Readd the dummy lapd header... this gives valid TEI/SAPI information
Besides that the header is spoofed, we lose the information about
the channel (we will have to add our own encap type)
diff --git a/src/misdn.c b/src/misdn.c
index 6e45f2a..920349e 100644
--- a/src/misdn.c
+++ b/src/misdn.c
@@ -82,6 +82,15 @@
int16_t protocol;
} __attribute__((packed));
+struct lapd_header {
+ u_int8_t ea1 : 1;
+ u_int8_t cr : 1;
+ u_int8_t sapi : 6;
+ u_int8_t ea2 : 1;
+ u_int8_t tei : 7;
+ u_int8_t control_foo; /* fake UM's ... */
+} __attribute__((packed));
+
static_assert((int)&((struct fake_linux_lapd_header*)NULL)->hatype == 2, hatype_offset);
static_assert((int)&((struct fake_linux_lapd_header*)NULL)->halen == 4, halen_offset);
static_assert((int)&((struct fake_linux_lapd_header*)NULL)->addr == 6, addr_offset);
@@ -122,17 +131,27 @@
.pkttype = 4,
.hatype = 0,
.halen = 0,
- .addr = 0x1,
+ .addr = direction == PCAP_OUTPUT ? 0x0 : 0x1,
.protocol = ntohs(48),
};
-
+
+ struct lapd_header lapd_header = {
+ .ea1 = 0,
+ .cr = direction == PCAP_OUTPUT ? 1 : 0,
+ .sapi = addr->sapi & 0x3F,
+ .ea2 = 1,
+ .tei = addr->tei & 0x7F,
+ .control_foo = 0x13 /* UI with P set */,
+ };
struct pcaprec_hdr payload_header = {
.ts_sec = 0,
.ts_usec = 0,
.incl_len = msg->len + sizeof(struct fake_linux_lapd_header)
+ + sizeof(struct lapd_header)
- MISDN_HEADER_LEN,
.orig_len = msg->len + sizeof(struct fake_linux_lapd_header)
+ + sizeof(struct lapd_header)
- MISDN_HEADER_LEN,
};
@@ -143,6 +162,7 @@
ret = write(pcap_fd, &payload_header, sizeof(payload_header));
ret = write(pcap_fd, &header, sizeof(header));
+ ret = write(pcap_fd, &lapd_header, sizeof(lapd_header));
ret = write(pcap_fd, msg->data + MISDN_HEADER_LEN,
msg->len - MISDN_HEADER_LEN);
}