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