Guard web-logger uriList[2] reads so a missing month segment can't crash the handler

ft8af/app/src/main/java/com/k1af/ft8af/html/LogHttpServer.java

@@ -86,6 +86,33 @@ static int normalizePageSize(int pageSize) {
         return pageSize > 0 ? pageSize : 100;
     }
 
+    /**
+     * The request path segment at {@code index} (from {@code getUri().split("/")}),
+     * or {@code null} when the request has no such segment.
+     *
+     * <p>Every {@code uriList[2]} read in {@link #serve} routes through this so a
+     * request that omits the trailing segment falls back to the default page instead
+     * of throwing {@link ArrayIndexOutOfBoundsException}. {@code GET /SHOWQSL} split to
+     * {@code ["", "SHOWQSL"]} (length 2), so the old bare {@code uriList[2]} threw — and
+     * for SHOWQSL that read sat <em>outside</em> the try/catch, so it escaped
+     * {@code serve} uncaught; for the DOWNQSL / DOWNQSLNOQSL {@code Content-Disposition}
+     * header it threw inside the try and returned an opaque HTTP 500 even though the
+     * body branch had already fallen back correctly. Mirrors the {@code uriList.length
+     * >= 3} guard the DELFOLLOW / DELQSL / DELQSLCALLSIGN branches already use.
+     */
+    static String uriSegment(String[] uriList, int index) {
+        return uriList != null && index >= 0 && index < uriList.length ? uriList[index] : null;
+    }
+
+    /**
+     * {@code Content-Disposition} filename for a per-month QSL download. Falls back to
+     * {@code log.adi} when the month segment is absent (see {@link #uriSegment}), rather
+     * than reading a missing path segment.
+     */
+    static String downloadFileName(String month) {
+        return String.format("log%s.adi", month != null ? month : "");
+    }
+
     @Override
     public Response serve(IHTTPSession session) {
         String[] uriList = session.getUri().split("/");
@@ -146,7 +173,8 @@ public Response serve(IHTTPSession session) {
         } else if (uri.equalsIgnoreCase("SHOWALLQSL")) {
             msg = HTML_STRING(showAllQSL());
         } else if (uri.equalsIgnoreCase("SHOWQSL")) {
-            msg = HTML_STRING(showQSLByMonth(uriList[2]));
+            String month = uriSegment(uriList, 2);
+            msg = month != null ? HTML_STRING(showQSLByMonth(month)) : HtmlContext.DEFAULT_HTML();
         } else if (uri.equalsIgnoreCase("DELQSLCALLSIGN")) {//Delete a QSO callsign
             if (uriList.length >= 3) {
                 deleteQSLCallSign(uriList[2].replace("_", "/"));
@@ -164,22 +192,24 @@ public Response serve(IHTTPSession session) {
                 response = newFixedLengthResponse(NanoHTTPD.Response.Status.OK, "text/plain", msg);
                 response.addHeader("Content-Disposition", "attachment;filename=All_log.adi");
             } else if (uri.equalsIgnoreCase("DOWNQSL")) {
-                if (uriList.length >= 3) {
-                    msg = downQSLByMonth(uriList[2], true);
+                String month = uriSegment(uriList, 2);
+                if (month != null) {
+                    msg = downQSLByMonth(month, true);
                 } else {
                     msg = HtmlContext.DEFAULT_HTML();
                 }
                 response = newFixedLengthResponse(NanoHTTPD.Response.Status.OK, "text/plain", msg);
-                response.addHeader("Content-Disposition", String.format("attachment;filename=log%s.adi", uriList[2]));
+                response.addHeader("Content-Disposition", "attachment;filename=" + downloadFileName(month));
 
             } else if (uri.equalsIgnoreCase("DOWNQSLNOQSL")) {
-                if (uriList.length >= 3) {
-                    msg = downQSLByMonth(uriList[2], false);
+                String month = uriSegment(uriList, 2);
+                if (month != null) {
+                    msg = downQSLByMonth(month, false);
                 } else {
                     msg = HtmlContext.DEFAULT_HTML();
                 }
                 response = newFixedLengthResponse(NanoHTTPD.Response.Status.OK, "text/plain", msg);
-                response.addHeader("Content-Disposition", String.format("attachment;filename=log%s.adi", uriList[2]));
+                response.addHeader("Content-Disposition", "attachment;filename=" + downloadFileName(month));
 
             } else {
                 response = newFixedLengthResponse(msg);

ft8af/app/src/test/java/com/k1af/ft8af/html/LogHttpServerUriSegmentTest.java

@@ -0,0 +1,70 @@
+package com.k1af.ft8af.html;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import org.junit.Test;
+
+/**
+ * Pure-logic coverage for {@link LogHttpServer#uriSegment(String[], int)} and
+ * {@link LogHttpServer#downloadFileName(String)}, the guards that keep the
+ * web-logbook {@code serve} dispatch from reading a missing {@code uriList[2]}
+ * path segment.
+ *
+ * <p>Regression: {@code GET /SHOWQSL} (no trailing month) split to
+ * {@code ["", "SHOWQSL"]} and the bare {@code uriList[2]} read threw
+ * {@link ArrayIndexOutOfBoundsException}. For SHOWQSL that read was outside the
+ * {@code serve} try/catch, so it escaped the handler entirely; the
+ * DOWNQSL / DOWNQSLNOQSL {@code Content-Disposition} header read threw inside the
+ * try and returned an opaque HTTP 500 even though the body branch had already
+ * fallen back to the default page. The three guarded sibling branches
+ * (DELFOLLOW / DELQSL / DELQSLCALLSIGN) already used {@code uriList.length >= 3}.
+ *
+ * <p>These tests reproduce the exact {@code getUri().split("/")} shape and pin the
+ * guarded behaviour. No Android types are touched, so no Robolectric runner is
+ * needed.
+ */
+public class LogHttpServerUriSegmentTest {
+
+    @Test
+    public void missingTrailingSegment_isNull() {
+        // "/SHOWQSL".split("/") == ["", "SHOWQSL"] (length 2), so index 2 is absent.
+        String[] uriList = "/SHOWQSL".split("/");
+        assertThat(uriList).hasLength(2);
+        assertThat(LogHttpServer.uriSegment(uriList, 2)).isNull();
+    }
+
+    @Test
+    public void presentTrailingSegment_isReturned() {
+        String[] uriList = "/SHOWQSL/202401".split("/");
+        assertThat(LogHttpServer.uriSegment(uriList, 2)).isEqualTo("202401");
+    }
+
+    @Test
+    public void downloadMissingMonth_isNull() {
+        // The DOWNQSL Content-Disposition header used to dereference this unconditionally.
+        assertThat(LogHttpServer.uriSegment("/DOWNQSL".split("/"), 2)).isNull();
+        assertThat(LogHttpServer.uriSegment("/DOWNQSLNOQSL".split("/"), 2)).isNull();
+    }
+
+    @Test
+    public void outOfRangeAndDegenerateInputs_areNull() {
+        String[] one = {"", "SHOWQSL"};
+        assertThat(LogHttpServer.uriSegment(one, 5)).isNull();
+        assertThat(LogHttpServer.uriSegment(one, -1)).isNull();
+        assertThat(LogHttpServer.uriSegment(new String[0], 0)).isNull();
+        assertThat(LogHttpServer.uriSegment(null, 2)).isNull();
+    }
+
+    @Test
+    public void downloadFileName_usesMonthWhenPresent() {
+        // Identical to the old String.format("log%s.adi", uriList[2]) when the month exists.
+        assertThat(LogHttpServer.downloadFileName("202401")).isEqualTo("log202401.adi");
+        assertThat(LogHttpServer.downloadFileName("")).isEqualTo("log.adi");
+    }
+
+    @Test
+    public void downloadFileName_fallsBackWhenMonthMissing() {
+        // A bare GET /DOWNQSL must produce a sane filename, not crash the header build.
+        assertThat(LogHttpServer.downloadFileName(null)).isEqualTo("log.adi");
+    }
+}