range: New http_GetContentRange() semantics

This function returns the content length and puts range indices in
lo and hi arguments. A content length of -1 used to be interpreted
as something to ignore, but there is a case where the content length
may be unknown.

Since we can't represent a zero-length range, because both bounds are
inclusive, zero now denotes the lack of content-range header.

Unknown range units are treated as errors as they wouldn't pass the
busyobj check for the range header, even for pass transactions. The
only way to use "extension" range units is to turn http_range_support
off.

The calling convention for http_GetContentRange() remains otherwise
the same, and for good measure http_GetContentLength() received a
similar description.

Fixes varnishcache#4089

bin/varnishd/cache/cache_http.c

@@ -873,7 +873,14 @@ http_GetHdrField(const struct http *hp, hdr_t hdr,
 	return (i);
 }
 
-/*--------------------------------------------------------------------*/
+/*--------------------------------------------------------------------
+ * Parse content-length header
+ *
+ * Return:
+ *	-2	invalid
+ *	-1	unknown length
+ *	>= 0	body length
+ */
 
 ssize_t
 http_GetContentLength(const struct http *hp)
@@ -895,6 +902,20 @@ http_GetContentLength(const struct http *hp)
 	return (cl);
 }
 
+/*--------------------------------------------------------------------
+ * Parse content-range header
+ *
+ * Return:
+ *	-2	invalid
+ *	-1	unknown length
+ *	0	not applicable
+ *	> 0	full body length
+ *
+ * lo, hi:
+ * 	-1	unknown position
+ * 	>= 0	position
+ */
+
 ssize_t
 http_GetContentRange(const struct http *hp, ssize_t *lo, ssize_t *hi)
 {
@@ -911,14 +932,14 @@ http_GetContentRange(const struct http *hp, ssize_t *lo, ssize_t *hi)
 	*lo = *hi = -1;
 
 	if (!http_GetHdr(hp, H_Content_Range, &b))
-		return (-1);
+		return (0);		// No content-range, ignore
 
 	t = strchr(b, ' ');
 	if (t == NULL)
 		return (-2);		// Missing space after range unit
 
 	if (!http_range_at(b, bytes, t - b))
-		return (-1);		// Unknown range unit, ignore
+		return (-2);		// Unknown range unit
 	b = t + 1;
 
 	if (*b == '*') {		// Content-Range: bytes */123
@@ -937,6 +958,8 @@ http_GetContentRange(const struct http *hp, ssize_t *lo, ssize_t *hi)
 	if (*b != '/')
 		return (-2);
 	if (b[1] == '*') {		// Content-Range: bytes 1-2/*
+		if (*lo == -1 && *hi == -1)
+			return (-2);	// Content-Range: bytes */*
 		cl = -1;
 		b += 2;
 	} else {
@@ -950,10 +973,11 @@ http_GetContentRange(const struct http *hp, ssize_t *lo, ssize_t *hi)
 		return (-2);
 	if (*lo > *hi)
 		return (-2);
-	assert(cl >= -1);
+	if (cl == -1)
+		return (-1);
+	assert(cl > 0);
 	if (*lo >= cl || *hi >= cl)
 		return (-2);
-	AN(cl);
 	return (cl);
 }
 

bin/varnishd/cache/cache_range.c

@@ -265,16 +265,16 @@ VRG_CheckBo(struct busyobj *bo)
 		return (-1);
 	}
 
-	if (crlo < 0 && crhi < 0 && crlen < 0) {
-		AZ(http_GetHdr(bo->beresp, H_Content_Range, NULL));
-		return (0);
-	}
-
-	if (rlo < 0 && rhi < 0) {
+	if (rlo < 0 && rhi < 0 && crlen != 0) {
 		VSLb(bo->vsl, SLT_Error, "Unexpected content-range header");
 		return (-1);
 	}
 
+	if (crlo < 0 && crhi < 0 && crlen == 0) {
+		AZ(http_GetHdr(bo->beresp, H_Content_Range, NULL));
+		return (0);
+	}
+
 	if (crlo < 0) {		// Content-Range: bytes */123
 		assert(crhi < 0);
 		assert(crlen > 0);

bin/varnishtest/tests/c00034.vtc

@@ -134,7 +134,7 @@ varnish v1 -vsl_catchup
 server s1 {
 	loop 2 {
 		rxreq
-		txresp -nolen -hdr "Content-Length: 100"
+		txresp -hdr "Content-Length: 100"
 		send "0123456789"
 		send "0123456789"
 		send "0123456789"
@@ -210,8 +210,13 @@ varnish v1 -vsl_catchup
 server s1 {
 	rxreq
 	txresp
+
 	rxreq
 	txresp -hdr "Accept-Ranges: foobar"
+
+	rxreq
+	expect req.http.Range == foobar=1-2
+	txresp -status 206 -hdr "Content-Range: foobar 1-2/3"
 } -start
 
 varnish v1 -vcl+backend {
@@ -228,10 +233,16 @@ client c7 {
 	rxresp
 	expect resp.http.foobar == ""
 	expect resp.http.accept-ranges == <undef>
+
 	txreq
 	rxresp
 	expect resp.http.foobar == foobar
 	expect resp.http.accept-ranges == foobar
+
+	txreq -hdr "Range: foobar=1-2"
+	rxresp
+	expect resp.status == 503
+	expect resp.http.content-range == <undef>
 } -run
 
 server s1 {
@@ -265,6 +276,18 @@ server s1 {
 	rxreq
 	expect req.http.range == "bytes=0-0"
 	txresp -hdr "content-range: bytes */*" -bodylen 100
+
+	rxreq
+	expect req.http.range == "bytes=0-0"
+	txresp -hdr "content-range: bytes 0-0/*" -bodylen 100
+
+	# issue 4089
+	rxreq
+	expect req.http.range == "bytes=10-19"
+	txresp -status 206 -hdr "content-range: bytes 10-19/*" \
+		-hdr "transfer-encoding: chunked"
+	chunkedlen 10
+	chunkedlen 0
 } -start
 
 varnish v1 -vcl+backend {
@@ -305,6 +328,15 @@ client c8 {
 	txreq -hdr "range: bytes=0-0" -hdr "return: pass"
 	rxresp
 	expect resp.status == 503
+
+	txreq -hdr "range: bytes=0-0" -hdr "return: pass"
+	rxresp
+	expect resp.status == 503
+
+	# issue 4089
+	txreq -hdr "range: bytes=10-19" -hdr "return: pass"
+	rxresp
+	expect resp.status == 206
 } -run
 
 # range filter without a range header