/* The user typed in a C<addr>:<port> command to connect to a peer.
*/
static void connect_command(struct file_info *fi, char *addr_port){
void try_connect(struct file_info *fi);
if (fi->type != FI_FILE) {
fprintf(stderr, "unexpected connect message\n");
return;
}
char *p = index(addr_port, ':');
if (p == 0) {
fprintf(stderr, "do_connect: format is C<addr>:<port>\n");
return;
}
*p++ = 0;
struct sockaddr_in addr;
if (addr_get(&addr, addr_port, atoi(p)) < 0) {
return;
}
*--p = ':';
fi = file_info_add(FI_OUTGOING, -1, 0, 0);
fi->u.fi_outgoing.status = FI_CONNECTING;
/* Even though we're connecting, you're allowed to connect using any address to
* a peer (including a localhost address). So we have to wait for the Hello
* message until we're certain who it is on the other side. Until then, we keep
* the address we know for debugging purposes.
*/
fi->addr = addr;
try_connect(fi);
}
struct sockaddr_in* string_to_addr(char* string) {
char *port = index(string, ':');
*port++ = 0;
struct sockaddr_in* addr = calloc(1, sizeof(struct sockaddr_in));
addr_get(addr, string, atoi(port));
*--port = ':';
return addr;
}
/* Received a H(ello) message of the form H<addr>:<port>. This is the first message
* that's sent over a TCP connection (in both directions) so the peers can identify
* one another. The port is the server port of the endpoint rather than the
* connection's port.
*
* Sometimes accidentally peers try to connect to one another at the same time.
* This code kills one of the connections.
*/
void hello_received(struct file_info *fi, char *addr_port){
char *p = index(addr_port, ':');
if (p == 0) {
fprintf(stderr, "do_hello: format is H<addr>:<port>\n");
return;
}
*p++ = 0;
struct sockaddr_in addr;
if (addr_get(&addr, addr_port, atoi(p)) < 0) {
return;
}
*--p = ':';
printf("Got hello from %s:%d on socket %d\n", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port), fi->fd);
/* If a connection breaks and is re-established, a duplicate hello message is likely
* to arrive, but we can ignore it as we already know the peer.
*/
if (fi->status == FI_KNOWN) {
fprintf(stderr, "Duplicate hello (ignoring)\n");
if (addr_cmp(addr, fi->addr) != 0) {
fprintf(stderr, "do_hello: address has changed???\n");
}
return;
}
/* It is possible to set up a connection to self. We deal with it by ignoring the
* Hello message but keeping the connection established.
*/
if (addr_cmp(addr, my_addr) == 0) {
fprintf(stderr, "Got hello from self??? (ignoring)\n");
return;
}
/* Search the connections to see if there is already a connection to this peer.
*/
struct file_info *fi2;
for (fi2 = file_info; fi2 != 0; fi2 = fi2->next) {
if (fi2->type == FI_FREE || fi2->status != FI_KNOWN) {
continue;
}
if (addr_cmp(fi2->addr, addr) != 0) {
continue;
}
/* Found another connection. We're going to keep just one. First see if
* this is actually an existing connection. It may have broken.
*/
if (fi2->fd == -1) {
printf("Found a defunct connection---dropping that one\n");
if (fi2->type == FI_OUTGOING) {
fi->type = FI_OUTGOING;
fi->u.fi_outgoing = fi2->u.fi_outgoing;
}
fi2->type = FI_FREE;
return;
}
/* Of the two, we keep the "lowest one". We identify a connection by the lowest
* endpoint address.
*/
struct sockaddr_in mine, other;
get_id(fi->fd, &mine);
get_id(fi2->fd, &other);
if (addr_cmp(mine, other) < 0) {
/* We keep mine.
*/
printf("duplicate connection -- keep mine\n");
if (fi2->type == FI_OUTGOING) {
fi->type = FI_OUTGOING;
fi->u.fi_outgoing = fi2->u.fi_outgoing;
}
close(fi2->fd);
fi2->type = FI_FREE;
}
else {
printf("duplicate connection -- keep other\n");
/* The other one wins.
*/
if (fi->type == FI_OUTGOING) {
fi2->type = FI_OUTGOING;
fi2->u.fi_outgoing = fi->u.fi_outgoing;
}
close(fi->fd);
fi->type = FI_FREE;
return;
}
}
/* No other connection. Keep this one.
*/
printf("New Connection\n");
fi->addr = addr;
fi->status = FI_KNOWN;
if(!nl)
{
nl = (struct node_list *) nl_create();
char *my_addr_str = addr_to_string(my_addr);
nl_add(nl, my_addr_str);
free(my_addr_str);
}
char *addr_str = addr_to_string(addr);
nl_add(nl, addr_str);
free(addr_str);
updateGraph();
send_gossip();
}
