in performing dns lookups, check result from res_mkquery

[musl] / src / network / lookup_name.c

diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index fb7b5c1..d3d97b4 100644 (file)
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -49,7 +49,7 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
 {
        char line[512];
        size_t l = strlen(name);
-       int cnt = 0;
+       int cnt = 0, badfam = 0;
        unsigned char _buf[1032];
        FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
        if (!f) switch (errno) {
@@ -71,8 +71,16 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
                /* Isolate IP address to parse */
                for (p=line; *p && !isspace(*p); p++);
                *p++ = 0;
-               if (name_from_numeric(buf+cnt, line, family))
+               switch (name_from_numeric(buf+cnt, line, family)) {
+               case 1:
                        cnt++;
+                       break;
+               case 0:
+                       continue;
+               default:
+                       badfam = EAI_NONAME;
+                       continue;
+               }
 
                /* Extract first name as canonical name */
                for (; *p && isspace(*p); p++);
@@ -81,7 +89,7 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
                if (is_valid_hostname(p)) memcpy(canon, p, z-p+1);
        }
        __fclose_ca(f);
-       return cnt;
+       return cnt ? cnt : badfam;
 }
 
 struct dpc_ctx {
@@ -93,7 +101,7 @@ struct dpc_ctx {
 int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *), void *);
 int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
 int __res_mkquery(int, const char *, int, int, const unsigned char *, int, const unsigned char*, unsigned char *, int);
-int __res_msend(int, const unsigned char *const *, const int *, unsigned char *const *, int *, int);
+int __res_msend_rc(int, const unsigned char *const *, const int *, unsigned char *const *, int *, int, const struct resolvconf *);
 
 #define RR_A 1
 #define RR_CNAME 5
@@ -125,7 +133,7 @@ static int dns_parse_callback(void *c, int rr, const void *data, int len, const
        return 0;
 }
 
-static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
+static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, const struct resolvconf *conf)
 {
        unsigned char qbuf[2][280], abuf[2][512];
        const unsigned char *qp[2] = { qbuf[0], qbuf[1] };
@@ -137,15 +145,20 @@ static int name_from_dns(struct address buf[static MAXADDRS], char canon[static
        if (family != AF_INET6) {
                qlens[nq] = __res_mkquery(0, name, 1, RR_A, 0, 0, 0,
                        qbuf[nq], sizeof *qbuf);
+               if (qlens[nq] == -1)
+                       return EAI_NONAME;
                nq++;
        }
        if (family != AF_INET) {
                qlens[nq] = __res_mkquery(0, name, 1, RR_AAAA, 0, 0, 0,
                        qbuf[nq], sizeof *qbuf);
+               if (qlens[nq] == -1)
+                       return EAI_NONAME;
                nq++;
        }
 
-       if (__res_msend(nq, qp, qlens, ap, alens, sizeof *abuf) < 0) return EAI_SYSTEM;
+       if (__res_msend_rc(nq, qp, qlens, ap, alens, sizeof *abuf, conf) < 0)
+               return EAI_SYSTEM;
 
        for (i=0; i<nq; i++)
                __dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
@@ -157,6 +170,46 @@ 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, &conf);
+                       if (cnt) return cnt;
+               }
+       }
+
+       canon[l] = 0;
+       return name_from_dns(buf, canon, name, family, &conf);
+}
+
 static const struct policy {
        unsigned char addr[16];
        unsigned char len, mask;
@@ -257,7 +310,7 @@ 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;