From fa64b0fc4bb8e25fd831db8b9328eeec5cc209c1 Mon Sep 17 00:00:00 2001 From: Jay Satiro Date: Tue, 7 Nov 2017 00:46:59 -0500 Subject: [PATCH] content_encoding: fix inflate_stream for no bytes available - Don't call zlib's inflate() when avail_in stream bytes is 0. This is a follow up to the parent commit 19e66e5. Prior to that change libcurl's inflate_stream could call zlib's inflate even when no bytes were available, causing inflate to return Z_BUF_ERROR, and then inflate_stream would treat that as a hard error and return CURLE_BAD_CONTENT_ENCODING. According to the zlib FAQ, Z_BUF_ERROR is not fatal. This bug would happen randomly since packet sizes are arbitrary. A test of 10,000 transfers had 55 fail (ie 0.55%). Ref: https://zlib.net/zlib_faq.html#faq05 Closes https://github.com/curl/curl/pull/2060 --- lib/content_encoding.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/lib/content_encoding.c b/lib/content_encoding.c index 904dff526..626bb8ec9 100644 --- a/lib/content_encoding.c +++ b/lib/content_encoding.c @@ -139,6 +139,11 @@ inflate_stream(struct connectdata *conn, contenc_writer *writer) /* because the buffer size is fixed, iteratively decompress and transfer to the client via client_write. */ for(;;) { + if(z->avail_in == 0) { + free(decomp); + return result; + } + /* (re)set buffer for decompressed output for every iteration */ z->next_out = (Bytef *) decomp; z->avail_out = DSIZ; @@ -163,10 +168,7 @@ inflate_stream(struct connectdata *conn, contenc_writer *writer) /* Done with these bytes, exit */ /* status is always Z_OK at this point! */ - if(z->avail_in == 0) { - free(decomp); - return result; - } + continue; } else if(allow_restart && status == Z_DATA_ERROR) { /* some servers seem to not generate zlib headers, so this is an attempt