add support for search domains to dns resolver

[musl] / src / network / lookup_name.c

diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index fb7b5c1..09734b5 100644 (file)
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -157,6 +157,46 @@ static int name_from_dns(struct address buf[static MAXADDRS], char canon[static
        return EAI_FAIL;
 }
 
+static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
+{
+       char search[256];
+       struct resolvconf conf;
+       size_t l, dots;
+       char *p, *z;
+
+       if (__get_resolv_conf(&conf, search, sizeof search) < 0) return -1;
+
+       /* Count dots, suppress search when >=ndots or name ends in
+        * a dot, which is an explicit request for global scope. */
+       for (dots=l=0; name[l]; l++) if (name[l]=='.') dots++;
+       if (dots >= conf.ndots || name[l-1]=='.') *search = 0;
+
+       /* This can never happen; the caller already checked length. */
+       if (l >= 256) return EAI_NONAME;
+
+       /* Name with search domain appended is setup in canon[]. This both
+        * provides the desired default canonical name (if the requested
+        * name is not a CNAME record) and serves as a buffer for passing
+        * the full requested name to name_from_dns. */
+       memcpy(canon, name, l);
+       canon[l] = '.';
+
+       for (p=search; *p; p=z) {
+               for (; isspace(*p); p++);
+               for (z=p; *z && !isspace(*z); z++);
+               if (z==p) break;
+               if (z-p < 256 - l - 1) {
+                       memcpy(canon+l+1, p, z-p);
+                       canon[z-p+1+l] = 0;
+                       int cnt = name_from_dns(buf, canon, canon, family);
+                       if (cnt) return cnt;
+               }
+       }
+
+       canon[l] = 0;
+       return name_from_dns(buf, canon, name, family);
+}
+
 static const struct policy {
        unsigned char addr[16];
        unsigned char len, mask;
@@ -257,7 +297,7 @@ int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], c
        if (!cnt) cnt = name_from_numeric(buf, name, family);
        if (!cnt && !(flags & AI_NUMERICHOST)) {
                cnt = name_from_hosts(buf, canon, name, family);
-               if (!cnt) cnt = name_from_dns(buf, canon, name, family);
+               if (!cnt) cnt = name_from_dns_search(buf, canon, name, family);
        }
        if (cnt<=0) return cnt ? cnt : EAI_NONAME;