ASIHTTPRequest problem with parameters using 3G conneciton (Fine with Wifi) - iphone

Question

I have one user of my iPhone application who is complaining it does not work when using his mobile data connection (but works fine via Wifi). My application make a request to a third party REST API and I use the ASIHTTPRequest library for this.
One parameter of my HTTP request is a username (which is an email address), so I encode the username using the following code:
-(NSString *) encodeString:(NSString *) string
{
NSString * returnString = (NSString *)CFURLCreateStringByAddingPercentEscapes(
NULL,
(CFStringRef) string,
NULL,
(CFStringRef)#"!*'();:#&=+$,/?%#[]",
kCFStringEncodingUTF8 );
return [returnString autorelease];
}
This then gets built into a URL as follows:
// Setup the url we need to make the request to the sharkscope API
NSString * urlString = [NSString stringWithFormat: #"%SERVICEADDRESSHERE?Username=%#&Password=%#",
encodedUserName, m_md5Key];
NSURL * url = [NSURL URLWithString:urlString];
request = [[ASIHTTPRequest requestWithURL:url] retain];
What get's sent out of my application is a request with the following Username:
Username=Fred.Bloggs%40wanadoo.fr
For this one user, what is received at the server when using his mobile data connection is:
Username=Fred.Bloogs%2540wanadoo.fr
So clearly the % character is being encoded somewhere between me making the call to requestWithURL and it arriving at the server. I can't understand the reason because I have hundreds of other users who can run the requests fine via their data connection.
Do I even need to encode the values passed into requestWithURL?
Does anyone have any idea at what stage the % character is being re-encoded. I'm guessing it must be in ASIHTTP library, but can't work out what circumstances would trigger it in this case.

Answer 1

The corruption is probably happening because of a proxy or transparent proxy on the 3G connection, put in place by the carrier.
Possibly workounds:
Use POST instead of GET
Use https instead of http
Use http on a non-standard port
To prove this theory, you could try asking him to enter the same / similar request in Safari on iOS when he's using the 3g connection.