CocoaDev

I thought it would be interesting to write a CGI application in Objective C. However, I was unable to find an Objective C class for handling CGI parameters so I wrote one myself.

You just create a Foundation tool and then work your way from the main function using the class. For example, the following code will print out the name/value pairs passed to the CGI program:

#import <Foundation/Foundation.h> #import “ObjectiveCGI.h”

int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

// Create the CGI object
ObjectiveCGI *cgi = [[ObjectiveCGI alloc] init];

NSDictionary *params = [cgi getParams];
NSEnumerator *enumerator = [params keyEnumerator];
id key;

printf("Content-type: text/plain\n\n");

// Print out each key value pair as plain text
while ((key = [enumerator nextObject])) 
{
    printf("%s=%s",[key cString], 
                   params objectForKey: key] cString]);  
}
    
// Release the CGI object
[cgi release];

[pool release];
return 0; }

I’ve written some CGI programs, such as Vox Machina CGI (http://voxmachina.sytes.net) and [[VirtualSafari (http://virtualsafari.sytes.net) using this class. And here’s the code to the CGI class itself.

#import “ObjectiveCGI.h”

@implementation ObjectiveCGI

• (id) init { // dictionary for query key value pairs params = [[NSMutableDictionary alloc] initWithCapacity: 255];

  NSProcessInfo *processInfo = [NSProcessInfo processInfo]; env = [processInfo environment];

  if (env objectForKey: @”REQUEST_METHOD”] isEqualToString: @”GET”]) [self _parseGetQuery: [env objectForKey: @”QUERY_STRING”; else if (env objectForKey: @”REQUEST_METHOD”] isEqualToString: @”POST”]) [self _parsePostQuery]; else { [[NSLog(@”Missing REQUEST_METHOD”); return NULL; }

  if (self = [super init]) return self; }

• (void)dealloc { [params release]; [super dealloc]; }

• (NSString *)param: (NSString *)key { return [params objectForKey: key]; }

• (NSDictionary *) getParams { return params; }

• (NSDictionary *) env { return env; }

• (void) _parseGetQuery: (NSString *)queryStr { int i;

  if ([queryStr length] == 0) return;

  NSArray *pairs = [queryStr componentsSeparatedByString: @”&”];

  for (i = 0; i < [pairs count]; i++) { NSArray *elem = pairs objectAtIndex: i] componentsSeparatedByString: @”=”]; [params setObject: [[elem objectAtIndex: 1] stringByReplacingPercentEscapesUsingEncoding: NSUTF8StringEncoding] forKey: [elem objectAtIndex: 0; } }

• (void) _parsePostQuery { int i; int len = env objectForKey: @”CONTENT_LENGTH”] intValue]; if (len == 0) return;

  // read stdin for query string [[NSData *input = [[NSFileHandle fileHandleWithStandardInput] readDataOfLength: len]; NSString *queryStr = [[NSString alloc] initWithData: input encoding: 1]; NSArray *pairs = [queryStr componentsSeparatedByString: @”&”];

  for (i = 0; i < [pairs count]; i++) { NSArray *elem = pairs objectAtIndex: i] componentsSeparatedByString: @”=”]; [params setObject: [[elem objectAtIndex: 1] stringByReplacingPercentEscapesUsingEncoding: NSUTF8StringEncoding] forKey: [elem objectAtIndex: 0; } }

@end