diff options
Diffstat (limited to 'REORG.TODO/support/resolv_test.c')
| -rw-r--r-- | REORG.TODO/support/resolv_test.c | 1202 |
1 files changed, 1202 insertions, 0 deletions
diff --git a/REORG.TODO/support/resolv_test.c b/REORG.TODO/support/resolv_test.c new file mode 100644 index 0000000000..050cd7154b --- /dev/null +++ b/REORG.TODO/support/resolv_test.c @@ -0,0 +1,1202 @@ +/* DNS test framework and libresolv redirection. + Copyright (C) 2016-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <support/resolv_test.h> + +#include <arpa/inet.h> +#include <errno.h> +#include <fcntl.h> +#include <nss.h> +#include <resolv.h> +#include <search.h> +#include <stdlib.h> +#include <string.h> +#include <support/check.h> +#include <support/namespace.h> +#include <support/support.h> +#include <support/test-driver.h> +#include <support/xsocket.h> +#include <support/xthread.h> +#include <support/xunistd.h> +#include <sys/uio.h> +#include <unistd.h> + +/* Response builder. */ + +enum + { + max_response_length = 65536 + }; + +/* List of pointers to be freed. The hash table implementation + (struct hsearch_data) does not provide a way to deallocate all + objects, so this approach is used to avoid memory leaks. */ +struct to_be_freed +{ + struct to_be_freed *next; + void *ptr; +}; + +struct resolv_response_builder +{ + const unsigned char *query_buffer; + size_t query_length; + + size_t offset; /* Bytes written so far in buffer. */ + ns_sect section; /* Current section in the DNS packet. */ + unsigned int truncate_bytes; /* Bytes to remove at end of response. */ + bool drop; /* Discard generated response. */ + bool close; /* Close TCP client connection. */ + + /* Offset of the two-byte RDATA length field in the currently + written RDATA sub-structure. 0 if no RDATA is being written. */ + size_t current_rdata_offset; + + /* Hash table for locating targets for label compression. */ + struct hsearch_data compression_offsets; + /* List of pointers which need to be freed. Used for domain names + involved in label compression. */ + struct to_be_freed *to_be_freed; + + /* Must be last. Not zeroed for performance reasons. */ + unsigned char buffer[max_response_length]; +}; + +/* Response builder. */ + +/* Add a pointer to the list of pointers to be freed when B is + deallocated. */ +static void +response_push_pointer_to_free (struct resolv_response_builder *b, void *ptr) +{ + if (ptr == NULL) + return; + struct to_be_freed *e = xmalloc (sizeof (*e)); + *e = (struct to_be_freed) {b->to_be_freed, ptr}; + b->to_be_freed = e; +} + +void +resolv_response_init (struct resolv_response_builder *b, + struct resolv_response_flags flags) +{ + if (b->offset > 0) + FAIL_EXIT1 ("response_init: called at offset %zu", b->offset); + if (b->query_length < 12) + FAIL_EXIT1 ("response_init called for a query of size %zu", + b->query_length); + if (flags.rcode > 15) + FAIL_EXIT1 ("response_init: invalid RCODE %u", flags.rcode); + + /* Copy the transaction ID. */ + b->buffer[0] = b->query_buffer[0]; + b->buffer[1] = b->query_buffer[1]; + + /* Initialize the flags. */ + b->buffer[2] = 0x80; /* Mark as response. */ + b->buffer[2] |= b->query_buffer[2] & 0x01; /* Copy the RD bit. */ + if (flags.tc) + b->buffer[2] |= 0x02; + b->buffer[3] = 0x80 | flags.rcode; /* Always set RA. */ + + /* Fill in the initial section count values. */ + b->buffer[4] = flags.qdcount >> 8; + b->buffer[5] = flags.qdcount; + b->buffer[6] = flags.ancount >> 8; + b->buffer[7] = flags.ancount; + b->buffer[8] = flags.nscount >> 8; + b->buffer[9] = flags.nscount; + b->buffer[10] = flags.adcount >> 8; + b->buffer[11] = flags.adcount; + + b->offset = 12; +} + +void +resolv_response_section (struct resolv_response_builder *b, ns_sect section) +{ + if (b->offset == 0) + FAIL_EXIT1 ("resolv_response_section: response_init not called before"); + if (section < b->section) + FAIL_EXIT1 ("resolv_response_section: cannot go back to previous section"); + b->section = section; +} + +/* Add a single byte to B. */ +static inline void +response_add_byte (struct resolv_response_builder *b, unsigned char ch) +{ + if (b->offset == max_response_length) + FAIL_EXIT1 ("DNS response exceeds 64 KiB limit"); + b->buffer[b->offset] = ch; + ++b->offset; +} + +/* Add a 16-bit word VAL to B, in big-endian format. */ +static void +response_add_16 (struct resolv_response_builder *b, uint16_t val) +{ + response_add_byte (b, val >> 8); + response_add_byte (b, val); +} + +/* Increment the pers-section record counter in the packet header. */ +static void +response_count_increment (struct resolv_response_builder *b) +{ + unsigned int offset = b->section; + offset = 4 + 2 * offset; + ++b->buffer[offset + 1]; + if (b->buffer[offset + 1] == 0) + { + /* Carry. */ + ++b->buffer[offset]; + if (b->buffer[offset] == 0) + /* Overflow. */ + FAIL_EXIT1 ("too many records in section"); + } +} + +void +resolv_response_add_question (struct resolv_response_builder *b, + const char *name, uint16_t class, uint16_t type) +{ + if (b->offset == 0) + FAIL_EXIT1 ("resolv_response_add_question: " + "resolv_response_init not called"); + if (b->section != ns_s_qd) + FAIL_EXIT1 ("resolv_response_add_question: " + "must be called in the question section"); + + resolv_response_add_name (b, name); + response_add_16 (b, type); + response_add_16 (b, class); + + response_count_increment (b); +} + +void +resolv_response_add_name (struct resolv_response_builder *b, + const char *const origname) +{ + /* Normalized name. */ + char *name; + /* Normalized name with case preserved. */ + char *name_case; + { + size_t namelen = strlen (origname); + /* Remove trailing dots. FIXME: Handle trailing quoted dots. */ + while (namelen > 0 && origname[namelen - 1] == '.') + --namelen; + name = xmalloc (namelen + 1); + name_case = xmalloc (namelen + 1); + /* Copy and convert to lowercase. FIXME: This needs to normalize + escaping as well. */ + for (size_t i = 0; i < namelen; ++i) + { + char ch = origname[i]; + name_case[i] = ch; + if ('A' <= ch && ch <= 'Z') + ch = ch - 'A' + 'a'; + name[i] = ch; + } + name[namelen] = 0; + name_case[namelen] = 0; + } + char *name_start = name; + char *name_case_start = name_case; + + bool compression = false; + while (*name) + { + /* Search for a previous name we can reference. */ + ENTRY new_entry = + { + .key = name, + .data = (void *) (uintptr_t) b->offset, + }; + + /* If the label can be a compression target because it is at a + reachable offset, add it to the hash table. */ + ACTION action; + if (b->offset < (1 << 12)) + action = ENTER; + else + action = FIND; + + /* Search for known compression offsets in the hash table. */ + ENTRY *e; + if (hsearch_r (new_entry, action, &e, &b->compression_offsets) == 0) + { + if (action == FIND && errno == ESRCH) + /* Fall through. */ + e = NULL; + else + FAIL_EXIT1 ("hsearch_r failure in name compression: %m"); + } + + /* The name is known. Reference the previous location. */ + if (e != NULL && e->data != new_entry.data) + { + size_t old_offset = (uintptr_t) e->data; + response_add_byte (b, 0xC0 | (old_offset >> 8)); + response_add_byte (b, old_offset); + compression = true; + break; + } + + /* The name does not exist yet. Write one label. First, add + room for the label length. */ + size_t buffer_label_offset = b->offset; + response_add_byte (b, 0); + + /* Copy the label. */ + while (true) + { + char ch = *name_case; + if (ch == '\0') + break; + ++name; + ++name_case; + if (ch == '.') + break; + /* FIXME: Handle escaping. */ + response_add_byte (b, ch); + } + + /* Patch in the label length. */ + size_t label_length = b->offset - buffer_label_offset - 1; + if (label_length == 0) + FAIL_EXIT1 ("empty label in name compression: %s", origname); + if (label_length > 63) + FAIL_EXIT1 ("label too long in name compression: %s", origname); + b->buffer[buffer_label_offset] = label_length; + + /* Continue with the tail of the name and the next label. */ + } + + if (compression) + { + /* If we found an immediate match for the name, we have not put + it into the hash table, and can free it immediately. */ + if (name == name_start) + free (name_start); + else + response_push_pointer_to_free (b, name_start); + } + else + { + /* Terminate the sequence of labels. With compression, this is + implicit in the compression reference. */ + response_add_byte (b, 0); + response_push_pointer_to_free (b, name_start); + } + + free (name_case_start); +} + +void +resolv_response_open_record (struct resolv_response_builder *b, + const char *name, + uint16_t class, uint16_t type, uint32_t ttl) +{ + if (b->section == ns_s_qd) + FAIL_EXIT1 ("resolv_response_open_record called in question section"); + if (b->current_rdata_offset != 0) + FAIL_EXIT1 ("resolv_response_open_record called with open record"); + + resolv_response_add_name (b, name); + response_add_16 (b, type); + response_add_16 (b, class); + response_add_16 (b, ttl >> 16); + response_add_16 (b, ttl); + + b->current_rdata_offset = b->offset; + /* Add room for the RDATA length. */ + response_add_16 (b, 0); +} + + +void +resolv_response_close_record (struct resolv_response_builder *b) +{ + size_t rdata_offset = b->current_rdata_offset; + if (rdata_offset == 0) + FAIL_EXIT1 ("response_close_record called without open record"); + size_t rdata_length = b->offset - rdata_offset - 2; + if (rdata_length > 65535) + FAIL_EXIT1 ("RDATA length %zu exceeds limit", rdata_length); + b->buffer[rdata_offset] = rdata_length >> 8; + b->buffer[rdata_offset + 1] = rdata_length; + response_count_increment (b); + b->current_rdata_offset = 0; +} + +void +resolv_response_add_data (struct resolv_response_builder *b, + const void *data, size_t length) +{ + size_t remaining = max_response_length - b->offset; + if (remaining < length) + FAIL_EXIT1 ("resolv_response_add_data: not enough room for %zu bytes", + length); + memcpy (b->buffer + b->offset, data, length); + b->offset += length; +} + +void +resolv_response_drop (struct resolv_response_builder *b) +{ + b->drop = true; +} + +void +resolv_response_close (struct resolv_response_builder *b) +{ + b->close = true; +} + +void +resolv_response_truncate_data (struct resolv_response_builder *b, size_t count) +{ + if (count > 65535) + FAIL_EXIT1 ("resolv_response_truncate_data: argument too large: %zu", + count); + b->truncate_bytes = count; +} + + +size_t +resolv_response_length (const struct resolv_response_builder *b) +{ + return b->offset; +} + +unsigned char * +resolv_response_buffer (const struct resolv_response_builder *b) +{ + unsigned char *result = xmalloc (b->offset); + memcpy (result, b->buffer, b->offset); + return result; +} + +static struct resolv_response_builder * +response_builder_allocate + (const unsigned char *query_buffer, size_t query_length) +{ + struct resolv_response_builder *b = xmalloc (sizeof (*b)); + memset (b, 0, offsetof (struct resolv_response_builder, buffer)); + b->query_buffer = query_buffer; + b->query_length = query_length; + TEST_VERIFY_EXIT (hcreate_r (10000, &b->compression_offsets) != 0); + return b; +} + +static void +response_builder_free (struct resolv_response_builder *b) +{ + struct to_be_freed *current = b->to_be_freed; + while (current != NULL) + { + struct to_be_freed *next = current->next; + free (current->ptr); + free (current); + current = next; + } + hdestroy_r (&b->compression_offsets); + free (b); +} + +/* DNS query processing. */ + +/* Data extracted from the question section of a DNS packet. */ +struct query_info +{ + char qname[MAXDNAME]; + uint16_t qclass; + uint16_t qtype; + struct resolv_edns_info edns; +}; + +/* Update *INFO from the specified DNS packet. */ +static void +parse_query (struct query_info *info, + const unsigned char *buffer, size_t length) +{ + HEADER hd; + _Static_assert (sizeof (hd) == 12, "DNS header size"); + if (length < sizeof (hd)) + FAIL_EXIT1 ("malformed DNS query: too short: %zu bytes", length); + memcpy (&hd, buffer, sizeof (hd)); + + if (ntohs (hd.qdcount) != 1) + FAIL_EXIT1 ("malformed DNS query: wrong question count: %d", + (int) ntohs (hd.qdcount)); + if (ntohs (hd.ancount) != 0) + FAIL_EXIT1 ("malformed DNS query: wrong answer count: %d", + (int) ntohs (hd.ancount)); + if (ntohs (hd.nscount) != 0) + FAIL_EXIT1 ("malformed DNS query: wrong authority count: %d", + (int) ntohs (hd.nscount)); + if (ntohs (hd.arcount) > 1) + FAIL_EXIT1 ("malformed DNS query: wrong additional count: %d", + (int) ntohs (hd.arcount)); + + int ret = dn_expand (buffer, buffer + length, buffer + sizeof (hd), + info->qname, sizeof (info->qname)); + if (ret < 0) + FAIL_EXIT1 ("malformed DNS query: cannot uncompress QNAME"); + + /* Obtain QTYPE and QCLASS. */ + size_t remaining = length - (12 + ret); + struct + { + uint16_t qtype; + uint16_t qclass; + } qtype_qclass; + if (remaining < sizeof (qtype_qclass)) + FAIL_EXIT1 ("malformed DNS query: " + "query lacks QCLASS/QTYPE, QNAME: %s", info->qname); + memcpy (&qtype_qclass, buffer + 12 + ret, sizeof (qtype_qclass)); + info->qclass = ntohs (qtype_qclass.qclass); + info->qtype = ntohs (qtype_qclass.qtype); + + memset (&info->edns, 0, sizeof (info->edns)); + if (ntohs (hd.arcount) > 0) + { + /* Parse EDNS record. */ + struct __attribute__ ((packed, aligned (1))) + { + uint8_t root; + uint16_t rtype; + uint16_t payload; + uint8_t edns_extended_rcode; + uint8_t edns_version; + uint16_t flags; + uint16_t rdatalen; + } rr; + _Static_assert (sizeof (rr) == 11, "EDNS record size"); + + if (remaining < 4 + sizeof (rr)) + FAIL_EXIT1 ("mailformed DNS query: no room for EDNS record"); + memcpy (&rr, buffer + 12 + ret + 4, sizeof (rr)); + if (rr.root != 0) + FAIL_EXIT1 ("malformed DNS query: invalid OPT RNAME: %d\n", rr.root); + if (rr.rtype != htons (41)) + FAIL_EXIT1 ("malformed DNS query: invalid OPT type: %d\n", + ntohs (rr.rtype)); + info->edns.active = true; + info->edns.extended_rcode = rr.edns_extended_rcode; + info->edns.version = rr.edns_version; + info->edns.flags = ntohs (rr.flags); + info->edns.payload_size = ntohs (rr.payload); + } +} + + +/* Main testing framework. */ + +/* Per-server information. One struct is allocated for each test + server. */ +struct resolv_test_server +{ + /* Local address of the server. UDP and TCP use the same port. */ + struct sockaddr_in address; + + /* File descriptor of the UDP server, or -1 if this server is + disabled. */ + int socket_udp; + + /* File descriptor of the TCP server, or -1 if this server is + disabled. */ + int socket_tcp; + + /* Counter of the number of responses processed so far. */ + size_t response_number; + + /* Thread handles for the server threads (if not disabled in the + configuration). */ + pthread_t thread_udp; + pthread_t thread_tcp; +}; + +/* Main struct for keeping track of libresolv redirection and + testing. */ +struct resolv_test +{ + /* After initialization, any access to the struct must be performed + while this lock is acquired. */ + pthread_mutex_t lock; + + /* Data for each test server. */ + struct resolv_test_server servers[resolv_max_test_servers]; + + /* Used if config.single_thread_udp is true. */ + pthread_t thread_udp_single; + + struct resolv_redirect_config config; + bool termination_requested; +}; + +/* Function implementing a server thread. */ +typedef void (*thread_callback) (struct resolv_test *, int server_index); + +/* Storage for thread-specific data, for passing to the + thread_callback function. */ +struct thread_closure +{ + struct resolv_test *obj; /* Current test object. */ + thread_callback callback; /* Function to call. */ + int server_index; /* Index of the implemented server. */ +}; + +/* Wrap response_callback as a function which can be passed to + pthread_create. */ +static void * +thread_callback_wrapper (void *arg) +{ + struct thread_closure *closure = arg; + closure->callback (closure->obj, closure->server_index); + free (closure); + return NULL; +} + +/* Start a server thread for the specified SERVER_INDEX, implemented + by CALLBACK. */ +static pthread_t +start_server_thread (struct resolv_test *obj, int server_index, + thread_callback callback) +{ + struct thread_closure *closure = xmalloc (sizeof (*closure)); + *closure = (struct thread_closure) + { + .obj = obj, + .callback = callback, + .server_index = server_index, + }; + return xpthread_create (NULL, thread_callback_wrapper, closure); +} + +/* Process one UDP query. Return false if a termination requested has + been detected. */ +static bool +server_thread_udp_process_one (struct resolv_test *obj, int server_index) +{ + unsigned char query[512]; + struct sockaddr_storage peer; + socklen_t peerlen = sizeof (peer); + size_t length = xrecvfrom (obj->servers[server_index].socket_udp, + query, sizeof (query), 0, + (struct sockaddr *) &peer, &peerlen); + /* Check for termination. */ + { + bool termination_requested; + xpthread_mutex_lock (&obj->lock); + termination_requested = obj->termination_requested; + xpthread_mutex_unlock (&obj->lock); + if (termination_requested) + return false; + } + + + struct query_info qinfo; + parse_query (&qinfo, query, length); + if (test_verbose > 0) + { + if (test_verbose > 1) + printf ("info: UDP server %d: incoming query:" + " %zd bytes, %s/%u/%u, tnxid=0x%02x%02x\n", + server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype, + query[0], query[1]); + else + printf ("info: UDP server %d: incoming query:" + " %zd bytes, %s/%u/%u\n", + server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype); + } + + struct resolv_response_context ctx = + { + .query_buffer = query, + .query_length = length, + .server_index = server_index, + .tcp = false, + .edns = qinfo.edns, + }; + struct resolv_response_builder *b = response_builder_allocate (query, length); + obj->config.response_callback + (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype); + + if (b->drop) + { + if (test_verbose) + printf ("info: UDP server %d: dropping response to %s/%u/%u\n", + server_index, qinfo.qname, qinfo.qclass, qinfo.qtype); + } + else + { + if (test_verbose) + { + if (b->offset >= 12) + printf ("info: UDP server %d: sending response:" + " %zu bytes, RCODE %d (for %s/%u/%u)\n", + server_index, b->offset, b->buffer[3] & 0x0f, + qinfo.qname, qinfo.qclass, qinfo.qtype); + else + printf ("info: UDP server %d: sending response: %zu bytes" + " (for %s/%u/%u)\n", + server_index, b->offset, + qinfo.qname, qinfo.qclass, qinfo.qtype); + if (b->truncate_bytes > 0) + printf ("info: truncated by %u bytes\n", b->truncate_bytes); + } + size_t to_send = b->offset; + if (to_send < b->truncate_bytes) + to_send = 0; + else + to_send -= b->truncate_bytes; + + /* Ignore most errors here because the other end may have closed + the socket. */ + if (sendto (obj->servers[server_index].socket_udp, + b->buffer, to_send, 0, + (struct sockaddr *) &peer, peerlen) < 0) + TEST_VERIFY_EXIT (errno != EBADF); + } + response_builder_free (b); + return true; +} + +/* UDP thread_callback function. Variant for one thread per + server. */ +static void +server_thread_udp (struct resolv_test *obj, int server_index) +{ + while (server_thread_udp_process_one (obj, server_index)) + ; +} + +/* Single-threaded UDP processing function, for the single_thread_udp + case. */ +static void * +server_thread_udp_single (void *closure) +{ + struct resolv_test *obj = closure; + + struct pollfd fds[resolv_max_test_servers]; + for (int server_index = 0; server_index < resolv_max_test_servers; + ++server_index) + if (obj->config.servers[server_index].disable_udp) + fds[server_index] = (struct pollfd) {.fd = -1}; + else + { + fds[server_index] = (struct pollfd) + { + .fd = obj->servers[server_index].socket_udp, + .events = POLLIN + }; + + /* Make the socket non-blocking. */ + int flags = fcntl (obj->servers[server_index].socket_udp, F_GETFL, 0); + if (flags < 0) + FAIL_EXIT1 ("fcntl (F_GETFL): %m"); + flags |= O_NONBLOCK; + if (fcntl (obj->servers[server_index].socket_udp, F_SETFL, flags) < 0) + FAIL_EXIT1 ("fcntl (F_SETFL): %m"); + } + + while (true) + { + xpoll (fds, resolv_max_test_servers, -1); + for (int server_index = 0; server_index < resolv_max_test_servers; + ++server_index) + if (fds[server_index].revents != 0) + { + if (!server_thread_udp_process_one (obj, server_index)) + goto out; + fds[server_index].revents = 0; + } + } + + out: + return NULL; +} + +/* Start the single UDP handler thread (for the single_thread_udp + case). */ +static void +start_server_thread_udp_single (struct resolv_test *obj) +{ + obj->thread_udp_single + = xpthread_create (NULL, server_thread_udp_single, obj); +} + +/* Data describing a TCP client connect. */ +struct tcp_thread_closure +{ + struct resolv_test *obj; + int server_index; + int client_socket; +}; + +/* Read a complete DNS query packet. If EOF_OK, an immediate + end-of-file condition is acceptable. */ +static bool +read_fully (int fd, void *buf, size_t len, bool eof_ok) +{ + const void *const end = buf + len; + while (buf < end) + { + ssize_t ret = read (fd, buf, end - buf); + if (ret == 0) + { + if (!eof_ok) + { + support_record_failure (); + printf ("error: unexpected EOF on TCP connection\n"); + } + return false; + } + else if (ret < 0) + { + if (!eof_ok || errno != ECONNRESET) + { + support_record_failure (); + printf ("error: TCP read: %m\n"); + } + return false; + } + buf += ret; + eof_ok = false; + } + return true; +} + +/* Write an array of iovecs. Terminate the process on failure. */ +static void +writev_fully (int fd, struct iovec *buffers, size_t count) +{ + while (count > 0) + { + /* Skip zero-length write requests. */ + if (buffers->iov_len == 0) + { + ++buffers; + --count; + continue; + } + /* Try to rewrite the remaing buffers. */ + ssize_t ret = writev (fd, buffers, count); + if (ret < 0) + FAIL_EXIT1 ("writev: %m"); + if (ret == 0) + FAIL_EXIT1 ("writev: invalid return value zero"); + /* Find the buffers that were successfully written. */ + while (ret > 0) + { + if (count == 0) + FAIL_EXIT1 ("internal writev consistency failure"); + /* Current buffer was partially written. */ + if (buffers->iov_len > (size_t) ret) + { + buffers->iov_base += ret; + buffers->iov_len -= ret; + ret = 0; + } + else + { + ret -= buffers->iov_len; + buffers->iov_len = 0; + ++buffers; + --count; + } + } + } +} + +/* Thread callback for handling a single established TCP connection to + a client. */ +static void * +server_thread_tcp_client (void *arg) +{ + struct tcp_thread_closure *closure = arg; + + while (true) + { + /* Read packet length. */ + uint16_t query_length; + if (!read_fully (closure->client_socket, + &query_length, sizeof (query_length), true)) + break; + query_length = ntohs (query_length); + + /* Read the packet. */ + unsigned char *query_buffer = xmalloc (query_length); + read_fully (closure->client_socket, query_buffer, query_length, false); + + struct query_info qinfo; + parse_query (&qinfo, query_buffer, query_length); + if (test_verbose > 0) + { + if (test_verbose > 1) + printf ("info: UDP server %d: incoming query:" + " %d bytes, %s/%u/%u, tnxid=0x%02x%02x\n", + closure->server_index, query_length, + qinfo.qname, qinfo.qclass, qinfo.qtype, + query_buffer[0], query_buffer[1]); + else + printf ("info: TCP server %d: incoming query:" + " %u bytes, %s/%u/%u\n", + closure->server_index, query_length, + qinfo.qname, qinfo.qclass, qinfo.qtype); + } + + struct resolv_response_context ctx = + { + .query_buffer = query_buffer, + .query_length = query_length, + .server_index = closure->server_index, + .tcp = true, + .edns = qinfo.edns, + }; + struct resolv_response_builder *b = response_builder_allocate + (query_buffer, query_length); + closure->obj->config.response_callback + (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype); + + if (b->drop) + { + if (test_verbose) + printf ("info: TCP server %d: dropping response to %s/%u/%u\n", + closure->server_index, + qinfo.qname, qinfo.qclass, qinfo.qtype); + } + else + { + if (test_verbose) + printf ("info: TCP server %d: sending response: %zu bytes" + " (for %s/%u/%u)\n", + closure->server_index, b->offset, + qinfo.qname, qinfo.qclass, qinfo.qtype); + uint16_t length = htons (b->offset); + size_t to_send = b->offset; + if (to_send < b->truncate_bytes) + to_send = 0; + else + to_send -= b->truncate_bytes; + struct iovec buffers[2] = + { + {&length, sizeof (length)}, + {b->buffer, to_send} + }; + writev_fully (closure->client_socket, buffers, 2); + } + bool close_flag = b->close; + response_builder_free (b); + free (query_buffer); + if (close_flag) + break; + } + + xclose (closure->client_socket); + free (closure); + return NULL; +} + +/* thread_callback for the TCP case. Accept connections and create a + new thread for each client. */ +static void +server_thread_tcp (struct resolv_test *obj, int server_index) +{ + while (true) + { + /* Get the client conenction. */ + int client_socket = xaccept + (obj->servers[server_index].socket_tcp, NULL, NULL); + + /* Check for termination. */ + xpthread_mutex_lock (&obj->lock); + if (obj->termination_requested) + { + xpthread_mutex_unlock (&obj->lock); + xclose (client_socket); + break; + } + xpthread_mutex_unlock (&obj->lock); + + /* Spawn a new thread for handling this connection. */ + struct tcp_thread_closure *closure = xmalloc (sizeof (*closure)); + *closure = (struct tcp_thread_closure) + { + .obj = obj, + .server_index = server_index, + .client_socket = client_socket, + }; + + pthread_t thr + = xpthread_create (NULL, server_thread_tcp_client, closure); + /* TODO: We should keep track of this thread so that we can + block in resolv_test_end until it has exited. */ + xpthread_detach (thr); + } +} + +/* Create UDP and TCP server sockets. */ +static void +make_server_sockets (struct resolv_test_server *server) +{ + while (true) + { + server->socket_udp = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP); + server->socket_tcp = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP); + + /* Pick the address for the UDP socket. */ + server->address = (struct sockaddr_in) + { + .sin_family = AF_INET, + .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK)} + }; + xbind (server->socket_udp, + (struct sockaddr *)&server->address, sizeof (server->address)); + + /* Retrieve the address. */ + socklen_t addrlen = sizeof (server->address); + xgetsockname (server->socket_udp, + (struct sockaddr *)&server->address, &addrlen); + + /* Bind the TCP socket to the same address. */ + { + int on = 1; + xsetsockopt (server->socket_tcp, SOL_SOCKET, SO_REUSEADDR, + &on, sizeof (on)); + } + if (bind (server->socket_tcp, + (struct sockaddr *)&server->address, + sizeof (server->address)) != 0) + { + /* Port collision. The UDP bind succeeded, but the TCP BIND + failed. We assume here that the kernel will pick the + next local UDP address randomly. */ + if (errno == EADDRINUSE) + { + xclose (server->socket_udp); + xclose (server->socket_tcp); + continue; + } + FAIL_EXIT1 ("TCP bind: %m"); + } + xlisten (server->socket_tcp, 5); + break; + } +} + +/* One-time initialization of NSS. */ +static void +resolv_redirect_once (void) +{ + /* Only use nss_dns. */ + __nss_configure_lookup ("hosts", "dns"); + __nss_configure_lookup ("networks", "dns"); + /* Enter a network namespace for isolation and firewall state + cleanup. The tests will still work if these steps fail, but they + may be less reliable. */ + support_become_root (); + support_enter_network_namespace (); +} +pthread_once_t resolv_redirect_once_var = PTHREAD_ONCE_INIT; + +void +resolv_test_init (void) +{ + /* Perform one-time initialization of NSS. */ + xpthread_once (&resolv_redirect_once_var, resolv_redirect_once); +} + +/* Copy the search path from CONFIG.search to the _res object. */ +static void +set_search_path (struct resolv_redirect_config config) +{ + memset (_res.defdname, 0, sizeof (_res.defdname)); + memset (_res.dnsrch, 0, sizeof (_res.dnsrch)); + + char *current = _res.defdname; + char *end = current + sizeof (_res.defdname); + + for (unsigned int i = 0; + i < sizeof (config.search) / sizeof (config.search[0]); ++i) + { + if (config.search[i] == NULL) + continue; + + size_t length = strlen (config.search[i]) + 1; + size_t remaining = end - current; + TEST_VERIFY_EXIT (length <= remaining); + memcpy (current, config.search[i], length); + _res.dnsrch[i] = current; + current += length; + } +} + +struct resolv_test * +resolv_test_start (struct resolv_redirect_config config) +{ + /* Apply configuration defaults. */ + if (config.nscount == 0) + config.nscount = resolv_max_test_servers; + + struct resolv_test *obj = xmalloc (sizeof (*obj)); + *obj = (struct resolv_test) { + .config = config, + .lock = PTHREAD_MUTEX_INITIALIZER, + }; + + resolv_test_init (); + + /* Create all the servers, to reserve the necessary ports. */ + for (int server_index = 0; server_index < config.nscount; ++server_index) + make_server_sockets (obj->servers + server_index); + + /* Start server threads. Disable the server ports, as + requested. */ + for (int server_index = 0; server_index < config.nscount; ++server_index) + { + struct resolv_test_server *server = obj->servers + server_index; + if (config.servers[server_index].disable_udp) + { + xclose (server->socket_udp); + server->socket_udp = -1; + } + else if (!config.single_thread_udp) + server->thread_udp = start_server_thread (obj, server_index, + server_thread_udp); + if (config.servers[server_index].disable_tcp) + { + xclose (server->socket_tcp); + server->socket_tcp = -1; + } + else + server->thread_tcp = start_server_thread (obj, server_index, + server_thread_tcp); + } + if (config.single_thread_udp) + start_server_thread_udp_single (obj); + + int timeout = 1; + + /* Initialize libresolv. */ + TEST_VERIFY_EXIT (res_init () == 0); + + /* Disable IPv6 name server addresses. The code below only + overrides the IPv4 addresses. */ + __res_iclose (&_res, true); + _res._u._ext.nscount = 0; + + /* Redirect queries to the server socket. */ + if (test_verbose) + { + printf ("info: old timeout value: %d\n", _res.retrans); + printf ("info: old retry attempt value: %d\n", _res.retry); + printf ("info: old _res.options: 0x%lx\n", _res.options); + printf ("info: old _res.nscount value: %d\n", _res.nscount); + printf ("info: old _res.ndots value: %d\n", _res.ndots); + } + _res.retrans = timeout; + _res.retry = 4; + _res.nscount = config.nscount; + _res.options = RES_INIT | RES_RECURSE | RES_DEFNAMES | RES_DNSRCH; + _res.ndots = 1; + if (test_verbose) + { + printf ("info: new timeout value: %d\n", _res.retrans); + printf ("info: new retry attempt value: %d\n", _res.retry); + printf ("info: new _res.options: 0x%lx\n", _res.options); + printf ("info: new _res.nscount value: %d\n", _res.nscount); + printf ("info: new _res.ndots value: %d\n", _res.ndots); + } + for (int server_index = 0; server_index < config.nscount; ++server_index) + { + _res.nsaddr_list[server_index] = obj->servers[server_index].address; + if (test_verbose) + { + char buf[256]; + TEST_VERIFY_EXIT + (inet_ntop (AF_INET, &obj->servers[server_index].address.sin_addr, + buf, sizeof (buf)) != NULL); + printf ("info: server %d: %s/%u\n", + server_index, buf, + htons (obj->servers[server_index].address.sin_port)); + } + } + + set_search_path (config); + + return obj; +} + +void +resolv_test_end (struct resolv_test *obj) +{ + res_close (); + + xpthread_mutex_lock (&obj->lock); + obj->termination_requested = true; + xpthread_mutex_unlock (&obj->lock); + + /* Send trigger packets to unblock the server threads. */ + for (int server_index = 0; server_index < obj->config.nscount; + ++server_index) + { + if (!obj->config.servers[server_index].disable_udp) + { + int sock = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP); + xsendto (sock, "", 1, 0, + (struct sockaddr *) &obj->servers[server_index].address, + sizeof (obj->servers[server_index].address)); + xclose (sock); + } + if (!obj->config.servers[server_index].disable_tcp) + { + int sock = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP); + xconnect (sock, + (struct sockaddr *) &obj->servers[server_index].address, + sizeof (obj->servers[server_index].address)); + xclose (sock); + } + } + + if (obj->config.single_thread_udp) + xpthread_join (obj->thread_udp_single); + + /* Wait for the server threads to terminate. */ + for (int server_index = 0; server_index < obj->config.nscount; + ++server_index) + { + if (!obj->config.servers[server_index].disable_udp) + { + if (!obj->config.single_thread_udp) + xpthread_join (obj->servers[server_index].thread_udp); + xclose (obj->servers[server_index].socket_udp); + } + if (!obj->config.servers[server_index].disable_tcp) + { + xpthread_join (obj->servers[server_index].thread_tcp); + xclose (obj->servers[server_index].socket_tcp); + } + } + + free (obj); +} |