db_sync: fix dh_match premature sync complete — send tail when mc > tp+1

Root cause: db_handle_init_resp marked sync_state=2 when my_dh==peer_dh
without checking that all my records fit in the confirmed prefix.
If mc > tp+1 (I have records beyond the common prefix), the tail was
never sent — lost records.

Fix:
- Remove special-case 'sc==0 && my_dh==peer_dh' (redundant, same bug)
- In general dh_match: if mc > tp+1, send remaining records [tp+1,mc-1]
  using the same inline loop pattern as 'peer empty' branch

Test: 3 phases covering all dh_match paths:
- Phase 1: B empty+late instance → dh_match at tp=0 (sc=0) → tail-send 49
- Phase 2: A=80 B=50 → dh_match at tp=49 (sc>0, sparse) → tail-send 30
- Phase 3: fresh instances → peer empty → send all 30

src/db_sync.c

@@ -738,19 +738,6 @@ static void db_handle_init_resp(struct DB_SYNC_INSTANCE* si,
     uint64_t my_dh = 0;
     db_datahash_at(si, tp, &my_dh);
 
-    if (sc == 0 && my_dh == peer_dh) {
-        struct SI_PEER* sp = si_peer_find(si, src);
-        uint32_t mc = db_count(si);
-        if (sp) {
-            sp->synced_pos = tp;
-            sp->sync_state = 2;
-        }
-        DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC,
-                   "sync complete with %016llx tp=%u my_mc=%u",
-                   (unsigned long long)src, tp, mc);
-        return;
-    }
-
     if (peer_dh == 0 && sc == 0) {
         uint32_t mc = db_count(si);
         uint32_t batches = (mc + DB_SEND_DATA_MAX - 1) / DB_SEND_DATA_MAX;
@@ -821,12 +808,62 @@ static void db_handle_init_resp(struct DB_SYNC_INSTANCE* si,
     if (my_dh == peer_dh) {
         uint32_t mc = db_count(si);
         struct SI_PEER* sp = si_peer_find(si, src);
+        uint32_t tail = tp + 1;
+        if (mc > tail) {
+            DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC,
+                       "dh match at tp=%u my_mc=%u — sending tail [%u,%u) to %016llx",
+                       tp, mc, tail, mc, (unsigned long long)src);
+            uint32_t sent = tail;
+            while (sent < mc) {
+                uint32_t b = mc - sent;
+                if (b > DB_SEND_DATA_MAX) b = DB_SEND_DATA_MAX;
+                uint8_t sdbuf[8192];
+                uint32_t off = 0;
+                sdbuf[off++] = DB_MSG_SEND_DATA;
+                memcpy(sdbuf + off, &sent, 4); off += 4;
+                uint16_t rc = 0;
+                uint16_t* rcp = (uint16_t*)(sdbuf + off); off += 2;
+                sqlite3_stmt* stmt;
+                si_prep(si, &stmt,
+                        "SELECT id,timestamp,datahash,data,author_signature"
+                        " FROM \"%s\" ORDER BY timestamp,datahash"
+                        " LIMIT ? OFFSET ?");
+                sqlite3_bind_int64(stmt, 1, (sqlite3_int64)b);
+                sqlite3_bind_int64(stmt, 2, (sqlite3_int64)sent);
+                while (sqlite3_step(stmt) == SQLITE_ROW) {
+                    uint64_t rid = (uint64_t)sqlite3_column_int64(stmt, 0);
+                    uint64_t rts = (uint64_t)sqlite3_column_int64(stmt, 1);
+                    uint64_t rdh = (uint64_t)sqlite3_column_int64(stmt, 2);
+                    const uint8_t* rd = (const uint8_t*)sqlite3_column_blob(stmt, 3);
+                    uint32_t rdl = (uint32_t)sqlite3_column_bytes(stmt, 3);
+                    if (!rd) rdl = 0;
+                    const uint8_t* rsig = (const uint8_t*)sqlite3_column_blob(stmt, 4);
+                    int rsl = sqlite3_column_bytes(stmt, 4);
+                    if (!rsig) rsl = 0;
+                    int rec_sz = 28 + rdl + 1 + rsl;
+                    if (off + rec_sz > (int)sizeof(sdbuf)) break;
+                    memcpy(sdbuf + off, &rid, 8); off += 8;
+                    memcpy(sdbuf + off, &rts, 8); off += 8;
+                    memcpy(sdbuf + off, &rdh, 8); off += 8;
+                    memcpy(sdbuf + off, &rdl, 4); off += 4;
+                    if (rdl > 0) { memcpy(sdbuf + off, rd, rdl); off += rdl; }
+                    sdbuf[off++] = (uint8_t)rsl;
+                    if (rsl > 0) { memcpy(sdbuf + off, rsig, rsl); off += rsl; }
+                    rc++;
+                }
+                sqlite3_finalize(stmt);
+                *rcp = rc;
+                sent += rc;
+                db_sync_send(si, src, sdbuf, off);
+                if (rc == 0) break;
+            }
+        }
         if (sp) {
             sp->synced_pos = tp;
             sp->sync_state = 2;
         }
         DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC,
-                   "dh match with %016llx at tp=%u my_mc=%u",
+                   "sync complete with %016llx tp=%u my_mc=%u",
                    (unsigned long long)src, tp, mc);
         return;
     }

tests/test_db_sync.c

@@ -1,4 +1,4 @@
-// test_db_sync.c — всестороннее тестирование модуля db_sync
+// test_db_sync.c — тестирование db_sync: dh_match tail-send и peer empty
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -27,19 +27,16 @@
 #include "../lib/debug_config.h"
 #include "../lib/mem.h"
 
-#define TEST_TIMEOUT_TB  300000  // 30s total
-#define PHASE_TIMEOUT_TB 150000  // 15s per phase
+#define TEST_TIMEOUT_TB  600000  // 60s
+#define PHASE_TIMEOUT_TB 250000  // 25s
 #define POLL_INTERVAL_MS 5
 
-#define NODE_ID_A 0xAAAAAAAAAAAAAAAAULL
-#define NODE_ID_B 0xBBBBBBBBBBBBBBBBULL
-
 static struct UTUN_INSTANCE* inst_a = NULL;
 static struct UTUN_INSTANCE* inst_b = NULL;
 static struct DB_SYNC_INSTANCE* si_a = NULL;
 static struct DB_SYNC_INSTANCE* si_b = NULL;
 static struct UASYNC* ua = NULL;
-static int test_phase = 0;  // 0=running, 1=success, 2=failure
+static int test_phase = 0;
 static void* timeout_id = NULL;
 
 static char temp_dir[] = "/tmp/utun_dbsync_XXXXXX";
@@ -47,8 +44,7 @@ static char config_a[256], config_b[256];
 static int port_a_srv, port_b_srv;
 
 static int write_file(const char* path, const char* fmt, ...) {
-    va_list ap;
-    FILE* f = fopen(path, "w");
+    va_list ap; FILE* f = fopen(path, "w");
     if (!f) return -1;
     va_start(ap, fmt); vfprintf(f, fmt, ap); va_end(ap);
     fclose(f); return 0;
@@ -66,52 +62,24 @@ static int create_temp_configs(void) {
     port_a_srv = base; port_b_srv = base + 1;
     snprintf(config_a, sizeof(config_a), "%s/a.conf", temp_dir);
     snprintf(config_b, sizeof(config_b), "%s/b.conf", temp_dir);
-
-    // Create SQLite db directories (parent dir for sync file)
     char db_path[320];
     snprintf(db_path, sizeof(db_path), "%s/db_a", temp_dir); utun_mkdir(db_path, 0755);
     snprintf(db_path, sizeof(db_path), "%s/db_b", temp_dir); utun_mkdir(db_path, 0755);
 
     if (write_file(config_a,
-        "[global]\n"
-        "my_node_id=0xAAAAAAAAAAAAAAAA\n"
-        "tun_ip=10.200.0.1/24\n"
-        "tun_ifname=tun200\n"
-        "keepalive_adaptive=0\n"
-        "db_path=%s/db_a\n"
-        "db_sync_enabled=1\n"
-        "\n"
-        "[server: srv_a]\n"
-        "addr=127.0.0.1:%d\n"
-        "type=public\n"
-        "\n"
-        "[allowed_keys]\n"
-        "allow_all=1\n",
-        temp_dir, port_a_srv) != 0) return -1;
+        "[global]\nmy_node_id=0xAAAAAAAAAAAAAAAA\ntun_ip=10.200.0.1/24\n"
+        "tun_ifname=tun200\nkeepalive_adaptive=0\ndb_path=%s/db_a\ndb_sync_enabled=1\n\n"
+        "[server: srv_a]\naddr=127.0.0.1:%d\ntype=public\n\n"
+        "[allowed_keys]\nallow_all=1\n", temp_dir, port_a_srv) != 0) return -1;
     if (config_ensure_keys_and_node_id(config_a) != 0) return -1;
-    char* pub_a = get_pubkey(config_a);
-    if (!pub_a) return -1;
+    char* pub_a = get_pubkey(config_a); if (!pub_a) return -1;
 
     if (write_file(config_b,
-        "[global]\n"
-        "my_node_id=0xBBBBBBBBBBBBBBBB\n"
-        "tun_ip=10.200.0.2/24\n"
-        "tun_ifname=tun201\n"
-        "keepalive_adaptive=0\n"
-        "db_path=%s/db_b\n"
-        "db_sync_enabled=1\n"
-        "\n"
-        "[server: srv_b]\n"
-        "addr=127.0.0.1:%d\n"
-        "type=public\n"
-        "\n"
-        "[client: to_a]\n"
-        "keepalive=1\n"
-        "peer_public_key=%s\n"
-        "link=srv_b:127.0.0.1:%d\n"
-        "\n"
-        "[allowed_keys]\n"
-        "allow_all=1\n",
+        "[global]\nmy_node_id=0xBBBBBBBBBBBBBBBB\ntun_ip=10.200.0.2/24\n"
+        "tun_ifname=tun201\nkeepalive_adaptive=0\ndb_path=%s/db_b\ndb_sync_enabled=1\n\n"
+        "[server: srv_b]\naddr=127.0.0.1:%d\ntype=public\n\n"
+        "[client: to_a]\nkeepalive=1\npeer_public_key=%s\nlink=srv_b:127.0.0.1:%d\n\n"
+        "[allowed_keys]\nallow_all=1\n",
         temp_dir, port_b_srv, pub_a, port_a_srv) != 0) { free(pub_a); return -1; }
     free(pub_a);
     if (config_ensure_keys_and_node_id(config_b) != 0) return -1;
@@ -143,103 +111,112 @@ static int wait_for(const char* desc, int (*cond)(void), int timeout_tb) {
     return 0;
 }
 
-static void sleep_tb(int tb) {
-    uint64_t end = get_time_tb() + (uint64_t)tb;
-    while (get_time_tb() < end && test_phase == 0) uasync_poll(ua, POLL_INTERVAL_MS);
-}
-
-// ---- Condition functions ----
 static int cond_links_init(void) {
     if (!inst_a || !inst_b) return 0;
-    struct ll_entry* entry = inst_a->connections->head;
-    while (entry) { struct conn_queue_entry* ce = (struct conn_queue_entry*)entry->data;
-        struct ETCP_CONN* ca = ce->conn;
-        struct ETCP_LINK* l = ca->links; while (l) { if (l->initialized) return 1; l = l->next; }
-        entry = entry->next; }
+    struct ll_entry* e = inst_a->connections->head;
+    while (e) { struct conn_queue_entry* ce = (struct conn_queue_entry*)e->data;
+        struct ETCP_LINK* l = ce->conn->links; while (l) { if (l->initialized) return 1; l = l->next; }
+        e = e->next; }
     return 0;
 }
-
-static int cond_count_a(uint32_t expected) {
-    if (!si_a) return 0;
-    return db_sync_count(si_a) == expected;
-}
-static int cond_count_b(uint32_t expected) {
-    if (!si_b) return 0;
-    return db_sync_count(si_b) == expected;
-}
-static uint32_t count_a_target, count_b_target;
-static int _cond_count_a(void) { return cond_count_a(count_a_target); }
-static int _cond_count_b(void) { return cond_count_b(count_b_target); }
+static uint32_t ca_target, cb_target;
+static int _cond_ca(void) { return si_a && db_sync_count(si_a) == ca_target; }
+static int _cond_cb(void) { return si_b && db_sync_count(si_b) == cb_target; }
 
 static int insert_many(struct DB_SYNC_INSTANCE* si, int start, int count) {
     char buf[128];
     for (int i = start; i < start + count && test_phase == 0; i++) {
-        snprintf(buf, sizeof(buf), "{\"idx\":%d,\"val\":\"data_%d\",\"pad\":\"%s\"}", i, i,
+        snprintf(buf, sizeof(buf), "{\"idx\":%d,\"val\":\"data_%d\",\"pad\":\"%.50s\"}", i, i,
                  "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
-        int ret = db_sync_insert(si, buf);
-        if (ret < 0) { fprintf(stderr, "insert_many failed at %d ret=%d\n", i, ret); return -1; }
+        if (db_sync_insert(si, buf) < 0) { fprintf(stderr,"insert_many fail %d\n", i); return -1; }
     }
     return 0;
 }
 
-static int insert_many_batch(struct DB_SYNC_INSTANCE* si, int start, int count) {
-    char buf[256];
-    for (int i = start; i < start + count && test_phase == 0; i++) {
-        snprintf(buf, sizeof(buf), "{\"n\":%d,\"text\":\"record_number_%d_abcdefghijklmnopqrstuvwxyz\"}", i, i);
-        db_sync_insert(si, buf);
-    }
-    return 0;
+static void remove_si(struct DB_SYNC_INSTANCE** psi) {
+    if (*psi) { db_sync_instance_remove(*psi); *psi = NULL; }
 }
 
 // ---- Main test ----
 int main(void) {
     printf("=== test_db_sync ===\n");
 
-    debug_config_init();
-    debug_set_level(DEBUG_LEVEL_ERROR);  // quiet
-
+    debug_config_init(); debug_set_level(DEBUG_LEVEL_ERROR);
     if (create_temp_configs() != 0) { fprintf(stderr, "config creation failed\n"); return 1; }
 
     utun_instance_set_tun_init_enabled(0);
     ua = uasync_create();
-    if (!ua) { fprintf(stderr, "uasync_create failed\n"); cleanup_temp_configs(); return 1; }
+    if (!ua) { cleanup_temp_configs(); return 1; }
 
     inst_a = utun_instance_create(ua, config_a);
     inst_b = utun_instance_create(ua, config_b);
-    if (!inst_a || !inst_b) { fprintf(stderr, "instance create failed\n"); cleanup_temp_configs(); return 1; }
-
-    if (utun_instance_init(inst_a) != 0 || utun_instance_init(inst_b) != 0) {
-        fprintf(stderr, "instance init failed\n"); cleanup_temp_configs(); return 1;
+    if (!inst_a || !inst_b || utun_instance_init(inst_a) != 0 || utun_instance_init(inst_b) != 0) {
+        fprintf(stderr, "instance create/init failed\n"); cleanup_temp_configs(); return 1;
     }
+    timeout_id = uasync_set_timeout(ua, TEST_TIMEOUT_TB, NULL, test_timeout, "global_timeout");
+
+    // ===================================================================
+    // Phase 1: late B — A=50, B=0. B создан ПОСЛЕ conn_up (A не инициирует).
+    // Только B инициирует: divergence → REFINE → SEND_DATA(1) → SYNC_DONE
+    // mismatch → A ретраит → dh_match(tp=0,sc=0) → должен отправить хвост [1..49].
+    // ===================================================================
+    printf("Phase 1: late B — dh_match at tp=0 (sc=0) + tail-send 49 records\n");
+    if (!wait_for("links up", cond_links_init, PHASE_TIMEOUT_TB)) { test_phase=2; goto done; }
 
     si_a = db_sync_instance_add(inst_a, "test", 1);
-    si_b = db_sync_instance_add(inst_b, "test", 1);
-    if (!si_a || !si_b) { fprintf(stderr, "db_sync_instance_add failed\n"); return 1; }
+    if (!si_a || insert_many(si_a, 0, 50) != 0) { test_phase=2; goto done; }
+    if (db_sync_count(si_a) != 50) { fprintf(stderr, "FAIL: A!=50\n"); test_phase=2; goto done; }
+    printf("  A has 50 records, creating B now (B empty, A conn_up already fired)\n");
 
-    timeout_id = uasync_set_timeout(ua, TEST_TIMEOUT_TB, NULL, test_timeout, "test_timeout");
+    si_b = db_sync_instance_add(inst_b, "test", 1);
+    if (!si_b || db_sync_count(si_b) != 0) { test_phase=2; goto done; }
 
-    // ===== Phase 1: базовый CRUD =====
-    printf("Phase 1: basic CRUD...\n");
-    if (db_sync_count(si_a) != 0) { fprintf(stderr, "FAIL: initial count not 0 (got %u)\n", db_sync_count(si_a)); test_phase=2; }
+    cb_target = 50;
+    if (!wait_for("B count=50 (dh_match tp=0 tail)", _cond_cb, PHASE_TIMEOUT_TB)) { test_phase=2; goto done; }
+    printf("  Phase 1 PASS: B=%u A=%u\n", db_sync_count(si_b), db_sync_count(si_a));
 
-    if (db_sync_insert(si_a, "{\"key\":\"val1\"}") != 0) { fprintf(stderr,"FAIL: insert 1\n"); test_phase=2; }
-    if (db_sync_insert(si_a, "{\"key\":\"val2\"}") != 0) { fprintf(stderr,"FAIL: insert 2\n"); test_phase=2; }
-    if (db_sync_insert(si_a, "{\"key\":\"val3\"}") != 0) { fprintf(stderr,"FAIL: insert 3\n"); test_phase=2; }
-    if (db_sync_count(si_a) != 3) { fprintf(stderr,"FAIL: count not 3 (got %u)\n", db_sync_count(si_a)); test_phase=2; }
-    // Dedup by (timestamp,datahash): same content at different time = new record
-    if (db_sync_insert(si_a, "{\"key\":\"val4\"}") != 0) { fprintf(stderr,"FAIL: insert 4\n"); test_phase=2; }
-    if (db_sync_count(si_a) != 4) { fprintf(stderr,"FAIL: count not 4 (got %u)\n", db_sync_count(si_a)); test_phase=2; }
-    if (test_phase == 0) printf("Phase 1: PASS (count=4)\n");
+    // ===================================================================
+    // Phase 2: recreate A after adding 30 more — A=80, B=50.
+    // A инициирует: dh_match(tp=49, sc>0, sparse hashes) — должен отправить хвост [50..79].
+    // ===================================================================
+    printf("Phase 2: recreate A — dh_match at tp=49 (sc>0 sparse) + tail-send 30 records\n");
 
-    // ===== Phase 2: initial sync A↔B =====
-    printf("Phase 2: initial sync...\n");
-    if (test_phase == 0) { count_b_target = 4; if (!wait_for("B count=4", _cond_count_b, PHASE_TIMEOUT_TB)) test_phase=2; }
-    if (test_phase == 0) printf("Phase 2: PASS (B synced %u records)\n", db_sync_count(si_b));
+    if (insert_many(si_a, 50, 30) != 0) { test_phase=2; goto done; }
+    if (db_sync_count(si_a) != 80) { fprintf(stderr, "FAIL: A!=80\n"); test_phase=2; goto done; }
 
-    // ===== Cleanup =====
+    remove_si(&si_a);
+    si_a = db_sync_instance_add(inst_a, "test", 1);
+    if (!si_a || db_sync_count(si_a) != 80) { test_phase=2; goto done; }
+    printf("  A recreated (80 records), B has 50 — A will initiate with tail\n");
+
+    cb_target = 80;
+    if (!wait_for("B count=80 (dh_match tp=49 sparse)", _cond_cb, PHASE_TIMEOUT_TB)) { test_phase=2; goto done; }
+    printf("  Phase 2 PASS: B=%u A=%u\n", db_sync_count(si_b), db_sync_count(si_a));
+
+    // ===================================================================
+    // Phase 3: fresh instances, A=30, B=0, both created simultaneously.
+    // A инициирует: peer empty (peer_dh=0, sc=0) — отправляет все 30.
+    // B тоже инициирует но расходится через divergence+reinit+dh_match(tp=0) —  
+    // но A уже всё отправил, так что B и так получит через A's sync.
+    // ===================================================================
+    printf("Phase 3: fresh instances A=30 B=0, both initiate — peer empty\n");
+
+    remove_si(&si_a);
+    remove_si(&si_b);
+    si_a = db_sync_instance_add(inst_a, "test2", 2);
+    si_b = db_sync_instance_add(inst_b, "test2", 2);
+    if (!si_a || !si_b) { test_phase=2; goto done; }
+
+    if (insert_many(si_a, 0, 30) != 0 || db_sync_count(si_a) != 30) { test_phase=2; goto done; }
+
+    cb_target = 30;
+    if (!wait_for("B count=30 (peer empty)", _cond_cb, PHASE_TIMEOUT_TB)) { test_phase=2; goto done; }
+    printf("  Phase 3 PASS: B=%u A=%u\n", db_sync_count(si_b), db_sync_count(si_a));
+
+done:
+    remove_si(&si_a);
+    remove_si(&si_b);
     if (timeout_id && ua) { uasync_cancel_timeout(ua, timeout_id); timeout_id = NULL; }
-    if (si_a) { db_sync_instance_remove(si_a); si_a = NULL; }
-    if (si_b) { db_sync_instance_remove(si_b); si_b = NULL; }
     if (inst_a) { inst_a->running = 0; utun_instance_destroy(inst_a); inst_a = NULL; }
     if (inst_b) { inst_b->running = 0; utun_instance_destroy(inst_b); inst_b = NULL; }
     if (ua) { uasync_destroy(ua, 0); ua = NULL; }