CODEWITHSUNDEEP
c++jsonwindowsgoogle-chrome-extensionchrome-native-messaging
Min Yang
Min Yang

Reputation: 59

Chrome Extension using NativeMessaging cannot receive some kind of json data

Chrome extension use native messaging to receive json data:

var port = chrome.runtime.connectNative('company.my_application');  
port.onMessage.addListener(function(result) { 
    console.log(result);
});

In my C++ program, if I send a json string str1[], extension can receive it, but if I send str2[], extension can not receive it. Is there any problem with this string?

str2[] stands for a long string which is a correct Json data, but can't be accepted by extension.
Did any one run into the same problem and resolve it ?

char str1[]="{\"Func\":\"test\",\"msg\":\"hello\"}";

char str2[]="{\"Func\":\"test\",\"msg\":\"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\"}";

I'm trying to send the length and message as follows:

size_t len = strlen(str2);
cout.write(str2, len);
fflush(stdout);

I have use these ways to send length:

    cout.write((char*)&len, 4);

    putchar ((( char *) &len) [0]);
    putchar ((( char *) &len) [1]);
    putchar ((( char *) &len) [2]);
    putchar ((( char *) &len) [3]);

    putchar(char(((len >> 0) & 0xFF)));
    putchar(char(((len >> 8) & 0xFF)));
    putchar(char(((len >> 16) & 0xFF)));
    putchar(char(((len >> 24) & 0xFF)));

Upvotes: 1

Views: 200

Answers (2)

jam
jam

Reputation: 3688

[OP's solution converted to answer below]

Thanks everyone for comments, I have now fixed this problem.

Cause:

The length of str[] is 2601(0x29 0x0a 0x00 0x00). My IO will automatically insert Ox0d before 0x0a, so my ouput length become 5 bytes, (0x29 0x0d 0x0a 0x00 0x00).

Solution:

Change IO mode.

#include<io.h>
#include<fcntl.h>
_setmode(fileno(stdout), O_BINARY);

Upvotes: 1

Rob W
Rob W

Reputation: 348992

You should use

unsigned int len = strlen(str2);

instead of

size_t len = strlen(str2);

The native messaging protocol requires that the message is preceded by a 32-bit integer, whereas the bit size of size_t is implementation-dependent. On my 64-bit system, sizeof(size_t) is 8 (bytes) for example.

Upvotes: 1

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