Hi,

I am currently writing a simple gnutella client as my thesis. But I am
stucked at the moment. My question might not be of common interest. If so please state do you know any list or forum to ask for help.

Anyway,

I have used Gnutella protocol draft at rfc-gnutella.sourceforge.net. So far
I have achieved connecting to the network using GnuWebCaches. I receive a
200 OK messega from a connected client. So up to this point everything must
be fine. But then I send a ping message and wait for a pong. But nothing is
received. Only send returns 0.

My C code,

struct ping_header
{
char GUID[16];
char Payload_Type;
char TTL;
char Hops;
char Payload_Len[4];
};

struct ping_header *get_ping_header(void)
{
struct ping_header *p_head;

p_head = (struct ping_header *)malloc(sizeof(struct ping_header));
p_head = (struct ping_header *)malloc(sizeof(struct ping_header));

strcpy(p_head->GUID,"jhwerdkrodmwjydh");
p_head->Payload_Type = '0';
p_head->TTL = '2';
p_head->Hops = '0';
strcpy(p_head->Payload_Len,"0");

return p_head;
}
...
...
send(sockfd, get_ping_header(), sizeof(struct ping_header), 0);
memset(buf, '\0', 1024);
while (1)
{
i = recv(sockfd, buf, 1024, 0);
if(i>=0)
{
printf("\n<%d> bytes data received\n", i);
printf("\nPing is answered as %s\n", buf);
}
}


Kaan Coskun

1) You should use char as bytes and not as characters.
I mean, you send the character "0" as payload Type.
But the char "0" as not the byte value 0x00 that is the type of a ping. So send 0x00 instead of "0". You should act like this for all the other fields.

2) in you message you say you receive OK from a remote client. Have you send OK too as the draft speficy it (section handshake) before send the ping?

Hope this could be helpful
regards,

__________________
-- There are 10 kind of people, those who understand binary and those who don't --

Thanks for your help. It was very helpfull. It turned out to be that my payload_length field should be an integer not a char array.

Here is the solution,

struct ping_header
{
char GUID[16];
char Payload_Type;
char TTL;
char Hops;
int Payload_Len; <------------
};

struct ping_header *get_ping_header(void)
{
struct ping_header *p_head;

p_head = (struct ping_header *)malloc(sizeof(struct ping_header));

strcpy(p_head->GUID,"jhwerdkrodmwjydh");
p_head->Payload_Type = '0';
p_head->TTL = '2';
p_head->Hops = '0';
p_head->Payload_Len = 0; <------------

return p_head;
}



But I had another issue. So I was not able to even try the advisory. The clients I received from the GnuWebCaches didn't seem to be accepting me anymore. They generally responded 503 Gnutella unavaible. Is it normal. I guess I am in a ban list or something like that.

okay, be just careful that an int can be different that 4 bytes on somes machines and langages. (for instance an integer can be 16 or 32 bits long...)
Did you receive Pongs?

I don't think your Payload_type field is right. You have:
char Payload_Type;
...
and:
p_head->Payload_Type = '0';


but the char '0' as you write has as ASCII Code 0x30 and not 0x00
so code instead:
p_head->Payload_Type = 0x00;

Concerning the non responding hosts and clients, i have exactly the same problem with the client I develop. Nearly all the servents are busy, and it's a real problem

__________________
-- There are 10 kind of people, those who understand binary and those who don't --

Once you support Ultrapeer it will get easier to connect since many servents deny peer connections due it's bigger traffic.
Worked out for me.

__________________
Never touch a running system.
www.guox.de

I was mistaken with that I received any pongs. I just received a ping request from the servant.

I have changed the payload type. But still seem to be there is a problem. I receive nothing.

If you have your code I would be grateful to see the basic parts that handles sending and receiving pings. Altough I know only C I think I shouldn't mind seeing codes written in other languages.

zomlakNO@SPAMhotmail.com, kcoskunNO@SPAMknuth.cs.bilgi.edu.tr