Build Url using ServletUriComponentsBuilder without port number in Spring - spring

Question

I am using ServletUriComponentsBuilder in my service class to build some urls but the problem is that it includes port number also where the servlet container is running, this is a problem when I am deploying my app on production behind a proxy server which is supposed to run only on port 80
Code that I am using is:
String sUri = ServletUriComponentsBuilder.fromCurrentContextPath().path("/student/edit/" + st.getId()).build().toUriString();
While c:url that I am using in JSP is working perfectly fine, it do not include port number. Is there any way by which ServletUriComponentsBuilder also start detects whether it needs to include port number or not.
Means if the application start on port 8080 then it can include port number but when app is accessed from port 80 then do not include?
Whats happening: If my tomcat is running on port 8080 while I have proxy server in place which serves request on port 80, but urls built by ServletUriComponentsBuilder still appends port 8080 after host, I need it to be 80

Answer 1

Take a look at ServletUriComponentsBuilder#fromRequest:
String scheme = request.getScheme();
int port = request.getServerPort();
String host = request.getServerName();
String header = request.getHeader("X-Forwarded-Host");
if (StringUtils.hasText(header)) {
String[] hosts = StringUtils.commaDelimitedListToStringArray(header);
String hostToUse = hosts[0];
if (hostToUse.contains(":")) {
String[] hostAndPort = StringUtils.split(hostToUse, ":");
host = hostAndPort[0];
port = Integer.parseInt(hostAndPort[1]);
}
else {
host = hostToUse;
}
}
....
Especially the line
String header = request.getHeader("X-Forwarded-Host");
will do the trick. All you have to do is set X-Forwarded-Host in your proxy server and start using ServletUriComponentsBuilder#fromRequest instead of ServletUriComponentsBuilder#fromCurrentContextPath. Your url should contain your public proxy hostname and no port.

Answer 2

This is a bug from this method:
public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request) {
String scheme = request.getScheme();
int port = request.getServerPort();
String host = request.getServerName();
String header = request.getHeader("X-Forwarded-Host");
if (StringUtils.hasText(header)) {
String[] hosts = StringUtils.commaDelimitedListToStringArray(header);
String hostToUse = hosts[0];
if (hostToUse.contains(":")) {
String[] hostAndPort = StringUtils.split(hostToUse, ":");
host = hostAndPort[0];
port = Integer.parseInt(hostAndPort[1]);
}
else {
host = hostToUse;
}
}
ServletUriComponentsBuilder builder = new ServletUriComponentsBuilder();
builder.scheme(scheme);
builder.host(host);
if ((scheme.equals("http") && port != 80) || (scheme.equals("https") && port != 443)) {
builder.port(port);
}
builder.pathFromRequest(request);
builder.query(request.getQueryString());
return builder;
}
If X-Forwarded-Host is filled, and there is no port it's because we are on the port 80. But the else
else {
host = hostToUse;
}
So this case is a mixed case where the host is readed from the X-Forwarded-Host value but the port is read directly from the request (and it's the request the apache use to call tomcat).
We are working this issue here and did'nt find any alternative way to write a new UriComponentsBuilder (ok... maybe juste extends!)