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239 lines
9.9 KiB
239 lines
9.9 KiB
--- trunk/modules/metadata/mod_unique_id.c 2011/12/02 23:02:04 1209766 |
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+++ trunk/modules/metadata/mod_unique_id.c 2013/07/10 16:20:31 1501827 |
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@@ -31,14 +31,11 @@ |
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#include "http_log.h" |
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#include "http_protocol.h" /* for ap_hook_post_read_request */ |
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-#if APR_HAVE_UNISTD_H |
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-#include <unistd.h> /* for getpid() */ |
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-#endif |
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+#define ROOT_SIZE 10 |
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typedef struct { |
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unsigned int stamp; |
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- unsigned int in_addr; |
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- unsigned int pid; |
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+ char root[ROOT_SIZE]; |
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unsigned short counter; |
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unsigned int thread_index; |
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} unique_id_rec; |
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@@ -64,20 +61,15 @@ |
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* gethostbyname (gethostname()) is unique across all the machines at the |
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* "site". |
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* |
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- * We also further assume that pids fit in 32-bits. If something uses more |
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- * than 32-bits, the fix is trivial, but it requires the unrolled uuencoding |
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- * loop to be extended. * A similar fix is needed to support multithreaded |
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- * servers, using a pid/tid combo. |
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- * |
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- * Together, the in_addr and pid are assumed to absolutely uniquely identify |
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- * this one child from all other currently running children on all servers |
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- * (including this physical server if it is running multiple httpds) from each |
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+ * The root is assumed to absolutely uniquely identify this one child |
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+ * from all other currently running children on all servers (including |
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+ * this physical server if it is running multiple httpds) from each |
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* other. |
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* |
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- * The stamp and counter are used to distinguish all hits for a particular |
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- * (in_addr,pid) pair. The stamp is updated using r->request_time, |
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- * saving cpu cycles. The counter is never reset, and is used to permit up to |
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- * 64k requests in a single second by a single child. |
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+ * The stamp and counter are used to distinguish all hits for a |
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+ * particular root. The stamp is updated using r->request_time, |
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+ * saving cpu cycles. The counter is never reset, and is used to |
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+ * permit up to 64k requests in a single second by a single child. |
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* |
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* The 144-bits of unique_id_rec are encoded using the alphabet |
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* [A-Za-z0-9@-], resulting in 24 bytes of printable characters. That is then |
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@@ -92,7 +84,7 @@ |
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* module change. |
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* |
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* It is highly desirable that identifiers exist for "eternity". But future |
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- * needs (such as much faster webservers, moving to 64-bit pids, or moving to a |
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+ * needs (such as much faster webservers, or moving to a |
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* multithreaded server) may dictate a need to change the contents of |
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* unique_id_rec. Such a future implementation should ensure that the first |
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* field is still a time_t stamp. By doing that, it is possible for a site to |
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@@ -100,7 +92,15 @@ |
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* wait one entire second, and then start all of their new-servers. This |
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* procedure will ensure that the new space of identifiers is completely unique |
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* from the old space. (Since the first four unencoded bytes always differ.) |
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+ * |
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+ * Note: previous implementations used 32-bits of IP address plus pid |
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+ * in place of the PRNG output in the "root" field. This was |
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+ * insufficient for IPv6-only hosts, required working DNS to determine |
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+ * a unique IP address (fragile), and needed a [0, 1) second sleep |
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+ * call at startup to avoid pid reuse. Use of the PRNG avoids all |
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+ * these issues. |
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*/ |
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+ |
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/* |
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* Sun Jun 7 05:43:49 CEST 1998 -- Alvaro |
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* More comments: |
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@@ -116,8 +116,6 @@ |
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* htonl/ntohl. Well, this shouldn't be a problem till year 2106. |
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*/ |
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-static unsigned global_in_addr; |
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- |
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/* |
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* XXX: We should have a per-thread counter and not use cur_unique_id.counter |
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* XXX: in all threads, because this is bad for performance on multi-processor |
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@@ -129,7 +127,7 @@ |
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/* |
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* Number of elements in the structure unique_id_rec. |
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*/ |
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-#define UNIQUE_ID_REC_MAX 5 |
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+#define UNIQUE_ID_REC_MAX 4 |
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static unsigned short unique_id_rec_offset[UNIQUE_ID_REC_MAX], |
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unique_id_rec_size[UNIQUE_ID_REC_MAX], |
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@@ -138,113 +136,32 @@ |
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static int unique_id_global_init(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *main_server) |
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{ |
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- char str[APRMAXHOSTLEN + 1]; |
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- apr_status_t rv; |
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- char *ipaddrstr; |
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- apr_sockaddr_t *sockaddr; |
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- |
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/* |
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* Calculate the sizes and offsets in cur_unique_id. |
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*/ |
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unique_id_rec_offset[0] = APR_OFFSETOF(unique_id_rec, stamp); |
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unique_id_rec_size[0] = sizeof(cur_unique_id.stamp); |
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- unique_id_rec_offset[1] = APR_OFFSETOF(unique_id_rec, in_addr); |
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- unique_id_rec_size[1] = sizeof(cur_unique_id.in_addr); |
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- unique_id_rec_offset[2] = APR_OFFSETOF(unique_id_rec, pid); |
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- unique_id_rec_size[2] = sizeof(cur_unique_id.pid); |
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- unique_id_rec_offset[3] = APR_OFFSETOF(unique_id_rec, counter); |
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- unique_id_rec_size[3] = sizeof(cur_unique_id.counter); |
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- unique_id_rec_offset[4] = APR_OFFSETOF(unique_id_rec, thread_index); |
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- unique_id_rec_size[4] = sizeof(cur_unique_id.thread_index); |
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+ unique_id_rec_offset[1] = APR_OFFSETOF(unique_id_rec, root); |
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+ unique_id_rec_size[1] = sizeof(cur_unique_id.root); |
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+ unique_id_rec_offset[2] = APR_OFFSETOF(unique_id_rec, counter); |
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+ unique_id_rec_size[2] = sizeof(cur_unique_id.counter); |
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+ unique_id_rec_offset[3] = APR_OFFSETOF(unique_id_rec, thread_index); |
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+ unique_id_rec_size[3] = sizeof(cur_unique_id.thread_index); |
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unique_id_rec_total_size = unique_id_rec_size[0] + unique_id_rec_size[1] + |
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- unique_id_rec_size[2] + unique_id_rec_size[3] + |
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- unique_id_rec_size[4]; |
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+ unique_id_rec_size[2] + unique_id_rec_size[3]; |
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/* |
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* Calculate the size of the structure when encoded. |
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*/ |
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unique_id_rec_size_uu = (unique_id_rec_total_size*8+5)/6; |
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- /* |
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- * Now get the global in_addr. Note that it is not sufficient to use one |
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- * of the addresses from the main_server, since those aren't as likely to |
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- * be unique as the physical address of the machine |
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- */ |
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- if ((rv = apr_gethostname(str, sizeof(str) - 1, p)) != APR_SUCCESS) { |
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- ap_log_error(APLOG_MARK, APLOG_ALERT, rv, main_server, APLOGNO(01563) |
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- "unable to find hostname of the server"); |
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- return HTTP_INTERNAL_SERVER_ERROR; |
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- } |
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- |
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- if ((rv = apr_sockaddr_info_get(&sockaddr, str, AF_INET, 0, 0, p)) == APR_SUCCESS) { |
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- global_in_addr = sockaddr->sa.sin.sin_addr.s_addr; |
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- } |
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- else { |
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- ap_log_error(APLOG_MARK, APLOG_ALERT, rv, main_server, APLOGNO(01564) |
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- "unable to find IPv4 address of \"%s\"", str); |
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-#if APR_HAVE_IPV6 |
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- if ((rv = apr_sockaddr_info_get(&sockaddr, str, AF_INET6, 0, 0, p)) == APR_SUCCESS) { |
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- memcpy(&global_in_addr, |
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- (char *)sockaddr->ipaddr_ptr + sockaddr->ipaddr_len - sizeof(global_in_addr), |
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- sizeof(global_in_addr)); |
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- ap_log_error(APLOG_MARK, APLOG_ALERT, rv, main_server, APLOGNO(01565) |
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- "using low-order bits of IPv6 address " |
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- "as if they were unique"); |
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- } |
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- else |
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-#endif |
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- return HTTP_INTERNAL_SERVER_ERROR; |
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- } |
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- |
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- apr_sockaddr_ip_get(&ipaddrstr, sockaddr); |
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- ap_log_error(APLOG_MARK, APLOG_INFO, 0, main_server, APLOGNO(01566) "using ip addr %s", |
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- ipaddrstr); |
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- |
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- /* |
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- * If the server is pummelled with restart requests we could possibly end |
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- * up in a situation where we're starting again during the same second |
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- * that has been used in previous identifiers. Avoid that situation. |
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- * |
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- * In truth, for this to actually happen not only would it have to restart |
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- * in the same second, but it would have to somehow get the same pids as |
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- * one of the other servers that was running in that second. Which would |
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- * mean a 64k wraparound on pids ... not very likely at all. |
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- * |
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- * But protecting against it is relatively cheap. We just sleep into the |
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- * next second. |
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- */ |
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- apr_sleep(apr_time_from_sec(1) - apr_time_usec(apr_time_now())); |
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return OK; |
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} |
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static void unique_id_child_init(apr_pool_t *p, server_rec *s) |
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{ |
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- pid_t pid; |
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- |
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- /* |
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- * Note that we use the pid because it's possible that on the same |
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- * physical machine there are multiple servers (i.e. using Listen). But |
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- * it's guaranteed that none of them will share the same pids between |
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- * children. |
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- * |
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- * XXX: for multithread this needs to use a pid/tid combo and probably |
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- * needs to be expanded to 32 bits |
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- */ |
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- pid = getpid(); |
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- cur_unique_id.pid = pid; |
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- |
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- /* |
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- * Test our assumption that the pid is 32-bits. It's possible that |
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- * 64-bit machines will declare pid_t to be 64 bits but only use 32 |
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- * of them. It would have been really nice to test this during |
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- * global_init ... but oh well. |
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- */ |
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- if ((pid_t)cur_unique_id.pid != pid) { |
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- ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(01567) |
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- "oh no! pids are greater than 32-bits! I'm broken!"); |
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- } |
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- |
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- cur_unique_id.in_addr = global_in_addr; |
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+ ap_random_insecure_bytes(&cur_unique_id.root, |
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+ sizeof(cur_unique_id.root)); |
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/* |
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* If we use 0 as the initial counter we have a little less protection |
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@@ -253,13 +170,6 @@ |
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*/ |
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ap_random_insecure_bytes(&cur_unique_id.counter, |
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sizeof(cur_unique_id.counter)); |
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- |
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- /* |
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- * We must always use network ordering for these bytes, so that |
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- * identifiers are comparable between machines of different byte |
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- * orderings. Note in_addr is already in network order. |
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- */ |
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- cur_unique_id.pid = htonl(cur_unique_id.pid); |
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} |
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/* NOTE: This is *NOT* the same encoding used by base64encode ... the last two |
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@@ -291,10 +201,8 @@ |
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unsigned short counter; |
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int i,j,k; |
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- new_unique_id.in_addr = cur_unique_id.in_addr; |
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- new_unique_id.pid = cur_unique_id.pid; |
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+ memcpy(&new_unique_id.root, &cur_unique_id.root, ROOT_SIZE); |
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new_unique_id.counter = cur_unique_id.counter; |
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- |
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new_unique_id.stamp = htonl((unsigned int)apr_time_sec(r->request_time)); |
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new_unique_id.thread_index = htonl((unsigned int)r->connection->id); |
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