Define one bounded channel description encoding for signing and verification

src/chat/chat_channel.c

@@ -32,30 +32,27 @@
 #include <openssl/sha.h>
 #include <openssl/evp.h>
 #include <openssl/rand.h>
+#include <errno.h>
+#include <stdlib.h>
 
-/* ─── Ed25519 подпись join-сообщения ─── */
-
-static int channel_sign_join(const uint8_t* ch_x25519, const uint8_t* ch_ed25519,
-                              uint64_t node_id, const uint8_t* node_pubkey,
-                              uint64_t join_ts, const uint8_t* ed25519_privkey,
-                              uint8_t sig_out[64])
-{
-    uint8_t msg[128];
-    int mlen = member_sync_build_join_msg(ch_x25519, ch_ed25519, node_id, node_pubkey, join_ts,
-                                          msg, (int)sizeof(msg));
-    if (mlen < 0) { memset(sig_out, 0, 64); return -1; }
-
-    EVP_PKEY* pkey = EVP_PKEY_new_raw_private_key(EVP_PKEY_ED25519, NULL,
-        ed25519_privkey, 32);
-    if (!pkey) { memset(sig_out, 0, 64); return -1; }
-    EVP_MD_CTX* mdctx = EVP_MD_CTX_new();
-    if (!mdctx) { EVP_PKEY_free(pkey); memset(sig_out, 0, 64); return -1; }
-    int ok = EVP_DigestSignInit(mdctx, NULL, NULL, NULL, pkey) == 1
-          && EVP_DigestSign(mdctx, sig_out, &(size_t){64}, msg, (size_t)mlen) == 1;
-    EVP_MD_CTX_free(mdctx);
-    EVP_PKEY_free(pkey);
-    if (!ok) memset(sig_out, 0, 64);
-    return ok ? 0 : -1;
+/* Один формат описания для создания и проверки подписи входящего JOIN/invite. */
+int chat_channel_description_data(const char* channel, const char* name, uint64_t owner,
+    const uint8_t x25519[32], const uint8_t ed25519[32], uint8_t* out, size_t capacity) {
+    if (!channel || !name || !x25519 || !ed25519 || !out) {
+        DEBUG_ERROR(DEBUG_CATEGORY_CHAT_SYNC, "channel description: missing argument"); return -1;
+    }
+    size_t channel_len = strnlen(channel, 20), name_len = strnlen(name, 256);
+    if (!channel_len || channel_len == 20 || channel[0] == '0' || strspn(channel, "0123456789") != channel_len ||
+        strtoull(channel, NULL, 10) > INT64_MAX || name_len == 256 || capacity < channel_len + name_len + 74) {
+        DEBUG_ERROR(DEBUG_CATEGORY_CHAT_SYNC, "channel description: invalid channel/name lengths=%zu/%zu capacity=%zu",
+            channel_len, name_len, capacity); return -1;
+    }
+    size_t offset = channel_len + 1; memcpy(out, channel, offset);
+    memcpy(out + offset, name, name_len + 1); offset += name_len + 1;
+    memcpy(out + offset, &owner, 8); offset += 8;
+    memcpy(out + offset, x25519, 32); offset += 32;
+    memcpy(out + offset, ed25519, 32); offset += 32;
+    return (int)offset;
 }
 
 /* ─── подготовка инфраструктуры канала (db_sync instance) ─── */

src/chat/chat_core_priv.h

@@ -20,6 +20,7 @@
 
 #define CC_ID "chat_core"
 #define CHAT_MEDIA_BACKFILL_CHANNELS 16
+#define CHAT_CHANNEL_DESCRIPTION_MAX (20 + 256 + 8 + 32 + 32)
 
 /* ── Base64 encode/decode (URL-safe, used for msg "d" field prefix) ── */
 
@@ -119,6 +120,11 @@ void sanitize_ch_id(const char* ch_id, char* out, size_t out_sz);
 void msg_table_name(const char* ch_id, char* buf, size_t sz);
 void peers_table_name(const char* ch_id, char* buf, size_t sz);
 
+/* Байты подписи описания:канонический ID+NUL,имя<=255байт+NUL,owner native-u64,X25519/Ed25519 public[32].
+ * Возвращает длину/-1;аргументы обязательны,при отказе out не меняется. Общий формат create/JOIN/invite. */
+int chat_channel_description_data(const char* channel, const char* name, uint64_t owner,
+    const uint8_t x25519[32], const uint8_t ed25519[32], uint8_t* out, size_t capacity);
+
 /* ── db_sync registry (chat_core.c) ── */
 
 struct DB_SYNC_INSTANCE* si_find(struct UTUN_INSTANCE* inst, const char* ch_id);