1 /* $NetBSD: decodenetnum.c,v 1.7 2022/10/09 21:41:03 christos Exp $ */
2
3 /*
4 * decodenetnum - return a net number (this is crude, but careful)
5 */
6 #include <config.h>
7 #include <sys/types.h>
8 #include <ctype.h>
9 #ifdef HAVE_SYS_SOCKET_H
10 #include <sys/socket.h>
11 #endif
12 #ifdef HAVE_NETINET_IN_H
13 #include <netinet/in.h>
14 #endif
15
16 #include "ntp.h"
17 #include "ntp_stdlib.h"
18
19
20 /* If the given string position points to a decimal digit, parse the
21 * number. If this is not possible, or the parsing did not consume the
22 * whole string, or if the result exceeds the maximum value, return the
23 * default value.
24 */
25 static unsigned long
_num_or_dflt(char * sval,unsigned long maxval,unsigned long defval)26 _num_or_dflt(
27 char * sval,
28 unsigned long maxval,
29 unsigned long defval
30 )
31 {
32 char * ep;
33 unsigned long num;
34
35 if (!(sval && isdigit(*(unsigned char*)sval)))
36 return defval;
37
38 num = strtoul(sval, &ep, 10);
39 if (!*ep && num <= maxval)
40 return num;
41
42 return defval;
43 }
44
45 /* If the given string position is not NULL and does not point to the
46 * terminator, replace the character with NUL and advance the pointer.
47 * Return the resulting position.
48 */
49 static inline char*
_chop(char * sp)50 _chop(
51 char * sp)
52 {
53 if (sp && *sp)
54 *sp++ = '\0';
55 return sp;
56 }
57
58 /* If the given string position points to the given char, advance the
59 * pointer and return the result. Otherwise, return NULL.
60 */
61 static inline char*
_skip(char * sp,int ch)62 _skip(
63 char * sp,
64 int ch)
65 {
66 if (sp && *(unsigned char*)sp == ch)
67 return (sp + 1);
68 return NULL;
69 }
70
71 /*
72 * decodenetnum convert text IP address and port to sockaddr_u
73 *
74 * Returns FALSE (->0) for failure, TRUE (->1) for success.
75 */
76 int
decodenetnum(const char * num,sockaddr_u * net)77 decodenetnum(
78 const char *num,
79 sockaddr_u *net
80 )
81 {
82 /* Building a parser is more fun in Haskell, but here we go...
83 *
84 * This works through 'inet_pton()' taking the brunt of the
85 * work, after some string manipulations to split off URI
86 * brackets, ports and scope identifiers. The heuristics are
87 * simple but must hold for all _VALID_ addresses. inet_pton()
88 * will croak on bad ones later, but replicating the whole
89 * parser logic to detect errors is wasteful.
90 */
91
92 sockaddr_u netnum;
93 char buf[64]; /* working copy of input */
94 char *haddr=buf;
95 unsigned int port=NTP_PORT, scope=0;
96 unsigned short afam=AF_UNSPEC;
97
98 /* copy input to working buffer with length check */
99 if (strlcpy(buf, num, sizeof(buf)) >= sizeof(buf))
100 return FALSE;
101
102 /* Identify address family and possibly the port, if given. If
103 * this results in AF_UNSPEC, we will fail in the next step.
104 */
105 if (*haddr == '[') {
106 char * endp = strchr(++haddr, ']');
107 if (endp) {
108 port = _num_or_dflt(_skip(_chop(endp), ':'),
109 0xFFFFu, port);
110 afam = strchr(haddr, ':') ? AF_INET6 : AF_INET;
111 }
112 } else {
113 char *col = strchr(haddr, ':');
114 char *dot = strchr(haddr, '.');
115 if (col == dot) {
116 /* no dot, no colon: bad! */
117 afam = AF_UNSPEC;
118 } else if (!col) {
119 /* no colon, only dot: IPv4! */
120 afam = AF_INET;
121 } else if (!dot || col < dot) {
122 /* no dot or 1st colon before 1st dot: IPv6! */
123 afam = AF_INET6;
124 } else {
125 /* 1st dot before 1st colon: must be IPv4 with port */
126 afam = AF_INET;
127 port = _num_or_dflt(_chop(col), 0xFFFFu, port);
128 }
129 }
130
131 /* Since we don't know about additional members in the address
132 * structures, we wipe the result buffer thoroughly:
133 */
134 memset(&netnum, 0, sizeof(netnum));
135
136 /* For AF_INET6, evaluate and remove any scope suffix. Have
137 * inet_pton() do the real work for AF_INET and AF_INET6, bail
138 * out otherwise:
139 */
140 switch (afam) {
141 case AF_INET:
142 if (inet_pton(afam, haddr, &netnum.sa4.sin_addr) <= 0)
143 return FALSE;
144 netnum.sa4.sin_port = htons((unsigned short)port);
145 break;
146
147 case AF_INET6:
148 scope = _num_or_dflt(_chop(strchr(haddr, '%')), 0xFFFFFFFFu, scope);
149 if (inet_pton(afam, haddr, &netnum.sa6.sin6_addr) <= 0)
150 return FALSE;
151 netnum.sa6.sin6_port = htons((unsigned short)port);
152 netnum.sa6.sin6_scope_id = scope;
153 break;
154
155 case AF_UNSPEC:
156 default:
157 return FALSE;
158 }
159
160 /* Collect the remaining pieces and feed the output, which was
161 * not touched so far:
162 */
163 netnum.sa.sa_family = afam;
164 memcpy(net, &netnum, sizeof(netnum));
165 return TRUE;
166 }
167