How to send a uint8_t through a socket

[iceman]

Hi,
I am having a varible in a structure as uint8_t
eg
struct eg
{
uint8_t a;
uint16_t b;
}
I send this I use htons for uint16 to align it .I left uint8_as it
is.But, when I sent it through the socket.
but I get only garbage on the other side

Cheers,
Jegan

[iceman]

Hi,
Here is the code.The value of b in the struc is going through but not
a .when i print it in the server side..nothing is getting printed.
I changed the code a little[from the first post so htons/ntonl is
used]
struct exam
{
uint8_t b;
uint32_t a;
};

////////////////////////////////////server
int main()
{
int listenSocket, connectSocket, i;
unsigned short int listenPort;
socklen_t clientAddressLe ngth;
struct sockaddr_in clientAddress, serverAddress;
char line[LINE_ARRAY_SIZE];

cout << "Enter port number to listen on (between 1500 and 65000): ";
cin >listenPort;

// Create socket for listening for client connection requests.
listenSocket = socket(AF_INET, SOCK_STREAM, 0);
if (listenSocket < 0) {
cerr << "cannot create listen socket";
exit(1);
}

serverAddress.s in_family = AF_INET;
serverAddress.s in_addr.s_addr = htonl(INADDR_AN Y);
serverAddress.s in_port = htons(listenPor t);

if (bind(listenSoc ket,
(struct sockaddr *) &serverAddre ss,
sizeof(serverAd dress)) < 0) {
cerr << "cannot bind socket";
exit(1);
}
`
// Wait for connections from clients.
listen(listenSo cket, 5);

while (1) {
cout << "Waiting for TCP connection on port " << listenPort <<
" ...\n";

clientAddressLe ngth = sizeof(clientAd dress);
connectSocket = accept(listenSo cket,
(struct sockaddr *) &clientAddre ss,
&clientAddressL ength);
if (connectSocket < 0) {
cerr << "cannot accept connection ";
exit(1);
}

// Show the IP address of the client.
cout << " connected to " << inet_ntoa(clien tAddress.sin_ad dr);

char x[123];
exam *o;
while (recv(connectSo cket,x,sizeof(e xam), 0) 0) {

cout <<((exam *)x)->a<<"\n";
cout <<((exam *)x)->b<<"\n";
}
}

////////////////////client

int main()
{
int socketDescripto r;
unsigned short int serverPort;
struct sockaddr_in serverAddress;
struct hostent *hostInfo;
char buf[MAX_LINE + 1], c;
uint8_t flag=3;
buf[0]=flag;

cout << "Enter server host name or IP address: ";
cin.get(buf, MAX_LINE, '\n');
hostInfo = gethostbyname(b uf);
if (hostInfo == NULL) {
cout << "problem interpreting host: " << buf << "\n";
exit(1);
}

cout << "Enter server port number: ";
cin >serverPort;
cin.get(c); // dispose of the newline

socketDescripto r = socket(AF_INET, SOCK_STREAM, 0);
if (socketDescript or < 0) {
cerr << "cannot create socket\n";
exit(1);
}

serverAddress.s in_family = hostInfo->h_addrtype;
memcpy((char *) &serverAddress. sin_addr.s_addr ,
hostInfo->h_addr_list[0], hostInfo->h_length);
serverAddress.s in_port = htons(serverPor t);

if (connect(socket Descriptor,
(struct sockaddr *) &serverAddre ss,
sizeof(serverAd dress)) < 0) {
cerr << "cannot connect\n";
exit(1);
}
exam *t1,t2;
t1=&t2;;
t2.a=21;

t2.b=1;
unsigned char x[10];
char *y=(char *)&t2;

// Stop when the user inputs a line with just a dot.

// Send the line to the server.
if (send(socketDes criptor,y,sizeo f(exam), 0) < 0) {
cerr << "cannot send data ";
close(socketDes criptor);
exit(1);
}

}

return 0;

}

[iceman]

the words in the bracket are supposed to read
[from the first post so htons/ntonl is
NOT used]

[iceman]

here is the output from the server side

Enter port number to listen on (between 1500 and 65000): 1234
Waiting for TCP connection on port 1234 ...
connected to 127.0.0.1:33508
21

Waiting for TCP connection on port 1234 ...

[Christopher]

On Jan 22, 9:32 pm, iceman <jegan...@gmail .comwrote:

here is the output from the server side

Enter port number to listen on (between 1500 and 65000): 1234
Waiting for TCP connection on port 1234 ...
connected to 127.0.0.1:33508
21

Waiting for TCP connection on port 1234 ...

That's good stuff. Now all you have to do is consolidate your 4 posts
and start a thread on one of the other newsgroups I mentioned.
I think you missed the _T_ in the "post there" part of my original
reply.

[Martin Vuille]

iceman <je******@gmail .comwrote in
news:e5******** *************** ***********@i29 g2000prf.google grou
ps.com:

cout <<((exam *)x)->b<<"\n";

If I am not mistaken this will cause b to be output
as an ASCII character rather than as a decimal value.
Since ASCII 1 is not a printable character, you see
nothing in the output.

MV

[iceman]

On Jan 23, 3:59 pm, Martin Vuille <jpm...@yahoo.c omwrote:

iceman <jegan...@gmail .comwrote innews:e5****** *************** *************@i 29g2000prf.goog legrou
ps.com:

cout <<((exam *)x)->b<<"\n";

If I am not mistaken this will cause b to be output
as an ASCII character rather than as a decimal value.
Since ASCII 1 is not a printable character, you see
nothing in the output.

MV

yep..that was the prob..

thanks for your help..

[Gerhard Fiedler]

On 2008-01-23 00:58:37, Christopher wrote:

This post is OT here.

and

>That's good stuff. Now all you have to do is consolidate your 4 posts
and start a thread on one of the other newsgroups I mentioned. I think
you missed the _T_ in the "post there" part of my original reply.

In regards to this:

>cout <<((exam *)x)->b<<"\n";

If I am not mistaken this will cause b to be output as an ASCII
character rather than as a decimal value.

Is this really OT here?

Gerhard

[James Kanze]

On Jan 23, 12:38 pm, Gerhard Fiedler <geli...@gmail. comwrote:

On 2008-01-23 00:58:37, Christopher wrote:

This post is OT here.

and

That's good stuff. Now all you have to do is consolidate your 4 posts
and start a thread on one of the other newsgroups I mentioned. I think
you missed the _T_ in the "post there" part of my original reply.

In regards to this:

cout <<((exam *)x)->b<<"\n";

If I am not mistaken this will cause b to be output as an ASCII
character rather than as a decimal value.

Is this really OT here?

No. Nor are some of the other issues with his code (like the
undefined padding the struct might contain). But his original
question was formulated in a way which would probably make it
seem system dependent.

--
James Kanze (GABI Software) email:ja******* **@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[Daniel T.]

iceman <je******@gmail .comwrote:

I am having a varible in a structure as uint8_t
eg
struct eg
{
uint8_t a;
uint16_t b;
}
I send this I use htons for uint16 to align it .I left uint8_as it
is.But, when I sent it through the socket.
but I get only garbage on the other side

Here's something to think about...

int main() {
cout << sizeof( eg ) << '\n';
cout << sizeof( uint8_t ) << '\n';
cout << sizeof( uint16_t ) << '\n';
}

On my machine the output is 4, 1 and 2... What does that tell us?