리눅스에서 간단한 파일전송 프로그램 만들기

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
 
#define BUFSIZE 4096
 
void err_quit(char *msg) {
	fputs(msg, stderr);
	fputc('\n', stderr);
	exit(1);
}
 
int recvn(int s, char *buf, int len) {
	int received;
	char *ptr = buf;
	int left = len;
 
	while(left > 0) {
		received = read(s, buf, sizeof(buf));
		if(received == -1)
			return -1;
		else if(received == 0)
			break;
		left -= received;
		ptr += received;
	}
 
	return (len - left);
}
 
 
int main(int argc, char *argv[])
{
	int retval;
 
	int listen_sock = socket(PF_INET, SOCK_STREAM, 0);
	if(listen_sock == -1)
		err_quit("socket() error");
 
	struct sockaddr_in serveraddr;
	memset(&serveraddr, 0, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_port = htons(9000);
	serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
	retval = bind(listen_sock, (struct sockaddr*) &serveraddr, sizeof(serveraddr));
	if(retval == -1)
		err_quit("bind() error");
 
	retval = listen(listen_sock, 5);
	if(retval == -1)
		err_quit("listen() error");
 
	int client_sock;
	struct sockaddr_in clientaddr;
	int addrlen;
	char buf[BUFSIZE];
 
	while(1) {
		addrlen = sizeof(clientaddr);
		client_sock = accept(listen_sock, (struct sockaddr*) &clientaddr, &addrlen);
		if(client_sock == -1)
			err_quit("accept() error");
 
		printf("\n->FileSender connect : IP = %s, Port = %d\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
 
		char filename[256];
		memset(filename, 0, sizeof(filename));
		retval = recvn(client_sock, filename, 256);
		if(retval == -1) {
			err_quit("recv() error");
			close(client_sock);
			continue;
		}
		printf("-> filename : %s\n", filename);
 
		int totalbytes;
		retval = recvn(client_sock, (char *) &totalbytes, sizeof(totalbytes));
		if(retval == -1) {
			err_quit("recv() error");
			close(client_sock);
			continue;
		}
		printf("-> filesize : %d\n", totalbytes);
 
		FILE *fp = fopen(filename, "wb");
		if(fp == NULL) {
			err_quit("File I/O error");
			close(client_sock);
			continue;
		}
 
		int numtotal = 0;
		while(1) {
			retval = recvn(client_sock, buf, BUFSIZE);
			if(retval == -1) {
				err_quit("recv() error");
				break;
			}
			else if(retval == 0)
				break;
			else {
				fwrite(buf, 1, retval, fp);
				numtotal += retval;
			}
		}
		fclose(fp);
 
		if(numtotal == totalbytes)
			printf("-> File trans complete\n");
		else
			printf("-> File trans failed\n");
 
		close(client_sock);
		printf("FileSender complete : IP = %s, Port = %d\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
 
	}
 
	close(listen_sock);
 
	return 0;
 
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
 
#define BUFSIZE 4096
 
void err_quit(char *msg) {
	fputs(msg, stderr);
	fputc('\n', stderr);
	exit(1);
	}
 
int main(int argc, char *argv[])
{
	int retval;
 
	if(argc < 2) {
		fprintf(stderr, "Usage : %s [Filename] \n", argv[0]);
		return -1;
	}
 
	int sock;
	struct sockaddr_in serveraddr;
 
	sock = socket(PF_INET, SOCK_STREAM, 0);
	if(sock == -1)
		err_quit("socket() error");
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_port = htons(9000);
	serveraddr.sin_addr.s_addr = htonl(INADDR_ANY); /*inet_addr("127.0.0.1");*/
	retval = connect(sock, (struct sockaddr*) &serveraddr, sizeof(serveraddr));
	if(retval == -1)
		err_quit("connect() error");
 
	FILE *fp = fopen(argv[1], "rb");
	if(fp == NULL) 
		err_quit("fopen() error");
 
	char filename[256];
	memset(filename, 0, sizeof(filename));
	sprintf(filename, argv[1]);
	retval = write(sock, filename, sizeof(filename));
	if(retval == -1)
		err_quit("write() error");
 
	fseek(fp, 0, SEEK_END);
	int totalbytes = ftell(fp);
 
	retval = write(sock, (char *)&totalbytes, sizeof(totalbytes));
	if(retval == -1)
		err_quit("write() error");
 
	char buf[BUFSIZE];
	int numread;
	int numtotal = 0;
 
	rewind(fp);
	while(1) {
		numread = fread(buf, 1, BUFSIZE, fp);
		if(numread > 0) {
			retval = write(sock, buf, numread);
			if(retval == -1)
				err_quit("write() error!");
			numtotal += numread;
		}
		else if(numread == 0 && numtotal == totalbytes) {
			printf("file trans complete : %d bytes\n", numtotal);
			break;
		}
		else {
			err_quit("file I/O error");
		}
	}
	fclose(fp);
 
	close(sock);
 
	return 0;
}