Apply the same Deflate decoder fix as PuTTY r10278.

This causes sensible error reporting if distance codes 30 or 31 appear
in a compressed block.

(Not that Halibut actually _uses_ the Deflate decoder - it only uses
the encoder - but if I've got a copy of this code here then it should
be correct.)

[originally from svn r10280]
[r10278 == 3fd8014ea7235d0ec34e8f97a34f3ecf576e8239 in putty repository]

1 files changed, 4 insertions, 0 deletions

diff --git a/deflate.c b/deflate.c
index 5eb1faa..7c3f3bc 100644
--- a/deflate.c
+++ b/deflate.c
@@ -2417,6 +2417,10 @@ int deflate_decompress_data(deflate_decompress_ctx *dctx,
 	    debug(("recv: dist %d\n", code));
 	    if (code == -1)
 		goto finished;
+            if (code >= 30) {
+		error = DEFLATE_ERR_BADDISTCODE;
+                goto finished;
+            }
 	    dctx->state = GOTDISTSYM;
 	    dctx->sym = code;
 	    break;