/*
 Copyright (c) 2012-2015, Pierre-Olivier Latour
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.
 * The name of Pierre-Olivier Latour may not be used to endorse
 or promote products derived from this software without specific
 prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL PIERRE-OLIVIER LATOUR BE LIABLE FOR ANY
 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if !__has_feature(objc_arc)
#error GCDWebServer requires ARC
#endif

#import <TargetConditionals.h>
#import <netdb.h>
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
#import <libkern/OSAtomic.h>
#endif

#import "GCDWebServerPrivate.h"

#define kHeadersReadCapacity (1 * 1024)
#define kBodyReadCapacity (256 * 1024)

typedef void (^ReadDataCompletionBlock)(BOOL success);
typedef void (^ReadHeadersCompletionBlock)(NSData* extraData);
typedef void (^ReadBodyCompletionBlock)(BOOL success);

typedef void (^WriteDataCompletionBlock)(BOOL success);
typedef void (^WriteHeadersCompletionBlock)(BOOL success);
typedef void (^WriteBodyCompletionBlock)(BOOL success);

static NSData* _CRLFData = nil;
static NSData* _CRLFCRLFData = nil;
static NSData* _continueData = nil;
static NSData* _lastChunkData = nil;
static NSString* _digestAuthenticationNonce = nil;
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
static int32_t _connectionCounter = 0;
#endif

@interface GCDWebServerConnection () {
@private
  GCDWebServer* _server;
  NSData* _localAddress;
  NSData* _remoteAddress;
  CFSocketNativeHandle _socket;
  NSUInteger _bytesRead;
  NSUInteger _bytesWritten;
  BOOL _virtualHEAD;
  
  CFHTTPMessageRef _requestMessage;
  GCDWebServerRequest* _request;
  GCDWebServerHandler* _handler;
  CFHTTPMessageRef _responseMessage;
  GCDWebServerResponse* _response;
  NSInteger _statusCode;
  
  BOOL _opened;
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
  NSUInteger _connectionIndex;
  NSString* _requestPath;
  int _requestFD;
  NSString* _responsePath;
  int _responseFD;
#endif
}
@end

@implementation GCDWebServerConnection (Read)

- (void)_readData:(NSMutableData*)data withLength:(NSUInteger)length completionBlock:(ReadDataCompletionBlock)block {
  dispatch_read(_socket, length, kGCDWebServerGCDQueue, ^(dispatch_data_t buffer, int error) {
    
    @autoreleasepool {
      if (error == 0) {
        size_t size = dispatch_data_get_size(buffer);
        if (size > 0) {
          NSUInteger originalLength = data.length;
          dispatch_data_apply(buffer, ^bool(dispatch_data_t region, size_t chunkOffset, const void* chunkBytes, size_t chunkSize) {
            [data appendBytes:chunkBytes length:chunkSize];
            return true;
          });
          [self didReadBytes:((char*)data.bytes + originalLength) length:(data.length - originalLength)];
          block(YES);
        } else {
          if (_bytesRead > 0) {
            GWS_LOG_ERROR(@"No more data available on socket %i", _socket);
          } else {
            GWS_LOG_WARNING(@"No data received from socket %i", _socket);
          }
          block(NO);
        }
      } else {
        GWS_LOG_ERROR(@"Error while reading from socket %i: %s (%i)", _socket, strerror(error), error);
        block(NO);
      }
    }
    
  });
}

- (void)_readHeaders:(NSMutableData*)headersData withCompletionBlock:(ReadHeadersCompletionBlock)block {
  GWS_DCHECK(_requestMessage);
  [self _readData:headersData withLength:NSUIntegerMax completionBlock:^(BOOL success) {
    
    if (success) {
      NSRange range = [headersData rangeOfData:_CRLFCRLFData options:0 range:NSMakeRange(0, headersData.length)];
      if (range.location == NSNotFound) {
        [self _readHeaders:headersData withCompletionBlock:block];
      } else {
        NSUInteger length = range.location + range.length;
        if (CFHTTPMessageAppendBytes(_requestMessage, headersData.bytes, length)) {
          if (CFHTTPMessageIsHeaderComplete(_requestMessage)) {
            block([headersData subdataWithRange:NSMakeRange(length, headersData.length - length)]);
          } else {
            GWS_LOG_ERROR(@"Failed parsing request headers from socket %i", _socket);
            block(nil);
          }
        } else {
          GWS_LOG_ERROR(@"Failed appending request headers data from socket %i", _socket);
          block(nil);
        }
      }
    } else {
      block(nil);
    }
    
  }];
}

- (void)_readBodyWithRemainingLength:(NSUInteger)length completionBlock:(ReadBodyCompletionBlock)block {
  GWS_DCHECK([_request hasBody] && ![_request usesChunkedTransferEncoding]);
  NSMutableData* bodyData = [[NSMutableData alloc] initWithCapacity:kBodyReadCapacity];
  [self _readData:bodyData withLength:length completionBlock:^(BOOL success) {
    
    if (success) {
      if (bodyData.length <= length) {
        NSError* error = nil;
        if ([_request performWriteData:bodyData error:&error]) {
          NSUInteger remainingLength = length - bodyData.length;
          if (remainingLength) {
            [self _readBodyWithRemainingLength:remainingLength completionBlock:block];
          } else {
            block(YES);
          }
        } else {
          GWS_LOG_ERROR(@"Failed writing request body on socket %i: %@", _socket, error);
          block(NO);
        }
      } else {
        GWS_LOG_ERROR(@"Unexpected extra content reading request body on socket %i", _socket);
        block(NO);
        GWS_DNOT_REACHED();
      }
    } else {
      block(NO);
    }
    
  }];
}

static inline NSUInteger _ScanHexNumber(const void* bytes, NSUInteger size) {
  char buffer[size + 1];
  bcopy(bytes, buffer, size);
  buffer[size] = 0;
  char* end = NULL;
  long result = strtol(buffer, &end, 16);
  return ((end != NULL) && (*end == 0) && (result >= 0) ? result : NSNotFound);
}

- (void)_readNextBodyChunk:(NSMutableData*)chunkData completionBlock:(ReadBodyCompletionBlock)block {
  GWS_DCHECK([_request hasBody] && [_request usesChunkedTransferEncoding]);
  
  while (1) {
    NSRange range = [chunkData rangeOfData:_CRLFData options:0 range:NSMakeRange(0, chunkData.length)];
    if (range.location == NSNotFound) {
      break;
    }
    NSRange extensionRange = [chunkData rangeOfData:[NSData dataWithBytes:";" length:1] options:0 range:NSMakeRange(0, range.location)];  // Ignore chunk extensions
    NSUInteger length = _ScanHexNumber((char*)chunkData.bytes, extensionRange.location != NSNotFound ? extensionRange.location : range.location);
    if (length != NSNotFound) {
      if (length) {
        if (chunkData.length < range.location + range.length + length + 2) {
          break;
        }
        const char* ptr = (char*)chunkData.bytes + range.location + range.length + length;
        if ((*ptr == '\r') && (*(ptr + 1) == '\n')) {
          NSError* error = nil;
          if ([_request performWriteData:[chunkData subdataWithRange:NSMakeRange(range.location + range.length, length)] error:&error]) {
            [chunkData replaceBytesInRange:NSMakeRange(0, range.location + range.length + length + 2) withBytes:NULL length:0];
          } else {
            GWS_LOG_ERROR(@"Failed writing request body on socket %i: %@", _socket, error);
            block(NO);
            return;
          }
        } else {
          GWS_LOG_ERROR(@"Missing terminating CRLF sequence for chunk reading request body on socket %i", _socket);
          block(NO);
          return;
        }
      } else {
        NSRange trailerRange = [chunkData rangeOfData:_CRLFCRLFData options:0 range:NSMakeRange(range.location, chunkData.length - range.location)];  // Ignore trailers
        if (trailerRange.location != NSNotFound) {
          block(YES);
          return;
        }
      }
    } else {
      GWS_LOG_ERROR(@"Invalid chunk length reading request body on socket %i", _socket);
      block(NO);
      return;
    }
  }
  
  [self _readData:chunkData withLength:NSUIntegerMax completionBlock:^(BOOL success) {
    
    if (success) {
      [self _readNextBodyChunk:chunkData completionBlock:block];
    } else {
      block(NO);
    }
    
  }];
}

@end

@implementation GCDWebServerConnection (Write)

- (void)_writeData:(NSData*)data withCompletionBlock:(WriteDataCompletionBlock)block {
  dispatch_data_t buffer = dispatch_data_create(data.bytes, data.length, kGCDWebServerGCDQueue, ^{
    [data self];  // Keeps ARC from releasing data too early
  });
  dispatch_write(_socket, buffer, kGCDWebServerGCDQueue, ^(dispatch_data_t remainingData, int error) {
    
    @autoreleasepool {
      if (error == 0) {
        GWS_DCHECK(remainingData == NULL);
        [self didWriteBytes:data.bytes length:data.length];
        block(YES);
      } else {
        GWS_LOG_ERROR(@"Error while writing to socket %i: %s (%i)", _socket, strerror(error), error);
        block(NO);
      }
    }
    
  });
#if !OS_OBJECT_USE_OBJC_RETAIN_RELEASE
  dispatch_release(buffer);
#endif
}

- (void)_writeHeadersWithCompletionBlock:(WriteHeadersCompletionBlock)block {
  GWS_DCHECK(_responseMessage);
  CFDataRef data = CFHTTPMessageCopySerializedMessage(_responseMessage);
  [self _writeData:(__bridge NSData*)data withCompletionBlock:block];
  CFRelease(data);
}

- (void)_writeBodyWithCompletionBlock:(WriteBodyCompletionBlock)block {
  GWS_DCHECK([_response hasBody]);
  [_response performReadDataWithCompletion:^(NSData* data, NSError* error) {
    
    if (data) {
      if (data.length) {
        if (_response.usesChunkedTransferEncoding) {
          const char* hexString = [[NSString stringWithFormat:@"%lx", (unsigned long)data.length] UTF8String];
          size_t hexLength = strlen(hexString);
          NSData* chunk = [NSMutableData dataWithLength:(hexLength + 2 + data.length + 2)];
          if (chunk == nil) {
            GWS_LOG_ERROR(@"Failed allocating memory for response body chunk for socket %i: %@", _socket, error);
            block(NO);
            return;
          }
          char* ptr = (char*)[(NSMutableData*)chunk mutableBytes];
          bcopy(hexString, ptr, hexLength);
          ptr += hexLength;
          *ptr++ = '\r';
          *ptr++ = '\n';
          bcopy(data.bytes, ptr, data.length);
          ptr += data.length;
          *ptr++ = '\r';
          *ptr = '\n';
          data = chunk;
        }
        [self _writeData:data withCompletionBlock:^(BOOL success) {
          
          if (success) {
            [self _writeBodyWithCompletionBlock:block];
          } else {
            block(NO);
          }
          
        }];
      } else {
        if (_response.usesChunkedTransferEncoding) {
          [self _writeData:_lastChunkData withCompletionBlock:^(BOOL success) {
            
            block(success);
            
          }];
        } else {
          block(YES);
        }
      }
    } else {
      GWS_LOG_ERROR(@"Failed reading response body for socket %i: %@", _socket, error);
      block(NO);
    }
    
  }];
}

@end

@implementation GCDWebServerConnection

@synthesize server=_server, localAddressData=_localAddress, remoteAddressData=_remoteAddress, totalBytesRead=_bytesRead, totalBytesWritten=_bytesWritten;

+ (void)initialize {
  if (_CRLFData == nil) {
    _CRLFData = [[NSData alloc] initWithBytes:"\r\n" length:2];
    GWS_DCHECK(_CRLFData);
  }
  if (_CRLFCRLFData == nil) {
    _CRLFCRLFData = [[NSData alloc] initWithBytes:"\r\n\r\n" length:4];
    GWS_DCHECK(_CRLFCRLFData);
  }
  if (_continueData == nil) {
    CFHTTPMessageRef message = CFHTTPMessageCreateResponse(kCFAllocatorDefault, 100, NULL, kCFHTTPVersion1_1);
    _continueData = CFBridgingRelease(CFHTTPMessageCopySerializedMessage(message));
    CFRelease(message);
    GWS_DCHECK(_continueData);
  }
  if (_lastChunkData == nil) {
    _lastChunkData = [[NSData alloc] initWithBytes:"0\r\n\r\n" length:5];
  }
  if (_digestAuthenticationNonce == nil) {
    CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
    _digestAuthenticationNonce = GCDWebServerComputeMD5Digest(@"%@", CFBridgingRelease(CFUUIDCreateString(kCFAllocatorDefault, uuid)));
    CFRelease(uuid);
  }
}

- (BOOL)isUsingIPv6 {
  const struct sockaddr* localSockAddr = _localAddress.bytes;
  return (localSockAddr->sa_family == AF_INET6);
}

- (void)_initializeResponseHeadersWithStatusCode:(NSInteger)statusCode {
  _statusCode = statusCode;
  _responseMessage = CFHTTPMessageCreateResponse(kCFAllocatorDefault, statusCode, NULL, kCFHTTPVersion1_1);
  CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Connection"), CFSTR("Close"));
  CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Server"), (__bridge CFStringRef)_server.serverName);
  CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Date"), (__bridge CFStringRef)GCDWebServerFormatRFC822([NSDate date]));
}

- (void)_startProcessingRequest {
  GWS_DCHECK(_responseMessage == NULL);
  
  GCDWebServerResponse* preflightResponse = [self preflightRequest:_request];
  if (preflightResponse) {
    [self _finishProcessingRequest:preflightResponse];
  } else {
    [self processRequest:_request completion:^(GCDWebServerResponse* processResponse) {
      [self _finishProcessingRequest:processResponse];
    }];
  }
}

// http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
- (void)_finishProcessingRequest:(GCDWebServerResponse*)response {
  GWS_DCHECK(_responseMessage == NULL);
  BOOL hasBody = NO;
  
  if (response) {
    response = [self overrideResponse:response forRequest:_request];
  }
  if (response) {
    if ([response hasBody]) {
      [response prepareForReading];
      hasBody = !_virtualHEAD;
    }
    NSError* error = nil;
    if (hasBody && ![response performOpen:&error]) {
      GWS_LOG_ERROR(@"Failed opening response body for socket %i: %@", _socket, error);
    } else {
      _response = response;
    }
  }
  
  if (_response) {
    [self _initializeResponseHeadersWithStatusCode:_response.statusCode];
    if (_response.lastModifiedDate) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Last-Modified"), (__bridge CFStringRef)GCDWebServerFormatRFC822(_response.lastModifiedDate));
    }
    if (_response.eTag) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("ETag"), (__bridge CFStringRef)_response.eTag);
    }
    if ((_response.statusCode >= 200) && (_response.statusCode < 300)) {
      if (_response.cacheControlMaxAge > 0) {
        CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Cache-Control"), (__bridge CFStringRef)[NSString stringWithFormat:@"max-age=%i, public", (int)_response.cacheControlMaxAge]);
      } else {
        CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Cache-Control"), CFSTR("no-cache"));
      }
    }
    if (_response.contentType != nil) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Content-Type"), (__bridge CFStringRef)GCDWebServerNormalizeHeaderValue(_response.contentType));
    }
    if (_response.contentLength != NSUIntegerMax) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Content-Length"), (__bridge CFStringRef)[NSString stringWithFormat:@"%lu", (unsigned long)_response.contentLength]);
    }
    if (_response.usesChunkedTransferEncoding) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, CFSTR("Transfer-Encoding"), CFSTR("chunked"));
    }
    [_response.additionalHeaders enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL* stop) {
      CFHTTPMessageSetHeaderFieldValue(_responseMessage, (__bridge CFStringRef)key, (__bridge CFStringRef)obj);
    }];
    [self _writeHeadersWithCompletionBlock:^(BOOL success) {
      
      if (success) {
        if (hasBody) {
          [self _writeBodyWithCompletionBlock:^(BOOL successInner) {
            
            [_response performClose];  // TODO: There's nothing we can do on failure as headers have already been sent
            
          }];
        }
      } else if (hasBody) {
        [_response performClose];
      }
      
    }];
  } else {
    [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
  }
  
}

- (void)_readBodyWithLength:(NSUInteger)length initialData:(NSData*)initialData {
  NSError* error = nil;
  if (![_request performOpen:&error]) {
    GWS_LOG_ERROR(@"Failed opening request body for socket %i: %@", _socket, error);
    [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
    return;
  }
  
  if (initialData.length) {
    if (![_request performWriteData:initialData error:&error]) {
      GWS_LOG_ERROR(@"Failed writing request body on socket %i: %@", _socket, error);
      if (![_request performClose:&error]) {
        GWS_LOG_ERROR(@"Failed closing request body for socket %i: %@", _socket, error);
      }
      [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
      return;
    }
    length -= initialData.length;
  }
  
  if (length) {
    [self _readBodyWithRemainingLength:length completionBlock:^(BOOL success) {
      
      NSError* localError = nil;
      if ([_request performClose:&localError]) {
        [self _startProcessingRequest];
      } else {
        GWS_LOG_ERROR(@"Failed closing request body for socket %i: %@", _socket, error);
        [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
      }
      
    }];
  } else {
    if ([_request performClose:&error]) {
      [self _startProcessingRequest];
    } else {
      GWS_LOG_ERROR(@"Failed closing request body for socket %i: %@", _socket, error);
      [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
    }
  }
}

- (void)_readChunkedBodyWithInitialData:(NSData*)initialData {
  NSError* error = nil;
  if (![_request performOpen:&error]) {
    GWS_LOG_ERROR(@"Failed opening request body for socket %i: %@", _socket, error);
    [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
    return;
  }
  
  NSMutableData* chunkData = [[NSMutableData alloc] initWithData:initialData];
  [self _readNextBodyChunk:chunkData completionBlock:^(BOOL success) {
  
    NSError* localError = nil;
    if ([_request performClose:&localError]) {
      [self _startProcessingRequest];
    } else {
      GWS_LOG_ERROR(@"Failed closing request body for socket %i: %@", _socket, error);
      [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
    }
    
  }];
}

- (void)_readRequestHeaders {
  _requestMessage = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, true);
  NSMutableData* headersData = [[NSMutableData alloc] initWithCapacity:kHeadersReadCapacity];
  [self _readHeaders:headersData withCompletionBlock:^(NSData* extraData) {
    
    if (extraData) {
      NSString* requestMethod = CFBridgingRelease(CFHTTPMessageCopyRequestMethod(_requestMessage));  // Method verbs are case-sensitive and uppercase
      if (_server.shouldAutomaticallyMapHEADToGET && [requestMethod isEqualToString:@"HEAD"]) {
        requestMethod = @"GET";
        _virtualHEAD = YES;
      }
      NSDictionary* requestHeaders = CFBridgingRelease(CFHTTPMessageCopyAllHeaderFields(_requestMessage));  // Header names are case-insensitive but CFHTTPMessageCopyAllHeaderFields() will standardize the common ones
      NSURL* requestURL = CFBridgingRelease(CFHTTPMessageCopyRequestURL(_requestMessage));
      if (requestURL) {
        requestURL = [self rewriteRequestURL:requestURL withMethod:requestMethod headers:requestHeaders];
        GWS_DCHECK(requestURL);
      }
      NSString* requestPath = requestURL ? GCDWebServerUnescapeURLString(CFBridgingRelease(CFURLCopyPath((CFURLRef)requestURL))) : nil;  // Don't use -[NSURL path] which strips the ending slash
      NSString* queryString = requestURL ? CFBridgingRelease(CFURLCopyQueryString((CFURLRef)requestURL, NULL)) : nil;  // Don't use -[NSURL query] to make sure query is not unescaped;
      NSDictionary* requestQuery = queryString ? GCDWebServerParseURLEncodedForm(queryString) : @{};
      if (requestMethod && requestURL && requestHeaders && requestPath && requestQuery) {
        for (_handler in _server.handlers) {
          _request = _handler.matchBlock(requestMethod, requestURL, requestHeaders, requestPath, requestQuery);
          if (_request) {
            break;
          }
        }
        if (_request) {
          _request.localAddressData = self.localAddressData;
          _request.remoteAddressData = self.remoteAddressData;
          if ([_request hasBody]) {
            [_request prepareForWriting];
            if (_request.usesChunkedTransferEncoding || (extraData.length <= _request.contentLength)) {
              NSString* expectHeader = [requestHeaders objectForKey:@"Expect"];
              if (expectHeader) {
                if ([expectHeader caseInsensitiveCompare:@"100-continue"] == NSOrderedSame) {  // TODO: Actually validate request before continuing
                  [self _writeData:_continueData withCompletionBlock:^(BOOL success) {
                    
                    if (success) {
                      if (_request.usesChunkedTransferEncoding) {
                        [self _readChunkedBodyWithInitialData:extraData];
                      } else {
                        [self _readBodyWithLength:_request.contentLength initialData:extraData];
                      }
                    }
                    
                  }];
                } else {
                  GWS_LOG_ERROR(@"Unsupported 'Expect' / 'Content-Length' header combination on socket %i", _socket);
                  [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_ExpectationFailed];
                }
              } else {
                if (_request.usesChunkedTransferEncoding) {
                  [self _readChunkedBodyWithInitialData:extraData];
                } else {
                  [self _readBodyWithLength:_request.contentLength initialData:extraData];
                }
              }
            } else {
              GWS_LOG_ERROR(@"Unexpected 'Content-Length' header value on socket %i", _socket);
              [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_BadRequest];
            }
          } else {
            [self _startProcessingRequest];
          }
        } else {
          _request = [[GCDWebServerRequest alloc] initWithMethod:requestMethod url:requestURL headers:requestHeaders path:requestPath query:requestQuery];
          GWS_DCHECK(_request);
          [self abortRequest:_request withStatusCode:kGCDWebServerHTTPStatusCode_MethodNotAllowed];
        }
      } else {
        [self abortRequest:nil withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
        GWS_DNOT_REACHED();
      }
    } else {
      [self abortRequest:nil withStatusCode:kGCDWebServerHTTPStatusCode_InternalServerError];
    }
    
  }];
}

- (id)initWithServer:(GCDWebServer*)server localAddress:(NSData*)localAddress remoteAddress:(NSData*)remoteAddress socket:(CFSocketNativeHandle)socket {
  if ((self = [super init])) {
    _server = server;
    _localAddress = localAddress;
    _remoteAddress = remoteAddress;
    _socket = socket;
    GWS_LOG_DEBUG(@"Did open connection on socket %i", _socket);
    
    [_server willStartConnection:self];
    
    if (![self open]) {
      close(_socket);
      return nil;
    }
    _opened = YES;
    
    [self _readRequestHeaders];
  }
  return self;
}

- (NSString*)localAddressString {
  return GCDWebServerStringFromSockAddr(_localAddress.bytes, YES);
}

- (NSString*)remoteAddressString {
  return GCDWebServerStringFromSockAddr(_remoteAddress.bytes, YES);
}

- (void)dealloc {
  int result = close(_socket);
  if (result != 0) {
    GWS_LOG_ERROR(@"Failed closing socket %i for connection: %s (%i)", _socket, strerror(errno), errno);
  } else {
    GWS_LOG_DEBUG(@"Did close connection on socket %i", _socket);
  }
  
  if (_opened) {
    [self close];
  }
  
  [_server didEndConnection:self];
  
  if (_requestMessage) {
    CFRelease(_requestMessage);
  }
  
  if (_responseMessage) {
    CFRelease(_responseMessage);
  }
}

@end

@implementation GCDWebServerConnection (Subclassing)

- (BOOL)open {
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
  if (_server.recordingEnabled) {
    _connectionIndex = OSAtomicIncrement32(&_connectionCounter);
    
    _requestPath = [NSTemporaryDirectory() stringByAppendingPathComponent:[[NSProcessInfo processInfo] globallyUniqueString]];
    _requestFD = open([_requestPath fileSystemRepresentation], O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    GWS_DCHECK(_requestFD > 0);
    
    _responsePath = [NSTemporaryDirectory() stringByAppendingPathComponent:[[NSProcessInfo processInfo] globallyUniqueString]];
    _responseFD = open([_responsePath fileSystemRepresentation], O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    GWS_DCHECK(_responseFD > 0);
  }
#endif
  
  return YES;
}

- (void)didReadBytes:(const void*)bytes length:(NSUInteger)length {
  GWS_LOG_DEBUG(@"Connection received %lu bytes on socket %i", (unsigned long)length, _socket);
  _bytesRead += length;
  
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
  if ((_requestFD > 0) && (write(_requestFD, bytes, length) != (ssize_t)length)) {
    GWS_LOG_ERROR(@"Failed recording request data: %s (%i)", strerror(errno), errno);
    close(_requestFD);
    _requestFD = 0;
  }
#endif
}

- (void)didWriteBytes:(const void*)bytes length:(NSUInteger)length {
  GWS_LOG_DEBUG(@"Connection sent %lu bytes on socket %i", (unsigned long)length, _socket);
  _bytesWritten += length;
  
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
  if ((_responseFD > 0) && (write(_responseFD, bytes, length) != (ssize_t)length)) {
    GWS_LOG_ERROR(@"Failed recording response data: %s (%i)", strerror(errno), errno);
    close(_responseFD);
    _responseFD = 0;
  }
#endif
}

- (NSURL*)rewriteRequestURL:(NSURL*)url withMethod:(NSString*)method headers:(NSDictionary*)headers {
  return url;
}

// https://tools.ietf.org/html/rfc2617
- (GCDWebServerResponse*)preflightRequest:(GCDWebServerRequest*)request {
  GWS_LOG_DEBUG(@"Connection on socket %i preflighting request \"%@ %@\" with %lu bytes body", _socket, _virtualHEAD ? @"HEAD" : _request.method, _request.path, (unsigned long)_bytesRead);
  GCDWebServerResponse* response = nil;
  if (_server.authenticationBasicAccounts) {
    __block BOOL authenticated = NO;
    NSString* authorizationHeader = [request.headers objectForKey:@"Authorization"];
    if ([authorizationHeader hasPrefix:@"Basic "]) {
      NSString* basicAccount = [authorizationHeader substringFromIndex:6];
      [_server.authenticationBasicAccounts enumerateKeysAndObjectsUsingBlock:^(NSString* username, NSString* digest, BOOL* stop) {
        if ([basicAccount isEqualToString:digest]) {
          authenticated = YES;
          *stop = YES;
        }
      }];
    }
    if (!authenticated) {
      response = [GCDWebServerResponse responseWithStatusCode:kGCDWebServerHTTPStatusCode_Unauthorized];
      [response setValue:[NSString stringWithFormat:@"Basic realm=\"%@\"", _server.authenticationRealm] forAdditionalHeader:@"WWW-Authenticate"];
    }
  } else if (_server.authenticationDigestAccounts) {
    BOOL authenticated = NO;
    BOOL isStaled = NO;
    NSString* authorizationHeader = [request.headers objectForKey:@"Authorization"];
    if ([authorizationHeader hasPrefix:@"Digest "]) {
      NSString* realm = GCDWebServerExtractHeaderValueParameter(authorizationHeader, @"realm");
      if ([realm isEqualToString:_server.authenticationRealm]) {
        NSString* nonce = GCDWebServerExtractHeaderValueParameter(authorizationHeader, @"nonce");
        if ([nonce isEqualToString:_digestAuthenticationNonce]) {
          NSString* username = GCDWebServerExtractHeaderValueParameter(authorizationHeader, @"username");
          NSString* uri = GCDWebServerExtractHeaderValueParameter(authorizationHeader, @"uri");
          NSString* actualResponse = GCDWebServerExtractHeaderValueParameter(authorizationHeader, @"response");
          NSString* ha1 = [_server.authenticationDigestAccounts objectForKey:username];
          NSString* ha2 = GCDWebServerComputeMD5Digest(@"%@:%@", request.method, uri);  // We cannot use "request.path" as the query string is required
          NSString* expectedResponse = GCDWebServerComputeMD5Digest(@"%@:%@:%@", ha1, _digestAuthenticationNonce, ha2);
          if ([actualResponse isEqualToString:expectedResponse]) {
            authenticated = YES;
          }
        } else if (nonce.length) {
          isStaled = YES;
        }
      }
    }
    if (!authenticated) {
      response = [GCDWebServerResponse responseWithStatusCode:kGCDWebServerHTTPStatusCode_Unauthorized];
      [response setValue:[NSString stringWithFormat:@"Digest realm=\"%@\", nonce=\"%@\"%@", _server.authenticationRealm, _digestAuthenticationNonce, isStaled ? @", stale=TRUE" : @""] forAdditionalHeader:@"WWW-Authenticate"];  // TODO: Support Quality of Protection ("qop")
    }
  }
  return response;
}

- (void)processRequest:(GCDWebServerRequest*)request completion:(GCDWebServerCompletionBlock)completion {
  GWS_LOG_DEBUG(@"Connection on socket %i processing request \"%@ %@\" with %lu bytes body", _socket, _virtualHEAD ? @"HEAD" : _request.method, _request.path, (unsigned long)_bytesRead);
  @try {
    _handler.asyncProcessBlock(request, [completion copy]);
  }
  @catch (NSException* exception) {
    GWS_LOG_EXCEPTION(exception);
  }
}

// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.25
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26
static inline BOOL _CompareResources(NSString* responseETag, NSString* requestETag, NSDate* responseLastModified, NSDate* requestLastModified) {
  if (requestLastModified && responseLastModified) {
    if ([responseLastModified compare:requestLastModified] != NSOrderedDescending) {
      return YES;
    }
  }
  if (requestETag && responseETag) {  // Per the specs "If-None-Match" must be checked after "If-Modified-Since"
    if ([requestETag isEqualToString:@"*"]) {
      return YES;
    }
    if ([responseETag isEqualToString:requestETag]) {
      return YES;
    }
  }
  return NO;
}

- (GCDWebServerResponse*)overrideResponse:(GCDWebServerResponse*)response forRequest:(GCDWebServerRequest*)request {
  if ((response.statusCode >= 200) && (response.statusCode < 300) && _CompareResources(response.eTag, request.ifNoneMatch, response.lastModifiedDate, request.ifModifiedSince)) {
    NSInteger code = [request.method isEqualToString:@"HEAD"] || [request.method isEqualToString:@"GET"] ? kGCDWebServerHTTPStatusCode_NotModified : kGCDWebServerHTTPStatusCode_PreconditionFailed;
    GCDWebServerResponse* newResponse = [GCDWebServerResponse responseWithStatusCode:code];
    newResponse.cacheControlMaxAge = response.cacheControlMaxAge;
    newResponse.lastModifiedDate = response.lastModifiedDate;
    newResponse.eTag = response.eTag;
    GWS_DCHECK(newResponse);
    return newResponse;
  }
  return response;
}

- (void)abortRequest:(GCDWebServerRequest*)request withStatusCode:(NSInteger)statusCode {
  GWS_DCHECK(_responseMessage == NULL);
  GWS_DCHECK((statusCode >= 400) && (statusCode < 600));
  [self _initializeResponseHeadersWithStatusCode:statusCode];
  [self _writeHeadersWithCompletionBlock:^(BOOL success) {
    ;  // Nothing more to do
  }];
  GWS_LOG_DEBUG(@"Connection aborted with status code %i on socket %i", (int)statusCode, _socket);
}

- (void)close {
#ifdef __GCDWEBSERVER_ENABLE_TESTING__
  if (_requestPath) {
    BOOL success = NO;
    NSError* error = nil;
    if (_requestFD > 0) {
      close(_requestFD);
      NSString* name = [NSString stringWithFormat:@"%03lu-%@.request", (unsigned long)_connectionIndex, _virtualHEAD ? @"HEAD" : _request.method];
      success = [[NSFileManager defaultManager] moveItemAtPath:_requestPath toPath:[[[NSFileManager defaultManager] currentDirectoryPath] stringByAppendingPathComponent:name] error:&error];
    }
    if (!success) {
      GWS_LOG_ERROR(@"Failed saving recorded request: %@", error);
      GWS_DNOT_REACHED();
    }
    unlink([_requestPath fileSystemRepresentation]);
  }
  
  if (_responsePath) {
    BOOL success = NO;
    NSError* error = nil;
    if (_responseFD > 0) {
      close(_responseFD);
      NSString* name = [NSString stringWithFormat:@"%03lu-%i.response", (unsigned long)_connectionIndex, (int)_statusCode];
      success = [[NSFileManager defaultManager] moveItemAtPath:_responsePath toPath:[[[NSFileManager defaultManager] currentDirectoryPath] stringByAppendingPathComponent:name] error:&error];
    }
    if (!success) {
      GWS_LOG_ERROR(@"Failed saving recorded response: %@", error);
      GWS_DNOT_REACHED();
    }
    unlink([_responsePath fileSystemRepresentation]);
  }
#endif
  
  if (_request) {
    GWS_LOG_VERBOSE(@"[%@] %@ %i \"%@ %@\" (%lu | %lu)", self.localAddressString, self.remoteAddressString, (int)_statusCode, _virtualHEAD ? @"HEAD" : _request.method, _request.path, (unsigned long)_bytesRead, (unsigned long)_bytesWritten);
  } else {
    GWS_LOG_VERBOSE(@"[%@] %@ %i \"(invalid request)\" (%lu | %lu)", self.localAddressString, self.remoteAddressString, (int)_statusCode, (unsigned long)_bytesRead, (unsigned long)_bytesWritten);
  }
}

@end