SocketRocket研究三协议数据封装

socket是一种http的长连接请求，只是发送的数据格式要符合协议标准

/* From RFC:

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-------+-+-------------+-------------------------------+
 |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
 |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
 |N|V|V|V|       |S|             |   (if payload len==126/127)   |
 | |1|2|3|       |K|             |                               |
 +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
 |     Extended payload length continued, if payload len == 127  |
 + - - - - - - - - - - - - - - - +-------------------------------+
 |                               |Masking-key, if MASK set to 1  |
 +-------------------------------+-------------------------------+
 | Masking-key (continued)       |          Payload Data         |
 +-------------------------------- - - - - - - - - - - - - - - - +
 :                     Payload Data continued ...                :
 + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
 |                     Payload Data continued ...                |
 +---------------------------------------------------------------+
 */

1、发送数据
连接开启后会发送一次请求参数
将request里的内容封装成NSData

-(void)didConnect;
{
CFHTTPMessageRef request = CFHTTPMessageCreateRequest(NULL, CFSTR("GET"), (__bridge CFURLRef)_url, kCFHTTPVersion1_1);
    
    // Set host first so it defaults
    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Host"), (__bridge CFStringRef)(_url.port ? [NSString stringWithFormat:@"%@:%@", _url.host, _url.port] : _url.host));
        
    NSMutableData *keyBytes = [[NSMutableData alloc] initWithLength:16];
    SecRandomCopyBytes(kSecRandomDefault, keyBytes.length, keyBytes.mutableBytes);
    
    if ([keyBytes respondsToSelector:@selector(base64EncodedStringWithOptions:)]) {
        _secKey = [keyBytes base64EncodedStringWithOptions:0];
    } else {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
        _secKey = [keyBytes base64Encoding];
#pragma clang diagnostic pop
    }
    
    assert([_secKey length] == 24);

    // Apply cookies if any have been provided
    NSDictionary * cookies = [NSHTTPCookie requestHeaderFieldsWithCookies:[self requestCookies]];
    for (NSString * cookieKey in cookies) {
        NSString * cookieValue = [cookies objectForKey:cookieKey];
        if ([cookieKey length] && [cookieValue length]) {
            CFHTTPMessageSetHeaderFieldValue(request, (__bridge CFStringRef)cookieKey, (__bridge CFStringRef)cookieValue);
        }
    }
 
    // set header for http basic auth
    if (_url.user.length && _url.password.length) {
        NSData *userAndPassword = [[NSString stringWithFormat:@"%@:%@", _url.user, _url.password] dataUsingEncoding:NSUTF8StringEncoding];
        NSString *userAndPasswordBase64Encoded;
        if ([keyBytes respondsToSelector:@selector(base64EncodedStringWithOptions:)]) {
            userAndPasswordBase64Encoded = [userAndPassword base64EncodedStringWithOptions:0];
        } else {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
            userAndPasswordBase64Encoded = [userAndPassword base64Encoding];
#pragma clang diagnostic pop
        }
        _basicAuthorizationString = [NSString stringWithFormat:@"Basic %@", userAndPasswordBase64Encoded];
        CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Authorization"), (__bridge CFStringRef)_basicAuthorizationString);
    }

    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Upgrade"), CFSTR("websocket"));
    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Connection"), CFSTR("Upgrade"));
    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Key"), (__bridge CFStringRef)_secKey);
    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Version"), (__bridge CFStringRef)[NSString stringWithFormat:@"%ld", (long)_webSocketVersion]);
    
    CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Origin"), (__bridge CFStringRef)_url.SR_origin);
    
    if (_requestedProtocols) {
        CFHTTPMessageSetHeaderFieldValue(request, CFSTR("Sec-WebSocket-Protocol"), (__bridge CFStringRef)[_requestedProtocols componentsJoinedByString:@", "]);
    }

    [_urlRequest.allHTTPHeaderFields enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        CFHTTPMessageSetHeaderFieldValue(request, (__bridge CFStringRef)key, (__bridge CFStringRef)obj);
    }];
    
    NSData *message = CFBridgingRelease(CFHTTPMessageCopySerializedMessage(request));
    
    CFRelease(request);

    [self _writeData:message];
}
- (void)_writeData:(NSData *)data;
{    
    [self assertOnWorkQueue];

    if (_closeWhenFinishedWriting) {
            return;
    }
    [_outputBuffer appendData:data];
    [self _pumpWriting];
}

发送一般数据

- (void)send:(id)data;
{
    NSAssert(self.readyState != SR_CONNECTING, @"Invalid State: Cannot call send: until connection is open");
    // TODO: maybe not copy this for performance
    data = [data copy];
    dispatch_async(_workQueue, ^{
        if ([data isKindOfClass:[NSString class]]) {
            [self _sendFrameWithOpcode:SROpCodeTextFrame data:[(NSString *)data dataUsingEncoding:NSUTF8StringEncoding]];
        } else if ([data isKindOfClass:[NSData class]]) {
            [self _sendFrameWithOpcode:SROpCodeBinaryFrame data:data];
        } else if (data == nil) {
            [self _sendFrameWithOpcode:SROpCodeTextFrame data:data];
        } else {
            assert(NO);
        }
    });
}

将数据转换成标准协议格式的NSData

static const size_t SRFrameHeaderOverhead = 32;

- (void)_sendFrameWithOpcode:(SROpCode)opcode data:(id)data;
{
    [self assertOnWorkQueue];
    
    if (nil == data) {
        return;
    }
    
    NSAssert([data isKindOfClass:[NSData class]] || [data isKindOfClass:[NSString class]], @"NSString or NSData");
    
    size_t payloadLength = [data isKindOfClass:[NSString class]] ? [(NSString *)data lengthOfBytesUsingEncoding:NSUTF8StringEncoding] : [data length];
        
    NSMutableData *frame = [[NSMutableData alloc] initWithLength:payloadLength + SRFrameHeaderOverhead];
    if (!frame) {
        [self closeWithCode:SRStatusCodeMessageTooBig reason:@"Message too big"];
        return;
    }
    uint8_t *frame_buffer = (uint8_t *)[frame mutableBytes];
    
    // set fin
    frame_buffer[0] = SRFinMask | opcode;
    
    BOOL useMask = YES;
#ifdef NOMASK
    useMask = NO;
#endif
    
    if (useMask) {
    // set the mask and header
        frame_buffer[1] |= SRMaskMask;
    }
    
    size_t frame_buffer_size = 2;
    
    const uint8_t *unmasked_payload = NULL;
    if ([data isKindOfClass:[NSData class]]) {
        unmasked_payload = (uint8_t *)[data bytes];
    } else if ([data isKindOfClass:[NSString class]]) {
        unmasked_payload =  (const uint8_t *)[data UTF8String];
    } else {
        return;
    }
    
    if (payloadLength < 126) {
        frame_buffer[1] |= payloadLength;
    } else if (payloadLength <= UINT16_MAX) {
        frame_buffer[1] |= 126;
        *((uint16_t *)(frame_buffer + frame_buffer_size)) = EndianU16_BtoN((uint16_t)payloadLength);
        frame_buffer_size += sizeof(uint16_t);
    } else {
        frame_buffer[1] |= 127;
        *((uint64_t *)(frame_buffer + frame_buffer_size)) = EndianU64_BtoN((uint64_t)payloadLength);
        frame_buffer_size += sizeof(uint64_t);
    }
        
    if (!useMask) {
        for (size_t i = 0; i < payloadLength; i++) {
            frame_buffer[frame_buffer_size] = unmasked_payload[i];
            frame_buffer_size += 1;
        }
    } else {
        uint8_t *mask_key = frame_buffer + frame_buffer_size;
        SecRandomCopyBytes(kSecRandomDefault, sizeof(uint32_t), (uint8_t *)mask_key);
        frame_buffer_size += sizeof(uint32_t);
        
        // TODO: could probably optimize this with SIMD
        for (size_t i = 0; i < payloadLength; i++) {
            frame_buffer[frame_buffer_size] = unmasked_payload[i] ^ mask_key[i % sizeof(uint32_t)];
            frame_buffer_size += 1;
        }
    }

    assert(frame_buffer_size <= [frame length]);
    frame.length = frame_buffer_size;
    
    [self _writeData:frame];
}

数据封装

typedef enum  {
    SROpCodeTextFrame = 0x1,
    SROpCodeBinaryFrame = 0x2,
    // 3-7 reserved.
    SROpCodeConnectionClose = 0x8,
    SROpCodePing = 0x9,
    SROpCodePong = 0xA,
    // B-F reserved.
} SROpCode;
// 第一个字节设置fin
uint8_t *frame_buffer = (uint8_t *)[frame mutableBytes];
    
    // set fin
    frame_buffer[0] = SRFinMask | opcode;
// 设置mask
frame_buffer[1] |= SRMaskMask;
//设置payload
if (payloadLength < 126) {
        frame_buffer[1] |= payloadLength;
    } else if (payloadLength <= UINT16_MAX) {
        frame_buffer[1] |= 126;
        *((uint16_t *)(frame_buffer + frame_buffer_size)) = EndianU16_BtoN((uint16_t)payloadLength);
        frame_buffer_size += sizeof(uint16_t);
    } else {
        frame_buffer[1] |= 127;
        *((uint64_t *)(frame_buffer + frame_buffer_size)) = EndianU64_BtoN((uint64_t)payloadLength);
        frame_buffer_size += sizeof(uint64_t);
    }
// 设置mask_key
uint8_t *mask_key = frame_buffer + frame_buffer_size;
        SecRandomCopyBytes(kSecRandomDefault, sizeof(uint32_t), (uint8_t *)mask_key);
        frame_buffer_size += sizeof(uint32_t);
        
        // TODO: could probably optimize this with SIMD
        for (size_t i = 0; i < payloadLength; i++) {
            frame_buffer[frame_buffer_size] = unmasked_payload[i] ^ mask_key[i % sizeof(uint32_t)];
            frame_buffer_size += 1;
        }

读取数据

-(void)_readFrameContinue;
{
    assert((_currentFrameCount == 0 && _currentFrameOpcode == 0) || (_currentFrameCount > 0 && _currentFrameOpcode > 0));

    [self _addConsumerWithDataLength:2 callback:^(SRWebSocket *self, NSData *data) {
        __block frame_header header = {0};
        
        const uint8_t *headerBuffer = data.bytes;
        assert(data.length >= 2);
        
        if (headerBuffer[0] & SRRsvMask) {
            [self _closeWithProtocolError:@"Server used RSV bits"];
            return;
        }
        
        uint8_t receivedOpcode = (SROpCodeMask & headerBuffer[0]);
        
        BOOL isControlFrame = (receivedOpcode == SROpCodePing || receivedOpcode == SROpCodePong || receivedOpcode == SROpCodeConnectionClose);
        
        if (!isControlFrame && receivedOpcode != 0 && self->_currentFrameCount > 0) {
            [self _closeWithProtocolError:@"all data frames after the initial data frame must have opcode 0"];
            return;
        }
        
        if (receivedOpcode == 0 && self->_currentFrameCount == 0) {
            [self _closeWithProtocolError:@"cannot continue a message"];
            return;
        }
        
        header.opcode = receivedOpcode == 0 ? self->_currentFrameOpcode : receivedOpcode;
        
        header.fin = !!(SRFinMask & headerBuffer[0]);
        
        
        header.masked = !!(SRMaskMask & headerBuffer[1]);
        header.payload_length = SRPayloadLenMask & headerBuffer[1];
        
        headerBuffer = NULL;
        
        if (header.masked) {
            [self _closeWithProtocolError:@"Client must receive unmasked data"];
        }
        
        size_t extra_bytes_needed = header.masked ? sizeof(_currentReadMaskKey) : 0;
        
        if (header.payload_length == 126) {
            extra_bytes_needed += sizeof(uint16_t);
        } else if (header.payload_length == 127) {
            extra_bytes_needed += sizeof(uint64_t);
        }
        
        if (extra_bytes_needed == 0) {
            [self _handleFrameHeader:header curData:self->_currentFrameData];
        } else {
            [self _addConsumerWithDataLength:extra_bytes_needed callback:^(SRWebSocket *self, NSData *data) {
                size_t mapped_size = data.length;
                #pragma unused (mapped_size)
                const void *mapped_buffer = data.bytes;
                size_t offset = 0;
                
                if (header.payload_length == 126) {
                    assert(mapped_size >= sizeof(uint16_t));
                    uint16_t newLen = EndianU16_BtoN(*(uint16_t *)(mapped_buffer));
                    header.payload_length = newLen;
                    offset += sizeof(uint16_t);
                } else if (header.payload_length == 127) {
                    assert(mapped_size >= sizeof(uint64_t));
                    header.payload_length = EndianU64_BtoN(*(uint64_t *)(mapped_buffer));
                    offset += sizeof(uint64_t);
                } else {
                    assert(header.payload_length < 126 && header.payload_length >= 0);
                }
                
                if (header.masked) {
                    assert(mapped_size >= sizeof(_currentReadMaskOffset) + offset);
                    memcpy(self->_currentReadMaskKey, ((uint8_t *)mapped_buffer) + offset, sizeof(self->_currentReadMaskKey));
                }
                
                [self _handleFrameHeader:header curData:self->_currentFrameData];
            } readToCurrentFrame:NO unmaskBytes:NO];
        }
    } readToCurrentFrame:NO unmaskBytes:NO];
}

最后编辑于：2017.12.09 02:23:09

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SocketRocket研究三 协议数据封装

socket是一种http的长连接请求，只是发送的数据格式要符合协议标准

读取数据

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SocketRocket研究三协议数据封装