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- #include <u.h>
- #include <libc.h>
- #include <mp.h>
- #include <libsec.h>
- #include "SConn.h"
- extern int verbose;
- typedef struct ConnState {
- uchar secret[SHA1dlen];
- ulong seqno;
- RC4state rc4;
- } ConnState;
- typedef struct SS{
- int fd; // file descriptor for read/write of encrypted data
- int alg; // if nonzero, "alg sha rc4_128"
- ConnState in, out;
- } SS;
- static int
- SC_secret(SConn *conn, uchar *sigma, int direction)
- {
- SS *ss = (SS*)(conn->chan);
- int nsigma = conn->secretlen;
- if(direction != 0){
- hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->out.secret, nil);
- hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->in.secret, nil);
- }else{
- hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->out.secret, nil);
- hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->in.secret, nil);
- }
- setupRC4state(&ss->in.rc4, ss->in.secret, 16); // restrict to 128 bits
- setupRC4state(&ss->out.rc4, ss->out.secret, 16);
- ss->alg = 1;
- return 0;
- }
- static void
- hash(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
- {
- DigestState sha;
- uchar seq[4];
- seq[0] = seqno>>24;
- seq[1] = seqno>>16;
- seq[2] = seqno>>8;
- seq[3] = seqno;
- memset(&sha, 0, sizeof sha);
- sha1(secret, SHA1dlen, nil, &sha);
- sha1(data, len, nil, &sha);
- sha1(seq, 4, d, &sha);
- }
- static int
- verify(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
- {
- DigestState sha;
- uchar seq[4];
- uchar digest[SHA1dlen];
- seq[0] = seqno>>24;
- seq[1] = seqno>>16;
- seq[2] = seqno>>8;
- seq[3] = seqno;
- memset(&sha, 0, sizeof sha);
- sha1(secret, SHA1dlen, nil, &sha);
- sha1(data, len, nil, &sha);
- sha1(seq, 4, digest, &sha);
- return memcmp(d, digest, SHA1dlen);
- }
- static int
- SC_read(SConn *conn, uchar *buf, int n)
- {
- SS *ss = (SS*)(conn->chan);
- uchar count[2], digest[SHA1dlen];
- int len, nr;
- if(read(ss->fd, count, 2) != 2 || (count[0]&0x80) == 0){
- snprint((char*)buf,n,"!SC_read invalid count");
- return -1;
- }
- len = (count[0]&0x7f)<<8 | count[1]; // SSL-style count; no pad
- if(ss->alg){
- len -= SHA1dlen;
- if(len <= 0 || readn(ss->fd, digest, SHA1dlen) != SHA1dlen){
- snprint((char*)buf,n,"!SC_read missing sha1");
- return -1;
- }
- if(len > n || readn(ss->fd, buf, len) != len){
- snprint((char*)buf,n,"!SC_read missing data");
- return -1;
- }
- rc4(&ss->in.rc4, digest, SHA1dlen);
- rc4(&ss->in.rc4, buf, len);
- if(verify(ss->in.secret, buf, len, ss->in.seqno, digest) != 0){
- snprint((char*)buf,n,"!SC_read integrity check failed");
- return -1;
- }
- }else{
- if(len <= 0 || len > n){
- snprint((char*)buf,n,"!SC_read implausible record length");
- return -1;
- }
- if( (nr = readn(ss->fd, buf, len)) != len){
- snprint((char*)buf,n,"!SC_read expected %d bytes, but got %d", len, nr);
- return -1;
- }
- }
- ss->in.seqno++;
- return len;
- }
- static int
- SC_write(SConn *conn, uchar *buf, int n)
- {
- SS *ss = (SS*)(conn->chan);
- uchar count[2], digest[SHA1dlen], enc[Maxmsg+1];
- int len;
- if(n <= 0 || n > Maxmsg+1){
- werrstr("!SC_write invalid n %d", n);
- return -1;
- }
- len = n;
- if(ss->alg)
- len += SHA1dlen;
- count[0] = 0x80 | len>>8;
- count[1] = len;
- if(write(ss->fd, count, 2) != 2){
- werrstr("!SC_write invalid count");
- return -1;
- }
- if(ss->alg){
- hash(ss->out.secret, buf, n, ss->out.seqno, digest);
- rc4(&ss->out.rc4, digest, SHA1dlen);
- memcpy(enc, buf, n);
- rc4(&ss->out.rc4, enc, n);
- if(write(ss->fd, digest, SHA1dlen) != SHA1dlen ||
- write(ss->fd, enc, n) != n){
- werrstr("!SC_write error on send");
- return -1;
- }
- }else{
- if(write(ss->fd, buf, n) != n){
- werrstr("!SC_write error on send");
- return -1;
- }
- }
- ss->out.seqno++;
- return n;
- }
- static void
- SC_free(SConn *conn)
- {
- SS *ss = (SS*)(conn->chan);
- close(ss->fd);
- free(ss);
- free(conn);
- }
- SConn*
- newSConn(int fd)
- {
- SS *ss;
- SConn *conn;
- if(fd < 0)
- return nil;
- ss = (SS*)emalloc(sizeof(*ss));
- conn = (SConn*)emalloc(sizeof(*conn));
- ss->fd = fd;
- ss->alg = 0;
- conn->chan = (void*)ss;
- conn->secretlen = SHA1dlen;
- conn->free = SC_free;
- conn->secret = SC_secret;
- conn->read = SC_read;
- conn->write = SC_write;
- return conn;
- }
- void
- writerr(SConn *conn, char *s)
- {
- char buf[Maxmsg];
- snprint(buf, Maxmsg, "!%s", s);
- conn->write(conn, (uchar*)buf, strlen(buf));
- }
- int
- readstr(SConn *conn, char *s)
- {
- int n;
- n = conn->read(conn, (uchar*)s, Maxmsg);
- if(n >= 0){
- s[n] = 0;
- if(s[0] == '!'){
- memmove(s, s+1, n);
- n = -1;
- }
- }else{
- strcpy(s, "read error");
- }
- return n;
- }
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