From 64533ee069c306bd9caf642fe218e9137a3b1572 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Thu, 2 Dec 2010 10:25:58 +0000 Subject: [PATCH] gresolv: Add scope handling to RFC3484 sort --- gweb/gresolv.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-) diff --git a/gweb/gresolv.c b/gweb/gresolv.c index a5fc152..ed1ccab 100644 --- a/gweb/gresolv.c +++ b/gweb/gresolv.c @@ -39,7 +39,8 @@ struct sort_result { int precedence; - int scope; + int src_scope; + int dst_scope; int src_label; int dst_label; gboolean reachable; @@ -832,6 +833,49 @@ static int match_gai_table(struct sockaddr *sa, const struct gai_table *tbl) } } +#define DQUAD(_a,_b,_c,_d) ( ((_a)<<24) | ((_b)<<16) | ((_c)<<8) | (_d) ) +#define V4MATCH(addr, a,b,c,d, m) ( ((addr) ^ DQUAD(a,b,c,d)) >> (32 - (m)) ) + +#define RFC3484_SCOPE_LINK 2 +#define RFC3484_SCOPE_SITE 5 +#define RFC3484_SCOPE_GLOBAL 14 + +static int addr_scope(struct sockaddr *sa) +{ + if (sa->sa_family == AF_INET) { + struct sockaddr_in *sin = (void *)sa; + guint32 addr = ntohl(sin->sin_addr.s_addr); + + if (V4MATCH(addr, 169,254,0,0, 16) || + V4MATCH(addr, 127,0,0,0, 8)) + return RFC3484_SCOPE_LINK; + + /* Site-local */ + if (V4MATCH(addr, 10,0,0,0, 8) || + V4MATCH(addr, 172,16,0,0, 12) || + V4MATCH(addr, 192,168,0,0, 16)) + return RFC3484_SCOPE_SITE; + + /* Global */ + return RFC3484_SCOPE_GLOBAL; + } else { + struct sockaddr_in6 *sin6 = (void *)sa; + + /* Multicast addresses have a 4-bit scope field */ + if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr)) + return sin6->sin6_addr.s6_addr[1] & 0xf; + + if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) || + IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr)) + return RFC3484_SCOPE_LINK; + + if (IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr)) + return RFC3484_SCOPE_SITE; + + return RFC3484_SCOPE_GLOBAL; + } +} + static int rfc3484_compare(const void *__one, const void *__two) { const struct sort_result *one = __one; @@ -844,6 +888,12 @@ static int rfc3484_compare(const void *__one, const void *__two) return 1; /* Rule 2: Prefer matching scope */ + if (one->dst_scope == one->src_scope && + two->dst_scope != two->src_scope) + return -1; + else if (two->dst_scope == two->src_scope && + one->dst_scope != one->src_scope) + return 1; /* Rule 3: Avoid deprecated addresses */ @@ -866,6 +916,8 @@ static int rfc3484_compare(const void *__one, const void *__two) /* Rule 7: Prefer native transport */ /* Rule 8: Prefer smaller scope */ + if (one->dst_scope != two->dst_scope) + return one->dst_scope - two->dst_scope; /* Rule 9: Use longest matching prefix */ @@ -886,6 +938,8 @@ static void rfc3484_sort_results(struct resolv_lookup *lookup) res->precedence = match_gai_table(&res->dst.sa, gai_precedences); res->dst_label = match_gai_table(&res->dst.sa, gai_labels); res->src_label = match_gai_table(&res->src.sa, gai_labels); + res->dst_scope = addr_scope(&res->dst.sa); + res->src_scope = addr_scope(&res->src.sa); } qsort(lookup->results, lookup->nr_results, sizeof(struct sort_result), -- 2.7.4