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#include "proto.h"
#include "util.h"
enum {
SrcPort = 0,
DstPort = 2,
Length = 4,
Checksum = 6,
Payload = 8,
};
struct udp_conn {
uint32_t lip, rip;
uint16_t lport, rport;
mac_t rmac;
void (*on_conn)(struct udp_conn *, void *); /* if non-NULL - listening, if NULL - estabilished */
void (*on_recv)(const void *, size_t, void *);
void *carg;
struct udp_conn *next, **prev;
};
struct udp_conn *conns;
void udp_listen(uint16_t port,
void (*on_conn)(struct udp_conn *, void *carg),
void (*on_recv)(const void *, size_t, void *carg),
void *carg)
{
if (!on_conn) return;
struct udp_conn *c = malloc(sizeof *c);
c->lport = port;
c->lip = state.ip;
c->on_conn = on_conn;
c->on_recv = on_recv;
c->carg = carg;
c->next = conns;
if (c->next) *(c->next->prev) = c;
c->prev = &conns;
*c->prev = c;
}
void udpc_close(struct udp_conn *c) {
if (c->next) c->next->prev = c->prev;
*(c->prev) = c->next;
free(c);
}
void udpc_send(struct udp_conn *c, const void *buf, size_t len) {
uint8_t *pkt = malloc(Payload + len);
nput16(pkt + SrcPort, c->lport);
nput16(pkt + DstPort, c->rport);
nput16(pkt + Length, Payload + len);
nput16(pkt + Checksum, 0);
memcpy(pkt + Payload, buf, len);
ipv4_send(pkt, Payload + len, (struct ipv4){
.proto = 0x11,
.src = c->lip,
.dst = c->rip,
.e.dst = c->rmac,
});
free(pkt);
}
void udp_parse(const uint8_t *buf, size_t len, struct ipv4 ip) {
uint16_t srcport = nget16(buf + SrcPort);
uint16_t dstport = nget16(buf + DstPort);
bool active = false;
for (struct udp_conn *iter = conns; iter; iter = iter->next) {
if (iter->on_conn && dstport == iter->lport) {
iter->on_conn(iter, iter->carg);
iter->on_conn = NULL;
iter->rport = srcport;
memcpy(&iter->rmac, ip.e.src, sizeof(mac_t));
iter->rip = ip.src;
}
if (iter->rip == ip.src
&& iter->rport == srcport
&& iter->lport == dstport
&& iter->on_recv)
{
active = true;
iter->on_recv(buf + Payload, len - Payload, iter->carg);
}
}
if (!active) {
uint8_t *pkt = malloc(4 + ip.hlen + 8);
nput32(pkt, 0);
memcpy(pkt + 4, ip.header, ip.hlen + 8);
icmp_send(pkt, 4 + ip.hlen + 8, (struct icmp){
.type = 3, /* destination unreachable */
.code = 3, /* port unreachable */
.ip.dst = ip.src,
.ip.e.dst = ip.e.src,
});
free(pkt);
}
}
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