Simplify getnameinfo (#196)

The getnameinfo implementation requires an address -> name lookup on the
hosts file (ie struct HostsTxt) and the previous implementation used
flags to check whether HostsTxt was sorted according to address or name,
and then re-sorted it if necessary. Now getnameinfo lookup does not
require sorting, it does a simple linear lookup, and so the related code
was simplified

See #172 for discussion.

libc/dns/gethoststxt.c

@@ -61,7 +61,6 @@ const struct HostsTxt *GetHostsTxt(void) {
   init = &g_hoststxt_init;
   if (!g_hoststxt) {
     g_hoststxt = &init->ht;
-    init->ht.sorted_by = HOSTSTXT_NOT_SORTED;
     init->ht.entries.n = pushpop(ARRAYLEN(init->entries));
     init->ht.entries.p = init->entries;
     init->ht.strings.n = pushpop(ARRAYLEN(init->strings));
@@ -75,7 +74,7 @@ const struct HostsTxt *GetHostsTxt(void) {
       /* TODO(jart): Elevate robustness. */
     }
     fclose(f);
-    SortHostsTxt(g_hoststxt, HOSTSTXT_SORTEDBYNAME);
+    SortHostsTxt(g_hoststxt);
   }
   return g_hoststxt;
 }

libc/dns/hoststxt.h

@@ -21,12 +21,7 @@ struct HostsTxtStrings {
   char *p;
 };
 
-#define HOSTSTXT_NOT_SORTED   0
-#define HOSTSTXT_SORTEDBYNAME 1
-#define HOSTSTXT_SORTEDBYADDR 2
-
 struct HostsTxt {
-  int sorted_by;
   struct HostsTxtEntries entries;
   struct HostsTxtStrings strings;
 };
@@ -34,12 +29,12 @@ struct HostsTxt {
 const struct HostsTxt *GetHostsTxt(void) returnsnonnull;
 void FreeHostsTxt(struct HostsTxt **) paramsnonnull();
 int ParseHostsTxt(struct HostsTxt *, FILE *) paramsnonnull();
-void SortHostsTxt(struct HostsTxt *, int) paramsnonnull();
+void SortHostsTxt(struct HostsTxt *) paramsnonnull();
 int ResolveHostsTxt(const struct HostsTxt *, int, const char *,
                     struct sockaddr *, uint32_t, const char **)
     paramsnonnull((1, 3));
 int ResolveHostsReverse(const struct HostsTxt *, int, const uint8_t *, char *,
-                        size_t);
+                        size_t) paramsnonnull((1, 3));
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/dns/resolvehostsreverse.c

@@ -8,11 +8,6 @@
 #include "libc/sysv/consts/af.h"
 #include "libc/sysv/errfuns.h"
 
-static int hoststxtcmpaddr(const uint8_t *ip1, const struct HostsTxtEntry *he2) {
-  uint32_t v1 = *((uint32_t *)ip1), v2 = *((uint32_t *)he2->ip);
-  return (v1 == v2 ? 0 : (v1 > v2 ? 1 : -1));
-}
-
 /**
  * Finds name associated with address in HOSTS.TXT table.
  *
@@ -27,15 +22,21 @@ static int hoststxtcmpaddr(const uint8_t *ip1, const struct HostsTxtEntry *he2)
  */
 int ResolveHostsReverse(const struct HostsTxt *ht, int af, const uint8_t *ip,
                         char *buf, size_t bufsize) {
-  struct HostsTxtEntry *entry;
+  struct HostsTxtEntry *entry = NULL;
+  uint32_t v1, v2;
+
   if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
-  if (!ht->entries.p) return -1;
+  if (!ht->entries.p || !buf || bufsize == 0) return -1;
 
-  if (ht->sorted_by != HOSTSTXT_SORTEDBYADDR)
+  v1 = *((uint32_t *)ip);
-    SortHostsTxt(ht, HOSTSTXT_SORTEDBYADDR);
+  for (size_t j = 0; j < ht->entries.i; j++) {
+    v2 = *((uint32_t *)ht->entries.p[j].ip);
+    if (v1 == v2) {
+      entry = &(ht->entries.p[j]);
+      break;
+    }
+  }
 
-  entry = bsearch(ip, ht->entries.p, ht->entries.i,
-                  sizeof(struct HostsTxtEntry), (void *)hoststxtcmpaddr);
   if (entry) {
     strncpy(buf, &ht->strings.p[entry->name], bufsize);
     return 1;

libc/dns/resolvehoststxt.c

@@ -52,8 +52,6 @@ int ResolveHostsTxt(const struct HostsTxt *ht, int af, const char *name,
   struct sockaddr_in *addr4;
   struct HostsTxtEntry *entry;
   if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
-  if (ht->sorted_by != HOSTSTXT_SORTEDBYNAME)
-    SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
   if ((entry = bsearch_r(name, ht->entries.p, ht->entries.i,
                          sizeof(struct HostsTxtEntry), (void *)hoststxtgetcmp,
                          ht->strings.p))) {

libc/dns/sorthoststxt.c

@@ -30,17 +30,6 @@ static int cmphoststxt(const struct HostsTxtEntry *e1,
   return CompareDnsNames(&strings[e1->name], &strings[e2->name]);
 }
 
-/**
- * Compares addresses in HOSTS.TXT table.
- * @see ResolveHostsReverse()
- */
-static int cmphostsaddr(const struct HostsTxtEntry *e1,
-                        const struct HostsTxtEntry *e2) {
-  if (e1 == e2) return 0;
-  uint32_t v1 = *((uint32_t *)e1->ip), v2 = *((uint32_t *)e2->ip);
-  return (v1 == v2 ? 0 : (v1 > v2 ? 1 : -1));
-}
-
 /**
  * Sorts entries in HOSTS.TXT table.
  *
@@ -52,16 +41,9 @@ static int cmphostsaddr(const struct HostsTxtEntry *e1,
  * possible to efficiently search for subdomains, once the initial sort
  * is done.
  */
-void SortHostsTxt(struct HostsTxt *ht, int sort_by) {
+void SortHostsTxt(struct HostsTxt *ht) {
   if (ht->entries.p) {
-    if (sort_by == HOSTSTXT_SORTEDBYNAME) {
+    qsort_r(ht->entries.p, ht->entries.i, sizeof(*ht->entries.p),
-      qsort_r(ht->entries.p, ht->entries.i, sizeof(*ht->entries.p),
+            (void *)cmphoststxt, ht->strings.p);
-              (void *)cmphoststxt, ht->strings.p);
-      ht->sorted_by = HOSTSTXT_SORTEDBYNAME;
-    } else {
-      qsort(ht->entries.p, ht->entries.i, sizeof(*ht->entries.p),
-            (void *)cmphostsaddr);
-      ht->sorted_by = HOSTSTXT_SORTEDBYADDR;
-    }
   }
 }

test/libc/dns/parsehoststxt_test.c

@@ -48,7 +48,7 @@ TEST(ParseHostsTxt, testCorrectlyTokenizesAndSorts) {
   ASSERT_EQ(1, fwrite(kInput, strlen(kInput), 1, f));
   rewind(f);
   ASSERT_EQ(0, ParseHostsTxt(ht, f));
-  SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
+  SortHostsTxt(ht);
   ASSERT_EQ(4, ht->entries.i);
   EXPECT_STREQ("cat.example.", &ht->strings.p[ht->entries.p[0].name]);
   EXPECT_STREQ("cat.example.", &ht->strings.p[ht->entries.p[0].canon]);

test/libc/dns/resolvehoststxt_test.c

@@ -49,7 +49,7 @@ TEST(ResolveHostsTxt, testBasicLookups) {
   struct HostsTxt *ht = calloc(1, sizeof(struct HostsTxt));
   FILE *f = fmemopen(kInput, strlen(kInput), "r+");
   ASSERT_EQ(0, ParseHostsTxt(ht, f));
-  SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
+  SortHostsTxt(ht);
   ASSERT_EQ(5, ht->entries.i);
   EXPECT_STREQ("127.0.0.1", EzIp4Lookup(ht, "localhost"));
   EXPECT_STREQ("203.0.113.1", EzIp4Lookup(ht, "lol"));
@@ -66,7 +66,7 @@ TEST(ResolveHostsTxt, testCanonicalize) {
   struct HostsTxt *ht = calloc(1, sizeof(struct HostsTxt));
   FILE *f = fmemopen(kInput, strlen(kInput), "r+");
   ASSERT_EQ(0, ParseHostsTxt(ht, f));
-  SortHostsTxt(ht, HOSTSTXT_SORTEDBYNAME);
+  SortHostsTxt(ht);
   ASSERT_EQ(5, ht->entries.i);
   EXPECT_STREQ("localhost", EzCanonicalize(ht, "localhost"));
   EXPECT_STREQ("lol.example.", EzCanonicalize(ht, "lol"));