Merge branch 'develop' into bugfix/link-stats

examples/snmp-server/Makefile

+CONTIKI_PROJECT = snmp-server 
+all: $(CONTIKI_PROJECT)
+
+MODULES += os/net/app-layer/snmp
+
+MODULES_REL += ./resources
+
+CONTIKI = ../..
+
+include $(CONTIKI)/Makefile.include

examples/snmp-server/project-conf.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+#define LOG_CONF_LEVEL_SNMP     LOG_LEVEL_DBG

examples/snmp-server/resources/snmp-SNMP-MIB-2-System.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+
+#include "snmp-api.h"
+
+/*---------------------------------------------------------------------------*/
+static void
+sysDescr_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysDescr, sysDescr_handler, 1, 3, 6, 1, 2, 1, 1, 1, 0);
+
+static void
+sysDescr_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_string(varbind, oid, CONTIKI_VERSION_STRING);
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysObjectID_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysObjectID, sysObjectID_handler, 1, 3, 6, 1, 2, 1, 1, 2, 0);
+
+static void
+sysObjectID_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  OID(sysObjectID_oid, 1, 3, 6, 1, 4, 1, 54352);
+  snmp_api_set_oid(varbind, oid, sysObjectID_oid);
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysUpTime_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysUpTime, sysUpTime_handler, 1, 3, 6, 1, 2, 1, 1, 3, 0);
+
+static void
+sysUpTime_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_time_ticks(varbind, oid, clock_seconds() * 100);
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysContact_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysContact, sysContact_handler, 1, 3, 6, 1, 2, 1, 1, 4, 0);
+
+static void
+sysContact_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_string(varbind, oid, "Contiki-NG, https://github.com/contiki-ng/contiki-ng");
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysName_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysName, sysName_handler, 1, 3, 6, 1, 2, 1, 1, 5, 0);
+
+static void
+sysName_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_string(varbind, oid, "Contiki-NG - "CONTIKI_TARGET_STRING);
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysLocation_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysLocation, sysLocation_handler, 1, 3, 6, 1, 2, 1, 1, 6, 0);
+
+static void
+sysLocation_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_string(varbind, oid, "");
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+static void
+sysServices_handler(snmp_varbind_t *varbind, uint32_t *oid);
+
+MIB_RESOURCE(sysServices, sysServices_handler, 1, 3, 6, 1, 2, 1, 1, 7, 0);
+
+static void
+sysServices_handler(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  snmp_api_set_time_ticks(varbind, oid, clock_seconds() * 100);
+}
+/*---------------------------------------------------------------------------*/

examples/snmp-server/snmp-server.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+#include "snmp-api.h"
+
+/*---------------------------------------------------------------------------*/
+PROCESS_NAME(snmp_server_process);
+AUTOSTART_PROCESSES(&snmp_server_process);
+/*---------------------------------------------------------------------------*/
+
+extern snmp_mib_resource_t
+  sysDescr,
+  sysObjectID,
+  sysUpTime,
+  sysContact,
+  sysName,
+  sysLocation,
+  sysServices;
+
+/*---------------------------------------------------------------------------*/
+
+PROCESS(snmp_server_process, "SNMP Server");
+
+/*---------------------------------------------------------------------------*/
+PROCESS_THREAD(snmp_server_process, ev, data)
+{
+
+  PROCESS_BEGIN();
+
+  snmp_api_add_resource(&sysDescr);
+  snmp_api_add_resource(&sysObjectID);
+  snmp_api_add_resource(&sysUpTime);
+  snmp_api_add_resource(&sysContact);
+  snmp_api_add_resource(&sysName);
+  snmp_api_add_resource(&sysLocation);
+  snmp_api_add_resource(&sysServices);
+
+  PROCESS_END();
+}
+/*---------------------------------------------------------------------------*/

os/contiki-main.c

@@ -50,6 +50,7 @@
 
 #include "net/queuebuf.h"
 #include "net/app-layer/coap/coap-engine.h"
+#include "net/app-layer/snmp/snmp.h"
 #include "services/rpl-border-router/rpl-border-router.h"
 #include "services/orchestra/orchestra.h"
 #include "services/shell/serial-shell.h"
@@ -147,6 +148,11 @@ main(void)
   LOG_DBG("With CoAP\n");
 #endif /* BUILD_WITH_SHELL */
 
+#if BUILD_WITH_SNMP
+  snmp_init();
+  LOG_DBG("With SNMP\n");
+#endif /* BUILD_WITH_SNMP */
+
 #if BUILD_WITH_SIMPLE_ENERGEST
   simple_energest_init();
 #endif /* BUILD_WITH_SIMPLE_ENERGEST */

os/net/app-layer/snmp/module-macros.h

+#define BUILD_WITH_SNMP 1

os/net/app-layer/snmp/snmp-api.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp-api.h"
+
+#include "snmp-message.h"
+#include "snmp-ber.h"
+#include "snmp-oid.h"
+
+static void
+snmp_api_replace_oid(snmp_varbind_t *varbind, uint32_t *oid)
+{
+  uint8_t i;
+
+  i = 0;
+  while(oid[i] != ((uint32_t)-1)) {
+    varbind->oid[i] = oid[i];
+    i++;
+  }
+  varbind->oid[i] = ((uint32_t)-1);
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_api_set_string(snmp_varbind_t *varbind, uint32_t *oid, char *string)
+{
+
+  snmp_api_replace_oid(varbind, oid);
+  varbind->value_type = BER_DATA_TYPE_OCTET_STRING;
+  varbind->value.string.string = string;
+  varbind->value.string.length = strlen(string);
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_api_set_time_ticks(snmp_varbind_t *varbind, uint32_t *oid, uint32_t integer)
+{
+
+  snmp_api_replace_oid(varbind, oid);
+  varbind->value_type = SNMP_DATA_TYPE_TIME_TICKS;
+  varbind->value.integer = integer;
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_api_set_oid(snmp_varbind_t *varbind, uint32_t *oid, uint32_t *ret_oid)
+{
+
+  snmp_api_replace_oid(varbind, oid);
+  varbind->value_type = BER_DATA_TYPE_OID;
+  varbind->value.oid = ret_oid;
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_api_add_resource(snmp_mib_resource_t *new_resource)
+{
+  return snmp_mib_add(new_resource);
+}

os/net/app-layer/snmp/snmp-api.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      The public API for the Contiki-NG SNMP implementation
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_API_H_
+#define SNMP_API_H_
+
+#include "snmp.h"
+#include "snmp-mib.h"
+
+/**
+ * \defgroup SNMPAPI This is the SNMP Public API
+ * @{
+ *
+ * This group contains all the functions that can be used outside the OS level.
+ * The function outside this header can be changed without notice
+ */
+
+/**
+ * @brief The MIB resource handler typedef
+ *
+ * @param varbind The varbind that is being changed
+ * @param oid The oid from the resource
+ */
+typedef void (*snmp_mib_resource_handler_t)(snmp_varbind_t *varbind, uint32_t *oid);
+
+/**
+ * @brief The MIB Resource struct
+ */
+typedef struct snmp_mib_resource_s snmp_mib_resource_t;
+
+/**
+ * @brief Initializes statically an oid with the "null" terminator
+ *
+ * @remarks This should be used inside handlers when declaring an oid
+ *
+ * @param name A name for the oid
+ * @param ... The Oid (comma-separeted)
+ */
+#define OID(name, ...) \
+  static uint32_t name[] = { __VA_ARGS__, -1 };
+
+/**
+ * @brief Declare a MIB resource
+ *
+ * @param name A name for the MIB resource
+ * @param handler The handler function for this resource
+ * @param ... The OID (comma-separated)
+ */
+#define MIB_RESOURCE(name, handler, ...) \
+  uint32_t name##_oid[] = { __VA_ARGS__, -1 }; \
+  snmp_mib_resource_t name = { NULL, name##_oid, handler };
+
+/**
+ * @brief Function to set a varbind with a string
+ *
+ * This function should be used inside a handler to set the varbind correctly
+ *
+ * @param varbind The varbind from the handler
+ * @param oid The oid from the handler
+ * @param string The string
+ */
+void
+snmp_api_set_string(snmp_varbind_t *varbind, uint32_t *oid, char *string);
+
+/**
+ * @brief Function to set a varbind with a time tick
+ *
+ * This function should be used inside a handler to set the varbind correctly
+ *
+ * @param varbind The varbind from the handler
+ * @param oid The oid from the handler
+ * @param integer The time tick value
+ */
+void
+snmp_api_set_time_ticks(snmp_varbind_t *varbind, uint32_t *oid, uint32_t integer);
+
+/**
+ * @brief Function to set a varbind with a oid
+ *
+ * This function should be used inside a handler to set the varbind correctly
+ *
+ * @param varbind The varbind from the handler
+ * @param oid The oid from the handler
+ * @param ret_oid The oid value
+ */
+void
+snmp_api_set_oid(snmp_varbind_t *varbind, uint32_t *oid, uint32_t *ret_oid);
+
+/**
+ * @brief Function to add a new resource
+ *
+ * @param new_resource The resource
+ */
+void
+snmp_api_add_resource(snmp_mib_resource_t *new_resource);
+
+/** @}*/
+
+#endif /* SNMP_API_H_ */
+/** @} */

os/net/app-layer/snmp/snmp-ber.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp.h"
+#include "snmp-ber.h"
+
+#define LOG_MODULE "SNMP [ber]"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_type(unsigned char *out, uint32_t *out_len, uint8_t type)
+{
+  *out-- = type;
+  (*out_len)++;
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_length(unsigned char *out, uint32_t *out_len, uint8_t length)
+{
+  *out-- = length;
+  (*out_len)++;
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_integer(unsigned char *out, uint32_t *out_len, uint32_t number)
+{
+  uint32_t original_out_len;
+
+  original_out_len = *out_len;
+  do {
+    (*out_len)++;
+    *out-- = (uint8_t)(number & 0xFF);
+    number >>= 8;
+  } while(number);
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, BER_DATA_TYPE_INTEGER);
+
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_unsigned_integer(unsigned char *out, uint32_t *out_len, uint8_t type, uint32_t number)
+{
+  uint32_t original_out_len;
+
+  original_out_len = *out_len;
+  do {
+    (*out_len)++;
+    *out-- = (uint8_t)(number & 0xFF);
+    number >>= 8;
+  } while(number);
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, type);
+
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_string_len(unsigned char *out, uint32_t *out_len, const char *str, uint32_t length)
+{
+  uint32_t i;
+
+  str += length - 1;
+  for(i = 0; i < length; ++i) {
+    (*out_len)++;
+    *out-- = (uint8_t)*str--;
+  }
+
+  out = snmp_ber_encode_length(out, out_len, length);
+  out = snmp_ber_encode_type(out, out_len, BER_DATA_TYPE_OCTET_STRING);
+
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_encode_null(unsigned char *out, uint32_t *out_len, uint8_t type)
+{
+  (*out_len)++;
+  *out-- = 0x00;
+  out = snmp_ber_encode_type(out, out_len, type);
+
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_type(unsigned char *buff, uint32_t *buff_len, uint8_t *type)
+{
+  *type = *buff++;
+  (*buff_len)--;
+
+  return buff;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_length(unsigned char *buff, uint32_t *buff_len, uint8_t *length)
+{
+  *length = *buff++;
+  (*buff_len)--;
+
+  return buff;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_integer(unsigned char *buf, uint32_t *buff_len, uint32_t *num)
+{
+  uint8_t i, len, type;
+
+  buf = snmp_ber_decode_type(buf, buff_len, &type);
+
+  if(type != BER_DATA_TYPE_INTEGER) {
+    /*
+     * Sanity check
+     * Invalid type in buffer
+     */
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, buff_len, &len);
+
+  if(len > 4) {
+    /*
+     * Sanity check
+     * It will not fit in the uint32_t
+     */
+    return NULL;
+  }
+
+  *num = (uint32_t)(*buf++ & 0xFF);
+  (*buff_len)--;
+  for(i = 1; i < len; ++i) {
+    *num <<= 8;
+    *num |= (uint8_t)(*buf++ & 0xFF);
+    (*buff_len)--;
+  }
+
+  return buf;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_unsigned_integer(unsigned char *buf, uint32_t *buff_len, uint8_t expected_type, uint32_t *num)
+{
+  uint8_t i, len, type;
+
+  buf = snmp_ber_decode_type(buf, buff_len, &type);
+
+  if(type != expected_type) {
+    /*
+     * Sanity check
+     * Invalid type in buffer
+     */
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, buff_len, &len);
+
+  if(len > 4) {
+    /*
+     * Sanity check
+     * It will not fit in the uint32_t
+     */
+    return NULL;
+  }
+
+  *num = (uint32_t)(*buf++ & 0xFF);
+  (*buff_len)--;
+  for(i = 1; i < len; ++i) {
+    *num <<= 8;
+    *num |= (uint8_t)(*buf++ & 0xFF);
+    (*buff_len)--;
+  }
+
+  return buf;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_string_len_buffer(unsigned char *buf, uint32_t *buff_len, const char **str, uint32_t *length)
+{
+  uint8_t type, i, length_bytes;
+
+  buf = snmp_ber_decode_type(buf, buff_len, &type);
+
+  if(type != BER_DATA_TYPE_OCTET_STRING) {
+    /*
+     * Sanity check
+     * Invalid type in buffer
+     */
+    return NULL;
+  }
+
+  if((*buf & 0x80) == 0) {
+    *length = (uint32_t)*buf++;
+    (*buff_len)--;
+  } else {
+
+    length_bytes = (uint8_t)(*buf++ & 0x7F);
+    (*buff_len)--;
+    if(length_bytes > 4) {
+      /*
+       * Sanity check
+       * It will not fit in the uint32_t
+       */
+      return NULL;
+    }
+
+    *length = (uint32_t)*buf++;
+    (*buff_len)--;
+    for(i = 1; i < length_bytes; ++i) {
+      *length <<= 8;
+      *length |= *buf++;
+      (*buff_len)--;
+    }
+  }
+
+  *str = (const char *)buf;
+  *buff_len -= *length;
+
+  return buf + *length;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_ber_decode_null(unsigned char *buf, uint32_t *buff_len)
+{
+  buf++;
+  (*buff_len)--;
+
+  buf++;
+  (*buff_len)--;
+
+  return buf;
+}
+/*---------------------------------------------------------------------------*/

os/net/app-layer/snmp/snmp-ber.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_BER_H_
+#define SNMP_BER_H_
+
+#define BER_DATA_TYPE_INTEGER           0x02
+#define BER_DATA_TYPE_OCTET_STRING      0x04
+#define BER_DATA_TYPE_NULL              0x05
+#define BER_DATA_TYPE_OID               0x06
+#define BER_DATA_TYPE_SEQUENCE          0x30
+
+/**
+ * @brief Encodes a type
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param type A type
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_type(unsigned char *out, uint32_t *out_len, uint8_t type);
+
+/**
+ * @brief Encodes the length
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param length A length
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_length(unsigned char *out, uint32_t *out_len, uint8_t length);
+
+/**
+ * @brief Encodes an integer
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param integer A integer
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_integer(unsigned char *out, uint32_t *out_len, uint32_t integer);
+
+/**
+ * @brief Encodes an unsigned integer
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param type A type that represents an unsigned integer
+ * @param number A number
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_unsigned_integer(unsigned char *out, uint32_t *out_len, uint8_t type, uint32_t number);
+
+/**
+ * @brief Encodes a string
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param str A string
+ * @param length The string length
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_string_len(unsigned char *out, uint32_t *out_len, const char *str, uint32_t length);
+
+/**
+ * @brief Encodes a null
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param type A type
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_ber_encode_null(unsigned char *out, uint32_t *out_len, uint8_t type);
+
+/**
+ * @brief Decodes a type
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ * @param type A pointer to the type
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_type(unsigned char *buff, uint32_t *buff_len, uint8_t *type);
+
+/**
+ * @brief Decodes a length
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ * @param length A pointer to the length
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_length(unsigned char *buff, uint32_t *buff_len, uint8_t *length);
+
+/**
+ * @brief Decodes an integer
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ * @param integer A pointer to the integer
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_integer(unsigned char *buff, uint32_t *buff_len, uint32_t *integer);
+
+/**
+ * @brief Decodes an unsigned number
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ * @param expected_type The expected type that represents an unsingned integer
+ * @param number A pointer to the number
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_unsigned_integer(unsigned char *buff, uint32_t *buff_len, uint8_t expected_type, uint32_t *number);
+
+/**
+ * @brief Decodes a string
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ * @param str A pointer to the string
+ * @param length A pointer to the string length
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_string_len_buffer(unsigned char *buff, uint32_t *buff_len, const char **str, uint32_t *length);
+
+/**
+ * @brief Decodes a null
+ *
+ * @param buff A pointer to the beginning of the buffer
+ * @param buff_len A pointer to the buffer length
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_ber_decode_null(unsigned char *buff, uint32_t *buff_len);
+
+#endif /* SNMP_BER_H_ */
+/** @} */

os/net/app-layer/snmp/snmp-conf.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      SNMP Configurable Macros
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_CONF_H_
+#define SNMP_CONF_H_
+
+/**
+ * \defgroup SNMPConfs SNMP Configurable Defines
+ * @{
+ */
+
+#ifdef SNMP_CONF_COMMUNITY
+/**
+ * \brief Configurable SNMP Community
+ */
+#define SNMP_COMMUNITY SNMP_CONF_COMMUNITY
+#else
+/**
+ * \brief Default SNMP Community
+ */
+#define SNMP_COMMUNITY "public"
+#endif
+
+#ifdef SNMP_CONF_MSG_OID_MAX_LEN
+/**
+ * \brief Configurable maximum number of IDs in one OID
+ */
+#define SNMP_MSG_OID_MAX_LEN SNMP_CONF_MSG_OID_MAX_LEN
+#else
+/**
+ * \brief Default maximum number of IDs in one OID
+ */
+#define SNMP_MSG_OID_MAX_LEN 16
+#endif
+
+#ifdef SNMP_CONF_MAX_NR_VALUES
+/**
+ * \brief Configurable maximum number of OIDs in one response
+ */
+#define SNMP_MAX_NR_VALUES SNMP_CONF_MAX_NR_VALUES
+#else
+/**
+ * \brief Default maximum number of OIDs in one response
+ */
+#define SNMP_MAX_NR_VALUES 2
+#endif
+
+#ifdef SNMP_CONF_MAX_PACKET_SIZE
+/**
+ * \brief Configurable maximum size of the packet in bytes
+ */
+#define SNMP_MAX_PACKET_SIZE SNMP_CONF_MAX_PACKET_SIZE
+#else
+/**
+ * \brief Default maximum size of the packet in bytes
+ */
+#define SNMP_MAX_PACKET_SIZE 512
+#endif
+
+#ifdef SNMP_CONF_PORT
+/**
+ * \brief Configurable SNMP port
+ */
+#define SNMP_PORT SNMP_CONF_PORT
+#else
+/**
+ * \brief Default SNMP port
+ */
+#define SNMP_PORT 161
+#endif
+
+/*@}*/
+
+#endif /* SNMP_CONF_H_ */
+/** @} */

os/net/app-layer/snmp/snmp-engine.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp-engine.h"
+#include "snmp-message.h"
+#include "snmp-mib.h"
+#include "snmp-oid.h"
+
+#define LOG_MODULE "SNMP [engine]"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+/*---------------------------------------------------------------------------*/
+int
+snmp_engine_get(snmp_header_t *header, snmp_varbind_t *varbinds, uint32_t varbinds_length)
+{
+  snmp_mib_resource_t *resource;
+  uint32_t i;
+
+  for(i = 0; i < varbinds_length; i++) {
+    resource = snmp_mib_find(varbinds[i].oid);
+    if(!resource) {
+      switch(header->version) {
+      case SNMP_VERSION_1:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        /*
+         * Varbinds are 1 indexed
+         */
+        header->error_index_max_repetitions.error_index = i + 1;
+        break;
+      case SNMP_VERSION_2C:
+        (&varbinds[i])->value_type = SNMP_DATA_TYPE_NO_SUCH_INSTANCE;
+        break;
+      default:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        header->error_index_max_repetitions.error_index = 0;
+      }
+    } else {
+      resource->handler(&varbinds[i], resource->oid);
+    }
+  }
+
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+int
+snmp_engine_get_next(snmp_header_t *header, snmp_varbind_t *varbinds, uint32_t varbinds_length)
+{
+  snmp_mib_resource_t *resource;
+  uint32_t i;
+
+  for(i = 0; i < varbinds_length; i++) {
+    resource = snmp_mib_find_next(varbinds[i].oid);
+    if(!resource) {
+      switch(header->version) {
+      case SNMP_VERSION_1:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        /*
+         * Varbinds are 1 indexed
+         */
+        header->error_index_max_repetitions.error_index = i + 1;
+        break;
+      case SNMP_VERSION_2C:
+        (&varbinds[i])->value_type = SNMP_DATA_TYPE_END_OF_MIB_VIEW;
+        break;
+      default:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        header->error_index_max_repetitions.error_index = 0;
+      }
+    } else {
+      resource->handler(&varbinds[i], resource->oid);
+    }
+  }
+
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+int
+snmp_engine_get_bulk(snmp_header_t *header, snmp_varbind_t *varbinds, uint32_t *varbinds_length)
+{
+  snmp_mib_resource_t *resource;
+  uint32_t i, j, original_varbinds_length;
+  uint32_t oid[SNMP_MAX_NR_VALUES][SNMP_MSG_OID_MAX_LEN];
+  uint8_t repeater;
+
+  /*
+   * A local copy of the requested oids must be kept since
+   *  the varbinds are modified on the fly
+   */
+  original_varbinds_length = *varbinds_length;
+  for(i = 0; i < original_varbinds_length; i++) {
+    snmp_oid_copy(oid[i], varbinds[i].oid);
+  }
+
+  *varbinds_length = 0;
+  for(i = 0; i < original_varbinds_length; i++) {
+    if(i >= header->error_status_non_repeaters.non_repeaters) {
+      break;
+    }
+
+    resource = snmp_mib_find_next(oid[i]);
+    if(!resource) {
+      switch(header->version) {
+      case SNMP_VERSION_1:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        /*
+         * Varbinds are 1 indexed
+         */
+        header->error_index_max_repetitions.error_index = i + 1;
+        break;
+      case SNMP_VERSION_2C:
+        (&varbinds[i])->value_type = SNMP_DATA_TYPE_END_OF_MIB_VIEW;
+        break;
+      default:
+        header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+        header->error_index_max_repetitions.error_index = 0;
+      }
+    } else {
+      if(*varbinds_length < SNMP_MAX_NR_VALUES) {
+        resource->handler(&varbinds[*varbinds_length], resource->oid);
+        (*varbinds_length)++;
+      }
+    }
+  }
+
+  for(i = 0; i < header->error_index_max_repetitions.max_repetitions; i++) {
+    repeater = 0;
+    for(j = header->error_status_non_repeaters.non_repeaters; j < original_varbinds_length; j++) {
+      resource = snmp_mib_find_next(oid[j]);
+      if(!resource) {
+        switch(header->version) {
+        case SNMP_VERSION_1:
+          header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+          /*
+           * Varbinds are 1 indexed
+           */
+          header->error_index_max_repetitions.error_index = *varbinds_length + 1;
+          break;
+        case SNMP_VERSION_2C:
+          if(*varbinds_length < SNMP_MAX_NR_VALUES) {
+            (&varbinds[*varbinds_length])->value_type = SNMP_DATA_TYPE_END_OF_MIB_VIEW;
+            snmp_oid_copy((&varbinds[*varbinds_length])->oid, oid[j]);
+            (*varbinds_length)++;
+          }
+          break;
+        default:
+          header->error_status_non_repeaters.error_status = SNMP_STATUS_NO_SUCH_NAME;
+          header->error_index_max_repetitions.error_index = 0;
+        }
+      } else {
+        if(*varbinds_length < SNMP_MAX_NR_VALUES) {
+          resource->handler(&varbinds[*varbinds_length], resource->oid);
+          (*varbinds_length)++;
+          snmp_oid_copy(oid[j], resource->oid);
+          repeater++;
+        }
+      }
+    }
+    if(repeater == 0) {
+      break;
+    }
+  }
+
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_engine(unsigned char *buff, uint32_t buff_len, unsigned char *out, uint32_t *out_len)
+{
+  static snmp_header_t header;
+  static snmp_varbind_t varbinds[SNMP_MAX_NR_VALUES];
+  static uint32_t varbind_length;
+
+  buff = snmp_message_decode(buff, buff_len, &header, varbinds, &varbind_length);
+  if(buff == NULL) {
+    return NULL;
+  }
+
+  if(header.version != SNMP_VERSION_1) {
+    if(strncmp(header.community.community, SNMP_COMMUNITY, header.community.length)) {
+      LOG_ERR("Request with invalid community\n");
+      return NULL;
+    }
+  }
+
+  /*
+   * Now handle the SNMP requests depending on their type
+   */
+  switch(header.pdu_type) {
+  case SNMP_DATA_TYPE_PDU_GET_REQUEST:
+    if(snmp_engine_get(&header, varbinds, varbind_length) == -1) {
+      return NULL;
+    }
+    break;
+
+  case SNMP_DATA_TYPE_PDU_GET_NEXT_REQUEST:
+    if(snmp_engine_get_next(&header, varbinds, varbind_length) == -1) {
+      return NULL;
+    }
+    break;
+
+  case SNMP_DATA_TYPE_PDU_GET_BULK:
+    if(snmp_engine_get_bulk(&header, varbinds, &varbind_length) == -1) {
+      return NULL;
+    }
+    break;
+
+  default:
+    LOG_ERR("Invalid request type");
+    return NULL;
+  }
+
+  header.pdu_type = SNMP_DATA_TYPE_PDU_GET_RESPONSE;
+  out = snmp_message_encode(out, out_len, &header, varbinds, varbind_length);
+
+  return ++out;
+}

os/net/app-layer/snmp/snmp-engine.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_ENGINE_H_
+#define SNMP_ENGINE_H_
+
+#include "snmp.h"
+
+/**
+ * @brief Process the SNMP packet and prepares the response
+ *
+ * @param buff A pointer to the beginning of the packet buffer
+ * @param buff_len The packet length
+ * @param out A pointer to the end of the response buffer
+ * @param out_len A pointer to the length of the response buffer
+ *
+ * @return NULL in case of fail or the first element in the response buffer
+ */
+unsigned char *
+snmp_engine(unsigned char *buff, uint32_t buff_len, unsigned char *out, uint32_t *out_len);
+
+#endif /* SNMP_ENGINE_H_ */
+
+/** @} */

os/net/app-layer/snmp/snmp-message.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp-message.h"
+#include "snmp-ber.h"
+#include "snmp-oid.h"
+
+#define LOG_MODULE "SNMP [message]"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+unsigned char *
+snmp_message_encode(unsigned char *out, uint32_t *out_len, snmp_header_t *header,
+                    snmp_varbind_t *varbinds, uint32_t varbind_num)
+{
+  snmp_varbind_t *varbind;
+  uint32_t original_out_len, last_out_len;
+  int8_t i;
+
+  original_out_len = *out_len;
+  for(i = varbind_num - 1; i >= 0; i--) {
+    varbind = &varbinds[i];
+
+    last_out_len = *out_len;
+
+    switch(varbind->value_type) {
+    case BER_DATA_TYPE_INTEGER:
+      out = snmp_ber_encode_integer(out, out_len, varbind->value.integer);
+      break;
+    case SNMP_DATA_TYPE_TIME_TICKS:
+      out = snmp_ber_encode_unsigned_integer(out, out_len, varbind->value_type, varbind->value.integer);
+      break;
+    case BER_DATA_TYPE_OCTET_STRING:
+      out = snmp_ber_encode_string_len(out, out_len, varbind->value.string.string, varbind->value.string.length);
+      break;
+    case BER_DATA_TYPE_OID:
+      out = snmp_oid_encode_oid(out, out_len, varbind->value.oid);
+      break;
+    case BER_DATA_TYPE_NULL:
+    case SNMP_DATA_TYPE_NO_SUCH_INSTANCE:
+    case SNMP_DATA_TYPE_END_OF_MIB_VIEW:
+      out = snmp_ber_encode_null(out, out_len, varbind->value_type);
+      break;
+    default:
+      return NULL;
+    }
+
+    out = snmp_oid_encode_oid(out, out_len, varbind->oid);
+    out = snmp_ber_encode_length(out, out_len, ((*out_len - last_out_len) & 0xFF));
+    out = snmp_ber_encode_type(out, out_len, BER_DATA_TYPE_SEQUENCE);
+  }
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, BER_DATA_TYPE_SEQUENCE);
+
+  if(header->pdu_type == SNMP_DATA_TYPE_PDU_GET_BULK) {
+    out = snmp_ber_encode_integer(out, out_len, header->error_index_max_repetitions.max_repetitions);
+    out = snmp_ber_encode_integer(out, out_len, header->error_status_non_repeaters.non_repeaters);
+  } else {
+    out = snmp_ber_encode_integer(out, out_len, header->error_index_max_repetitions.error_index);
+    out = snmp_ber_encode_integer(out, out_len, header->error_status_non_repeaters.error_status);
+  }
+  out = snmp_ber_encode_integer(out, out_len, header->request_id);
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, header->pdu_type);
+
+  out = snmp_ber_encode_string_len(out, out_len, header->community.community, header->community.length);
+  out = snmp_ber_encode_integer(out, out_len, header->version);
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, BER_DATA_TYPE_SEQUENCE);
+
+  return out;
+}
+uint8_t *
+snmp_message_decode(uint8_t *buf, uint32_t buf_len, snmp_header_t *header,
+                    snmp_varbind_t *varbinds, uint32_t *varbind_num)
+{
+  uint8_t type, len;
+  uint32_t i, oid_len;
+
+  buf = snmp_ber_decode_type(buf, &buf_len, &type);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode type\n");
+    return NULL;
+  }
+
+  if(type != BER_DATA_TYPE_SEQUENCE) {
+    LOG_DBG("Invalid type\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, &buf_len, &len);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode length\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_integer(buf, &buf_len, &header->version);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode version\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_string_len_buffer(buf, &buf_len, &header->community.community, &header->community.length);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode community\n");
+    return NULL;
+  }
+
+  if(header->version != SNMP_VERSION_1 &&
+     header->version != SNMP_VERSION_2C) {
+    LOG_DBG("Invalid version\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_type(buf, &buf_len, &type);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode type\n");
+    return NULL;
+  }
+
+  header->pdu_type = type;
+  if(header->pdu_type != SNMP_DATA_TYPE_PDU_GET_REQUEST &&
+     header->pdu_type != SNMP_DATA_TYPE_PDU_GET_NEXT_REQUEST &&
+     header->pdu_type != SNMP_DATA_TYPE_PDU_GET_RESPONSE &&
+     header->pdu_type != SNMP_DATA_TYPE_PDU_SET_REQUEST &&
+     header->pdu_type != SNMP_DATA_TYPE_PDU_GET_BULK) {
+    LOG_DBG("Invalid pdu type\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, &buf_len, &len);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode length\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_integer(buf, &buf_len, &header->request_id);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode request id\n");
+    return NULL;
+  }
+
+  if(header->pdu_type == SNMP_DATA_TYPE_PDU_GET_BULK) {
+    buf = snmp_ber_decode_integer(buf, &buf_len, &header->error_status_non_repeaters.non_repeaters);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode error status\n");
+      return NULL;
+    }
+
+    buf = snmp_ber_decode_integer(buf, &buf_len, &header->error_index_max_repetitions.max_repetitions);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode error index\n");
+      return NULL;
+    }
+  } else {
+    buf = snmp_ber_decode_integer(buf, &buf_len, &header->error_status_non_repeaters.error_status);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode error status\n");
+      return NULL;
+    }
+
+    buf = snmp_ber_decode_integer(buf, &buf_len, &header->error_index_max_repetitions.error_index);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode error index\n");
+      return NULL;
+    }
+  }
+
+  buf = snmp_ber_decode_type(buf, &buf_len, &type);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode type\n");
+    return NULL;
+  }
+
+  if(type != BER_DATA_TYPE_SEQUENCE) {
+    LOG_DBG("Invalid type\n");
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, &buf_len, &len);
+  if(buf == NULL) {
+    LOG_DBG("Could not decode length\n");
+    return NULL;
+  }
+
+  for(i = 0; buf_len > 0; ++i) {
+
+    buf = snmp_ber_decode_type(buf, &buf_len, &type);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode type\n");
+      return NULL;
+    }
+
+    if(type != BER_DATA_TYPE_SEQUENCE) {
+      LOG_DBG("Invalid (%X) type\n", type);
+      return NULL;
+    }
+
+    buf = snmp_ber_decode_length(buf, &buf_len, &len);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode length\n");
+      return NULL;
+    }
+
+    buf = snmp_oid_decode_oid(buf, &buf_len, varbinds[i].oid, &oid_len);
+    if(buf == NULL) {
+      LOG_DBG("Could not decode oid\n");
+      return NULL;
+    }
+
+    varbinds[i].value_type = *buf;
+
+    switch(varbinds[i].value_type) {
+    case BER_DATA_TYPE_INTEGER:
+      buf = snmp_ber_decode_integer(buf, &buf_len, &varbinds[i].value.integer);
+      break;
+    case SNMP_DATA_TYPE_TIME_TICKS:
+      buf = snmp_ber_decode_unsigned_integer(buf, &buf_len, varbinds[i].value_type, &varbinds[i].value.integer);
+      break;
+    case BER_DATA_TYPE_OCTET_STRING:
+      buf = snmp_ber_decode_string_len_buffer(buf, &buf_len, &varbinds[i].value.string.string, &varbinds[i].value.string.length);
+      break;
+    case BER_DATA_TYPE_NULL:
+      buf = snmp_ber_decode_null(buf, &buf_len);
+      break;
+    default:
+      LOG_DBG("Invalid varbind type\n");
+      return NULL;
+    }
+
+    if(buf == NULL) {
+      LOG_DBG("Could varbind type\n");
+      return NULL;
+    }
+  }
+
+  *varbind_num = i;
+
+  return buf;
+}

os/net/app-layer/snmp/snmp-message.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_MESSAGE_H_
+#define SNMP_MESSAGE_H_
+
+#include "snmp.h"
+
+#define SNMP_DATA_TYPE_TIME_TICKS               0x43
+#define SNMP_DATA_TYPE_NO_SUCH_INSTANCE         0x81
+#define SNMP_DATA_TYPE_END_OF_MIB_VIEW          0x82
+
+#define SNMP_DATA_TYPE_PDU_GET_REQUEST          0xA0
+#define SNMP_DATA_TYPE_PDU_GET_NEXT_REQUEST     0xA1
+#define SNMP_DATA_TYPE_PDU_GET_RESPONSE         0xA2
+#define SNMP_DATA_TYPE_PDU_SET_REQUEST          0xA3
+#define SNMP_DATA_TYPE_PDU_TRAP                 0xA4
+#define SNMP_DATA_TYPE_PDU_GET_BULK             0xA5
+
+/**
+ * @brief Encodes a SNMP message
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param header The SNMP header struct
+ * @param varbinds The varbinds array
+ * @param varbinds_length The number of varbinds
+ *
+ * @return
+ */
+unsigned char *
+snmp_message_encode(unsigned char *out, uint32_t *out_len, snmp_header_t *header,
+                    snmp_varbind_t *varbinds, uint32_t varbinds_length);
+/**
+ * @brief
+ *
+ * @param buf A pointer to the beginning of the buffer
+ * @param buf_len A pointer to the buffer length
+ * @param header The SNMP header struct
+ * @param varbinds The varbinds array
+ * @param varbinds_length A pointer to the number of varbinds
+ *
+ * @return
+ */
+uint8_t *
+snmp_message_decode(uint8_t *buf, uint32_t buf_len, snmp_header_t *header,
+                    snmp_varbind_t *varbinds, uint32_t *varbinds_length);
+
+#endif /* SNMP_MESSAGE_H_ */
+
+/** @} */

os/net/app-layer/snmp/snmp-mib.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp-mib.h"
+#include "snmp-oid.h"
+#include "lib/list.h"
+
+#define LOG_MODULE "SNMP [mib]"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+LIST(snmp_mib);
+
+snmp_mib_resource_t *
+snmp_mib_find(uint32_t *oid)
+{
+  snmp_mib_resource_t *resource;
+
+  resource = NULL;
+  for(resource = list_head(snmp_mib);
+      resource; resource = resource->next) {
+
+    if(!snmp_oid_cmp_oid(oid, resource->oid)) {
+      return resource;
+    }
+  }
+
+  return NULL;
+}
+snmp_mib_resource_t *
+snmp_mib_find_next(uint32_t *oid)
+{
+  snmp_mib_resource_t *resource;
+
+  resource = NULL;
+  for(resource = list_head(snmp_mib);
+      resource; resource = resource->next) {
+
+    if(snmp_oid_cmp_oid(resource->oid, oid) > 0) {
+      return resource;
+    }
+  }
+
+  return NULL;
+}
+void
+snmp_mib_add(snmp_mib_resource_t *new_resource)
+{
+  snmp_mib_resource_t *resource;
+
+  for(resource = list_head(snmp_mib);
+      resource; resource = resource->next) {
+
+    if(snmp_oid_cmp_oid(resource->oid, new_resource->oid) > 0) {
+      break;
+    }
+  }
+  if(resource == NULL) {
+    list_add(snmp_mib, new_resource);
+  } else {
+    list_insert(snmp_mib, new_resource, resource);
+  }
+
+#if LOG_LEVEL == LOG_LEVEL_DBG
+  /*
+   * We print the entire resource table
+   */
+  LOG_DBG("Table after insert.\n");
+  for(resource = list_head(snmp_mib);
+      resource; resource = resource->next) {
+
+    snmp_oid_print(resource->oid);
+  }
+#endif /* LOG_LEVEL == LOG_LEVEL_DBG  */
+}
+void
+snmp_mib_init(void)
+{
+  list_init(snmp_mib);
+}

os/net/app-layer/snmp/snmp-mib.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_MIB_H_
+#define SNMP_MIB_H_
+
+#include "snmp.h"
+
+/**
+ * @brief The MIB resource handler typedef
+ *
+ * @param varbind The varbind that is being changed
+ * @param oid The oid from the resource
+ */
+typedef void (*snmp_mib_resource_handler_t)(snmp_varbind_t *varbind, uint32_t *oid);
+
+/**
+ * @brief The MIB Resource struct
+ */
+typedef struct snmp_mib_resource_s {
+  /**
+   * @brief A pointer to the next element in the linked list
+   *
+   * @remarks This MUST be the first element in the struct
+   */
+  struct snmp_mib_resource_s *next;
+  /**
+   * @brief A array that represents the OID
+   *
+   * @remarks This array is "null" terminated. In this case the -1 is used.
+   */
+  uint32_t *oid;
+  /**
+   * @brief The function handler that is called for this resource
+   */
+  snmp_mib_resource_handler_t handler;
+} snmp_mib_resource_t;
+
+/**
+ * @brief Finds the MIB Resource for this OID
+ *
+ * @param oid The OID
+ *
+ * @return In case of success a pointer to the resouce or NULL in case of fail
+ */
+snmp_mib_resource_t *
+snmp_mib_find(uint32_t *oid);
+
+/**
+ * @brief Finds the next MIB Resource after this OID
+ *
+ * @param oid The OID
+ *
+ * @return In case of success a pointer to the resouce or NULL in case of fail
+ */
+snmp_mib_resource_t *
+snmp_mib_find_next(uint32_t *oid);
+
+/**
+ * @brief Adds a resource into the linked list
+ *
+ * @param resource The resource
+ */
+void
+snmp_mib_add(snmp_mib_resource_t *resource);
+
+/**
+ * @brief Initialize the MIB resources list
+ */
+void
+snmp_mib_init(void);
+
+#endif /* SNMP_MIB_H_ */
+/** @} */

os/net/app-layer/snmp/snmp-oid.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp-oid.h"
+#include "snmp-ber.h"
+
+#define LOG_MODULE "SNMP [oid]"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+/*---------------------------------------------------------------------------*/
+int
+snmp_oid_cmp_oid(uint32_t *oid1, uint32_t *oid2)
+{
+  uint8_t i;
+
+  i = 0;
+  while(oid1[i] != ((uint32_t)-1) &&
+        oid2[i] != ((uint32_t)-1)) {
+    if(oid1[i] != oid2[i]) {
+      if(oid1[i] < oid2[i]) {
+        return -1;
+      }
+      return 1;
+    }
+    i++;
+  }
+
+  if(oid1[i] == ((uint32_t)-1) &&
+     oid2[i] != ((uint32_t)-1)) {
+    return -1;
+  }
+
+  if(oid1[i] != ((uint32_t)-1) &&
+     oid2[i] == ((uint32_t)-1)) {
+    return 1;
+  }
+
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
+unsigned char *
+snmp_oid_encode_oid(unsigned char *out, uint32_t *out_len, uint32_t *oid)
+{
+  uint32_t original_out_len;
+  uint32_t *oid_start = oid;
+  uint32_t num;
+
+  original_out_len = *out_len;
+  while(*oid != ((uint32_t)-1)) {
+    ++oid;
+  }
+  --oid;
+
+  while(oid != oid_start) {
+    num = *oid;
+    (*out_len)++;
+    *out-- = (uint8_t)(num & 0x7F);
+    num >>= 7;
+
+    while(num) {
+      (*out_len)++;
+      *out-- = (uint8_t)((num & 0x7F) | 0x80);
+      num >>= 7;
+    }
+    --oid;
+  }
+
+  num = *(out + 1) + 40 * *oid;
+  (*out_len)--;
+  out++;
+  (*out_len)++;
+  *out-- = (uint8_t)(num & 0x7F);
+  num >>= 7;
+
+  while(num) {
+    (*out_len)++;
+    *out-- = (uint8_t)((num & 0x7F) | 0x80);
+    num >>= 7;
+  }
+
+  out = snmp_ber_encode_length(out, out_len, ((*out_len - original_out_len) & 0xFF));
+  out = snmp_ber_encode_type(out, out_len, SNMP_DATA_TYPE_OBJECT);
+
+  return out;
+}
+/*---------------------------------------------------------------------------*/
+uint8_t *
+snmp_oid_decode_oid(uint8_t *buf, uint32_t *buff_len, uint32_t *oid, uint32_t *oid_len)
+{
+  uint32_t *start;
+  uint8_t *buf_end, type;
+  uint8_t len;
+  div_t first;
+
+  start = oid;
+
+  buf = snmp_ber_decode_type(buf, buff_len, &type);
+  if(buf == NULL) {
+    return NULL;
+  }
+
+  if(type != SNMP_DATA_TYPE_OBJECT) {
+    return NULL;
+  }
+
+  buf = snmp_ber_decode_length(buf, buff_len, &len);
+  if(buf == NULL) {
+    return NULL;
+  }
+
+  buf_end = buf + len;
+
+  (*buff_len)--;
+  first = div(*buf++, 40);
+  *oid++ = (uint32_t)first.quot;
+  *oid++ = (uint32_t)first.rem;
+
+  while(buf != buf_end) {
+    --(*oid_len);
+    if(*oid_len == 0) {
+      return NULL;
+    }
+
+    int i;
+
+    *oid = (uint32_t)(*buf & 0x7F);
+    for(i = 0; i < 4; i++) {
+      (*buff_len)--;
+      if((*buf++ & 0x80) == 0) {
+        break;
+      }
+
+      *oid <<= 7;
+      *oid |= (*buf & 0x7F);
+    }
+
+    ++oid;
+  }
+
+  *oid++ = ((uint32_t)-1);
+  *oid_len = (uint32_t)(oid - start);
+
+  return buf;
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_oid_copy(uint32_t *dst, uint32_t *src)
+{
+  uint8_t i;
+
+  i = 0;
+  while(src[i] != ((uint32_t)-1)) {
+    dst[i] = src[i];
+    i++;
+  }
+  /*
+   * Copy the "null" terminator
+   */
+  dst[i] = src[i];
+}
+/*---------------------------------------------------------------------------*/
+#if LOG_LEVEL == LOG_LEVEL_DBG
+void
+snmp_oid_print(uint32_t *oid)
+{
+  uint8_t i;
+
+  i = 0;
+  LOG_DBG("{");
+  while(oid[i] != ((uint32_t)-1)) {
+    LOG_DBG_("%lu", (unsigned long)oid[i]);
+    i++;
+    if(oid[i] != ((uint32_t)-1)) {
+      LOG_DBG_(".");
+    }
+  }
+  LOG_DBG_("}\n");
+}
+#endif /* LOG_LEVEL == LOG_LEVEL_DBG  */

os/net/app-layer/snmp/snmp-oid.h

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+/**
+ * \addtogroup snmp
+ * @{
+ */
+
+#ifndef SNMP_OID_H_
+#define SNMP_OID_H_
+
+#include "snmp.h"
+
+#define SNMP_DATA_TYPE_OBJECT                   0x06
+
+/**
+ * @brief Compares to oids
+ *
+ * @param oid1 First Oid
+ * @param oid2 Second Oid
+ *
+ * @return < 0 if oid1 < oid2, > 0 if oid1 > oid2 and 0 if they are equal
+ */
+int
+snmp_oid_cmp_oid(uint32_t *oid1, uint32_t *oid2);
+
+/**
+ * @brief Encodes a Oid
+ *
+ * @param out A pointer to the end of the buffer
+ * @param out_len A pointer to the buffer length
+ * @param oid The Oid
+ *
+ * @return NULL if error or the next entry in the buffer
+ */
+unsigned char *
+snmp_oid_encode_oid(unsigned char *out, uint32_t *out_len, uint32_t *oid);
+
+/**
+ * @brief Decodes a Oid
+ *
+ * @param buf A pointer to the beginning of the buffer
+ * @param buf_len A pointer to the buffer length
+ * @param oid A pointer to the oid array
+ * @param oid_len A pointer to the oid length
+ *
+ * @return NULL if error or the first entry after the oid in the buffer
+ */
+unsigned char *
+snmp_oid_decode_oid(unsigned char *buf, uint32_t *buf_len, uint32_t *oid, uint32_t *oid_len);
+
+/**
+ * @brief Copies a Oid
+ *
+ * @param dst A pointer to the destination array
+ * @param src A pointer to the source array
+ */
+void
+snmp_oid_copy(uint32_t *dst, uint32_t *src);
+
+#if LOG_LEVEL == LOG_LEVEL_DBG
+/**
+ * @brief Prints a oid
+ *
+ * @param oid A oid
+ */
+void
+snmp_oid_print(uint32_t *oid);
+#endif /* LOG_LEVEL == LOG_LEVEL_DBG */
+
+#endif /* SNMP_OID_H_ */
+/** @} */

os/net/app-layer/snmp/snmp.c

+/*
+ * Copyright (C) 2019 Yago Fontoura do Rosario <yago.rosario@hotmail.com.br>
+ * All rights reserved.
+ *
+ * Redistribution 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 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 copyright holder 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 IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE
+ * COPYRIGHT HOLDER OR 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.
+ */
+/*---------------------------------------------------------------------------*/
+
+/**
+ * \file
+ *      An implementation of the Simple Network Management Protocol (RFC 3411-3418)
+ * \author
+ *      Yago Fontoura do Rosario <yago.rosario@hotmail.com.br
+ */
+
+#include "contiki.h"
+
+#include "snmp.h"
+#include "snmp-mib.h"
+#include "snmp-engine.h"
+
+#define LOG_MODULE "SNMP"
+#define LOG_LEVEL LOG_LEVEL_SNMP
+
+/*---------------------------------------------------------------------------*/
+#define SNMP_SERVER_PORT UIP_HTONS(SNMP_PORT)
+PROCESS(snmp_process, "SNMP Process");
+
+static struct uip_udp_conn *snmp_udp_conn = NULL;
+
+/*---------------------------------------------------------------------------*/
+static void
+snmp_process_data(void)
+{
+  static unsigned char packet[SNMP_MAX_PACKET_SIZE];
+  unsigned char *packet_end;
+  static uint32_t packet_len;
+
+  packet_end = packet + sizeof(packet) - 1;
+  packet_len = 0;
+
+  LOG_DBG("receiving UDP datagram from [");
+  LOG_DBG_6ADDR(&UIP_IP_BUF->srcipaddr);
+  LOG_DBG_("]:%u", uip_ntohs(UIP_UDP_BUF->srcport));
+  LOG_DBG_(" Length: %u\n", uip_datalen());
+
+  /*
+   * Handle the request
+   */
+  if((packet_end = snmp_engine(uip_appdata, uip_datalen(), packet_end, &packet_len)) == NULL) {
+    LOG_DBG("Error while handling the request\n");
+  } else {
+    LOG_DBG("Sending response\n");
+    /*
+     * Send the response
+     */
+    uip_udp_packet_sendto(snmp_udp_conn, packet_end, packet_len, &UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport);
+  }
+}
+/*---------------------------------------------------------------------------*/
+void
+snmp_init()
+{
+  snmp_mib_init();
+  process_start(&snmp_process, NULL);
+}
+/*---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------*/
+PROCESS_THREAD(snmp_process, ev, data)
+{
+  PROCESS_BEGIN();
+
+  /* new connection with remote host */
+  snmp_udp_conn = udp_new(NULL, 0, NULL);
+  udp_bind(snmp_udp_conn, SNMP_SERVER_PORT);
+  LOG_DBG("Listening on port %u\n", uip_ntohs(snmp_udp_conn->lport));
+
+  while(1) {
+    PROCESS_YIELD();
+
+    if(ev == tcpip_event) {
+      if(uip_newdata()) {
+        snmp_process_data();
+      }
+    }
+  } /* while (1) */
+
+  PROCESS_END();
+}
+/*---------------------------------------------------------------------------*/