resolve: split sub-functions out of tor_addr_lookup()

And remove the practracker exception for tor_addr_lookup().

Cleanup after 30721.

scripts/maint/practracker/exceptions.txt

@@ -272,7 +272,6 @@ problem function-size /src/lib/math/prob_distr.c:sample_uniform_interval() 145
 problem function-size /src/lib/net/address.c:tor_addr_parse_mask_ports() 198
 problem function-size /src/lib/net/address.c:tor_addr_compare_masked() 111
 problem function-size /src/lib/net/inaddr.c:tor_inet_pton() 107
-problem function-size /src/lib/net/resolve.c:tor_addr_lookup() 110
 problem function-size /src/lib/net/socketpair.c:tor_ersatz_socketpair() 102
 problem function-size /src/lib/osinfo/uname.c:get_uname() 116
 problem function-size /src/lib/process/process_unix.c:process_unix_exec() 220

src/lib/net/resolve.c

@@ -58,51 +58,18 @@ tor_lookup_hostname,(const char *name, uint32_t *addr))
   return -1;
 }
 
-/** Similar behavior to Unix gethostbyname: resolve <b>name</b>, and set
- * *<b>addr</b> to the proper IP address and family. The <b>family</b>
- * argument (which must be AF_INET, AF_INET6, or AF_UNSPEC) declares a
- * <i>preferred</i> family, though another one may be returned if only one
- * family is implemented for this address.
- *
- * Like tor_addr_parse(), this function accepts IPv6 addresses with or without
- * square brackets.
- *
- * Return 0 on success, -1 on failure; 1 on transient failure.
- */
-MOCK_IMPL(int,
-tor_addr_lookup,(const char *name, uint16_t family, tor_addr_t *addr))
-{
-  /* Perhaps eventually this should be replaced by a tor_getaddrinfo or
-   * something.
-   */
-  int parsed_family = 0;
-
-  tor_assert(name);
-  tor_assert(addr);
-  tor_assert(family == AF_INET || family == AF_INET6 || family == AF_UNSPEC);
-
-  if (!*name) {
-    /* Empty address is an error. */
-    memset(addr, 0, sizeof(tor_addr_t));
-    return -1;
-  }
-
-  /* Is it an IP address? */
-  parsed_family = tor_addr_parse(addr, name);
-
-  if (parsed_family >= 0) {
-    /* If the IP address family matches, or was unspecified */
-    if (parsed_family == family || family == AF_UNSPEC) {
-      return 0;
-    } else {
-      /* Clear the address before returning an error. */
-      memset(addr, 0, sizeof(tor_addr_t));
-      return -1;
-    }
-  } else {
-    /* Clear the address after a failed tor_addr_parse(). */
-    memset(addr, 0, sizeof(tor_addr_t));
 #ifdef HAVE_GETADDRINFO
+
+/* Host lookup helper for tor_addr_lookup(), when getaddrinfo() is
+ * available on this system.
+ *
+ * See tor_addr_lookup() for details.
+ */
+static int
+tor_addr_lookup_host_getaddrinfo(const char *name,
+                                 uint16_t family,
+                                 tor_addr_t *addr)
+{
   int err;
   struct addrinfo *res=NULL, *res_p;
   struct addrinfo *best=NULL;
@@ -144,7 +111,19 @@ tor_addr_lookup,(const char *name, uint16_t family, tor_addr_t *addr))
     return result;
   }
   return (err == EAI_AGAIN) ? 1 : -1;
+}
+
 #else /* !(defined(HAVE_GETADDRINFO)) */
+
+/* Host lookup helper for tor_addr_lookup(), which calls getaddrinfo().
+ * Used when gethostbyname() is not available on this system.
+ *
+ * See tor_addr_lookup() for details.
+ */
+static int
+tor_addr_lookup_host_gethostbyname(const char *name,
+                                   tor_addr_t *addr)
+{
   struct hostent *ent;
   int err;
 #ifdef HAVE_GETHOSTBYNAME_R_6_ARG
@@ -168,7 +147,7 @@ tor_addr_lookup,(const char *name, uint16_t family, tor_addr_t *addr))
   err = WSAGetLastError();
 #else
   err = h_errno;
-#endif
+#endif /* defined(_WIN32) */
 #endif /* defined(HAVE_GETHOSTBYNAME_R_6_ARG) || ... */
   if (ent) {
     if (ent->h_addrtype == AF_INET) {
@@ -185,8 +164,76 @@ tor_addr_lookup,(const char *name, uint16_t family, tor_addr_t *addr))
 #else
   return (err == TRY_AGAIN) ? 1 : -1;
 #endif
+}
+
+#endif /* defined(HAVE_GETADDRINFO) */
+
+/** Similar behavior to Unix gethostbyname: resolve <b>name</b>, and set
+ * *<b>addr</b> to the proper IP address and family. The <b>family</b>
+ * argument (which must be AF_INET, AF_INET6, or AF_UNSPEC) declares a
+ * <i>preferred</i> family, though another one may be returned if only one
+ * family is implemented for this address.
+ *
+ * Like tor_addr_parse(), this function accepts IPv6 addresses with or without
+ * square brackets.
+ *
+ * Return 0 on success, -1 on failure; 1 on transient failure.
+ */
+MOCK_IMPL(int,
+tor_addr_lookup,(const char *name, uint16_t family, tor_addr_t *addr))
+{
+  /* Perhaps eventually this should be replaced by a tor_getaddrinfo or
+   * something.
+   */
+  int parsed_family = 0;
+  int result = -1;
+
+  tor_assert(name);
+  tor_assert(addr);
+  tor_assert(family == AF_INET || family == AF_INET6 || family == AF_UNSPEC);
+
+  if (!*name) {
+    /* Empty address is an error. */
+    goto permfail;
+  }
+
+  /* Is it an IP address? */
+  parsed_family = tor_addr_parse(addr, name);
+
+  if (parsed_family >= 0) {
+    /* If the IP address family matches, or was unspecified */
+    if (parsed_family == family || family == AF_UNSPEC) {
+      goto success;
+    } else {
+      goto permfail;
+    }
+  } else {
+    /* Clear the address after a failed tor_addr_parse(). */
+    memset(addr, 0, sizeof(tor_addr_t));
+#ifdef HAVE_GETADDRINFO
+    result = tor_addr_lookup_host_getaddrinfo(name, family, addr);
+    goto done;
+#else /* !(defined(HAVE_GETADDRINFO)) */
+    result = tor_addr_lookup_host_gethostbyname(name, addr);
+    goto done;
 #endif /* defined(HAVE_GETADDRINFO) */
   }
+
+ /* If we weren't successful, and haven't already set the result,
+  * assume it's a permanent failure */
+ permfail:
+  result = -1;
+  goto done;
+ success:
+  result = 0;
+
+ /* We have set the result, now it's time to clean up */
+ done:
+  if (result) {
+    /* Clear the address on error */
+    memset(addr, 0, sizeof(tor_addr_t));
+  }
+  return result;
 }
 
 /** Parse an address or address-port combination from <b>s</b>, resolve the