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#include <u.h>
#include <libc.h>
#include <ip.h>
#include <mp.h>
#include <libsec.h>
#include <thread.h>
#include <draw.h>
#include <geometry.h>
#include "dat.h"
#include "fns.h"
/* DHX */
void
dhgenpg(ulong *p, ulong *g)
{
static ulong P = 97;
static ulong G = 71;
*p = P;
*g = G;
}
/*
* y = g^k mod p
*/
ulong
dhgenkey(ulong g, ulong k, ulong p)
{
ulong r, y;
y = 1;
while(k > 0){
r = k % 2;
if(r == 1)
y = y*g % p;
g = g*g % p;
k /= 2;
}
return y;
}
/* NetConn */
NetConn *
newnetconn(NCState s, Udphdr *u)
{
NetConn *nc;
nc = emalloc(sizeof(NetConn));
memset(nc, 0, sizeof(NetConn));
if(u != nil)
memmove(&nc->udp, u, Udphdrsize);
nc->state = s;
return nc;
}
void
delnetconn(NetConn *nc)
{
free(nc);
}
/* Frame */
Frame *
newframe(Udphdr *hdr, u8int type, u32int seq, u32int ack, u16int len, uchar *data)
{
Frame *f;
f = emalloc(sizeof(Frame)+len);
memset(f, 0, sizeof(Frame));
if(hdr != nil)
memmove(&f->udp, hdr, Udphdrsize);
f->id = ProtocolID;
f->type = type;
f->seq = seq;
f->ack = ack;
f->len = len;
if(data != nil)
memmove(f->data, data, f->len);
return f;
}
void
signframe(Frame *f, ulong key)
{
uchar k[sizeof(ulong)];
uchar h[MD5dlen];
uchar msg[MTU];
int n;
k[0] = key; k[1] = key>>8; k[2] = key>>16; k[3] = key>>24;
memset(f->sig, 0, MD5dlen);
n = pack(msg, sizeof msg, "f", f);
hmac_md5(msg, n, k, sizeof k, h, nil);
memmove(f->sig, h, MD5dlen);
}
int
verifyframe(Frame *f, ulong key)
{
uchar k[sizeof(ulong)];
uchar h0[MD5dlen], h1[MD5dlen];
uchar msg[MTU];
int n;
k[0] = key; k[1] = key>>8; k[2] = key>>16; k[3] = key>>24;
memmove(h0, f->sig, MD5dlen);
memset(f->sig, 0, MD5dlen);
n = pack(msg, sizeof msg, "f", f);
hmac_md5(msg, n, k, sizeof k, h1, nil);
return memcmp(h0, h1, MD5dlen) == 0;
}
void
delframe(Frame *f)
{
free(f);
}
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