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NETWORK_REPORT: PCB offsets confirmed against struct inpcb

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struct inpcb (sys/netinet/in_pcb.h) lays out inp_faddr, inp_fport, inp_laddr,
inp_lport at 12/16/18/22 with 16-bit alignment -- exactly the ROM offsets
0x60/0x80/0x90/0xB0, in the same order in_pcblookup tests them. A 32-bit
aligned build would put them at 12/16/20/24, so the match also pins the
firmware ABI to 16-bit alignment, consistent with struct protosw's 6/10.
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arti committed 2026-10-30 01:39:49 +02:00
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@@ -3786,3 +3786,36 @@ IP (`ipintr`, `inetsw[ip_protox[]]`, `ip_output`), ICMP (`icmp_input`,
`icmp_reflect`, `icmp_send`), TCP (`tcp_input`, `tcp_dooptions`, `tcp_mss`),
UDP (`udp_input`, `udp_output`), raw IP (`rip_input`), ARP (`in_arpinput`,
`arpresolve`, `arplookup`, `arprequest`) and the PCB lookup (`in_pcblookup`).
## 55. The PCB field order proves the mapping at struct level
Section 31.1 gave the binding entry's fields from disassembly alone. The BSD
struct confirms them exactly, and the agreement is only possible with one
alignment:
```c
struct inpcb { /* sys/netinet/in_pcb.h */
struct inpcb *inp_next, *inp_prev; /* 0, 4 */
struct inpcb *inp_head; /* 8 */
struct in_addr inp_faddr; /* 12 */
u_short inp_fport; /* 16 */
struct in_addr inp_laddr; /* 18 (16-bit alignment) */
u_short inp_lport; /* 22 */
struct socket *inp_socket; /* 24 */
...
```
| field | source offset | our ROM offset | match |
|---|---|---|---|
| `inp_faddr` | 12 | `+0x60` bits = 12 | ✓ |
| `inp_fport` | 16 | `+0x80` bits = 16 | ✓ |
| `inp_laddr` | 18 | `+0x90` bits = 18 | ✓ |
| `inp_lport` | 22 | `+0xB0` bits = 22 | ✓ |
All four in the same order as `in_pcblookup()` tests them. On a 32-bit-aligned
build `inp_laddr` would sit at 20 and `inp_lport` at 24, so the exact match also
establishes that the firmware's ABI uses **16-bit alignment** — consistent with
the `struct protosw` offsets (6/10) in section 53.1.
This closes the loop on the socket layer: the ROM's offsets, the source's field
order, and the lookup algorithm are all the same object.