NSURLSession 和亚马逊 S3 上传 [英] NSURLSession and amazon S3 uploads
问题描述
我有一个应用程序，目前正在将图像上传到亚马逊 S3.我一直在尝试将其从使用 NSURLConnection 切换到 NSURLSession，以便在应用程序处于后台时可以继续上传！我似乎遇到了一些问题.NSURLRequest 被创建并传递给 NSURLSession，但亚马逊发回 403 - 禁止响应，如果我将相同的请求传递给 NSURLConnection，它会完美地上传文件.
I have an app which is currently uploading images to amazon S3. I have been trying to switch it from using NSURLConnection to NSURLSession so that the uploads can continue while the app is in the background! I seem to be hitting a bit of an issue. The NSURLRequest is created and passed to the NSURLSession but amazon sends back a 403 - forbidden response, if I pass the same request to a NSURLConnection it uploads the file perfectly.
这是创建响应的代码:
NSString *requestURLString = [NSString stringWithFormat:@"http://%@.%@/%@/%@", BUCKET_NAME, AWS_HOST, DIRECTORY_NAME, filename];
NSURL *requestURL = [NSURL URLWithString:requestURLString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:requestURL
cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData
timeoutInterval:60.0];
// Configure request
[request setHTTPMethod:@"PUT"];
[request setValue:[NSString stringWithFormat:@"%@.%@", BUCKET_NAME, AWS_HOST] forHTTPHeaderField:@"Host"];
[request setValue:[self formattedDateString] forHTTPHeaderField:@"Date"];
[request setValue:@"public-read" forHTTPHeaderField:@"x-amz-acl"];
[request setHTTPBody:imageData];
然后这标志着响应(我认为这来自另一个 SO 答案):
And then this signs the response (I think this came from another SO answer):
NSString *contentMd5 = [request valueForHTTPHeaderField:@"Content-MD5"];
NSString *contentType = [request valueForHTTPHeaderField:@"Content-Type"];
NSString *timestamp = [request valueForHTTPHeaderField:@"Date"];
if (nil == contentMd5) contentMd5 = @"";
if (nil == contentType) contentType = @"";
NSMutableString *canonicalizedAmzHeaders = [NSMutableString string];
NSArray *sortedHeaders = [[[request allHTTPHeaderFields] allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
for (id key in sortedHeaders)
{
NSString *keyName = [(NSString *)key lowercaseString];
if ([keyName hasPrefix:@"x-amz-"]){
[canonicalizedAmzHeaders appendFormat:@"%@:%@
", keyName, [request valueForHTTPHeaderField:(NSString *)key]];
}
}
NSString *bucket = @"";
NSString *path = request.URL.path;
NSString *query = request.URL.query;
NSString *host = [request valueForHTTPHeaderField:@"Host"];
if (![host isEqualToString:@"s3.amazonaws.com"]) {
bucket = [host substringToIndex:[host rangeOfString:@".s3.amazonaws.com"].location];
}
NSString* canonicalizedResource;
if (nil == path || path.length < 1) {
if ( nil == bucket || bucket.length < 1 ) {
canonicalizedResource = @"/";
}
else {
canonicalizedResource = [NSString stringWithFormat:@"/%@/", bucket];
}
}
else {
canonicalizedResource = [NSString stringWithFormat:@"/%@%@", bucket, path];
}
if (query != nil && [query length] > 0) {
canonicalizedResource = [canonicalizedResource stringByAppendingFormat:@"?%@", query];
}
NSString* stringToSign = [NSString stringWithFormat:@"%@
%@
%@
%@
%@%@", [request HTTPMethod], contentMd5, contentType, timestamp, canonicalizedAmzHeaders, canonicalizedResource];
NSString *signature = [self signatureForString:stringToSign];
[request setValue:[NSString stringWithFormat:@"AWS %@:%@", self.S3AccessKey, signature] forHTTPHeaderField:@"Authorization"];
那么如果我使用这行代码:
Then if I use this line of code:
[NSURLConnection connectionWithRequest:request delegate:self];
它可以工作并上传文件，但如果我使用:
It works and uploads the file, but if I use:
NSURLSessionUploadTask *task = [self.session uploadTaskWithRequest:request fromFile:[NSURL fileURLWithPath:filePath]];
[task resume];
我收到了禁止的错误..！?
I get the forbidden error..!?
有没有人试过用这个上传到 S3 并遇到类似的问题?我想知道这是否与会话暂停和恢复上传的方式有关，或者它对请求做了一些有趣的事情..?
Has anyone tried uploading to S3 with this and hit similar issues? I wonder if it is to do with the way the session pauses and resumes uploads, or it is doing something funny to the request..?
一种可能的解决方案是将文件上传到我控制的临时服务器，并在完成后将其转发到 S3...但这显然不是理想的解决方案！
One possible solution would be to upload the file to an interim server that I control and have that forward it to S3 when it is complete... but this is clearly not an ideal solution!
非常感谢任何帮助！！
谢谢！
推荐答案
我根据 Zeev Vax 的回答使其工作.我想就我遇到的问题提供一些见解并提供一些小的改进.
I made it work based on Zeev Vax answer. I want to provide some insight on problems I ran into and offer minor improvements.
构建一个普通的 PutRequest，例如
Build a normal PutRequest, for instance
S3PutObjectRequest* putRequest = [[S3PutObjectRequest alloc] initWithKey:keyName inBucket:bucketName];
putRequest.credentials = credentials;
putRequest.filename = theFilePath;
现在我们需要做一些S3Client通常为我们做的工作
Now we need to do some work the S3Client usually does for us
// set the endpoint, so it is not null
putRequest.endpoint = s3Client.endpoint;
// if you are using session based authentication, otherwise leave it out
putRequest.securityToken = messageTokenDTO.securityToken;
// sign the request (also computes md5 checksums etc.)
NSMutableURLRequest *request = [s3Client signS3Request:putRequest];
现在将所有这些复制到一个新的请求中.亚马逊使用自己的 NSUrlRequest 类会导致异常
Now copy all of that to a new request. Amazon use their own NSUrlRequest class which would cause an exception
NSMutableURLRequest* request2 = [[NSMutableURLRequest alloc]initWithURL:request.URL];
[request2 setHTTPMethod:request.HTTPMethod];
[request2 setAllHTTPHeaderFields:[request allHTTPHeaderFields]];
现在我们可以开始实际传输
Now we can start the actual transfer
NSURLSession* backgroundSession = [self backgroundSession];
_uploadTask = [backgroundSession uploadTaskWithRequest:request2 fromFile:[NSURL fileURLWithPath:theFilePath]];
[_uploadTask resume];
这是创建后台会话的代码:
This is the code that creates the background session:
- (NSURLSession *)backgroundSession {
static NSURLSession *session = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfiguration:@"com.example.my.unique.id"];
session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
});
return session;
}
我花了一段时间才弄清楚会话/任务委托需要处理身份验证挑战(我们实际上是对 s3 进行身份验证).所以只要执行
It took me a while to figure out that the session / task delegate needs to handle an auth challenge (we are in fact authentication to s3). So just implement
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler {
NSLog(@"session did receive challenge");
completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
}
这篇关于NSURLSession 和亚马逊 S3 上传的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
