- markus@cvs.openbsd.org 2003/07/02 14:51:16

[openssh.git] / channels.c

diff --git a/channels.c b/channels.c
index ce07db5c0225c13c6b8df0990be81a9000f82ca9..e5b2b8c515580a92c9b832cca66850430a3761ae 100644 (file)
--- a/channels.c
+++ b/channels.c
@@ -39,7 +39,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: channels.c,v 1.192 2003/07/02 12:56:34 markus Exp $");
+RCSID("$OpenBSD: channels.c,v 1.193 2003/07/02 14:51:16 markus Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -54,7 +54,7 @@ RCSID("$OpenBSD: channels.c,v 1.192 2003/07/02 12:56:34 markus Exp $");
 #include "key.h"
 #include "authfd.h"
 #include "pathnames.h"
-
+#include "bufaux.h"
 
 /* -- channel core */
 
@@ -941,6 +941,117 @@ channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
        return 1;
 }
 
+/* try to decode a socks5 header */
+#define SSH_SOCKS5_AUTHDONE    0x1000
+#define SSH_SOCKS5_NOAUTH      0x00
+#define SSH_SOCKS5_IPV4                0x01
+#define SSH_SOCKS5_DOMAIN      0x03
+#define SSH_SOCKS5_IPV6                0x04
+#define SSH_SOCKS5_CONNECT     0x01
+#define SSH_SOCKS5_SUCCESS     0x00
+
+static int
+channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
+{
+       struct {
+               u_int8_t version;
+               u_int8_t command;
+               u_int8_t reserved;
+               u_int8_t atyp;
+       } s5_req, s5_rsp;
+       u_int16_t dest_port;
+       u_char *p, dest_addr[255+1];
+       int i, have, found, nmethods, addrlen, af;
+
+       debug2("channel %d: decode socks5", c->self);
+       p = buffer_ptr(&c->input);
+       if (p[0] != 0x05)
+               return -1;
+       have = buffer_len(&c->input);
+       if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
+               /* format: ver | nmethods | methods */
+               if (have < 2) 
+                       return 0;
+               nmethods = p[1];
+               if (have < nmethods + 2)
+                       return 0;
+               /* look for method: "NO AUTHENTICATION REQUIRED" */
+               for (found = 0, i = 2 ; i < nmethods + 2; i++) {
+                       if (p[i] == SSH_SOCKS5_NOAUTH ) {
+                               found = 1;
+                               break;
+                       }
+               }
+               if (!found) {
+                       debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
+                           c->self);
+                       return -1;
+               }
+               buffer_consume(&c->input, nmethods + 2);
+               buffer_put_char(&c->output, 0x05);              /* version */
+               buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
+               FD_SET(c->sock, writeset);
+               c->flags |= SSH_SOCKS5_AUTHDONE;
+               debug2("channel %d: socks5 auth done", c->self);
+               return 0;                               /* need more */
+       }
+       debug2("channel %d: socks5 post auth", c->self);
+       if (have < sizeof(s5_req)+1)
+               return 0;                       /* need more */
+       memcpy((char *)&s5_req, p, sizeof(s5_req));
+       if (s5_req.version != 0x05 ||
+           s5_req.command != SSH_SOCKS5_CONNECT ||
+           s5_req.reserved != 0x00) {
+               debug("channel %d: only socks5 connect supported", c->self);
+               return -1;
+       }
+       switch(s5_req.atyp){
+       case SSH_SOCKS5_IPV4:
+               addrlen = 4;
+               af = AF_INET;
+               break;
+       case SSH_SOCKS5_DOMAIN:
+               addrlen = p[sizeof(s5_req)];
+               af = -1;
+               break;
+       case SSH_SOCKS5_IPV6:
+               addrlen = 16;
+               af = AF_INET6;
+               break;
+       default:
+               debug("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
+               return -1;
+       }
+       if (have < 4 + addrlen + 2)
+               return 0;
+       buffer_consume(&c->input, sizeof(s5_req));
+       if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
+               buffer_consume(&c->input, 1);    /* host string length */
+       buffer_get(&c->input, (char *)&dest_addr, addrlen);
+       buffer_get(&c->input, (char *)&dest_port, 2);
+       dest_addr[addrlen] = '\0';
+       if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
+               strlcpy(c->path, dest_addr, sizeof(c->path));
+       else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
+               return -1;
+       c->host_port = ntohs(dest_port);
+       
+       debug("channel %d: dynamic request: socks5 host %s port %u command %u",
+           c->self, c->path, c->host_port, s5_req.command);
+
+       s5_rsp.version = 0x05;
+       s5_rsp.command = SSH_SOCKS5_SUCCESS;
+       s5_rsp.reserved = 0;                    /* ignored */
+       s5_rsp.atyp = SSH_SOCKS5_IPV4;
+       ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
+       dest_port = 0;                          /* ignored */
+
+       buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
+       buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
+       buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
+       return 1;
+}
+
 /* dynamic port forwarding */
 static void
 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
@@ -953,7 +1064,7 @@ channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
        debug2("channel %d: pre_dynamic: have %d", c->self, have);
        /* buffer_dump(&c->input); */
        /* check if the fixed size part of the packet is in buffer. */
-       if (have < 4) {
+       if (have < 3) {
                /* need more */
                FD_SET(c->sock, readset);
                return;
@@ -964,6 +1075,9 @@ channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
        case 0x04:
                ret = channel_decode_socks4(c, readset, writeset);
                break;
+       case 0x05:
+               ret = channel_decode_socks5(c, readset, writeset);
+               break;
        default:
                ret = -1;
                break;