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Add If-Match support with 412 response for precondition failures, imp… #155

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52 changes: 50 additions & 2 deletions src/main/java/org/juv25d/handler/StaticFileHandler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,40 @@ public static HttpResponse handle(HttpRequest request) {

String etag = computeStrongEtag(fileContent);

String ifMatch = getHeaderIgnoreCase(request.headers(), "If-Match");
if (ifMatch != null && !ifMatch.isBlank() && !etagMatches(ifMatch, etag)) {
Map<String, String> headers = new HashMap<>();
headers.put("Content-Type", "text/html; charset=utf-8");
headers.put("ETag", etag);
headers.put("Cache-Control", "public, max-age=" + MAX_AGE_SECONDS);

String html = """
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>412 Precondition Failed</title>
<style>
body {
font-family: Arial, sans-serif;
max-width: 600px;
margin: 100px auto;
text-align: center;
}
h1 { color: #e67e22; }
</style>
</head>
<body>
<h1>412 - Precondition Failed</h1>
<p>The requested resource did not match the supplied <code>If-Match</code> precondition.</p>
</body>
</html>
""";

logger.info("If-Match precondition failed for " + resourcePath + " -> 412 Precondition Failed");
return new HttpResponse(412, "Precondition Failed", headers, html.getBytes(StandardCharsets.UTF_8));
}

String ifNoneMatch = getHeaderIgnoreCase(request.headers(), "If-None-Match");
if (etagMatches(ifNoneMatch, etag)) {
Map<String, String> headers = new HashMap<>();
Expand Down Expand Up @@ -202,7 +236,16 @@ private static String toHex(byte[] bytes) {
@Nullable private static String opaqueTag(@Nullable String etag) {
if (etag == null) return null;
String e = etag.trim();
return e.startsWith("W/") ? e.substring(2) : e;

if (e.startsWith("W/")) {
e = e.substring(2).trim();
}

if (e.length() >= 2 && e.startsWith("\"") && e.endsWith("\"")) {
e = e.substring(1, e.length() - 1);
}

return e;
}

private static boolean etagMatches(@Nullable String ifNoneMatchHeader, String currentEtag) {
Expand All @@ -214,10 +257,15 @@ private static boolean etagMatches(@Nullable String ifNoneMatchHeader, String cu
return true;
}

String current = opaqueTag(currentEtag);
if (current == null) {
return false;
}

String[] parts = value.split(",");
for (String part : parts) {
String tag = opaqueTag(part);
if (part != null && tag != null && tag.equals(opaqueTag(currentEtag))) {
if (tag != null && tag.equals(current)) {
return true;
}
}
Expand Down
80 changes: 80 additions & 0 deletions src/test/java/org/juv25d/handler/StaticFileHandlerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,86 @@ void shouldReturn304WhenIfNoneMatchMatchesEtag() {
assertThat(secondResponse.headers()).containsEntry("Cache-Control", "public, max-age=5");
}

@Test
void shouldReturn412WhenIfMatchDoesNotMatch() {
HttpRequest first = createRequest("GET", "/index.html");
HttpResponse firstResponse = StaticFileHandler.handle(first);

assertThat(firstResponse.statusCode()).isEqualTo(200);
String etag = firstResponse.headers().get("ETag");
assertThat(etag).isNotBlank();

Map<String, String> headers = new HashMap<>();
headers.put("If-Match", "\"definitely-not-the-real-etag\"");

HttpRequest second = createRequest("GET", "/index.html", headers);
HttpResponse secondResponse = StaticFileHandler.handle(second);

assertThat(secondResponse.statusCode()).isEqualTo(412);
assertThat(secondResponse.statusText()).isEqualTo("Precondition Failed");
assertThat(secondResponse.headers()).containsEntry("ETag", etag);
assertThat(secondResponse.headers()).containsEntry("Cache-Control", "public, max-age=5");
assertThat(secondResponse.body()).isNotEmpty();
}

@Test
void shouldReturn200WhenIfMatchMatches() {
HttpRequest first = createRequest("GET", "/index.html");
HttpResponse firstResponse = StaticFileHandler.handle(first);

assertThat(firstResponse.statusCode()).isEqualTo(200);
String etag = firstResponse.headers().get("ETag");
assertThat(etag).isNotBlank();

Map<String, String> headers = new HashMap<>();
headers.put("If-Match", etag);

HttpRequest second = createRequest("GET", "/index.html", headers);
HttpResponse secondResponse = StaticFileHandler.handle(second);

assertThat(secondResponse.statusCode()).isEqualTo(200);
assertThat(secondResponse.statusText()).isEqualTo("OK");
}

@Test
void shouldPreferIfMatchOverIfNoneMatch() {
Map<String, String> headers = new HashMap<>();
headers.put("If-Match", "\"nope\"");
headers.put("If-None-Match", "*");

HttpRequest request = createRequest("GET", "/index.html", headers);
HttpResponse response = StaticFileHandler.handle(request);

assertThat(response.statusCode()).isEqualTo(412);
assertThat(response.statusText()).isEqualTo("Precondition Failed");
}

@Test
void shouldReturn200WhenIfMatchMatchesEvenIfUnquoted() {
HttpRequest first = createRequest("GET", "/index.html");
HttpResponse firstResponse = StaticFileHandler.handle(first);

assertThat(firstResponse.statusCode()).isEqualTo(200);
String etag = requireHeader(firstResponse, "ETag");
assertThat(etag).isNotBlank();

String unquoted = etag.replace("\"", "");

Map<String, String> headers = new HashMap<>();
headers.put("If-Match", unquoted);

HttpRequest second = createRequest("GET", "/index.html", headers);
HttpResponse secondResponse = StaticFileHandler.handle(second);

assertThat(secondResponse.statusCode()).isEqualTo(200);
assertThat(secondResponse.statusText()).isEqualTo("OK");
}

private String requireHeader(HttpResponse response, String headerName) {
assertThat(response.headers()).containsKey(headerName);
return java.util.Objects.requireNonNull(response.headers().get(headerName));
}

@Test
void shouldReturn404ForNonExistingFile() {
HttpRequest request = createRequest("GET", "/nonexistent.html");
Expand Down