lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 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 | */ |
| 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 | */ |
| 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 | |
| 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 | |
| 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 | |
| 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 | } |