More preparatory work: remove the <windows.h> include from lots of
[u/mdw/putty] / proxy.c
diff --git a/proxy.c b/proxy.c
index e8f0fdc..0760e7e 100644 (file)
--- a/proxy.c
+++ b/proxy.c
@@ -5,7 +5,9 @@
  * code and the higher level backend.
  */
 
-#include <windows.h>
+#include <assert.h>
+#include <ctype.h>
+#include <string.h>
 
 #define DEFINE_PLUG_METHOD_MACROS
 #include "putty.h"
@@ -20,43 +22,50 @@ void proxy_activate (Proxy_Socket p)
 {
     void *data;
     int len;
-
+    long output_before, output_after;
+    
     p->state = PROXY_STATE_ACTIVE;
 
-    /* let's try to keep extra receive events from coming through */
+    /* we want to ignore new receive events until we have sent
+     * all of our buffered receive data.
+     */
     sk_set_frozen(p->sub_socket, 1);
 
+    /* how many bytes of output have we buffered? */
+    output_before = bufchain_size(&p->pending_oob_output_data) +
+       bufchain_size(&p->pending_output_data);
+    /* and keep track of how many bytes do not get sent. */
+    output_after = 0;
+    
     /* send buffered OOB writes */
     while (bufchain_size(&p->pending_oob_output_data) > 0) {
        bufchain_prefix(&p->pending_oob_output_data, &data, &len);
-       sk_write_oob(p->sub_socket, data, len);
+       output_after += sk_write_oob(p->sub_socket, data, len);
        bufchain_consume(&p->pending_oob_output_data, len);
     }
-    bufchain_clear(&p->pending_oob_output_data);
 
     /* send buffered normal writes */
     while (bufchain_size(&p->pending_output_data) > 0) {
        bufchain_prefix(&p->pending_output_data, &data, &len);
-       sk_write(p->sub_socket, data, len);
+       output_after += sk_write(p->sub_socket, data, len);
        bufchain_consume(&p->pending_output_data, len);
     }
-    bufchain_clear(&p->pending_output_data);
+
+    /* if we managed to send any data, let the higher levels know. */
+    if (output_after < output_before)
+       plug_sent(p->plug, output_after);
 
     /* if we were asked to flush the output during
      * the proxy negotiation process, do so now.
      */
     if (p->pending_flush) sk_flush(p->sub_socket);
 
-    /* forward buffered recv data to the backend */
-    while (bufchain_size(&p->pending_input_data) > 0) {
-       bufchain_prefix(&p->pending_input_data, &data, &len);
-       plug_receive(p->plug, 0, data, len);
-       bufchain_consume(&p->pending_input_data, len);
-    }
-    bufchain_clear(&p->pending_input_data);
-
-    /* now set the underlying socket to whatever freeze state they wanted */
-    sk_set_frozen(p->sub_socket, p->freeze);
+    /* if the backend wanted the socket unfrozen, try to unfreeze.
+     * our set_frozen handler will flush buffered receive data before
+     * unfreezing the actual underlying socket.
+     */
+    if (!p->freeze)
+       sk_set_frozen((Socket)p, 0);
 }
 
 /* basic proxy socket functions */
@@ -133,6 +142,30 @@ static void sk_proxy_set_frozen (Socket s, int is_frozen)
        ps->freeze = is_frozen;
        return;
     }
+    
+    /* handle any remaining buffered recv data first */
+    if (bufchain_size(&ps->pending_input_data) > 0) {
+       ps->freeze = is_frozen;
+
+       /* loop while we still have buffered data, and while we are
+        * unfrozen. the plug_receive call in the loop could result 
+        * in a call back into this function refreezing the socket, 
+        * so we have to check each time.
+        */
+        while (!ps->freeze && bufchain_size(&ps->pending_input_data) > 0) {
+           void *data;
+           int len;
+           bufchain_prefix(&ps->pending_input_data, &data, &len);
+           plug_receive(ps->plug, 0, data, len);
+           bufchain_consume(&ps->pending_input_data, len);
+       }
+
+       /* if we're still frozen, we'll have to wait for another
+        * call from the backend to finish unbuffering the data.
+        */
+       if (ps->freeze) return;
+    }
+    
     sk_set_frozen(ps->sub_socket, is_frozen);
 }
 
@@ -279,7 +312,7 @@ Socket new_connection(SockAddr addr, char *hostname,
                      int port, int privport,
                      int oobinline, int nodelay, Plug plug)
 {
-    static struct socket_function_table socket_fn_table = {
+    static const struct socket_function_table socket_fn_table = {
        sk_proxy_plug,
        sk_proxy_close,
        sk_proxy_write,
@@ -291,7 +324,7 @@ Socket new_connection(SockAddr addr, char *hostname,
        sk_proxy_socket_error
     };
 
-    static struct plug_function_table plug_fn_table = {
+    static const struct plug_function_table plug_fn_table = {
        plug_proxy_closing,
        plug_proxy_receive,
        plug_proxy_sent,
@@ -312,21 +345,29 @@ Socket new_connection(SockAddr addr, char *hostname,
        ret->remote_addr = addr;
        ret->remote_port = port;
 
+       ret->error = NULL;
+       ret->pending_flush = 0;
+       ret->freeze = 0;
+
        bufchain_init(&ret->pending_input_data);
        bufchain_init(&ret->pending_output_data);
        bufchain_init(&ret->pending_oob_output_data);
 
        ret->sub_socket = NULL;
        ret->state = PROXY_STATE_NEW;
-
+       ret->negotiate = NULL;
+       
        if (cfg.proxy_type == PROXY_HTTP) {
            ret->negotiate = proxy_http_negotiate;
        } else if (cfg.proxy_type == PROXY_SOCKS) {
-           ret->negotiate = proxy_socks_negotiate;
+           if (cfg.proxy_socks_version == 4)
+               ret->negotiate = proxy_socks4_negotiate;
+           else
+               ret->negotiate = proxy_socks5_negotiate;
        } else if (cfg.proxy_type == PROXY_TELNET) {
            ret->negotiate = proxy_telnet_negotiate;
        } else {
-           ret->error = "Network error: Unknown proxy method";
+           ret->error = "Proxy error: Unknown proxy method";
            return (Socket) ret;
        }
 
@@ -422,12 +463,27 @@ int proxy_http_negotiate (Proxy_Socket p, int change)
 
        sk_getaddr(p->remote_addr, dest, 64);
 
-       sprintf(buf, "CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n\r\n",
+       sprintf(buf, "CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n",
                dest, p->remote_port, dest, p->remote_port);
        sk_write(p->sub_socket, buf, strlen(buf));
 
-       p->state = 1;
+       if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
+           char buf[sizeof(cfg.proxy_username)+sizeof(cfg.proxy_password)];
+           char buf2[sizeof(buf)*4/3 + 100];
+           int i, j, len;
+           sprintf(buf, "%s:%s", cfg.proxy_username, cfg.proxy_password);
+           len = strlen(buf);
+           sprintf(buf2, "Proxy-Authorization: basic ");
+           for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
+               base64_encode_atom(buf+i, (len-i > 3 ? 3 : len-i), buf2+j);
+           strcpy(buf2+j, "\r\n");
+           sk_write(p->sub_socket, buf2, strlen(buf2));
+       }
+
+       sprintf(buf, "\r\n");
+       sk_write(p->sub_socket, buf, strlen(buf));
 
+       p->state = 1;
        return 0;
     }
 
@@ -466,7 +522,7 @@ int proxy_http_negotiate (Proxy_Socket p, int change)
         * we'll need to parse, process, and respond to appropriately.
         */
 
-       void *data;
+       char *data, *datap;
        int len;
        int eol;
 
@@ -475,27 +531,45 @@ int proxy_http_negotiate (Proxy_Socket p, int change)
            int min_ver, maj_ver, status;
 
            /* get the status line */
-           bufchain_prefix(&p->pending_input_data, &data, &len);
+           len = bufchain_size(&p->pending_input_data);
+           assert(len > 0);           /* or we wouldn't be here */
+           data = smalloc(len);
+           bufchain_fetch(&p->pending_input_data, data, len);
+
            eol = get_line_end(data, len);
-           if (eol < 0) return 1;
+           if (eol < 0) {
+               sfree(data);
+               return 1;
+           }
 
-           sscanf((char *)data, "HTTP/%i.%i %i", &maj_ver, &min_ver, &status);
+           status = -1;
+           /* We can't rely on whether the %n incremented the sscanf return */
+           if (sscanf((char *)data, "HTTP/%i.%i %n",
+                      &maj_ver, &min_ver, &status) < 2 || status == -1) {
+               plug_closing(p->plug, "Proxy error: HTTP response was absent",
+                            PROXY_ERROR_GENERAL, 0);
+               sfree(data);
+               return 1;
+           }
 
            /* remove the status line from the input buffer. */
            bufchain_consume(&p->pending_input_data, eol);
-
-           /* TODO: we need to support Proxy-Auth headers */
-
-           if (status < 200 || status > 299) {
+           if (data[status] != '2') {
                /* error */
-               /* TODO: return a more specific error message,
-                * TODO: based on the status code.
-                */
-               plug_closing(p->plug, "Network error: Error while communicating with proxy",
-                           PROXY_ERROR_GENERAL, 0);
+               char buf[1024];
+               data[eol] = '\0';
+               while (eol > status &&
+                      (data[eol-1] == '\r' || data[eol-1] == '\n'))
+                   data[--eol] = '\0';
+               sprintf(buf, "Proxy error: %.900s",
+                       data+status);
+               plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
+               sfree(data);
                return 1;
            }
 
+           sfree(data);
+
            p->state = 2;
        }
 
@@ -505,16 +579,22 @@ int proxy_http_negotiate (Proxy_Socket p, int change)
             * header of length 2, (ie. just "\r\n")
             */
 
-           bufchain_prefix(&p->pending_input_data, &data, &len);
-           eol = get_line_end(data, len);
+           len = bufchain_size(&p->pending_input_data);
+           assert(len > 0);           /* or we wouldn't be here */
+           data = smalloc(len);
+           datap = data;
+           bufchain_fetch(&p->pending_input_data, data, len);
+
+           eol = get_line_end(datap, len);
+           if (eol < 0) {
+               sfree(data);
+               return 1;
+           }
            while (eol > 2)
            {
-               /* TODO: Proxy-Auth stuff. in some cases, we will
-                * TODO: need to extract information from headers.
-                */
                bufchain_consume(&p->pending_input_data, eol);
-               bufchain_prefix(&p->pending_input_data, &data, &len);
-               eol = get_line_end(data, len);
+               datap += eol;
+               eol = get_line_end(datap, len);
            }
 
            if (eol == 2) {
@@ -523,26 +603,484 @@ int proxy_http_negotiate (Proxy_Socket p, int change)
                proxy_activate(p);
                /* proxy activate will have dealt with
                 * whatever is left of the buffer */
+               sfree(data);
                return 1;
            }
 
+           sfree(data);
            return 1;
        }
     }
 
-    plug_closing(p->plug, "Network error: Unexpected proxy error",
+    plug_closing(p->plug, "Proxy error: unexpected proxy error",
                 PROXY_ERROR_UNEXPECTED, 0);
-    return 0;
+    return 1;
 }
 
 /* ----------------------------------------------------------------------
- * SOCKS proxy type (as yet unimplemented).
+ * SOCKS proxy type.
  */
 
-int proxy_socks_negotiate (Proxy_Socket p, int change)
+/* SOCKS version 4 */
+int proxy_socks4_negotiate (Proxy_Socket p, int change)
 {
-    p->error = "Network error: SOCKS proxy implementation is incomplete";
-    return 0;
+    if (p->state == PROXY_CHANGE_NEW) {
+
+       /* request format:
+        *  version number (1 byte) = 4
+        *  command code (1 byte)
+        *    1 = CONNECT
+        *    2 = BIND
+        *  dest. port (2 bytes) [network order]
+        *  dest. address (4 bytes)
+        *  user ID (variable length, null terminated string)
+        */
+
+       int length;
+       char * command;
+
+       if (sk_addrtype(p->remote_addr) != ADDRTYPE_IPV4) {
+           plug_closing(p->plug, "Proxy error: SOCKS version 4 does"
+                        " not support IPv6", PROXY_ERROR_GENERAL, 0);
+           return 1;
+       }
+
+       length = strlen(cfg.proxy_username) + 9;
+       command = (char*) smalloc(length);
+       strcpy(command + 8, cfg.proxy_username);
+
+       command[0] = 4; /* version 4 */
+       command[1] = 1; /* CONNECT command */
+
+       /* port */
+       command[2] = (char) (p->remote_port >> 8) & 0xff;
+       command[3] = (char) p->remote_port & 0xff;
+
+       /* address */
+       sk_addrcopy(p->remote_addr, command + 4);
+
+       sk_write(p->sub_socket, command, length);
+       sfree(command);
+
+       p->state = 1;
+       return 0;
+    }
+
+    if (change == PROXY_CHANGE_CLOSING) {
+       /* if our proxy negotiation process involves closing and opening
+        * new sockets, then we would want to intercept this closing
+        * callback when we were expecting it. if we aren't anticipating
+        * a socket close, then some error must have occurred. we'll
+        * just pass those errors up to the backend.
+        */
+       return plug_closing(p->plug, p->closing_error_msg,
+                           p->closing_error_code,
+                           p->closing_calling_back);
+    }
+
+    if (change == PROXY_CHANGE_SENT) {
+       /* some (or all) of what we wrote to the proxy was sent.
+        * we don't do anything new, however, until we receive the
+        * proxy's response. we might want to set a timer so we can
+        * timeout the proxy negotiation after a while...
+        */
+       return 0;
+    }
+
+    if (change == PROXY_CHANGE_ACCEPTING) {
+       /* we should _never_ see this, as we are using our socket to
+        * connect to a proxy, not accepting inbound connections.
+        * what should we do? close the socket with an appropriate
+        * error message?
+        */
+       return plug_accepting(p->plug, p->accepting_sock);
+    }
+
+    if (change == PROXY_CHANGE_RECEIVE) {
+       /* we have received data from the underlying socket, which
+        * we'll need to parse, process, and respond to appropriately.
+        */
+
+       if (p->state == 1) {
+           /* response format:
+            *  version number (1 byte) = 4
+            *  reply code (1 byte)
+            *    90 = request granted
+            *    91 = request rejected or failed
+            *    92 = request rejected due to lack of IDENTD on client
+            *    93 = request rejected due to difference in user ID 
+            *         (what we sent vs. what IDENTD said)
+            *  dest. port (2 bytes)
+            *  dest. address (4 bytes)
+            */
+
+           char data[8];
+
+           if (bufchain_size(&p->pending_input_data) < 8)
+               return 1;              /* not got anything yet */
+           
+           /* get the response */
+           bufchain_fetch(&p->pending_input_data, data, 8);
+
+           if (data[0] != 0) {
+               plug_closing(p->plug, "Proxy error: SOCKS proxy responded with "
+                                     "unexpected reply code version",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+
+           if (data[1] != 90) {
+
+               switch (data[1]) {
+                 case 92:
+                   plug_closing(p->plug, "Proxy error: SOCKS server wanted IDENTD on client",
+                                PROXY_ERROR_GENERAL, 0);
+                   break;
+                 case 93:
+                   plug_closing(p->plug, "Proxy error: Username and IDENTD on client don't agree",
+                                PROXY_ERROR_GENERAL, 0);
+                   break;
+                 case 91:
+                 default:
+                   plug_closing(p->plug, "Proxy error: Error while communicating with proxy",
+                                PROXY_ERROR_GENERAL, 0);
+                   break;
+               }
+
+               return 1;
+           }
+           bufchain_consume(&p->pending_input_data, 8);
+
+           /* we're done */
+           proxy_activate(p);
+           /* proxy activate will have dealt with
+            * whatever is left of the buffer */
+           return 1;
+       }
+    }
+
+    plug_closing(p->plug, "Proxy error: unexpected proxy error",
+                PROXY_ERROR_UNEXPECTED, 0);
+    return 1;
+}
+
+/* SOCKS version 5 */
+int proxy_socks5_negotiate (Proxy_Socket p, int change)
+{
+    if (p->state == PROXY_CHANGE_NEW) {
+
+       /* initial command:
+        *  version number (1 byte) = 5
+        *  number of available authentication methods (1 byte)
+        *  available authentication methods (1 byte * previous value)
+        *    authentication methods:
+        *     0x00 = no authentication
+        *     0x01 = GSSAPI
+        *     0x02 = username/password
+        *     0x03 = CHAP
+        */
+
+       char command[4];
+       int len;
+
+       command[0] = 5; /* version 5 */
+       if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
+           command[1] = 2;            /* two methods supported: */
+           command[2] = 0x00;         /* no authentication */
+           command[3] = 0x02;         /* username/password */
+           len = 4;
+       } else {
+           command[1] = 1;            /* one methods supported: */
+           command[2] = 0x00;         /* no authentication */
+           len = 3;
+       }
+
+       sk_write(p->sub_socket, command, len);
+
+       p->state = 1;
+       return 0;
+    }
+
+    if (change == PROXY_CHANGE_CLOSING) {
+       /* if our proxy negotiation process involves closing and opening
+        * new sockets, then we would want to intercept this closing
+        * callback when we were expecting it. if we aren't anticipating
+        * a socket close, then some error must have occurred. we'll
+        * just pass those errors up to the backend.
+        */
+       return plug_closing(p->plug, p->closing_error_msg,
+                           p->closing_error_code,
+                           p->closing_calling_back);
+    }
+
+    if (change == PROXY_CHANGE_SENT) {
+       /* some (or all) of what we wrote to the proxy was sent.
+        * we don't do anything new, however, until we receive the
+        * proxy's response. we might want to set a timer so we can
+        * timeout the proxy negotiation after a while...
+        */
+       return 0;
+    }
+
+    if (change == PROXY_CHANGE_ACCEPTING) {
+       /* we should _never_ see this, as we are using our socket to
+        * connect to a proxy, not accepting inbound connections.
+        * what should we do? close the socket with an appropriate
+        * error message?
+        */
+       return plug_accepting(p->plug, p->accepting_sock);
+    }
+
+    if (change == PROXY_CHANGE_RECEIVE) {
+       /* we have received data from the underlying socket, which
+        * we'll need to parse, process, and respond to appropriately.
+        */
+
+       if (p->state == 1) {
+
+           /* initial response:
+            *  version number (1 byte) = 5
+            *  authentication method (1 byte)
+            *    authentication methods:
+            *     0x00 = no authentication
+            *     0x01 = GSSAPI
+            *     0x02 = username/password 
+            *     0x03 = CHAP
+            *     0xff = no acceptable methods
+            */
+           char data[2];
+
+           if (bufchain_size(&p->pending_input_data) < 2)
+               return 1;              /* not got anything yet */
+
+           /* get the response */
+           bufchain_fetch(&p->pending_input_data, data, 2);
+
+           if (data[0] != 5) {
+               plug_closing(p->plug, "Proxy error: SOCKS proxy returned unexpected version",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+
+           if (data[1] == 0x00) p->state = 2; /* no authentication needed */
+           else if (data[1] == 0x01) p->state = 4; /* GSSAPI authentication */
+           else if (data[1] == 0x02) p->state = 5; /* username/password authentication */
+           else if (data[1] == 0x03) p->state = 6; /* CHAP authentication */
+           else {
+               plug_closing(p->plug, "Proxy error: SOCKS proxy did not accept our authentication",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+           bufchain_consume(&p->pending_input_data, 2);
+       }
+
+       if (p->state == 7) {
+
+           /* password authentication reply format:
+            *  version number (1 bytes) = 1
+            *  reply code (1 byte)
+            *    0 = succeeded
+            *    >0 = failed
+            */
+           char data[2];
+
+           if (bufchain_size(&p->pending_input_data) < 2)
+               return 1;              /* not got anything yet */
+
+           /* get the response */
+           bufchain_fetch(&p->pending_input_data, data, 2);
+
+           if (data[0] != 1) {
+               plug_closing(p->plug, "Proxy error: SOCKS password "
+                            "subnegotiation contained wrong version number",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+
+           if (data[1] != 0) {
+
+               plug_closing(p->plug, "Proxy error: SOCKS proxy refused"
+                            " password authentication",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+
+           bufchain_consume(&p->pending_input_data, 2);
+           p->state = 2;              /* now proceed as authenticated */
+       }
+
+       if (p->state == 2) {
+
+           /* request format:
+            *  version number (1 byte) = 5
+            *  command code (1 byte)
+            *    1 = CONNECT
+            *    2 = BIND
+            *    3 = UDP ASSOCIATE
+            *  reserved (1 byte) = 0x00
+            *  address type (1 byte)
+            *    1 = IPv4
+            *    3 = domainname (first byte has length, no terminating null)
+            *    4 = IPv6
+            *  dest. address (variable)
+            *  dest. port (2 bytes) [network order]
+            */
+
+           char command[22];
+           int len;
+
+           if (sk_addrtype(p->remote_addr) == ADDRTYPE_IPV6) {
+               len = 10;
+               command[3] = 1; /* IPv4 */
+           } else {
+               len = 22;
+               command[3] = 4; /* IPv6 */
+           }
+
+           command[0] = 5; /* version 5 */
+           command[1] = 1; /* CONNECT command */
+           command[2] = 0x00;
+
+           /* address */
+           sk_addrcopy(p->remote_addr, command+4);
+
+           /* port */
+           command[len-2] = (char) (p->remote_port >> 8) & 0xff;
+           command[len-1] = (char) p->remote_port & 0xff;
+
+           sk_write(p->sub_socket, command, len);
+
+           p->state = 3;
+           return 1;
+       }
+
+       if (p->state == 3) {
+
+           /* reply format:
+            *  version number (1 bytes) = 5
+            *  reply code (1 byte)
+            *    0 = succeeded
+            *    1 = general SOCKS server failure
+            *    2 = connection not allowed by ruleset
+            *    3 = network unreachable
+            *    4 = host unreachable
+            *    5 = connection refused
+            *    6 = TTL expired
+            *    7 = command not supported
+            *    8 = address type not supported
+            * reserved (1 byte) = x00
+            * address type (1 byte)
+            *    1 = IPv4
+            *    3 = domainname (first byte has length, no terminating null)
+            *    4 = IPv6
+            * server bound address (variable)
+            * server bound port (2 bytes) [network order]
+            */
+           char data[5];
+           int len;
+
+           /* First 5 bytes of packet are enough to tell its length. */ 
+           if (bufchain_size(&p->pending_input_data) < 5)
+               return 1;              /* not got anything yet */
+
+           /* get the response */
+           bufchain_fetch(&p->pending_input_data, data, 5);
+
+           if (data[0] != 5) {
+               plug_closing(p->plug, "Proxy error: SOCKS proxy returned wrong version number",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+
+           if (data[1] != 0) {
+               char buf[256];
+
+               strcpy(buf, "Proxy error: ");
+
+               switch (data[1]) {
+                 case 1: strcat(buf, "General SOCKS server failure"); break;
+                 case 2: strcat(buf, "Connection not allowed by ruleset"); break;
+                 case 3: strcat(buf, "Network unreachable"); break;
+                 case 4: strcat(buf, "Host unreachable"); break;
+                 case 5: strcat(buf, "Connection refused"); break;
+                 case 6: strcat(buf, "TTL expired"); break;
+                 case 7: strcat(buf, "Command not supported"); break;
+                 case 8: strcat(buf, "Address type not supported"); break;
+                 default: sprintf(buf+strlen(buf),
+                                  "Unrecognised SOCKS error code %d",
+                                  data[1]);
+                   break;
+               }
+               plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
+
+               return 1;
+           }
+
+           /*
+            * Eat the rest of the reply packet.
+            */
+           len = 6;                   /* first 4 bytes, last 2 */
+           switch (data[3]) {
+             case 1: len += 4; break; /* IPv4 address */
+             case 4: len += 16; break;/* IPv6 address */
+             case 3: len += (unsigned char)data[4]; break; /* domain name */
+             default:
+               plug_closing(p->plug, "Proxy error: SOCKS proxy returned "
+                            "unrecognised address format",
+                            PROXY_ERROR_GENERAL, 0);
+               return 1;
+           }
+           if (bufchain_size(&p->pending_input_data) < len)
+               return 1;              /* not got whole reply yet */
+           bufchain_consume(&p->pending_input_data, len);
+
+           /* we're done */
+           proxy_activate(p);
+           return 1;
+       }
+
+       if (p->state == 4) {
+           /* TODO: Handle GSSAPI authentication */
+           plug_closing(p->plug, "Proxy error: We don't support GSSAPI authentication",
+                        PROXY_ERROR_GENERAL, 0);
+           return 1;
+       }
+
+       if (p->state == 5) {
+           if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
+               char userpwbuf[514];
+               int ulen, plen;
+               ulen = strlen(cfg.proxy_username);
+               if (ulen > 255) ulen = 255; if (ulen < 1) ulen = 1;
+               plen = strlen(cfg.proxy_password);
+               if (plen > 255) plen = 255; if (plen < 1) plen = 1;
+               userpwbuf[0] = 1;      /* version number of subnegotiation */
+               userpwbuf[1] = ulen;
+               memcpy(userpwbuf+2, cfg.proxy_username, ulen);
+               userpwbuf[ulen+2] = plen;
+               memcpy(userpwbuf+ulen+3, cfg.proxy_password, plen);
+               sk_write(p->sub_socket, userpwbuf, ulen + plen + 3);
+               p->state = 7;
+           } else 
+               plug_closing(p->plug, "Proxy error: Server chose "
+                            "username/password authentication but we "
+                            "didn't offer it!",
+                        PROXY_ERROR_GENERAL, 0);
+           return 1;
+       }
+
+       if (p->state == 6) {
+           /* TODO: Handle CHAP authentication */
+           plug_closing(p->plug, "Proxy error: We don't support CHAP authentication",
+                        PROXY_ERROR_GENERAL, 0);
+           return 1;
+       }
+
+    }
+
+    plug_closing(p->plug, "Proxy error: Unexpected proxy error",
+                PROXY_ERROR_UNEXPECTED, 0);
+    return 1;
 }
 
 /* ----------------------------------------------------------------------
@@ -561,7 +1099,7 @@ int proxy_telnet_negotiate (Proxy_Socket p, int change)
        int so = 0, eo = 0;
 
        /* we need to escape \\, \%, \r, \n, \t, \x??, \0???, 
-        * %%, %host, and %port 
+        * %%, %host, %port, %user, and %pass
         */
 
        while (cfg.proxy_telnet_command[eo] != 0) {
@@ -669,27 +1207,40 @@ int proxy_telnet_negotiate (Proxy_Socket p, int change)
                }
            } else {
 
-               /* % escape. we recognize %%, %host, %port. anything else,
-                * we just send unescaped (including the %). */
+               /* % escape. we recognize %%, %host, %port, %user, %pass. 
+                * anything else, we just send unescaped (including the %). 
+                */
 
                if (cfg.proxy_telnet_command[eo] == '%') {
                    sk_write(p->sub_socket, "%", 1);
                    eo++;
-               } 
+               }
                else if (strnicmp(cfg.proxy_telnet_command + eo,
                                  "host", 4) == 0) {
                    char dest[64];
                    sk_getaddr(p->remote_addr, dest, 64);
                    sk_write(p->sub_socket, dest, strlen(dest));
                    eo += 4;
-               } 
+               }
                else if (strnicmp(cfg.proxy_telnet_command + eo,
                                  "port", 4) == 0) {
                    char port[8];
                    sprintf(port, "%i", p->remote_port);
                    sk_write(p->sub_socket, port, strlen(port));
                    eo += 4;
-               } 
+               }
+               else if (strnicmp(cfg.proxy_telnet_command + eo,
+                                 "user", 4) == 0) {
+                   sk_write(p->sub_socket, cfg.proxy_username, 
+                       strlen(cfg.proxy_username));
+                   eo += 4;
+               }
+               else if (strnicmp(cfg.proxy_telnet_command + eo,
+                                 "pass", 4) == 0) {
+                   sk_write(p->sub_socket, cfg.proxy_password, 
+                       strlen(cfg.proxy_password));
+                   eo += 4;
+               }
                else {
                    /* we don't escape this, so send the % now, and
                     * don't advance eo, so that we'll consider the
@@ -709,7 +1260,6 @@ int proxy_telnet_negotiate (Proxy_Socket p, int change)
        }
 
        p->state = 1;
-
        return 0;
     }
 
@@ -755,7 +1305,7 @@ int proxy_telnet_negotiate (Proxy_Socket p, int change)
        return 1;
     }
 
-    plug_closing(p->plug, "Network error: Unexpected proxy error",
+    plug_closing(p->plug, "Proxy error: Unexpected proxy error",
                 PROXY_ERROR_UNEXPECTED, 0);
-    return 0;
+    return 1;
 }