1 /*
2  * Copyright (c) 1999 Kungliga Tekniska Högskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *      This product includes software developed by the Kungliga Tekniska
20  *      Högskolan and its contributors.
21  *
22  * 4. Neither the name of the Institute nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 #ifdef HAVE_CONFIG_H
40 #include <config.h>
41 #endif
42 
43 #include "netdissect-stdinc.h"
44 #include "addrtostr.h"
45 
46 #include <stdio.h>
47 #include <string.h>
48 
49 /*
50  *
51  */
52 
53 #ifndef IN6ADDRSZ
54 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
55 #endif
56 
57 #ifndef INT16SZ
58 #define INT16SZ     2    /* word size */
59 #endif
60 
61 const char *
addrtostr(const void * src,char * dst,size_t size)62 addrtostr (const void *src, char *dst, size_t size)
63 {
64     const u_char *srcaddr = (const u_char *)src;
65     const char digits[] = "0123456789";
66     int i;
67     const char *orig_dst = dst;
68 
69     if (size < INET_ADDRSTRLEN) {
70 	errno = ENOSPC;
71 	return NULL;
72     }
73     for (i = 0; i < 4; ++i) {
74     	int n = *srcaddr++;
75 	int non_zerop = 0;
76 
77 	if (non_zerop || n / 100 > 0) {
78 	    *dst++ = digits[n / 100];
79 	    n %= 100;
80 	    non_zerop = 1;
81 	}
82 	if (non_zerop || n / 10 > 0) {
83 	    *dst++ = digits[n / 10];
84 	    n %= 10;
85 	    non_zerop = 1;
86 	}
87 	*dst++ = digits[n];
88 	if (i != 3)
89 	    *dst++ = '.';
90     }
91     *dst++ = '\0';
92     return orig_dst;
93 }
94 
95 /*
96  * Convert IPv6 binary address into presentation (printable) format.
97  */
98 const char *
addrtostr6(const void * src,char * dst,size_t size)99 addrtostr6 (const void *src, char *dst, size_t size)
100 {
101   /*
102    * Note that int32_t and int16_t need only be "at least" large enough
103    * to contain a value of the specified size.  On some systems, like
104    * Crays, there is no such thing as an integer variable with 16 bits.
105    * Keep this in mind if you think this function should have been coded
106    * to use pointer overlays.  All the world's not a VAX.
107    */
108   const u_char *srcaddr = (const u_char *)src;
109   char *dp;
110   size_t space_left, added_space;
111   int snprintfed;
112   struct {
113     int base;
114     int len;
115   } best, cur;
116   uint16_t words [IN6ADDRSZ / INT16SZ];
117   int  i;
118 
119   /* Preprocess:
120    *  Copy the input (bytewise) array into a wordwise array.
121    *  Find the longest run of 0x00's in src[] for :: shorthanding.
122    */
123   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
124       words[i] = (srcaddr[2*i] << 8) | srcaddr[2*i + 1];
125 
126   best.len = 0;
127   best.base = -1;
128   cur.len = 0;
129   cur.base  = -1;
130   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
131   {
132     if (words[i] == 0)
133     {
134       if (cur.base == -1)
135            cur.base = i, cur.len = 1;
136       else cur.len++;
137     }
138     else if (cur.base != -1)
139     {
140       if (best.base == -1 || cur.len > best.len)
141          best = cur;
142       cur.base = -1;
143     }
144   }
145   if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
146      best = cur;
147   if (best.base != -1 && best.len < 2)
148      best.base = -1;
149 
150   /* Format the result.
151    */
152   dp = dst;
153   space_left = size;
154 #define APPEND_CHAR(c) \
155     { \
156         if (space_left == 0) { \
157             errno = ENOSPC; \
158             return (NULL); \
159         } \
160         *dp++ = c; \
161         space_left--; \
162     }
163   for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
164   {
165     /* Are we inside the best run of 0x00's?
166      */
167     if (best.base != -1 && i >= best.base && i < (best.base + best.len))
168     {
169       if (i == best.base)
170       	 APPEND_CHAR(':');
171       continue;
172     }
173 
174     /* Are we following an initial run of 0x00s or any real hex?
175      */
176     if (i != 0)
177        APPEND_CHAR(':');
178 
179     /* Is this address an encapsulated IPv4?
180      */
181     if (i == 6 && best.base == 0 &&
182         (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
183     {
184       if (!addrtostr(srcaddr+12, dp, space_left))
185       {
186         errno = ENOSPC;
187         return (NULL);
188       }
189       added_space = strlen(dp);
190       dp += added_space;
191       space_left -= added_space;
192       break;
193     }
194     snprintfed = snprintf (dp, space_left, "%x", words[i]);
195     if (snprintfed < 0)
196         return (NULL);
197     if ((size_t) snprintfed >= space_left)
198     {
199         errno = ENOSPC;
200         return (NULL);
201     }
202     dp += snprintfed;
203     space_left -= snprintfed;
204   }
205 
206   /* Was it a trailing run of 0x00's?
207    */
208   if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
209      APPEND_CHAR(':');
210   APPEND_CHAR('\0');
211 
212   return (dst);
213 }
214