feat(controller-peers-env-fallback): route the controller's two identity loops through the shared lookup (task 2.1)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.kiro/specs/controller-peers-env-fallback/tasks.md

@@ -22,7 +22,7 @@
   - Done when, after `/xce-build` (controller, scheduler, worker, harness) on a machine with no local cluster, the script runs with no cases and exits 0, and exits non-zero with the pre-flight message while a listener is bound to port 9990 or when pointed at a build directory missing a binary
 
 - [ ] 2. Controller
-- [ ] 2.1 Route the controller's two existing identity loops through the shared lookup
+- [x] 2.1 Route the controller's two existing identity loops through the shared lookup
   - Replace the loop that picks the controller's election priority, keeping the existing "at least one candidate" guard so a standalone controller still gets priority 0, and keeping "no match gives the last index" at that call site
   - Replace the loop that picks the listen port, keeping the existing "no match with a peers list refuses to start" and "port 0 falls back to the default port" behavior
   - Pure refactor: no behavior change for any input

src/controller/cluster.c

@@ -1780,16 +1780,9 @@ int cluster_init_phase1(cluster_t* c)
     int my_priority = 0;
     const xce_cluster_config_t* pcfg = &c->myconf->peers_cfg;
     if (pcfg->candidates_count > 0) {
-        my_priority = pcfg->candidates_count - 1; /* default: last = lowest */
+        /* No match: last index = lowest priority. */
-        for (int i = 0; i < pcfg->candidates_count; i++) {
+        int idx     = xce_peers_find_identity(pcfg, c->myconf->name);
-            const char* key = pcfg->candidates[i].name[0]
+        my_priority = idx >= 0 ? idx : pcfg->candidates_count - 1;
-                                  ? pcfg->candidates[i].name
-                                  : pcfg->candidates[i].hostname;
-            if (strncmp(key, c->myconf->name, XCE_MAXNAME_LEN - 1) == 0) {
-                my_priority = i;
-                break;
-            }
-        }
         INFO("HA peers: %d candidates, my_priority=%d (name=%s)",
              pcfg->candidates_count, my_priority, c->myconf->name);
     }
@@ -1873,7 +1866,8 @@ int cluster_open_listener(cluster_t* c)
         return 0;
 
     /* Determine listen port:
-     *   1. Search --peers candidates for the local name.
+     *   1. Look up the local name among the --peers candidates
+     *      (xce_peers_find_identity()).
      *      - Matched with a nonzero port: bind to it (unchanged happy
      *        path; also how a single-node operator gets a custom port,
      *        via a single self-referencing --peers entry).
@@ -1889,16 +1883,9 @@ int cluster_open_listener(cluster_t* c)
     bool     matched = false;
     {
         const xce_cluster_config_t* pcfg = &c->myconf->peers_cfg;
-        for (int j = 0; j < pcfg->candidates_count; j++) {
+        int idx = xce_peers_find_identity(pcfg, c->myconf->name);
-            const char* key = pcfg->candidates[j].name[0]
+        matched = idx >= 0;
-                                  ? pcfg->candidates[j].name
+        my_port = matched ? (uint32_t)pcfg->candidates[idx].port : 0;
-                                  : pcfg->candidates[j].hostname;
-            if (strncmp(key, c->myconf->name, XCE_MAXNAME_LEN - 1) == 0) {
-                my_port = pcfg->candidates[j].port;
-                matched = true;
-                break;
-            }
-        }
 
         if (!matched && pcfg->candidates_count > 0) {
             ERROR("cluster_open_listener: local name '%s' not found in "

src/controller/testsuite/test_ha_cluster.c

@@ -9,11 +9,19 @@
  * Instead they manually zero-init cluster_t and call ha_init() on c.ha directly.
  */
 
+#include <arpa/inet.h>
+#include <errno.h>
+#include <netinet/in.h>
 #include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
 
 #include <unity/unity.h>
 
+#include "cluster.h"
 #include "ha.h"
 #include "xce/cluster_def.h"
 
@@ -138,6 +146,130 @@ static void test_hooks_registered_guard_prevents_double_register(void)
     printf("test_hooks_registered_guard_prevents_double_register: PASS\n");
 }
 
+/* ── cluster_open_listener(): which --peers candidate is this controller ──
+ *
+ * Characterization tests (controller-peers-env-fallback task 2.1): pin the
+ * listener's candidate match before it is routed through
+ * xce_peers_find_identity().  The key is the candidate's name, or its
+ * hostname when unnamed; a match binds that candidate's port, and no match
+ * with a non-empty --peers list refuses to start without opening a socket.
+ * The port-0/standalone default-port fallback is left out: it binds a fixed
+ * port (9990) that another process on this host may hold. */
+
+static void listener_set_candidate(xce_cluster_config_t* cfg, int i,
+                                   const char* name, const char* hostname,
+                                   int port)
+{
+    snprintf(cfg->candidates[i].name, XCE_MAXNAME_LEN, "%s", name);
+    snprintf(cfg->candidates[i].hostname, XCE_MAXHOSTNAME_LEN, "%s",
+             hostname);
+    cfg->candidates[i].port = port;
+}
+
+/* A zeroed cluster_t with only what cluster_open_listener() reads. */
+static cluster_t* listener_make_cluster(myconf_t* conf, const char* name)
+{
+    cluster_t* c = calloc(1, sizeof(*c));
+    TEST_ASSERT_NOT_NULL(c);
+    memset(conf, 0, sizeof(*conf));
+    conf->name = (char*)name;
+    c->myconf  = conf;
+    c->myhost  = &c->myhost_info;
+    c->ep.fd   = -1;
+    return c;
+}
+
+/* An unused TCP port: bind port 0, read it back, release it. */
+static int listener_free_port(void)
+{
+    struct sockaddr_in sa;
+    socklen_t          len = sizeof(sa);
+    int                fd  = socket(AF_INET, SOCK_STREAM, 0);
+    TEST_ASSERT_TRUE(fd >= 0);
+    memset(&sa, 0, sizeof(sa));
+    sa.sin_family      = AF_INET;
+    sa.sin_addr.s_addr = htonl(INADDR_ANY);
+    sa.sin_port        = 0;
+    TEST_ASSERT_EQUAL_INT(0, bind(fd, (struct sockaddr*)&sa, sizeof(sa)));
+    TEST_ASSERT_EQUAL_INT(0, getsockname(fd, (struct sockaddr*)&sa, &len));
+    close(fd);
+    return ntohs(sa.sin_port);
+}
+
+static int listener_bound_port(int fd)
+{
+    struct sockaddr_in sa;
+    socklen_t          len = sizeof(sa);
+    TEST_ASSERT_EQUAL_INT(0, getsockname(fd, (struct sockaddr*)&sa, &len));
+    return ntohs(sa.sin_port);
+}
+
+static void test_open_listener_binds_named_candidate_port(void)
+{
+    myconf_t   conf;
+    cluster_t* c    = listener_make_cluster(&conf, "ctrl-b");
+    int        port = listener_free_port();
+
+    conf.peers_cfg.candidates_count = 2;
+    listener_set_candidate(&conf.peers_cfg, 0, "ctrl-a", "localhost", 1);
+    listener_set_candidate(&conf.peers_cfg, 1, "ctrl-b", "localhost", port);
+
+    TEST_ASSERT_EQUAL_INT(0, cluster_open_listener(c));
+    TEST_ASSERT_TRUE(c->ep.fd >= 0);
+    TEST_ASSERT_EQUAL_INT(port, listener_bound_port(c->ep.fd));
+
+    close(c->ep.fd);
+    free(c);
+}
+
+static void test_open_listener_matches_unnamed_candidate_by_hostname(void)
+{
+    myconf_t   conf;
+    cluster_t* c    = listener_make_cluster(&conf, "node7");
+    int        port = listener_free_port();
+
+    conf.peers_cfg.candidates_count = 2;
+    listener_set_candidate(&conf.peers_cfg, 0, "ctrl-a", "localhost", 1);
+    listener_set_candidate(&conf.peers_cfg, 1, "", "node7", port);
+
+    TEST_ASSERT_EQUAL_INT(0, cluster_open_listener(c));
+    TEST_ASSERT_TRUE(c->ep.fd >= 0);
+    TEST_ASSERT_EQUAL_INT(port, listener_bound_port(c->ep.fd));
+
+    close(c->ep.fd);
+    free(c);
+}
+
+static void test_open_listener_refuses_when_name_not_in_peers(void)
+{
+    myconf_t   conf;
+    cluster_t* c = listener_make_cluster(&conf, "ctrl-z");
+
+    conf.peers_cfg.candidates_count = 2;
+    listener_set_candidate(&conf.peers_cfg, 0, "ctrl-a", "localhost", 1);
+    listener_set_candidate(&conf.peers_cfg, 1, "ctrl-b", "localhost", 2);
+
+    TEST_ASSERT_EQUAL_INT(-EINVAL, cluster_open_listener(c));
+    TEST_ASSERT_EQUAL_INT(-1, c->ep.fd);
+
+    free(c);
+}
+
+/* A named candidate is never matched by its hostname. */
+static void test_open_listener_ignores_hostname_of_named_candidate(void)
+{
+    myconf_t   conf;
+    cluster_t* c = listener_make_cluster(&conf, "node7");
+
+    conf.peers_cfg.candidates_count = 1;
+    listener_set_candidate(&conf.peers_cfg, 0, "ctrl-a", "node7", 1);
+
+    TEST_ASSERT_EQUAL_INT(-EINVAL, cluster_open_listener(c));
+    TEST_ASSERT_EQUAL_INT(-1, c->ep.fd);
+
+    free(c);
+}
+
 void test_ha_cluster(void)
 {
     UnitySetTestFile(__FILE__);
@@ -146,4 +278,8 @@ void test_ha_cluster(void)
     RUN_TEST(test_ha_demote_to_standby_uses_c_ha);
     RUN_TEST(test_ha_promote_increments_term_via_cluster);
     RUN_TEST(test_hooks_registered_guard_prevents_double_register);
+    RUN_TEST(test_open_listener_binds_named_candidate_port);
+    RUN_TEST(test_open_listener_matches_unnamed_candidate_by_hostname);
+    RUN_TEST(test_open_listener_refuses_when_name_not_in_peers);
+    RUN_TEST(test_open_listener_ignores_hostname_of_named_candidate);
 }