curl: add an option to fetch bound to a local source address

src/libstrongswan/fetcher/fetcher.h

@@ -89,6 +89,12 @@ enum fetcher_option_t {
 	 */
 	FETCH_CALLBACK,
 
+	/**
+	 * Source IP address to bind for a fetch.
+	 * Additional argument is a host_t*, which may be NULL.
+	 */
+	FETCH_SOURCEIP,
+
 	/**
 	 * end of fetching options
 	 */

src/libstrongswan/fetcher/fetcher_manager.c

@@ -73,6 +73,7 @@ METHOD(fetcher_manager_t, fetch, status_t,
 		fetcher_option_t opt;
 		fetcher_t *fetcher;
 		bool good = TRUE;
+		host_t *host;
 		va_list args;
 
 		/* check URL support of fetcher */
@@ -112,6 +113,13 @@ METHOD(fetcher_manager_t, fetch, status_t,
 					good = fetcher->set_option(fetcher, opt,
 											va_arg(args, fetcher_callback_t));
 					continue;
+				case FETCH_SOURCEIP:
+					host = va_arg(args, host_t*);
+					if (host && !host->is_anyaddr(host))
+					{
+						good = fetcher->set_option(fetcher, opt, host);
+					}
+					continue;
 				case FETCH_END:
 					break;
 			}

src/libstrongswan/plugins/curl/curl_fetcher.c

@@ -177,6 +177,15 @@ METHOD(fetcher_t, set_option, bool,
 			this->cb = va_arg(args, fetcher_callback_t);
 			break;
 		}
+		case FETCH_SOURCEIP:
+		{
+			char buf[64];
+
+			snprintf(buf, sizeof(buf), "%H", va_arg(args, host_t*));
+			supported = curl_easy_setopt(this->curl, CURLOPT_INTERFACE,
+										 buf) == CURLE_OK;
+			break;
+		}
 		default:
 			supported = FALSE;
 			break;