diff options
Diffstat (limited to 'modules/metadata/mod_unique_id.c')
| -rw-r--r-- | modules/metadata/mod_unique_id.c | 402 |
1 files changed, 0 insertions, 402 deletions
diff --git a/modules/metadata/mod_unique_id.c b/modules/metadata/mod_unique_id.c deleted file mode 100644 index 69a54174b4..0000000000 --- a/modules/metadata/mod_unique_id.c +++ /dev/null @@ -1,402 +0,0 @@ -/* ==================================================================== - * The Apache Software License, Version 1.1 - * - * Copyright (c) 2000-2001 The Apache Software Foundation. All rights - * reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in - * the documentation and/or other materials provided with the - * distribution. - * - * 3. The end-user documentation included with the redistribution, - * if any, must include the following acknowledgment: - * "This product includes software developed by the - * Apache Software Foundation (http://www.apache.org/)." - * Alternately, this acknowledgment may appear in the software itself, - * if and wherever such third-party acknowledgments normally appear. - * - * 4. The names "Apache" and "Apache Software Foundation" must - * not be used to endorse or promote products derived from this - * software without prior written permission. For written - * permission, please contact apache@apache.org. - * - * 5. Products derived from this software may not be called "Apache", - * nor may "Apache" appear in their name, without prior written - * permission of the Apache Software Foundation. - * - * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED - * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES - * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE - * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR - * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF - * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND - * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, - * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT - * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - * ==================================================================== - * - * This software consists of voluntary contributions made by many - * individuals on behalf of the Apache Software Foundation. For more - * information on the Apache Software Foundation, please see - * <http://www.apache.org/>. - * - * Portions of this software are based upon public domain software - * originally written at the National Center for Supercomputing Applications, - * University of Illinois, Urbana-Champaign. - */ - -/* - * mod_unique_id.c: generate a unique identifier for each request - * - * Original author: Dean Gaudet <dgaudet@arctic.org> - * UUencoding modified by: Alvaro Martinez Echevarria <alvaro@lander.es> - */ - -#include "apr_general.h" /* for XtOffsetOf */ - -#include "httpd.h" -#include "http_config.h" -#include "http_log.h" -#include "http_protocol.h" /* for ap_hook_post_read_request */ - -#if APR_HAVE_NETDB_H -#include <netdb.h> -#endif -#if APR_HAVE_ARPA_INET_H -#include <arpa/inet.h> -#endif -#if APR_HAVE_UNISTD_H -#include <unistd.h> -#endif - -typedef struct { - unsigned int stamp; - unsigned int in_addr; - unsigned int pid; - unsigned short counter; - unsigned int thread_index; -} unique_id_rec; - -/* We are using thread_index (the index into the scoreboard), because we - * cannont garauntee the thread_id will be an integer. - * - * This code looks like it won't give a unique ID with the new thread logic. - * It will. The reason is, we don't increment the counter in a thread_safe - * manner. Because the thread_index is also in the unique ID now, this does - * not matter. In order for the id to not be unique, the same thread would - * have to get the same counter twice in the same second. - */ - -/* Comments: - * - * We want an identifier which is unique across all hits, everywhere. - * "everywhere" includes multiple httpd instances on the same machine, or on - * multiple machines. Essentially "everywhere" should include all possible - * httpds across all servers at a particular "site". We make some assumptions - * that if the site has a cluster of machines then their time is relatively - * synchronized. We also assume that the first address returned by a - * gethostbyname (gethostname()) is unique across all the machines at the - * "site". - * - * We also further assume that pids fit in 32-bits. If something uses more - * than 32-bits, the fix is trivial, but it requires the unrolled uuencoding - * loop to be extended. * A similar fix is needed to support multithreaded - * servers, using a pid/tid combo. - * - * Together, the in_addr and pid are assumed to absolutely uniquely identify - * this one child from all other currently running children on all servers - * (including this physical server if it is running multiple httpds) from each - * other. - * - * The stamp and counter are used to distinguish all hits for a particular - * (in_addr,pid) pair. The stamp is updated using r->request_time, - * saving cpu cycles. The counter is never reset, and is used to permit up to - * 64k requests in a single second by a single child. - * - * The 112-bits of unique_id_rec are encoded using the alphabet - * [A-Za-z0-9@-], resulting in 19 bytes of printable characters. That is then - * stuffed into the environment variable UNIQUE_ID so that it is available to - * other modules. The alphabet choice differs from normal base64 encoding - * [A-Za-z0-9+/] because + and / are special characters in URLs and we want to - * make it easy to use UNIQUE_ID in URLs. - * - * Note that UNIQUE_ID should be considered an opaque token by other - * applications. No attempt should be made to dissect its internal components. - * It is an abstraction that may change in the future as the needs of this - * module change. - * - * It is highly desirable that identifiers exist for "eternity". But future - * needs (such as much faster webservers, moving to 64-bit pids, or moving to a - * multithreaded server) may dictate a need to change the contents of - * unique_id_rec. Such a future implementation should ensure that the first - * field is still a time_t stamp. By doing that, it is possible for a site to - * have a "flag second" in which they stop all of their old-format servers, - * wait one entire second, and then start all of their new-servers. This - * procedure will ensure that the new space of identifiers is completely unique - * from the old space. (Since the first four unencoded bytes always differ.) - */ -/* - * Sun Jun 7 05:43:49 CEST 1998 -- Alvaro - * More comments: - * 1) The UUencoding prodecure is now done in a general way, avoiding the problems - * with sizes and paddings that can arise depending on the architecture. Now the - * offsets and sizes of the elements of the unique_id_rec structure are calculated - * in unique_id_global_init; and then used to duplicate the structure without the - * paddings that might exist. The multithreaded server fix should be now very easy: - * just add a new "tid" field to the unique_id_rec structure, and increase by one - * UNIQUE_ID_REC_MAX. - * 2) unique_id_rec.stamp has been changed from "time_t" to "unsigned int", because - * its size is 64bits on some platforms (linux/alpha), and this caused problems with - * htonl/ntohl. Well, this shouldn't be a problem till year 2106. - */ - -static unsigned global_in_addr; - -static unique_id_rec cur_unique_id; - -/* - * Number of elements in the structure unique_id_rec. - */ -#define UNIQUE_ID_REC_MAX 5 - -static unsigned short unique_id_rec_offset[UNIQUE_ID_REC_MAX], - unique_id_rec_size[UNIQUE_ID_REC_MAX], - unique_id_rec_total_size, - unique_id_rec_size_uu; - -static void unique_id_global_init(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *main_server) -{ -#ifndef MAXHOSTNAMELEN -#define MAXHOSTNAMELEN 256 -#endif - char str[MAXHOSTNAMELEN + 1]; - struct hostent *hent; - apr_short_interval_time_t pause; - - /* - * Calculate the sizes and offsets in cur_unique_id. - */ - unique_id_rec_offset[0] = XtOffsetOf(unique_id_rec, stamp); - unique_id_rec_size[0] = sizeof(cur_unique_id.stamp); - unique_id_rec_offset[1] = XtOffsetOf(unique_id_rec, in_addr); - unique_id_rec_size[1] = sizeof(cur_unique_id.in_addr); - unique_id_rec_offset[2] = XtOffsetOf(unique_id_rec, pid); - unique_id_rec_size[2] = sizeof(cur_unique_id.pid); - unique_id_rec_offset[3] = XtOffsetOf(unique_id_rec, counter); - unique_id_rec_size[3] = sizeof(cur_unique_id.counter); - unique_id_rec_offset[4] = XtOffsetOf(unique_id_rec, thread_index); - unique_id_rec_size[4] = sizeof(cur_unique_id.thread_index); - unique_id_rec_total_size = unique_id_rec_size[0] + unique_id_rec_size[1] + - unique_id_rec_size[2] + unique_id_rec_size[3] + - unique_id_rec_size[4]; - - /* - * Calculate the size of the structure when encoded. - */ - unique_id_rec_size_uu = (unique_id_rec_total_size*8+5)/6; - - /* - * Now get the global in_addr. Note that it is not sufficient to use one - * of the addresses from the main_server, since those aren't as likely to - * be unique as the physical address of the machine - */ - if (gethostname(str, sizeof(str) - 1) != 0) { - ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ALERT, errno, main_server, - "gethostname: mod_unique_id requires the hostname of the server"); - exit(1); - } - str[sizeof(str) - 1] = '\0'; - - if ((hent = gethostbyname(str)) == NULL) { - ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ALERT, h_errno, main_server, - "mod_unique_id: unable to gethostbyname(\"%s\")", str); - exit(1); - } - - global_in_addr = ((struct in_addr *) hent->h_addr_list[0])->s_addr; - - ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_INFO, 0, main_server, - "mod_unique_id: using ip addr %s", - inet_ntoa(*(struct in_addr *) hent->h_addr_list[0])); - - /* - * If the server is pummelled with restart requests we could possibly end - * up in a situation where we're starting again during the same second - * that has been used in previous identifiers. Avoid that situation. - * - * In truth, for this to actually happen not only would it have to restart - * in the same second, but it would have to somehow get the same pids as - * one of the other servers that was running in that second. Which would - * mean a 64k wraparound on pids ... not very likely at all. - * - * But protecting against it is relatively cheap. We just sleep into the - * next second. - */ - pause = (apr_short_interval_time_t)(1000000 - (apr_time_now() % APR_USEC_PER_SEC)); - apr_sleep(pause); -} - -static void unique_id_child_init(apr_pool_t *p, server_rec *s) -{ - pid_t pid; - apr_time_t tv; - - /* - * Note that we use the pid because it's possible that on the same - * physical machine there are multiple servers (i.e. using Listen). But - * it's guaranteed that none of them will share the same pids between - * children. - * - * XXX: for multithread this needs to use a pid/tid combo and probably - * needs to be expanded to 32 bits - */ - pid = getpid(); - cur_unique_id.pid = pid; - - /* - * Test our assumption that the pid is 32-bits. It's possible that - * 64-bit machines will declare pid_t to be 64 bits but only use 32 - * of them. It would have been really nice to test this during - * global_init ... but oh well. - */ - if (cur_unique_id.pid != pid) { - ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_CRIT, 0, s, - "oh no! pids are greater than 32-bits! I'm broken!"); - } - - cur_unique_id.in_addr = global_in_addr; - - /* - * If we use 0 as the initial counter we have a little less protection - * against restart problems, and a little less protection against a clock - * going backwards in time. - */ - tv = apr_time_now(); - /* Some systems have very low variance on the low end of their system - * counter, defend against that. - */ - cur_unique_id.counter = tv % APR_USEC_PER_SEC / 10; - - /* - * We must always use network ordering for these bytes, so that - * identifiers are comparable between machines of different byte - * orderings. Note in_addr is already in network order. - */ - cur_unique_id.pid = htonl(cur_unique_id.pid); - cur_unique_id.counter = htons(cur_unique_id.counter); -} - -/* NOTE: This is *NOT* the same encoding used by base64encode ... the last two - * characters should be + and /. But those two characters have very special - * meanings in URLs, and we want to make it easy to use identifiers in - * URLs. So we replace them with @ and -. - */ -static const char uuencoder[64] = { - 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', - 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', - 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', - 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', - '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '@', '-', -}; - -static int gen_unique_id(request_rec *r) -{ - char *str; - /* - * Buffer padded with two final bytes, used to copy the unique_id_red - * structure without the internal paddings that it could have. - */ - unique_id_rec new_unique_id; - struct { - unique_id_rec foo; - unsigned char pad[2]; - } paddedbuf; - unsigned char *x,*y; - unsigned short counter; - const char *e; - int i,j,k; - - /* copy the unique_id if this is an internal redirect (we're never - * actually called for sub requests, so we don't need to test for - * them) */ - if (r->prev && (e = apr_table_get(r->subprocess_env, "REDIRECT_UNIQUE_ID"))) { - apr_table_setn(r->subprocess_env, "UNIQUE_ID", e); - return DECLINED; - } - - new_unique_id.in_addr = cur_unique_id.in_addr; - new_unique_id.pid = cur_unique_id.pid; - new_unique_id.counter = cur_unique_id.counter; - - new_unique_id.stamp = htonl((unsigned int)r->request_time); - new_unique_id.thread_index = htonl((unsigned int)r->connection->id); - - /* we'll use a temporal buffer to avoid uuencoding the possible internal - * paddings of the original structure */ - x = (unsigned char *) &paddedbuf; - y = (unsigned char *) &new_unique_id; - k = 0; - for (i = 0; i < UNIQUE_ID_REC_MAX; i++) { - y = ((unsigned char *) &new_unique_id) + unique_id_rec_offset[i]; - for (j = 0; j < unique_id_rec_size[i]; j++, k++) { - x[k] = y[j]; - } - } - /* - * We reset two more bytes just in case padding is needed for the uuencoding. - */ - x[k++] = '\0'; - x[k++] = '\0'; - - /* alloc str and do the uuencoding */ - str = (char *)apr_palloc(r->pool, unique_id_rec_size_uu + 1); - k = 0; - for (i = 0; i < unique_id_rec_total_size; i += 3) { - y = x + i; - str[k++] = uuencoder[y[0] >> 2]; - str[k++] = uuencoder[((y[0] & 0x03) << 4) | ((y[1] & 0xf0) >> 4)]; - if (k == unique_id_rec_size_uu) break; - str[k++] = uuencoder[((y[1] & 0x0f) << 2) | ((y[2] & 0xc0) >> 6)]; - if (k == unique_id_rec_size_uu) break; - str[k++] = uuencoder[y[2] & 0x3f]; - } - str[k++] = '\0'; - - /* set the environment variable */ - apr_table_setn(r->subprocess_env, "UNIQUE_ID", str); - - /* and increment the identifier for the next call */ - - counter = ntohs(new_unique_id.counter) + 1; - cur_unique_id.counter = htons(counter); - - return DECLINED; -} - -static void register_hooks(apr_pool_t *p) -{ - ap_hook_post_config(unique_id_global_init, NULL, NULL, APR_HOOK_MIDDLE); - ap_hook_child_init(unique_id_child_init, NULL, NULL, APR_HOOK_MIDDLE); - ap_hook_post_read_request(gen_unique_id, NULL, NULL, APR_HOOK_MIDDLE); -} - -module AP_MODULE_DECLARE_DATA unique_id_module = { - STANDARD20_MODULE_STUFF, - NULL, /* dir config creater */ - NULL, /* dir merger --- default is to override */ - NULL, /* server config */ - NULL, /* merge server configs */ - NULL, /* command apr_table_t */ - register_hooks /* register hooks */ -}; |