Hi, I built small test server application using lwip stack to work like echo server . i tried to associate the socket with a stream by using fdopen but it failed . when i using the mode "r" or "r+" it give invalid parameter error, in the same time when i try to write on the file descriptor returned by lwip_accept it is write to the client . the part of code is : while (1) { magsock = lwip_accept (socket_v , 0, 0 ); if (magsock ==-1) { perror ("lwip_accept"); } else { // this is work char *buf= "hi"; if( write (,magsock,buf , sizeof(buf) )<0) { perror ("write"); } // this is not work FILE *file; file= fdopn(magsock ,"r"); if (file==NULL) { perror ("fdopn");
} int c ; while(c=fgetc(file)) printf(c); fclose(file); } } any clue or suggestion ?
best, --
Hello,
On 04/18/2014 10:03 AM, Mhamad Hmad wrote:
Hi, I built small test server application using lwip stack to work like echo server . i tried to associate the socket with a stream by using fdopen but it failed . when i using the mode "r" or "r+" it give invalid parameter error, in the same time when i try to write on the file descriptor returned by lwip_accept it is write to the client .
I am not proficient with using 'fdopen' on Genode but I see a glaring problem in your code:
You are mixing the lwip_* functions with libc functions to which you pass lwIP socket descriptors as arguments. The problem is that the C runtime (which provides 'fdopen') is not aware of any file descriptors of the lwIP library. The lwIP socket descriptors and libc's file descriptors are different name spaces.
Fortunately there is a solution to bridge the gap between lwIP and the C runtime. Using the 'libc_lwip_nic_dhcp' libc plugin, you can use the normal BSD socket interface instead of the lwIP interface. So instead of 'lwip_accept', just use 'accept'. The pluging wraps the 'lwip_*' functions and creates a proper libc file descriptor for each lwIP socket descriptor. The descriptors returned from those functions are consistent with the name space of the C runtime. I.e., they can be specified as arguments to 'select', and hopefully also to 'fdopen'.
Best regards Norman
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Mhamad Hmad -
Norman Feske