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1 | /* | |
2 | * Charybdis: an advanced ircd | |
3 | * ip_cloaking.c: provide user hostname cloaking | |
4 | * | |
5 | * Written originally by nenolod, altered to use FNV by Elizabeth in 2008 | |
6 | */ | |
7 | ||
8 | #include "stdinc.h" | |
9 | #include "modules.h" | |
10 | #include "hook.h" | |
11 | #include "client.h" | |
12 | #include "ircd.h" | |
13 | #include "send.h" | |
14 | #include "hash.h" | |
15 | #include "s_conf.h" | |
16 | #include "s_user.h" | |
17 | #include "s_serv.h" | |
18 | #include "numeric.h" | |
19 | ||
20 | static const char ip_cloaking_desc[] = "IP cloaking module that uses user mode +h"; | |
21 | ||
22 | static int | |
23 | _modinit(void) | |
24 | { | |
25 | /* add the usermode to the available slot */ | |
26 | user_modes['h'] = find_umode_slot(); | |
27 | construct_umodebuf(); | |
28 | ||
29 | return 0; | |
30 | } | |
31 | ||
32 | static void | |
33 | _moddeinit(void) | |
34 | { | |
35 | /* disable the umode and remove it from the available list */ | |
36 | user_modes['h'] = 0; | |
37 | construct_umodebuf(); | |
38 | } | |
39 | ||
40 | static void check_umode_change(void *data); | |
41 | static void check_new_user(void *data); | |
42 | mapi_hfn_list_av1 ip_cloaking_hfnlist[] = { | |
43 | { "umode_changed", (hookfn) check_umode_change }, | |
44 | { "new_local_user", (hookfn) check_new_user }, | |
45 | { NULL, NULL } | |
46 | }; | |
47 | ||
48 | DECLARE_MODULE_AV2(ip_cloaking, _modinit, _moddeinit, NULL, NULL, | |
49 | ip_cloaking_hfnlist, NULL, NULL, ip_cloaking_desc); | |
50 | ||
51 | static void | |
52 | distribute_hostchange(struct Client *client_p, char *newhost) | |
53 | { | |
54 | if (newhost != client_p->orighost) | |
55 | sendto_one_numeric(client_p, RPL_HOSTHIDDEN, "%s :is now your hidden host", | |
56 | newhost); | |
57 | else | |
58 | sendto_one_numeric(client_p, RPL_HOSTHIDDEN, "%s :hostname reset", | |
59 | newhost); | |
60 | ||
61 | sendto_server(NULL, NULL, | |
62 | CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s :%s", | |
63 | use_id(&me), use_id(client_p), newhost); | |
64 | sendto_server(NULL, NULL, | |
65 | CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s", | |
66 | use_id(&me), use_id(client_p), newhost); | |
67 | ||
68 | change_nick_user_host(client_p, client_p->name, client_p->username, newhost, 0, "Changing host"); | |
69 | ||
70 | if (newhost != client_p->orighost) | |
71 | SetDynSpoof(client_p); | |
72 | else | |
73 | ClearDynSpoof(client_p); | |
74 | } | |
75 | ||
76 | static void | |
77 | do_host_cloak_ip(const char *inbuf, char *outbuf) | |
78 | { | |
79 | /* None of the characters in this table can be valid in an IP */ | |
80 | char chartable[] = "ghijklmnopqrstuvwxyz"; | |
81 | char *tptr; | |
82 | uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32); | |
83 | int sepcount = 0; | |
84 | int totalcount = 0; | |
85 | int ipv6 = 0; | |
86 | ||
87 | rb_strlcpy(outbuf, inbuf, HOSTLEN + 1); | |
88 | ||
89 | if (strchr(outbuf, ':')) | |
90 | { | |
91 | ipv6 = 1; | |
92 | ||
93 | /* Damn you IPv6... | |
94 | * We count the number of colons so we can calculate how much | |
95 | * of the host to cloak. This is because some hostmasks may not | |
96 | * have as many octets as we'd like. | |
97 | * | |
98 | * We have to do this ahead of time because doing this during | |
99 | * the actual cloaking would get ugly | |
100 | */ | |
101 | for (tptr = outbuf; *tptr != '\0'; tptr++) | |
102 | if (*tptr == ':') | |
103 | totalcount++; | |
104 | } | |
105 | else if (!strchr(outbuf, '.')) | |
106 | return; | |
107 | ||
108 | for (tptr = outbuf; *tptr != '\0'; tptr++) | |
109 | { | |
110 | if (*tptr == ':' || *tptr == '.') | |
111 | { | |
112 | sepcount++; | |
113 | continue; | |
114 | } | |
115 | ||
116 | if (ipv6 && sepcount < totalcount / 2) | |
117 | continue; | |
118 | ||
119 | if (!ipv6 && sepcount < 2) | |
120 | continue; | |
121 | ||
122 | *tptr = chartable[(*tptr + accum) % 20]; | |
123 | accum = (accum << 1) | (accum >> 31); | |
124 | } | |
125 | } | |
126 | ||
127 | static void | |
128 | do_host_cloak_host(const char *inbuf, char *outbuf) | |
129 | { | |
130 | char b26_alphabet[] = "abcdefghijklmnopqrstuvwxyz"; | |
131 | char *tptr; | |
132 | uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32); | |
133 | ||
134 | rb_strlcpy(outbuf, inbuf, HOSTLEN + 1); | |
135 | ||
136 | /* pass 1: scramble first section of hostname using base26 | |
137 | * alphabet toasted against the FNV hash of the string. | |
138 | * | |
139 | * numbers are not changed at this time, only letters. | |
140 | */ | |
141 | for (tptr = outbuf; *tptr != '\0'; tptr++) | |
142 | { | |
143 | if (*tptr == '.') | |
144 | break; | |
145 | ||
146 | if (isdigit((unsigned char)*tptr) || *tptr == '-') | |
147 | continue; | |
148 | ||
149 | *tptr = b26_alphabet[(*tptr + accum) % 26]; | |
150 | ||
151 | /* Rotate one bit to avoid all digits being turned odd or even */ | |
152 | accum = (accum << 1) | (accum >> 31); | |
153 | } | |
154 | ||
155 | /* pass 2: scramble each number in the address */ | |
156 | for (tptr = outbuf; *tptr != '\0'; tptr++) | |
157 | { | |
158 | if (isdigit((unsigned char)*tptr)) | |
159 | *tptr = '0' + (*tptr + accum) % 10; | |
160 | ||
161 | accum = (accum << 1) | (accum >> 31); | |
162 | } | |
163 | } | |
164 | ||
165 | static void | |
166 | check_umode_change(void *vdata) | |
167 | { | |
168 | hook_data_umode_changed *data = (hook_data_umode_changed *)vdata; | |
169 | struct Client *source_p = data->client; | |
170 | ||
171 | if (!MyClient(source_p)) | |
172 | return; | |
173 | ||
174 | /* didn't change +h umode, we don't need to do anything */ | |
175 | if (!((data->oldumodes ^ source_p->umodes) & user_modes['h'])) | |
176 | return; | |
177 | ||
178 | if (source_p->umodes & user_modes['h']) | |
179 | { | |
180 | if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost))) | |
181 | { | |
182 | source_p->umodes &= ~user_modes['h']; | |
183 | return; | |
184 | } | |
185 | if (strcmp(source_p->host, source_p->localClient->mangledhost)) | |
186 | { | |
187 | distribute_hostchange(source_p, source_p->localClient->mangledhost); | |
188 | } | |
189 | else /* not really nice, but we need to send this numeric here */ | |
190 | sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host", | |
191 | source_p->host); | |
192 | } | |
193 | else if (!(source_p->umodes & user_modes['h'])) | |
194 | { | |
195 | if (source_p->localClient->mangledhost != NULL && | |
196 | !strcmp(source_p->host, source_p->localClient->mangledhost)) | |
197 | { | |
198 | distribute_hostchange(source_p, source_p->orighost); | |
199 | } | |
200 | } | |
201 | } | |
202 | ||
203 | static void | |
204 | check_new_user(void *vdata) | |
205 | { | |
206 | struct Client *source_p = (void *)vdata; | |
207 | ||
208 | if (IsIPSpoof(source_p)) | |
209 | { | |
210 | source_p->umodes &= ~user_modes['h']; | |
211 | return; | |
212 | } | |
213 | source_p->localClient->mangledhost = rb_malloc(HOSTLEN + 1); | |
214 | if (!irccmp(source_p->orighost, source_p->sockhost)) | |
215 | do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost); | |
216 | else | |
217 | do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost); | |
218 | if (IsDynSpoof(source_p)) | |
219 | source_p->umodes &= ~user_modes['h']; | |
220 | if (source_p->umodes & user_modes['h']) | |
221 | { | |
222 | rb_strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host)); | |
223 | if (irccmp(source_p->host, source_p->orighost)) | |
224 | SetDynSpoof(source_p); | |
225 | } | |
226 | } |