4.x: HttpClient first URI segment is omitted if path starts with //

[romain-grecourt]

Environment Details

• Helidon Version: 4.0.0-M1
• Helidon SE

---

When the path of a URI starts with // the first segment is omitted.
E.g. http://localhost:8080//foo/bar will make a request to /bar !

This is awkward as it is common to have a trailing slash in a URI (E.g. http://localhost:8080/), resolving that URI without normalizing can lead to a path that starts with a double slash.

E.g.

String uri = "http://localhost:8080/"
String baseUri = uri + "/foo/bar";

URI uri = URI.create("http://localhost:8080/")
String baseUri1 = uri + "/foo/bar"; // bad
URI baseUri2 = uri.resolve("/foo/bar"); // good
String baseUri3 = uri.normalize() + "/foo/bar"; // good

---

Reproducer:

WebServer server = WebServer.builder()
        .routing(r -> r.any("/{+}", (req, res) -> res.send(req.requestedUri().path().toString())))
        .build()
        .start();
try {
    Http1Client client = Http1Client.create();
    String baseUri = "http://localhost:" + server.port();
    System.out.println(client.get(baseUri + "//foo/bar").request(String.class).entity());
    // prints /bar
    System.out.println(client.get(baseUri + "/foo/bar").request(String.class).entity());
    // prints /foo/bar
} finally {
    server.stop();
}

---

Note that I ran into this while writing a unit test that retrieved the URI for given socket:

@BeforeAll
static void init(@Socket("backend") URI uri) {
    // uri has a trailing /
}

[tomas-langer]

We also need to support (from conversation with @romain-grecourt, and other expected cases):

WebClient.builder().baseUri("http://localhost:8080//foo/bar")
webclient.get()
 .uri("http://localhost//foo/bar")

This is only for the initial leading / being duplicated, do not fix anywhere else

[danielkec]

@romain-grecourt @tomas-langer This is actually a server issue eg.: URI.create("//foo/bar").normalize().getPath() -> "/bar", do we also want to introduce URI normalization to the client?

To avoid client yielding //foo/bar in the case mentioned by Tomas above?:

WebClient.builder().baseUri("http://localhost:8080//foo/bar").build()
        .get().uri().path()

[danielkec]

Feels like a bug in the java.net.URI - JDK-8316799

[danielkec]

Huh not really a JDK bug, TIL about net_path //foo is a net_path as defined by RFC 2396

absoluteURI = scheme ":" ( hier_part | opaque_part )
hier_part = ( net_path | abs_path ) [ "?" query ]
net_path = "//" authority [ abs_path ]
abs_path = "/" path_segments
opaque_part = uric_no_slash *uric
uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |"&" | "=" | "+" | "$" | ","