/**
* Processes ICMP input packets, called from ip_input().
*
* Currently only processes icmp echo requests and sends
* out the echo response.
*
* @param p the icmp echo request packet, p->payload pointing to the icmp header
* @param inp the netif on which this packet was received
*/
void
icmp_input(struct pbuf *p, struct netif *inp)
{
u8_t type;
#ifdef LWIP_DEBUG
u8_t code;
#endif /* LWIP_DEBUG */
struct icmp_echo_hdr *iecho;
struct ip_hdr *iphdr;
s16_t hlen;
ICMP_STATS_INC(icmp.recv);
snmp_inc_icmpinmsgs();
iphdr = (struct ip_hdr *)ip_current_header();
hlen = IPH_HL(iphdr) * 4;
if (p->len < sizeof(u16_t)*2) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
goto lenerr;
}
type = *((u8_t *)p->payload);
#ifdef LWIP_DEBUG
code = *(((u8_t *)p->payload)+1);
#endif /* LWIP_DEBUG */
switch (type) {
case ICMP_ER:
/* This is OK, echo reply might have been parsed by a raw PCB
(as obviously, an echo request has been sent, too). */
break;
case ICMP_ECHO:
#if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
{
int accepted = 1;
#if !LWIP_MULTICAST_PING
/* multicast destination address? */
if (ip_addr_ismulticast(ip_current_dest_addr())) {
accepted = 0;
}
#endif /* LWIP_MULTICAST_PING */
#if !LWIP_BROADCAST_PING
/* broadcast destination address? */
if (ip_addr_isbroadcast(ip_current_dest_addr(), inp)) {
accepted = 0;
}
#endif /* LWIP_BROADCAST_PING */
/* broadcast or multicast destination address not acceptd? */
if (!accepted) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
ICMP_STATS_INC(icmp.err);
pbuf_free(p);
return;
}
}
#endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
goto lenerr;
}
#if CHECKSUM_CHECK_ICMP
if (inet_chksum_pbuf(p) != 0) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
pbuf_free(p);
ICMP_STATS_INC(icmp.chkerr);
snmp_inc_icmpinerrors();
return;
}
#endif
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
/* p is not big enough to contain link headers
* allocate a new one and copy p into it
*/
struct pbuf *r;
/* switch p->payload to ip header */
if (pbuf_header(p, hlen)) {
LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
goto memerr;
}
/* allocate new packet buffer with space for link headers */
r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
if (r == NULL) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
goto memerr;
}
LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
(r->len >= hlen + sizeof(struct icmp_echo_hdr)));
/* copy the whole packet including ip header */
if (pbuf_copy(r, p) != ERR_OK) {
LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
goto memerr;
}
iphdr = (struct ip_hdr *)r->payload;
/* switch r->payload back to icmp header */
if (pbuf_header(r, -hlen)) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
/* free the original p */
pbuf_free(p);
/* we now have an identical copy of p that has room for link headers */
p = r;
} else {
/* restore p->payload to point to icmp header */
if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
}
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
/* At this point, all checks are OK. */
/* We generate an answer by switching the dest and src ip addresses,
* setting the icmp type to ECHO_RESPONSE and updating the checksum. */
iecho = (struct icmp_echo_hdr *)p->payload;
ip_addr_copy(iphdr->src, *ip_current_dest_addr());
ip_addr_copy(iphdr->dest, *ip_current_src_addr());
ICMPH_TYPE_SET(iecho, ICMP_ER);
#if CHECKSUM_GEN_ICMP
/* adjust the checksum */
if (iecho->chksum > PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
} else {
iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
}
#else /* CHECKSUM_GEN_ICMP */
iecho->chksum = 0;
#endif /* CHECKSUM_GEN_ICMP */
/* Set the correct TTL and recalculate the header checksum. */
IPH_TTL_SET(iphdr, ICMP_TTL);
IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
#endif /* CHECKSUM_GEN_IP */
ICMP_STATS_INC(icmp.xmit);
/* increase number of messages attempted to send */
snmp_inc_icmpoutmsgs();
/* increase number of echo replies attempted to send */
snmp_inc_icmpoutechoreps();
if(pbuf_header(p, hlen)) {
LWIP_ASSERT("Can't move over header in packet", 0);
} else {
err_t ret;
/* send an ICMP packet, src addr is the dest addr of the curren packet */
ret = ip_output_if(p, ip_current_dest_addr(), IP_HDRINCL,
ICMP_TTL, 0, IP_PROTO_ICMP, inp);
if (ret != ERR_OK) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
}
}
break;
default:
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
(s16_t)type, (s16_t)code));
ICMP_STATS_INC(icmp.proterr);
ICMP_STATS_INC(icmp.drop);
}
pbuf_free(p);
return;
lenerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.lenerr);
snmp_inc_icmpinerrors();
return;
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
memerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.err);
snmp_inc_icmpinerrors();
return;
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
}
/**
* Proxy ICMP input packets, called from ip_input().
*
* @param p the icmp echo request packet, p->payload pointing to the icmp header
* @param inp the netif on which this packet was received
*/
void
icmp_proxy_input(struct pbuf *p, struct netif *inp)
{
u8_t type, code;
# ifdef VBOX
(void)inp;
# endif
ICMP_STATS_INC(icmp.recv);
snmp_inc_icmpinmsgs();
if (p->tot_len < 4) { /* type(1), code(1), checksum(2) */
LWIP_DEBUGF(ICMP_DEBUG,
("icmp_proxy_input: short ICMP (%"U16_F" bytes) received\n",
p->tot_len));
goto lenerr;
}
if (inet_chksum_pbuf(p) != 0) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_proxy_input: bad checksum\n"));
pbuf_free(p);
ICMP_STATS_INC(icmp.chkerr);
snmp_inc_icmpinerrors();
return;
}
type = *((u8_t *)p->payload);
code = *(((u8_t *)p->payload)+1);
switch (type) {
case ICMP_ER:
/* ignore silently */
pbuf_free(p);
break;
case ICMP_DUR:
/* TODO: anything useful we can do? */
pbuf_free(p);
break;
case ICMP_ECHO:
if (code != 0) {
goto proterr;
}
if (p->tot_len < 8) {
goto lenerr;
}
if (ping_proxy_accept_callback != NULL) {
(*ping_proxy_accept_callback)(ping_proxy_accept_arg, p);
}
break;
default:
goto proterr;
}
return;
lenerr:
ICMP_STATS_INC(icmp.lenerr);
goto drop;
proterr:
LWIP_DEBUGF(ICMP_DEBUG,
("icmp_proxy_input: ICMP type %"S16_F" code %"S16_F
" not supported.\n",
(s16_t)type, (s16_t)code));
ICMP_STATS_INC(icmp.proterr);
goto drop;
drop:
pbuf_free(p);
ICMP_STATS_INC(icmp.drop);
snmp_inc_icmpinerrors();
return;
}
/* 调用途径：ethernetif_input() -> ethernet_input() -> ip_input() -> icmp_input()*/
void
icmp_input(struct pbuf *p, struct netif *inp)
{
u8_t type;
#ifdef LWIP_DEBUG
u8_t code;
#endif /* LWIP_DEBUG */
struct icmp_echo_hdr *iecho;
struct ip_hdr *iphdr;
/* IP 地址 */
struct ip_addr tmpaddr;
s16_t hlen;
ICMP_STATS_INC(icmp.recv);
snmp_inc_icmpinmsgs();
/* 指向IP首部 */
iphdr = p->payload;
/* 获得IP报头长度 */
hlen = IPH_HL(iphdr) * 4;
/* pbuf的payload向后移动到IP载荷，即ICMP报头处
* 如果IP的载荷小于4字节，则跳到lenerr处，释放pbuf
*/
if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
goto lenerr;
}
/* 获取ICMP报头中的类型 */
type = *((u8_t *)p->payload);
#ifdef LWIP_DEBUG
code = *(((u8_t *)p->payload)+1);
#endif /* LWIP_DEBUG */
switch (type) {
/* 如果ICMP类型是回显请求 */
case ICMP_ECHO:
/* 先检查目的IP地址是否合法 */
#if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
{
/* accepted表示是否对ICMP回显请求进行回应 */
int accepted = 1;
#if !LWIP_MULTICAST_PING
/* multicast destination address? */
/* 如果目的IP地址是多播地址，则不回应 */
if (ip_addr_ismulticast(&iphdr->dest)) {
accepted = 0;
}
#endif /* LWIP_MULTICAST_PING */
#if !LWIP_BROADCAST_PING
/* broadcast destination address? */
/* 如果目的IP地址是广播地址，则不回应 */
if (ip_addr_isbroadcast(&iphdr->dest, inp)) {
accepted = 0;
}
#endif /* LWIP_BROADCAST_PING */
/* broadcast or multicast destination address not acceptd? */
/* 如果不回应，则释放pbuf后，返回 */
if (!accepted) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
ICMP_STATS_INC(icmp.err);
pbuf_free(p);
return;
}
}
#endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
/* 检查ICMP报文长度是否合法,ICMP报文总长度不能小于ICMP报头长度8字节 */
if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
/* 跳到lenerr处执行返回操作 */
goto lenerr;
}
/* 计算ICMP的校验和是否正确 */
if (inet_chksum_pbuf(p) != 0) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
/* ICMP校验和错误，则释放pbuf，并返回 */
pbuf_free(p);
ICMP_STATS_INC(icmp.chkerr);
snmp_inc_icmpinerrors();
return;
}
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
/* p is not big enough to contain link headers
* allocate a new one and copy p into it
*/
struct pbuf *r;
/* switch p->payload to ip header */
if (pbuf_header(p, hlen)) {
LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
goto memerr;
}
/* allocate new packet buffer with space for link headers */
r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
if (r == NULL) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
goto memerr;
}
LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
(r->len >= hlen + sizeof(struct icmp_echo_hdr)));
/* copy the whole packet including ip header */
if (pbuf_copy(r, p) != ERR_OK) {
LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
goto memerr;
}
iphdr = r->payload;
/* switch r->payload back to icmp header */
if (pbuf_header(r, -hlen)) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
/* free the original p */
pbuf_free(p);
/* we now have an identical copy of p that has room for link headers */
p = r;
} else {
/* restore p->payload to point to icmp header */
if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
}
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
/* At this point, all checks are OK. */
/* We generate an answer by switching the dest and src ip addresses,
* setting the icmp type to ECHO_RESPONSE and updating the checksum. */
/* 校验完成，调整ICMP回显请求的相关字段，生成回显应答
* 交换IP数据报的源IP和目的IP地址，填写ICMP报文的类型字段，并重新计算ICMP的校验和
*/
/* 获取ICMP报头指针 */
iecho = p->payload;
/* 交换IP报头的源IP地址和目的IP地址 */
tmpaddr.addr = iphdr->src.addr;
iphdr->src.addr = iphdr->dest.addr;
iphdr->dest.addr = tmpaddr.addr;
/* 设置ICMP报文类型为回显应答 */
ICMPH_TYPE_SET(iecho, ICMP_ER);
/* adjust the checksum */
/* 调整ICMP的校验和 */
if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
iecho->chksum += htons(ICMP_ECHO << 8) + 1;
} else {
iecho->chksum += htons(ICMP_ECHO << 8);
}
/* Set the correct TTL and recalculate the header checksum. */
/* 设置IP首部的TTL */
IPH_TTL_SET(iphdr, ICMP_TTL);
/* 计算IP首部校验和 */
IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
#endif /* CHECKSUM_GEN_IP */
/* 注意：这里没有修改IP首部的标识字段，所以ICMP回显应答的IP首部的标识字段和
* ICMP回显请求的标识字段是相同的。理论上来说ICMP回显应答的IP首部标识字段应该
* 被修改，但为什么不修改？
* 对Linux主机进行ping，Linux主机回复的ICMP回显应答的IP首部的标识字段就修改了
*/
ICMP_STATS_INC(icmp.xmit);
/* increase number of messages attempted to send */
snmp_inc_icmpoutmsgs();
/* increase number of echo replies attempted to send */
snmp_inc_icmpoutechoreps();
/* pbuf的payload由ICMP的报头移动到IP的报头，hlen保存了IP报头的长度 */
if(pbuf_header(p, hlen)) {
LWIP_ASSERT("Can't move over header in packet", 0);
/* 移动失败 */
} else {
/* 移动成功 */
err_t ret;
/* 调用ip_output_if发送IP数据报，IP_HDRINCL表示IP首部已经填写好，并且
* pbuf的payload指向IP数据报首部，而不是IP载荷首部
*/
ret = ip_output_if(p, &(iphdr->src), IP_HDRINCL,
ICMP_TTL, 0, IP_PROTO_ICMP, inp);
if (ret != ERR_OK) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
}
}
break;
/* 如果ICMP类型不是ICMP回显请求，则直接忽略 */
default:
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
(s16_t)type, (s16_t)code));
/* 更新统计量 */
ICMP_STATS_INC(icmp.proterr);
ICMP_STATS_INC(icmp.drop);
}
/* 释放pbuf */
pbuf_free(p);
return;
lenerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.lenerr);
snmp_inc_icmpinerrors();
return;
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
memerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.err);
snmp_inc_icmpinerrors();
return;
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
}
/**
* Processes ICMP input packets, called from ip_input().
*
* Currently only processes icmp echo requests and sends
* out the echo response.
*
* @param p the icmp echo request packet, p->payload pointing to the ip header
* @param inp the netif on which this packet was received
*/
void
icmp_input(struct pbuf *p, struct netif *inp)
{
u8_t type;
#ifdef LWIP_DEBUG
u8_t code;
#endif /* LWIP_DEBUG */
struct icmp_echo_hdr *iecho;
struct ip_hdr *iphdr;
struct ip_addr tmpaddr;
s16_t hlen;
u8_t iptxt[20];
volatile u8_t iptab[4];
u32_t IPaddress;
ICMP_STATS_INC(icmp.recv);
snmp_inc_icmpinmsgs();
iphdr = p->payload;
hlen = IPH_HL(iphdr) * 4;
if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
goto lenerr;
}
IPaddress = iphdr->src.addr;
/* read its IP address */
iptab[0] = (u8_t)(IPaddress >> 24);
iptab[1] = (u8_t)(IPaddress >> 16);
iptab[2] = (u8_t)(IPaddress >> 8);
iptab[3] = (u8_t)(IPaddress);
sprintf((char*)iptxt, "Ping: %d.%d.%d.%d ", iptab[3], iptab[2], iptab[1], iptab[0]);
LCD_DisplayStringLine(Line4, iptxt);
printf("\n\r%s", iptxt);
type = *((u8_t *)p->payload);
#ifdef LWIP_DEBUG
code = *(((u8_t *)p->payload)+1);
#endif /* LWIP_DEBUG */
switch (type) {
case ICMP_ECHO:
#if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
{
int accepted = 1;
#if !LWIP_MULTICAST_PING
/* multicast destination address? */
if (ip_addr_ismulticast(&iphdr->dest)) {
accepted = 0;
}
#endif /* LWIP_MULTICAST_PING */
#if !LWIP_BROADCAST_PING
/* broadcast destination address? */
if (ip_addr_isbroadcast(&iphdr->dest, inp)) {
accepted = 0;
}
#endif /* LWIP_BROADCAST_PING */
/* broadcast or multicast destination address not acceptd? */
if (!accepted) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
ICMP_STATS_INC(icmp.err);
pbuf_free(p);
return;
}
}
#endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
goto lenerr;
}
if (inet_chksum_pbuf(p) != 0) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
pbuf_free(p);
ICMP_STATS_INC(icmp.chkerr);
snmp_inc_icmpinerrors();
return;
}
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
/* p is not big enough to contain link headers
* allocate a new one and copy p into it
*/
struct pbuf *r;
/* switch p->payload to ip header */
if (pbuf_header(p, hlen)) {
LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
goto memerr;
}
/* allocate new packet buffer with space for link headers */
r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
if (r == NULL) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
goto memerr;
}
LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
(r->len >= hlen + sizeof(struct icmp_echo_hdr)));
/* copy the whole packet including ip header */
if (pbuf_copy(r, p) != ERR_OK) {
LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
goto memerr;
}
iphdr = r->payload;
/* switch r->payload back to icmp header */
if (pbuf_header(r, -hlen)) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
/* free the original p */
pbuf_free(p);
/* we now have an identical copy of p that has room for link headers */
p = r;
} else {
/* restore p->payload to point to icmp header */
if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto memerr;
}
}
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
/* At this point, all checks are OK. */
/* We generate an answer by switching the dest and src ip addresses,
* setting the icmp type to ECHO_RESPONSE and updating the checksum. */
iecho = p->payload;
tmpaddr.addr = iphdr->src.addr;
iphdr->src.addr = iphdr->dest.addr;
iphdr->dest.addr = tmpaddr.addr;
ICMPH_TYPE_SET(iecho, ICMP_ER);
/* This part of code has been modified by ST's MCD Application Team */
/* To use the Checksum Offload Engine for the putgoing ICMP packets,
the ICMP checksum field should be set to 0, this is required only for Tx ICMP*/
#ifdef CHECKSUM_BY_HARDWARE
iecho->chksum = 0;
#else
/* adjust the checksum */
if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
iecho->chksum += htons(ICMP_ECHO << 8) + 1;
} else {
iecho->chksum += htons(ICMP_ECHO << 8);
}
#endif
/* Set the correct TTL and recalculate the header checksum. */
IPH_TTL_SET(iphdr, ICMP_TTL);
IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
#endif /* CHECKSUM_GEN_IP */
ICMP_STATS_INC(icmp.xmit);
/* increase number of messages attempted to send */
snmp_inc_icmpoutmsgs();
/* increase number of echo replies attempted to send */
snmp_inc_icmpoutechoreps();
if(pbuf_header(p, hlen)) {
LWIP_ASSERT("Can't move over header in packet", 0);
} else {
err_t ret;
ret = ip_output_if(p, &(iphdr->src), IP_HDRINCL,
ICMP_TTL, 0, IP_PROTO_ICMP, inp);
if (ret != ERR_OK) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
}
}
break;
default:
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
(s16_t)type, (s16_t)code));
ICMP_STATS_INC(icmp.proterr);
ICMP_STATS_INC(icmp.drop);
}
pbuf_free(p);
return;
lenerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.lenerr);
snmp_inc_icmpinerrors();
return;
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
memerr:
pbuf_free(p);
ICMP_STATS_INC(icmp.err);
snmp_inc_icmpinerrors();
return;
#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
}
void
icmp_input(struct pbuf *p, struct netif *inp)
{
u8_t type;
u8_t code;
struct icmp_echo_hdr *iecho;
struct ip_hdr *iphdr;
struct ip_addr tmpaddr;
u16_t hlen;
u8_t *payload = NULL;
ICMP_STATS_INC(icmp.recv);
snmp_inc_icmpinmsgs();
iphdr = p->payload;
hlen = IPH_HL(iphdr) * 4;
if (p->tot_len < sizeof(u16_t)*2) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
pbuf_free(p);
ICMP_STATS_INC(icmp.lenerr);
snmp_inc_icmpinerrors();
return;
}
payload = (u8_t *)p->payload + hlen;
type = *payload;
code = *(payload+1);
switch (type) {
case ICMP_ECHO:
/* broadcast or multicast destination address? */
if (ip_addr_isbroadcast(&iphdr->dest, inp) || ip_addr_ismulticast(&iphdr->dest)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
ICMP_STATS_INC(icmp.err);
pbuf_free(p);
return;
}
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
pbuf_free(p);
ICMP_STATS_INC(icmp.lenerr);
snmp_inc_icmpinerrors();
return;
}
iecho = (struct icmp_echo_hdr *)payload;
if (inet_chksum_pbuf(p) != 0) {
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
pbuf_free(p);
ICMP_STATS_INC(icmp.chkerr);
snmp_inc_icmpinerrors();
return;
}
tmpaddr.addr = iphdr->src.addr;
iphdr->src.addr = iphdr->dest.addr;
iphdr->dest.addr = tmpaddr.addr;
ICMPH_TYPE_SET(iecho, ICMP_ER);
/* adjust the checksum */
if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
iecho->chksum += htons(ICMP_ECHO << 8) + 1;
} else {
iecho->chksum += htons(ICMP_ECHO << 8);
}
ICMP_STATS_INC(icmp.xmit);
/* increase number of messages attempted to send */
snmp_inc_icmpoutmsgs();
/* increase number of echo replies attempted to send */
snmp_inc_icmpoutechoreps();
pbuf_header(p, hlen);
ip_output_if(p, &(iphdr->src), IP_HDRINCL,
IPH_TTL(iphdr), 0, IP_PROTO_ICMP, inp);
break;
default:
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n", (s16_t)type, (s16_t)code));
ICMP_STATS_INC(icmp.proterr);
ICMP_STATS_INC(icmp.drop);
}
pbuf_free(p);
}
