tests: Introduce afstest_MyHostAddr

Several places resolve the local hostname into an IP address.
Consolidate these into a single function (gethostaddr), and add the
function afstest_MyHostAddr, which caches the IP and bails if we can't
resolve our hostname.

Change-Id: I7f71cd136796e4395c639eed8dd8eb19a7b9beec
Reviewed-on: https://gerrit.openafs.org/14802
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>

tests/common/common.h

@@ -82,6 +82,7 @@ extern int afstest_IsLoopbackNetworkDefault(void);
 extern int afstest_SkipTestsIfLoopbackNetIsDefault(void);
 extern void afstest_SkipTestsIfBadHostname(void);
 extern void afstest_SkipTestsIfServerRunning(char *name);
+extern afs_uint32 afstest_MyHostAddr(void);
 
 /* misc.c */
 extern char *afstest_GetProgname(char **argv);

tests/common/config.c

@@ -63,10 +63,10 @@ char *
 afstest_BuildTestConfig(void) {
     char *dir = NULL;
     FILE *file;
-    struct hostent *host;
-    char hostname[255];
     struct in_addr iaddr;
 
+    memset(&iaddr, 0, sizeof(iaddr));
+
     dir = afstest_mkdtemp();
     if (dir == NULL) {
 	goto fail;
@@ -75,13 +75,7 @@ afstest_BuildTestConfig(void) {
     /* Work out which IP address to use in our CellServDB. We figure this out
      * according to the IP address which ubik is most likely to pick for one of
      * our db servers */
-
-    gethostname(hostname, sizeof(hostname));
-    host = gethostbyname(hostname);
-    if (!host)
-	return NULL;
-
-    memcpy(&iaddr, host->h_addr, 4);
+    iaddr.s_addr = afstest_MyHostAddr();
 
     file = openConfigFile(dir, "CellServDB");
     fprintf(file, ">example.org # An example cell\n");

tests/common/network.c

@@ -9,6 +9,30 @@
 #include <tests/tap/basic.h>
 #include "common.h"
 
+static afs_uint32
+gethostaddr(void)
+{
+    char hostname[256];
+    struct hostent *host;
+    static afs_uint32 addr = 0;
+
+    if (addr != 0) {
+	return addr;
+    }
+
+    memset(hostname, 0, sizeof(hostname));
+
+    gethostname(hostname, sizeof(hostname));
+    host = gethostbyname(hostname);
+    if (host == NULL) {
+	diag("gethostbyname(%s) error: %d", hostname, h_errno);
+	return 0;
+    }
+
+    memcpy(&addr, host->h_addr, sizeof(addr));
+    return addr;
+}
+
 /*!
  * Check if the current machine's hostname resolves to the loopback
  * network.
@@ -16,16 +40,10 @@
 int
 afstest_IsLoopbackNetworkDefault(void)
 {
-    char hostname[MAXHOSTCHARS];
-    afs_uint32 addr;
-    struct hostent *host;
-
-    gethostname(hostname, sizeof(hostname));
-    host = gethostbyname(hostname);
-    if (!host) {
-	skip_all("Can't resolve hostname %s\n", hostname);
+    afs_uint32 addr = gethostaddr();
+    if (addr == 0) {
+	skip_all("Can't resolve hostname");
     }
-    memcpy(&addr, host->h_addr, sizeof(addr));
 
     return(rx_IsLoopbackAddr(ntohl(addr)));
 }
@@ -53,13 +71,8 @@ afstest_SkipTestsIfLoopbackNetIsDefault(void)
 void
 afstest_SkipTestsIfBadHostname(void)
 {
-    char hostname[MAXHOSTCHARS];
-    struct hostent *host;
-
-    gethostname(hostname, sizeof(hostname));
-    host = gethostbyname(hostname);
-    if (!host)
-	skip_all("Can't resolve hostname %s\n", hostname);
+    if (gethostaddr() == 0)
+	skip_all("Can't resolve hostname");
 }
 
 /*!
@@ -102,3 +115,18 @@ afstest_SkipTestsIfServerRunning(char *name)
     }
     close(sock);
 }
+
+/*!
+ * Get the IP address of the local machine, for use with mock CellServDBs, etc.
+ *
+ * @return ipv4 address in net-byte order
+ */
+afs_uint32
+afstest_MyHostAddr(void)
+{
+    afs_uint32 addr = gethostaddr();
+    if (addr == 0) {
+	bail("cannot resolve hostname");
+    }
+    return addr;
+}