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Decompose the codec, document the session surface and record the review decisions

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Lilleman auf Larv
2026-08-26 22:59:39 +02:00
parent 6d842a8539
commit 435fa42708
10 changed files with 186 additions and 96 deletions
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src/pdu.ts
+120 -68
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@@ -1,7 +1,7 @@
import type { CommandName, PduParams, PduParamsInput } from './defs/commands.ts';
import type { CommandDefinition, CommandName, PduParams, PduParamsInput } from './defs/commands.ts';
import type { ErrorName } from './defs/errors.ts';
import type { ParamValue } from './defs/types.ts';
import type { Result } from './result.ts';
import type { Result, VoidResult } from './result.ts';
import type { Tlv } from './defs/tlvs.ts';
import { cmds, commandNameById, isCommandName } from './defs/commands.ts';
import { consts } from './defs/constants.ts';
@@ -79,46 +79,31 @@ function tagIdOf(name: string, input: TlvInput): Result<{ tagId: number }> {
return { tagId };
}
function buildPdu(
cmdName: CommandName,
cmdStatus: ErrorName,
seqNr: number,
/** Encoding a string short_message also settles data_coding and sm_length. */
function resolveShortMessage(
params: Record<string, ParamValue | undefined>,
tlvs: Record<string, TlvInput> | undefined,
): Result<{ buffer: Buffer }> {
const definition = cmds[cmdName];
): Record<string, ParamValue | undefined> {
const message = params.short_message;
if (!definition) {
return { err: new Error(`Invalid cmdName: ${JSON.stringify(cmdName)}`) };
}
if (typeof message !== 'string') return { ...params };
if (!isErrorName(cmdStatus)) {
return { err: new Error(`Invalid cmdStatus: ${JSON.stringify(cmdStatus)}`) };
}
const dataCoding = params.data_coding;
const encoding = typeof dataCoding === 'number' ? encodingByDataCoding(dataCoding) : detect(message);
const encoded = encodeMessage(message, encoding);
if (!Number.isInteger(seqNr) || seqNr < 0 || seqNr > maxSeqNr) {
return { err: new Error(`Invalid seqNr: ${JSON.stringify(seqNr)}`) };
}
const resolved = { ...params };
const message = resolved.short_message;
// A string short_message is encoded here, which also settles data_coding and sm_length.
if (typeof message === 'string') {
const dataCoding = resolved.data_coding;
const encoding = typeof dataCoding === 'number'
? encodingByDataCoding(dataCoding)
: detect(message);
const encoded = encodeMessage(message, encoding);
resolved.short_message = encoded.buffer;
resolved.sm_length = encoded.buffer.length;
if (typeof dataCoding !== 'number') {
resolved.data_coding = consts.ENCODING[encoded.encoding];
}
}
return {
...params,
data_coding: typeof dataCoding === 'number' ? dataCoding : consts.ENCODING[encoded.encoding],
short_message: encoded.buffer,
sm_length: encoded.buffer.length,
};
}
function writeParams(
definition: CommandDefinition,
resolved: Record<string, ParamValue | undefined>,
cmdName: CommandName,
): Result<{ chunks: Buffer[] }> {
const chunks: Buffer[] = [];
for (const [name, type] of Object.entries(definition.params ?? {})) {
@@ -139,6 +124,12 @@ function buildPdu(
chunks.push(chunk);
}
return { chunks };
}
function writeTlvs(tlvs: Record<string, TlvInput> | undefined): Result<{ chunks: Buffer[] }> {
const chunks: Buffer[] = [];
for (const [name, tlv] of Object.entries(tlvs ?? {})) {
const tag = tagIdOf(name, tlv);
@@ -169,7 +160,39 @@ function buildPdu(
chunks.push(chunk);
}
const body = Buffer.concat(chunks);
return { chunks };
}
function buildPdu(
cmdName: CommandName,
cmdStatus: ErrorName,
seqNr: number,
params: Record<string, ParamValue | undefined>,
tlvs: Record<string, TlvInput> | undefined,
): Result<{ buffer: Buffer }> {
const definition = cmds[cmdName];
if (!definition) {
return { err: new Error(`Invalid cmdName: ${JSON.stringify(cmdName)}`) };
}
if (!isErrorName(cmdStatus)) {
return { err: new Error(`Invalid cmdStatus: ${JSON.stringify(cmdStatus)}`) };
}
if (!Number.isInteger(seqNr) || seqNr < 0 || seqNr > maxSeqNr) {
return { err: new Error(`Invalid seqNr: ${JSON.stringify(seqNr)}`) };
}
const written = writeParams(definition, resolveShortMessage(params), cmdName);
if (written.err) return { err: written.err };
const writtenTlvs = writeTlvs(tlvs);
if (writtenTlvs.err) return { err: writtenTlvs.err };
const body = Buffer.concat([...written.chunks, ...writtenTlvs.chunks]);
const header = Buffer.alloc(16);
header.writeUInt32BE(body.length + 16, 0);
@@ -223,22 +246,11 @@ function parseTlvs(
return { offset, tlvs };
}
function parseOnce(pdu: Buffer, trailingNull: boolean): Result<{ aligned: boolean; pduObj: PduObject }> {
const cmdLength = pdu.readUInt32BE(0);
const cmdId = pdu.readUInt32BE(4);
const cmdName = commandNameById(cmdId);
if (!cmdName) {
return { err: new Error(`Unknown PDU command id: ${String(cmdId)}`) };
}
const cmdStatusId = pdu.readUInt32BE(8);
const seqNr = pdu.readUInt32BE(12);
if (seqNr > maxSeqNr) {
return { err: new Error(`Invalid seqNr, exceeds ${String(maxSeqNr)}: ${String(seqNr)}`) };
}
function readParams(
cmdName: CommandName,
pdu: Buffer,
trailingNull: boolean,
): Result<{ offset: number; params: Record<string, ParamValue> }> {
const params: Record<string, ParamValue> = {};
let offset = 16;
@@ -255,10 +267,34 @@ function parseOnce(pdu: Buffer, trailingNull: boolean): Result<{ aligned: boolea
if (name === 'short_message' && trailingNull) offset++;
}
const parsed = parseTlvs(pdu, offset, cmdLength);
return { offset, params };
}
function parseOnce(pdu: Buffer, trailingNull: boolean): Result<{ aligned: boolean; pduObj: PduObject }> {
const cmdLength = pdu.readUInt32BE(0);
const cmdId = pdu.readUInt32BE(4);
const cmdName = commandNameById(cmdId);
if (!cmdName) {
return { err: new Error(`Unknown PDU command id: ${String(cmdId)}`) };
}
const cmdStatusId = pdu.readUInt32BE(8);
const seqNr = pdu.readUInt32BE(12);
if (seqNr > maxSeqNr) {
return { err: new Error(`Invalid seqNr, exceeds ${String(maxSeqNr)}: ${String(seqNr)}`) };
}
const read = readParams(cmdName, pdu, trailingNull);
if (read.err) return { err: read.err };
const parsed = parseTlvs(pdu, read.offset, cmdLength);
if (parsed.err) return { err: parsed.err };
const params = read.params;
const message = params.short_message;
const esmClass = numberOr(params.esm_class, 0);
@@ -282,7 +318,7 @@ function parseOnce(pdu: Buffer, trailingNull: boolean): Result<{ aligned: boolea
};
}
export function pduToObj(pdu: Buffer): Result<{ pduObj: PduObject }> {
function checkFraming(pdu: Buffer): VoidResult {
if (pdu.length < 16) {
return { err: new Error(`PDU is too short, minimum is 16 octets, got ${String(pdu.length)}`) };
}
@@ -297,6 +333,14 @@ export function pduToObj(pdu: Buffer): Result<{ pduObj: PduObject }> {
return { err: new Error(`cmd_length ${String(cmdLength)} exceeds the ${String(pdu.length)} octets given`) };
}
return {};
}
export function pduToObj(pdu: Buffer): Result<{ pduObj: PduObject }> {
const framing = checkFraming(pdu);
if (framing.err) return { err: framing.err };
const plain = parseOnce(pdu, false);
if (!plain.err && plain.aligned) return { pduObj: plain.pduObj };
@@ -311,6 +355,25 @@ export function pduToObj(pdu: Buffer): Result<{ pduObj: PduObject }> {
return { err: plain.err };
}
/** Fields the response shares with the request are echoed back unless the caller overrode them. */
function echoParams(
respName: CommandName,
pdu: PduObject,
params: Record<string, ParamValue>,
): Record<string, ParamValue> {
const respParams: Record<string, ParamValue> = { ...params };
for (const name of Object.keys(cmds[respName]?.params ?? {})) {
const value = pdu.params[name];
if (respParams[name] === undefined && value !== undefined) {
respParams[name] = value;
}
}
return respParams;
}
export function pduReturn(
pdu: Buffer | PduObject,
status: ErrorName = 'ESME_ROK',
@@ -329,16 +392,5 @@ export function pduReturn(
return { err: new Error(`"${pdu.cmdName}" has no response command`) };
}
const respParams: Record<string, ParamValue> = { ...params };
// Fields the response shares with the request are echoed back unless the caller overrode them.
for (const name of Object.keys(cmds[respName]?.params ?? {})) {
const value = pdu.params[name];
if (respParams[name] === undefined && value !== undefined) {
respParams[name] = value;
}
}
return buildPdu(respName, status, pdu.seqNr, respParams, tlvs);
return buildPdu(respName, status, pdu.seqNr, echoParams(respName, pdu, params), tlvs);
}