C语言之Ftp工具的简单实现

这是一个简易版的ftp工具，主要实现的功能有ls、pwd、exit、help、put、get。

实例图哦：

下边是代码：
server.c

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

#define NUM 100 
#define PORT 8000

int command_ls(int cli_sockfd);
int command_pwd(int cli_sockfd);
int command_get(int cli_sockfd, char *filename);
int command_put(int cli_sockfd, char *filename);

int main(int argc, char *argv[])
{
    int ser_sockfd = 0;
    int cli_sockfd = 0;

    struct sockaddr_in ser_addr, cli_addr;
    int ser_len = 0;
    int cli_len = 0;

    char command[NUM];
    char buffer[NUM];
    bzero(buffer, NUM);
    bzero(command, NUM);

    if((ser_sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
    	perror("socket error!");
	return -1;
    }

    bzero(&ser_addr, sizeof(ser_addr));
    ser_addr.sin_family = AF_INET;
    ser_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    ser_addr.sin_port = htons(PORT);
    ser_len = sizeof(ser_addr);

    if((bind(ser_sockfd, (struct sockaddr *)&ser_addr, ser_len)) < 0){
    	perror("bind error!");
	return -1;
    }

    if(listen(ser_sockfd, 5) < 0){
    	perror("listen error!");
	return -1;
    }

    cli_len = sizeof(cli_addr);
    bzero(&cli_addr, sizeof(cli_len));

    while(1){
	if((cli_sockfd = accept(ser_sockfd, (struct sockaddr *)&cli_addr, &cli_len)) < 0){
	    perror("accept error!");
      	    return -1;
	}
	if(read(cli_sockfd, command, NUM) < 0){
	    perror("read error!");
	    return -1;
	}
	printf("command is :%s\n", command);
  
        if(strncm