objective-c - 使用 GCDAsyncSocket 通过套接字远程登录

Question

我正在尝试通过 telnet 从 objective-c 连接到 Cisco C40 编解码器。在我的计算机上使用终端时，我得到:

Password:

然而，当进行套接字连接时，需要进行 telnet 协商。我是，但由于某种原因，我无法进入上面的“密码:”提示。

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSLog(@"RECEIVE BUFFER %@",data);

    //store read bytes to rawData
    self.rawData = [[NSMutableData alloc] initWithData:data];

    //cast bytes
    const uint8_t *bytes = [self.rawData bytes];

    //go through rawdata format and save it to networkbuffer
    for (int i =0; i < [self.rawData length]; i++)
    {
        if (![[NSString stringWithFormat:@"%02X", bytes[i]]isEqual:@"0D"])
        {
            [self.networkBuffer addObject:[NSString stringWithFormat:@"%02X", bytes[i]]];
        }
    }

    //negotiate any telnet protocal stuff (just accept options )
    //example:
    //FF:FD:18 returns FF:FB:18
    while([[self.networkBuffer objectAtIndex:0]isEqualToString:@"FF"] && [[self.networkBuffer objectAtIndex:1]isEqualToString:@"FD"] ) {
//        NSLog(@"HERE");

        NSData * tempData =[data subdataWithRange:NSMakeRange(0, 3)];

        NSMutableData * tempMutData = [NSMutableData dataWithData:tempData];

        const unsigned char replacement[] = {
                0xFC
            };

        [tempMutData replaceBytesInRange:NSMakeRange(1, 1) withBytes:replacement];

        [self sendCommand:tempMutData];

        data = [data subdataWithRange:NSMakeRange(3, [data length]-3)];

        self.networkBuffer = [NSMutableArray arrayWithArray:[self.networkBuffer subarrayWithRange:NSMakeRange(3, [self.networkBuffer count]-3)]];

//        NSLog(@"network buffer after removal: %@", data);

        if ([self.networkBuffer count]<3) {
            [self.networkBuffer insertObject:@" " atIndex:0];
        }
    }

    //decode from bytes to text
    for ( NSString * component in self.networkBuffer)
    {
        int value = 0;
        sscanf([component cStringUsingEncoding:NSASCIIStringEncoding], "%x", &value);
        [self.dataString appendFormat:@"%c", (char)value];
        NSLog(@"data byte: %c",(char)value);
    }
    [self telnetResponse:self.dataString];

    [self.networkBuffer removeAllObjects];
    [self.socket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];//CRLFData
}

这是我接收和发送的 telnet 协商选项的分割:

服务器发送给我:

FF,FD,18 (0x18 = 24dec) (做终端类型)

FF,FD,20 (0x20 = 32dec) (做终端速度)

FF,FD,23 (0x23 = 35dec) (Do X 显示位置)

FF,FD,27 (0x27 = 39dec)(做新环境选项)

我尝试的响应无效(没有进一步输入的提示):

FF,FC,18 (0x18 = 24dec)(不会是终端类型)

FF,FC,20 (0x20 = 32dec)(不会是终端速度)

FF,FC,23 (0x23 = 35dec) (Wont X Display Location)

FF,FC,27 (0x27 = 39dec)(不需要新环境选项)

如果您查看代码，您会看到我正在检查 FF，如果是，则用类似的字节进行响应(用 FC 替换 FD)，希望不会接受这些选项，但这似乎不起作用。

对我有帮助的链接:

https://stackoverflow.com/a/2913991/530933

Telnet IAC commands (NSStream socket)

http://www.iprodeveloper.com/forums/aft/52910

更新

我用命令 shell 和 cisco 编解码器做了一个 wireshark。之后我复制了那些协商设置/数据包。现在唯一的问题是我只得到回声。所以我什么也得不到，发送命令，然后返回提示和我的文本。 (例如，一无所获 - 发送用户名“admin” - 返回“登录名:admin”)因此我的意思是只得到回声。我应该得到提示“登录:”然后发送“管理员”然后它应该提示我输入密码。

这是我在连接时发送的协商选项:

//will terminal type
    //will negotiate about window size
    const unsigned char nineteen[] = {
        0xFF, 0xFB, 0x18, 0xFF, 0xFB, 0x1F
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:nineteen length:sizeof(nineteen)];
    [self sendCommand:self.dataToBeSent];

    //wont terminal speed
    //wont X display location
    //will new environment option
    const unsigned char twenty[] = {
        0xFF, 0xFC, 0x20, 0xFF, 0xFC, 0x23, 0xFF, 0xFB, 0x27
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twenty length:sizeof(twenty)];
    [self sendCommand:self.dataToBeSent];

    //Suboption being: negotiate about window size
    //end
    const unsigned char twentyOne[] = {
        //0xFF,0xFC, 0x18
        0xFF, 0xFA, 0x1F, 0x00, 0x50, 0x00, 0x19, 0xFF, 0xF0
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentyOne length:sizeof(twentyOne)];
    [self sendCommand:self.dataToBeSent];

    //new enviroment option
    //end
    const unsigned char twentyThree[] = {
        0xFF,0xFA, 0x27, 0x00, 0xFF, 0xF0
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentyThree length:sizeof(twentyThree)];
    [self sendCommand:self.dataToBeSent];

    //Terminal Type (ANSI)
    //end
    const unsigned char twentySeven[] = {
        0xFF,0xFA, 0x18, 0x00, 0x41, 0x4E, 0x53, 0x49, 0xFF, 0xF0
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentySeven length:sizeof(twentySeven)];
    [self sendCommand:self.dataToBeSent];

    //do suppress go ahead
    const unsigned char twentyEight[] = {
        0xFF, 0xFD, 0x03
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentyEight length:sizeof(twentyEight)];
    [self sendCommand:self.dataToBeSent];

    //will echo
    //dont status
    //wont remote flow control
    const unsigned char twentyFour[] = {
        0xFF, 0xFB, 0x01, 0xFF, 0xFE, 0x05, 0xFF,0xFC, 0x21
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentyFour length:sizeof(twentyFour)];
    [self sendCommand:self.dataToBeSent];

    //wont echo
    const unsigned char twentyFive[] = {
        0xFF, 0xFC, 0x01
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentyFive length:sizeof(twentyFive)];
    [self sendCommand:self.dataToBeSent];

    //Do echo
    const unsigned char twentySix[] = {
        0xFF,0xFD, 0x01
    };
    self.dataToBeSent = [[NSData alloc]initWithBytes:twentySix length:sizeof(twentySix)];
    [self sendCommand:self.dataToBeSent];

Answer 1

所以一个大问题来自提示(登录名:或密码:)没有以 CR NL (0D:0A) 结尾的行。而我在做

[self.socket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];

所以我从来没有阅读过提示的数据(一个大问题是 wireshark 没有工作(fixed that myself too))。弄清楚这一点后，我将上面的行更改为:

[self.socket readDataWithTimeout:-1 tag:0];

这成功地给了我我的提示。以下是我为达到这一点而发送的谈判以及原始问题所涉及的内容(与更新中的上述内容相同):

will terminal type - 0xFF, 0xFB, 0x18

will negotiate about window size - 0xFF, 0xFB, 0x1F

wont terminal speed - 0xFF, 0xFC, 0x20

wont X display location - 0xFF, 0xFC, 0x23

will new environment option - 0xFF, 0xFB, 0x27

Suboptions

 negotiate about window size - 0xFF, 0xFA, 0x1F, 0x00, 0x50, 0x00, 0x19
 end - 0xFF, 0xF0

 new enviroment option - 0xFF,0xFA, 0x27, 0x00, 
 end - 0xFF, 0xF0

 Terminal Type (ANSI) -  0xFF,0xFA, 0x18, 0x00, 0x41, 0x4E, 0x53, 0x49, 
 end - 0xFF, 0xF0

do suppress go ahead - 0xFF, 0xFD, 0x03

will echo - 0xFF, 0xFB, 0x01

不要状态 - 0xFF、0xFE、0x05

不会远程流量控制 - 0xFF、0xFC、0x21

不会回显 - 0xFF、0xFC、0x01

Do echo - 0xFF,0xFD, 0x01

这也可能有所帮助。它从流中删除协商字节，因此当您编码以生成字符串时，它不包含协商字节。

while([[self.networkBuffer objectAtIndex:0]isEqualToString:@"FF"])
    {
        if ([[self.networkBuffer objectAtIndex:1]isEqualToString:@"FD"] || [[self.networkBuffer objectAtIndex:1]isEqualToString:@"FB"] || [[self.networkBuffer objectAtIndex:1]isEqualToString:@"FE"] || [[self.networkBuffer objectAtIndex:1]isEqualToString:@"FA"]) {

            //most negotiation options are 3 bytes long
            int indexToRemoveFromBuffer = 3;

            //if FA then they are longer then 3 bytes
            if ([[self.networkBuffer objectAtIndex:1]isEqualToString:@"FA"]) {
                //look for indicator of END (F0)
                indexToRemoveFromBuffer = [self.networkBuffer indexOfObject:@"F0"]+1;

            }

            //remove these bytes from networkbuffer
            self.networkBuffer = [NSMutableArray arrayWithArray:[self.networkBuffer subarrayWithRange:NSMakeRange(indexToRemoveFromBuffer, [self.networkBuffer count]-indexToRemoveFromBuffer)]];

            if ([self.networkBuffer count] == 0) {
                if (self.isLoggedIn) {
                    [self.socket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];//CRLFData
                }else{
                    [self.socket readDataWithTimeout:-1 tag:0];
                }
                return;
            }
        }else{
            break;
        }
}