Consistent precondition formatting

Our "Preconditions:" blocks are very useful to determine the input invariants,
but they are bit inconsistent throughout the codebase, which makes them harder
to read (particularly cases with 5+ conditions in a single paragraph).

I've reformatted all of the cases to fit in simple rules:

1. Cases with a single condition are placed on a single line.
2. Cases with multiple conditions are placed in a bulleted list.

This format has been added to the style guide.

I've also mentioned "Postconditions:", though those are much less frequently
used, and all uses already match this style.

PiperOrigin-RevId: 327687465

2 files changed, 9 insertions, 7 deletions

diff --git a/pkg/tcpip/stack/conntrack.go b/pkg/tcpip/stack/conntrack.go
index 7dd344b4f..836682ea0 100644
--- a/pkg/tcpip/stack/conntrack.go
+++ b/pkg/tcpip/stack/conntrack.go
@@ -572,7 +572,9 @@ func (ct *ConnTrack) reapUnused(start int, prevInterval time.Duration) (int, tim
 // reapTupleLocked tries to remove tuple and its reply from the table. It
 // returns whether the tuple's connection has timed out.
 //
-// Preconditions: ct.mu is locked for reading and bucket is locked.
+// Preconditions:
+// * ct.mu is locked for reading.
+// * bucket is locked.
 func (ct *ConnTrack) reapTupleLocked(tuple *tuple, bucket int, now time.Time) bool {
 	if !tuple.conn.timedOut(now) {
 		return false
diff --git a/pkg/tcpip/stack/iptables.go b/pkg/tcpip/stack/iptables.go
index c37da814f..41ef4236b 100644
--- a/pkg/tcpip/stack/iptables.go
+++ b/pkg/tcpip/stack/iptables.go
@@ -315,8 +315,8 @@ func (it *IPTables) startReaper(interval time.Duration) {
 // should not go forward.
 //
 // Preconditions:
-// - pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
-// - pkt.NetworkHeader is not nil.
+// * pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
+// * pkt.NetworkHeader is not nil.
 //
 // NOTE: unlike the Check API the returned map contains packets that should be
 // dropped.
@@ -341,8 +341,8 @@ func (it *IPTables) CheckPackets(hook Hook, pkts PacketBufferList, gso *GSO, r *
 }
 
 // Preconditions:
-// - pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
-// - pkt.NetworkHeader is not nil.
+// * pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
+// * pkt.NetworkHeader is not nil.
 func (it *IPTables) checkChain(hook Hook, pkt *PacketBuffer, table Table, ruleIdx int, gso *GSO, r *Route, address tcpip.Address, nicName string) chainVerdict {
 	// Start from ruleIdx and walk the list of rules until a rule gives us
 	// a verdict.
@@ -388,8 +388,8 @@ func (it *IPTables) checkChain(hook Hook, pkt *PacketBuffer, table Table, ruleId
 }
 
 // Preconditions:
-// - pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
-// - pkt.NetworkHeader is not nil.
+// * pkt is a IPv4 packet of at least length header.IPv4MinimumSize.
+// * pkt.NetworkHeader is not nil.
 func (it *IPTables) checkRule(hook Hook, pkt *PacketBuffer, table Table, ruleIdx int, gso *GSO, r *Route, address tcpip.Address, nicName string) (RuleVerdict, int) {
 	rule := table.Rules[ruleIdx]