[FTP] (2) 클라이언트 구현하기

네트워크로그 2011. 3. 9. 02:22



다음은 c언어로 구현한  open, get, put, ls, cd, pwd, quit/bye, hash 명령을  구현한 간단한 FTP 클라이언트 예제이다. 

에러처리와 소켓의 recv, send 함수의 동작방식을 정확히 고려하지 않았기 때문에, 정확히 동작하지 않을 수 있다.   

데이터 수신시 하나의 명령에 대한 메시지의 끝을 구분해 줄 수 있는 방법이 추가로 필요하다. 

(메시지 끝을 의미하는 \r\n 로 구분)




FtpCommand.h

 : Ftp 커맨드 및 상수를  정의한 헤더파일 

#define CMD_OPEN "open"
#define CMD_LIST "ls"
#define CMD_GET "get"
#define CMD_PUT "put"
#define CMD_PWD "pwd"
#define CMD_CD "cd"
#define CMD_QUIT "quit"
#define CMD_BYE "bye"
#define CMD_HASH "hash"
#define CMD_SHELL "!"

#define MODE_DEBUG 1
#define MODE_NORMAL 0

#define FTP_PORT 21

extern int mode;

void debug(char *msg) {
        if (mode == MODE_DEBUG) {
                printf("[debug] : %s \n", msg);
        }
}



ClientSocket.h

: Ftp Client 구현 파일로 단일 프로세스만을 사용하였음 

#include <sys/types.h>
#include <sys/socket.h> 
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h> 
#include <sys/types.h> 
#include <sys/stat.h>
#include <fcntl.h>

#define TEMP_BUFFER_SIZE 1024

int connectServer(char *serverIp, short port) {
        int sock;
        struct sockaddr_in servAddr;
        
        if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
                perror("sock failed");
                exit(1);
        }
        
        memset(&servAddr, 0, sizeof(servAddr));
        servAddr.sin_family = AF_INET;
        servAddr.sin_addr.s_addr = inet_addr(serverIp);
        servAddr.sin_port = htons(port);
        
        if (connect(sock, (struct sockaddr*)&servAddr, sizeof(servAddr)) == -1) {
                perror("connect failed");
                exit(1);
        }
        
        return sock;
}


void sendProtocol(int sock, char *protocol) {
        if (send(sock, protocol, strlen(protocol), 0) != strlen(protocol)) {
                perror("send failed");
                exit(1);
        }
	if (MODE_DEBUG == mode) {
		printf("send: %s", protocol);
	}
}

void recvProtocol(int sock, char *recvBuffer, int bufferSize) {
        int recvLen;
        
        if ((recvLen = recv(sock, recvBuffer, bufferSize-1, 0)) <= 0) {
                perror("recv failed");
                exit(1);
        }
        recvBuffer[recvLen] = '\0';

	if (MODE_DEBUG == mode) {
		printf("recv: %s", recvBuffer);
	}
}


unsigned int downloadFile(int sock, char *filePath, unsigned int fileSize, int hashFlag) {
        char readBuffer[TEMP_BUFFER_SIZE];
        unsigned int readBytes, totalBytes, numHash;
        
        int fd = open(filePath, O_WRONLY | O_CREAT, 0744);
        
        totalBytes = numHash = 0;
        while (totalBytes < fileSize) {
                if ((readBytes = read(sock, readBuffer, TEMP_BUFFER_SIZE)) <= 0) {
                        close(fd);
                        return totalBytes;
                }
                write(fd, readBuffer, readBytes);
                totalBytes += readBytes;
                
                if (hashFlag) {
                        if ((totalBytes/TEMP_BUFFER_SIZE) > numHash) {
                                numHash++;
                                printf("#");
                        }
                }
        }
        close(fd);
        printf("\n");
        
        return totalBytes;
}

unsigned int uploadFile(int sock, char *filePath, int hashFlag) {
        char readBuffer[TEMP_BUFFER_SIZE];
        unsigned int readBytes, totalBytes, numHash;
        
        int fd = open(filePath, O_RDONLY);
        
        totalBytes = numHash = 0;
        while ((readBytes = read(fd, readBuffer, TEMP_BUFFER_SIZE)) > 0) {
                write(sock, readBuffer, readBytes);
                totalBytes += readBytes;
                
                if (hashFlag) {
                        if ((totalBytes/TEMP_BUFFER_SIZE) > numHash) {
                                numHash++;
                                printf("#");
                        }
                }
        }
        close(fd);
        printf("\n");
        
        return totalBytes;
}



FtpClient.c

:  Ftp Client 구현 파일로 단일 프로세스만을 사용하였음

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

#define COMMAND_MAX_SIZE 1024
#define BUFFER_SIZE 1024
#define FILENAME_SIZE 256
#define END_OF_PROTOCOL "\r\n"

void initializeFtpClient();
void startFtpClient(char *ip, char *port);
void commandHandle(char *cmd); 
void defaultHandler(char *cmd);
int modeCheck(const char *option);
void printMessage(char *msg);

void openCon(char *cmd);
void list(char *listCmd);
void get(char *getCmd);
void put(char *putCmd);
void cd(char *cdCmd);
void quit(char *quitCmd);
void pwd(char *pwdCmd);
void bye(char *byeCmd);
void hash(char *hashCmd);
void passiveMode(char *ip, int *port);
void shellEscape(char *shellCmd);

unsigned int downloadFile(int sock, char *filePath, unsigned int fileSize, int hashFlag);
unsigned int uploadFile(int sock, char *filePath, int hashFlag);


typedef struct _FtpCmdHandler {
        char cmd[5];
        void (*handler)(char* arg);
        
} FtpCmdHandler;

// Map Ftp Command to Handler
FtpCmdHandler ftpCmdHandler[] = {
        { CMD_OPEN, openCon },
        { CMD_LIST, list },
        { CMD_PUT, put },
        { CMD_GET, get },
        { CMD_CD, cd },
        { CMD_PWD, pwd },
        { CMD_HASH, hash },
        { CMD_QUIT, quit },
        { CMD_BYE, bye },
        { CMD_SHELL, shellEscape },
        
};

// sock - PI socket ,  dtpSock - DTP socket
int sock, dtpSock;
int state;      
int mode;
int hashFlag;


int main (int argc, char const *argv[])
{
 	if (argc == 3) {
	// argv[1] == ip, argv[2] == port
		startFtpClient(argv[1], argv[2]);
	} else if (argc == 4 && modeCheck(argv[1]) == MODE_DEBUG) {
	// argv[1] == -d, argv[2] = ip, argv[3] == port
		startFtpClient(argv[2], argv[3]);
	}  else {
		fprintf(stderr, "Usage: %s [-d]  \n", argv[0]);
	}
                
        return 0;
}

int modeCheck(const char *option) {
        if (!strcmp(option, "-d")) {
                // debug mode
                mode = MODE_DEBUG;
        } else {
                mode = MODE_NORMAL;
        }
        return mode;
}

// initialize ftp client
void initializeFtpClient() {
        hashFlag = 1;
        state = INITIAL_STATE;  
        debug("initialized");
}



// ftp client start 
void startFtpClient(char *ip, char *port) {   
        char cmd[COMMAND_MAX_SIZE];

        initializeFtpClient();
        
        while (1) { 
                // input user command
                if (ip == 0 && port == 0) {
                        printMessage("ftp>");
                        fgets(cmd, COMMAND_MAX_SIZE, stdin);
                } else {
                        sprintf(cmd, "open %s %s", ip, port);
                        startCmd = 0;
                }       
                // call handler 
                commandHandle(cmd);
        }

}

// map command to handler 
void commandHandle(char *cmd) {
        int i;
        int numCmd = sizeof(ftpCmdHandler)/sizeof(FtpCmdHandler);
        
        for (i = 0; i < numCmd; i++) {
                if (!strncmp(cmd, ftpCmdHandler[i].cmd, strlen(ftpCmdHandler[i].cmd))) {
                        (*(ftpCmdHandler[i].handler))(cmd);
                        break;
                }
        }       
}


void defaultHandler(char *cmd) {
        printf("default handler: %s\n", cmd);
}

// ftp server connect 
void openCon(char *openCmd) {
        char serverIp[16], serverPort[16];
        char cmd[BUFFER_SIZE];
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        
        sscanf(openCmd,"%*s %s %s%*c", serverIp, serverPort);
        debug(serverIp);
        
        // connect to server
        sock = connectServer(serverIp, atoi(serverPort));
        recvProtocol(sock, recvBuffer, BUFFER_SIZE-1);
        
        // send user name
        printf("Name: ");
        fgets(cmd, COMMAND_MAX_SIZE, stdin);
        sprintf(sendBuffer, "User %s", cmd);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE-1);
        printMessage(recvBuffer);

        // send password
        printf("Password: ");
        fgets(cmd, COMMAND_MAX_SIZE, stdin);
        sprintf(sendBuffer, "PASS %s", cmd);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE-1);
        printMessage(recvBuffer);
                
        // get server os information    
        sprintf(sendBuffer, "SYST%s", END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE-1);
        printMessage(recvBuffer);

}


// send EPSV or PASS to Server
void passiveMode(char *ip, int *port) {
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        int host0, host1, host2, host3;
        int port0, port1;
        
        sprintf(sendBuffer, "PASV%s", END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE-1);
        printMessage(recvBuffer);
        
        sscanf(strchr(recvBuffer, '(')+1, "%d,%d,%d,%d,%d,%d", &host0, &host1, &host2, &host3, &port0, &port1);
        sprintf(ip, "%d.%d.%d.%d", host0, host1, host2, host3);

        *port = port0*256 + port1;
        
        debug(ip);
        printf("dtp port : %d\n", *port);
}


// get remote working directory file list
void list(char *listCmd) {
        int port;
        char ip[16];
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE*8];
        
        debug("list");

        // recv server response and parsing 
        passiveMode(ip, &port);
        
        // connect to DTP  
        dtpSock = connectServer(ip, port);
        
        // send LIST command to PI server
        sprintf(sendBuffer, "LIST%s", END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        // recv file list from DTP
        recvProtocol(dtpSock, recvBuffer, BUFFER_SIZE*8);
        printMessage(recvBuffer);
        
        // recv complete message from PI server
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        close(dtpSock);
}


// file download
void get(char *getCmd) {
        int port;
        unsigned int fileSize;
        char ip[16], filePath[FILENAME_SIZE], fileName[50];
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        
        // get local current working directory 
        getcwd(filePath, FILENAME_SIZE);
        sscanf(getCmd, "%*s %s%*c", fileName);
        sprintf(filePath, "%s/%s", filePath, fileName);

        debug("get");
        printf("fileName: %s\n", fileName);
        printf("filePath: %s\n", filePath);

        passiveMode(ip, &port);
        
        // connect to DTP
        dtpSock = connectServer(ip, port);
        
        // request server for transfer start - RETR fileName
        sprintf(sendBuffer, "RETR %s%s", fileName, END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        // extract fileSize 
        sscanf(strchr(recvBuffer, '(')+1, "%u", &fileSize);
        printf("fileSize: %u\n", fileSize);
        
        // download file from DTP 
        downloadFile(dtpSock, filePath, fileSize, hashFlag);
        
        // recv complete message from PI server
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        close(dtpSock);
}




// file upload
void put(char *putCmd) {
        int port;
        unsigned int fileSize;
        char ip[16], filePath[FILENAME_SIZE], fileName[50];
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        
        sscanf(putCmd, "%*s %s%*c", fileName);
        
        // get local current working directory
        getcwd(filePath, FILENAME_SIZE);
        sscanf(putCmd, "%*s %s%*c", fileName);
        sprintf(filePath, "%s/%s", filePath, fileName);

        debug("put");
        debug(filePath);
        
        passiveMode(ip, &port);
        
        // connect to DTP
        dtpSock = connectServer(ip, port);
        
        // request server for transfer start - STOR fileName
        sprintf(sendBuffer, "STOR %s%s", fileName, END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        // file upload to DTP 
        fileSize = uploadFile(dtpSock, filePath, hashFlag);
        
        close(dtpSock);
        
        /// recv complete message from PI server
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
}


// change remote working directory
void cd(char *cdCmd) {
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        debug("cd");

        sscanf(cdCmd, "%*s %s%*c", recvBuffer);
        debug(recvBuffer);

        sprintf(sendBuffer, "CWD %s%s", recvBuffer, END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
}

// ftp client exit 
void quit(char *quitCmd) {
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        debug("quit");
        
        sprintf(sendBuffer, "QUIT%s", END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
        
        close(sock);
        exit(0);
}

// same quit  
void bye(char *byeCmd) {
        quit(0);
}

// get remote working directory
void pwd(char *pwdCmd) {
        char sendBuffer[BUFFER_SIZE];
        char recvBuffer[BUFFER_SIZE];
        debug("pwd");
        
        sprintf(sendBuffer, "PWD%s", END_OF_PROTOCOL);
        sendProtocol(sock, sendBuffer);
        recvProtocol(sock, recvBuffer, BUFFER_SIZE);
        printMessage(recvBuffer);
}


// hash option on/off
void hash(char *hashCmd) {
        debug("hash");
        hashFlag = !hashFlag;
        
        if (hashFlag == 0) {
                printMessage("hash off");
        } else {
                printMessage("hash on");
        }
}

// shell command - not implemented
void shellEscape(char *shellCmd) {
        printMessage("not implemented");
}



void printMessage(char *msg) {
        printf("%s", msg);
}





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