Add some temporary safety mechanism if too many HTTP(S) requests in progress.

Will allow tweaking in config later. This is separate from rate-limit btw,
which also still needs to be done.

include/h.h

@@ -1392,6 +1392,7 @@ extern void url_start_async(const char *url, HttpMethod http_method, const char
 extern void url_init(void);
 extern void url_cancel_handle_by_callback_data(void *ptr);
 extern EVENT(url_socket_timeout);
+extern int downloads_in_progress(void);
 /* end of url stuff */
 extern char *collapse(char *pattern);
 extern void clear_scache_hash_table(void);

src/modules/spamreport.c

@@ -320,6 +320,17 @@ int _spamreport(Client *client, const char *ip, NameValuePrioList *details, cons
 	char *url = NULL;
 	char *body = NULL;
 	NameValuePrioList *headers = NULL;
+	int num;
+
+	num = downloads_in_progress();
+	if (num > 100)
+	{
+		// TODO: throttle this error
+		unreal_log(ULOG_WARNING, "spamreport", "SPAMREPORT_TOO_MANY_CONCURRENT_REQUESTS", NULL,
+		           "Already $num_requests HTTP(S) requests in progress, new spamreport requests ignored.",
+		           log_data_integer("num_requests", num));
+		return 0;
+	}
 
 	if (!spamreport_block)
 	{

src/url_curl.c

@@ -453,3 +453,16 @@ char *urlencode(const char *s, char *wbuf, int wlen)
 	strlcpy(wbuf, ret, wlen);
 	return wbuf;
 }
+
+int downloads_in_progress(void)
+{
+	Download *d;
+	int count = 0;
+
+	/* Bit stupid to do it this slow way, can't we maintain a counter? Needs to be accurate though */
+
+	for (d = downloads; d; d = d->next);
+		count++;
+
+	return count;
+}

src/url_unreal.c

@@ -1226,3 +1226,16 @@ char *urlencode(const char *s, char *wbuf, int wlen)
 
 	return wbuf;
 }
+
+int downloads_in_progress(void)
+{
+	Download *d;
+	int count = 0;
+
+	/* Bit stupid to do it this slow way, can't we maintain a counter? Needs to be accurate though */
+
+	for (d = downloads; d; d = d->next);
+		count++;
+
+	return count;
+}