From 0d55e9c536779215a7e49b220041fdacde25d74a Mon Sep 17 00:00:00 2001 From: Gerald Carter Date: Fri, 6 Jun 2003 14:11:14 +0000 Subject: merge from APP_HEAD. Push negative connection cache into rpc_find_dc(). Should probably be extended some more in 3.0 but this is what we have for the moment. (This used to be commit 0e23abf95cf7ba2d0a314a34bddb4d46de2a3cd1) --- source3/libsmb/namequery_dc.c | 155 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 148 insertions(+), 7 deletions(-) (limited to 'source3/libsmb/namequery_dc.c') diff --git a/source3/libsmb/namequery_dc.c b/source3/libsmb/namequery_dc.c index ffc64139e9..e98b728963 100644 --- a/source3/libsmb/namequery_dc.c +++ b/source3/libsmb/namequery_dc.c @@ -25,15 +25,149 @@ #include "includes.h" -/* - find the DC for a domain using methods appropriate for a RPC domain -*/ +#define FAILED_CONNECTION_CACHE_TIMEOUT 30 /* Seconds between attempts */ + +struct failed_connection_cache { + fstring domain_name; + fstring controller; + time_t lookup_time; + NTSTATUS nt_status; + struct failed_connection_cache *prev, *next; +}; + +static struct failed_connection_cache *failed_connection_cache; + +/********************************************************************** + Check for a previously failed connection +**********************************************************************/ + +static NTSTATUS check_negative_conn_cache( const char *domain, const char *server ) +{ + struct failed_connection_cache *fcc; + NTSTATUS result = NT_STATUS_UNSUCCESSFUL; + + /* can't check if we don't have strings */ + + if ( !domain || !server ) + return NT_STATUS_OK; + + for (fcc = failed_connection_cache; fcc; fcc = fcc->next) { + + /* + * we have a match IFF the domain and server name matches + * (a) the domain matches, + * (b) the IP address matches (if we have one) + * (c) the server name (if specified) matches + */ + + if ( !strequal(domain, fcc->domain_name) || !strequal(server, fcc->controller) ) + continue; /* no match; check the next entry */ + + /* we have a match so see if it is still current */ + + if ((time(NULL) - fcc->lookup_time) > FAILED_CONNECTION_CACHE_TIMEOUT) + { + /* Cache entry has expired, delete it */ + + DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n", + domain, server )); + + DLIST_REMOVE(failed_connection_cache, fcc); + SAFE_FREE(fcc); + + return NT_STATUS_OK; + } + + /* The timeout hasn't expired yet so return false */ + + DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n", + domain, server )); + + result = fcc->nt_status; + return result; + } + + /* end of function means no cache entry */ + return NT_STATUS_OK; +} + +/********************************************************************** + Add an entry to the failed conneciton cache +**********************************************************************/ + +void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result) +{ + struct failed_connection_cache *fcc; + + SMB_ASSERT(!NT_STATUS_IS_OK(result)); + + /* Check we already aren't in the cache. We always have to have + a domain, but maybe not a specific DC name. */ + + for (fcc = failed_connection_cache; fcc; fcc = fcc->next) { + if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) ) + { + DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n", + domain, server )); + return; + } + } + + /* Create negative lookup cache entry for this domain and controller */ + + if ( !(fcc = (struct failed_connection_cache *)malloc(sizeof(struct failed_connection_cache))) ) + { + DEBUG(0, ("malloc failed in add_failed_connection_entry!\n")); + return; + } + + ZERO_STRUCTP(fcc); + + fstrcpy( fcc->domain_name, domain ); + fstrcpy( fcc->controller, server ); + fcc->lookup_time = time(NULL); + fcc->nt_status = result; + + DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n", + domain, server )); + + DLIST_ADD(failed_connection_cache, fcc); +} + +/**************************************************************************** +****************************************************************************/ + +void flush_negative_conn_cache( void ) +{ + struct failed_connection_cache *fcc; + + fcc = failed_connection_cache; + + while (fcc) { + struct failed_connection_cache *fcc_next; + + fcc_next = fcc->next; + DLIST_REMOVE(failed_connection_cache, fcc); + free(fcc); + + fcc = fcc_next; + } + +} + +/**************************************************************************** + Utility function to return the name of a DC using RPC. The name is + guaranteed to be valid since we have already done a name_status_find on it + and we have checked our negative connection cache + ***************************************************************************/ + BOOL rpc_find_dc(const char *domain, fstring srv_name, struct in_addr *ip_out) { struct in_addr *ip_list = NULL, dc_ip, exclude_ip; int count, i; BOOL list_ordered; BOOL use_pdc_only; + NTSTATUS result; zero_ip(&exclude_ip); @@ -41,11 +175,15 @@ BOOL rpc_find_dc(const char *domain, fstring srv_name, struct in_addr *ip_out) /* Lookup domain controller name */ - if ( use_pdc_only && get_pdc_ip(domain, &dc_ip) ) { + if ( use_pdc_only && get_pdc_ip(domain, &dc_ip) ) + { DEBUG(10,("rpc_find_dc: Atempting to lookup PDC to avoid sam sync delays\n")); if (name_status_find(domain, 0x1c, 0x20, dc_ip, srv_name)) { - goto done; + /* makre we we haven't tried this on previously and failed */ + result = check_negative_conn_cache( domain, srv_name ); + if ( NT_STATUS_IS_OK(result) ) + goto done; } /* Didn't get name, remember not to talk to this DC. */ exclude_ip = dc_ip; @@ -77,8 +215,11 @@ BOOL rpc_find_dc(const char *domain, fstring srv_name, struct in_addr *ip_out) continue; if (name_status_find(domain, 0x1c, 0x20, ip_list[i], srv_name)) { - dc_ip = ip_list[i]; - goto done; + result = check_negative_conn_cache( domain, srv_name ); + if ( NT_STATUS_IS_OK(result) ) { + dc_ip = ip_list[i]; + goto done; + } } } -- cgit