QCommandLineConnection.m

/*
    File:       QCommandLineConnection.m

    Contains:   Manages a connection consisting of CR LF delimited lines.

    Written by: DTS

    Copyright:  Copyright (c) 2011 Apple Inc. All Rights Reserved.

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*/

#import "QCommandLineConnection.h"

@implementation QCommandLineConnection

@synthesize commandDelegate = commandDelegate_;

#pragma mark * Overrides

// See comment in header for an explanation of what these routines are about.

- (void)willCloseWithError:(NSError *)error
{
    // error may be nil
    if ([self.commandDelegate respondsToSelector:@selector(commandLineConnection:willCloseWithError:)]) {
        [self.commandDelegate commandLineConnection:self willCloseWithError:error];
    }
    [super willCloseWithError:error];
}

- (void)logWithFormat:(NSString *)format arguments:(va_list)argList
{
    assert(format != nil);
    if ([self.commandDelegate respondsToSelector:@selector(commandLineConnection:logWithFormat:arguments:)]) {
        [self.commandDelegate commandLineConnection:self logWithFormat:format arguments:argList];
    }
    [super logWithFormat:format arguments:argList];
}

#pragma mark * Send

- (void)sendString:(NSString *)str
{
    assert(str != nil);
    [self sendCommand:[str dataUsingEncoding:NSUTF8StringEncoding]];
}

- (void)sendCommandLine:(NSString *)line
{
    assert(line != nil);
    [self sendString:[NSString stringWithFormat:@"%@\r\n", line]];
}

- (void)sendCommandLines:(NSArray *)lines
{
    NSString *  linesStr;

    assert(lines != nil);
    assert([lines count] != 0);
    
    if ([lines count] == 1) {
        assert( [[lines objectAtIndex:0] isKindOfClass:[NSString class]] );
        [self sendCommandLine:[lines objectAtIndex:0]];
    } else {
        linesStr = [NSString stringWithFormat:@"%@\r\n", [lines componentsJoinedByString:@"\r\n"]];
        assert(linesStr != nil);
        [self sendString:linesStr];
    }
}

#pragma mark * Parse

- (void)didReceiveCommandLine:(NSString *)commandLine
    // See comment in header.
{
    assert(commandLine != nil);
    
    if ( [self.commandDelegate respondsToSelector:@selector(commandLineConnection:didReceiveCommandLine:)] ) {
        [self.commandDelegate commandLineConnection:self didReceiveCommandLine:commandLine];
    }
}

- (NSUInteger)parseCommandData:(NSData *)commandData
    // Called by our superclass when data arrives.  We parse command lines out 
    // of the data buffer and pass them to our delegate, returning the number of 
    // bytes successfully parsed.
    //
    // Note: Earlier versions of this code used to call [super parseCommandData], 
    // to given the super class's delegate a crack at the data before we had a go. 
    // We no longer do this because our super class now fails 
    // kQCommandConnectionInputUnexpectedError if its delegate doesn't implement 
    // -connection:parseCommandData:.
{
    const uint8_t *     bufferBytes;
    NSUInteger          bufferLength;
    NSUInteger          offset;
    NSUInteger          cursor;
    NSError *           error;

    assert(commandData != nil);
    
    bufferBytes  = [commandData bytes];
    bufferLength = [commandData length];

    assert(bufferBytes != nil);
    assert(bufferLength != 0);
    
    offset = 0;
    error  = nil;
    do {
        assert(offset <= bufferLength);
        
        cursor = offset;
        while ( (cursor < bufferLength) && (bufferBytes[cursor] != '\n') ) {
            cursor += 1;
        }
        if (cursor == bufferLength) {
            // We got to the end of the buffer before we found a line ending. 
            // We return in this case.  We'll get called back when more data 
            // arrives (or the connection will fail if the command line is 
            // longer than our input buffer).
            break;
        } else {
            NSString *  commandLine;
            
            cursor += 1;        // include the LF in the command

            // Check that the command string is valid UTF-8 and that it's correctly terminated 
            // by CR LF.  If either of these fails, we just drop the connection.  It's brutal, 
            // but it's the only thing we can do at this layer (because we don't know how to 
            // format a 'you bozo' response and we don't want to pass malformed commands up 
            // to our delegate and an extra delegate callback to deal with this seems somewhat 
            // excessive).
            
            commandLine = [[NSString alloc] initWithBytes:&bufferBytes[offset] length:cursor - offset encoding:NSUTF8StringEncoding];
            if ( (commandLine == nil) || ( ([commandLine length] < 2) || ([commandLine characterAtIndex:[commandLine length] - 2] != '\r') ) ) {
                error = [[self class] errorWithCode:kQCommandConnectionInputCommandMalformedError];
            } else {
                [self didReceiveCommandLine:commandLine];
            }
            [commandLine release];
        
            if (error != nil) {
                break;
            } else {
                offset = cursor;
            }
        }
    } while (YES);

    if (error != nil) {
        [self closeWithError:error];
    }
    
    return offset;
}

@end