dot upstreams: per-upstream tls_name for sni and cert verification by dns name

src/storage/migrations.zig

@@ -18,10 +18,19 @@ const log = std.log.scoped(.migrations);
 
 pub const Step = struct { version: u32, sql: [:0]const u8 };
 
+/// Append only. Editing a released step — or `config_schema.ddl_v1` — would make
+/// a fresh database and an upgraded one disagree, and nothing would detect it.
 pub const steps = [_]Step{
     .{ .version = 1, .sql = config_schema.ddl_v1 },
+    .{ .version = 2, .sql = ddl_v2 },
 };
 
+/// The DoT verification name (`upstreams.tls_name`). Empty keeps the pre-step-2
+/// behavior: verify the certificate against the url host.
+const ddl_v2: [:0]const u8 =
+    \\ALTER TABLE upstreams ADD COLUMN tls_name TEXT NOT NULL DEFAULT '';
+;
+
 pub const target_version: u32 = steps[steps.len - 1].version;
 
 comptime {
@@ -236,6 +245,63 @@ test "a stepwise upgrade applies only the new steps" {
     try testing.expectEqual(@as(i64, 1), try database.queryInt("SELECT count(*) FROM groups"));
 }
 
+fn columnExists(database: *db.Db, table: []const u8, column: []const u8) !bool {
+    var stmt = try database.prepare("SELECT count(*) FROM pragma_table_info(?1) WHERE name = ?2");
+    defer stmt.deinit();
+    try stmt.bindText(1, table);
+    try stmt.bindText(2, column);
+    if (!try stmt.step()) return error.SqliteError;
+    return stmt.columnInt(0) != 0;
+}
+
+test "a fresh database reaches version 2 with the tls_name column" {
+    var database = try openMigrated();
+    defer database.close();
+
+    try testing.expectEqual(@as(u32, 2), try migrate(&database));
+    try testing.expectEqual(@as(u32, 2), target_version);
+    try testing.expect(try columnExists(&database, "upstreams", "tls_name"));
+}
+
+test "a version 1 database upgrades to 2 and keeps its rows with an empty tls_name" {
+    var database = try openMigrated();
+    defer database.close();
+
+    const first = [_]Step{.{ .version = 1, .sql = config_schema.ddl_v1 }};
+    try testing.expectEqual(@as(u32, 1), try migrateSteps(&database, &first));
+    try testing.expect(!try columnExists(&database, "upstreams", "tls_name"));
+    try database.exec("INSERT INTO upstreams (url, priority, enabled) VALUES ('tls://1.1.1.1:853', 10, 1);");
+
+    try testing.expectEqual(@as(u32, 2), try migrate(&database));
+    try testing.expectEqual(@as(u32, 2), try readVersion(&database));
+    try testing.expect(try columnExists(&database, "upstreams", "tls_name"));
+
+    var stmt = try database.prepare("SELECT url, tls_name FROM upstreams");
+    defer stmt.deinit();
+    try testing.expect(try stmt.step());
+    try testing.expectEqualStrings("tls://1.1.1.1:853", stmt.columnText(0));
+    try testing.expectEqualStrings("", stmt.columnText(1));
+}
+
+test "a failing step after step 2 rolls back the whole upgrade from version 1" {
+    var database = try openMigrated();
+    defer database.close();
+
+    const first = [_]Step{.{ .version = 1, .sql = config_schema.ddl_v1 }};
+    _ = try migrateSteps(&database, &first);
+
+    const broken = [_]Step{
+        steps[0],
+        steps[1],
+        .{ .version = 3, .sql = "CREATE TABLE third (" },
+    };
+    try testing.expectError(error.Unexpected, migrateSteps(&database, &broken));
+
+    // One transaction: the ALTER TABLE of step 2 went back with step 3.
+    try testing.expect(!try columnExists(&database, "upstreams", "tls_name"));
+    try testing.expectEqual(@as(u32, 1), try readVersion(&database));
+}
+
 test "delete_order and content_tables name exactly the tables the schema creates" {
     var database = try openMigrated();
     defer database.close();