/**
* Process an incoming UDP datagram.
*
* Given an incoming UDP datagram (as a chain of pbufs) this function
* finds a corresponding UDP PCB and hands over the pbuf to the pcbs
* recv function. If no pcb is found or the datagram is incorrect, the
* pbuf is freed.
*
* @param p pbuf to be demultiplexed to a UDP PCB.
* @param inp network interface on which the datagram was received.
*
*/
void
udp_input(struct pbuf *p, struct netif *inp)
{
struct udp_hdr *udphdr;
struct udp_pcb *pcb, *prev;
struct udp_pcb *uncon_pcb;
struct ip_hdr *iphdr;
u16_t src, dest;
u8_t local_match;
u8_t broadcast;
PERF_START;
UDP_STATS_INC(udp.recv);
iphdr = (struct ip_hdr *)p->payload;
/* Check minimum length (IP header + UDP header)
* and move payload pointer to UDP header */
if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
/* drop short packets */
LWIP_DEBUGF(UDP_DEBUG,
("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
UDP_STATS_INC(udp.lenerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
udphdr = (struct udp_hdr *)p->payload;
/* is broadcast packet ? */
broadcast = ip_addr_isbroadcast(¤t_iphdr_dest, inp);
LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));
/* convert src and dest ports to host byte order */
src = ntohs(udphdr->src);
dest = ntohs(udphdr->dest);
udp_debug_print(udphdr);
/* print the UDP source and destination */
LWIP_DEBUGF(UDP_DEBUG,
("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
"(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
ip4_addr1_16(&iphdr->dest), ip4_addr2_16(&iphdr->dest),
ip4_addr3_16(&iphdr->dest), ip4_addr4_16(&iphdr->dest), ntohs(udphdr->dest),
ip4_addr1_16(&iphdr->src), ip4_addr2_16(&iphdr->src),
ip4_addr3_16(&iphdr->src), ip4_addr4_16(&iphdr->src), ntohs(udphdr->src)));
#if LWIP_DHCP
pcb = NULL;
/* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
if (dest == DHCP_CLIENT_PORT) {
/* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
if (src == DHCP_SERVER_PORT) {
if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
/* accept the packe if
(- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
- inp->dhcp->pcb->remote == ANY or iphdr->src */
if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), ¤t_iphdr_src))) {
pcb = inp->dhcp->pcb;
}
}
}
} else
#endif /* LWIP_DHCP */
{
prev = NULL;
local_match = 0;
uncon_pcb = NULL;
/* Iterate through the UDP pcb list for a matching pcb.
* 'Perfect match' pcbs (connected to the remote port & ip address) are
* preferred. If no perfect match is found, the first unconnected pcb that
* matches the local port and ip address gets the datagram. */
for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
local_match = 0;
/* print the PCB local and remote address */
LWIP_DEBUGF(UDP_DEBUG,
("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
"(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
ip4_addr1_16(&pcb->local_ip), ip4_addr2_16(&pcb->local_ip),
ip4_addr3_16(&pcb->local_ip), ip4_addr4_16(&pcb->local_ip), pcb->local_port,
ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip), pcb->remote_port));
/* compare PCB local addr+port to UDP destination addr+port */
if (pcb->local_port == dest) {
if (
(!broadcast && ip_addr_isany(&pcb->local_ip)) ||
ip_addr_cmp(&(pcb->local_ip), ¤t_iphdr_dest) ||
#if LWIP_IGMP
ip_addr_ismulticast(¤t_iphdr_dest) ||
#endif /* LWIP_IGMP */
#if IP_SOF_BROADCAST_RECV
(broadcast && ip_get_option(pcb, SOF_BROADCAST) &&
(ip_addr_isany(&pcb->local_ip) ||
ip_addr_netcmp(&pcb->local_ip, ip_current_dest_addr(), &inp->netmask)))) {
#else /* IP_SOF_BROADCAST_RECV */
(broadcast &&
(ip_addr_isany(&pcb->local_ip) ||
ip_addr_netcmp(&pcb->local_ip, ip_current_dest_addr(), &inp->netmask)))) {
#endif /* IP_SOF_BROADCAST_RECV */
local_match = 1;
if ((uncon_pcb == NULL) &&
((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
/* the first unconnected matching PCB */
uncon_pcb = pcb;
}
}
}
/* compare PCB remote addr+port to UDP source addr+port */
if ((local_match != 0) &&
(pcb->remote_port == src) &&
(ip_addr_isany(&pcb->remote_ip) ||
ip_addr_cmp(&(pcb->remote_ip), ¤t_iphdr_src))) {
/* the first fully matching PCB */
if (prev != NULL) {
/* move the pcb to the front of udp_pcbs so that is
found faster next time */
prev->next = pcb->next;
pcb->next = udp_pcbs;
udp_pcbs = pcb;
} else {
UDP_STATS_INC(udp.cachehit);
}
break;
}
prev = pcb;
}
/* no fully matching pcb found? then look for an unconnected pcb */
if (pcb == NULL) {
pcb = uncon_pcb;
}
}
/* Check checksum if this is a match or if it was directed at us. */
if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, ¤t_iphdr_dest)) {
LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
#if LWIP_UDPLITE
if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
/* Do the UDP Lite checksum */
#if CHECKSUM_CHECK_UDP
u16_t chklen = ntohs(udphdr->len);
if (chklen < sizeof(struct udp_hdr)) {
if (chklen == 0) {
/* For UDP-Lite, checksum length of 0 means checksum
over the complete packet (See RFC 3828 chap. 3.1) */
chklen = p->tot_len;
} else {
/* At least the UDP-Lite header must be covered by the
checksum! (Again, see RFC 3828 chap. 3.1) */
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
}
if (inet_chksum_pseudo_partial(p, ¤t_iphdr_src, ¤t_iphdr_dest,
IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
#endif /* CHECKSUM_CHECK_UDP */
} else
#endif /* LWIP_UDPLITE */
{
#if CHECKSUM_CHECK_UDP
if (udphdr->chksum != 0) {
if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
IP_PROTO_UDP, p->tot_len) != 0) {
LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
("udp_input: UDP datagram discarded due to failing checksum\n"));
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
}
#endif /* CHECKSUM_CHECK_UDP */
}
if(pbuf_header(p, -UDP_HLEN)) {
/* Can we cope with this failing? Just assert for now */
LWIP_ASSERT("pbuf_header failed\n", 0);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
if (pcb != NULL) {
snmp_inc_udpindatagrams();
#if SO_REUSE && SO_REUSE_RXTOALL
if ((broadcast || ip_addr_ismulticast(¤t_iphdr_dest)) &&
ip_get_option(pcb, SOF_REUSEADDR)) {
/* pass broadcast- or multicast packets to all multicast pcbs
if SOF_REUSEADDR is set on the first match */
struct udp_pcb *mpcb;
u8_t p_header_changed = 0;
for (mpcb = udp_pcbs; mpcb != NULL; mpcb = mpcb->next) {
if (mpcb != pcb) {
/* compare PCB local addr+port to UDP destination addr+port */
if ((mpcb->local_port == dest) &&
((!broadcast && ip_addr_isany(&mpcb->local_ip)) ||
ip_addr_cmp(&(mpcb->local_ip), ¤t_iphdr_dest) ||
#if LWIP_IGMP
ip_addr_ismulticast(¤t_iphdr_dest) ||
#endif /* LWIP_IGMP */
#if IP_SOF_BROADCAST_RECV
(broadcast && ip_get_option(mpcb, SOF_BROADCAST)))) {
#else /* IP_SOF_BROADCAST_RECV */
(broadcast))) {
#endif /* IP_SOF_BROADCAST_RECV */
/* pass a copy of the packet to all local matches */
if (mpcb->recv != NULL) {
struct pbuf *q;
/* for that, move payload to IP header again */
if (p_header_changed == 0) {
pbuf_header(p, (s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
p_header_changed = 1;
}
q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
if (q != NULL) {
err_t err = pbuf_copy(q, p);
if (err == ERR_OK) {
/* move payload to UDP data */
pbuf_header(q, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
mpcb->recv(mpcb->recv_arg, mpcb, q, ip_current_src_addr(), src);
}
}
}
}
}
}
if (p_header_changed) {
/* and move payload to UDP data again */
pbuf_header(p, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
}
}
#endif /* SO_REUSE && SO_REUSE_RXTOALL */
/* callback */
if (pcb->recv != NULL) {
/* now the recv function is responsible for freeing p */
pcb->recv(pcb->recv_arg, pcb, p, ip_current_src_addr(), src);
} else {
/* no recv function registered? then we have to free the pbuf! */
pbuf_free(p);
goto end;
}
} else {
/**
* Process an incoming UDP datagram.
*
* Given an incoming UDP datagram (as a chain of pbufs) this function
* finds a corresponding UDP PCB and hands over the pbuf to the pcbs
* recv function. If no pcb is found or the datagram is incorrect, the
* pbuf is freed.
*
* @param p pbuf to be demultiplexed to a UDP PCB.
* @param inp network interface on which the datagram was received.
*
*/
void
udp_input(struct pbuf *p, struct netif *inp)
{
struct udp_hdr *udphdr;
struct udp_pcb *pcb, *prev;
struct udp_pcb *uncon_pcb;
struct ip_hdr *iphdr;
u16_t src, dest;
u8_t local_match;
PERF_START;
UDP_STATS_INC(udp.recv);
iphdr = (struct ip_hdr *)(p->payload);
/* Check minimum length (IP header + UDP header)
* and move payload pointer to UDP header */
if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
/* drop short packets */
LWIP_DEBUGF(UDP_DEBUG,
("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
UDP_STATS_INC(udp.lenerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
udphdr = (struct udp_hdr *)p->payload;
LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));
/* convert src and dest ports to host byte order */
src = ntohs(udphdr->src);
dest = ntohs(udphdr->dest);
udp_debug_print(udphdr);
/* print the UDP source and destination */
LWIP_DEBUGF(UDP_DEBUG,
("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
"(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
ip4_addr1(&iphdr->dest), ip4_addr2(&iphdr->dest),
ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));
#if LWIP_DHCP
pcb = NULL;
/* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
if (dest == DHCP_CLIENT_PORT) {
/* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
if (src == DHCP_SERVER_PORT) {
if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
/* accept the packe if
(- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
- inp->dhcp->pcb->remote == ANY or iphdr->src */
if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &(iphdr->src)))) {
pcb = inp->dhcp->pcb;
}
}
}
} else
#endif /* LWIP_DHCP */
{
prev = NULL;
local_match = 0;
uncon_pcb = NULL;
/* Iterate through the UDP pcb list for a matching pcb.
* 'Perfect match' pcbs (connected to the remote port & ip address) are
* preferred. If no perfect match is found, the first unconnected pcb that
* matches the local port and ip address gets the datagram. */
for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
local_match = 0;
/* print the PCB local and remote address */
LWIP_DEBUGF(UDP_DEBUG,
("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
"(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));
/* compare PCB local addr+port to UDP destination addr+port */
if ((pcb->local_port == dest) &&
(ip_addr_isany(&pcb->local_ip) ||
ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)) ||
#if LWIP_IGMP
ip_addr_ismulticast(&(iphdr->dest)) ||
#endif /* LWIP_IGMP */
ip_addr_isbroadcast(&(iphdr->dest), inp))) {
local_match = 1;
if ((uncon_pcb == NULL) &&
((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
/* the first unconnected matching PCB */
uncon_pcb = pcb;
}
}
/* compare PCB remote addr+port to UDP source addr+port */
if ((local_match != 0) &&
(pcb->remote_port == src) &&
(ip_addr_isany(&pcb->remote_ip) ||
ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)))) {
/* the first fully matching PCB */
if (prev != NULL) {
/* move the pcb to the front of udp_pcbs so that is
found faster next time */
prev->next = pcb->next;
pcb->next = udp_pcbs;
udp_pcbs = pcb;
} else {
UDP_STATS_INC(udp.cachehit);
}
break;
}
prev = pcb;
}
/* no fully matching pcb found? then look for an unconnected pcb */
if (pcb == NULL) {
pcb = uncon_pcb;
}
}
/* Check checksum if this is a match or if it was directed at us. */
if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) {
LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
#if LWIP_UDPLITE
if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
/* Do the UDP Lite checksum */
#if CHECKSUM_CHECK_UDP
u16_t chklen = ntohs(udphdr->len);
if (chklen < sizeof(struct udp_hdr)) {
if (chklen == 0) {
/* For UDP-Lite, checksum length of 0 means checksum
over the complete packet (See RFC 3828 chap. 3.1) */
chklen = p->tot_len;
} else {
/* At least the UDP-Lite header must be covered by the
checksum! (Again, see RFC 3828 chap. 3.1) */
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
}
if (inet_chksum_pseudo_partial(p, (struct ip_addr *)&(iphdr->src),
(struct ip_addr *)&(iphdr->dest),
IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
LWIP_DEBUGF(UDP_DEBUG | 2,
("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
#endif /* CHECKSUM_CHECK_UDP */
} else
#endif /* LWIP_UDPLITE */
{
#if CHECKSUM_CHECK_UDP
if (udphdr->chksum != 0) {
if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
(struct ip_addr *)&(iphdr->dest),
IP_PROTO_UDP, p->tot_len) != 0) {
LWIP_DEBUGF(UDP_DEBUG | 2,
("udp_input: UDP datagram discarded due to failing checksum\n"));
UDP_STATS_INC(udp.chkerr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
}
#endif /* CHECKSUM_CHECK_UDP */
}
if(pbuf_header(p, -UDP_HLEN)) {
/* Can we cope with this failing? Just assert for now */
LWIP_ASSERT("pbuf_header failed\n", 0);
UDP_STATS_INC(udp.drop);
snmp_inc_udpinerrors();
pbuf_free(p);
goto end;
}
if (pcb != NULL) {
snmp_inc_udpindatagrams();
/* callback */
if (pcb->recv != NULL) {
/* now the recv function is responsible for freeing p */
struct ip_addr iphdrsrc; // __packed hack
iphdrsrc.addr = iphdr->src.addr;
pcb->recv(pcb->recv_arg, pcb, p, &iphdrsrc, src);
} else {
/* no recv function registered? then we have to free the pbuf! */
pbuf_free(p);
goto end;
}
} else {
LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));
#if LWIP_ICMP
/* No match was found, send ICMP destination port unreachable unless
destination address was broadcast/multicast. */
if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
!ip_addr_ismulticast(&iphdr->dest)) {
/* move payload pointer back to ip header */
pbuf_header(p, (IPH_HL(iphdr) * 4) + UDP_HLEN);
LWIP_ASSERT("p->payload == iphdr", (p->payload == iphdr));
icmp_dest_unreach(p, ICMP_DUR_PORT);
}
#endif /* LWIP_ICMP */
UDP_STATS_INC(udp.proterr);
UDP_STATS_INC(udp.drop);
snmp_inc_udpnoports();
pbuf_free(p);
}
} else {
pbuf_free(p);
}
end:
PERF_STOP("udp_input");
}
