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@@ -407,7 +407,7 @@ struct server_request {
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struct server_request *next_pending;
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struct server_request *prev_pending;
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- u16 trans_id;
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+ u16 trans_id;
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struct evdns_server_port *port;
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struct sockaddr_storage addr;
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socklen_t addrlen;
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@@ -423,7 +423,7 @@ struct server_request {
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char *response;
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size_t response_len;
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- struct evdns_server_request base;
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+ struct evdns_server_request base;
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};
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#define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0))
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@@ -970,14 +970,14 @@ reply_parse(u8 *packet, int length)
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reply.type = req->request_type;
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- // skip over each question in the reply
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+ // skip over each question in the reply
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for (i = 0; i < questions; ++i) {
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// the question looks like
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// <label:name><u16:type><u16:class>
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SKIP_NAME;
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j += 4;
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if (j >= length) return -1;
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- }
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+ }
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// now we have the answer section which looks like
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// <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
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@@ -995,7 +995,7 @@ reply_parse(u8 *packet, int length)
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// log("@%d, Name %s, type %d, class %d, j=%d", pre, tmp_name, (int)type, (int)class, j);
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- if (type == TYPE_A && class == CLASS_INET) {
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+ if (type == TYPE_A && class == CLASS_INET) {
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int addrcount, addrtocopy;
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if (req->request_type != TYPE_A) {
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j += datalength; continue;
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@@ -1064,6 +1064,8 @@ request_parse(u8 *packet, int length, struct evdns_server_port *port, struct soc
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GET16(additional);
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if (flags & 0x8000) return -1; // Must not be an answer.
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+ if (flags & 0x7800) return -1; // only standard queries are supported
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+ flags &= 0x0300; // Only TC and RD get preserved.
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server_req = malloc(sizeof(struct server_request));
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if (server_req == NULL) return -1;
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@@ -1384,7 +1386,7 @@ dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
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#define APPEND16(x) do { \
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if (j + 2 > (off_t)buf_len) \
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- return (-2); \
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+ goto overflow; \
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_t = htons(x); \
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memcpy(buf + j, &_t, 2); \
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j += 2; \
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@@ -1429,6 +1431,8 @@ dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
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// in which case the zero is already there
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if (!j || buf[j-1]) buf[j++] = 0;
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return j;
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+ overflow:
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+ return (-2);
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}
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// Finds the length of a dns request for a DNS name of the given
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@@ -1454,13 +1458,12 @@ evdns_request_data_build(const char *const name, const int name_len, const u16 t
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#define APPEND32(x) do { \
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if (j + 4 > (off_t)buf_len) \
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- return (-1); \
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+ goto overflow; \
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_t32 = htonl(x); \
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memcpy(buf + j, &_t32, 4); \
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j += 4; \
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} while (0)
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-
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APPEND16(trans_id);
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APPEND16(0x0100); // standard query, recusion needed
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APPEND16(1); // one question
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@@ -1477,6 +1480,8 @@ evdns_request_data_build(const char *const name, const int name_len, const u16 t
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APPEND16(class);
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return (int)j;
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+ overflow:
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+ return (-1);
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}
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// exported function
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@@ -1615,16 +1620,24 @@ evdns_request_add_cname_reply(struct evdns_server_request *req, const char *name
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}
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static int
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-evdns_request_response_format(struct server_request *req, int flags)
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+evdns_request_response_format(struct server_request *req, int err)
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{
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unsigned char buf[1500];
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size_t buf_len = sizeof(buf);
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- off_t j = 0;
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+ off_t j = 0, r;
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u16 _t;
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u32 _t32;
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int i;
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+ u16 flags;
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struct dnslabel_table table;
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+ if (err < 0 || err > 15) return -1;
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+
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+ /* Set response bit and error code; copy OPCODE and RD fields from
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+ * question; copy RA and AA if set by caller. */
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+ flags = req->base.flags;
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+ flags |= (0x8000 | err);
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+
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dnslabel_table_init(&table); // XXXX need to call dnslable_table_clear.
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APPEND16(req->trans_id);
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APPEND16(flags);
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@@ -1643,7 +1656,7 @@ evdns_request_response_format(struct server_request *req, int flags)
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APPEND16(req->base.questions[i]->class);
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}
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- /* Add answer-like sections. */
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+ /* Add answer, authority, and additional sections. */
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for (i=0; i<3; ++i) {
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struct server_request_item *item;
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if (i==0)
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@@ -1653,9 +1666,10 @@ evdns_request_response_format(struct server_request *req, int flags)
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else
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item = req->additional;
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while (item) {
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- j = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
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- if (j < 0)
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- return (int) j;
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+ r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
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+ if (r < 0)
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+ goto overflow;
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+ j = r;
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APPEND16(item->type);
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APPEND16(item->class);
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@@ -1664,15 +1678,16 @@ evdns_request_response_format(struct server_request *req, int flags)
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off_t len_idx = j, name_start;
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j += 2;
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name_start = j;
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- j = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
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- if (j < 0)
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- return (int) j;
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+ r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
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+ if (r < 0)
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+ goto overflow;
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+ j = r;
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_t = htons( (j-name_start) );
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memcpy(buf+len_idx, &_t, 2);
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} else {
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APPEND16(item->datalen);
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if (j+item->datalen > (off_t)buf_len)
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- return -1;
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+ goto overflow;
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memcpy(buf+j, item->data, item->datalen);
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j += item->datalen;
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}
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@@ -1680,11 +1695,20 @@ evdns_request_response_format(struct server_request *req, int flags)
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}
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}
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+ if (j > 512) {
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+overflow:
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+ j = 512;
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+ buf[3] |= 0x02; /* set the truncated bit. */
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+ }
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+
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req->response_len = j;
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- if (!(req->response = malloc(req->response_len)))
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+
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+ if (!(req->response = malloc(req->response_len))) {
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+ evdns_server_request_free_answers(req);
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+ dnslabel_clear(&table);
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return -1;
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+ }
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memcpy(req->response, buf, req->response_len);
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-
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evdns_server_request_free_answers(req);
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dnslabel_clear(&table);
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return 0;
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@@ -1692,13 +1716,13 @@ evdns_request_response_format(struct server_request *req, int flags)
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// exported function
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int
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-evdns_request_respond(struct evdns_server_request *_req, int flags)
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+evdns_request_respond(struct evdns_server_request *_req, int err)
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{
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struct server_request *req = TO_SERVER_REQUEST(_req);
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struct evdns_server_port *port = req->port;
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int r;
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if (!req->response) {
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- if ((r = evdns_request_response_format(req, flags))<0)
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+ if ((r = evdns_request_response_format(req, err))<0)
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return r;
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}
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@@ -1816,7 +1840,7 @@ evdns_request_timeout_callback(int fd, short events, void *arg) {
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req->ns->timedout++;
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if (req->ns->timedout > global_max_nameserver_timeout) {
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- req->ns->timedout = 0;
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+ req->ns->timedout = 0;
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nameserver_failed(req->ns, "request timed out.");
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}
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@@ -2149,12 +2173,12 @@ request_new(int type, const char *name, int flags, evdns_callback_type callback,
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// request data lives just after the header
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req->request = ((u8 *) req) + sizeof(struct request);
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- // denotes that the request data shouldn't be free()ed
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+ // denotes that the request data shouldn't be free()ed
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req->request_appended = 1;
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rlen = evdns_request_data_build(name, name_len, trans_id,
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- type, CLASS_INET, req->request, request_max_len);
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+ type, CLASS_INET, req->request, request_max_len);
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if (rlen < 0)
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- goto err1;
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+ goto err1;
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req->request_len = rlen;
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req->trans_id = trans_id;
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req->tx_count = 0;
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@@ -2933,7 +2957,7 @@ evdns_server_callback(struct evdns_server_request *req, void *data)
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}
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}
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- r = evdns_request_respond(req, 0x8000);
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+ r = evdns_request_respond(req, 0);
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if (r<0)
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printf("eeek, couldn't send reply.\n");
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}
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