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dns server support from Nick Mathewson; tiny tweaks

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to the regression test from me to make it run on
systems where stack variables get initialized with
trash.


svn:r321
This commit is contained in:
Niels Provos 2007-02-08 16:39:15 +00:00
parent 3b8e27a58f
commit faf5f73a69
3 changed files with 925 additions and 13 deletions
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714
evdns.c
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@ -109,6 +109,10 @@
#include <netinet/in6.h> #include <netinet/in6.h>
#endif #endif
#ifdef WIN32
typedef int socklen_t;
#endif
#define EVDNS_LOG_DEBUG 0 #define EVDNS_LOG_DEBUG 0
#define EVDNS_LOG_WARN 1 #define EVDNS_LOG_WARN 1
@ -138,12 +142,12 @@ typedef unsigned int uint;
#define MAX_ADDRS 4 // maximum number of addresses from a single packet #define MAX_ADDRS 4 // maximum number of addresses from a single packet
// which we bother recording // which we bother recording
#define TYPE_A 1 #define TYPE_A EVDNS_TYPE_A
#define TYPE_CNAME 5 #define TYPE_CNAME 5
#define TYPE_PTR 12 #define TYPE_PTR EVDNS_TYPE_PTR
#define TYPE_AAAA 28 #define TYPE_AAAA EVDNS_TYPE_AAAA
#define CLASS_INET 1 #define CLASS_INET EVDNS_CLASS_INET
struct request { struct request {
u8 *request; // the dns packet data u8 *request; // the dns packet data
@ -214,6 +218,72 @@ struct nameserver {
static struct request *req_head = NULL, *req_waiting_head = NULL; static struct request *req_head = NULL, *req_waiting_head = NULL;
static struct nameserver *server_head = NULL; static struct nameserver *server_head = NULL;
// Represents a local port where we're listening for DNS requests. Right now,
// only UDP is supported.
struct evdns_server_port {
int socket; // socket we use to read queries and write replies.
int refcnt; // reference count.
char choked; // Are we currently blocked from writing?
char closing; // Are we trying to close this port, pending writes?
evdns_request_callback_fn_type user_callback; // Fn to handle requests
void *user_data; // Opaque pointer passed to user_callback
struct event event; // Read/write event
// circular list of replies that we want to write.
struct server_request *pending_replies;
};
// Represents part of a reply being built. (That is, a single RR.)
struct server_reply_item {
struct server_reply_item *next; // next item in sequence.
char *name; // name part of the RR
u16 type : 16; // The RR type
u16 class : 16; // The RR class (usually CLASS_INET)
u32 ttl; // The RR TTL
char is_name; // True iff data is a label
u16 datalen; // Length of data; -1 if data is a label
void *data; // The contents of the RR
};
// Represents a request that we've received as a DNS server, and holds
// the components of the reply as we're constructing it.
struct server_request {
// Pointers to the next and previous entries on the list of replies
// that we're waiting to write. Only set if we have tried to respond
// and gotten EAGAIN.
struct server_request *next_pending;
struct server_request *prev_pending;
u16 trans_id; // Transaction id.
struct evdns_server_port *port; // Which port received this request on?
struct sockaddr_storage addr; // Where to send the response
socklen_t addrlen; // length of addr
int n_answer; // how many answer RRs have been set?
int n_authority; // how many authority RRs have been set?
int n_additional; // how many additional RRs have been set?
struct server_reply_item *answer; // linked list of answer RRs
struct server_reply_item *authority; // linked list of authority RRs
struct server_reply_item *additional; // linked list of additional RRs
// Constructed response. Only set once we're ready to send a reply.
// Once this is set, the RR fields are cleared, and no more should be set.
char *response;
size_t response_len;
// Caller-visible fields: flags, questions.
struct evdns_server_request base;
};
// helper macro
#define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0))
// Given a pointer to an evdns_server_request, get the corresponding
// server_request.
#define TO_SERVER_REQUEST(base_ptr) \
((struct server_request*) \
(((char*)(base_ptr) - OFFSET_OF(struct server_request, base))))
// The number of good nameservers that we have // The number of good nameservers that we have
static int global_good_nameservers = 0; static int global_good_nameservers = 0;
@ -253,6 +323,13 @@ static u16 transaction_id_pick(void);
static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr); static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
static void request_submit(struct request *req); static void request_submit(struct request *req);
static int server_request_free(struct server_request *req);
static void server_request_free_answers(struct server_request *req);
static void server_port_free(struct evdns_server_port *port);
static void server_port_ready_callback(int fd, short events, void *arg);
static int strtoint(const char *const str);
#ifdef WIN32 #ifdef WIN32
static int static int
last_error(int sock) last_error(int sock)
@ -809,6 +886,7 @@ reply_parse(u8 *packet, int length) {
if (name_parse(packet, length, &j, reply.data.ptr.name, if (name_parse(packet, length, &j, reply.data.ptr.name,
sizeof(reply.data.ptr.name))<0) sizeof(reply.data.ptr.name))<0)
return -1; return -1;
ttl_r = MIN(ttl_r, ttl);
reply.have_answer = 1; reply.have_answer = 1;
break; break;
} else if (type == TYPE_AAAA && class == CLASS_INET) { } else if (type == TYPE_AAAA && class == CLASS_INET) {
@ -840,6 +918,84 @@ reply_parse(u8 *packet, int length) {
return 0; return 0;
err: err:
return -1; return -1;
}
// Parse a raw request (packet,length) sent to a nameserver port (port) from
// a DNS client (addr,addrlen), and if it's well-formed, call the corresponding
// callback.
static int
request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, socklen_t addrlen)
{
int j = 0; // index into packet
u16 _t; // used by the macros
char tmp_name[256]; // used by the macros
int i;
u16 trans_id, flags, questions, answers, authority, additional;
struct server_request *server_req = NULL;
// Get the header fields
GET16(trans_id);
GET16(flags);
GET16(questions);
GET16(answers);
GET16(authority);
GET16(additional);
if (flags & 0x8000) return -1; // Must not be an answer.
if (flags & 0x7800) return -1; // only standard queries are supported
flags &= 0x0300; // Only TC and RD get preserved.
server_req = malloc(sizeof(struct server_request));
if (server_req == NULL) return -1;
memset(server_req, 0, sizeof(struct server_request));
server_req->trans_id = trans_id;
memcpy(&server_req->addr, addr, addrlen);
server_req->addrlen = addrlen;
server_req->base.flags = flags;
server_req->base.nquestions = 0;
server_req->base.questions = malloc(sizeof(struct evdns_server_question *) * questions);
if (server_req->base.questions == NULL)
goto err;
for (i = 0; i < questions; ++i) {
u16 type, class;
struct evdns_server_question *q;
int namelen;
if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
goto err;
GET16(type);
GET16(class);
namelen = strlen(tmp_name);
q = malloc(sizeof(struct evdns_server_question) + namelen);
if (!q)
goto err;
q->type = type;
q->class = class;
memcpy(q->name, tmp_name, namelen+1);
server_req->base.questions[server_req->base.nquestions++] = q;
}
// Ignore answers, authority, and additional.
server_req->port = port;
port->refcnt++;
port->user_callback(&(server_req->base), port->user_data);
return 0;
err:
if (server_req) {
if (server_req->base.questions) {
for (i = 0; i < server_req->base.nquestions; ++i)
free(server_req->base.questions[i]);
free(server_req->base.questions);
}
free(server_req);
}
return -1;
#undef SKIP_NAME #undef SKIP_NAME
#undef GET32 #undef GET32
#undef GET16 #undef GET16
@ -951,6 +1107,60 @@ nameserver_read(struct nameserver *ns) {
} }
} }
// Read a packet from a DNS client on a server port s, parse it, and
// act accordingly.
static void
server_port_read(struct evdns_server_port *s) {
u8 packet[1500];
struct sockaddr_storage addr;
socklen_t addrlen;
int r;
for (;;) {
addrlen = sizeof(struct sockaddr_storage);
r = recvfrom(s->socket, packet, sizeof(packet), 0,
(struct sockaddr*) &addr, &addrlen);
if (r < 0) {
int err = last_error(s->socket);
if (error_is_eagain(err)) return;
log(EVDNS_LOG_WARN, "Error %s (%d) while reading request.",
strerror(err), err);
return;
}
request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
}
}
// Try to write all pending replies on a given DNS server port.
static void
server_port_flush(struct evdns_server_port *port)
{
while (port->pending_replies) {
struct server_request *req = port->pending_replies;
int r = sendto(port->socket, req->response, req->response_len, 0,
(struct sockaddr*) &req->addr, req->addrlen);
if (r < 0) {
int err = last_error(port->socket);
if (error_is_eagain(err))
return;
log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", strerror(err), err);
}
if (server_request_free(req)) {
// we released the last reference to req->port.
return;
}
}
// We have no more pending requests; stop listening for 'writeable' events.
(void) event_del(&port->event);
event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
server_port_ready_callback, port);
if (event_add(&port->event, NULL) < 0) {
log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
// ???? Do more?
}
}
// set if we are waiting for the ability to write to this server. // set if we are waiting for the ability to write to this server.
// if waiting is true then we ask libevent for EV_WRITE events, otherwise // if waiting is true then we ask libevent for EV_WRITE events, otherwise
// we stop these events. // we stop these events.
@ -987,6 +1197,22 @@ nameserver_ready_callback(int fd, short events, void *arg) {
} }
} }
// a callback function. Called by libevent when the kernel says that
// a server socket is ready for writing or reading.
static void
server_port_ready_callback(int fd, short events, void *arg) {
struct evdns_server_port *port = (struct evdns_server_port *) arg;
(void) fd;
if (events & EV_WRITE) {
port->choked = 0;
server_port_flush(port);
}
if (events & EV_READ) {
server_port_read(port);
}
}
/* This is an inefficient representation; only use it via the dnslabel_table_* /* This is an inefficient representation; only use it via the dnslabel_table_*
* functions, so that is can be safely replaced with something smarter later. */ * functions, so that is can be safely replaced with something smarter later. */
#define MAX_LABELS 128 #define MAX_LABELS 128
@ -1164,6 +1390,395 @@ evdns_request_data_build(const char *const name, const int name_len,
return (-1); return (-1);
} }
// exported function
struct evdns_server_port *
evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb, void *user_data)
{
struct evdns_server_port *port;
if (!(port = malloc(sizeof(struct evdns_server_port))))
return NULL;
memset(port, 0, sizeof(struct evdns_server_port));
assert(!is_tcp); // TCP sockets not yet implemented
port->socket = socket;
port->refcnt = 1;
port->choked = 0;
port->closing = 0;
port->user_callback = cb;
port->user_data = user_data;
port->pending_replies = NULL;
event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
server_port_ready_callback, port);
event_add(&port->event, NULL); // check return.
return port;
}
// exported function
void
evdns_close_server_port(struct evdns_server_port *port)
{
if (--port->refcnt == 0)
server_port_free(port);
port->closing = 1;
}
// exported function
int
evdns_server_request_add_reply(struct evdns_server_request *_req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data)
{
struct server_request *req = TO_SERVER_REQUEST(_req);
struct server_reply_item **itemp, *item;
int *countp;
if (req->response) /* have we already answered? */
return (-1);
switch (section) {
case EVDNS_ANSWER_SECTION:
itemp = &req->answer;
countp = &req->n_answer;
break;
case EVDNS_AUTHORITY_SECTION:
itemp = &req->authority;
countp = &req->n_authority;
break;
case EVDNS_ADDITIONAL_SECTION:
itemp = &req->additional;
countp = &req->n_additional;
break;
default:
return (-1);
}
while (*itemp) {
itemp = &((*itemp)->next);
}
item = malloc(sizeof(struct server_reply_item));
if (!item)
return -1;
item->next = NULL;
if (!(item->name = strdup(name))) {
free(item);
return -1;
}
item->type = type;
item->class = class;
item->ttl = ttl;
item->is_name = is_name != 0;
item->datalen = 0;
item->data = NULL;
if (data) {
if (item->is_name) {
if (!(item->data = strdup(data))) {
free(item->name);
free(item);
return -1;
}
item->datalen = -1;
} else {
if (!(item->data = malloc(datalen))) {
free(item->name);
free(item);
return -1;
}
item->datalen = datalen;
memcpy(item->data, data, datalen);
}
}
*itemp = item;
++(*countp);
return 0;
}
// exported function
int
evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
{
return evdns_server_request_add_reply(
req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
ttl, n*4, 0, addrs);
}
// exported function
int
evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
{
return evdns_server_request_add_reply(
req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
ttl, n*16, 0, addrs);
}
// exported function
int
evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
{
u32 a;
char buf[32];
assert(in || inaddr_name);
assert(!(in && inaddr_name));
if (in) {
a = ntohl(in->s_addr);
snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
(int)(u8)((a )&0xff),
(int)(u8)((a>>8 )&0xff),
(int)(u8)((a>>16)&0xff),
(int)(u8)((a>>24)&0xff));
inaddr_name = buf;
}
return evdns_server_request_add_reply(
req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
ttl, -1, 1, hostname);
}
// exported function
int
evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
{
return evdns_server_request_add_reply(
req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
ttl, -1, 1, cname);
}
static int
evdns_server_request_format_response(struct server_request *req, int err)
{
unsigned char buf[1500];
size_t buf_len = sizeof(buf);
off_t j = 0, r;
u16 _t;
u32 _t32;
int i;
u16 flags;
struct dnslabel_table table;
if (err < 0 || err > 15) return -1;
/* Set response bit and error code; copy OPCODE and RD fields from
* question; copy RA and AA if set by caller. */
flags = req->base.flags;
flags |= (0x8000 | err);
dnslabel_table_init(&table);
APPEND16(req->trans_id);
APPEND16(flags);
APPEND16(req->base.nquestions);
APPEND16(req->n_answer);
APPEND16(req->n_authority);
APPEND16(req->n_additional);
/* Add questions. */
for (i=0; i < req->base.nquestions; ++i) {
const char *s = req->base.questions[i]->name;
j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
if (j < 0) {
dnslabel_clear(&table);
return (int) j;
}
APPEND16(req->base.questions[i]->type);
APPEND16(req->base.questions[i]->class);
}
/* Add answer, authority, and additional sections. */
for (i=0; i<3; ++i) {
struct server_reply_item *item;
if (i==0)
item = req->answer;
else if (i==1)
item = req->authority;
else
item = req->additional;
while (item) {
r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
if (r < 0)
goto overflow;
j = r;
APPEND16(item->type);
APPEND16(item->class);
APPEND32(item->ttl);
if (item->is_name) {
off_t len_idx = j, name_start;
j += 2;
name_start = j;
r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
if (r < 0)
goto overflow;
j = r;
_t = htons( (j-name_start) );
memcpy(buf+len_idx, &_t, 2);
} else {
APPEND16(item->datalen);
if (j+item->datalen > (off_t)buf_len)
goto overflow;
memcpy(buf+j, item->data, item->datalen);
j += item->datalen;
}
item = item->next;
}
}
if (j > 512) {
overflow:
j = 512;
buf[3] |= 0x02; /* set the truncated bit. */
}
req->response_len = j;
if (!(req->response = malloc(req->response_len))) {
server_request_free_answers(req);
dnslabel_clear(&table);
return (-1);
}
memcpy(req->response, buf, req->response_len);
server_request_free_answers(req);
dnslabel_clear(&table);
return (0);
}
// exported function
int
evdns_server_request_respond(struct evdns_server_request *_req, int err)
{
struct server_request *req = TO_SERVER_REQUEST(_req);
struct evdns_server_port *port = req->port;
int r;
if (!req->response) {
if ((r = evdns_server_request_format_response(req, err))<0)
return r;
}
r = sendto(port->socket, req->response, req->response_len, 0,
(struct sockaddr*) &req->addr, req->addrlen);
if (r<0) {
int err = last_error(port->socket);
if (! error_is_eagain(err))
return -1;
if (port->pending_replies) {
req->prev_pending = port->pending_replies->prev_pending;
req->next_pending = port->pending_replies;
req->prev_pending->next_pending =
req->next_pending->prev_pending = req;
} else {
req->prev_pending = req->next_pending = req;
port->pending_replies = req;
port->choked = 1;
(void) event_del(&port->event);
event_set(&port->event, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
if (event_add(&port->event, NULL) < 0) {
log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
}
}
return 1;
}
if (server_request_free(req))
return 0;
if (req->port->pending_replies)
server_port_flush(port);
return 0;
}
// Free all storage held by RRs in req.
static void
server_request_free_answers(struct server_request *req)
{
struct server_reply_item *victim, *next, **list;
int i;
for (i = 0; i < 3; ++i) {
if (i==0)
list = &req->answer;
else if (i==1)
list = &req->authority;
else
list = &req->additional;
victim = *list;
while (victim) {
next = victim->next;
free(victim->name);
if (victim->data)
free(victim->data);
/* XXXX free(victim?) -NM */
victim = next;
}
*list = NULL;
}
}
// Free all storage held by req, and remove links to it.
// return true iff we just wound up freeing the server_port.
static int
server_request_free(struct server_request *req)
{
int i, rc=1;
if (req->base.questions) {
for (i = 0; i < req->base.nquestions; ++i)
free(req->base.questions[i]);
}
if (req->port) {
if (req->port->pending_replies == req) {
if (req->next_pending)
req->port->pending_replies = req->next_pending;
else
req->port->pending_replies = NULL;
}
rc = --req->port->refcnt;
}
if (req->response) {
free(req->response);
}
server_request_free_answers(req);
if (req->next_pending && req->next_pending != req) {
req->next_pending->prev_pending = req->prev_pending;
req->prev_pending->next_pending = req->next_pending;
}
if (rc == 0) {
server_port_free(req->port);
free(req);
return (1);
}
free(req);
return (0);
}
// Free all storage held by an evdns_server_port. Only called when
static void
server_port_free(struct evdns_server_port *port)
{
assert(port);
assert(!port->refcnt);
assert(!port->pending_replies);
if (port->socket > 0) {
CLOSE_SOCKET(port->socket);
port->socket = -1;
}
(void) event_del(&port->event);
// XXXX actually free the port? -NM
}
// exported function
int
evdns_server_request_drop(struct evdns_server_request *_req)
{
struct server_request *req = TO_SERVER_REQUEST(_req);
server_request_free(req);
return 0;
}
#undef APPEND16 #undef APPEND16
#undef APPEND32 #undef APPEND32
@ -1391,9 +2006,8 @@ evdns_resume(void)
return 0; return 0;
} }
// exported function static int
int _evdns_nameserver_add_impl(unsigned long int address, int port) {
evdns_nameserver_add(unsigned long int address) {
// first check to see if we already have this nameserver // first check to see if we already have this nameserver
const struct nameserver *server = server_head, *const started_at = server_head; const struct nameserver *server = server_head, *const started_at = server_head;
@ -1423,7 +2037,7 @@ evdns_nameserver_add(unsigned long int address) {
fcntl(ns->socket, F_SETFL, O_NONBLOCK); fcntl(ns->socket, F_SETFL, O_NONBLOCK);
#endif #endif
sin.sin_addr.s_addr = address; sin.sin_addr.s_addr = address;
sin.sin_port = htons(53); sin.sin_port = htons(port);
sin.sin_family = AF_INET; sin.sin_family = AF_INET;
if (connect(ns->socket, (struct sockaddr *) &sin, sizeof(sin)) != 0) { if (connect(ns->socket, (struct sockaddr *) &sin, sizeof(sin)) != 0) {
err = 2; err = 2;
@ -1465,13 +2079,39 @@ out1:
return err; return err;
} }
// exported function
int
evdns_nameserver_add(unsigned long int address) {
return _evdns_nameserver_add_impl(address, 53);
}
// exported function // exported function
int int
evdns_nameserver_ip_add(const char *ip_as_string) { evdns_nameserver_ip_add(const char *ip_as_string) {
struct in_addr ina; struct in_addr ina;
if (!inet_aton(ip_as_string, &ina)) int port;
return 4; char buf[20];
return evdns_nameserver_add(ina.s_addr); const char *cp;
cp = strchr(ip_as_string, ':');
if (! cp) {
cp = ip_as_string;
port = 53;
} else {
port = strtoint(cp+1);
if (port < 0 || port > 65535) {
return 4;
}
if ((cp-ip_as_string) >= (int)sizeof(buf)) {
return 4;
}
memcpy(buf, ip_as_string, cp-ip_as_string);
buf[cp-ip_as_string] = '\0';
cp = buf;
}
if (!inet_aton(cp, &ina)) {
return 4;
}
return _evdns_nameserver_add_impl(ina.s_addr, port);
} }
// insert into the tail of the queue // insert into the tail of the queue
@ -2078,7 +2718,7 @@ evdns_nameserver_ip_add_line(const char *ips) {
while (ISSPACE(*ips) || *ips == ',' || *ips == '\t') while (ISSPACE(*ips) || *ips == ',' || *ips == '\t')
++ips; ++ips;
addr = ips; addr = ips;
while (ISDIGIT(*ips) || *ips == '.') while (ISDIGIT(*ips) || *ips == '.' || *ips == ':')
++ips; ++ips;
buf = malloc(ips-addr+1); buf = malloc(ips-addr+1);
if (!buf) return 4; if (!buf) return 4;
@ -2350,6 +2990,37 @@ main_callback(int result, char type, int count, int ttl,
} }
fflush(stdout); fflush(stdout);
} }
void
evdns_server_callback(struct evdns_server_request *req, void *data)
{
int i, r;
(void)data;
/* dummy; give 192.168.11.11 as an answer for all A questions,
* give foo.bar.example.com as an answer for all PTR questions. */
for (i = 0; i < req->nquestions; ++i) {
u32 ans = htonl(0xc0a80b0bUL);
if (req->questions[i]->type == EVDNS_TYPE_A &&
req->questions[i]->class == EVDNS_CLASS_INET) {
printf(" -- replying for %s (A)\n", req->questions[i]->name);
r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
1, &ans, 10);
if (r<0)
printf("eeep, didn't work.\n");
} else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
req->questions[i]->class == EVDNS_CLASS_INET) {
printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
"foo.bar.example.com", 10);
} else {
printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
req->questions[i]->type, req->questions[i]->class);
}
}
r = evdns_request_respond(req, 0);
if (r<0)
printf("eeek, couldn't send reply.\n");
}
void void
logfn(int is_warn, const char *msg) { logfn(int is_warn, const char *msg) {
@ -2359,9 +3030,10 @@ logfn(int is_warn, const char *msg) {
int int
main(int c, char **v) { main(int c, char **v) {
int idx; int idx;
int reverse = 0, verbose = 1; int reverse = 0, verbose = 1, servertest = 0;
if (c<2) { if (c<2) {
fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]); fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]);
fprintf(stderr, "syntax: %s [-servertest]\n", v[0]);
return 1; return 1;
} }
idx = 1; idx = 1;
@ -2370,6 +3042,8 @@ main(int c, char **v) {
reverse = 1; reverse = 1;
else if (!strcmp(v[idx], "-v")) else if (!strcmp(v[idx], "-v"))
verbose = 1; verbose = 1;
else if (!strcmp(v[idx], "-servertest"))
servertest = 1;
else else
fprintf(stderr, "Unknown option %s\n", v[idx]); fprintf(stderr, "Unknown option %s\n", v[idx]);
++idx; ++idx;
@ -2378,6 +3052,20 @@ main(int c, char **v) {
if (verbose) if (verbose)
evdns_set_log_fn(logfn); evdns_set_log_fn(logfn);
evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf"); evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf");
if (servertest) {
int sock;
struct sockaddr_in my_addr;
sock = socket(PF_INET, SOCK_DGRAM, 0);
fcntl(sock, F_SETFL, O_NONBLOCK);
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(10053);
my_addr.sin_addr.s_addr = INADDR_ANY;
if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
perror("bind");
exit(1);
}
evdns_add_server_port(sock, 0, evdns_server_callback, NULL);
}
for (; idx < c; ++idx) { for (; idx < c; ++idx) {
if (reverse) { if (reverse) {
struct in_addr addr; struct in_addr addr;

45
evdns.h
View File

@ -317,4 +317,49 @@ void evdns_set_log_fn(evdns_debug_log_fn_type fn);
} }
#endif #endif
/*
* Structures and functions used to implement a DNS server.
*/
struct evdns_server_request {
int flags;
int nquestions;
struct evdns_server_question **questions;
};
struct evdns_server_question {
int type;
int class;
char name[1];
};
typedef void (*evdns_request_callback_fn_type)(struct evdns_server_request *, void *);
#define EVDNS_ANSWER_SECTION 0
#define EVDNS_AUTHORITY_SECTION 1
#define EVDNS_ADDITIONAL_SECTION 2
#define EVDNS_TYPE_A 1
#define EVDNS_TYPE_NS 2
#define EVDNS_TYPE_CNAME 5
#define EVDNS_TYPE_SOA 6
#define EVDNS_TYPE_PTR 12
#define EVDNS_TYPE_MX 15
#define EVDNS_TYPE_TXT 16
#define EVDNS_TYPE_AAAA 28
#define EVDNS_QTYPE_AXFR 252
#define EVDNS_QTYPE_ALL 255
#define EVDNS_CLASS_INET 1
struct evdns_server_port *evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type callback, void *user_data);
void evdns_close_server_port(struct evdns_server_port *port);
int evdns_server_request_add_reply(struct evdns_server_request *req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data);
int evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl);
int evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl);
int evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl);
int evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl);
int evdns_server_request_respond(struct evdns_server_request *req, int err);
int evdns_server_request_drop(struct evdns_server_request *req);
#endif // !EVENTDNS_H #endif // !EVENTDNS_H

179
test/regress_dns.c
View File

@ -170,9 +170,188 @@ dns_gethostbyaddr()
} }
} }
static int n_server_responses = 0;
static void
dns_server_request_cb(struct evdns_server_request *req, void *data)
{
int i, r;
const char TEST_ARPA[] = "11.11.168.192.in-addr.arpa";
for (i = 0; i < req->nquestions; ++i) {
struct in_addr ans;
ans.s_addr = htonl(0xc0a80b0bUL); // 192.168.11.11
if (req->questions[i]->type == EVDNS_TYPE_A &&
req->questions[i]->class == EVDNS_CLASS_INET &&
!strcmp(req->questions[i]->name, "zz.example.com")) {
r = evdns_server_request_add_a_reply(req, "zz.example.com",
1, &ans.s_addr, 12345);
if (r<0)
dns_ok = 0;
} else if (req->questions[i]->type == EVDNS_TYPE_AAAA &&
req->questions[i]->class == EVDNS_CLASS_INET &&
!strcmp(req->questions[i]->name, "zz.example.com")) {
char addr6[17] = "abcdefghijklmnop";
r = evdns_server_request_add_aaaa_reply(req, "zz.example.com",
1, addr6, 123);
if (r<0)
dns_ok = 0;
} else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
req->questions[i]->class == EVDNS_CLASS_INET &&
!strcmp(req->questions[i]->name, TEST_ARPA)) {
r = evdns_server_request_add_ptr_reply(req, NULL, TEST_ARPA,
"ZZ.EXAMPLE.COM", 54321);
if (r<0)
dns_ok = 0;
} else {
fprintf(stdout, "Unexpected question %d %d \"%s\" ",
req->questions[i]->type,
req->questions[i]->class,
req->questions[i]->name);
dns_ok = 0;
}
}
r = evdns_server_request_respond(req, 0);
if (r<0) {
fprintf(stdout, "Couldn't send reply. ");
dns_ok = 0;
}
}
void
dns_server_gethostbyname_cb(int result, char type, int count, int ttl,
void *addresses, void *arg)
{
if (result != DNS_ERR_NONE) {
fprintf(stdout, "Unexpected result %d. ", result);
dns_ok = 0;
goto out;
}
if (count != 1) {
fprintf(stdout, "Unexpected answer count %d. ", count);
dns_ok = 0;
goto out;
}
switch (type) {
case DNS_IPv4_A: {
struct in_addr *in_addrs = addresses;
if (in_addrs[0].s_addr != htonl(0xc0a80b0bUL) || ttl != 12345) {
fprintf(stdout, "Bad IPv4 response \"%s\" %d. ",
inet_ntoa(in_addrs[0]), ttl);
dns_ok = 0;
goto out;
}
break;
}
case DNS_IPv6_AAAA: {
#if defined (HAVE_STRUCT_IN6_ADDR) && defined(HAVE_INET_NTOP)
struct in6_addr *in6_addrs = addresses;
char buf[INET6_ADDRSTRLEN+1];
if (memcmp(&in6_addrs[0].s6_addr, "abcdefghijklmnop", 16)
|| ttl != 123) {
const char *b = inet_ntop(AF_INET6, &in6_addrs[0],buf,sizeof(buf));
fprintf(stdout, "Bad IPv6 response \"%s\" %d. ", b, ttl);
dns_ok = 0;
goto out;
}
#endif
break;
}
case DNS_PTR: {
char **addrs = addresses;
if (strcmp(addrs[0], "ZZ.EXAMPLE.COM") || ttl != 54321) {
fprintf(stdout, "Bad PTR response \"%s\" %d. ",
addrs[0], ttl);
dns_ok = 0;
goto out;
}
break;
}
default:
fprintf(stdout, "Bad response type %d. ", type);
dns_ok = 0;
}
out:
if (++n_server_responses == 3) {
event_loopexit(NULL);
}
}
void
dns_server()
{
int sock;
struct sockaddr_in my_addr;
struct evdns_server_port *port;
struct in_addr resolve_addr;
dns_ok = 1;
fprintf(stdout, "DNS server support: ");
/* Add ourself as the only nameserver, and make sure we really are
* the only nameserver. */
evdns_nameserver_ip_add("127.0.0.1:35353");
if (evdns_count_nameservers() != 1) {
fprintf(stdout, "Couldn't set up.\n");
exit(1);
}
/* Now configure a nameserver port. */
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock == -1) {
perror("socket");
exit(1);
}
#ifdef WIN32
{
u_long nonblocking = 1;
ioctlsocket(sock, FIONBIO, &nonblocking);
}
#else
fcntl(sock, F_SETFL, O_NONBLOCK);
#endif
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(35353);
my_addr.sin_addr.s_addr = htonl(0x7f000001UL);
if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr)) < 0) {
perror("bind");
exit (1);
}
port = evdns_add_server_port(sock, 0, dns_server_request_cb, NULL);
/* Send two queries. */
evdns_resolve_ipv4("zz.example.com", DNS_QUERY_NO_SEARCH,
dns_server_gethostbyname_cb, NULL);
evdns_resolve_ipv6("zz.example.com", DNS_QUERY_NO_SEARCH,
dns_server_gethostbyname_cb, NULL);
resolve_addr.s_addr = htonl(0xc0a80b0bUL); // 192.168.11.11
evdns_resolve_reverse(&resolve_addr, 0,
dns_server_gethostbyname_cb, NULL);
event_dispatch();
if (dns_ok) {
fprintf(stdout, "OK\n");
} else {
fprintf(stdout, "FAILED\n");
exit(1);
}
evdns_close_server_port(port);
evdns_shutdown(0); /* remove ourself as nameserver. */
#ifdef WIN32
CloseHandle(sock);
#else
close(sock);
#endif
}
void void
dns_suite(void) dns_suite(void)
{ {
dns_server(); /* Do this before we call evdns_init. */
evdns_init(); evdns_init();
dns_gethostbyname(); dns_gethostbyname();
dns_gethostbyname6(); dns_gethostbyname6();