// portal. If it is considered a captive portal, a different sign-in URL
// is needed (i.e. can't browse a 204). This could be the result of an HTTP
// proxy server.
-
- // Consider 200 response with "Content-length=0" to not be a captive portal.
- // There's no point in considering this a captive portal as the user cannot
- // sign-in to an empty page. Probably the result of a broken transparent proxy.
- // See http://b/9972012.
- if (httpResponseCode == 200 && urlConnection.getContentLength() == 0) {
- validationLog("Empty 200 response interpreted as 204 response.");
- httpResponseCode = 204;
- }
-
- if (httpResponseCode == 200 && probeType == ValidationProbeEvent.PROBE_PAC) {
- validationLog("PAC fetch 200 response interpreted as 204 response.");
- httpResponseCode = 204;
+ if (httpResponseCode == 200) {
+ if (probeType == ValidationProbeEvent.PROBE_PAC) {
+ validationLog("PAC fetch 200 response interpreted as 204 response.");
+ httpResponseCode = 204;
+ } else if (urlConnection.getContentLengthLong() == 0) {
+ // Consider 200 response with "Content-length=0" to not be a captive portal.
+ // There's no point in considering this a captive portal as the user cannot
+ // sign-in to an empty page. Probably the result of a broken transparent proxy.
+ // See http://b/9972012.
+ validationLog(
+ "200 response with Content-length=0 interpreted as 204 response.");
+ httpResponseCode = 204;
+ } else if (urlConnection.getContentLengthLong() == -1) {
+ // When no Content-length (default value == -1), attempt to read a byte from the
+ // response. Do not use available() as it is unreliable. See http://b/33498325.
+ if (urlConnection.getInputStream().read() == -1) {
+ validationLog("Empty 200 response interpreted as 204 response.");
+ httpResponseCode = 204;
+ }
+ }
}
} catch (IOException e) {
validationLog("Probably not a portal: exception " + e);