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Merged
markmnl merged 3 commits into from
Apr 1, 2026
Merged

flags realigned to latest spec #11

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4ef0268
flags realigned to latest spec
Apr 1, 2026
6270f93
rm todo
Apr 1, 2026
d2d3413
Merge branch 'main' into flags
markmnl Apr 1, 2026
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14 changes: 5 additions & 9 deletions TODO.md
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Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,6 @@ correctness issues, then enhancements.

## P0 — Foundational (blocks most other work)

### 1. Realign flag bit assignments to spec
**File:** `host.go` constants
Current flags are wrong: `FlagImportant` is on bit 1 (spec: bit 3),
`FlagNoReply` on bit 3 (spec: bit 4), and `FlagSkipChallenge` (bit 4) does not
exist in the spec. Missing: `FlagHasAddTo` (bit 1), `FlagCommonType` (bit 2).
All flag definitions and every usage site must be realigned.

### 2. Fix `Encode()` to produce the full message header per spec
**File:** `defs.go` `Encode()`
Expand Down Expand Up @@ -41,11 +35,13 @@ Add a `ChallengeCompleted bool` to distinguish "challenge was completed and
hash verification check in `downloadMessage` erroneously fails when the
challenge was skipped.

### 6. Fix response code constants
### ~~6. Fix response code constants~~
**File:** `host.go` constants
`RejectCodeMustChallenge` (11) and `RejectCodeCannotChallenge` (12) do not
~~`RejectCodeMustChallenge` (11) and `RejectCodeCannotChallenge` (12) do not
exist in the spec. Code 11 = "accept header" (add-to notification success).
Add missing per-user codes: 102 (user not accepting), 103 (user undisclosed).
Add missing per-user codes: 102 (user not accepting), 103 (user undisclosed).~~
**DONE:** Replaced with `AcceptCodeHeader` (11), added `RejectCodeUserNotAccepting` (102)
and `RejectCodeUserUndisclosed` (103).

---

Expand Down
66 changes: 22 additions & 44 deletions src/host.go
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Expand Up @@ -29,18 +29,15 @@ const (
InboxDirName = "in"
OutboxDirName = "out"

// TODO: Flag bit assignments do not match the revised spec. Spec defines:
// Flag bit assignments per SPEC.md:
// bit 0 = has pid, bit 1 = has add to, bit 2 = common type, bit 3 = important,
// bit 4 = no reply, bit 5 = deflate, bits 6-7 = reserved.
// Current implementation is missing FlagHasAddTo (bit 1) and FlagCommonType (bit 2),
// has FlagImportant on bit 1 (spec: bit 3), FlagNoReply on bit 3 (spec: bit 4),
// and defines FlagSkipChallenge (bit 4) which does not exist in the spec.
// All flag definitions and their usages must be realigned to the spec.
FlagHasPid uint8 = 1
FlagImportant uint8 = 1 << 1
FlagNoReply uint8 = 1 << 3
FlagSkipChallenge uint8 = 1 << 4
FlagDeflate uint8 = 1 << 5
FlagHasPid uint8 = 1
FlagHasAddTo uint8 = 1 << 1
FlagCommonType uint8 = 1 << 2
FlagImportant uint8 = 1 << 3
FlagNoReply uint8 = 1 << 4
FlagDeflate uint8 = 1 << 5

RejectCodeInvalid uint8 = 1
RejectCodeUnsupportedVersion uint8 = 2
Expand All @@ -52,19 +49,12 @@ const (
RejectCodeFutureTime uint8 = 8
RejectCodeTimeTravel uint8 = 9
RejectCodeDuplicate uint8 = 10
// TODO: Spec defines code 11 as "accept header" (message header received for
// add-to-only messages). RejectCodeMustChallenge (11) and
// RejectCodeCannotChallenge (12) do not exist in the spec and should be
// replaced with the spec-defined code 11 = accept header.
RejectCodeMustChallenge uint8 = 11
RejectCodeCannotChallenge uint8 = 12

RejectCodeUserUnknown uint8 = 100
RejectCodeUserFull uint8 = 101
// TODO: Add missing per-user response codes from the spec:
// 102 = user not accepting (known user but not accepting new messages)
// 103 = user undisclosed (no reason given; MAY be used instead of 100-102
// so Host B does not have to disclose the reason).
AcceptCodeHeader uint8 = 11

RejectCodeUserUnknown uint8 = 100
RejectCodeUserFull uint8 = 101
RejectCodeUserNotAccepting uint8 = 102
RejectCodeUserUndisclosed uint8 = 103

RejectCodeAccept uint8 = 200
)
Expand Down Expand Up @@ -92,14 +82,16 @@ func responseCodeName(code uint8) string {
return "time travel"
case RejectCodeDuplicate:
return "duplicate"
case RejectCodeMustChallenge:
return "must challenge"
case RejectCodeCannotChallenge:
return "cannot challenge"
case AcceptCodeHeader:
return "accept header"
case RejectCodeUserUnknown:
return "user unknown"
case RejectCodeUserFull:
return "user full"
case RejectCodeUserNotAccepting:
return "user not accepting"
case RejectCodeUserUndisclosed:
return "user undisclosed"
case RejectCodeAccept:
return "accept"
default:
Expand All @@ -119,7 +111,6 @@ var MinDownloadRate float64 = 5000
var MinUploadRate float64 = 5000
var ReadBufferSize = 1600
var MaxMessageSize = uint32(1024 * 10)
var AllowSkipChallenge = 0
var DataDir = "got on startup"
var Domain = "got on startup"
var IDURI = "got on startup"
Expand All @@ -136,7 +127,6 @@ func loadEnvConfig() {
MinUploadRate = env.GetFloatDefault("FMSG_MIN_UPLOAD_RATE", 5000)
ReadBufferSize = env.GetIntDefault("FMSG_READ_BUFFER_SIZE", 1600)
MaxMessageSize = uint32(env.GetIntDefault("FMSG_MAX_MSG_SIZE", 1024*10))
AllowSkipChallenge = env.GetIntDefault("FMSG_ALLOW_SKIP_CHALLENGE", 0)
}

// Updates DataDir from environment, panics if not a valid directory.
Expand Down Expand Up @@ -505,22 +495,10 @@ func readHeader(c net.Conn) (*FMsgHeader, *bufio.Reader, error) {
// at address in connection supplied by verifying the remote IP is in the
// sender's _fmsg.<sender-domain> authorised IP set.
// TODO [Spec step 2]: The spec defines challenge modes (NEVER, ALWAYS,
// HAS_NOT_PARTICIPATED, DIFFERENT_DOMAIN) as implementation choices — the
// FlagSkipChallenge mechanism is not part of the spec. Refactor to use an
// implementation-defined challenge mode instead of a sender-controlled flag.
// HAS_NOT_PARTICIPATED, DIFFERENT_DOMAIN) as implementation choices.
// Currently defaults to ALWAYS. Implement configurable challenge mode.
func challenge(conn net.Conn, h *FMsgHeader) error {

// skip challenge if sender requested it and we allow it
if h.Flags&FlagSkipChallenge != 0 {
if AllowSkipChallenge == 1 {
log.Printf("INFO: skip challenge requested and allowed from %s", conn.RemoteAddr().String())
return nil
}
log.Printf("WARN: skip challenge requested but not allowed from %s", conn.RemoteAddr().String())
rejectAccept(conn, []byte{RejectCodeMustChallenge})
return fmt.Errorf("skip challenge requested but not allowed")
}

// verify remote IP is authorised by sender's _fmsg DNS record
remoteHost, _, err := net.SplitHostPort(conn.RemoteAddr().String())
if err != nil {
Expand Down Expand Up @@ -598,7 +576,7 @@ func validateMsgRecvForAddr(h *FMsgHeader, addr *FMsgAddress) (code uint8, err e
// undisclosed). Currently RejectCodeUserUnknown (100) is returned which is
// incorrect — code 100 means the address is unknown to the host.
if !detail.AcceptingNew {
return RejectCodeUserUnknown, nil
return RejectCodeUserNotAccepting, nil
}

// check user limits
Expand Down
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