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-rw-r--r--source4/libcli/resolve/dns_ex.c671
1 files changed, 671 insertions, 0 deletions
diff --git a/source4/libcli/resolve/dns_ex.c b/source4/libcli/resolve/dns_ex.c
new file mode 100644
index 0000000..b8447be
--- /dev/null
+++ b/source4/libcli/resolve/dns_ex.c
@@ -0,0 +1,671 @@
+/*
+ Unix SMB/CIFS implementation.
+
+ async getaddrinfo()/dns_lookup() name resolution module
+
+ Copyright (C) Andrew Tridgell 2005
+ Copyright (C) Stefan Metzmacher 2008
+ Copyright (C) Matthieu Patou 2011
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ this module uses a fork() per getaddrinfo() or dns_looup() call.
+ At first that might seem crazy, but it is actually very fast,
+ and solves many of the tricky problems of keeping a child
+ hanging around in a librar (like what happens when the parent forks).
+ We use a talloc destructor to ensure that the child is cleaned up
+ when we have finished with this name resolution.
+*/
+
+#include "includes.h"
+#include "system/network.h"
+#include "system/filesys.h"
+#include "lib/socket/socket.h"
+#include "libcli/composite/composite.h"
+#include "librpc/gen_ndr/ndr_nbt.h"
+#include "libcli/resolve/resolve.h"
+#include "lib/util/util_net.h"
+#include "lib/addns/dnsquery.h"
+#include "lib/addns/dns.h"
+#include "lib/util/sys_rw.h"
+#include "lib/util/smb_strtox.h"
+#include <arpa/nameser.h>
+#include <resolv.h>
+
+struct dns_ex_state {
+ bool do_fallback;
+ uint32_t flags;
+ uint16_t port;
+ struct nbt_name name;
+ struct socket_address **addrs;
+ char **names;
+ pid_t child;
+ int child_fd;
+ struct tevent_fd *fde;
+ struct tevent_context *event_ctx;
+};
+
+/*
+ kill off a wayward child if needed. This allows us to stop an async
+ name resolution without leaving a potentially blocking call running
+ in a child
+*/
+static int dns_ex_destructor(struct dns_ex_state *state)
+{
+ int status;
+
+ kill(state->child, SIGTERM);
+ if (waitpid(state->child, &status, WNOHANG) == 0) {
+ kill(state->child, SIGKILL);
+ waitpid(state->child, &status, 0);
+ }
+
+ return 0;
+}
+
+struct dns_records_container {
+ char **list;
+ uint32_t count;
+};
+
+static int reply_to_addrs(TALLOC_CTX *mem_ctx, uint32_t *a_num,
+ char ***cur_addrs, uint32_t total,
+ struct dns_request *reply, int port)
+{
+ char addrstr[INET6_ADDRSTRLEN];
+ struct dns_rrec *rr;
+ char **addrs;
+ uint32_t i;
+ const char *addr;
+
+ /* at most we over-allocate here, but not by much */
+ addrs = talloc_realloc(mem_ctx, *cur_addrs, char *,
+ total + reply->num_answers);
+ if (!addrs) {
+ return 0;
+ }
+ *cur_addrs = addrs;
+
+ for (i = 0; i < reply->num_answers; i++) {
+ rr = reply->answers[i];
+
+ /* we are only interested in the IN class */
+ if (rr->r_class != DNS_CLASS_IN) {
+ continue;
+ }
+
+ if (rr->type == QTYPE_NS) {
+ /*
+ * After the record for NS will come the A or AAAA
+ * record of the NS.
+ */
+ break;
+ }
+
+ /* verify we actually have a record here */
+ if (!rr->data) {
+ continue;
+ }
+
+ /* we are only interested in A and AAAA records */
+ switch (rr->type) {
+ case QTYPE_A:
+ addr = inet_ntop(AF_INET,
+ (struct in_addr *)rr->data,
+ addrstr, sizeof(addrstr));
+ if (addr == NULL) {
+ continue;
+ }
+ break;
+ case QTYPE_AAAA:
+#ifdef HAVE_IPV6
+ addr = inet_ntop(AF_INET6,
+ (struct in6_addr *)rr->data,
+ addrstr, sizeof(addrstr));
+#else
+ addr = NULL;
+#endif
+ if (addr == NULL) {
+ continue;
+ }
+ break;
+ default:
+ continue;
+ }
+
+ addrs[total] = talloc_asprintf(addrs, "%s@%u/%s",
+ addrstr, port,
+ rr->name->pLabelList->label);
+ if (addrs[total]) {
+ total++;
+ if (rr->type == QTYPE_A) {
+ (*a_num)++;
+ }
+ }
+ }
+
+ return total;
+}
+
+static DNS_ERROR dns_lookup(TALLOC_CTX *mem_ctx, const char* name,
+ uint16_t q_type, struct dns_request **reply)
+{
+ int len, rlen;
+ uint8_t *answer;
+ bool loop;
+ struct dns_buffer buf;
+ DNS_ERROR err;
+
+ /* give space for a good sized answer by default */
+ answer = NULL;
+ len = 1500;
+ do {
+ answer = talloc_realloc(mem_ctx, answer, uint8_t, len);
+ if (!answer) {
+ return ERROR_DNS_NO_MEMORY;
+ }
+ rlen = res_search(name, DNS_CLASS_IN, q_type, answer, len);
+ if (rlen == -1) {
+ if (len >= 65535) {
+ return ERROR_DNS_SOCKET_ERROR;
+ }
+ /* retry once with max packet size */
+ len = 65535;
+ loop = true;
+ } else if (rlen > len) {
+ len = rlen;
+ loop = true;
+ } else {
+ loop = false;
+ }
+ } while(loop);
+
+ buf.data = answer;
+ buf.size = rlen;
+ buf.offset = 0;
+ buf.error = ERROR_DNS_SUCCESS;
+
+ err = dns_unmarshall_request(mem_ctx, &buf, reply);
+
+ TALLOC_FREE(answer);
+ return err;
+}
+
+static struct dns_records_container get_a_aaaa_records(TALLOC_CTX *mem_ctx,
+ const char* name,
+ int port)
+{
+ struct dns_request *reply;
+ struct dns_records_container ret;
+ char **addrs = NULL;
+ uint32_t a_num, total;
+ uint16_t qtype;
+ TALLOC_CTX *tmp_ctx;
+ DNS_ERROR err;
+
+ memset(&ret, 0, sizeof(struct dns_records_container));
+
+ tmp_ctx = talloc_new(mem_ctx);
+ if (!tmp_ctx) {
+ return ret;
+ }
+
+ qtype = QTYPE_AAAA;
+
+ /* this is the blocking call we are going to lots of trouble
+ to avoid them in the parent */
+ err = dns_lookup(tmp_ctx, name, qtype, &reply);
+ if (!ERR_DNS_IS_OK(err)) {
+ qtype = QTYPE_A;
+ err = dns_lookup(tmp_ctx, name, qtype, &reply);
+ if (!ERR_DNS_IS_OK(err)) {
+ goto done;
+ }
+ }
+
+ a_num = total = 0;
+ total = reply_to_addrs(tmp_ctx, &a_num, &addrs, total, reply, port);
+
+ if (qtype == QTYPE_AAAA && a_num == 0) {
+ /*
+ * DNS server didn't returned A when asked for AAAA records.
+ * Most of the server do it, let's ask for A specificaly.
+ */
+ err = dns_lookup(tmp_ctx, name, QTYPE_A, &reply);
+ if (ERR_DNS_IS_OK(err)) {
+ /*
+ * Ignore an error here and just return any AAAA
+ * records we already got. This may be an IPv6-only
+ * config.
+ */
+ total = reply_to_addrs(tmp_ctx, &a_num, &addrs, total,
+ reply, port);
+ }
+ }
+
+ if (total) {
+ talloc_steal(mem_ctx, addrs);
+ ret.count = total;
+ ret.list = addrs;
+ }
+
+done:
+ TALLOC_FREE(tmp_ctx);
+ return ret;
+}
+
+static struct dns_records_container get_srv_records(TALLOC_CTX *mem_ctx,
+ const char* name)
+{
+ struct dns_records_container ret = {0};
+ char **addrs = NULL;
+ struct dns_rr_srv *dclist;
+ NTSTATUS status;
+ size_t total;
+ size_t i;
+ size_t count = 0;
+
+ memset(&ret, 0, sizeof(struct dns_records_container));
+ /* this is the blocking call we are going to lots of trouble
+ to avoid them in the parent */
+ status = ads_dns_lookup_srv(mem_ctx, name, &dclist, &count);
+ if (!NT_STATUS_IS_OK(status)) {
+ return ret;
+ }
+ total = 0;
+ if (count == 0) {
+ return ret;
+ }
+
+ /* Loop over all returned records and pick the records */
+ for (i = 0; i < count; i++) {
+ struct dns_records_container c;
+ const char* tmp_str;
+
+ tmp_str = dclist[i].hostname;
+ if (strchr(tmp_str, '.') && tmp_str[strlen(tmp_str)-1] != '.') {
+ /* we are asking for a fully qualified name, but the
+ name doesn't end in a '.'. We need to prevent the
+ DNS library trying the search domains configured in
+ resolv.conf */
+ tmp_str = talloc_asprintf(mem_ctx, "%s.", tmp_str);
+ }
+
+ c = get_a_aaaa_records(mem_ctx, tmp_str, dclist[i].port);
+
+ /* wrap check */
+ if (total + c.count < total) {
+ /* possibly could just break here instead? */
+ TALLOC_FREE(addrs);
+ return ret;
+ }
+ total += c.count;
+ if (addrs == NULL) {
+ addrs = c.list;
+ } else {
+ unsigned j;
+
+ addrs = talloc_realloc(mem_ctx, addrs, char*, total);
+ for (j=0; j < c.count; j++) {
+ addrs[total - j - 1] = talloc_steal(addrs, c.list[j]);
+ }
+ }
+ }
+
+ if (total) {
+ ret.count = total;
+ ret.list = addrs;
+ }
+
+ return ret;
+}
+/*
+ the blocking child
+*/
+static void run_child_dns_lookup(struct dns_ex_state *state, int fd)
+{
+ bool first;
+ bool do_srv = (state->flags & RESOLVE_NAME_FLAG_DNS_SRV);
+ struct dns_records_container c;
+ char* addrs = NULL;
+ unsigned int i;
+
+ if (strchr(state->name.name, '.') && state->name.name[strlen(state->name.name)-1] != '.') {
+ /* we are asking for a fully qualified name, but the
+ name doesn't end in a '.'. We need to prevent the
+ DNS library trying the search domains configured in
+ resolv.conf */
+ state->name.name = talloc_strdup_append(discard_const_p(char, state->name.name),
+ ".");
+ }
+
+
+ if (do_srv) {
+ c = get_srv_records(state, state->name.name);
+ } else {
+ c = get_a_aaaa_records(state, state->name.name, state->port);
+ }
+
+ /* This line in critical - if we return without writing to the
+ * pipe, this is the signal that the name did not exist */
+ if (c.count == 0) {
+ goto done;
+ }
+
+ addrs = talloc_strdup(state, "");
+ if (!addrs) {
+ goto done;
+ }
+ first = true;
+
+ for (i=0; i < c.count; i++) {
+ addrs = talloc_asprintf_append_buffer(addrs, "%s%s",
+ first?"":",",
+ c.list[i]);
+ first = false;
+ }
+
+ if (addrs) {
+ DEBUG(11, ("Addrs = %s\n", addrs));
+ sys_write_v(fd, addrs, talloc_get_size(addrs));
+ }
+
+done:
+ close(fd);
+}
+
+/*
+ the blocking child
+*/
+static void run_child_getaddrinfo(struct dns_ex_state *state, int fd)
+{
+ int ret;
+ struct addrinfo hints;
+ struct addrinfo *res;
+ struct addrinfo *res_list = NULL;
+ char *addrs;
+ bool first;
+
+ ZERO_STRUCT(hints);
+ hints.ai_socktype = SOCK_STREAM;
+ hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
+
+ ret = getaddrinfo(state->name.name, "0", &hints, &res_list);
+ /* try to fallback in case of error */
+ if (state->do_fallback) {
+ switch (ret) {
+#ifdef EAI_NODATA
+ case EAI_NODATA:
+#endif
+ case EAI_FAIL:
+ /* Linux returns EAI_NODATA on non-RFC1034-compliant names. FreeBSD returns EAI_FAIL */
+ case EAI_NONAME:
+ /* getaddrinfo() doesn't handle CNAME or non-RFC1034 compatible records */
+ run_child_dns_lookup(state, fd);
+ return;
+ default:
+ break;
+ }
+ }
+ if (ret != 0) {
+ goto done;
+ }
+
+ addrs = talloc_strdup(state, "");
+ if (!addrs) {
+ goto done;
+ }
+ first = true;
+ for (res = res_list; res; res = res->ai_next) {
+ char addrstr[INET6_ADDRSTRLEN];
+ if (!print_sockaddr_len(addrstr, sizeof(addrstr), (struct sockaddr *)res->ai_addr, res->ai_addrlen)) {
+ continue;
+ }
+ addrs = talloc_asprintf_append_buffer(addrs, "%s%s@%u/%s",
+ first?"":",",
+ addrstr,
+ state->port,
+ state->name.name);
+ if (!addrs) {
+ goto done;
+ }
+ first = false;
+ }
+
+ if (addrs) {
+ sys_write_v(fd, addrs, talloc_get_size(addrs));
+ }
+done:
+ if (res_list) {
+ freeaddrinfo(res_list);
+ }
+ close(fd);
+}
+
+/*
+ handle a read event on the pipe
+*/
+static void pipe_handler(struct tevent_context *ev, struct tevent_fd *fde,
+ uint16_t flags, void *private_data)
+{
+ struct composite_context *c = talloc_get_type(private_data, struct composite_context);
+ struct dns_ex_state *state = talloc_get_type(c->private_data,
+ struct dns_ex_state);
+ char *address;
+ uint32_t num_addrs, i;
+ char **addrs;
+ int ret;
+ int status;
+ int value = 0;
+
+ /* if we get any event from the child then we know that we
+ won't need to kill it off */
+ talloc_set_destructor(state, NULL);
+
+ if (ioctl(state->child_fd, FIONREAD, &value) != 0) {
+ value = 8192;
+ }
+
+ address = talloc_array(state, char, value+1);
+ if (address) {
+ /* yes, we don't care about EAGAIN or other niceities
+ here. They just can't happen with this parent/child
+ relationship, and even if they did then giving an error is
+ the right thing to do */
+ ret = read(state->child_fd, address, value);
+ } else {
+ ret = -1;
+ }
+ if (waitpid(state->child, &status, WNOHANG) == 0) {
+ kill(state->child, SIGKILL);
+ waitpid(state->child, &status, 0);
+ }
+
+ if (ret <= 0) {
+ /* The check for ret == 0 here is important, if the
+ * name does not exist, then no bytes are written to
+ * the pipe */
+ DEBUG(3,("dns child failed to find name '%s' of type %s\n",
+ state->name.name, (state->flags & RESOLVE_NAME_FLAG_DNS_SRV)?"SRV":"A"));
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return;
+ }
+
+ /* ensure the address looks good */
+ address[ret] = 0;
+
+ addrs = str_list_make(state, address, ",");
+ if (composite_nomem(addrs, c)) return;
+
+ num_addrs = str_list_length((const char * const *)addrs);
+
+ state->addrs = talloc_array(state, struct socket_address *,
+ num_addrs+1);
+ if (composite_nomem(state->addrs, c)) return;
+
+ state->names = talloc_array(state, char *, num_addrs+1);
+ if (composite_nomem(state->names, c)) return;
+
+ for (i=0; i < num_addrs; i++) {
+ uint32_t port = 0;
+ char *p = strrchr(addrs[i], '@');
+ char *n;
+ int error = 0;
+
+ if (!p) {
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return;
+ }
+
+ *p = '\0';
+ p++;
+
+ n = strrchr(p, '/');
+ if (!n) {
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return;
+ }
+
+ *n = '\0';
+ n++;
+
+ if (strcmp(addrs[i], "0.0.0.0") == 0) {
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return;
+ }
+ port = smb_strtoul(p, NULL, 10, &error, SMB_STR_STANDARD);
+ if (port > UINT16_MAX || error != 0) {
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return;
+ }
+ state->addrs[i] = socket_address_from_strings(state->addrs,
+ "ip",
+ addrs[i],
+ port);
+ if (composite_nomem(state->addrs[i], c)) return;
+
+ state->names[i] = talloc_strdup(state->names, n);
+ if (composite_nomem(state->names[i], c)) return;
+ }
+ state->addrs[i] = NULL;
+ state->names[i] = NULL;
+
+ composite_done(c);
+}
+
+/*
+ getaddrinfo() or dns_lookup() name resolution method - async send
+ */
+struct composite_context *resolve_name_dns_ex_send(TALLOC_CTX *mem_ctx,
+ struct tevent_context *event_ctx,
+ void *privdata,
+ uint32_t flags,
+ uint16_t port,
+ struct nbt_name *name,
+ bool do_fallback)
+{
+ struct composite_context *c;
+ struct dns_ex_state *state;
+ int fd[2] = { -1, -1 };
+ int ret;
+
+ c = composite_create(mem_ctx, event_ctx);
+ if (c == NULL) return NULL;
+
+ if (flags & RESOLVE_NAME_FLAG_FORCE_NBT) {
+ composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+ return c;
+ }
+
+ state = talloc_zero(c, struct dns_ex_state);
+ if (composite_nomem(state, c)) return c;
+ c->private_data = state;
+
+ c->status = nbt_name_dup(state, name, &state->name);
+ if (!composite_is_ok(c)) return c;
+
+ /* setup a pipe to chat to our child */
+ ret = pipe(fd);
+ if (ret == -1) {
+ composite_error(c, map_nt_error_from_unix_common(errno));
+ return c;
+ }
+
+ state->do_fallback = do_fallback;
+ state->flags = flags;
+ state->port = port;
+
+ state->child_fd = fd[0];
+ state->event_ctx = c->event_ctx;
+
+ /* we need to put the child in our event context so
+ we know when the dns_lookup() has finished */
+ state->fde = tevent_add_fd(c->event_ctx, c, state->child_fd, TEVENT_FD_READ,
+ pipe_handler, c);
+ if (composite_nomem(state->fde, c)) {
+ close(fd[0]);
+ close(fd[1]);
+ return c;
+ }
+ tevent_fd_set_auto_close(state->fde);
+
+ state->child = fork();
+ if (state->child == (pid_t)-1) {
+ composite_error(c, map_nt_error_from_unix_common(errno));
+ return c;
+ }
+
+ if (state->child == 0) {
+ close(fd[0]);
+ if (state->flags & RESOLVE_NAME_FLAG_FORCE_DNS) {
+ run_child_dns_lookup(state, fd[1]);
+ } else {
+ run_child_getaddrinfo(state, fd[1]);
+ }
+ _exit(0);
+ }
+ close(fd[1]);
+
+ /* cleanup wayward children */
+ talloc_set_destructor(state, dns_ex_destructor);
+
+ return c;
+}
+
+/*
+ getaddrinfo() or dns_lookup() name resolution method - recv side
+*/
+NTSTATUS resolve_name_dns_ex_recv(struct composite_context *c,
+ TALLOC_CTX *mem_ctx,
+ struct socket_address ***addrs,
+ char ***names)
+{
+ NTSTATUS status;
+
+ status = composite_wait(c);
+
+ if (NT_STATUS_IS_OK(status)) {
+ struct dns_ex_state *state = talloc_get_type(c->private_data,
+ struct dns_ex_state);
+ *addrs = talloc_steal(mem_ctx, state->addrs);
+ if (names) {
+ *names = talloc_steal(mem_ctx, state->names);
+ }
+ }
+
+ talloc_free(c);
+ return status;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-23 19:31:57 +0000