tcp-pcm-receiver/src/main.c

/*
 * SPDX-FileCopyrightText: 2019 Helmut Pozimski <helmut@pozimski.eu>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */

#include <signal.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <getopt.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <time.h>
#include <sys/time.h>
#include <syslog.h>

#include "tcpserver.h"
#include "wavfile.h"

#define BUF_SIZE 1558
#define MAX_PATH_LEN 255

typedef struct {
	uint32_t sample_rate;
	uint32_t bits;
} sync_information;

typedef struct {
	char ack[4];
	sync_information sync;
} sync_ack;

/* global variables */
char filepath[MAX_PATH_LEN + 30];
uint8_t file_closed = -1;
wavfile * file;
int sock;

/*
 * Function: signal_handler
 * ------------------------
 *     handles TERM and INT to ensure an orderly shutdown
 *
 * signal: the number of the signal sent
 */
static void signal_handler(int signal) {
	syslog(LOG_INFO, "signal %d received, shutting down\n", signal);
	if (!file_closed) {
		wavfile_close(file);
	}
	tcpserver_stop(sock);
	exit(EXIT_SUCCESS);
}

/*
 * Function: construct_file_path
 * ----------------------------------------
 *     Constructs the file path to write a new file to
 * 
 * directory: directory in which the file should be placed
 * file_path: pointer to the buffer to write the file path to
 */
static void construct_file_path(char * directory, char * file_path) {
	time_t cur_time;
	struct tm local_time;
	char timebuffer[12];
    	cur_time = time(NULL);
	local_time = (*localtime(&cur_time));
	strncpy(file_path, "", 1);
	strncat(file_path, directory, 255);
	strncat(file_path, "/", 2);
	sprintf(timebuffer, "%d", local_time.tm_year +1900);
	strncat(file_path, timebuffer, 12);
	sprintf(timebuffer, "%d", local_time.tm_mon +1);
	strncat(file_path, timebuffer, 12);
	sprintf(timebuffer, "%d", local_time.tm_mday);
	strncat(file_path, timebuffer, 12);
	sprintf(timebuffer, "%d", local_time.tm_hour);
	strncat(file_path, timebuffer, 12);
	sprintf(timebuffer, "%d", local_time.tm_min);
	strncat(file_path, timebuffer, 12);
	sprintf(timebuffer, "%d", local_time.tm_sec);
	strncat(file_path, timebuffer, 12);
	strncat(file_path, "-recording.wav", 15);
}


int main(int argc, char **argv) {
	char * ip_address = NULL;
	char * directory = NULL;
	uint16_t port = 0;
	int opt, bytes_received, conn;
	struct sockaddr_in client;
	unsigned int namelen;
	sync_information sync;
	uint8_t buffer[BUF_SIZE];
	sync_ack ack_packet;
	while ((opt = getopt(argc, argv, "i:p:d:")) != -1) {
		switch(opt) {
			case 'i':
				ip_address = optarg;
				break;
			case 'p':
				port = strtoul(optarg, NULL, 10);
				break;
			case 'd':
				directory = optarg;
				break;
		}
	}
	if (port == 0 || ip_address == NULL || directory == NULL) {
		printf("Usage: %s -i IPV4_ADDRESS -p PORT -d DIRECTORY\n", argv[0]);
		return EXIT_SUCCESS;
	}
	struct sigaction action;
	action.sa_handler = signal_handler;
	sigaction(SIGTERM, &action,NULL);
	sigaction(SIGINT, &action,NULL);
	openlog("tpr", LOG_CONS | LOG_PID, LOG_DAEMON);
	if ((sock = tcpserver_start(ip_address, port)) < 0 ) {
		syslog(LOG_ERR, "Failed to start TCP server\n");
		return EXIT_FAILURE;
	}
	namelen = sizeof(client);
	while (1) {
		conn = accept(sock, (struct sockaddr *)&client, &namelen);
		if (conn == -1) {
			continue;
		}
		struct timeval tv;
		tv.tv_sec = 3;
		tv.tv_usec = 0;
		setsockopt(conn, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof tv);
		recv(conn, &sync, sizeof(sync), 0);
		if (sync.sample_rate < 8000 || sync.sample_rate > 48000) {
			syslog(LOG_ERR, "Invalid sample rate received\n");
			continue;
		}
		construct_file_path(directory, filepath);
		syslog(LOG_INFO, "opening file at: %s\n", filepath);
		file = wavfile_create(filepath, 1, sync.sample_rate, sync.bits);
		file_closed = 0;
		strncpy(ack_packet.ack,"ACK", 4);
		if (file == NULL) {
			syslog(LOG_ERR, "Error creating new file\n");
			close(conn);
			continue;
		}
		ack_packet.sync = sync;
		send(conn, &ack_packet, sizeof(ack_packet), 0);
		while ((bytes_received = recv(conn, buffer, BUF_SIZE, 0)) != -1) {
			wavfile_append_data(file, buffer, bytes_received);		
		}
		syslog(LOG_INFO, "closing file: %s\n", filepath);
		wavfile_close(file);
		close(conn);
		file_closed = 1;
	}
	return EXIT_SUCCESS;
}