diff options
Diffstat (limited to 'src/resolv')
| -rw-r--r-- | src/resolv/async_resolv.c | 2626 | ||||
| -rw-r--r-- | src/resolv/async_resolv.h | 230 | ||||
| -rw-r--r-- | src/resolv/async_resolv_utils.c | 343 |
3 files changed, 3199 insertions, 0 deletions
diff --git a/src/resolv/async_resolv.c b/src/resolv/async_resolv.c new file mode 100644 index 0000000..6b3a8ce --- /dev/null +++ b/src/resolv/async_resolv.c @@ -0,0 +1,2626 @@ +/* + SSSD + + Async resolver + + Authors: + Martin Nagy <mnagy@redhat.com> + Jakub Hrozek <jhrozek@redhat.com> + + Copyright (C) Red Hat, Inc 2009 + + 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/>. +*/ + +#include <sys/select.h> +#include <arpa/inet.h> +#include <arpa/nameser.h> + +#include <ares.h> +#include <talloc.h> +#include <tevent.h> + +#include <errno.h> +#include <netdb.h> +#include <stddef.h> +#include <string.h> +#include <unistd.h> +#include <limits.h> + +#include "config.h" +#include "resolv/async_resolv.h" +#include "util/dlinklist.h" +#include "util/util.h" + +#define DNS__16BIT(p) (((p)[0] << 8) | (p)[1]) + +/* + * Macro DNS__32BIT reads a network long (32 bit) given in network + * byte order, and returns its value as an unsigned int. Copied + * from c-ares source code. + */ +#define DNS__32BIT(p) ((unsigned int) \ + (((unsigned int)((unsigned char)(p)[0]) << 24U) | \ + ((unsigned int)((unsigned char)(p)[1]) << 16U) | \ + ((unsigned int)((unsigned char)(p)[2]) << 8U) | \ + ((unsigned int)((unsigned char)(p)[3])))) + +#define DNS_HEADER_ANCOUNT(h) DNS__16BIT((h) + 6) +#define DNS_RR_LEN(r) DNS__16BIT((r) + 8) +#define DNS_RR_TTL(r) DNS__32BIT((r) + 4) + +enum host_database default_host_dbs[] = { DB_FILES, DB_DNS, DB_SENTINEL }; + +struct fd_watch { + struct fd_watch *prev; + struct fd_watch *next; + + int fd; + struct resolv_ctx *ctx; + struct tevent_fd *fde; +}; + +struct resolv_ctx { + struct tevent_context *ev_ctx; + ares_channel channel; + + /* List of file descriptors that are watched by tevent. */ + struct fd_watch *fds; + + /* Time in milliseconds before canceling a DNS request */ + int timeout; + + /* Time in milliseconds for communication with single DNS server. */ + int ares_timeout; + + /* Use search list from resolv.conf and perform DNS search if needed. */ + bool use_search_list; + + /* The timeout watcher periodically calls ares_process_fd() to check + * if our pending requests didn't timeout. */ + int pending_requests; + struct tevent_timer *timeout_watcher; +}; + +struct request_watch { + struct tevent_req *req; + struct resolv_request *rr; +}; + +struct resolv_request { + struct resolv_ctx *ctx; + struct request_watch *rwatch; + struct tevent_timer *request_timeout; +}; + +static int +return_code(int ares_code) +{ + switch (ares_code) { + case ARES_SUCCESS: + return EOK; + case ARES_ENOMEM: + return ENOMEM; + case ARES_EFILE: + default: + return EIO; + } +} + +const char * +resolv_strerror(int ares_code) +{ + return ares_strerror(ares_code); +} + +static int +fd_watch_destructor(struct fd_watch *f) +{ + DLIST_REMOVE(f->ctx->fds, f); + f->fd = -1; + + return 0; +} + +static void +fd_input_available(struct tevent_context *ev, struct tevent_fd *fde, + uint16_t flags, void *data) +{ + struct fd_watch *watch = talloc_get_type(data, struct fd_watch); + + if (watch->ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + return; + } + + ares_process_fd(watch->ctx->channel, + flags & TEVENT_FD_READ ? watch->fd : ARES_SOCKET_BAD, + flags & TEVENT_FD_WRITE ? watch->fd : ARES_SOCKET_BAD); +} + +static void +check_fd_timeouts(struct tevent_context *ev, struct tevent_timer *te, + struct timeval current_time, void *private_data); + +static void +add_timeout_timer(struct tevent_context *ev, struct resolv_ctx *ctx) +{ + struct timeval tv = { 0, 0 }; + struct timeval *tvp; + + if (ctx->timeout_watcher) { + return; + } + + tvp = ares_timeout(ctx->channel, NULL, &tv); + + if (tvp == NULL) { + tvp = &tv; + } + + /* Enforce a minimum of 1 second. */ + if (tvp->tv_sec < 1) { + tv = tevent_timeval_current_ofs(1, 0); + } else { + tv = tevent_timeval_current_ofs(tvp->tv_sec, tvp->tv_usec); + } + + ctx->timeout_watcher = tevent_add_timer(ev, ctx, tv, check_fd_timeouts, + ctx); + if (ctx->timeout_watcher == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "tevent_add_timer() failed\n"); + } +} + +static void +check_fd_timeouts(struct tevent_context *ev, struct tevent_timer *te, + struct timeval current_time, void *private_data) +{ + struct resolv_ctx *ctx = talloc_get_type(private_data, struct resolv_ctx); + + DEBUG(SSSDBG_TRACE_ALL, "Checking for DNS timeouts\n"); + + /* NULLify the timeout_watcher so we don't + * free it in the _done() function if it + * gets called. Now that we're already in + * the handler, tevent will take care of + * freeing it when it returns. + */ + ctx->timeout_watcher = NULL; + + ares_process_fd(ctx->channel, ARES_SOCKET_BAD, ARES_SOCKET_BAD); + + if (ctx->pending_requests > 0) { + add_timeout_timer(ev, ctx); + } +} + +static void +resolv_request_timeout(struct tevent_context *ev, + struct tevent_timer *te, + struct timeval tv, void *pvt) +{ + struct resolv_request *rreq; + + DEBUG(SSSDBG_MINOR_FAILURE, "The resolve request timed out\n"); + + rreq = talloc_get_type(pvt, struct resolv_request); + if (rreq->rwatch == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "The request already completed\n"); + return; + } + + tevent_req_error(rreq->rwatch->req, ETIMEDOUT); + rreq->rwatch = NULL; +} + +static int +request_watch_destructor(struct request_watch *rwatch) +{ + DEBUG(SSSDBG_TRACE_FUNC, "Deleting request watch\n"); + if (rwatch->rr) rwatch->rr->rwatch = NULL; + return 0; +} + +static struct resolv_request * +schedule_request_timeout(struct tevent_context *ev, struct resolv_ctx *ctx, + struct tevent_req *req) +{ + struct resolv_request *rreq; + struct timeval tv; + + DEBUG(SSSDBG_TRACE_INTERNAL, "Scheduling a timeout of %d seconds\n", + ctx->timeout); + tv = tevent_timeval_current_ofs(ctx->timeout, 0); + + /* Intentionally allocating on ctx, because the request might go away + * before c-ares returns */ + rreq = talloc(ctx, struct resolv_request); + if (!rreq) { + talloc_zfree(req); + return NULL; + } + rreq->ctx = ctx; + rreq->request_timeout = tevent_add_timer(ev, rreq, tv, + resolv_request_timeout, + rreq); + if (rreq->request_timeout == NULL) { + talloc_free(rreq); + return NULL; + } + + /* The watch will go away when the request finishes */ + rreq->rwatch = talloc(req, struct request_watch); + if (!rreq->rwatch) { + talloc_zfree(req); + return NULL; + } + + rreq->rwatch->req = req; + rreq->rwatch->rr = rreq; + talloc_set_destructor(rreq->rwatch, request_watch_destructor); + + return rreq; +} + +static struct resolv_request * +schedule_timeout_watcher(struct tevent_context *ev, struct resolv_ctx *ctx, + struct tevent_req *req) +{ + struct resolv_request *rreq; + + rreq = schedule_request_timeout(ev, ctx, req); + if (!rreq) return NULL; + + ctx->pending_requests++; + + DEBUG(SSSDBG_TRACE_INTERNAL, "Scheduling DNS timeout watcher\n"); + add_timeout_timer(ev, ctx); + return rreq; +} + +static void +unschedule_timeout_watcher(struct resolv_ctx *ctx, struct resolv_request *rreq) +{ + /* Unlink the watch if the request is still active */ + if (rreq->rwatch) { + rreq->rwatch->rr = NULL; + } + talloc_free(rreq); /* Cancels the tevent timeout as well */ + + if (ctx->pending_requests <= 0) { + DEBUG(SSSDBG_CRIT_FAILURE, "Pending DNS requests mismatch\n"); + return; + } + + ctx->pending_requests--; + if (ctx->pending_requests == 0) { + DEBUG(SSSDBG_TRACE_ALL, "Unscheduling DNS timeout watcher\n"); + talloc_zfree(ctx->timeout_watcher); + } +} + +static void fd_event_add(struct resolv_ctx *ctx, int s, int flags); +static void fd_event_close(struct resolv_ctx *ctx, int s); + +/* + * When ares is ready to read or write to a file descriptor, it will + * call this callback. If both read and write are 0, it means that ares + * will soon close the socket. We are mainly using this function to register + * new file descriptors with tevent. + */ +static void +fd_event(void *data, int s, int fd_read, int fd_write) +{ + struct resolv_ctx *ctx = talloc_get_type(data, struct resolv_ctx); + struct fd_watch *watch; + int flags; + + /* The socket is about to get closed. */ + if (fd_read == 0 && fd_write == 0) { + fd_event_close(ctx, s); + return; + } + + flags = fd_read ? TEVENT_FD_READ : 0; + flags |= fd_write ? TEVENT_FD_WRITE : 0; + + /* Are we already watching this file descriptor? */ + watch = ctx->fds; + while (watch) { + if (watch->fd == s) { + tevent_fd_set_flags(watch->fde, flags); + return; + } + watch = watch->next; + } + + fd_event_add(ctx, s, flags); +} + +static void +fd_event_add(struct resolv_ctx *ctx, int s, int flags) +{ + struct fd_watch *watch; + + /* The file descriptor is new, register it with tevent. */ + watch = talloc(ctx, struct fd_watch); + if (watch == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Out of memory allocating fd_watch structure\n"); + return; + } + talloc_set_destructor(watch, fd_watch_destructor); + + watch->fd = s; + watch->ctx = ctx; + + watch->fde = tevent_add_fd(ctx->ev_ctx, watch, s, flags, + fd_input_available, watch); + if (watch->fde == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "tevent_add_fd() failed\n"); + talloc_free(watch); + return; + } + DLIST_ADD(ctx->fds, watch); +} + +static void +fd_event_close(struct resolv_ctx *ctx, int s) +{ + struct fd_watch *watch; + + /* Remove the socket from list */ + watch = ctx->fds; + while (watch) { + if (watch->fd == s) { + talloc_free(watch); + return; + } + watch = watch->next; + } +} + +static int +resolv_ctx_destructor(struct resolv_ctx *ctx) +{ + ares_channel channel; + + if (ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "Ares channel already destroyed?\n"); + return -1; + } + + /* Set ctx->channel to NULL first, so that callbacks that get + * ARES_EDESTRUCTION won't retry. */ + channel = ctx->channel; + ctx->channel = NULL; + ares_destroy(channel); + + return 0; +} + +static int +recreate_ares_channel(struct resolv_ctx *ctx) +{ + int ret; + ares_channel new_channel; + ares_channel old_channel; + struct ares_options options; + + DEBUG(SSSDBG_CONF_SETTINGS, "Initializing new c-ares channel\n"); + /* FIXME: the options would contain + * the nameservers to contact, the domains + * to search... => get from confdb + */ + options.sock_state_cb = fd_event; + options.sock_state_cb_data = ctx; + options.timeout = ctx->ares_timeout; + /* Only affects ares_gethostbyname */ + options.lookups = discard_const("f"); + options.tries = 1; + options.flags = 0; + if (ctx->use_search_list == false) { + options.flags |= ARES_FLAG_NOSEARCH; + } + + ret = ares_init_options(&new_channel, &options, + ARES_OPT_SOCK_STATE_CB | + ARES_OPT_TIMEOUTMS | + ARES_OPT_LOOKUPS | + ARES_OPT_TRIES | + ARES_OPT_FLAGS); + if (ret != ARES_SUCCESS) { + DEBUG(SSSDBG_CRIT_FAILURE, "Failed to initialize ares channel: %s\n", + resolv_strerror(ret)); + return return_code(ret); + } + + old_channel = ctx->channel; + ctx->channel = new_channel; + if (old_channel != NULL) { + DEBUG(SSSDBG_CONF_SETTINGS, "Destroying the old c-ares channel\n"); + ares_destroy(old_channel); + } + + return EOK; +} + +int +resolv_init(TALLOC_CTX *mem_ctx, struct tevent_context *ev_ctx, + int timeout, int ares_timeout, bool use_search_list, + struct resolv_ctx **ctxp) +{ + int ret; + struct resolv_ctx *ctx; + + if (timeout < 1) { + DEBUG(SSSDBG_MINOR_FAILURE, + "The timeout is too short, DNS operations are going to fail. " + "This is a bug outside unit tests\n"); + } + + ctx = talloc_zero(mem_ctx, struct resolv_ctx); + if (ctx == NULL) + return ENOMEM; + + ctx->ev_ctx = ev_ctx; + ctx->timeout = timeout; + ctx->ares_timeout = ares_timeout; + ctx->use_search_list = use_search_list; + + ret = recreate_ares_channel(ctx); + if (ret != EOK) { + goto done; + } + + talloc_set_destructor(ctx, resolv_ctx_destructor); + + *ctxp = ctx; + return EOK; + +done: + talloc_free(ctx); + return ret; +} + +void +resolv_reread_configuration(struct resolv_ctx *ctx) +{ + recreate_ares_channel(ctx); +} + +static errno_t +resolv_copy_in_addr(TALLOC_CTX *mem_ctx, struct resolv_addr *ret, + struct ares_addrttl *attl) +{ + ret->ipaddr = talloc_array(mem_ctx, uint8_t, sizeof(struct in_addr)); + if (!ret->ipaddr) return ENOMEM; + + memcpy(ret->ipaddr, &attl->ipaddr, sizeof(struct in_addr)); + ret->ttl = attl->ttl; + + return EOK; +} + +static errno_t +resolv_copy_in6_addr(TALLOC_CTX *mem_ctx, struct resolv_addr *ret, + struct ares_addr6ttl *a6ttl) +{ + ret->ipaddr = talloc_array(mem_ctx, uint8_t, sizeof(struct in6_addr)); + if (!ret->ipaddr) return ENOMEM; + + memcpy(ret->ipaddr, &a6ttl->ip6addr, sizeof(struct in6_addr)); + ret->ttl = a6ttl->ttl; + + return EOK; +} + +static struct resolv_hostent * +resolv_copy_hostent_common(TALLOC_CTX *mem_ctx, struct hostent *src) +{ + struct resolv_hostent *ret; + int len; + int i; + + ret = talloc_zero(mem_ctx, struct resolv_hostent); + if (ret == NULL) { + return NULL; + } + + if (src->h_name != NULL) { + ret->name = talloc_strdup(ret, src->h_name); + if (ret->name == NULL) { + goto fail; + } + } + if (src->h_aliases != NULL) { + for (len = 0; src->h_aliases[len] != NULL; len++); + + ret->aliases = talloc_array(ret, char *, len + 1); + if (ret->aliases == NULL) { + goto fail; + } + + for (i = 0; i < len; i++) { + ret->aliases[i] = talloc_strdup(ret->aliases, src->h_aliases[i]); + if (ret->aliases[i] == NULL) { + goto fail; + } + } + ret->aliases[len] = NULL; + } + + ret->family = src->h_addrtype; + return ret; + +fail: + talloc_free(ret); + return NULL; +} + +struct resolv_hostent * +resolv_copy_hostent(TALLOC_CTX *mem_ctx, struct hostent *src) +{ + struct resolv_hostent *ret; + int len; + int i; + + ret = resolv_copy_hostent_common(mem_ctx, src); + if (ret == NULL) { + return NULL; + } + + if (src->h_addr_list != NULL) { + for (len = 0; src->h_addr_list[len] != NULL; len++); + + ret->addr_list = talloc_array(ret, struct resolv_addr *, len + 1); + if (ret->addr_list == NULL) { + goto fail; + } + + for (i = 0; i < len; i++) { + ret->addr_list[i] = talloc_zero(ret->addr_list, + struct resolv_addr); + if (ret->addr_list[i] == NULL) { + goto fail; + } + + ret->addr_list[i]->ipaddr = talloc_memdup(ret->addr_list[i], + src->h_addr_list[i], + src->h_length); + if (ret->addr_list[i]->ipaddr == NULL) { + goto fail; + } + ret->addr_list[i]->ttl = RESOLV_DEFAULT_TTL; + } + ret->addr_list[len] = NULL; + } + return ret; + +fail: + talloc_free(ret); + return NULL; +} + +struct resolv_hostent * +resolv_copy_hostent_ares(TALLOC_CTX *mem_ctx, struct hostent *src, + int family, void *ares_ttl_data, + int num_ares_ttl_data) +{ + struct resolv_hostent *ret; + errno_t cret; + int i; + + ret = resolv_copy_hostent_common(mem_ctx, src); + if (ret == NULL) { + return NULL; + } + + if (num_ares_ttl_data > 0) { + ret->addr_list = talloc_array(ret, struct resolv_addr *, + num_ares_ttl_data + 1); + if (ret->addr_list == NULL) { + goto fail; + } + + for (i = 0; i < num_ares_ttl_data; i++) { + ret->addr_list[i] = talloc_zero(ret->addr_list, + struct resolv_addr); + if (ret->addr_list[i] == NULL) { + goto fail; + } + + switch (family) { + case AF_INET: + cret = resolv_copy_in_addr(ret->addr_list, ret->addr_list[i], + &((struct ares_addrttl *) ares_ttl_data)[i]); + break; + case AF_INET6: + cret = resolv_copy_in6_addr(ret->addr_list, ret->addr_list[i], + &((struct ares_addr6ttl *) ares_ttl_data)[i]); + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, + "Unknown address family %d\n", family); + goto fail; + } + + if (cret != EOK) { + DEBUG(SSSDBG_CRIT_FAILURE, "Could not copy address\n"); + goto fail; + } + } + ret->addr_list[num_ares_ttl_data] = NULL; + } + + ret->family = family; + return ret; + +fail: + talloc_free(ret); + return NULL; +} + +/* =================== Resolve host name in files =========================*/ +struct gethostbyname_files_state { + struct resolv_ctx *resolv_ctx; + + /* Part of the query. */ + const char *name; + int family; + + /* query result */ + struct resolv_hostent *rhostent; + + /* returned by ares. */ + int status; +}; + +/* Fake up an async interface even though files would + * always be blocking */ +static struct tevent_req * +resolv_gethostbyname_files_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + const char *name, + int family) +{ + struct tevent_req *req; + struct gethostbyname_files_state *state; + struct hostent *hostent = NULL; + + req = tevent_req_create(mem_ctx, &state, + struct gethostbyname_files_state); + if (req == NULL) { + return NULL; + } + + state->resolv_ctx = ctx; + state->name = name; + state->rhostent = NULL; + state->family = family; + + DEBUG(SSSDBG_CONF_SETTINGS, + "Trying to resolve %s record of '%s' in files\n", + state->family == AF_INET ? "A" : "AAAA", state->name); + + state->status = ares_gethostbyname_file(state->resolv_ctx->channel, + state->name, state->family, + &hostent); + + if (state->status == ARES_SUCCESS) { + state->rhostent = resolv_copy_hostent(state, hostent); + if (state->rhostent == NULL) { + tevent_req_error(req, ENOMEM); + goto done; + } + } else if (state->status == ARES_ENOTFOUND || + state->status == ARES_ENODATA) { + /* Just say we didn't find anything and let the caller decide + * about retrying */ + tevent_req_error(req, ENOENT); + goto done; + } else { + tevent_req_error(req, return_code(state->status)); + goto done; + } + + tevent_req_done(req); +done: + if (hostent) ares_free_hostent(hostent); + tevent_req_post(req, ev); + return req; +} + +static errno_t +resolv_gethostbyname_files_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx, + int *status, struct resolv_hostent **rhostent) +{ + struct gethostbyname_files_state *state = tevent_req_data(req, + struct gethostbyname_files_state); + + /* Fill in even in case of error as status contains the + * c-ares return code */ + if (status) { + *status = state->status; + } + if (rhostent) { + *rhostent = talloc_steal(mem_ctx, state->rhostent); + } + + TEVENT_REQ_RETURN_ON_ERROR(req); + + return EOK; +} + +/* ==================== Resolve host name in DNS =========================*/ +struct gethostbyname_dns_state { + struct resolv_ctx *resolv_ctx; + struct tevent_context *ev; + + /* Part of the query. */ + const char *name; + int family; + + /* query result */ + struct resolv_hostent *rhostent; + + /* These are returned by ares. */ + int status; + int timeouts; + int retrying; +}; + +static void +resolv_gethostbyname_dns_wakeup(struct tevent_req *subreq); +static void +resolv_gethostbyname_dns_query(struct tevent_req *req, + struct gethostbyname_dns_state *state); +static void +resolv_gethostbyname_dns_query_done(void *arg, int status, int timeouts, + unsigned char *abuf, int alen); +static int +resolv_gethostbyname_dns_parse(struct gethostbyname_dns_state *state, + int status, unsigned char *abuf, int alen); + +static struct tevent_req * +resolv_gethostbyname_dns_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + struct resolv_ctx *ctx, const char *name, + int family) +{ + struct tevent_req *req, *subreq; + struct gethostbyname_dns_state *state; + struct timeval tv = { 0, 0 }; + + if (ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + return NULL; + } + + req = tevent_req_create(mem_ctx, &state, struct gethostbyname_dns_state); + if (req == NULL) { + return NULL; + } + + state->resolv_ctx = ctx; + state->ev = ev; + state->name = name; + state->rhostent = NULL; + state->status = 0; + state->timeouts = 0; + state->retrying = 0; + state->family = family; + + /* We need to have a wrapper around ares async calls, because + * they can in some cases call it's callback immediately. + * This would not let our caller to set a callback for req. */ + subreq = tevent_wakeup_send(req, ev, tv); + if (subreq == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Failed to add critical timer to run next operation!\n"); + talloc_zfree(req); + return NULL; + } + tevent_req_set_callback(subreq, resolv_gethostbyname_dns_wakeup, req); + + return req; +} + +static void +resolv_gethostbyname_dns_wakeup(struct tevent_req *subreq) +{ + struct tevent_req *req = tevent_req_callback_data(subreq, + struct tevent_req); + struct gethostbyname_dns_state *state = tevent_req_data(req, + struct gethostbyname_dns_state); + + if (!tevent_wakeup_recv(subreq)) { + tevent_req_error(req, EIO); + return; + } + talloc_zfree(subreq); + + if (state->resolv_ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + tevent_req_error(req, EIO); + return; + } + + resolv_gethostbyname_dns_query(req, state); +} + +static void +resolv_gethostbyname_dns_query(struct tevent_req *req, + struct gethostbyname_dns_state *state) +{ + struct resolv_request *rreq; + + DEBUG(SSSDBG_CONF_SETTINGS, "Trying to resolve %s record of '%s' in DNS\n", + state->family == AF_INET ? "A" : "AAAA", state->name); + + rreq = schedule_timeout_watcher(state->ev, state->resolv_ctx, req); + if (!rreq) { + tevent_req_error(req, ENOMEM); + return; + } + + ares_search(state->resolv_ctx->channel, + state->name, ns_c_in, + (state->family == AF_INET) ? ns_t_a : ns_t_aaaa, + resolv_gethostbyname_dns_query_done, rreq); +} + +static void +resolv_gethostbyname_dns_query_done(void *arg, int status, int timeouts, + unsigned char *abuf, int alen) +{ + errno_t ret; + struct gethostbyname_dns_state *state; + struct resolv_request *rreq = talloc_get_type(arg, struct resolv_request); + struct tevent_req *req; + + + if (rreq->rwatch == NULL) { + /* The tevent request was cancelled while the ares call was still in + * progress so nobody cares about the result now. Quit. */ + unschedule_timeout_watcher(rreq->ctx, rreq); + return; + } + + req = rreq->rwatch->req; + unschedule_timeout_watcher(rreq->ctx, rreq); + + state = tevent_req_data(req, struct gethostbyname_dns_state); + + state->status = status; + state->timeouts = timeouts; + + /* If resolv.conf changed during processing of a request we might + * destroy the old channel before the request has a chance to finish. + * We must resend the request in this case */ + if (state->retrying == 0 && status == ARES_EDESTRUCTION + && state->resolv_ctx->channel != NULL) { + state->retrying = 1; + resolv_gethostbyname_dns_query(req, state); + return; + } + + if (status == ARES_ENOTFOUND || status == ARES_ENODATA) { + /* Just say we didn't find anything and let the caller decide + * about retrying */ + tevent_req_error(req, ENOENT); + return; + } + + if (status != ARES_SUCCESS) { + /* Any other error indicates a server error, + * so don't bother trying again + */ + tevent_req_error(req, return_code(status)); + return; + } + + ret = resolv_gethostbyname_dns_parse(state, status, abuf, alen); + if (ret != EOK) { + tevent_req_error(req, ret); + return; + } + + tevent_req_done(req); +} + +static int +resolv_gethostbyname_dns_parse(struct gethostbyname_dns_state *state, + int status, unsigned char *abuf, int alen) +{ + struct hostent *hostent = NULL; + int naddrttls; + errno_t ret; + void *addr = NULL; + + naddrttls = DNS_HEADER_ANCOUNT(abuf); + + switch (state->family) { + case AF_INET: + DEBUG(SSSDBG_TRACE_LIBS, "Parsing an A reply\n"); + + addr = talloc_array(state, struct ares_addrttl, naddrttls); + if (!addr) { + ret = ENOMEM; + goto fail; + } + + status = ares_parse_a_reply(abuf, alen, &hostent, + (struct ares_addrttl *) addr, + &naddrttls); + break; + case AF_INET6: + DEBUG(SSSDBG_TRACE_LIBS, "Parsing an AAAA reply\n"); + + addr = talloc_array(state, struct ares_addr6ttl, naddrttls); + if (!addr) { + ret = ENOMEM; + goto fail; + } + + status = ares_parse_aaaa_reply(abuf, alen, &hostent, + (struct ares_addr6ttl *) addr, + &naddrttls); + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, "Unknown family %d\n", state->family); + ret = EAFNOSUPPORT; + goto fail; + } + + if ((hostent != NULL) && (status == ARES_SUCCESS)) { + state->rhostent = resolv_copy_hostent_ares(state, hostent, + state->family, + addr, naddrttls); + ares_free_hostent(hostent); + if (state->rhostent == NULL) { + ret = ENOMEM; + goto fail; + } + + /* The address list is NULL. This is probably a bug in + * c-ares, but we need to handle it gracefully. + */ + if (state->rhostent->addr_list == NULL) { + talloc_zfree(state->rhostent); + return ENOENT; + } + } else if (status != ARES_SUCCESS) { + DEBUG(SSSDBG_OP_FAILURE, "Failed to parse reply: %d\n", status); + } else { + DEBUG(SSSDBG_CRIT_FAILURE, "NULL parse result!\n"); + } + + talloc_free(addr); + return return_code(status); + +fail: + talloc_free(addr); + return ret; +} + +static int +resolv_gethostbyname_dns_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx, + int *status, int *timeouts, + struct resolv_hostent **rhostent) +{ + struct gethostbyname_dns_state *state = tevent_req_data(req, + struct gethostbyname_dns_state); + + /* Fill in even in case of error as status contains the + * c-ares return code */ + if (status) { + *status = state->status; + } + if (timeouts) { + *timeouts = state->timeouts; + } + + TEVENT_REQ_RETURN_ON_ERROR(req); + + if (rhostent) { + *rhostent = talloc_steal(mem_ctx, state->rhostent); + } + + return EOK; +} + +/******************************************************************* + * Get host by name. * + *******************************************************************/ + +struct gethostbyname_state { + struct resolv_ctx *resolv_ctx; + struct tevent_context *ev; + + /* Part of the query. */ + const char *name; + int family; + + /* In which order to use IPv4, or v6 */ + enum restrict_family family_order; + + /* Known hosts databases and index to the current one */ + enum host_database *db; + int dbi; + + /* These are returned by ares. The hostent struct will be freed + * when the user callback returns. */ + struct resolv_hostent *rhostent; + int status; + int timeouts; + int retrying; +}; + +static errno_t +resolv_gethostbyname_unix(TALLOC_CTX *mem_ctx, const char *path, + struct resolv_hostent **_rhostent); +static errno_t +resolv_gethostbyname_address(TALLOC_CTX *mem_ctx, const char *address, + struct resolv_hostent **_rhostent); +static inline int +resolv_gethostbyname_family_init(enum restrict_family family_order); +static errno_t +resolv_gethostbyname_step(struct tevent_req *req); + +struct tevent_req * +resolv_gethostbyname_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + struct resolv_ctx *ctx, const char *name, + enum restrict_family family_order, + enum host_database *db) +{ + struct tevent_req *req; + struct gethostbyname_state *state; + errno_t ret; + + if (ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + return NULL; + } + + req = tevent_req_create(mem_ctx, &state, struct gethostbyname_state); + if (req == NULL) { + return NULL; + } + + state->resolv_ctx = ctx; + state->ev = ev; + state->name = talloc_strdup(state, name); + if (state->name == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "talloc_strdup() failed\n"); + goto fail; + } + + state->rhostent = NULL; + state->status = 0; + state->timeouts = 0; + state->retrying = 0; + state->family_order = family_order; + state->family = resolv_gethostbyname_family_init(state->family_order); + state->db = db; + state->dbi = 0; + + /* Do not attempt to resolve unix domain sockets */ + if (resolv_is_unix(state->name)) { + ret = resolv_gethostbyname_unix(state, state->name, + &state->rhostent); + if (ret != EOK) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Cannot create a fake hostent structure\n"); + goto fail; + } + + tevent_req_done(req); + tevent_req_post(req, ev); + return req; + } + + /* Do not attempt to resolve IP addresses */ + if (resolv_is_address(state->name)) { + ret = resolv_gethostbyname_address(state, state->name, + &state->rhostent); + if (ret != EOK) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Cannot create a fake hostent structure\n"); + goto fail; + } + + tevent_req_done(req); + tevent_req_post(req, ev); + return req; + } + + ret = resolv_gethostbyname_step(req); + if (ret != EOK) { + DEBUG(SSSDBG_CRIT_FAILURE, "Cannot start the resolving\n"); + goto fail; + } + + return req; + +fail: + talloc_zfree(req); + return NULL; +} + +bool +resolv_is_unix(const char *name) +{ + if (name && name[0] == '/') { + return 1; + } + DEBUG(SSSDBG_TRACE_ALL, + "[%s] does not look like a unix domain socket\n", name); + + return 0; +} + +bool +resolv_is_address(const char *name) +{ + struct addrinfo hints; + struct addrinfo *res = NULL; + int ret; + + memset((void *) &hints, 0, sizeof(struct addrinfo)); + hints.ai_family = AF_UNSPEC; + hints.ai_flags = AI_NUMERICHOST; /* No network lookups */ + + ret = getaddrinfo(name, NULL, &hints, &res); + if (ret != 0) { + if (ret == -2) { + DEBUG(SSSDBG_TRACE_ALL, + "[%s] does not look like an IP address\n", name); + } else { + DEBUG(SSSDBG_OP_FAILURE, "getaddrinfo failed [%d]: %s\n", + ret, gai_strerror(ret)); + } + } else { /* ret == 0 */ + freeaddrinfo(res); + } + + return ret == 0; +} + +static errno_t +resolv_gethostbyname_unix(TALLOC_CTX *mem_ctx, const char *path, + struct resolv_hostent **_rhostent) +{ + struct resolv_hostent *rhostent; + TALLOC_CTX *tmp_ctx; + errno_t ret; + + tmp_ctx = talloc_new(NULL); + if (!tmp_ctx) return ENOMEM; + + rhostent = talloc_zero(tmp_ctx, struct resolv_hostent); + if (!rhostent) { + ret = ENOMEM; + goto done; + } + + rhostent->name = talloc_strdup(rhostent, path); + rhostent->addr_list = talloc_array(rhostent, struct resolv_addr *, 1); + + if (!rhostent->name || + !rhostent->addr_list) { + ret = ENOMEM; + goto done; + } + + rhostent->addr_list[0] = NULL; + rhostent->family = AF_UNIX; + rhostent->aliases = NULL; + + *_rhostent = talloc_move(mem_ctx, &rhostent); + ret = EOK; +done: + talloc_free(tmp_ctx); + return ret; +} + +static errno_t +resolv_gethostbyname_address(TALLOC_CTX *mem_ctx, const char *address, + struct resolv_hostent **_rhostent) +{ + struct resolv_hostent *rhostent; + TALLOC_CTX *tmp_ctx; + errno_t ret; + int family; + + tmp_ctx = talloc_new(NULL); + if (!tmp_ctx) return ENOMEM; + + rhostent = talloc_zero(tmp_ctx, struct resolv_hostent); + if (!rhostent) { + ret = ENOMEM; + goto done; + } + + rhostent->name = talloc_strdup(rhostent, address); + rhostent->addr_list = talloc_array(rhostent, struct resolv_addr *, 2); + + if (!rhostent->name || + !rhostent->addr_list) { + ret = ENOMEM; + goto done; + } + + rhostent->addr_list[0] = talloc_zero(rhostent->addr_list, + struct resolv_addr); + if (!rhostent->addr_list[0]) { + ret = ENOMEM; + goto done; + } + rhostent->addr_list[0]->ipaddr = talloc_array(rhostent->addr_list[0], + uint8_t, + sizeof(struct in6_addr)); + if (!rhostent->addr_list[0]->ipaddr) { + ret = ENOMEM; + goto done; + } + + family = AF_INET; + ret = inet_pton(family, address, + rhostent->addr_list[0]->ipaddr); + if (ret != 1) { + family = AF_INET6; + ret = inet_pton(family, address, + rhostent->addr_list[0]->ipaddr); + if (ret != 1) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Could not parse address as neither v4 nor v6\n"); + ret = EINVAL; + goto done; + } + } + + rhostent->addr_list[0]->ttl = RESOLV_DEFAULT_TTL; + rhostent->addr_list[1] = NULL; + rhostent->family = family; + rhostent->aliases = NULL; + + *_rhostent = talloc_move(mem_ctx, &rhostent); + ret = EOK; +done: + talloc_free(tmp_ctx); + return ret; +} + +static inline int +resolv_gethostbyname_family_init(enum restrict_family family_order) +{ + switch(family_order) { + case IPV4_ONLY: + case IPV4_FIRST: + return AF_INET; + case IPV6_ONLY: + case IPV6_FIRST: + return AF_INET6; + } + + DEBUG(SSSDBG_CRIT_FAILURE, + "Unknown address family order %d\n", family_order); + return -1; +} + +static int +resolv_gethostbyname_next(struct gethostbyname_state *state) +{ + if (state->family_order == IPV4_FIRST && + state->family == AF_INET) { + state->family = AF_INET6; + return EOK; + } else if (state->family_order == IPV6_FIRST && + state->family == AF_INET6) { + state->family = AF_INET; + return EOK; + } else { + /* No more address families for this DB, check if + * there is another DB to try */ + DEBUG(SSSDBG_FUNC_DATA, "No more address families to retry\n"); + state->dbi++; + if (state->db[state->dbi] != DB_SENTINEL) { + state->family = resolv_gethostbyname_family_init( + state->family_order); + return EOK; + } + } + + DEBUG(SSSDBG_CONF_SETTINGS, "No more hosts databases to retry\n"); + return ENOENT; +} + +static void +resolv_gethostbyname_done(struct tevent_req *subreq); + +static errno_t +resolv_gethostbyname_step(struct tevent_req *req) +{ + struct gethostbyname_state *state = tevent_req_data(req, + struct gethostbyname_state); + struct tevent_req *subreq; + + switch(state->db[state->dbi]) { + case DB_FILES: + DEBUG(SSSDBG_TRACE_INTERNAL, "Querying files\n"); + subreq = resolv_gethostbyname_files_send(state, state->ev, + state->resolv_ctx, + state->name, + state->family); + break; + case DB_DNS: + DEBUG(SSSDBG_TRACE_INTERNAL, "Querying DNS\n"); + subreq = resolv_gethostbyname_dns_send(state, state->ev, + state->resolv_ctx, + state->name, + state->family); + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, "Invalid hosts database\n"); + return EINVAL; + } + + if (subreq == NULL) { + return ENOMEM; + } + + tevent_req_set_callback(subreq, resolv_gethostbyname_done, req); + return EOK; +} + +static void +resolv_gethostbyname_done(struct tevent_req *subreq) +{ + struct tevent_req *req = tevent_req_callback_data(subreq, + struct tevent_req); + struct gethostbyname_state *state = tevent_req_data(req, + struct gethostbyname_state); + errno_t ret; + + switch(state->db[state->dbi]) { + case DB_FILES: + ret = resolv_gethostbyname_files_recv(subreq, state, + &state->status, + &state->rhostent); + /* files is synchronous, there can be no timeouts */ + state->timeouts = 0; + break; + case DB_DNS: + ret = resolv_gethostbyname_dns_recv(subreq, state, + &state->status, &state->timeouts, + &state->rhostent); + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, "Invalid hosts database\n"); + tevent_req_error(req, EINVAL); + return; + } + + talloc_zfree(subreq); + + if (ret == ENOENT) { + ret = resolv_gethostbyname_next(state); + if (ret == EOK) { + ret = resolv_gethostbyname_step(req); + if (ret != EOK) { + tevent_req_error(req, ret); + } + return; + } + + /* No more databases and/or address families */ + tevent_req_error(req, ENOENT); + return; + } else if (ret == ETIMEDOUT) { + /* In case we killed the request before c-ares answered */ + state->status = ARES_ETIMEOUT; + } + + if (ret != EOK) { + DEBUG(SSSDBG_OP_FAILURE, "querying hosts database failed [%d]: %s\n", + ret, strerror(ret)); + tevent_req_error(req, ret); + return; + } + + tevent_req_done(req); +} + +int +resolv_gethostbyname_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx, + int *status, int *timeouts, + struct resolv_hostent **rhostent) +{ + struct gethostbyname_state *state = tevent_req_data(req, struct gethostbyname_state); + + /* Fill in even in case of error as status contains the + * c-ares return code */ + if (status) { + *status = state->status; + } + if (timeouts) { + *timeouts = state->timeouts; + } + if (rhostent) { + *rhostent = talloc_steal(mem_ctx, state->rhostent); + } + + TEVENT_REQ_RETURN_ON_ERROR(req); + + return EOK; +} + +char * +resolv_get_string_address_index(TALLOC_CTX *mem_ctx, + struct resolv_hostent *hostent, + unsigned int addrindex) +{ + char *address; + + if (!hostent) return NULL; + + address = talloc_zero_size(mem_ctx, 128); + if (address == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "talloc_zero failed.\n"); + return NULL; + } + + errno = 0; + if (inet_ntop(hostent->family, hostent->addr_list[addrindex]->ipaddr, + address, 128) == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "inet_ntop failed [%d][%s].\n", errno, strerror(errno)); + talloc_free(address); + return NULL; + } + + return address; +} + +char * +resolv_get_string_ptr_address(TALLOC_CTX *mem_ctx, + int family, uint8_t *address) +{ + char *straddr; + + if (family == AF_INET6) { + int i; + char hexbyte[3]; + + straddr = talloc_strdup(mem_ctx, "\0"); + if (!straddr) { + return NULL; + } + + for (i = 15; i >= 0; i--) { + snprintf(hexbyte, 3, "%02x", address[i]); + straddr = talloc_asprintf_append(straddr, "%c.%c.", + hexbyte[1], hexbyte[0]); + } + straddr = talloc_asprintf_append(straddr, "ip6.arpa."); + } else if (family == AF_INET) { + straddr = talloc_asprintf(mem_ctx, + "%u.%u.%u.%u.in-addr.arpa.", + (address[3]), + (address[2]), + (address[1]), + (address[0])); + } else { + DEBUG(SSSDBG_CRIT_FAILURE, "Unknown address family\n"); + return NULL; + } + + return straddr; +} + +struct sockaddr * +resolv_get_sockaddr_address_index(TALLOC_CTX *mem_ctx, + struct resolv_hostent *hostent, + int port, int addrindex, + socklen_t *sockaddr_len) +{ + struct sockaddr *sockaddr; + int len; + + if (!hostent) return NULL; + + switch(hostent->family) { + case AF_INET: + len = sizeof(struct sockaddr_in); + break; + case AF_INET6: + len = sizeof(struct sockaddr_in6); + break; + case AF_UNIX: + len = sizeof(struct sockaddr_un); + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, + "Unknown address family %d\n", hostent->family); + return NULL; + } + + sockaddr = (struct sockaddr *)talloc_zero(mem_ctx, struct sockaddr_storage); + if (sockaddr == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "talloc_zero failed.\n"); + return NULL; + } + + switch(hostent->family) { + case AF_INET: + sockaddr->sa_family = AF_INET; + memcpy(&((struct sockaddr_in *) sockaddr)->sin_addr, + hostent->addr_list[addrindex]->ipaddr, + sizeof(struct in_addr)); + ((struct sockaddr_in *) sockaddr)->sin_port = (in_port_t) htons(port); + + break; + case AF_INET6: + sockaddr->sa_family = AF_INET6; + memcpy(&((struct sockaddr_in6 *) sockaddr)->sin6_addr, + hostent->addr_list[addrindex]->ipaddr, + sizeof(struct in6_addr)); + ((struct sockaddr_in6 *) sockaddr)->sin6_port = (in_port_t) htons(port); + break; + case AF_UNIX: + sockaddr->sa_family = AF_UNIX; + strncpy(((struct sockaddr_un *) sockaddr)->sun_path, hostent->name, + sizeof(((struct sockaddr_un *) sockaddr)->sun_path) - 1); + if (strlen(hostent->name) >= + sizeof(((struct sockaddr_un *) sockaddr)->sun_path)) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Path '%s' too long\n", hostent->name); + return NULL; + } + break; + default: + DEBUG(SSSDBG_CRIT_FAILURE, + "Unknown address family %d\n", hostent->family); + return NULL; + } + + if (sockaddr_len != NULL) { + *sockaddr_len = len; + } + + return sockaddr; +} + +/* + * A simple helper function that will take an array of struct ares_srv_reply that + * was allocated by malloc() in c-ares and copies it using talloc. The old one + * is freed and the talloc one is put into 'reply_list' instead. + */ +static int +rewrite_talloc_srv_reply(TALLOC_CTX *mem_ctx, struct ares_srv_reply **reply_list) +{ + struct ares_srv_reply *ptr = NULL; + struct ares_srv_reply *new_list = NULL; + struct ares_srv_reply *old_list = *reply_list; + + /* Nothing to do, but not an error */ + if (!old_list) { + return EOK; + } + + /* Copy the linked list */ + while (old_list) { + /* Special case for the first node */ + if (!new_list) { + new_list = talloc_zero(mem_ctx, struct ares_srv_reply); + if (new_list == NULL) { + ares_free_data(*reply_list); + return ENOMEM; + } + ptr = new_list; + } else { + ptr->next = talloc_zero(new_list, struct ares_srv_reply); + if (ptr->next == NULL) { + ares_free_data(*reply_list); + talloc_free(new_list); + return ENOMEM; + } + ptr = ptr->next; + } + + ptr->weight = old_list->weight; + ptr->priority = old_list->priority; + ptr->port = old_list->port; + ptr->host = talloc_strdup(ptr, old_list->host); + if (ptr->host == NULL) { + ares_free_data(*reply_list); + talloc_free(new_list); + return ENOMEM; + } + + old_list = old_list->next; + } + + /* Free the old one (uses malloc). */ + ares_free_data(*reply_list); + + /* And now put our own new_list in place. */ + *reply_list = new_list; + + return EOK; +} + +/******************************************************************* + * Get SRV record * + *******************************************************************/ + +struct getsrv_state { + struct tevent_context *ev; + struct resolv_ctx *resolv_ctx; + /* the SRV query - for example _ldap._tcp.example.com */ + const char *query; + + /* parsed data returned by ares */ + struct ares_srv_reply *reply_list; + uint32_t ttl; + int status; + int timeouts; + int retrying; +}; + +static void +ares_getsrv_wakeup(struct tevent_req *subreq); +static void +resolv_getsrv_query(struct tevent_req *req, + struct getsrv_state *state); + +struct tevent_req * +resolv_getsrv_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + struct resolv_ctx *ctx, const char *query) +{ + struct tevent_req *req, *subreq; + struct getsrv_state *state; + struct timeval tv = { 0, 0 }; + + DEBUG(SSSDBG_CONF_SETTINGS, + "Trying to resolve SRV record of '%s'\n", query); + + if (ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + return NULL; + } + + req = tevent_req_create(mem_ctx, &state, struct getsrv_state); + if (req == NULL) + return NULL; + + state->resolv_ctx = ctx; + state->query = query; + state->reply_list = NULL; + state->ttl = 0; + state->status = 0; + state->timeouts = 0; + state->retrying = 0; + state->ev = ev; + + subreq = tevent_wakeup_send(req, ev, tv); + if (subreq == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Failed to add critical timer to run next operation!\n"); + talloc_zfree(req); + return NULL; + } + tevent_req_set_callback(subreq, ares_getsrv_wakeup, req); + + return req; +} + +/* + * Implemented based on http://tools.ietf.org/html/rfc2181#section-5 + * + * Especially: + * 5.2. TTLs of RRs in an RRSet + * Consequently the use of differing TTLs in an RRSet is hereby + * deprecated, the TTLs of all RRs in an RRSet must be the same. + * ... + * Should an authoritative source send such a malformed RRSet, the + * client should treat the RRs for all purposes as if all TTLs in the + * RRSet had been set to the value of the lowest TTL in the RRSet. + * + * On success, returns true and sets the TTL in the _ttl parameter. On + * failure, returns false and _ttl is undefined. + */ +static bool +resolv_get_ttl(const unsigned char *abuf, const int alen, uint32_t *_ttl) +{ + const unsigned char *aptr; + int ret; + char *name = NULL; + long len; + uint32_t ttl = 0; + uint32_t rr_ttl; + unsigned int rr_len; + unsigned int ancount; + unsigned int i; + + /* Read the number of RRs and then skip past the header */ + if (alen < NS_HFIXEDSZ) { + return false; + } + + ancount = DNS_HEADER_ANCOUNT(abuf); + if (ancount == 0) { + return false; + } + + aptr = abuf + NS_HFIXEDSZ; + + /* We only care about len from the question data, + * so that we can move past hostname */ + ret = ares_expand_name(aptr, abuf, alen, &name, &len); + ares_free_string(name); + if (ret != ARES_SUCCESS) { + return false; + } + + /* Skip past the question */ + aptr += len + NS_QFIXEDSZ; + if (aptr > abuf + alen) { + return false; + } + + /* Examine each RR in turn and read the lowest TTL */ + for (i = 0; i < ancount; i++) { + /* Decode the RR up to the data field. */ + ret = ares_expand_name(aptr, abuf, alen, &name, &len); + ares_free_string(name); + if (ret != ARES_SUCCESS) { + return false; + } + + aptr += len; + if (aptr + NS_RRFIXEDSZ > abuf + alen) { + return false; + } + + rr_len = DNS_RR_LEN(aptr); + rr_ttl = DNS_RR_TTL(aptr); + if (aptr + rr_len > abuf + alen) { + return false; + } + aptr += NS_RRFIXEDSZ + rr_len; + + if (ttl > 0) { + ttl = MIN(ttl, rr_ttl); + } else { + ttl = rr_ttl; /* special-case for first TTL */ + } + } + + *_ttl = ttl; + return true; +} + +static void +resolv_getsrv_done(void *arg, int status, int timeouts, unsigned char *abuf, int alen) +{ + struct resolv_request *rreq = talloc_get_type(arg, struct resolv_request); + struct tevent_req *req; + struct getsrv_state *state; + int ret; + bool ok; + struct ares_srv_reply *reply_list; + + if (rreq->rwatch == NULL) { + /* The tevent request was cancelled while the ares call was still in + * progress so nobody cares about the result now. Quit. */ + unschedule_timeout_watcher(rreq->ctx, rreq); + return; + } + + req = rreq->rwatch->req; + unschedule_timeout_watcher(rreq->ctx, rreq); + state = tevent_req_data(req, struct getsrv_state); + + if (state->retrying == 0 && status == ARES_EDESTRUCTION + && state->resolv_ctx->channel != NULL) { + state->retrying = 1; + resolv_getsrv_query(req, state); + return; + } + + state->status = status; + state->timeouts = timeouts; + + if (status != ARES_SUCCESS) { + ret = return_code(status); + goto fail; + } + + ret = ares_parse_srv_reply(abuf, alen, &reply_list); + if (ret != ARES_SUCCESS) { + DEBUG(SSSDBG_OP_FAILURE, + "SRV record parsing failed: %d: %s\n", ret, ares_strerror(ret)); + ret = return_code(ret); + goto fail; + } + ret = rewrite_talloc_srv_reply(req, &reply_list); + if (ret != EOK) { + goto fail; + } + state->reply_list = reply_list; + ok = resolv_get_ttl(abuf, alen, &state->ttl); + if (ok == false) { + DEBUG(SSSDBG_MINOR_FAILURE, "Could not read TTL, using the default..\n"); + state->ttl = RESOLV_DEFAULT_SRV_TTL; + } + DEBUG(SSSDBG_TRACE_LIBS, "Using TTL [%"PRIu32"]\n", state->ttl); + + tevent_req_done(req); + return; + +fail: + state->reply_list = NULL; + tevent_req_error(req, ret); +} + +int +resolv_getsrv_recv(TALLOC_CTX *mem_ctx, struct tevent_req *req, int *status, + int *timeouts, struct ares_srv_reply **reply_list, + uint32_t *ttl) +{ + struct getsrv_state *state = tevent_req_data(req, struct getsrv_state); + + if (status) + *status = state->status; + if (timeouts) + *timeouts = state->timeouts; + if (reply_list) + *reply_list = talloc_steal(mem_ctx, state->reply_list); + if (ttl) { + *ttl = state->ttl; + } + + TEVENT_REQ_RETURN_ON_ERROR(req); + + return EOK; +} + +static void +ares_getsrv_wakeup(struct tevent_req *subreq) +{ + struct tevent_req *req = tevent_req_callback_data(subreq, + struct tevent_req); + struct getsrv_state *state = tevent_req_data(req, + struct getsrv_state); + + if (!tevent_wakeup_recv(subreq)) { + return; + } + talloc_zfree(subreq); + + if (state->resolv_ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + tevent_req_error(req, EIO); + return; + } + + return resolv_getsrv_query(req, state); +} + +static void +resolv_getsrv_query(struct tevent_req *req, + struct getsrv_state *state) +{ + struct resolv_request *rreq; + + rreq = schedule_timeout_watcher(state->ev, state->resolv_ctx, req); + if (!rreq) { + tevent_req_error(req, ENOMEM); + return; + } + + ares_query(state->resolv_ctx->channel, state->query, + ns_c_in, ns_t_srv, resolv_getsrv_done, rreq); +} + +/* TXT parsing is not used anywhere in the code yet, so we disable it + * for now + */ +#ifdef BUILD_TXT + +/* + * A simple helper function that will take an array of struct txt_reply that + * was allocated by malloc() in c-ares and copies it using talloc. The old one + * is freed and the talloc one is put into 'reply_list' instead. + */ +static int +rewrite_talloc_txt_reply(TALLOC_CTX *mem_ctx, struct ares_txt_reply **reply_list) +{ + struct ares_txt_reply *ptr = NULL; + struct ares_txt_reply *new_list = NULL; + struct ares_txt_reply *old_list = *reply_list; + + /* Nothing to do, but not an error */ + if (!old_list) { + return EOK; + } + + /* Copy the linked list */ + while (old_list) { + + /* Special case for the first node */ + if (!new_list) { + new_list = talloc_zero(mem_ctx, struct ares_txt_reply); + if (new_list == NULL) { + ares_free_data(*reply_list); + talloc_free(new_list); + return ENOMEM; + } + ptr = new_list; + } else { + ptr->next = talloc_zero(new_list, struct ares_txt_reply); + if (ptr->next == NULL) { + ares_free_data(*reply_list); + talloc_free(new_list); + return ENOMEM; + } + ptr = ptr->next; + } + + ptr->length = old_list->length; + ptr->txt = talloc_memdup(ptr, old_list->txt, + old_list->length); + if (ptr->txt == NULL) { + ares_free_data(*reply_list); + talloc_free(new_list); + return ENOMEM; + } + + old_list = old_list->next; + } + + ares_free_data(*reply_list); + + /* And now put our own new_list in place. */ + *reply_list = new_list; + + return EOK; +} + +/******************************************************************* + * Get TXT record * + *******************************************************************/ + +struct gettxt_state { + struct tevent_context *ev; + struct resolv_ctx *resolv_ctx; + /* the TXT query */ + const char *query; + + /* parsed data returned by ares */ + struct ares_txt_reply *reply_list; + int status; + int timeouts; + int retrying; +}; + +static void +ares_gettxt_wakeup(struct tevent_req *subreq); +static void +resolv_gettxt_query(struct tevent_req *req, + struct gettxt_state *state); + +struct tevent_req * +resolv_gettxt_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev, + struct resolv_ctx *ctx, const char *query) +{ + struct tevent_req *req, *subreq; + struct gettxt_state *state; + struct timeval tv = { 0, 0 }; + + DEBUG(SSSDBG_CONF_SETTINGS, + "Trying to resolve TXT record of '%s'\n", query); + + if (ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + return NULL; + } + + req = tevent_req_create(mem_ctx, &state, struct gettxt_state); + if (req == NULL) + return NULL; + + state->resolv_ctx = ctx; + state->query = query; + state->reply_list = NULL; + state->status = 0; + state->timeouts = 0; + state->retrying = 0; + state->ev = ev; + + subreq = tevent_wakeup_send(req, ev, tv); + if (subreq == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Failed to add critical timer to run next operation!\n"); + talloc_zfree(req); + return NULL; + } + tevent_req_set_callback(subreq, ares_gettxt_wakeup, req); + + return req; +} + +static void +resolv_gettxt_done(void *arg, int status, int timeouts, unsigned char *abuf, int alen) +{ + struct resolv_request *rreq = talloc_get_type(arg, struct resolv_request); + struct tevent_req *req; + struct gettxt_state *state; + int ret; + struct ares_txt_reply *reply_list; + + if (rreq->rwatch == NULL) { + /* The tevent request was cancelled while the ares call was still in + * progress so nobody cares about the result now. Quit. */ + unschedule_timeout_watcher(rreq->ctx, rreq); + return; + } + + req = rreq->rwatch->req; + unschedule_timeout_watcher(rreq->ctx, rreq); + state = tevent_req_data(req, struct gettxt_state); + + if (state->retrying == 0 && status == ARES_EDESTRUCTION + && state->resolv_ctx->channel != NULL) { + state->retrying = 1; + ares_query(state->resolv_ctx->channel, state->query, + ns_c_in, ns_t_txt, resolv_gettxt_done, req); + return; + } + + state->status = status; + state->timeouts = timeouts; + + if (status != ARES_SUCCESS) { + ret = return_code(status); + goto fail; + } + + ret = ares_parse_txt_reply(abuf, alen, &reply_list); + if (status != ARES_SUCCESS) { + DEBUG(SSSDBG_OP_FAILURE, + "TXT record parsing failed: %d: %s\n", ret, ares_strerror(ret)); + ret = return_code(ret); + goto fail; + } + ret = rewrite_talloc_txt_reply(req, &reply_list); + if (ret != EOK) { + goto fail; + } + state->reply_list = reply_list; + + tevent_req_done(req); + return; + +fail: + state->reply_list = NULL; + tevent_req_error(req, ret); +} + +int +resolv_gettxt_recv(TALLOC_CTX *mem_ctx, struct tevent_req *req, int *status, + int *timeouts, struct ares_txt_reply **reply_list) +{ + struct gettxt_state *state = tevent_req_data(req, struct gettxt_state); + + if (status) + *status = state->status; + if (timeouts) + *timeouts = state->timeouts; + if (reply_list) + *reply_list = talloc_steal(mem_ctx, state->reply_list); + + TEVENT_REQ_RETURN_ON_ERROR(req); + + return EOK; +} + +static void +ares_gettxt_wakeup(struct tevent_req *subreq) +{ + struct tevent_req *req = tevent_req_callback_data(subreq, + struct tevent_req); + struct gettxt_state *state = tevent_req_data(req, + struct gettxt_state); + + if (!tevent_wakeup_recv(subreq)) { + return; + } + talloc_zfree(subreq); + + if (state->resolv_ctx->channel == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Invalid ares channel - this is likely a bug\n"); + tevent_req_error(req, EIO); + return; + } + + return resolv_gettxt_query(req, state); +} + +static void +resolv_gettxt_query(struct tevent_req *req, + struct gettxt_state *state) +{ + struct resolv_request *rreq; + + rreq = schedule_timeout_watcher(state->ev, state->resolv_ctx, req); + if (!rreq) { + tevent_req_error(req, ENOMEM); + return; + } + + ares_query(state->resolv_ctx->channel, state->query, + ns_c_in, ns_t_txt, resolv_gettxt_done, rreq); +} + +#endif + +static struct ares_srv_reply *split_reply_list(struct ares_srv_reply *list) +{ + struct ares_srv_reply *single_step, *double_step, *prev; + + if (!list) { + return NULL; + } + + prev = list; + single_step = list->next; + double_step = single_step->next; + + while (double_step && double_step->next) { + prev = single_step; + single_step = single_step->next; + double_step = double_step->next->next; + } + + prev->next = NULL; + return single_step; +} + +static struct ares_srv_reply *merge_reply_list(struct ares_srv_reply *left, + struct ares_srv_reply *right) +{ + struct ares_srv_reply *l, *r; + struct ares_srv_reply *res, *res_start; + + if (!left) + return right; + if (!right) + return left; + + if (left->priority < right->priority) { + res_start = left; + l = left->next; + r = right; + } else { + res_start = right; + l = left; + r = right->next; + } + + res = res_start; + + while(l && r) { + if (l->priority < r->priority) { + res->next = l; + res = l; + l = l->next; + } else { + res->next = r; + res = r; + r = r->next; + } + } + + res->next = l ? l : r; + + return res_start; +} + +/** + * sort linked list of struct ares_srv_reply by priority using merge sort. + * + * Merge sort is ideal for sorting linked lists as there is no problem + * with absence of random access into the list. The complexity is O(n log n) + * + * For reference, see Robert Sedgewick's "Algorithms in C", Addison-Wesley, + * ISBN 0-201-51425 + */ +static struct ares_srv_reply *reply_priority_sort(struct ares_srv_reply *list) +{ + struct ares_srv_reply *half; + + if (!list || !list->next) + return list; + + half = split_reply_list(list); + list = merge_reply_list(reply_priority_sort(list), + reply_priority_sort(half)); + + return list; +} + +static int reply_weight_rearrange(int len, + struct ares_srv_reply **start, + struct ares_srv_reply **end) +{ + int i; + int total, selected; + int *totals; + struct ares_srv_reply *r, *prev, *tmp; + struct ares_srv_reply *new_start = NULL; + struct ares_srv_reply *new_end = NULL; + int ret; + + if (len <= 1) { + return EOK; + } + + totals = talloc_array(NULL, int, len); + if (!totals) { + return ENOMEM; + } + + /* promote all servers with weight==0 to the top */ + r = *(start); + prev = NULL; + while (r != NULL) { + if (r->weight == 0 && r != *start) { + /* remove from the old list */ + prev->next = r->next; + + /* add to the head of the new list */ + tmp = r; + r = r->next; + + tmp->next = *start; + *start = tmp; + } else { + prev = r; + r = r->next; + } + } + *end = prev ? prev : *start; + + while (*start != NULL) { + /* Compute the sum of the weights of those RRs, and with each RR + * associate the running sum in the selected order. + */ + total = 0; + memset(totals, -1, sizeof(int) * len); + for (i = 0, r = *start; r != NULL; r=r->next, ++i) { + totals[i] = r->weight + total; + total = totals[i]; + } + + /* choose a uniform random number between 0 and the sum computed + * (inclusive), and select the RR whose running sum value is the + * first in the selected order which is greater than or equal to + * the random number selected. + */ + selected = (int)((total + 1) * (sss_rand()/(RAND_MAX + 1.0))); + for (i = 0, r = *start, prev = NULL; r != NULL; r=r->next, ++i) { + if (totals[i] >= selected) + break; + + prev = r; + } + + if (r == NULL || totals[i] == -1) { + DEBUG(SSSDBG_CRIT_FAILURE, "Bug: did not select any server!\n"); + ret = EIO; + goto done; + } + + /* remove r from the old list */ + if (prev) { + prev->next = r->next; + } else { + *start = r->next; + } + + /* add r to the end of the new list */ + if (!new_start) { + new_start = r; + new_end = r; + } else { + new_end->next = r; + new_end = r; + } + } + + if (new_end == NULL) { + ret = EINVAL; + DEBUG(SSSDBG_CRIT_FAILURE, + "Bug: no new server has been selected!\n"); + goto done; + } + new_end->next = NULL; + + /* return the rearranged list */ + *start = new_start; + *end = new_end; + ret = EOK; + +done: + talloc_free(totals); + return ret; +} + +int +resolv_sort_srv_reply(struct ares_srv_reply **reply) +{ + int ret; + struct ares_srv_reply *pri_start, *pri_end, *next, *prev_end; + int len; + + /* RFC 2782 says: If there is precisely one SRV RR, and its Target is "." + * (the root domain), abort. + */ + if (*reply && !(*reply)->next && strcmp((*reply)->host, ".") == 0) { + DEBUG(SSSDBG_CRIT_FAILURE, + "DNS returned only the root domain, aborting\n"); + return EIO; + } + + /* sort the list by priority */ + *reply = reply_priority_sort(*reply); + + pri_start = *reply; + prev_end = NULL; + + while (pri_start) { + pri_end = pri_start; + + /* Find nodes with the same priority */ + len = 1; + while (pri_end->next && pri_end->priority == pri_end->next->priority) { + pri_end = pri_end->next; + len++; + } + + /* rearrange each priority level according to the weight field */ + next = pri_end->next; + pri_end->next = NULL; + ret = reply_weight_rearrange(len, &pri_start, &pri_end); + if (ret) { + DEBUG(SSSDBG_CRIT_FAILURE, + "Error rearranging priority level [%d]: %s\n", + ret, strerror(ret)); + return ret; + } + + /* Hook the level back into the list */ + if (prev_end) { + prev_end->next = pri_start; + } else { + *reply = pri_start; + } + pri_end->next = next; + + /* Move on to the next level */ + prev_end = pri_end; + pri_start = next; + } + + return EOK; +} + +struct resolv_hostport_list_state { + struct tevent_context *ev; + struct resolv_ctx *ctx; + struct resolv_hostport *hostport_list; + size_t list_size; + size_t limit; + enum restrict_family family_order; + enum host_database *db; + + size_t hpindex; + + struct resolv_hostport_addr **rhp_addrs; + size_t addrindex; +}; + +static errno_t resolv_hostport_list_step(struct tevent_req *req); +static void resolv_hostport_list_resolv_hostname_done(struct tevent_req *subreq); + +struct tevent_req *resolv_hostport_list_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + struct resolv_hostport *hostport_list, + size_t list_size, + size_t limit, + enum restrict_family family_order, + enum host_database *db) +{ + struct resolv_hostport_list_state *state; + struct tevent_req *req; + errno_t ret; + + req = tevent_req_create(mem_ctx, &state, + struct resolv_hostport_list_state); + if (req == NULL) { + return NULL; + } + state->ev = ev; + state->ctx = ctx; + state->hostport_list = hostport_list; + state->family_order = family_order; + state->db = db; + state->list_size = list_size; + state->limit = limit; + + state->rhp_addrs = talloc_array(state, + struct resolv_hostport_addr *, + state->list_size); + if (state->rhp_addrs == NULL) { + ret = ENOMEM; + goto immediately; + } + + ret = resolv_hostport_list_step(req); + if (ret != EAGAIN) { + goto immediately; + } + + return req; + +immediately: + if (ret != EOK) { + tevent_req_error(req, ret); + } else { + tevent_req_done(req); + } + tevent_req_post(req, ev); + return req; +} + +static errno_t resolv_hostport_list_step(struct tevent_req *req) +{ + struct tevent_req *subreq = NULL; + struct resolv_hostport_list_state *state = tevent_req_data(req, + struct resolv_hostport_list_state); + + if (state->hpindex >= state->list_size) { + DEBUG(SSSDBG_TRACE_INTERNAL, "Done\n"); + return EOK; + } + + subreq = resolv_gethostbyname_send(state, + state->ev, + state->ctx, + state->hostport_list[state->hpindex].host, + state->family_order, + state->db); + if (subreq == NULL) { + return ENOMEM; + } + tevent_req_set_callback(subreq, + resolv_hostport_list_resolv_hostname_done, req); + return EAGAIN; +} + +static struct resolv_hostport_addr* +resolv_hostport_addr_new(TALLOC_CTX *mem_ctx, + const char *host, + int port, + struct resolv_hostent *reply) +{ + struct resolv_hostport_addr *rhp_addr; + + rhp_addr = talloc_zero(mem_ctx, struct resolv_hostport_addr); + if (rhp_addr == NULL) { + return NULL; + } + + rhp_addr->origin.host = talloc_strdup(rhp_addr, host); + if (rhp_addr->origin.host == NULL) { + return NULL; + } + + rhp_addr->origin.port = port; + rhp_addr->reply = talloc_steal(rhp_addr, reply); + return rhp_addr; +} + +static void resolv_hostport_list_resolv_hostname_done(struct tevent_req *subreq) +{ + errno_t ret; + struct tevent_req *req = + tevent_req_callback_data(subreq, struct tevent_req); + struct resolv_hostport_list_state *state = tevent_req_data(req, + struct resolv_hostport_list_state); + struct resolv_hostent *rhostent; + int resolv_status; + + ret = resolv_gethostbyname_recv(subreq, state, &resolv_status, NULL, + &rhostent); + talloc_zfree(subreq); + + if (ret != EOK) { + /* Don't abort the request, just go to the next one */ + DEBUG(SSSDBG_OP_FAILURE, + "Could not resolve address for this machine, error [%d]: %s, " + "resolver returned: [%d]: %s\n", ret, sss_strerror(ret), + resolv_status, resolv_strerror(resolv_status)); + } else { + state->rhp_addrs[state->addrindex] = \ + resolv_hostport_addr_new(state->rhp_addrs, + state->hostport_list[state->hpindex].host, + state->hostport_list[state->hpindex].port, + rhostent); + state->addrindex++; + + if (state->limit > 0 && state->addrindex >= state->limit) { + DEBUG(SSSDBG_TRACE_INTERNAL, + "Reached the limit or addresses to resolve\n"); + tevent_req_done(req); + return; + } + } + + state->hpindex++; + + ret = resolv_hostport_list_step(req); + if (ret == EOK) { + tevent_req_done(req); + return; + } else if (ret != EAGAIN) { + tevent_req_error(req, ret); + return; + } + /* Next iteration .. */ +} + +int resolv_hostport_list_recv(struct tevent_req *req, + TALLOC_CTX *mem_ctx, + size_t *_rhp_len, + struct resolv_hostport_addr ***_rhp_addrs) +{ + struct resolv_hostport_list_state *state = tevent_req_data(req, + struct resolv_hostport_list_state); + + TEVENT_REQ_RETURN_ON_ERROR(req); + + if (_rhp_len) { + *_rhp_len = state->addrindex; + } + + if (_rhp_addrs) { + *_rhp_addrs = talloc_steal(mem_ctx, state->rhp_addrs); + } + + return EOK; +} diff --git a/src/resolv/async_resolv.h b/src/resolv/async_resolv.h new file mode 100644 index 0000000..a1f9285 --- /dev/null +++ b/src/resolv/async_resolv.h @@ -0,0 +1,230 @@ +/* + SSSD + + Async resolver header + + Authors: + Martin Nagy <mnagy@redhat.com> + Jakub Hrozek <jhrozek@redhat.com> + + Copyright (C) Red Hat, Inc 2009 + + 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/>. +*/ + +#ifndef __ASYNC_RESOLV_H__ +#define __ASYNC_RESOLV_H__ + +#include <netdb.h> +#include <ares.h> + +#include "config.h" +#include "confdb/confdb.h" + +#ifndef RESOLV_DEFAULT_TTL +#define RESOLV_DEFAULT_TTL 7200 +#endif /* RESOLV_DEFAULT_TTL */ + +#ifndef RESOLV_DEFAULT_SRV_TTL +#define RESOLV_DEFAULT_SRV_TTL 14400 +#endif /* RESOLV_DEFAULT_SRV_TTL */ + +#include "util/util.h" + +/* + * An opaque structure which holds context for a module using the async + * resolver. Is should be used as a "local-global" variable - in sssd, + * every backend should have its own. + + * Do NOT free the context until there are any pending resolv_ calls + */ +struct resolv_ctx; + +int resolv_init(TALLOC_CTX *mem_ctx, struct tevent_context *ev_ctx, + int timeout, int ares_timeout, bool use_search_list, + struct resolv_ctx **ctxp); + +void resolv_reread_configuration(struct resolv_ctx *ctx); + +const char *resolv_strerror(int ares_code); + +struct resolv_hostent * +resolv_copy_hostent(TALLOC_CTX *mem_ctx, struct hostent *src); + +struct resolv_hostent * +resolv_copy_hostent_ares(TALLOC_CTX *mem_ctx, struct hostent *src, + int family, void *ares_ttl_data, + int num_ares_ttl_data); + +/** Get host by name **/ +enum host_database { + DB_FILES, + DB_DNS, + + DB_SENTINEL +}; + +enum restrict_family { + IPV4_ONLY, + IPV4_FIRST, + IPV6_ONLY, + IPV6_FIRST +}; + +/* If resolv_hostent->family is AF_INET, then ipaddr points to + * struct in_addr, else if family is AF_INET6, ipaddr points to + * struct in6_addr + */ +struct resolv_addr { + uint8_t *ipaddr; + int ttl; +}; + +struct resolv_hostent { + char *name; /* official name of host */ + char **aliases; /* alias list */ + int family; /* host address type */ + + struct resolv_addr **addr_list; /* list of addresses */ +}; + +/* The default database order */ +extern enum host_database default_host_dbs[]; + +struct tevent_req *resolv_gethostbyname_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + const char *name, + enum restrict_family family_order, + enum host_database *db); + +int resolv_gethostbyname_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx, + int *status, int *timeouts, + struct resolv_hostent **rhostent); + +struct resolv_hostport { + const char *host; + int port; +}; + +struct resolv_hostport_addr { + struct resolv_hostport origin; + struct resolv_hostent *reply; +}; + +/* Resolves a list of resolv_hostport tuples into a list of + * resolv_hostport_addr. Any unresolvable addresses are skipped. + * + * Optionally takes a limit argument and stops after the request + * had resolved addresses up to the limit. + */ +struct tevent_req *resolv_hostport_list_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + struct resolv_hostport *hostport_list, + size_t list_size, + size_t limit, + enum restrict_family family_order, + enum host_database *db); + +int resolv_hostport_list_recv(struct tevent_req *req, + TALLOC_CTX *mem_ctx, + size_t *_rhp_len, + struct resolv_hostport_addr ***_rhp_addrs); + +char * +resolv_get_string_address_index(TALLOC_CTX *mem_ctx, + struct resolv_hostent *hostent, + unsigned int addrindex); + +char * +resolv_get_string_ptr_address(TALLOC_CTX *mem_ctx, + int family, uint8_t *address); + +#define resolv_get_string_address(mem_ctx, hostent) \ + resolv_get_string_address_index(mem_ctx, hostent, 0) + +struct sockaddr * +resolv_get_sockaddr_address_index(TALLOC_CTX *mem_ctx, + struct resolv_hostent *hostent, + int port, int addrindex, + socklen_t *sockaddr_len); + +#define resolv_get_sockaddr_address(mem_ctx, rhostent, port, sockaddr_len) \ + resolv_get_sockaddr_address_index(mem_ctx, rhostent, port, 0, sockaddr_len) + +/** Get SRV record **/ +struct tevent_req *resolv_getsrv_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + const char *query); + +int resolv_getsrv_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + int *status, + int *timeouts, + struct ares_srv_reply **reply_list, + uint32_t *ttl); + +/* This is an implementation of section "Usage rules" of RFC 2782 */ +int +resolv_sort_srv_reply(struct ares_srv_reply **reply); + +/** Get TXT record **/ +struct tevent_req *resolv_gettxt_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *ctx, + const char *query); + +int resolv_gettxt_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + int *status, + int *timeouts, + struct ares_txt_reply **reply_list); + +/** Utils **/ + +struct tevent_req * +resolv_get_domain_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *resolv_ctx, + const char *hostname, + enum host_database *host_dbs, + enum restrict_family family_order); + +errno_t resolv_get_domain_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + char **_dns_domain); + +struct tevent_req * +resolv_discover_srv_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *resolv_ctx, + const char *service, + const char *protocol, + const char **discovery_domains); + +errno_t resolv_discover_srv_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + struct ares_srv_reply **_reply_list, + uint32_t *_ttl, + char **_dns_domain); + +bool +resolv_is_address(const char *name); + +bool +resolv_is_unix(const char *name); + +#endif /* __ASYNC_RESOLV_H__ */ diff --git a/src/resolv/async_resolv_utils.c b/src/resolv/async_resolv_utils.c new file mode 100644 index 0000000..f86181b --- /dev/null +++ b/src/resolv/async_resolv_utils.c @@ -0,0 +1,343 @@ +/* + Authors: + Pavel Březina <pbrezina@redhat.com> + + Copyright (C) 2013 Red Hat + + 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/>. +*/ + +#include <string.h> +#include <talloc.h> +#include <tevent.h> +#include <unistd.h> +#include <limits.h> + +#include "util/util.h" +#include "resolv/async_resolv.h" + +struct resolv_get_domain_state { + char *fqdn; + char *hostname; +}; + +static void resolv_get_domain_done(struct tevent_req *subreq); + +struct tevent_req * +resolv_get_domain_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *resolv_ctx, + const char *hostname, + enum host_database *host_dbs, + enum restrict_family family_order) +{ + struct resolv_get_domain_state *state = NULL; + struct tevent_req *req = NULL; + struct tevent_req *subreq = NULL; + char system_hostname[HOST_NAME_MAX + 1]; + errno_t ret; + + req = tevent_req_create(mem_ctx, &state, + struct resolv_get_domain_state); + if (req == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n"); + return NULL; + } + + if (hostname == NULL) { + /* use system hostname */ + ret = gethostname(system_hostname, sizeof(system_hostname)); + if (ret) { + ret = errno; + DEBUG(SSSDBG_CRIT_FAILURE, "gethostname() failed: [%d]: %s\n", + ret, strerror(ret)); + goto immediately; + } + system_hostname[HOST_NAME_MAX] = '\0'; + hostname = system_hostname; + } + + state->fqdn = NULL; + state->hostname = talloc_strdup(state, hostname); + if (state->hostname == NULL) { + ret = ENOMEM; + goto immediately; + } + + DEBUG(SSSDBG_TRACE_LIBS, "Host name is: %s\n", state->hostname); + + subreq = resolv_gethostbyname_send(state, ev, resolv_ctx, state->hostname, + family_order, host_dbs); + if (subreq == NULL) { + talloc_zfree(req); + return NULL; + } + + tevent_req_set_callback(subreq, resolv_get_domain_done, req); + + return req; + +immediately: + tevent_req_error(req, ret); + tevent_req_post(req, ev); + + return req; +} + +static void resolv_get_domain_done(struct tevent_req *subreq) +{ + struct resolv_get_domain_state *state = NULL; + struct tevent_req *req = NULL; + struct resolv_hostent *rhostent; + int resolv_status; + errno_t ret; + + req = tevent_req_callback_data(subreq, struct tevent_req); + state = tevent_req_data(req, struct resolv_get_domain_state); + + ret = resolv_gethostbyname_recv(subreq, req, &resolv_status, + NULL, &rhostent); + talloc_zfree(subreq); + if (ret != EOK) { + DEBUG(SSSDBG_OP_FAILURE, + "Could not get fully qualified name for host name %s " + "error [%d]: %s, resolver returned: [%d]: %s\n", + state->hostname, ret, strerror(ret), resolv_status, + resolv_strerror(resolv_status)); + state->fqdn = state->hostname; + } else { + DEBUG(SSSDBG_TRACE_LIBS, "The FQDN is: %s\n", rhostent->name); + state->fqdn = talloc_steal(state, rhostent->name); + talloc_zfree(rhostent); + } + + tevent_req_done(req); +} + +errno_t resolv_get_domain_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + char **_dns_domain) +{ + struct resolv_get_domain_state *state = NULL; + char *dns_domain = NULL; + char *domptr = NULL; + + state = tevent_req_data(req, struct resolv_get_domain_state); + + TEVENT_REQ_RETURN_ON_ERROR(req); + + domptr = strchr(state->fqdn, '.'); + if (domptr == NULL || (*(domptr+1) == '\0')) { + /* If the FQDN did not contain a dot or the dot was the last character + * (broken DNS server perhaps) */ + dns_domain = state->fqdn; + } else { + dns_domain = domptr + 1; + } + + *_dns_domain = talloc_strdup(mem_ctx, dns_domain); + if (*_dns_domain == NULL) { + return ENOMEM; + } + + return EOK; +} + +struct resolv_discover_srv_state { + struct tevent_context *ev; + struct resolv_ctx *resolv_ctx; + const char *service; + const char *protocol; + const char **discovery_domains; + int domain_index; + + struct ares_srv_reply *reply_list; + uint32_t ttl; +}; + +static errno_t resolv_discover_srv_next_domain(struct tevent_req *req); +static void resolv_discover_srv_done(struct tevent_req *subreq); + +struct tevent_req *resolv_discover_srv_send(TALLOC_CTX *mem_ctx, + struct tevent_context *ev, + struct resolv_ctx *resolv_ctx, + const char *service, + const char *protocol, + const char **discovery_domains) +{ + struct resolv_discover_srv_state *state = NULL; + struct tevent_req *req = NULL; + errno_t ret; + + req = tevent_req_create(mem_ctx, &state, + struct resolv_discover_srv_state); + if (req == NULL) { + DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n"); + return NULL; + } + + if (resolv_ctx == NULL || service == NULL || protocol == NULL + || discovery_domains == NULL) { + ret = EINVAL; + goto immediately; + } + + state->ev = ev; + state->resolv_ctx = resolv_ctx; + state->discovery_domains = discovery_domains; + state->service = service; + state->protocol = protocol; + state->domain_index = 0; + + ret = resolv_discover_srv_next_domain(req); + if (ret != EAGAIN) { + goto immediately; + } + + return req; + +immediately: + if (ret == EOK) { + tevent_req_done(req); + } else { + tevent_req_error(req, ret); + } + tevent_req_post(req, ev); + + return req; +} + +static errno_t resolv_discover_srv_next_domain(struct tevent_req *req) +{ + struct resolv_discover_srv_state *state = NULL; + struct tevent_req *subreq = NULL; + const char *domain = NULL; + char *query = NULL; + errno_t ret; + + state = tevent_req_data(req, struct resolv_discover_srv_state); + + domain = state->discovery_domains[state->domain_index]; + if (domain == NULL) { + ret = EOK; + goto done; + } + + query = talloc_asprintf(state, "_%s._%s.%s", state->service, + state->protocol, domain); + if (query == NULL) { + ret = ENOMEM; + goto done; + } + + DEBUG(SSSDBG_TRACE_FUNC, "SRV resolution of service '%s'. Will use DNS " + "discovery domain '%s'\n", state->service, domain); + + subreq = resolv_getsrv_send(state, state->ev, + state->resolv_ctx, query); + if (subreq == NULL) { + ret = ENOMEM; + goto done; + } + + tevent_req_set_callback(subreq, resolv_discover_srv_done, req); + + state->domain_index++; + ret = EAGAIN; + +done: + if (ret != EAGAIN) { + talloc_free(query); + } + + return ret; +} + +static void resolv_discover_srv_done(struct tevent_req *subreq) +{ + struct resolv_discover_srv_state *state = NULL; + struct tevent_req *req = NULL; + int status; + errno_t ret; + + req = tevent_req_callback_data(subreq, struct tevent_req); + state = tevent_req_data(req, struct resolv_discover_srv_state); + + ret = resolv_getsrv_recv(state, subreq, &status, NULL, + &state->reply_list, &state->ttl); + talloc_zfree(subreq); + if (ret != EOK) { + DEBUG(SSSDBG_OP_FAILURE, "SRV query failed [%d]: %s\n", + status, resolv_strerror(status)); + + if (status == ARES_ENOTFOUND) { + /* continue with next discovery domain */ + ret = resolv_discover_srv_next_domain(req); + if (ret == EOK) { + /* there are no more domains to try */ + ret = ENOENT; + } + + goto done; + } + + /* critical error when fetching SRV record */ + ret = EIO; + goto done; + } + +done: + if (ret == EOK) { + tevent_req_done(req); + } else if (ret != EAGAIN) { + tevent_req_error(req, ret); + } + + return; +} + +errno_t resolv_discover_srv_recv(TALLOC_CTX *mem_ctx, + struct tevent_req *req, + struct ares_srv_reply **_reply_list, + uint32_t *_ttl, + char **_dns_domain) +{ + struct resolv_discover_srv_state *state = NULL; + char *domain = NULL; + + state = tevent_req_data(req, struct resolv_discover_srv_state); + + TEVENT_REQ_RETURN_ON_ERROR(req); + + if (_dns_domain != NULL) { + /* domain_index now points to selected domain + 1 */ + domain = talloc_strdup(mem_ctx, + state->discovery_domains[state->domain_index - 1]); + if (domain == NULL) { + return ENOMEM; + } + + *_dns_domain = domain; + } + + if (_reply_list != NULL) { + *_reply_list = talloc_steal(mem_ctx, state->reply_list); + } + + if (_ttl != NULL) { + *_ttl = state->ttl; + } + + return EOK; +} |