#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int argc, char **argv)
{
	int sock;
	int ret;
	unsigned int fsize;
	unsigned int count = 0;
	unsigned int prev;
	unsigned short port = 5000;
	char fname[128];
	char cfsize[12];
	char buf[65536];
	FILE* outf;
	struct sockaddr_in addr;

	if (argc != 3) {
		fprintf(stderr, "Usage: %s IP_addr filename\n", argv[0]);
		exit(1);
	}

	memset(&addr, 0, sizeof(addr));
	ret = inet_aton(argv[1], &addr.sin_addr);
	if (!ret) {
		fprintf(stderr, "invalid IP address %s\n", argv[1]);
		exit(1);
	}

	ret = sscanf(argv[2], "%s", fname);
	if (ret != 1) {
		fprintf(stderr, "filename error");
		exit(1);
	}

	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);

	sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
	if (sock == -1) {
		perror("socket()");
		exit(1);
	}

	ret = connect(sock, (struct sockaddr *)&addr, sizeof(addr));
	if (ret == -1) {
		perror("connect()");
		fprintf(stderr, "connection failed\n");
		exit(1);
	}

	fprintf(stderr, "connected...\n");

	/* send the filename to the server */
	ret = send(sock, fname, strlen(fname), 0);
	if (ret == -1) {
		perror("send()");
		fprintf(stderr, "send failed\n");
		exit(1);
	}

	/* get the file size back from the server */
	ret = recv(sock, cfsize, sizeof(cfsize), 0);
	if (ret == -1) {
		perror("recv()");
		fprintf(stderr, "recv failed\n");
		exit(1);
	}
	fsize = atoi(cfsize);
	fprintf(stderr, "file size is %d bytes\n", fsize);

	/* open the output file */
	outf = fopen(fname, "w");
	if (!outf) {
		perror("fopen()");
		fprintf(stderr, "file open failed\n");
	}

	/* receive the incoming data and write it to the output file */
	while (count < fsize) {
		ret = recv(sock, buf, sizeof(buf), MSG_DONTWAIT);
		if (ret == -1) {
			perror("recv()");
			fprintf(stderr, "recv failed\n");
		}

		if (ret > 0) {
			fwrite(buf, sizeof(char), (size_t) ret, outf);
			fprintf(stderr, "received %d bytes\n", ret);
		}

		prev = count;
		count += ret;
		if (prev == count) {
			fprintf(stderr, "error: expected %d, received %d\n",
				fsize, count);
			exit(1);
		}
	}
	fclose(outf);
	exit(0);
}