reuse parsed resolv.conf in dns core to avoid re-reading/re-parsing

[musl] / src / network / lookup_name.c

diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index 0225a93..a26ad53 100644 (file)
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -9,6 +9,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <errno.h>
 #include "lookup.h"
 #include "stdio_impl.h"
 #include "syscall.h"
@@ -51,7 +52,14 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
        int cnt = 0;
        unsigned char _buf[1032];
        FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
-       if (!f) return 0;
+       if (!f) switch (errno) {
+       case ENOENT:
+       case ENOTDIR:
+       case EACCES:
+               return 0;
+       default:
+               return EAI_SYSTEM;
+       }
        while (fgets(line, sizeof line, f) && cnt < MAXADDRS) {
                char *p, *z;
 
@@ -85,7 +93,7 @@ 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
@@ -117,7 +125,7 @@ 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] };
@@ -137,17 +145,59 @@ static int name_from_dns(struct address buf[static MAXADDRS], char canon[static
                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);
 
        if (ctx.cnt) return ctx.cnt;
        if (alens[0] < 4 || (abuf[0][3] & 15) == 2) return EAI_AGAIN;
-       if ((abuf[0][3] & 15) == 3) return EAI_NONAME;
+       if ((abuf[0][3] & 15) == 0) return EAI_NONAME;
+       if ((abuf[0][3] & 15) == 3) return 0;
        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;
@@ -248,7 +298,7 @@ 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;