BUG/MEDIUM: cache: Fix hash collision in `accept-encoding` handling for `Vary`
This patch fixes GitHub Issue #988. Commit ce9e7b25217c46db1ac636b2c885a05bf91ae57e
was not sufficient, because it fell back to a hash comparison if the bitmap
of known encodings was not acceptable instead of directly returning the the
cached response is not compatible.
This patch also extends the reg-test to test the hash collision that was
mentioned in #988.
Vary handling is 2.4, no backport needed.
diff --git a/reg-tests/cache/vary_accept_encoding.vtc b/reg-tests/cache/vary_accept_encoding.vtc
index afd2cfb..59e819a 100644
--- a/reg-tests/cache/vary_accept_encoding.vtc
+++ b/reg-tests/cache/vary_accept_encoding.vtc
@@ -73,6 +73,21 @@
-hdr "Cache-Control: max-age=5" \
-hdr "Content-Encoding: unknown_encoding" \
-bodylen 119
+
+
+ rxreq
+ expect req.url == "/hash-collision"
+ txresp -hdr "Vary: accept-encoding" \
+ -hdr "Cache-Control: max-age=5" \
+ -hdr "Content-Encoding: br" \
+ -bodylen 129
+
+ rxreq
+ expect req.url == "/hash-collision"
+ txresp -hdr "Vary: accept-encoding" \
+ -hdr "Cache-Control: max-age=5" \
+ -hdr "Content-Encoding: gzip" \
+ -bodylen 139
} -start
@@ -300,4 +315,21 @@
expect resp.bodylen == 119
expect resp.http.X-Cache-Hit == 0
+ #
+ # Hash collision (https://github.com/haproxy/haproxy/issues/988)
+ #
+ # crc32(gzip) ^ crc32(br) ^ crc32(xxx) ^ crc32(jdcqiab) == crc32(gzip)
+ txreq -url "/hash-collision" -hdr "Accept-Encoding: br,gzip,xxx,jdcqiab"
+ rxresp
+ expect resp.status == 200
+ expect resp.http.content-encoding == "br"
+ expect resp.bodylen == 129
+ expect resp.http.X-Cache-Hit == 0
+
+ txreq -url "/hash-collision" -hdr "Accept-Encoding: gzip"
+ rxresp
+ expect resp.status == 200
+ expect resp.http.content-encoding == "gzip"
+ expect resp.bodylen == 139
+ expect resp.http.X-Cache-Hit == 0
} -run