failed to connect to server is wrongly treated as handshake error

line 611 onwards socketio.m

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{
    NSLog(@"ERROR: handshake failed ... %@", [error localizedDescription]);

    _isConnected = NO;
    _isConnecting = NO;

    if ([_delegate respondsToSelector:@selector(socketIO:onError:)]) {
        NSMutableDictionary *errorInfo = [NSDictionary dictionaryWithObject:error forKey:NSLocalizedDescriptionKey];

        NSError *err = [NSError errorWithDomain:SocketIOError
                                           code:SocketIOHandshakeFailed
                                       userInfo:errorInfo];

        [_delegate socketIO:self onError:err];
    }
    // TODO: deprecated - to be removed
    else if ([_delegate respondsToSelector:@selector(socketIOHandshakeFailed:)]) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
        [_delegate socketIOHandshakeFailed:self];
#pragma clang diagnostic pop
    }
}

Even if the server was not reachable, it is being handled as handshake error, i suggest fixing it by adding a new error type, namely SocketIOServerCouldNotBeReached

//socketio.h
typedef enum {
    SocketIOServerRespondedWithInvalidConnectionData = -1,
    SocketIOServerRespondedWithDisconnect = -2,
    SocketIOHeartbeatTimeout = -3,
    SocketIOWebSocketClosed = -4,
    SocketIOTransportsNotSupported = -5,
    SocketIOHandshakeFailed = -6,
    SocketIODataCouldNotBeSend = -7,
    SocketIOServerCouldNotBeReached = -8,
} SocketIOErrorCodes;

and perhaps something along this line

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{
    NSLog(@"ERROR: handshake failed ... %@, %d", [error localizedDescription], [error code]);

    _isConnected = NO;
    _isConnecting = NO;

    if ([_delegate respondsToSelector:@selector(socketIO:onError:)]) {
        NSMutableDictionary *errorInfo = [NSDictionary dictionaryWithObject:error forKey:NSLocalizedDescriptionKey];
        NSError *err = nil;
        if ( 403 == error.code ) { // forbidden, according to the code in socket.io https://github.com/LearnBoost/socket.io/blob/0.9.14/lib/manager.js#L812
            err = [NSError errorWithDomain:SocketIOError
                                           code:SocketIOHandshakeFailed
                                       userInfo:errorInfo];
        } else if ( -1002 == error.code ) { // failed to reach server
            err = [NSError errorWithDomain:SocketIOError
                                      code:SocketIOServerCouldNotBeReached
                                  userInfo:errorInfo];
        }
        [_delegate socketIO:self onError:err];
    }
    // TODO: deprecated - to be removed
    else if ([_delegate respondsToSelector:@selector(socketIOHandshakeFailed:)] && 403 == error.code) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
        [_delegate socketIOHandshakeFailed:self];
#pragma clang diagnostic pop
    }
}

but of course written properly with maybe a mapping of error with the error code or something

seems like under the connection errors, apple has a lot of different error codes...

kCFURLErrorUnknown   = -998,
   kCFURLErrorCancelled = -999,
   kCFURLErrorBadURL    = -1000,
   kCFURLErrorTimedOut  = -1001,
   kCFURLErrorUnsupportedURL = -1002,
   kCFURLErrorCannotFindHost = -1003,
   kCFURLErrorCannotConnectToHost    = -1004,
   kCFURLErrorNetworkConnectionLost  = -1005,
   kCFURLErrorDNSLookupFailed        = -1006,
   kCFURLErrorHTTPTooManyRedirects   = -1007,
   kCFURLErrorResourceUnavailable    = -1008,
   kCFURLErrorNotConnectedToInternet = -1009,
   kCFURLErrorRedirectToNonExistentLocation = -1010,
   kCFURLErrorBadServerResponse             = -1011,
   kCFURLErrorUserCancelledAuthentication   = -1012,
   kCFURLErrorUserAuthenticationRequired    = -1013,
   kCFURLErrorZeroByteResource        = -1014,
   kCFURLErrorCannotDecodeRawData     = -1015,
   kCFURLErrorCannotDecodeContentData = -1016,
   kCFURLErrorCannotParseResponse     = -1017,
   kCFURLErrorInternationalRoamingOff = -1018,
   kCFURLErrorCallIsActive               = -1019,
   kCFURLErrorDataNotAllowed             = -1020,
   kCFURLErrorRequestBodyStreamExhausted = -1021,
   kCFURLErrorFileDoesNotExist           = -1100,
   kCFURLErrorFileIsDirectory            = -1101,
   kCFURLErrorNoPermissionsToReadFile    = -1102,
   kCFURLErrorDataLengthExceedsMaximum   = -1103,

the easiest thing would be to add the error.code to the errorInfo then you can handle the "handshake error" differently depending on the errorcode in your application.

well i suppose that can be done too, but that wouldnt be a very accurate representation of the true error wouldnt it? And this is a very general error, that is triggered by NSURLConnection. Of course, arguable since the only thing NSURLConnection is doing currently is for handshake?

I actually forked and implemented something similar to what I suggested and it seems to work, so what is your call for this? Since i think this really does cause certain problems in the long run, like for my case, if handshake failed I unauthenticate the app and if it cannot be reached it will just run offline mode

Edit: I meant if this is not fixed it can e a problem for some people in the long run