Don't use is_int() since it doesn't link well on all platforms

Just create an normal API function in strings.h that does the same thing
just to be safe.

ASTERISK-17146


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@341379 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -264,7 +264,6 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/cel.h"
 #include "asterisk/data.h"
 #include "asterisk/aoc.h"
-#include "asterisk/pval.h"
 #include "sip/include/sip.h"
 #include "sip/include/globals.h"
 #include "sip/include/config_parser.h"
@@ -5273,7 +5272,7 @@ static int create_addr(struct sip_pvt *dialog, const char *opeer, struct ast_soc
 		dialog->relatedpeer = ref_peer(peer, "create_addr: setting dialog's relatedpeer pointer");
 		unref_peer(peer, "create_addr: unref peer from find_peer hashtab lookup");
 		return res;
-	} else if (is_int(peername)) {
+	} else if (ast_check_digits(peername)) {
 		/* Although an IPv4 hostname *could* be represented as a 32-bit integer, it is uncommon and
 		 * it makes dialing SIP/${EXTEN} for a peer that isn't defined resolve to an IP that is
 		 * almost certainly not intended. It is much better to just reject purely numeric hostnames */

include/asterisk/strings.h

@@ -871,6 +871,25 @@ int __attribute__((format(printf, 3, 4))) ast_str_append(
 }
 )
 
+/*!
+ * \brief Check if a string is only digits
+ *
+ * \retval 1 The string contains only digits
+ * \retval 0 The string contains non-digit characters
+ */
+AST_INLINE_API(
+int ast_check_digits(char *arg),
+{
+	char *s;
+	for (s=arg; *s; s++) {
+		if (*s < '0' || *s > '9') {
+			return 0;
+		}
+	}
+	return 1;
+}
+)
+
 /*!
  * \brief Compute a hash value on a string
  *