Virgin import of bsnmp 1.4

1 files changed, 1031 insertions, 0 deletions

diff --git a/contrib/bsnmp/lib/snmpagent.c b/contrib/bsnmp/lib/snmpagent.c
new file mode 100644
index 0000000..19ac661
--- /dev/null
+++ b/contrib/bsnmp/lib/snmpagent.c
@@ -0,0 +1,1031 @@
+/*
+ * Copyright (c) 2001-2003
+ *	Fraunhofer Institute for Open Communication Systems (FhG Fokus).
+ *	All rights reserved.
+ *
+ * Author: Harti Brandt <harti@freebsd.org>
+ *
+ * Redistribution of this software and documentation and use in source and
+ * binary forms, with or without modification, are permitted provided that
+ * the following conditions are met:
+ *
+ * 1. Redistributions of source code or documentation must retain the above
+ *    copyright notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE AND DOCUMENTATION IS PROVIDED BY FRAUNHOFER FOKUS
+ * AND ITS CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * FRAUNHOFER FOKUS OR ITS CONTRIBUTORS  BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $Begemot: bsnmp/lib/snmpagent.c,v 1.14 2003/01/30 11:23:00 hbb Exp $
+ *
+ * SNMP Agent functions
+ */
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdarg.h>
+#include <string.h>
+
+#include "asn1.h"
+#include "snmp.h"
+#include "snmppriv.h"
+#include "snmpagent.h"
+
+static void snmp_debug_func(const char *fmt, ...);
+
+void (*snmp_debug)(const char *fmt, ...) = snmp_debug_func;
+
+struct snmp_node *tree;
+u_int  tree_size;
+
+/*
+ * Structure to hold dependencies during SET processing
+ * The last two members of this structure must be the
+ * dependency visible by the user and the user data.
+ */
+struct depend {
+	TAILQ_ENTRY(depend) link;
+	size_t	len;		/* size of data part */
+	snmp_depop_t	func;
+	struct snmp_dependency dep;
+	u_char	data[];
+};
+TAILQ_HEAD(depend_list, depend);
+
+/*
+ * Structure to hold atfinish functions during SET processing.
+ */
+struct finish {
+	STAILQ_ENTRY(finish) link;
+	snmp_set_finish_t func;
+	void	*arg;
+};
+STAILQ_HEAD(finish_list, finish);
+
+/*
+ * Set context
+ */
+struct context {
+	struct snmp_context	ctx;
+	struct depend_list	dlist;
+	struct finish_list	flist;
+	const struct snmp_node	*node[SNMP_MAX_BINDINGS];
+	struct snmp_scratch	scratch[SNMP_MAX_BINDINGS];
+	struct depend		*depend;
+};
+
+#define	TR(W)	(snmp_trace & SNMP_TRACE_##W)
+u_int snmp_trace = 0;
+
+static char oidbuf[ASN_OIDSTRLEN];
+
+/*
+ * Allocate a context
+ */
+struct snmp_context *
+snmp_init_context(void)
+{
+	struct context *context;
+
+	if ((context = malloc(sizeof(*context))) == NULL)
+		return (NULL);
+
+	memset(context, 0, sizeof(*context));
+	TAILQ_INIT(&context->dlist);
+	STAILQ_INIT(&context->flist);
+
+	return (&context->ctx);
+}
+
+/*
+ * Find a variable for SET/GET and the first GETBULK pass.
+ * Return the node pointer. If the search fails, set the errp to
+ * the correct SNMPv2 GET exception code.
+ */
+static struct snmp_node *
+find_node(const struct snmp_value *value, enum snmp_syntax *errp)
+{
+	struct snmp_node *tp;
+
+	if (TR(FIND))
+		snmp_debug("find: searching %s",
+		    asn_oid2str_r(&value->var, oidbuf));
+
+	/*
+	 * If we have an exact match (the entry in the table is a
+	 * sub-oid from the variable) we have found what we are for.
+	 * If the table oid is higher than the variable, there is no match.
+	 */
+	for (tp = tree; tp < tree + tree_size; tp++) {
+		if (asn_is_suboid(&tp->oid, &value->var))
+			goto found;
+		if (asn_compare_oid(&tp->oid, &value->var) >= 0)
+			break;
+	}
+
+	if (TR(FIND))
+		snmp_debug("find: no match");
+	*errp = SNMP_SYNTAX_NOSUCHOBJECT;
+	return (NULL);
+
+  found:
+	/* leafs must have a 0 instance identifier */
+	if (tp->type == SNMP_NODE_LEAF &&
+	    (value->var.len != tp->oid.len + 1 ||
+	     value->var.subs[tp->oid.len] != 0)) {
+		if (TR(FIND))
+			snmp_debug("find: bad leaf index");
+		*errp = SNMP_SYNTAX_NOSUCHINSTANCE;
+		return (NULL);
+	}
+	if (TR(FIND))
+		snmp_debug("find: found %s",
+		    asn_oid2str_r(&value->var, oidbuf));
+	return (tp);
+}
+
+static struct snmp_node *
+find_subnode(const struct snmp_value *value)
+{
+	struct snmp_node *tp;
+
+	for (tp = tree; tp < tree + tree_size; tp++) {
+		if (asn_is_suboid(&value->var, &tp->oid))
+			return (tp);
+	}
+	return (NULL);
+}
+
+/*
+ * Execute a GET operation. The tree is rooted at the global 'root'.
+ * Build the response PDU on the fly. If the return code is SNMP_RET_ERR
+ * the pdu error status and index will be set.
+ */
+enum snmp_ret
+snmp_get(struct snmp_pdu *pdu, struct asn_buf *resp_b,
+    struct snmp_pdu *resp, void *data)
+{
+	int ret;
+	u_int i;
+	struct snmp_node *tp;
+	enum snmp_syntax except;
+	struct context context;
+	enum asn_err err;
+
+	memset(&context, 0, sizeof(context));
+	context.ctx.data = data;
+
+	memset(resp, 0, sizeof(*resp));
+	strcpy(resp->community, pdu->community);
+	resp->version = pdu->version;
+	resp->type = SNMP_PDU_RESPONSE;
+	resp->request_id = pdu->request_id;
+	resp->version = pdu->version;
+
+	if (snmp_pdu_encode_header(resp_b, resp) != SNMP_CODE_OK)
+		/* cannot even encode header - very bad */
+		return (SNMP_RET_IGN);
+
+	for (i = 0; i < pdu->nbindings; i++) {
+		resp->bindings[i].var = pdu->bindings[i].var;
+		if ((tp = find_node(&pdu->bindings[i], &except)) == NULL) {
+			if (pdu->version == SNMP_V1) {
+				if (TR(GET))
+					snmp_debug("get: nosuchname");
+				pdu->error_status = SNMP_ERR_NOSUCHNAME;
+				pdu->error_index = i + 1;
+				snmp_pdu_free(resp);
+				return (SNMP_RET_ERR);
+			}
+			if (TR(GET))
+				snmp_debug("get: exception %u", except);
+			resp->bindings[i].syntax = except;
+
+		} else {
+			/* call the action to fetch the value. */
+			resp->bindings[i].syntax = tp->syntax;
+			ret = (*tp->op)(&context.ctx, &resp->bindings[i],
+			    tp->oid.len, tp->index, SNMP_OP_GET);
+			if (TR(GET))
+				snmp_debug("get: action returns %d", ret);
+
+			if (ret == SNMP_ERR_NOSUCHNAME) {
+				if (pdu->version == SNMP_V1) {
+					pdu->error_status = SNMP_ERR_NOSUCHNAME;
+					pdu->error_index = i + 1;
+					snmp_pdu_free(resp);
+					return (SNMP_RET_ERR);
+				}
+				if (TR(GET))
+					snmp_debug("get: exception noSuchInstance");
+				resp->bindings[i].syntax = SNMP_SYNTAX_NOSUCHINSTANCE;
+
+			} else if (ret != SNMP_ERR_NOERROR) {
+				pdu->error_status = SNMP_ERR_GENERR;
+				pdu->error_index = i + 1;
+				snmp_pdu_free(resp);
+				return (SNMP_RET_ERR);
+			}
+		}
+		resp->nbindings++;
+
+		err = snmp_binding_encode(resp_b, &resp->bindings[i]);
+
+		if (err == ASN_ERR_EOBUF) {
+			pdu->error_status = SNMP_ERR_TOOBIG;
+			pdu->error_index = 0;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		if (err != ASN_ERR_OK) {
+			if (TR(GET))
+				snmp_debug("get: binding encoding: %u", err);
+			pdu->error_status = SNMP_ERR_GENERR;
+			pdu->error_index = i + 1;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+	}
+
+	return (snmp_fix_encoding(resp_b, resp));
+}
+
+static struct snmp_node *
+next_node(const struct snmp_value *value, int *pnext)
+{
+	struct snmp_node *tp;
+
+	if (TR(FIND))
+		snmp_debug("next: searching %s",
+		    asn_oid2str_r(&value->var, oidbuf));
+
+	*pnext = 0;
+	for (tp = tree; tp < tree + tree_size; tp++) {
+		if (asn_is_suboid(&tp->oid, &value->var)) {
+			/* the tree OID is a sub-oid of the requested OID. */
+			if (tp->type == SNMP_NODE_LEAF) {
+				if (tp->oid.len == value->var.len) {
+					/* request for scalar type */
+					if (TR(FIND))
+						snmp_debug("next: found scalar %s",
+						    asn_oid2str_r(&tp->oid, oidbuf));
+					return (tp);
+				}
+				/* try next */
+			} else {
+				if (TR(FIND))
+					snmp_debug("next: found column %s",
+					    asn_oid2str_r(&tp->oid, oidbuf));
+				return (tp);
+			}
+		} else if (asn_is_suboid(&value->var, &tp->oid) ||
+		    asn_compare_oid(&tp->oid, &value->var) >= 0) {
+			if (TR(FIND))
+				snmp_debug("next: found %s",
+				    asn_oid2str_r(&tp->oid, oidbuf));
+			*pnext = 1;
+			return (tp);
+		}
+	}
+
+	if (TR(FIND))
+		snmp_debug("next: failed");
+
+	return (NULL);
+}
+
+static enum snmp_ret
+do_getnext(struct context *context, const struct snmp_value *inb,
+    struct snmp_value *outb, struct snmp_pdu *pdu)
+{
+	const struct snmp_node *tp;
+	int ret, next;
+
+	if ((tp = next_node(inb, &next)) == NULL)
+		goto eofMib;
+
+	/* retain old variable if we are doing a GETNEXT on an exact
+	 * matched leaf only */
+	if (tp->type == SNMP_NODE_LEAF || next)
+		outb->var = tp->oid;
+	else
+		outb->var = inb->var;
+
+	for (;;) {
+		outb->syntax = tp->syntax;
+		if (tp->type == SNMP_NODE_LEAF) {
+			/* make a GET operation */
+			outb->var.subs[outb->var.len++] = 0;
+			ret = (*tp->op)(&context->ctx, outb, tp->oid.len,
+			    tp->index, SNMP_OP_GET);
+		} else {
+			/* make a GETNEXT */
+			ret = (*tp->op)(&context->ctx, outb, tp->oid.len,
+			     tp->index, SNMP_OP_GETNEXT);
+		}
+		if (ret != SNMP_ERR_NOSUCHNAME) {
+			/* got something */
+			if (ret != SNMP_ERR_NOERROR && TR(GETNEXT))
+				snmp_debug("getnext: %s returns %u",
+				    asn_oid2str(&outb->var), ret);
+			break;
+		}
+
+		/* object has no data - try next */
+		if (++tp == tree + tree_size)
+			break;
+		outb->var = tp->oid;
+	}
+
+	if (ret == SNMP_ERR_NOSUCHNAME) {
+  eofMib:
+		outb->var = inb->var;
+		if (pdu->version == SNMP_V1) {
+			pdu->error_status = SNMP_ERR_NOSUCHNAME;
+			return (SNMP_RET_ERR);
+		}
+		outb->syntax = SNMP_SYNTAX_ENDOFMIBVIEW;
+
+	} else if (ret != SNMP_ERR_NOERROR) {
+		pdu->error_status = SNMP_ERR_GENERR;
+		return (SNMP_RET_ERR);
+	}
+	return (SNMP_RET_OK);
+}
+
+
+/*
+ * Execute a GETNEXT operation. The tree is rooted at the global 'root'.
+ * Build the response PDU on the fly. The return is:
+ */
+enum snmp_ret
+snmp_getnext(struct snmp_pdu *pdu, struct asn_buf *resp_b,
+    struct snmp_pdu *resp, void *data)
+{
+	struct context context;
+	u_int i;
+	enum asn_err err;
+	enum snmp_ret result;
+
+	memset(&context, 0, sizeof(context));
+	context.ctx.data = data;
+
+	memset(resp, 0, sizeof(*resp));
+	strcpy(resp->community, pdu->community);
+	resp->type = SNMP_PDU_RESPONSE;
+	resp->request_id = pdu->request_id;
+	resp->version = pdu->version;
+
+	if (snmp_pdu_encode_header(resp_b, resp))
+		return (SNMP_RET_IGN);
+
+	for (i = 0; i < pdu->nbindings; i++) {
+		result = do_getnext(&context, &pdu->bindings[i],
+		    &resp->bindings[i], pdu);
+
+		if (result != SNMP_RET_OK) {
+			pdu->error_index = i + 1;
+			snmp_pdu_free(resp);
+			return (result);
+		}
+
+		resp->nbindings++;
+
+		err = snmp_binding_encode(resp_b, &resp->bindings[i]);
+
+		if (err == ASN_ERR_EOBUF) {
+			pdu->error_status = SNMP_ERR_TOOBIG;
+			pdu->error_index = 0;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		if (err != ASN_ERR_OK) {
+			if (TR(GET))
+				snmp_debug("getnext: binding encoding: %u", err);
+			pdu->error_status = SNMP_ERR_GENERR;
+			pdu->error_index = i + 1;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+	}
+	return (snmp_fix_encoding(resp_b, resp));
+}
+
+enum snmp_ret
+snmp_getbulk(struct snmp_pdu *pdu, struct asn_buf *resp_b,
+    struct snmp_pdu *resp, void *data)
+{
+	struct context context;
+	u_int i;
+	int cnt;
+	u_int non_rep;
+	int eomib;
+	enum snmp_ret result;
+	enum asn_err err;
+
+	memset(&context, 0, sizeof(context));
+	context.ctx.data = data;
+
+	memset(resp, 0, sizeof(*resp));
+	strcpy(resp->community, pdu->community);
+	resp->version = pdu->version;
+	resp->type = SNMP_PDU_RESPONSE;
+	resp->request_id = pdu->request_id;
+	resp->version = pdu->version;
+
+	if (snmp_pdu_encode_header(resp_b, resp) != SNMP_CODE_OK)
+		/* cannot even encode header - very bad */
+		return (SNMP_RET_IGN);
+
+	if ((non_rep = pdu->error_status) > pdu->nbindings)
+		non_rep = pdu->nbindings;
+
+	/* non-repeaters */
+	for (i = 0; i < non_rep; i++) {
+		result = do_getnext(&context, &pdu->bindings[i],
+		    &resp->bindings[resp->nbindings], pdu);
+
+		if (result != SNMP_RET_OK) {
+			pdu->error_index = i + 1;
+			snmp_pdu_free(resp);
+			return (result);
+		}
+
+		err = snmp_binding_encode(resp_b,
+		    &resp->bindings[resp->nbindings++]);
+
+		if (err == ASN_ERR_EOBUF)
+			goto done;
+
+		if (err != ASN_ERR_OK) {
+			if (TR(GET))
+				snmp_debug("getnext: binding encoding: %u", err);
+			pdu->error_status = SNMP_ERR_GENERR;
+			pdu->error_index = i + 1;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+	}
+
+	if (non_rep == pdu->nbindings)
+		goto done;
+
+	/* repeates */
+	for (cnt = 0; cnt < pdu->error_index; cnt++) {
+		eomib = 1;
+		for (i = non_rep; i < pdu->nbindings; i++) {
+			if (cnt == 0) 
+				result = do_getnext(&context, &pdu->bindings[i],
+				    &resp->bindings[resp->nbindings], pdu);
+			else
+				result = do_getnext(&context,
+				    &resp->bindings[resp->nbindings -
+				    (pdu->nbindings - non_rep)],
+				    &resp->bindings[resp->nbindings], pdu);
+
+			if (result != SNMP_RET_OK) {
+				pdu->error_index = i + 1;
+				snmp_pdu_free(resp);
+				return (result);
+			}
+			if (resp->bindings[resp->nbindings].syntax !=
+			    SNMP_SYNTAX_ENDOFMIBVIEW)
+				eomib = 0;
+
+			err = snmp_binding_encode(resp_b,
+			    &resp->bindings[resp->nbindings++]);
+
+			if (err == ASN_ERR_EOBUF)
+				goto done;
+
+			if (err != ASN_ERR_OK) {
+				if (TR(GET))
+					snmp_debug("getnext: binding encoding: %u", err);
+				pdu->error_status = SNMP_ERR_GENERR;
+				pdu->error_index = i + 1;
+				snmp_pdu_free(resp);
+				return (SNMP_RET_ERR);
+			}
+		}
+		if (eomib)
+			break;
+	}
+
+  done:
+	return (snmp_fix_encoding(resp_b, resp));
+}
+
+/*
+ * Rollback a SET operation. Failed index is 'i'.
+ */
+static void
+rollback(struct context *context, struct snmp_pdu *pdu, u_int i)
+{
+	struct snmp_value *b;
+	const struct snmp_node *np;
+	int ret;
+
+	while (i-- > 0) {
+		b = &pdu->bindings[i];
+		np = context->node[i];
+
+		context->ctx.scratch = &context->scratch[i];
+
+		ret = (*np->op)(&context->ctx, b, np->oid.len, np->index,
+		    SNMP_OP_ROLLBACK);
+
+		if (ret != SNMP_ERR_NOERROR) {
+			snmp_error("set: rollback failed (%d) on variable %s "
+			    "index %u", ret, asn_oid2str(&b->var), i);
+			if (pdu->version != SNMP_V1) {
+				pdu->error_status = SNMP_ERR_UNDO_FAILED;
+				pdu->error_index = 0;
+			}
+		}
+	}
+}
+
+/*
+ * Commit dependencies.
+ */
+int
+snmp_dep_commit(struct snmp_context *ctx)
+{
+	struct context *context = (struct context *)ctx;
+	int ret;
+
+	TAILQ_FOREACH(context->depend, &context->dlist, link) {
+		ctx->dep = &context->depend->dep;
+
+		if (TR(SET))
+			snmp_debug("set: dependency commit %s",
+			    asn_oid2str(&ctx->dep->obj));
+
+		ret = context->depend->func(ctx, ctx->dep, SNMP_DEPOP_COMMIT);
+
+		if (ret != SNMP_ERR_NOERROR) {
+			if (TR(SET))
+				snmp_debug("set: dependency failed %d", ret);
+			return (ret);
+		}
+	}
+	return (SNMP_ERR_NOERROR);
+}
+
+/*
+ * Rollback dependencies
+ */
+int
+snmp_dep_rollback(struct snmp_context *ctx)
+{
+	struct context *context = (struct context *)ctx;
+	int ret, ret1;
+	char objbuf[ASN_OIDSTRLEN];
+	char idxbuf[ASN_OIDSTRLEN];
+
+	ret1 = SNMP_ERR_NOERROR;
+	while ((context->depend =
+	    TAILQ_PREV(context->depend, depend_list, link)) != NULL) {
+		ctx->dep = &context->depend->dep;
+
+		if (TR(SET))
+			snmp_debug("set: dependency rollback %s",
+			    asn_oid2str(&ctx->dep->obj));
+
+		ret = context->depend->func(ctx, ctx->dep, SNMP_DEPOP_ROLLBACK);
+
+		if (ret != SNMP_ERR_NOERROR) {
+			snmp_debug("set: dep rollback returns %u: %s %s", ret,
+			    asn_oid2str_r(&ctx->dep->obj, objbuf),
+			    asn_oid2str_r(&ctx->dep->idx, idxbuf));
+			if (ret1 == SNMP_ERR_NOERROR)
+				ret1 = ret;
+		}
+	}
+	return (ret1);
+}
+
+/*
+ * Do a SET operation.
+ */
+enum snmp_ret
+snmp_set(struct snmp_pdu *pdu, struct asn_buf *resp_b,
+    struct snmp_pdu *resp, void *data)
+{
+	int ret;
+	u_int i;
+	enum snmp_ret code;
+	enum asn_err asnerr;
+	struct context context;
+	const struct snmp_node *np;
+	struct finish *f;
+	struct depend *d;
+	struct snmp_value *b;
+	enum snmp_syntax except;
+
+	memset(&context, 0, sizeof(context));
+	TAILQ_INIT(&context.dlist);
+	STAILQ_INIT(&context.flist);
+	context.ctx.data = data;
+
+	memset(resp, 0, sizeof(*resp));
+	strcpy(resp->community, pdu->community);
+	resp->type = SNMP_PDU_RESPONSE;
+	resp->request_id = pdu->request_id;
+	resp->version = pdu->version;
+
+	if (snmp_pdu_encode_header(resp_b, resp))
+		return (SNMP_RET_IGN);
+
+	/* 
+	 * 1. Find all nodes, check that they are writeable and
+	 *    that the syntax is ok, copy over the binding to the response.
+	 */
+	for (i = 0; i < pdu->nbindings; i++) {
+		b = &pdu->bindings[i];
+
+		if ((np = context.node[i] = find_node(b, &except)) == NULL) {
+			/* not found altogether or LEAF with wrong index */
+			if (TR(SET))
+				snmp_debug("set: node not found %s",
+				    asn_oid2str_r(&b->var, oidbuf));
+			if (pdu->version == SNMP_V1) {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NOSUCHNAME;
+			} else if ((np = find_subnode(b)) != NULL) {
+				/* 2. intermediate object */
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NOT_WRITEABLE;
+			} else if (except == SNMP_SYNTAX_NOSUCHOBJECT) {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NO_ACCESS;
+			} else {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NO_CREATION;
+			}
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		/*
+		 * 2. write/createable?
+		 * Can check this for leafs only, because in v2 we have
+		 * to differentiate between NOT_WRITEABLE and NO_CREATION
+		 * and only the action routine for COLUMNS knows, whether
+		 * a column exists.
+		 */
+		if (np->type == SNMP_NODE_LEAF &&
+		    !(np->flags & SNMP_NODE_CANSET)) {
+			if (pdu->version == SNMP_V1) {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NOSUCHNAME;
+			} else {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_NOT_WRITEABLE;
+			}
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		/*
+		 * 3. Ensure the right syntax
+		 */
+		if (np->syntax != b->syntax) {
+			if (pdu->version == SNMP_V1) {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_BADVALUE; /* v2: wrongType */
+			} else {
+				pdu->error_index = i + 1;
+				pdu->error_status = SNMP_ERR_WRONG_TYPE;
+			}
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		/*
+		 * 4. Copy binding
+		 */
+		if (snmp_value_copy(&resp->bindings[i], b)) {
+			pdu->error_index = i + 1;
+			pdu->error_status = SNMP_ERR_GENERR;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		asnerr = snmp_binding_encode(resp_b, &resp->bindings[i]);
+		if (asnerr == ASN_ERR_EOBUF) {
+			pdu->error_index = i + 1;
+			pdu->error_status = SNMP_ERR_TOOBIG;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		} else if (asnerr != ASN_ERR_OK) {
+			pdu->error_index = i + 1;
+			pdu->error_status = SNMP_ERR_GENERR;
+			snmp_pdu_free(resp);
+			return (SNMP_RET_ERR);
+		}
+		resp->nbindings++;
+	}
+
+	code = SNMP_RET_OK;
+
+	/*
+	 * 2. Call the SET method for each node. If a SET fails, rollback
+	 *    everything. Map error codes depending on the version.
+	 */
+	for (i = 0; i < pdu->nbindings; i++) {
+		b = &pdu->bindings[i];
+		np = context.node[i];
+
+		context.ctx.var_index = i + 1;
+		context.ctx.scratch = &context.scratch[i];
+
+		ret = (*np->op)(&context.ctx, b, np->oid.len, np->index,
+		    SNMP_OP_SET);
+
+		if (TR(SET))
+			snmp_debug("set: action %s returns %d", np->name, ret);
+
+		if (pdu->version == SNMP_V1) {
+			switch (ret) {
+			  case SNMP_ERR_NO_ACCESS:
+				ret = SNMP_ERR_NOSUCHNAME;
+				break;
+			  case SNMP_ERR_WRONG_TYPE:
+				/* should no happen */
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			  case SNMP_ERR_WRONG_LENGTH:
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			  case SNMP_ERR_WRONG_ENCODING:
+				/* should not happen */
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			  case SNMP_ERR_WRONG_VALUE:
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			  case SNMP_ERR_NO_CREATION:
+				ret = SNMP_ERR_NOSUCHNAME;
+				break;
+			  case SNMP_ERR_INCONS_VALUE:
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			  case SNMP_ERR_RES_UNAVAIL:
+				ret = SNMP_ERR_GENERR;
+				break;
+			  case SNMP_ERR_COMMIT_FAILED:
+				ret = SNMP_ERR_GENERR;
+				break;
+			  case SNMP_ERR_UNDO_FAILED:
+				ret = SNMP_ERR_GENERR;
+				break;
+			  case SNMP_ERR_AUTH_ERR:
+				/* should not happen */
+				ret = SNMP_ERR_GENERR;
+				break;
+			  case SNMP_ERR_NOT_WRITEABLE:
+				ret = SNMP_ERR_NOSUCHNAME;
+				break;
+			  case SNMP_ERR_INCONS_NAME:
+				ret = SNMP_ERR_BADVALUE;
+				break;
+			}
+		}
+		if (ret != SNMP_ERR_NOERROR) {
+			pdu->error_index = i + 1;
+			pdu->error_status = ret;
+
+			rollback(&context, pdu, i);
+			snmp_pdu_free(resp);
+
+			code = SNMP_RET_ERR;
+
+			goto errout;
+		}
+	}
+
+	/*
+	 * 3. Call dependencies
+	 */
+	if (TR(SET))
+		snmp_debug("set: set operations ok");
+
+	if ((ret = snmp_dep_commit(&context.ctx)) != SNMP_ERR_NOERROR) {
+		pdu->error_status = ret;
+		pdu->error_index = context.ctx.var_index;
+
+		if ((ret = snmp_dep_rollback(&context.ctx)) != SNMP_ERR_NOERROR) {
+			if (pdu->version != SNMP_V1) {
+				pdu->error_status = SNMP_ERR_UNDO_FAILED;
+				pdu->error_index = 0;
+			}
+		}
+		rollback(&context, pdu, i);
+		snmp_pdu_free(resp);
+
+		code = SNMP_RET_ERR;
+
+		goto errout;
+	}
+
+	/*
+	 * 4. Commit and copy values from the original packet to the response.
+	 *    This is not the commit operation from RFC 1905 but rather an
+	 *    'FREE RESOURCES' operation. It shouldn't fail.
+	 */
+	if (TR(SET))
+		snmp_debug("set: commiting");
+
+	for (i = 0; i < pdu->nbindings; i++) {
+		b = &resp->bindings[i];
+		np = context.node[i];
+
+		context.ctx.var_index = i + 1;
+		context.ctx.scratch = &context.scratch[i];
+
+		ret = (*np->op)(&context.ctx, b, np->oid.len, np->index,
+		    SNMP_OP_COMMIT);
+
+		if (ret != SNMP_ERR_NOERROR)
+			snmp_error("set: commit failed (%d) on"
+			    " variable %s index %u", ret,
+			    asn_oid2str_r(&b->var, oidbuf), i);
+	}
+
+	if (snmp_fix_encoding(resp_b, resp) != SNMP_CODE_OK) {
+		snmp_error("set: fix_encoding failed");
+		snmp_pdu_free(resp);
+		code = SNMP_RET_IGN;
+	}
+
+	/*
+	 * Done
+	 */
+  errout:
+	while ((d = TAILQ_FIRST(&context.dlist)) != NULL) {
+		TAILQ_REMOVE(&context.dlist, d, link);
+		free(d);
+	}
+
+	/*
+	 * call finish function
+	 */
+	while ((f = STAILQ_FIRST(&context.flist)) != NULL) {
+		STAILQ_REMOVE_HEAD(&context.flist, link);
+		(*f->func)(&context.ctx, code != SNMP_RET_OK, f->arg);
+		free(f);
+	}
+
+	if (TR(SET))
+		snmp_debug("set: returning %d", code);
+
+	return (code);
+}
+/*
+ * Lookup a dependency. If it doesn't exist, create one
+ */
+struct snmp_dependency *
+snmp_dep_lookup(struct snmp_context *ctx, const struct asn_oid *obj,
+    const struct asn_oid *idx, size_t len, snmp_depop_t func)
+{
+	struct context *context;
+	struct depend *d;
+
+	context = (struct context *)(void *)
+	    ((char *)ctx - offsetof(struct context, ctx));
+	if (TR(DEPEND)) {
+		snmp_debug("depend: looking for %s", asn_oid2str(obj));
+		if (idx)
+			snmp_debug("depend: index is %s", asn_oid2str(idx));
+	}
+	TAILQ_FOREACH(d, &context->dlist, link)
+		if (asn_compare_oid(obj, &d->dep.obj) == 0 &&
+		    ((idx == NULL && d->dep.idx.len == 0) ||
+		     (idx != NULL && asn_compare_oid(idx, &d->dep.idx) == 0))) {
+			if(TR(DEPEND))
+				snmp_debug("depend: found");
+			return (&d->dep);
+		}
+
+	if(TR(DEPEND))
+		snmp_debug("depend: creating");
+
+	if ((d = malloc(offsetof(struct depend, dep) + len)) == NULL)
+		return (NULL);
+	memset(&d->dep, 0, len);
+
+	d->dep.obj = *obj;
+	if (idx == NULL)
+		d->dep.idx.len = 0;
+	else
+		d->dep.idx = *idx;
+	d->len = len;
+	d->func = func;
+
+	TAILQ_INSERT_TAIL(&context->dlist, d, link);
+
+	return (&d->dep);
+}
+
+/*
+ * Register a finish function.
+ */
+int
+snmp_set_atfinish(struct snmp_context *ctx, snmp_set_finish_t func, void *arg)
+{
+	struct context *context;
+	struct finish *f;
+
+	context = (struct context *)(void *)
+	    ((char *)ctx - offsetof(struct context, ctx));
+	if ((f = malloc(sizeof(struct finish))) == NULL)
+		return (-1);
+	f->func = func;
+	f->arg = arg;
+	STAILQ_INSERT_TAIL(&context->flist, f, link);
+
+	return (0);
+}
+
+/*
+ * Make an error response from a PDU. We do this without decoding the
+ * variable bindings. This means we can sent the junk back to a caller
+ * that has sent us junk in the first place. 
+ */
+enum snmp_ret
+snmp_make_errresp(const struct snmp_pdu *pdu, struct asn_buf *pdu_b,
+    struct asn_buf *resp_b)
+{
+	asn_len_t len;
+	struct snmp_pdu resp;
+	enum asn_err err;
+	enum snmp_code code;
+
+	memset(&resp, 0, sizeof(resp));
+
+	/* Message sequence */
+	if (asn_get_sequence(pdu_b, &len) != ASN_ERR_OK)
+		return (SNMP_RET_IGN);
+	if (pdu_b->asn_len < len)
+		return (SNMP_RET_IGN);
+
+	err = snmp_parse_message_hdr(pdu_b, &resp, &len);
+	if (ASN_ERR_STOPPED(err))
+		return (SNMP_RET_IGN);
+	if (pdu_b->asn_len < len)
+		return (SNMP_RET_IGN);
+	pdu_b->asn_len = len;
+
+	err = snmp_parse_pdus_hdr(pdu_b, &resp, &len);
+	if (ASN_ERR_STOPPED(err))
+		return (SNMP_RET_IGN);
+	if (pdu_b->asn_len < len)
+		return (SNMP_RET_IGN);
+	pdu_b->asn_len = len;
+
+	/* now we have the bindings left - construct new message */
+	resp.error_status = pdu->error_status;
+	resp.error_index = pdu->error_index;
+	resp.type = SNMP_PDU_RESPONSE;
+
+	code = snmp_pdu_encode_header(resp_b, &resp);
+	if (code != SNMP_CODE_OK)
+		return (SNMP_RET_IGN);
+
+	if (pdu_b->asn_len > resp_b->asn_len)
+		/* too short */
+		return (SNMP_RET_IGN);
+	(void)memcpy(resp_b->asn_ptr, pdu_b->asn_cptr, pdu_b->asn_len);
+	resp_b->asn_len -= pdu_b->asn_len;
+	resp_b->asn_ptr += pdu_b->asn_len;
+
+	code = snmp_fix_encoding(resp_b, &resp);
+	if (code != SNMP_CODE_OK)
+		return (SNMP_RET_IGN);
+
+	return (SNMP_RET_OK);
+}
+
+static void
+snmp_debug_func(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	fprintf(stderr, "\n");
+}