Re: vncv(1): support for RFB 3.8

["Iruatã Souza" <iru.muzgo@gmail.com>]

Hi,

Did anyone try this? kvik?

On Mon, Jun 22, 2020 at 7:37 PM Iruatã Souza <iru.muzgo@gmail.com> wrote:
>
> Hi,
>
> The following patch adds support for RFB 3.8 in vncv(1).
> It has been tested by connecting to a screen shared by gnome3 on
> linux. Please let me know if it introduces any regressions.
>
> diff -r 19baa5600a90 sys/man/1/vnc
> --- a/sys/man/1/vnc    Mon Apr 06 01:31:35 2020 +0200
> +++ b/sys/man/1/vnc    Mon Jun 22 19:25:55 2020 +0200
> @@ -204,6 +204,3 @@
>  .I Vncv
>  does no verification of the TLS certificate presented
>  by the server.
> -.PP
> -.I Vncv
> -supports only version 3.3 of the RFB protocol.
> diff -r 19baa5600a90 sys/src/cmd/vnc/auth.c
> --- a/sys/src/cmd/vnc/auth.c    Mon Apr 06 01:31:35 2020 +0200
> +++ b/sys/src/cmd/vnc/auth.c    Mon Jun 22 19:25:55 2020 +0200
> @@ -9,14 +9,16 @@
>      VerLen    = 12
>  };
>
> -static char version[VerLen+1] = "RFB 003.003\n";
> +static char version33[VerLen+1] = "RFB 003.003\n";
> +static char version38[VerLen+1] = "RFB 003.008\n";
> +static int srvversion;
>
>  int
>  vncsrvhandshake(Vnc *v)
>  {
>      char msg[VerLen+1];
>
> -    strecpy(msg, msg+sizeof msg, version);
> +    strecpy(msg, msg+sizeof msg, version33);
>      if(verbose)
>          fprint(2, "server version: %s\n", msg);
>      vncwrbytes(v, msg, VerLen);
> @@ -35,18 +37,51 @@
>
>      msg[VerLen] = 0;
>      vncrdbytes(v, msg, VerLen);
> -    if(strncmp(msg, "RFB ", 4) != 0){
> +    if(strncmp(msg, "RFB 003.", 8) != 0) {
>          werrstr("bad rfb version \"%s\"", msg);
>          return -1;
>      }
> +    if(strncmp(msg, "RFB 003.008\n", VerLen) == 0)
> +        srvversion = 38;
> +    else
> +        srvversion = 33;
> +
>      if(verbose)
>          fprint(2, "server version: %s\n", msg);
> -    strcpy(msg, version);
> +    strcpy(msg, version38);
>      vncwrbytes(v, msg, VerLen);
>      vncflush(v);
>      return 0;
>  }
>
> +ulong
> +sectype38(Vnc *v)
> +{
> +    ulong auth, type;
> +    int i, ntypes;
> +
> +    ntypes = vncrdchar(v);
> +    if (ntypes == 0) {
> +        werrstr("no security types from server");
> +        return AFailed;
> +    }
> +
> +    /* choose the "most secure" security type */
> +    auth = AFailed;
> +    for (i = 0; i < ntypes; i++) {
> +        type = vncrdchar(v);
> +        if(verbose){
> +            fprint(2, "auth type %s\n",
> +                type == AFailed ? "Invalid" :
> +                type == ANoAuth ? "None" :
> +                type == AVncAuth ? "VNC" : "Unknown");
> +        }
> +        if(type > auth)
> +            auth = type;
> +    }
> +    return auth;
> +}
> +
>  int
>  vncauth(Vnc *v, char *keypattern)
>  {
> @@ -56,7 +91,9 @@
>
>      if(keypattern == nil)
>          keypattern = "";
> -    auth = vncrdlong(v);
> +
> +    auth = srvversion == 38 ? sectype38(v) : vncrdlong(v);
> +
>      switch(auth){
>      default:
>          werrstr("unknown auth type 0x%lux", auth);
> @@ -65,6 +102,7 @@
>          return -1;
>
>      case AFailed:
> +    failed:
>          reason = vncrdstring(v);
>          werrstr("%s", reason);
>          if(verbose)
> @@ -72,11 +110,20 @@
>          return -1;
>
>      case ANoAuth:
> +        if(srvversion == 38){
> +            vncwrchar(v, auth);
> +            vncflush(v);
> +        }
>          if(verbose)
>              fprint(2, "no auth needed\n");
>          break;
>
>      case AVncAuth:
> +        if(srvversion == 38){
> +            vncwrchar(v, auth);
> +            vncflush(v);
> +        }
> +
>          vncrdbytes(v, chal, VncChalLen);
>          if(auth_respond(chal, VncChalLen, nil, 0, chal, VncChalLen,
> auth_getkey,
>              "proto=vnc role=client server=%s %s", serveraddr,
> keypattern) != VncChalLen){
> @@ -84,13 +131,20 @@
>          }
>          vncwrbytes(v, chal, VncChalLen);
>          vncflush(v);
> +        break;
> +    }
>
> -        auth = vncrdlong(v);
> +    /* in version 3.8 the auth status is always sent, in 3.3 only in
> AVncAuth */
> +    if(srvversion == 38 || auth == AVncAuth){
> +        auth = vncrdlong(v); /* auth status */
>          switch(auth){
>          default:
>              werrstr("unknown server response 0x%lux", auth);
>              return -1;
>          case VncAuthFailed:
> +            if (srvversion == 38)
> +                goto failed;
> +
>              werrstr("server says authentication failed");
>              return -1;
>          case VncAuthTooMany:
> @@ -99,7 +153,6 @@
>          case VncAuthOK:
>              break;
>          }
> -        break;
>      }
>      return 0;
>  }