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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* icmp.c - convenience functions for translating ICMP and ICMPv6 packets.
*/
#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#include <netinet/icmp6.h>
#include <linux/icmp.h>
#include "logging.h"
#include "icmp.h"
/* function: icmp_guess_ttl
* Guesses the number of hops a received packet has traversed based on its TTL.
* ttl - the ttl of the received packet.
*/
uint8_t icmp_guess_ttl(uint8_t ttl) {
if (ttl > 128) {
return 255 - ttl;
} else if (ttl > 64) {
return 128 - ttl;
} else if (ttl > 32) {
return 64 - ttl;
} else {
return 32 - ttl;
}
}
/* function: is_icmp_error
* Determines whether an ICMP type is an error message.
* type: the ICMP type
*/
int is_icmp_error(uint8_t type) {
return type == 3 || type == 11 || type == 12;
}
/* function: is_icmp6_error
* Determines whether an ICMPv6 type is an error message.
* type: the ICMPv6 type
*/
int is_icmp6_error(uint8_t type) {
return type < 128;
}
/* function: icmp_to_icmp6_type
* Maps ICMP types to ICMPv6 types. Partial implementation of RFC 6145, section 4.2.
* type - the ICMPv6 type
*/
uint8_t icmp_to_icmp6_type(uint8_t type, uint8_t code) {
switch (type) {
case ICMP_ECHO:
return ICMP6_ECHO_REQUEST;
case ICMP_ECHOREPLY:
return ICMP6_ECHO_REPLY;
case ICMP_TIME_EXCEEDED:
return ICMP6_TIME_EXCEEDED;
case ICMP_DEST_UNREACH:
// These two types need special translation which we don't support yet.
if (code != ICMP_UNREACH_PROTOCOL && code != ICMP_UNREACH_NEEDFRAG) {
return ICMP6_DST_UNREACH;
}
}
// We don't understand this ICMP type. Return parameter problem so the caller will bail out.
logmsg_dbg(ANDROID_LOG_DEBUG, "icmp_to_icmp6_type: unhandled ICMP type %d", type);
return ICMP6_PARAM_PROB;
}
/* function: icmp_to_icmp6_code
* Maps ICMP codes to ICMPv6 codes. Partial implementation of RFC 6145, section 4.2.
* type - the ICMP type
* code - the ICMP code
*/
uint8_t icmp_to_icmp6_code(uint8_t type, uint8_t code) {
switch (type) {
case ICMP_ECHO:
case ICMP_ECHOREPLY:
return 0;
case ICMP_TIME_EXCEEDED:
return code;
case ICMP_DEST_UNREACH:
switch (code) {
case ICMP_UNREACH_NET:
case ICMP_UNREACH_HOST:
return ICMP6_DST_UNREACH_NOROUTE;
case ICMP_UNREACH_PORT:
return ICMP6_DST_UNREACH_NOPORT;
case ICMP_UNREACH_NET_PROHIB:
case ICMP_UNREACH_HOST_PROHIB:
case ICMP_UNREACH_FILTER_PROHIB:
case ICMP_UNREACH_PRECEDENCE_CUTOFF:
return ICMP6_DST_UNREACH_ADMIN;
// Otherwise, we don't understand this ICMP type/code combination. Fall through.
}
}
logmsg_dbg(ANDROID_LOG_DEBUG, "icmp_to_icmp6_code: unhandled ICMP type/code %d/%d", type, code);
return 0;
}
/* function: icmp6_to_icmp_type
* Maps ICMPv6 types to ICMP types. Partial implementation of RFC 6145, section 5.2.
* type - the ICMP type
*/
uint8_t icmp6_to_icmp_type(uint8_t type, uint8_t code) {
switch (type) {
case ICMP6_ECHO_REQUEST:
return ICMP_ECHO;
case ICMP6_ECHO_REPLY:
return ICMP_ECHOREPLY;
case ICMP6_DST_UNREACH:
return ICMP_DEST_UNREACH;
case ICMP6_TIME_EXCEEDED:
return ICMP_TIME_EXCEEDED;
}
// We don't understand this ICMP type. Return parameter problem so the caller will bail out.
logmsg_dbg(ANDROID_LOG_DEBUG, "icmp6_to_icmp_type: unhandled ICMP type/code %d/%d", type, code);
return ICMP_PARAMETERPROB;
}
/* function: icmp6_to_icmp_code
* Maps ICMPv6 codes to ICMP codes. Partial implementation of RFC 6145, section 5.2.
* type - the ICMPv6 type
* code - the ICMPv6 code
*/
uint8_t icmp6_to_icmp_code(uint8_t type, uint8_t code) {
switch (type) {
case ICMP6_ECHO_REQUEST:
case ICMP6_ECHO_REPLY:
case ICMP6_TIME_EXCEEDED:
return code;
case ICMP6_DST_UNREACH:
switch (code) {
case ICMP6_DST_UNREACH_NOROUTE:
return ICMP_UNREACH_HOST;
case ICMP6_DST_UNREACH_ADMIN:
return ICMP_UNREACH_HOST_PROHIB;
case ICMP6_DST_UNREACH_BEYONDSCOPE:
return ICMP_UNREACH_HOST;
case ICMP6_DST_UNREACH_ADDR:
return ICMP_HOST_UNREACH;
case ICMP6_DST_UNREACH_NOPORT:
return ICMP_UNREACH_PORT;
// Otherwise, we don't understand this ICMPv6 type/code combination. Fall through.
}
}
logmsg_dbg(ANDROID_LOG_DEBUG, "icmp6_to_icmp_code: unhandled ICMP type/code %d/%d", type, code);
return 0;
}
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