Support gai_strerror() and tidy bgp_listener code.

Added support for EAI_XXX error names and gai_strerror() error
messages.

Tidied up bgp_listener set up to remove #if skips around the
"old" way -- so that the older code doesn't simply rot away.

1 files changed, 59 insertions, 1 deletions

diff --git a/lib/errno_names.c b/lib/errno_names.c
index 51f430a9..791f8001 100644
--- a/lib/errno_names.c
+++ b/lib/errno_names.c
@@ -21,6 +21,8 @@
 
 #include <stddef.h>
 #include <errno.h>
+#include <netdb.h>
+
 #include "errno_names.h"
 
 /*==============================================================================
@@ -291,7 +293,7 @@ static const char* errno_name_table[] =
 
 enum { errno_last = (sizeof(errno_name_table) / sizeof(char*)) - 1 } ;
 
-/*==============================================================================
+/*------------------------------------------------------------------------------
  * Lookup the name for given error number.
  *
  * Returns: address of string, or NULL if not known
@@ -308,4 +310,60 @@ errno_name_lookup(int err)
  return errno_name_table[err] ;
 } ;
 
+/*==============================================================================
+ * Table to map EAI error number to its name -- the errors generated by
+ * getaddrinfo() and getnameinfo().
+ *
+ * At least one system uses -ve numbers for these... so the following will
+ * support either +ve or -ve values, provided that all have the same sign.
+ */
+#if EAI_AGAIN < 0
+enum { eai_sgn = -1 } ;
+#else
+enum { eai_sgn = +1 } ;
+#endif
+
+#define EAINO(eai) [eai * eai_sgn] = #eai
+
+static const char* eaino_name_table[] =
+{
+  /* Error number for no error
+   *
+   *   (123456789012345), /-- no name is more than 15 characters
+   */
+  EAINO(EAI_OK),          /* No error                                   */
 
+  /* POSIX Error Numbers -- taken Open Group Base Specifications Issue 7
+   *                        IEEE Std 1003.1-2008
+   */
+  EAINO(EAI_AGAIN),       /* Temporary failure in name resolution.      */
+  EAINO(EAI_BADFLAGS),    /* Invalid value for 'ai_flags' field.        */
+  EAINO(EAI_FAIL),        /* Non-recoverable failure in name res.       */
+  EAINO(EAI_FAMILY),      /* 'ai_family' not supported.                 */
+  EAINO(EAI_MEMORY),      /* Memory allocation failure.                 */
+  EAINO(EAI_NONAME),      /* NAME or SERVICE is unknown.                */
+  EAINO(EAI_OVERFLOW),    /* Argument buffer overflow.                  */
+  EAINO(EAI_SERVICE),     /* SERVICE not supported for 'ai_socktype'.   */
+  EAINO(EAI_SOCKTYPE),    /* 'ai_socktype' not supported.               */
+  EAINO(EAI_SYSTEM),      /* System error returned in 'errno'.          */
+} ;
+
+enum { eaino_last = (sizeof(eaino_name_table) / sizeof(char*)) - 1 } ;
+
+/*------------------------------------------------------------------------------
+ * Lookup the name for given error number.
+ *
+ * Returns: address of string, or NULL if not known
+ *
+ * NB: for 0 returns "EOK".
+ *
+ * NB: async-signal-safe and thread-safe !
+ */
+extern const char*
+eaino_name_lookup(int eai)
+{
+  eai *= eai_sgn ;
+  if ((eai < 0) || (eai > eaino_last))
+    return NULL ;
+ return eaino_name_table[eai] ;
+} ;