netops: add method to return default http port for a connection

Constant strings and logic for HTTP(S) default ports were starting to be
spread throughout netops.c.  Instead of duplicating this again to
determine if a Host header should include the port, move the default
port constants and logic into an internal method in netops.{c,h}.

src/netops.c

@@ -119,6 +119,15 @@ int gitno__match_host(const char *pattern, const char *host)
 	return -1;
 }
 
+static const char *default_port_http = "80";
+static const char *default_port_https = "443";
+
+const char *gitno__default_port(
+	gitno_connection_data *data)
+{
+	return data->use_ssl ? default_port_https : default_port_http;
+}
+
 static const char *prefix_http = "http://";
 static const char *prefix_https = "https://";
 
@@ -141,7 +150,7 @@ int gitno_connection_data_from_url(
 
 	if (!git__prefixcmp(url, prefix_http)) {
 		path_search_start = url + strlen(prefix_http);
-		default_port = "80";
+		default_port = default_port_http;
 
 		if (data->use_ssl) {
 			giterr_set(GITERR_NET, "redirect from HTTPS to HTTP is not allowed");
@@ -149,10 +158,10 @@ int gitno_connection_data_from_url(
 		}
 	} else if (!git__prefixcmp(url, prefix_https)) {
 		path_search_start = url + strlen(prefix_https);
-		default_port = "443";
+		default_port = default_port_https;
 		data->use_ssl = true;
 	} else if (url[0] == '/')
-		default_port = data->use_ssl ? "443" : "80";
+		default_port = gitno__default_port(data);
 
 	if (!default_port) {
 		giterr_set(GITERR_NET, "unrecognized URL prefix");

src/netops.h

@@ -96,4 +96,6 @@ int gitno_extract_url_parts(
 		const char *url,
 		const char *default_port);
 
+const char *gitno__default_port(gitno_connection_data *data);
+
 #endif