT handler: set quit to 1 for graceful termination */
static void
handle_sigint(int signum COAP_UNUSED) {
 quit = 1;
}

static coap_pdu_t *
make_pdu(coap_session_t *session, unsigned int value) {
 coap_pdu_t *pdu;
 unsigned char enc;
 static unsigned char buf[20];
 int len, ls;

 if (!(pdu = coap_pdu_init(COAP_MESSAGE_NON, COAP_REQUEST_CODE_POST,
 coap_new_message_id(session), COAP_DEFAULT_MTU)))
 return NULL;

 enc = COAP_PSEUDOFP_ENCODE_8_4_DOWN(value, &ls);

 len = sprintf((char *)buf, "%c%u", enc, COAP_PSEUDOFP_DECODE_8_4(enc));
 coap_add_data(pdu, len, buf);

 return pdu;
}

static void
usage(const char *program) {
 const char *p;

 p = strrchr(program, '/');
 if (p)
 program = ++p;

 fprintf(stderr, "%s -- tiny fake sensor\n"
 "(c) 2010 Olaf Bergmann <bergmann@tzi.org>\n\n"
 "usage: %s [group address]\n"
 "\n\nSends some fake sensor values to specified multicast group\n",
 program, program);
}

static coap_session_t *
get_session(coap_context_t *ctx, const char *group) {
 int s;
 struct addrinfo hints;
 struct addrinfo *result, *rp;
 coap_session_t *session;
 int hops = 16;

 if (!ctx)
 return NULL;

 memset(&hints, 0, sizeof(struct addrinfo));
 hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
 hints.ai_socktype = SOCK_DGRAM; /* Coap uses UDP */
 hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST | AI_NUMERICSERV | AI_ALL;

 s = getaddrinfo(group, NULL, &hints, &result);
 if (s != 0) {
 fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
 return NULL;
 }

 /* iterate through results until success */
 for (rp = result; rp != NULL; rp = rp->ai_next) {
 coap_address_t addr;
 coap_address_init(&addr);
 addr.size = rp->ai_addrlen;
 memcpy(&addr.addr, rp->ai_addr, rp->ai_addrlen);

 session = coap_new_client_session(ctx, NULL, &addr, COAP_PROTO_UDP);
 if (!session)
 continue;

 if (coap_is_mcast(&addr)) {
 /* set socket options for multicast */
 if (!coap_mcast_set_hops(session, hops))
 perror("setsockopt: IPV6_MULTICAST_HOPS");

 }
 freeaddrinfo(result);
 return session;
 }

 fprintf(stderr, "no session available for group '%s'\n", group);
 freeaddrinfo(result);
 return NULL;
}

int
main(int argc, char **argv) {
 struct timeval tv;
 coap_pdu_t *pdu;
 coap_session_t *session;
 struct sigaction sa;
 coap_context_t *ctx;

 /* Initialize libcoap library */
 coap_startup();

 if (argc > 1 && strncmp(argv[1], "-h", 2) == 0) {
 usage(argv[0]);
 exit(1);
 }

 ctx = coap_new_context(NULL);
 if (!ctx)
 return -1;

 session = get_session(ctx, argc > 1 ? argv[1] : "::1");

 if (!session)
 return -1;

 memset(&sa, 0, sizeof(sa));
 sigemptyset(&sa.sa_mask);
 sa.sa_handler = handle_sigint;
 sa.sa_flags = 0;
 sigaction(SIGINT, &sa, NULL);
 sigaction(SIGTERM, &sa, NULL);
 /* So we do not exit on a SIGPIPE */
 sa.sa_handler = SIG_IGN;
 sigaction(SIGPIPE, &sa, NULL);

 while (!quit) {

 if (!(pdu = make_pdu(session, rand() & 0xfff)))
 break;

 coap_send(session, pdu);

 tv.tv_sec = 5;
 tv.tv_usec = 0;

 select(0, 0, 0, 0, &tv);

 }

 coap_free_context(ctx);
 coap_cleanup();

 return 0;
}