1 /*
2 * libc/inet/ethers.c
3 *
4 * Programmatic interface for the /etc/ethers file
5 *
6 * Copyright 2007 by Matthew Wilcox <matthew@wil.cx>
7 *
8 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
9 */
10
11 #include <ctype.h>
12 #include <stdio.h>
13 #include <string.h>
14 #include <netinet/ether.h>
15
16 #define ETHER_LINE_LEN 256
17
18 /*
19 * Internal function which returns a pointer to the part of the line
20 * with the start of the hostname, or NULL if we couldn't parse the line.
21 * Note that this line may have a comment symbol on it somewhere; if so
22 * it will return NULL if the # is before or within the ether_addr, and
23 * succeed if the # is before or within the host. It's up to the callers
24 * to be aware of this.
25 *
26 * I would have preferred to write a NUL to the location of the comment
27 * character, but ether_line takes a const argument. See __ether_line_w.
28 */
__ether_line(const char * line,struct ether_addr * addr)29 static const char *__ether_line(const char *line, struct ether_addr *addr)
30 {
31 struct ether_addr *res = ether_aton_r(line, addr);
32 if (!res)
33 return NULL;
34
35 while (*line && (*line != ' ') && (*line != '\t'))
36 line++;
37 while (*line && ((*line == ' ') || (*line == '\t')))
38 line++;
39 return (*line) ? line : NULL;
40 }
41
42 /*
43 * Strips out the comment before calling __ether_line. We can do this,
44 * since we know the buffer is writable.
45 */
__ether_line_w(char * line,struct ether_addr * addr)46 static const char *__ether_line_w(char *line, struct ether_addr *addr)
47 {
48 char *end = strchr(line, '#');
49 if (!end)
50 end = strchr(line, '\n');
51 if (end)
52 *end = '\0';
53 return __ether_line(line, addr);
54 }
55
ether_line(const char * line,struct ether_addr * addr,char * hostname)56 int ether_line(const char *line, struct ether_addr *addr, char *hostname)
57 {
58 const char *name = __ether_line(line, addr);
59 if (!name)
60 return -1;
61
62 while (*name) {
63 if ((*name == '#') || isspace(*name))
64 break;
65 *hostname++ = *name++;
66 }
67 *hostname = '\0';
68
69 return 0;
70 }
71
ether_ntohost(char * hostname,const struct ether_addr * addr)72 int ether_ntohost(char *hostname, const struct ether_addr *addr)
73 {
74 int res = -1;
75 FILE *fp;
76 char buf[ETHER_LINE_LEN];
77
78 fp = fopen(ETHER_FILE_NAME, "r");
79 if (!fp)
80 return -1;
81
82 while (fgets(buf, sizeof(buf), fp)) {
83 struct ether_addr tmp_addr;
84 const char *cp = __ether_line_w(buf, &tmp_addr);
85 if (!cp)
86 continue;
87 if (memcmp(addr, &tmp_addr, sizeof(tmp_addr)))
88 continue;
89
90 strcpy(hostname, cp);
91 res = 0;
92 break;
93 }
94
95 fclose(fp);
96 return res;
97 }
98
ether_hostton(const char * hostname,struct ether_addr * addr)99 int ether_hostton(const char *hostname, struct ether_addr *addr)
100 {
101 int res = -1;
102 FILE *fp;
103 char buf[ETHER_LINE_LEN];
104
105 fp = fopen(ETHER_FILE_NAME, "r");
106 if (!fp)
107 return -1;
108
109 while (fgets(buf, sizeof(buf), fp)) {
110 const char *cp = __ether_line_w(buf, addr);
111 if (!cp)
112 continue;
113 if (strcasecmp(hostname, cp))
114 continue;
115
116 res = 0;
117 break;
118 }
119
120 fclose(fp);
121 return res;
122 }
123