urldata: make maxconnects a 32 bit value

"2^32 idle connections ought to be enough for anybody"

Closes #12375

lib/conncache.c

@@ -379,15 +379,12 @@ conncache_find_first_connection(struct conncache *connc)
 bool Curl_conncache_return_conn(struct Curl_easy *data,
                                 struct connectdata *conn)
 {
-  /* data->multi->maxconnects can be negative, deal with it. */
-  size_t maxconnects =
-    (data->multi->maxconnects < 0) ? data->multi->num_easy * 4:
-    data->multi->maxconnects;
+  unsigned int maxconnects = !data->multi->maxconnects ?
+    data->multi->num_easy * 4: data->multi->maxconnects;
   struct connectdata *conn_candidate = NULL;
 
   conn->lastused = Curl_now(); /* it was used up until now */
-  if(maxconnects > 0 &&
-     Curl_conncache_size(data) > maxconnects) {
+  if(maxconnects && Curl_conncache_size(data) > maxconnects) {
     infof(data, "Connection cache is full, closing the oldest one");
 
     conn_candidate = Curl_conncache_extract_oldest(data);

lib/easy.c

@@ -744,7 +744,7 @@ static CURLcode easy_perform(struct Curl_easy *data, bool events)
     return CURLE_RECURSIVE_API_CALL;
 
   /* Copy the MAXCONNECTS option to the multi handle */
-  curl_multi_setopt(multi, CURLMOPT_MAXCONNECTS, data->set.maxconnects);
+  curl_multi_setopt(multi, CURLMOPT_MAXCONNECTS, (long)data->set.maxconnects);
 
   mcode = curl_multi_add_handle(multi, data);
   if(mcode) {

lib/multi.c

@@ -396,9 +396,6 @@ struct Curl_multi *Curl_multi_handle(int hashsize, /* socket hash */
   Curl_llist_init(&multi->msgsent, NULL);
 
   multi->multiplexing = TRUE;
-
-  /* -1 means it not set by user, use the default value */
-  multi->maxconnects = -1;
   multi->max_concurrent_streams = 100;
 
 #ifdef USE_WINSOCK
@@ -3239,6 +3236,7 @@ CURLMcode curl_multi_setopt(struct Curl_multi *multi,
 {
   CURLMcode res = CURLM_OK;
   va_list param;
+  unsigned long uarg;
 
   if(!GOOD_MULTI_HANDLE(multi))
     return CURLM_BAD_HANDLE;
@@ -3271,7 +3269,9 @@ CURLMcode curl_multi_setopt(struct Curl_multi *multi,
     multi->timer_userp = va_arg(param, void *);
     break;
   case CURLMOPT_MAXCONNECTS:
-    multi->maxconnects = va_arg(param, long);
+    uarg = va_arg(param, unsigned long);
+    if(uarg <= UINT_MAX)
+      multi->maxconnects = (unsigned int)uarg;
     break;
   case CURLMOPT_MAX_HOST_CONNECTIONS:
     multi->max_host_connections = va_arg(param, long);
@@ -3725,7 +3725,7 @@ struct Curl_easy **curl_multi_get_handles(struct Curl_multi *multi)
   struct Curl_easy **a = malloc(sizeof(struct Curl_easy *) *
                                 (multi->num_easy + 1));
   if(a) {
-    int i = 0;
+    unsigned int i = 0;
     struct Curl_easy *e = multi->easyp;
     while(e) {
       DEBUGASSERT(i < multi->num_easy);

lib/multihandle.h

@@ -93,9 +93,9 @@ struct Curl_multi {
   struct Curl_easy *easyp;
   struct Curl_easy *easylp; /* last node */
 
-  int num_easy; /* amount of entries in the linked list above. */
-  int num_alive; /* amount of easy handles that are added but have not yet
-                    reached COMPLETE state */
+  unsigned int num_easy; /* amount of entries in the linked list above. */
+  unsigned int num_alive; /* amount of easy handles that are added but have
+                             not yet reached COMPLETE state */
 
   struct Curl_llist msglist; /* a list of messages from completed transfers */
 
@@ -136,9 +136,6 @@ struct Curl_multi {
   /* Shared connection cache (bundles)*/
   struct conncache conn_cache;
 
-  long maxconnects; /* if >0, a fixed limit of the maximum number of entries
-                       we're allowed to grow the connection cache to */
-
   long max_host_connections; /* if >0, a fixed limit of the maximum number
                                 of connections per host */
 
@@ -150,8 +147,6 @@ struct Curl_multi {
   void *timer_userp;
   struct curltime timer_lastcall; /* the fixed time for the timeout for the
                                     previous callback */
-  unsigned int max_concurrent_streams;
-
 #ifdef USE_WINSOCK
   WSAEVENT wsa_event; /* winsock event used for waits */
 #else
@@ -160,6 +155,10 @@ struct Curl_multi {
                                    0 is used for read, 1 is used for write */
 #endif
 #endif
+  unsigned int max_concurrent_streams;
+  unsigned int maxconnects; /* if >0, a fixed limit of the maximum number of
+                               entries we're allowed to grow the connection
+                               cache to */
 #define IPV6_UNKNOWN 0
 #define IPV6_DEAD    1
 #define IPV6_WORKS   2

lib/setopt.c

@@ -262,10 +262,10 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
      * Set the absolute number of maximum simultaneous alive connection that
      * libcurl is allowed to have.
      */
-    arg = va_arg(param, long);
-    if(arg < 0)
+    uarg = va_arg(param, unsigned long);
+    if(uarg > UINT_MAX)
       return CURLE_BAD_FUNCTION_ARGUMENT;
-    data->set.maxconnects = arg;
+    data->set.maxconnects = (unsigned int)uarg;
     break;
   case CURLOPT_FORBID_REUSE:
     /*

lib/urldata.h

@@ -1824,8 +1824,6 @@ struct UserDefined {
   int tcp_keepidle;     /* seconds in idle before sending keepalive probe */
   int tcp_keepintvl;    /* seconds between TCP keepalive probes */
 
-  size_t maxconnects;    /* Max idle connections in the connection cache */
-
   long expect_100_timeout; /* in milliseconds */
 #if defined(USE_HTTP2) || defined(USE_HTTP3)
   struct Curl_data_priority priority;
@@ -1850,6 +1848,7 @@ struct UserDefined {
   BIT(mail_rcpt_allowfails); /* allow RCPT TO command to fail for some
                                 recipients */
 #endif
+  unsigned int maxconnects; /* Max idle connections in the connection cache */
   unsigned char use_ssl;   /* if AUTH TLS is to be attempted etc, for FTP or
                               IMAP or POP3 or others! (type: curl_usessl)*/
   unsigned char connect_only; /* make connection/request, then let