acc: use acc.time_mode to save cdrs in gmtime

acc.time_mode modparam allows saving acc transactions time field using
the output of gmtime() when it is set to 4.

This commit aims to reuse this modparam for cdr entries, storing start_time
and end_time in gmtime if time_mode is 4.

Fixes kamailio#1358

src/modules/acc/acc_cdr.c

@@ -64,6 +64,7 @@
 
 #define TIME_STR_BUFFER_SIZE 20
 #define TIME_BUFFER_LENGTH 256
+#define TIME_STRING_FORMAT "%Y-%m-%d %H:%M:%S"
 
 struct dlg_binds dlgb;
 struct acc_extra* cdr_extra = NULL;
@@ -141,6 +142,8 @@ static int db_write_cdr( struct dlg_cell* dialog,
 	long long_val;
 	double double_val;
 	char * end;
+	struct tm *t;
+	char cdr_time_format_buf[MAX_CDR_CORE][TIME_STR_BUFFER_SIZE];
 
 	if(acc_cdrs_table.len<=0)
 		return 0;
@@ -182,13 +185,24 @@ static int db_write_cdr( struct dlg_cell* dialog,
 				VAL_STR(db_cdr_vals+i) = cdr_value_array[i];
 				break;
 			case TYPE_DATE:
-				VAL_TYPE(db_cdr_vals+i)=DB1_DATETIME;
 				VAL_NULL(db_cdr_vals+i)=0;
 				if(string2time(&cdr_value_array[i], &timeval_val) < 0) {
 					LM_ERR("failed to convert string to timeval.\n");
 					goto error;
 				}
-				VAL_TIME(db_cdr_vals+i) = timeval_val.tv_sec;
+				if (acc_time_mode==4) {
+					VAL_TYPE(db_cdr_vals+i)=DB1_STR;
+					t = gmtime(&timeval_val.tv_sec);
+					/* Convert time_t structure to format accepted by the database */
+					if (strftime(cdr_time_format_buf[i], TIME_STR_BUFFER_SIZE, TIME_STRING_FORMAT, t) <= 0) {
+						cdr_time_format_buf[i][0] = '\0';
+					}
+
+					VAL_STR(db_cdr_vals+i) = (str){cdr_time_format_buf[i], TIME_STR_BUFFER_SIZE-1};
+				} else {
+					VAL_TYPE(db_cdr_vals+i)=DB1_DATETIME;
+					VAL_TIME(db_cdr_vals+i) = timeval_val.tv_sec;
+				}
 				break;
 			case TYPE_DOUBLE:
 				VAL_TYPE(db_cdr_vals+i)=DB1_DOUBLE;