ibmi: Handle interface names longer than 10 chars

IBM i interface names are based off the associated line description.
Since line descriptions are objects, they have 10 character limit on
their names. However, since IBM i 7.2 interface names may be up to 16
characters long if the interface is for a a VLAN (eg. MYETHLINE1.4094).

To handle this, we must strip off a VLAN ID to get the actual line
description name, since that's what the QDCRLIND API wants. One issue
exists because line descriptions can contain periods and numbers; so
for interface names less than 10 characters long ETH2.4 could be a line
description name or it could be ETH2 with VLAN 4. We follow the
method that the XPF ioctls use: try the interface name directly first
and if an error occurs, try to strip off the VLAN ID.

https://www.ibm.com/docs/en/i/7.4?topic=ssw_ibm_i_74/apis/ioctl.htm#unotes

Fixes: https://github.com/libuv/libuv/issues/3062
PR-URL: https://github.com/libuv/libuv/pull/3144
Reviewed-By: Richard Lau <rlau@redhat.com>

src/unix/ibmi.c

@@ -26,7 +26,6 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
-#include <assert.h>
 #include <errno.h>
 
 #include <sys/types.h>
@@ -166,7 +165,7 @@ static void iconv_a2e(const char* src, unsigned char dst[], size_t length) {
 
   srclen = strlen(src);
   if (srclen > length)
-    abort();
+    srclen = length;
   for (i = 0; i < srclen; i++)
     dst[i] = a2e[src[i]];
   /* padding the remaining part with spaces */
@@ -360,6 +359,10 @@ static int get_ibmi_physical_address(const char* line, char (*phys_addr)[6]) {
   if (rc != 0)
     return rc;
 
+  if (err.bytes_available > 0) {
+    return -1;
+  }
+
   /* convert ebcdic loca_adapter_address to ascii first */
   iconv_e2a(rcvr.loca_adapter_address, mac_addr,
             sizeof(rcvr.loca_adapter_address));
@@ -443,9 +446,42 @@ int uv_interface_addresses(uv_interface_address_t** addresses, int* count) {
     }
     address->is_internal = cur->ifa_flags & IFF_LOOPBACK ? 1 : 0;
     if (!address->is_internal) {
-      int rc = get_ibmi_physical_address(address->name, &address->phys_addr);
+      int rc = -1;
-      if (rc != 0)
+      size_t name_len = strlen(address->name);
-        r = rc;
+      /* To get the associated MAC address, we must convert the address to a
+       * line description. Normally, the name field contains the line
+       * description name, but for VLANs it has the VLAN appended with a
+       * period. Since object names can also contain periods and numbers, there
+       * is no way to know if a returned name is for a VLAN or not. eg.
+       * *LIND ETH1.1 and *LIND ETH1, VLAN 1 both have the same name: ETH1.1
+       *
+       * Instead, we apply the same heuristic used by some of the XPF ioctls:
+       * - names > 10 *must* contain a VLAN
+       * - assume names <= 10 do not contain a VLAN and try directly
+       * - if >10 or QDCRLIND returned an error, try to strip off a VLAN
+       *   and try again
+       * - if we still get an error or couldn't find a period, leave the MAC as
+       *   00:00:00:00:00:00
+       */
+      if (name_len <= 10) {
+        /* Assume name does not contain a VLAN ID */
+        rc = get_ibmi_physical_address(address->name, &address->phys_addr);
+      }
+
+      if (name_len > 10 || rc != 0) {
+        /* The interface name must contain a VLAN ID suffix. Attempt to strip
+         * it off so we can get the line description to pass to QDCRLIND.
+         */
+        char* temp_name = uv__strdup(address->name);
+        char* dot = strrchr(temp_name, '.');
+        if (dot != NULL) {
+          *dot = '\0';
+          if (strlen(temp_name) <= 10) {
+            rc = get_ibmi_physical_address(temp_name, &address->phys_addr);
+          }
+        }
+        uv__free(temp_name);
+      }
     }
 
     address++;
@@ -498,4 +534,4 @@ int uv_get_process_title(char* buffer, size_t size) {
 }
 
 void uv__process_title_cleanup(void) {
-}
+}