fix: preserve 16-bit pid for RPC handshake wire compatibility

- Keep pid as unsigned short in process_id (Telegram DC expects 32-byte packet)
- Remove assert for pid>65535, use implicit truncation instead
- Revert tl-parse memcpy to 12 bytes (was sizeof for 32-bit pid)

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: root

common/pid.c

@@ -38,7 +38,8 @@ npid_t PID;
 
 void init_common_PID (void) {
   if (!PID.pid) {
-    PID.pid = (unsigned) getpid ();
+    int p = getpid ();
+    PID.pid = p;  /* implicit truncate to 16-bit; removed assert for pid>65535 */
   }
   if (!PID.utime) {
     PID.utime = time (0);
@@ -78,8 +79,8 @@ int process_id_is_newer (struct process_id *a, struct process_id *b) {
   assert (!memcmp (a, b, 6));
   if (a->utime < b->utime) { return 0; }
   if (a->utime > b->utime) { return 1; }
-  unsigned x = (a->pid - b->pid) & 0x7fffffff;
-  if (x && x <= 0x3fffffff) { return 1; }
+  int x = (a->pid - b->pid) & 0x7fff;
+  if (x && x <= 0x3fff) { return 1; }
   return 0;
 }
 

common/pid.h

@@ -29,14 +29,14 @@
 struct process_id {
   unsigned ip;
   short port;
-  unsigned pid;  /* was unsigned short; getpid() returns 32-bit on modern systems */
+  unsigned short pid;
   int utime;
 };
 
 struct process_id_ext {
   unsigned ip;
   short port;
-  unsigned pid;
+  unsigned short pid;
   int utime;
   int actor_id;
 };

common/tl-parse.c

@@ -770,7 +770,7 @@ static inline int __tl_store_init (struct tl_out_state *tlio_out, void *out, voi
 
 int tls_init_raw_msg (struct tl_out_state *tlio_out, struct process_id *pid, long long qid) {
   if (pid) {
-    memcpy (&tlio_out->out_pid_buf, pid, sizeof (struct process_id));
+    memcpy (&tlio_out->out_pid_buf, pid, 12);
     TL_OUT_PID = &tlio_out->out_pid_buf;
   } else {
     TL_OUT_PID = 0;