ip4tos.c

00001 /*
00002  * Copyright (c) 2014-2018 ARM Limited. All rights reserved.
00003  * SPDX-License-Identifier: Apache-2.0
00004  * Licensed under the Apache License, Version 2.0 (the License); you may
00005  * not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  * http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00012  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #include <stdio.h>
00017 #include <string.h>
00018 #include "common_functions.h"
00019 #include "ip4string.h"
00020 
00021 static void ipv4_itoa(char *string, uint8_t byte);
00022 
00023 /**
00024  * Print binary IPv4 address to a string.
00025  * String must contain enough room for full address, 16 bytes exact.
00026  * \param addr IPv4 address.
00027  * \p buffer to write string to.
00028  */
00029 uint_fast8_t ip4tos(const void *ip4addr, char *p)
00030 {
00031     uint_fast8_t outputPos = 0;
00032     const uint8_t *byteArray = ip4addr;
00033 
00034     for (uint_fast8_t component = 0; component < 4; ++component) {
00035         //Convert the byte to string
00036         ipv4_itoa(&p[outputPos], byteArray[component]);
00037 
00038         //Move outputPos to the end of the string
00039         while (p[outputPos] != '\0') {
00040             outputPos += 1;
00041         }
00042 
00043         //Append a dot if this is not the last digit
00044         if (component < 3) {
00045             p[outputPos++] = '.';
00046         }
00047     }
00048 
00049     // Return length of generated string, excluding the terminating null character
00050     return outputPos;
00051 }
00052 
00053 static void ipv4_itoa(char *string, uint8_t byte)
00054 {
00055     char *baseString = string;
00056 
00057     //Write the digits to the buffer from the least significant to the most
00058     //  This is the incorrect order but we will swap later
00059     do {
00060         *string++ = '0' + byte % 10;
00061         byte /= 10;
00062     } while (byte);
00063 
00064     //We put the final \0, then go back one step on the last digit for the swap
00065     *string-- = '\0';
00066 
00067     //We now swap the digits
00068     while (baseString < string) {
00069         uint8_t tmp = *string;
00070         *string-- = *baseString;
00071         *baseString++ = tmp;
00072     }
00073 }