Date: Sat, 19 Jun 2021 20:28:26 GMT From: Lutz Donnerhacke <donner@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: d261e57deacb - main - libalias: Switch to efficient data structure for incoming traffic Message-ID: <202106192028.15JKSQFm081263@gitrepo.freebsd.org>
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The branch main has been updated by donner: URL: https://cgit.FreeBSD.org/src/commit/?id=d261e57deacb0d00d9e827447f235df83dda3e3a commit d261e57deacb0d00d9e827447f235df83dda3e3a Author: Lutz Donnerhacke <donner@FreeBSD.org> AuthorDate: 2021-05-28 20:36:59 +0000 Commit: Lutz Donnerhacke <donner@FreeBSD.org> CommitDate: 2021-06-19 20:12:28 +0000 libalias: Switch to efficient data structure for incoming traffic Current data structure is using a hash of unordered lists. Those unordered lists are quite efficient, because the least recently inserted entries are most likely to be used again. In order to avoid long search times in other cases, the lists are hashed into many buckets. Unfortunatly a search for a miss needs an exhaustive inspection and a careful definition of the hash. Splay trees offer a similar feature: Almost O(1) for access of the least recently used entries, and amortized O(ln(n)) for almost all other cases. Get rid of the hash. Now the data structure should able to quickly react to external packets without eating CPU cycles for breakfast, preventing a DoS. PR: 192888 Discussed with: Dimitry Luhtionov MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D30536 --- sys/netinet/libalias/alias_db.c | 75 +++++++++++++++++--------------------- sys/netinet/libalias/alias_local.h | 6 +-- 2 files changed, 36 insertions(+), 45 deletions(-) diff --git a/sys/netinet/libalias/alias_db.c b/sys/netinet/libalias/alias_db.c index a5a21e40d0cf..53ad3396d66b 100644 --- a/sys/netinet/libalias/alias_db.c +++ b/sys/netinet/libalias/alias_db.c @@ -424,43 +424,39 @@ cmp_out(struct alias_link *a, struct alias_link *b) { SPLAY_PROTOTYPE(splay_out, alias_link, all.out, cmp_out); SPLAY_GENERATE(splay_out, alias_link, all.out, cmp_out); -#define INGUARD \ - if (grp->alias_port != alias_port || \ - grp->link_type != link_type || \ - grp->alias_addr.s_addr != alias_addr.s_addr) \ - continue; +static inline int +cmp_in(struct group_in *a, struct group_in *b) { + int i = a->alias_port - b->alias_port; + if (i != 0) return (i); + i = a->link_type - b->link_type; + if (i != 0) return (i); + i = a->alias_addr.s_addr - b->alias_addr.s_addr; + return (i); +} +SPLAY_PROTOTYPE(splay_in, group_in, in, cmp_in); +SPLAY_GENERATE(splay_in, group_in, in, cmp_in); static struct group_in * StartPointIn(struct libalias *la, struct in_addr alias_addr, u_short alias_port, int link_type, int create) { - u_int n; - struct group_in *grp, *tmp; - - n = alias_addr.s_addr; - n += alias_port; - n += link_type; - n %= LINK_TABLE_IN_SIZE; + struct group_in *grp; + struct group_in needle = { + .alias_addr = alias_addr, + .alias_port = alias_port, + .link_type = link_type + }; - LIST_FOREACH_SAFE(grp, &la->groupTableIn[n], group_in, tmp) { - /* Auto cleanup */ - if (LIST_EMPTY(&grp->full) && LIST_EMPTY(&grp->partial)) { - LIST_REMOVE(grp, group_in); - free(grp); - } else { - INGUARD; - return (grp); - } - } - if (!create || (grp = malloc(sizeof(*grp))) == NULL) + grp = SPLAY_FIND(splay_in, &la->linkSplayIn, &needle); + if (grp != NULL || !create || (grp = malloc(sizeof(*grp))) == NULL) return (grp); grp->alias_addr = alias_addr; grp->alias_port = alias_port; grp->link_type = link_type; LIST_INIT(&grp->full); LIST_INIT(&grp->partial); - LIST_INSERT_HEAD(&la->groupTableIn[n], grp, group_in); + SPLAY_INSERT(splay_in, &la->linkSplayIn, grp); return (grp); } #undef INGUARD @@ -815,25 +811,13 @@ static void CleanupAliasData(struct libalias *la, int deletePermanent) { struct alias_link *lnk, *lnk_tmp; - u_int i; LIBALIAS_LOCK_ASSERT(la); /* permanent entries may stay */ TAILQ_FOREACH_SAFE(lnk, &la->checkExpire, expire.list, lnk_tmp) DeleteLink(&lnk, deletePermanent); - - for (i = 0; i < LINK_TABLE_IN_SIZE; i++) { - struct group_in *grp, *grp_tmp; - - LIST_FOREACH_SAFE(grp, &la->groupTableIn[i], group_in, grp_tmp) - if (LIST_EMPTY(&grp->full) && LIST_EMPTY(&grp->partial)) { - LIST_REMOVE(grp, group_in); - free(grp); - } - } } - static void CleanupLink(struct libalias *la, struct alias_link **lnk, int deletePermanent) { @@ -882,7 +866,9 @@ DeleteLink(struct alias_link **plnk, int deletePermanent) case LINK_PPTP: LIST_REMOVE(lnk, pptp.list); break; - default: + default: { + struct group_in *grp; + /* Free memory allocated for LSNAT server pool */ if (lnk->server != NULL) { struct server *head, *curr, *next; @@ -899,6 +885,16 @@ DeleteLink(struct alias_link **plnk, int deletePermanent) /* Adjust input table pointers */ LIST_REMOVE(lnk, all.in); + + /* Remove intermediate node, if empty */ + grp = StartPointIn(la, lnk->alias_addr, lnk->alias_port, lnk->link_type, 0); + if (grp != NULL && + LIST_EMPTY(&grp->full) && + LIST_EMPTY(&grp->partial)) { + SPLAY_REMOVE(splay_in, &la->linkSplayIn, grp); + free(grp); + } + } break; } @@ -2465,8 +2461,6 @@ finishoff(void) struct libalias * LibAliasInit(struct libalias *la) { - int i; - if (la == NULL) { #ifdef _KERNEL #undef malloc /* XXX: ugly */ @@ -2490,9 +2484,8 @@ LibAliasInit(struct libalias *la) LibAliasTime = time(NULL); #endif + SPLAY_INIT(&la->linkSplayIn); SPLAY_INIT(&la->linkSplayOut); - for (i = 0; i < LINK_TABLE_IN_SIZE; i++) - LIST_INIT(&la->groupTableIn[i]); LIST_INIT(&la->pptpList); TAILQ_INIT(&la->checkExpire); #ifdef _KERNEL diff --git a/sys/netinet/libalias/alias_local.h b/sys/netinet/libalias/alias_local.h index a1ad08a979d2..938744924dcc 100644 --- a/sys/netinet/libalias/alias_local.h +++ b/sys/netinet/libalias/alias_local.h @@ -67,8 +67,6 @@ #endif /* Sizes of input and output link tables */ -#define LINK_TABLE_IN_SIZE 4001 - #define GET_ALIAS_PORT -1 #define GET_ALIAS_ID GET_ALIAS_PORT @@ -84,7 +82,7 @@ struct group_in { struct in_addr alias_addr; u_short alias_port; int link_type; - LIST_ENTRY(group_in) group_in; + SPLAY_ENTRY(group_in) in; LIST_HEAD(, alias_link) full, partial; }; @@ -101,7 +99,7 @@ struct libalias { * Each link record is doubly indexed into input and * output lookup tables. */ SPLAY_HEAD(splay_out, alias_link) linkSplayOut; - LIST_HEAD (, group_in) groupTableIn[LINK_TABLE_IN_SIZE]; + SPLAY_HEAD(splay_in, group_in) linkSplayIn; LIST_HEAD (, alias_link) pptpList; /* HouseKeeping */ TAILQ_HEAD (, alias_link) checkExpire;
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