accept trailing . and empty domain names

trailing . should be accepted in domain name strings by convention
(RFC 1034), host name lookup accepts "." but rejects empty "", res_*
interfaces also accept empty name following existing practice.

diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index 68b172b..743aa08 100644 (file)
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -14,7 +14,7 @@
 static int is_valid_hostname(const char *host)
 {
        const unsigned char *s;
-       if (strnlen(host, 254)-1 >= 253 || mbstowcs(0, host, 0) == -1) return 0;
+       if (strnlen(host, 255)-1 >= 254 || mbstowcs(0, host, 0) == -1) return 0;
        for (s=(void *)host; *s>=0x80 || *s=='.' || *s=='-' || isalnum(*s); s++);
        return !*s;
 }
@@ -152,8 +152,9 @@ int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], c
 
        *canon = 0;
        if (name) {
-               size_t l;
-               if ((l = strnlen(name, 254))-1 >= 253)
+               /* reject empty name and check len so it fits into temp bufs */
+               size_t l = strnlen(name, 255);
+               if (l-1 >= 254)
                        return EAI_NONAME;
                memcpy(canon, name, l+1);
        }

diff --git a/src/network/res_mkquery.c b/src/network/res_mkquery.c
index 7c49709..ec4568a 100644 (file)
--- a/src/network/res_mkquery.c
+++ b/src/network/res_mkquery.c
@@ -10,13 +10,16 @@ int __res_mkquery(int op, const char *dname, int class, int type,
        int id, i, j;
        unsigned char q[280];
        struct timespec ts;
-       size_t l = strnlen(dname, 254);
+       size_t l = strnlen(dname, 255);
+       int n;
 
-       if (l-1>=253 || buflen<18+l || op>15u || class>255u || type>255u)
+       if (l && dname[l-1]=='.') l--;
+       n = 17+l+!!l;
+       if (l>253 || buflen<n || op>15u || class>255u || type>255u)
                return -1;
 
        /* Construct query template - ID will be filled later */
-       memset(q, 0, 18+l);
+       memset(q, 0, n);
        q[2] = op*8 + 1;
        q[5] = 1;
        memcpy((char *)q+13, dname, l);
@@ -34,8 +37,8 @@ int __res_mkquery(int op, const char *dname, int class, int type,
        q[0] = id/256;
        q[1] = id;
 
-       memcpy(buf, q, 18+l);
-       return 18+l;
+       memcpy(buf, q, n);
+       return n;
 }
 
 weak_alias(__res_mkquery, res_mkquery);

diff --git a/src/network/res_querydomain.c b/src/network/res_querydomain.c
index 8ba31f4..727e6f6 100644 (file)
--- a/src/network/res_querydomain.c
+++ b/src/network/res_querydomain.c
@@ -3,10 +3,10 @@
 
 int res_querydomain(const char *name, const char *domain, int class, int type, unsigned char *dest, int len)
 {
-       char tmp[254];
-       size_t nl = strnlen(name, 254);
-       size_t dl = strnlen(domain, 254);
-       if (nl+dl+1 > 253) return -1;
+       char tmp[255];
+       size_t nl = strnlen(name, 255);
+       size_t dl = strnlen(domain, 255);
+       if (nl+dl+1 > 254) return -1;
        memcpy(tmp, name, nl);
        tmp[nl] = '.';
        memcpy(tmp+nl+1, domain, dl+1);