C: convert char buffer received from socket to host endianess buffer

kpachopoulos · 06-07-2007, 01:31 PM

Hi,
i receive a buffer from a socket (a char one) and i want to process it. The buffer is probably in "network byte order". How do i change -if there is need to- its byte order? Is there something like htons and ntohs, but for the whole char buffer?

Thanks

traene · 06-07-2007, 04:48 PM

Good questions. Endian-ness is important for numbers. (maybe for multibyte character sequences also, i am not sure.) Can you tell what kind of data you are recieving? If it's just a character sequence you may give them out with printf and check.

kpachopoulos · 06-07-2007, 05:01 PM

I am receiving a TFTP packet and i want to read its fields:

Code:

            2 bytes     string    1 byte     string   1 byte
            ------------------------------------------------
           | Opcode |  Filename  |   0  |    Mode    |   0  |
            ------------------------------------------------

For example i would like to read the filename.

traene · 06-07-2007, 05:06 PM

You may do it like this:

Code:

char buf[1024];
read(sockfd, buf, 1024);
char* pbuf=buf;
short hboOpcode=ntohs((short)pbuf);
pbuf+=2;
int lens1=strnlen(pbuf,MAX_LEN);
// copy the string..
pbuf+=lenst+1;
int lenst2=strnlen(pbuf,MAX_LEN);