Synchonous SSL certificate handling on iPhone - iphone

Question

I was wondering if anyone can help me understand how to add SSL certificate handling to synchronous
connections to a https service.
I know how to do this with asynchronous connections but not synchronous.
NSString *URLpath = #"https://mydomain.com/";
NSURL *myURL = [[NSURL alloc] initWithString:URLpath];
NSMutableURLRequest *myURLRequest = [NSMutableURLRequest requestWithURL:myURL cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];
[myURL release];
[myURLRequest setHTTPMethod:#"POST"];
NSString *httpBodystr = #"setting1=1";
[myURLRequest setHTTPBody:[httpBodystr dataUsingEncoding:NSUTF8StringEncoding]];
NSHTTPURLResponse* myURLResponse;
NSError* myError;
NSData* myDataResult = [NSURLConnection sendSynchronousRequest:myURLRequest returningResponse:&myURLResponse error:&myError];
//I guess I am meant to put some SSL handling code here
Thank you.

Answer 1

Using the static sendSynchronousRequest function is not posible, but i found an alternative.
First of all NSURLConnectionDataDelegate object like this one
FailCertificateDelegate.h
#interface FailCertificateDelegate : NSObject <NSURLConnectionDataDelegate>
#property(atomic,retain)NSCondition *downloaded;
#property(nonatomic,retain)NSData *dataDownloaded;
-(NSData *)getData;
#end
FailCertificateDelegate.m
#import "FailCertificateDelegate.h"
#implementation FailCertificateDelegate
#synthesize dataDownloaded,downloaded;
-(id)init{
self = [super init];
if (self){
dataDownloaded=nil;
downloaded=[[NSCondition alloc] init];
}
return self;
}
- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace: (NSURLProtectionSpace *)protectionSpace {
NSLog(#"canAuthenticateAgainstProtectionSpace:");
return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge: (NSURLAuthenticationChallenge *)challenge {
NSLog(#"didReceiveAuthenticationChallenge:");
[challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust] forAuthenticationChallenge:challenge];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[downloaded signal];
[downloaded unlock];
self.hasFinnishLoading = YES;
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[dataDownloaded appendData:data];
[downloaded lock];
}
-(NSData *)getData{
if (!self.hasFinnishLoading){
[downloaded lock];
[downloaded wait];
[downloaded unlock];
}
return dataDownloaded;
}
#end
And for use it
FailCertificateDelegate *fcd=[[FailCertificateDelegate alloc] init];
NSURLConnection *c=[[NSURLConnection alloc] initWithRequest:request delegate:fcd startImmediately:NO];
[c setDelegateQueue:[[NSOperationQueue alloc] init]];
[c start];
NSData *d=[fcd getData];
Now you will have all benefits of have an async use of nsurlconnection and benefits of a simple sync connection, the thread will be blocked until you download all data on the delegate, but you could improve it adding some error control on FailCertificateDelegate class
EDIT: fix for big data. based on Nikolay DS comment. Thanks a lot

Answer 2

I had a similar issue. In my case i had an a-synchronous connection working with ssl as required using the two delegate methods that allowed me to accept any certificate:
- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
[challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust] forAuthenticationChallenge:challenge];
}
But i was stuck on doing the same in a synchronous manner. I searched the web until i found your post and unfortunately another stackoverflow post where it is hinted that you cannot perform synch calls on NSURLConnection and work with ssl (because of the lack of a delegate to handle the ssl authentication process).
What i ended up doing is getting ASIHTTPRequest and using that. It was painless to do and took me about an hour to set up and its working perfectly. here is how i use it.
+ (NSString *) getSynchronously:(NSDictionary *)parameters {
NSURL *url = [NSURL URLWithString:#"https://localhost:8443/MyApp/";
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];
NSString *parameterJSONString = [parameters JSONRepresentation];
[request appendPostString:parameterJSONString];
[request addRequestHeader:#"User-Agent" value:#"MyAgent"];
request.timeOutSeconds = CONNECTION_TIME_OUT_INTERVAL;
[request setValidatesSecureCertificate:NO];
[request startSynchronous];
NSString *responseString = [request responseString];
if (request.error) {
NSLog(#"Server connection failed: %#", [request.error localizedDescription]);
} else {
NSLog(#"Server response: %#", responseString);
}
return responseString;
}
The important part of course is the
[request setValidatesSecureCertificate:NO];
Another alternative for you is to handle the download in another thread with an a-synch connection using the two methods above and block the thread from which you want the synch connection until the request is complete

Answer 3

Im close to finding the solution for this with the code below. This works but often crashes
probably because I am doing something wrong in the way I code this and I don't have a strong understanding of the methods used. But if anyone has any suggestions on how to improve this
than please post.
Just after the line:
NSError* myError;
and just before the line:
NSData* myDataResult = [NSURLConnection sendSynchronousRequest:myURLRequest
returningResponse:&myURLResponse error:&myError];
add:
int failureCount = 0;
NSURLProtectionSpace *protectionSpace = [[NSURLProtectionSpace alloc]
initWithHost:#"mydomain.com" port:443 protocol:#"https" realm:nil
authenticationMethod:NSURLAuthenticationMethodServerTrust];
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:myURL MIMEType:#"text/html"
expectedContentLength:-1 textEncodingName:nil];
NSURLAuthenticationChallenge *challange = [[NSURLAuthenticationChallenge alloc]
initWithProtectionSpace:protectionSpace proposedCredential:[NSURLCredential
credentialForTrust:protectionSpace.serverTrust] previousFailureCount:failureCount
failureResponse:response error:myError sender:nil];