最近在做一個(gè)FTP客戶端項(xiàng)目，項(xiàng)目開(kāi)始是基于CFReadStreamCreateWithFTPURL系列方法的第三方實(shí)現(xiàn)的。但是在用CFFTP方法遇到了一個(gè)問(wèn)題，背景如下：
傳輸模式采用被動(dòng)模式，F(xiàn)TP服務(wù)器位于路由器后面，做好端口映射后，在公網(wǎng)訪問(wèn)FTP服務(wù)器發(fā)送PASV指令時(shí)，服務(wù)器返回了內(nèi)網(wǎng)IP地址，CFFTP報(bào)錯(cuò)。按理說(shuō)這應(yīng)該是服務(wù)器配置的問(wèn)題，但是PC、安卓卻能夠完成傳輸，然后領(lǐng)導(dǎo)讓我自己解決。那么問(wèn)題來(lái)了，CFFTP你就不能用command的ip來(lái)給data socket連一下？

圖1.png

然后就打算自己實(shí)現(xiàn)FTP網(wǎng)絡(luò)方法了。FTP文件傳輸協(xié)議是基于TCP的，屬于分層網(wǎng)絡(luò)協(xié)議中的應(yīng)用層。

#import <Foundation/Foundation.h>

@interface YHHFtpRequest : NSObject

@property (nonatomic, strong) NSString *ftpUser;
@property (nonatomic, strong) NSString *ftpPassword;
@property (nonatomic, strong) NSString *serversPath; // 服務(wù)器文件全路徑，如:(ftp://xx.xx.xx.xx:21/XXX/xx.jpg) (ftp://) 可以略
@property (nonatomic, strong) NSString *localPath; // 本地文件全路徑

- (void)download:(BOOL)resume
 progress:(void(^)(Float32 percent, NSUInteger finishSize))progress
 complete:(void(^)(id respond, NSError *error))complete;

- (void)upload:(BOOL)resume
 progress:(void(^)(Float32 percent, NSUInteger finishSize))progress
 complete:(void(^)(id respond, NSError *error))complete;

- (void)list:(void(^)(id respond, NSError *error))complete;
- (void)createDirctory:(NSString *)name complete:(void(^)(id respond, NSError *error))complete;
- (void)deleteDirctory:(NSString *)name complete:(void(^)(id respond, NSError *error))complete;
- (void)deleteFile:(NSString *)name complete:(void(^)(id respond, NSError *error))complete;
- (void)rename:(NSString *)newName complete:(void(^)(id respond, NSError *error))complete;

@end

主要需要實(shí)現(xiàn)的功能接口就這些

我這邊主要采用被動(dòng)模式的連接方式，所以就主要研究了下被動(dòng)模式相關(guān)的知識(shí)：
1.命令端口：我這邊采用的是CFStream流來(lái)收發(fā)信息的。

- (void)setupCommandSocket {
    CFStreamClientContext context = {0, (__bridge void *)self, NULL, NULL, NULL};
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
    
    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef)_host, _port, &readStream, &writeStream);
    //這里我只需要管收到的消息，所以就只給readStream設(shè)置了回調(diào)
    CFReadStreamSetClient(readStream, kCFStreamEventHasBytesAvailable|kCFStreamEventErrorOccurred|kCFStreamEventEndEncountered, ReadStreamClientCallBack, &context);
    
    CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
    CFWriteStreamScheduleWithRunLoop(writeStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
    
    _read = readStream;
    _write = writeStream;
    
    CFReadStreamOpen(readStream);
    CFWriteStreamOpen(writeStream);
}

這里采用CFStream是因?yàn)镾tream流獲取信息方便，也能夠簡(jiǎn)單的通過(guò)CFStreamEventType得到流的狀態(tài)。也不用不像CFSocket要多加幾個(gè)頭文件。
2.數(shù)據(jù)端口：

- (void)setupDataSocket:(NSString *)ip {
    NSArray *arr = [ip componentsSeparatedByString:@":"];
    
    NSString *host = arr.firstObject;
    UInt32 port = [arr.lastObject intValue];
    
    NSInputStream *input;
    NSOutputStream *output;
    
    if (_ctype >= OperateUpload) {  //上傳
        [NSStream getStreamsToHostWithName:host port:port inputStream:nil outputStream:&output];
        input = [NSInputStream inputStreamWithFileAtPath:_localPath];
        [input setProperty:@(_location) forKey:NSStreamFileCurrentOffsetKey];
        //        _handle = [NSFileHandle fileHandleForReadingAtPath:_localPath];
        //        [_handle seekToFileOffset:_location];
    }else {
        [NSStream getStreamsToHostWithName:host port:port inputStream:&input outputStream:nil];
        output = [NSOutputStream outputStreamToFileAtPath:_localPath append:(_ctype == OperateDownloadResume)];
    }
    
    input.delegate = self;
    output.delegate = self;
    
 
    [input scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    [output scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    
    _input = input;
    _output = output;
    
    [_output open];
    //    [_input open];
}

這里在上傳文件的時(shí)候需要支持?jǐn)帱c(diǎn)續(xù)傳，開(kāi)始的時(shí)候沒(méi)找到NSStream設(shè)置偏移量的方法，所以采用的NSFileHandle來(lái)獲取數(shù)據(jù)，這里通過(guò)NSStream或者NSFileHandle來(lái)讀取本地文件都是可以的。

FTP要完成一個(gè)文件操作時(shí)，需要發(fā)送一系列的指令；具體需要發(fā)送哪些命令可以使用其他FTP客戶端(FileZiIla)查看。
這里拿上傳舉例：

登錄(USER)->密碼(PASS)->指定目錄(CWD)->設(shè)置數(shù)據(jù)格式(TYPE)->獲取文件大小(SIZE)->設(shè)置被動(dòng)模式(PASV)->上傳(APPE／STOR)

每一個(gè)操作都要等前面一個(gè)指令得到正確的響應(yīng)后才能進(jìn)行。我這里考慮的方法是把完成一個(gè)操作的所有命令做成枚舉加到一個(gè)數(shù)組里面，要做什么操作就拿對(duì)應(yīng)數(shù)組遍歷。

typedef NS_ENUM(NSInteger, OperateType) {
    OperateCreateD,
    OperateDeleteD,
    OperateDelete,
    OperateRename,
    OperateList,
    OperateDownload,
    OperateDownloadResume,
    OperateUpload,
    OperateUploadResume
};
#define OPERATIONS                  @[OPERATION_CREATE_D, OPERATION_DELETE_D, OPERATION_DELETE, OPERATION_RENAME, OPERATION_LIST, OPERATION_DOWNLOAD, OPERATION_DOWNLOAD_RESUME, OPERATION_UPLOAD, OPERATION_UPLOAD_RESUME]

#define OPERATION_LOGIN             @[@(SendUser), @(SendPASS)]
#define OPERATION_CREATE_D          @[@(SendCWD),  @(SendMKD)]      //創(chuàng)建目錄
#define OPERATION_DELETE_D          @[@(SendCWD),  @(SendRMD)]      //刪除目錄
#define OPERATION_DELETE            @[@(SendCWD),  @(SendDELE)]
#define OPERATION_RENAME            @[@(SendRNFR), @(SendRNTO)]
#define OPERATION_LIST              @[@(SendCWD),  @(SendType), @(SendPASV), @(SendMLSD)]
#define OPERATION_DOWNLOAD          @[@(SendCWD),  @(SendType), @(SendSize), @(SendPASV), @(SendRETR)]
#define OPERATION_DOWNLOAD_RESUME   @[@(SendCWD),  @(SendType), @(SendSize), @(SendPASV), @(SendREST), @(SendRETR)]
#define OPERATION_UPLOAD            @[@(SendCWD),  @(SendType), @(SendPASV), @(SendSTOR)]
#define OPERATION_UPLOAD_RESUME     @[@(SendCWD),  @(SendType), @(SendSize), @(SendPASV), @(SendAPPE)]

這里把文件操作做成了枚舉類型，F(xiàn)TP指令也是枚舉類型，發(fā)送指令時(shí)通過(guò)調(diào)用方法- (void)send:(SendMessage)smsg來(lái)獲取完成發(fā)送操作

- (BOOL)login {
    
    NSArray *operations = OPERATION_LOGIN;
    if (!_semaphore) {
        _semaphore = dispatch_semaphore_create(0);
    }
    
    // 加在在主線程的原因是需要添加到runloop，最好是可以開(kāi)個(gè)子線程，啟動(dòng)該線程的runloop。
    dispatch_async(dispatch_get_main_queue(), ^{
        [self setupCommandSocket];
    });
    // 等待commandSocket連接到服務(wù)器，接收歡迎消息
    NSLog(@"等待");
    long res = dispatch_semaphore_wait(_semaphore, dispatch_time(DISPATCH_TIME_NOW, 200*NSEC_PER_SEC));
    // 如果由dispatch_semaphore_signal激發(fā) res==0
    if (res != 0 || _failure) {
        NSLog(@"connect error");
        return NO;
    }
    
    // 登陸操作
    for (int i = 0; i < operations.count; i++) {
        SendMessage sendm = [operations[i] integerValue];
        [self send:sendm];
        
        NSLog(@"等待");
        long res = dispatch_semaphore_wait(_semaphore, dispatch_time(DISPATCH_TIME_NOW, 20*NSEC_PER_SEC));
        // 如果由dispatch_semaphore_signal激發(fā) res==0
        if (res != 0 || _failure) {
            NSLog(@"error");
            return NO;
        }
    }
    //    return _isLogin;
    return YES;
}
- (void)yhh_operate:(OperateType)operate {
    NSArray *operations = OPERATIONS[operate];
    
    if (!_isLogin) {
        if (!(_isLogin = [self login])) {
            NSLog(@"login error");
            return;
        }
    }
    // 如果登錄失敗，不繼續(xù)執(zhí)行下面的命令
    if (!_isLogin)
        return;
    
    for (int i = 0; i < operations.count; i++) {
        SendMessage sendm = [operations[i] integerValue];
        // 設(shè)置過(guò)Type就跳過(guò)
        if (sendm==SendType && _isType==YES) {
            continue;
        }
        // 發(fā)送操作
        [self send:sendm];
        // 等待響應(yīng)
        NSLog(@"等待");
        long res = dispatch_semaphore_wait(_semaphore, dispatch_time(DISPATCH_TIME_NOW, 20*NSEC_PER_SEC));
        if (res != 0 || _failure) {
            // error
            _failure = NO;
            break;
        }
    }
}

還有一些對(duì)服務(wù)器響應(yīng)的處理代碼，我直接把代碼鏈接貼出來(lái)可以交流學(xué)習(xí)一下。
下載鏈接