Started with getnext and ensure zero length identifiers are accepted.

src/core/snmp/mib_structs.c

@@ -32,11 +32,41 @@
  * Author: Christiaan Simons <christiaan.simons@axon.tv>
  */
 
-#include "lwip/opt.h"
 #include "lwip/snmp_structs.h"
 
 #if LWIP_SNMP
 
+/** .iso.org.dod.internet address prefix, @see snmp_iso_*() */
+const s32_t prefix[4] = {1, 3, 6, 1};
+
+#define NODE_STACK_SIZE (LWIP_SNMP_OBJ_ID_LEN)
+static u8_t node_stack_cnt = 0;
+static struct mib_node* node_stack[NODE_STACK_SIZE];
+
+static void
+push_node(struct mib_node* node)
+{
+  if (node_stack_cnt < NODE_STACK_SIZE)
+  {
+    node_stack[node_stack_cnt] = node;
+    node_stack_cnt++;
+  }
+}
+
+static struct mib_node*
+pop_node(void)
+{
+  if (node_stack_cnt > 0)
+  {
+    node_stack_cnt--;
+    return node_stack[node_stack_cnt];
+  }
+  else
+  {
+    return NULL;
+  }
+}
+
 /**
  * Searches tree for the supplied (scalar?) object identifier.
  *
@@ -60,6 +90,8 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
       struct mib_array_node *an;
       u16_t i;
 
+      if (ident_len > 0)
+      { 
         /* array node (internal ROM or RAM, fixed length) */
         an = (struct mib_array_node *)node;
         i = 0;
@@ -68,8 +100,6 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
           i++;
         }
         if (i < an->maxlength)
-      {
-        if (ident_len > 0)
         {
           /* found it, if available proceed to child, otherwise inspect leaf */
           LWIP_DEBUGF(SNMP_MIB_DEBUG,("an->objid[%"U16_F"]==%"S32_F" *ident==%"S32_F,i,an->objid[i],*ident));
@@ -102,15 +132,15 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
         }
         else
         {
-          /* search failed, short object identifier (nosuchname) */
+          /* search failed, identifier mismatch (nosuchname) */
-          LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, short object identifier"));
+          LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
           return NULL;
         }
       }
       else
       {
-        /* search failed, identifier mismatch (nosuchname) */
+        /* search failed, short object identifier (nosuchname) */
-        LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
+        LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, short object identifier"));
         return NULL;
       }
     }
@@ -119,6 +149,8 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
       struct mib_list_rootnode *lrn;
       struct mib_list_node *ln;
 
+      if (ident_len > 0)
+      {
         /* list root node (internal 'RAM', variable length) */
         lrn = (struct mib_list_rootnode *)node;
         ln = lrn->head;
@@ -128,8 +160,6 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
           ln = ln->next;
         }
         if (ln != NULL)
-      {
-        if (ident_len > 0)
         {
           /* found it, proceed to child */;
           LWIP_DEBUGF(SNMP_MIB_DEBUG,("ln->objid==%"S32_F" *ident==%"S32_F,ln->objid,*ident));
@@ -158,15 +188,15 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
         }
         else
         {
-          /* search failed, short object identifier (nosuchname) */
+          /* search failed */
-          LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, short object identifier"));
+          LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
           return NULL;
         }
       }
       else
       {
-        /* search failed */
+        /* search failed, short object identifier (nosuchname) */
-        LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
+        LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, short object identifier"));
         return NULL;
       }
     }
@@ -175,6 +205,8 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
       struct mib_external_node *en;
       u16_t i;
 
+      if (ident_len > 0)
+      { 
         /* external node (addressing and access via functions) */
         en = (struct mib_external_node *)node;
         i = 0;
@@ -183,8 +215,6 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
           i++;
         }
         if (i < en->count)
-      {
-        if (ident_len > 0)
         {
           if (en->get_nptr(i) == NULL)
           {
@@ -202,6 +232,13 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
           }
         }
         else
+        {
+          /* search failed */
+          LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
+          return NULL;
+        }
+      }
+      else
       {
         /* search failed, short object identifier (nosuchname) */
         LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed, short object identifier"));
@@ -210,11 +247,111 @@ snmp_search_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct obj
     }
     else
     {
-        /* search failed */
+      /* unknown node_type */
+      LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node_type "U16_F" unkown",(u16_t)node_type));
+      return NULL;
+    }
+  }
+  /* done, found nothing */
+  LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node==%p",(void*)node));
+  return NULL;
+}
+
+/**
+ * Tree expansion.
+ *
+ */
+struct mib_node *
+snmp_expand_tree(struct mib_node *node, u8_t ident_len, s32_t *ident, struct snmp_obj_id *oidret)
+{
+  u8_t node_type;
+
+  /* reset stack */
+  node_stack_cnt = 0;
+
+  while (node != NULL)
+  {
+    node_type = node->node_type;
+    if ((node_type == MIB_NODE_AR) || (node_type == MIB_NODE_RA))
+    {
+      struct mib_array_node *an;
+      u16_t i;
+
+      /* array node (internal ROM or RAM, fixed length) */
+      an = (struct mib_array_node *)node;
+      if (ident_len > 0)
+      {
+        i = 0;
+        while ((i < an->maxlength) && (an->objid[i] < *ident))
+        {
+          i++;
+        }
+        if (i < an->maxlength)
+        {
+          LWIP_DEBUGF(SNMP_MIB_DEBUG,("an->objid[%"U16_F"]==%"S32_F" *ident==%"S32_F,i,an->objid[i],*ident));
+
+          /* add identifier to oidret */
+          oidret->id[oidret->len] = an->objid[i];
+          (oidret->len)++;
+        
+          if (an->nptr[i] == NULL)
+          {
+            /* leaf node */
+            /*
+               if scalar: add '.0'
+               @todo if tabular: if not empty add first index, nextThing otherwise
+            */
+            oidret->id[oidret->len] = 0;
+            (oidret->len)++;
+            return (struct mib_node*)an;
+          }
+          else
+          {
+            /* follow next child pointer */
+            ident_len--;
+            ident++;
+            node = an->nptr[i];
+          }
+        }
+        else
+        {
+          /* @todo return to parent */
           LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed *ident==%"S32_F,*ident));
           return NULL;
         }
       }
+      else
+      {
+        /* short object identifier, complete it */
+        
+        /* add leftmost '.Thing' */
+        oidret->id[oidret->len] = an->objid[0];
+        (oidret->len)++;
+                
+        if (an->nptr[0] == NULL)
+        {
+          /* leaf node */
+          /*
+             if scalar: add '.0'
+             @todo if tabular: if not empty add first index, nextThing otherwise
+           */
+          oidret->id[oidret->len] = 0;
+          (oidret->len)++;
+          return (struct mib_node*)an;
+        }
+        else
+        {
+          /* no leaf, continue */
+          node = an->nptr[0];
+        }
+      }
+    }
+    else
+    {
+      /* unknown/unhandled node_type */
+      LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node_type "U16_F" unkown",(u16_t)node_type));
+      return NULL;
+    }
   }
   /* done, found nothing */
   LWIP_DEBUGF(SNMP_MIB_DEBUG,("search failed node==%p",(void*)node));
@@ -243,4 +380,51 @@ snmp_iso_prefix_tst(u8_t ident_len, s32_t *ident)
   }
 }
 
+/**
+ * Expands object identifier to the iso.org.dod.internet
+ * prefix for use in getnext operation.
+ *
+ * @param ident_len the length of the supplied object identifier
+ * @param ident points to the array of sub identifiers
+ * @param oidret points to returned expanded object identifier
+ * @return 1 if it matches, 0 otherwise
+ *
+ * @note ident_len 0 is allowed, expanding to the first known object id!!
+ */
+u8_t
+snmp_iso_prefix_expand(u8_t ident_len, s32_t *ident, struct snmp_obj_id *oidret)
+{
+  const s32_t *prefix_ptr;
+  s32_t *ret_ptr;
+  u8_t i;
+
+  i = 0;
+  prefix_ptr = &prefix[0];
+  ret_ptr = &oidret->id[0];
+  ident_len = ((ident_len < 4)?ident_len:4);
+  while ((i < ident_len) && ((*ident) <= (*prefix_ptr)))
+  {
+    *ret_ptr++ = *prefix_ptr++;
+    ident++;
+    i++;
+  }
+  if (i == ident_len)
+  {
+    /* match, complete missing bits */
+    while (i < 4)
+    {
+      *ret_ptr++ = *prefix_ptr++;
+      i++;
+    }
+    oidret->len = i;
+    return 1;
+  }
+  else
+  {
+    /* i != ident_len */
+    return 0;
+  }
+}
+
 #endif /* LWIP_SNMP */
+

src/core/snmp/msg_in.c

@@ -50,7 +50,6 @@
 
 #if LWIP_SNMP
 
-#define LWIP_SNMP_DBG_LOOPBACK_TST 0
 #define SNMP_CONCURRENT_REQUESTS 2
 
 /* public (non-static) constants */
@@ -102,6 +101,7 @@ snmp_init(void)
   trap_msg.pcb = snmp1_pcb;
 }
 
+#if 0
 /**
  * called for each variable binding (also for the fist one)
  */
@@ -150,13 +150,10 @@ snmp_msg_event(struct snmp_msg_pstat *msg_ps)
       else
       {
         /* mn == NULL, noSuchName */
+        snmp_varbind_list_free(&msg_ps->outvb);
+        msg_ps->outvb = msg_ps->invb;
         msg_ps->error_status = SNMP_ES_NOSUCHNAME;
         msg_ps->error_index = 1 + msg_ps->vb_idx;
-        msg_ps->outvb.head = NULL;
-        msg_ps->outvb.tail = NULL;
-        msg_ps->outvb.count = 0;
-        msg_ps->outvb.seqlen = 0;
-        msg_ps->outvb.seqlenlen = 1;
         snmp_send_response(msg_ps);
         msg_ps->state = SNMP_MSG_EMPTY;
       }
@@ -179,6 +176,7 @@ snmp_msg_event(struct snmp_msg_pstat *msg_ps)
   {
   }
 }
+#endif
 
 /* lwIP UDP receive callback function */
 static void
@@ -264,34 +262,99 @@ snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr,
             }
             if (mn != NULL)
             {
-              if (msg_ps->invb.head->value != NULL)
+              struct snmp_varbind *vb;
+
+              /* allocate output varbind */
+              vb = (struct snmp_varbind *)mem_malloc(sizeof(struct snmp_varbind));
+              if (vb != NULL)
               {
-                LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv free value before vb recycle"));
+                vb->next = NULL;
-                mem_free(msg_ps->invb.head->value);
+                vb->prev = NULL;
-              }            
+
-              msg_ps->invb.head->value_type = object_def.asn_type;
+                /* move name from invb to outvb */
-              msg_ps->invb.head->value_len = object_def.v_len;
+                vb->ident = msg_ps->invb.head->ident;
-              msg_ps->invb.head->value = mem_malloc(object_def.v_len);
+                vb->ident_len = msg_ps->invb.head->ident_len;
-              if (msg_ps->invb.head->value != NULL)
+                /* ensure this memory is refereced once only */
+                msg_ps->invb.head->ident = NULL;
+                msg_ps->invb.head->ident_len = 0;
+                
+                vb->value_type = object_def.asn_type;
+                vb->value_len = object_def.v_len;
+                vb->value = mem_malloc(object_def.v_len);                
+                if (vb->value != NULL)
                 {
-                mn->get_value(&object_def, object_def.v_len, msg_ps->invb.head->value);
+                  mn->get_value(&object_def, object_def.v_len, vb->value);
+                  snmp_varbind_tail_add(&msg_ps->outvb, vb);
                 }
                 else
                 {
                   LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv couldn't allocate variable space"));
                 }
-              msg_ps->outvb = msg_ps->invb;
+              }
+              else
+              {
+                 LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv couldn't allocate outvb space"));
+              }
             }
             else
             {
               /* mn == NULL, noSuchName */
+              /* @todo move used names back from outvb to invb */
+              snmp_varbind_list_free(&msg_ps->outvb);
+              msg_ps->outvb = msg_ps->invb;
+              msg_ps->error_status = SNMP_ES_NOSUCHNAME;
+              msg_ps->error_index = 1 + msg_ps->vb_idx;
+            }
+          }
+          else if (msg_ps->rt == SNMP_ASN1_PDU_GET_NEXT_REQ)
+          {
+            struct snmp_obj_id oid;
+
+            if (snmp_iso_prefix_expand(msg_ps->invb.head->ident_len, msg_ps->invb.head->ident, &oid))
+            {
+              /** @todo expand tree and complete oid */
+#if 1
+              if (msg_ps->invb.head->ident_len > 3)
+              {
+                /* can offset ident_len and ident */
+                mn = snmp_expand_tree((struct mib_node*)&internet,
+                                      msg_ps->invb.head->ident_len - 4,
+                                      msg_ps->invb.head->ident + 4, &oid);
+              }
+              else
+              {
+                /* can't offset ident_len -4, ident + 4 */
+                mn = snmp_expand_tree((struct mib_node*)&internet, 0, NULL, &oid);
+              }
+#else
+              mn = (struct mib_node*)&internet;
+#endif
+            }
+            else
+            {
+              mn = NULL;
+            }
+            if (mn != NULL)
+            {
+              struct snmp_varbind *vb;
+
+              vb = snmp_varbind_alloc(&oid, (SNMP_ASN1_UNIV | SNMP_ASN1_PRIMIT | SNMP_ASN1_NUL), 0);
+              if (vb != NULL)
+              {
+                snmp_varbind_tail_add(&msg_ps->outvb, vb);
+              }
+              else
+              {
+                LWIP_DEBUGF(SNMP_MSG_DEBUG, ("snmp_recv couldn't allocate outvb space"));
+              }
+            }
+            else
+            {
+              /* mn == NULL, noSuchName */
+              snmp_varbind_list_free(&msg_ps->outvb);
+              msg_ps->outvb = msg_ps->invb;
               msg_ps->error_status = SNMP_ES_NOSUCHNAME;
               msg_ps->error_index = 1 + msg_ps->vb_idx;
-              msg_ps->outvb.head = NULL;
-              msg_ps->outvb.tail = NULL;
-              msg_ps->outvb.count = 0;
-              msg_ps->outvb.seqlen = 0;
-              msg_ps->outvb.seqlenlen = 1;
             }
           }
           else
@@ -322,8 +385,8 @@ snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr,
           }
           /* free varbinds (if available) */
           snmp_varbind_list_free(&msg_ps->invb);
+          snmp_varbind_list_free(&msg_ps->outvb);
           msg_ps->state = SNMP_MSG_EMPTY;
-
         }
         else
         {
@@ -770,6 +833,8 @@ snmp_varbind_alloc(struct snmp_obj_id *oid, u8_t type, u8_t len)
     vb->prev = NULL;
     i = oid->len;
     vb->ident_len = i;
+    if (i > 0)
+    {
       /* allocate array of s32_t for our object identifier */
       vb->ident = (s32_t*)mem_malloc(sizeof(s32_t) * i);
       if (vb->ident == NULL)
@@ -782,6 +847,12 @@ snmp_varbind_alloc(struct snmp_obj_id *oid, u8_t type, u8_t len)
         i--;
         vb->ident[i] = oid->id[i];
       }
+    }
+    else
+    {
+      /* i == 0, pass zero length object identifier */
+      vb->ident = NULL;
+    }
     vb->value_type = type;
     vb->value_len = len;
     if (len > 0)
@@ -789,8 +860,11 @@ snmp_varbind_alloc(struct snmp_obj_id *oid, u8_t type, u8_t len)
       /* allocate raw bytes for our object value */
       vb->value = mem_malloc(len);
       if (vb->value == NULL)
+      {
+        if (vb->ident != NULL)
         {
           mem_free(vb->ident);
+        }
         mem_free(vb);
         return NULL;
       }
@@ -821,15 +895,18 @@ snmp_varbind_free(struct snmp_varbind *vb)
 static void
 snmp_varbind_list_free(struct snmp_varbind_root *root)
 {
-  struct snmp_varbind *vb;
+  struct snmp_varbind *vb, *prev;
 
   vb = root->tail;
   while ( vb != NULL )
   {
+    prev = vb->prev;
     snmp_varbind_free(vb);
-    vb = vb->prev;
+    vb = prev;
   }
   root->count = 0;
+  root->head = NULL;
+  root->tail = NULL;
 }
 
 static void