CODEWITHSUNDEEP
google-nativeclient
redleo85
redleo85

Reputation: 249

pNaCl UDP Client getaddrinfo Function not implemented - untrusted code

I'm trying to write a google native client (pNacl) module. The Client is supposed to get some data from a remote server.
The calling of the function from the module works fine.
I'm at the very beginning and cannot manage to make the client send any data at all. Even a very basic lookup of the IP address with getaddrinfo does not work.
When I dump the network traffic with wireshark, I can see that no packets are being sent. The errno refers to getaddrinfo with "Function not implemented." Even this simple code won't work. It does work though as a stand alone client, not as a native client module.
The browser also gives an error:
** Signal 4 from untrusted code: pc=6d98000b3360

Does anybody have a clue what I'm doing wrong?

#include <stdio.h> 
#include <string.h> 
#include <stdlib.h> 
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <errno.h>

void foo(){

    int rc;
    struct addrinfo hints, *info;

    memset(&hints, 0, sizeof(hints));

    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_family = AF_INET;

    fprintf(stderr, "Trying: www.google.com\n");
    rc = getaddrinfo("www.google.com", "80", &hints, &info);
    if(rc != 0) {
        fprintf(stdout, "getaddrinfo: %s\n", gai_strerror(rc));
        fprintf(stdout, "Error: %s\n", strerror(errno));
    }
    freeaddrinfo(info);
}

Upvotes: 0

Views: 108

Answers (2)

redleo85
redleo85

Reputation: 249

So I got it working after all. Main problem was, that the function was called on the main thread. I used nacl_io library, which has to be called in a background thread and which needed to be properly initialised with nacl_io_init_ppapi(...). The initialisation via nacl_io_init() did not work for some reason.

So I added both to the constructor of the pp::Instance class. Adding the thread inside of function foo() did not work either. Looks like it has to be called at the beginning.

#include <pthread.h>
#include <nacl_io.h>
...

pthread_t handle_msg_thread;
void *handleMsgThreadFunc(void * data);   // Calls function foo()

class MyInstance : public pp::Instance {
  public:
    explicit MyInstance(PP_Instance instance) :pp::Instance(instance) {
       nacl_io_init_ppapi(instance, pp::Module::Get()->get_browser_interface());
       pthread_create(&handle_msg_thread, NULL, &handleMsgThreadFunc, NULL);
    }
    ...
}

Upvotes: 1

bbudge
bbudge

Reputation: 1137

Your network access is going through the NaClIO layer, which calls PPAPI (Pepper Plugin API) in its implementation. These APIs require special permissions - TCP/UDP is not exposed to the open web for security reasons.

See this thread: https://groups.google.com/forum/#!topic/native-client-discuss/NmIUvpLZ1uI

Upvotes: 0

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