]>
Commit | Line | Data |
---|---|---|
6644c1c7 MT |
1 | From 32fc6dbe03569d70dd394420ceb73532cf303c33 Mon Sep 17 00:00:00 2001 |
2 | From: Glen Huang <curvedmark@gmail.com> | |
3 | Date: Sat, 27 Dec 2014 15:28:12 +0000 | |
4 | Subject: [PATCH 21/55] Add --ignore-address option. | |
5 | ||
6 | --- | |
7 | CHANGELOG | 8 ++++++++ | |
8 | man/dnsmasq.8 | 6 ++++++ | |
9 | src/dnsmasq.h | 3 ++- | |
10 | src/forward.c | 4 ++++ | |
11 | src/option.c | 18 +++++++++++++++--- | |
12 | src/rfc1035.c | 37 +++++++++++++++++++++++++++++++++++++ | |
13 | 6 files changed, 72 insertions(+), 4 deletions(-) | |
14 | ||
15 | diff --git a/CHANGELOG b/CHANGELOG | |
16 | index 956b71a151db..2b6356bcfb02 100644 | |
17 | --- a/CHANGELOG | |
18 | +++ b/CHANGELOG | |
19 | @@ -22,6 +22,14 @@ version 2.73 | |
20 | ||
21 | Fix crash in DNSSEC code with long RRs. Thanks to Marco Davids | |
22 | for the bug report. | |
23 | + | |
24 | + Add --ignore-address option. Ignore replies to A-record | |
25 | + queries which include the specified address. No error is | |
26 | + generated, dnsmasq simply continues to listen for another | |
27 | + reply. This is useful to defeat blocking strategies which | |
28 | + rely on quickly supplying a forged answer to a DNS | |
29 | + request for certain domains, before the correct answer can | |
30 | + arrive. Thanks to Glen Huang for the patch. | |
31 | ||
32 | ||
33 | version 2.72 | |
34 | diff --git a/man/dnsmasq.8 b/man/dnsmasq.8 | |
35 | index 0b8e04f0a897..4236ba307df3 100644 | |
36 | --- a/man/dnsmasq.8 | |
37 | +++ b/man/dnsmasq.8 | |
38 | @@ -293,6 +293,12 @@ an advertising web page in response to queries for unregistered names, | |
39 | instead of the correct NXDOMAIN response. This option tells dnsmasq to | |
40 | fake the correct response when it sees this behaviour. As at Sept 2003 | |
41 | the IP address being returned by Verisign is 64.94.110.11 | |
42 | +.TP | |
43 | +.B \-B, --ignore-address=<ipaddr> | |
44 | +Ignore replies to A-record queries which include the specified address. | |
45 | +No error is generated, dnsmasq simply continues to listen for another reply. | |
46 | +This is useful to defeat blocking strategies which rely on quickly supplying a | |
47 | +forged answer to a DNS request for certain domain, before the correct answer can arrive. | |
48 | .TP | |
49 | .B \-f, --filterwin2k | |
50 | Later versions of windows make periodic DNS requests which don't get sensible answers from | |
51 | diff --git a/src/dnsmasq.h b/src/dnsmasq.h | |
52 | index 1dd61c5edba3..7bc982ddf73c 100644 | |
53 | --- a/src/dnsmasq.h | |
54 | +++ b/src/dnsmasq.h | |
55 | @@ -930,7 +930,7 @@ extern struct daemon { | |
56 | char *runfile; | |
57 | char *lease_change_command; | |
58 | struct iname *if_names, *if_addrs, *if_except, *dhcp_except, *auth_peers, *tftp_interfaces; | |
59 | - struct bogus_addr *bogus_addr; | |
60 | + struct bogus_addr *bogus_addr, *ignore_addr; | |
61 | struct server *servers; | |
62 | struct ipsets *ipsets; | |
63 | int log_fac; /* log facility */ | |
64 | @@ -1093,6 +1093,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen, | |
65 | time_t now, int *ad_reqd, int *do_bit); | |
66 | int check_for_bogus_wildcard(struct dns_header *header, size_t qlen, char *name, | |
67 | struct bogus_addr *addr, time_t now); | |
68 | +int check_for_ignored_address(struct dns_header *header, size_t qlen, struct bogus_addr *baddr); | |
69 | unsigned char *find_pseudoheader(struct dns_header *header, size_t plen, | |
70 | size_t *len, unsigned char **p, int *is_sign); | |
71 | int check_for_local_domain(char *name, time_t now); | |
72 | diff --git a/src/forward.c b/src/forward.c | |
73 | index 408a179a20f4..f28c7d51f708 100644 | |
74 | --- a/src/forward.c | |
75 | +++ b/src/forward.c | |
76 | @@ -724,6 +724,10 @@ void reply_query(int fd, int family, time_t now) | |
77 | if (!(forward = lookup_frec(ntohs(header->id), hash))) | |
78 | return; | |
79 | ||
80 | + if (daemon->ignore_addr && RCODE(header) == NOERROR && | |
81 | + check_for_ignored_address(header, n, daemon->ignore_addr)) | |
82 | + return; | |
83 | + | |
84 | if ((RCODE(header) == SERVFAIL || RCODE(header) == REFUSED) && | |
85 | !option_bool(OPT_ORDER) && | |
86 | forward->forwardall == 0) | |
87 | diff --git a/src/option.c b/src/option.c | |
88 | index 209fa6976609..907d0cf88de9 100644 | |
89 | --- a/src/option.c | |
90 | +++ b/src/option.c | |
91 | @@ -147,6 +147,7 @@ struct myoption { | |
92 | #define LOPT_LOCAL_SERVICE 335 | |
93 | #define LOPT_DNSSEC_TIME 336 | |
94 | #define LOPT_LOOP_DETECT 337 | |
95 | +#define LOPT_IGNORE_ADDR 338 | |
96 | ||
97 | #ifdef HAVE_GETOPT_LONG | |
98 | static const struct option opts[] = | |
99 | @@ -181,6 +182,7 @@ static const struct myoption opts[] = | |
100 | { "local-service", 0, 0, LOPT_LOCAL_SERVICE }, | |
101 | { "bogus-priv", 0, 0, 'b' }, | |
102 | { "bogus-nxdomain", 1, 0, 'B' }, | |
103 | + { "ignore-address", 1, 0, LOPT_IGNORE_ADDR }, | |
104 | { "selfmx", 0, 0, 'e' }, | |
105 | { "filterwin2k", 0, 0, 'f' }, | |
106 | { "pid-file", 2, 0, 'x' }, | |
107 | @@ -457,6 +459,7 @@ static struct { | |
108 | { LOPT_QUIET_RA, OPT_QUIET_RA, NULL, gettext_noop("Do not log RA."), NULL }, | |
109 | { LOPT_LOCAL_SERVICE, OPT_LOCAL_SERVICE, NULL, gettext_noop("Accept queries only from directly-connected networks"), NULL }, | |
110 | { LOPT_LOOP_DETECT, OPT_LOOP_DETECT, NULL, gettext_noop("Detect and remove DNS forwarding loops"), NULL }, | |
111 | + { LOPT_IGNORE_ADDR, ARG_DUP, "<ipaddr>", gettext_noop("Ignore DNS responses containing ipaddr."), NULL }, | |
112 | { 0, 0, NULL, NULL, NULL } | |
113 | }; | |
114 | ||
115 | @@ -2119,14 +2122,23 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma | |
116 | break; | |
117 | ||
118 | case 'B': /* --bogus-nxdomain */ | |
119 | - { | |
120 | + case LOPT_IGNORE_ADDR: /* --ignore-address */ | |
121 | + { | |
122 | struct in_addr addr; | |
123 | unhide_metas(arg); | |
124 | if (arg && (inet_pton(AF_INET, arg, &addr) > 0)) | |
125 | { | |
126 | struct bogus_addr *baddr = opt_malloc(sizeof(struct bogus_addr)); | |
127 | - baddr->next = daemon->bogus_addr; | |
128 | - daemon->bogus_addr = baddr; | |
129 | + if (option == 'B') | |
130 | + { | |
131 | + baddr->next = daemon->bogus_addr; | |
132 | + daemon->bogus_addr = baddr; | |
133 | + } | |
134 | + else | |
135 | + { | |
136 | + baddr->next = daemon->ignore_addr; | |
137 | + daemon->ignore_addr = baddr; | |
138 | + } | |
139 | baddr->addr = addr; | |
140 | } | |
141 | else | |
142 | diff --git a/src/rfc1035.c b/src/rfc1035.c | |
143 | index bdeb3fb10e68..75c4266b47dd 100644 | |
144 | --- a/src/rfc1035.c | |
145 | +++ b/src/rfc1035.c | |
146 | @@ -1328,6 +1328,43 @@ int check_for_bogus_wildcard(struct dns_header *header, size_t qlen, char *name, | |
147 | return 0; | |
148 | } | |
149 | ||
150 | +int check_for_ignored_address(struct dns_header *header, size_t qlen, struct bogus_addr *baddr) | |
151 | +{ | |
152 | + unsigned char *p; | |
153 | + int i, qtype, qclass, rdlen; | |
154 | + struct bogus_addr *baddrp; | |
155 | + | |
156 | + /* skip over questions */ | |
157 | + if (!(p = skip_questions(header, qlen))) | |
158 | + return 0; /* bad packet */ | |
159 | + | |
160 | + for (i = ntohs(header->ancount); i != 0; i--) | |
161 | + { | |
162 | + if (!(p = skip_name(p, header, qlen, 10))) | |
163 | + return 0; /* bad packet */ | |
164 | + | |
165 | + GETSHORT(qtype, p); | |
166 | + GETSHORT(qclass, p); | |
167 | + p += 4; /* TTL */ | |
168 | + GETSHORT(rdlen, p); | |
169 | + | |
170 | + if (qclass == C_IN && qtype == T_A) | |
171 | + { | |
172 | + if (!CHECK_LEN(header, p, qlen, INADDRSZ)) | |
173 | + return 0; | |
174 | + | |
175 | + for (baddrp = baddr; baddrp; baddrp = baddrp->next) | |
176 | + if (memcmp(&baddrp->addr, p, INADDRSZ) == 0) | |
177 | + return 1; | |
178 | + } | |
179 | + | |
180 | + if (!ADD_RDLEN(header, p, qlen, rdlen)) | |
181 | + return 0; | |
182 | + } | |
183 | + | |
184 | + return 0; | |
185 | +} | |
186 | + | |
187 | int add_resource_record(struct dns_header *header, char *limit, int *truncp, int nameoffset, unsigned char **pp, | |
188 | unsigned long ttl, int *offset, unsigned short type, unsigned short class, char *format, ...) | |
189 | { | |
190 | -- | |
191 | 2.1.0 | |
192 |