envelope: a signed value names its swarm

Review 3.1, part of finding 12: a signed value's payload bound path,
user, time and prev, but not the swarm. A user with the same name and
key in two swarms could have an envelope replayed from one into the
other, wherever the path holds no envelope yet (prev "").

The payload now names the swarm (`swarm`), and a node takes an envelope
only for its own. /auth/whoami says the swarm, and continuum-signed and
the example in api.md sign it. Wire version 44: nodes before this
refuse such envelopes, and those after refuse the old ones.

1 files changed, 4 insertions, 2 deletions

diff --git a/scripts/continuum-signed b/scripts/continuum-signed
index dc5bd75..6dd1f4c 100755
--- a/scripts/continuum-signed
+++ b/scripts/continuum-signed
@@ -96,10 +96,12 @@ write() {
         cv1.*) prev=$(printf %s "$current" | sha256sum | cut -d' ' -f1) ;;
         *) prev= ;;
     esac
+    swarm=$(curl -sf -H "Authorization: Bearer $CONTINUUM_TOKEN" "$url/auth/whoami" |
+        jq -r .swarm) || die "no swarm from $url"
     # The exact bytes signed and sent: one line of JSON, no newline.
-    jq -cnj --arg path "$1" --argjson value "$2" --arg user "$user" \
+    jq -cnj --arg swarm "$swarm" --arg path "$1" --argjson value "$2" --arg user "$user" \
         --argjson at "$(date +%s)000" --arg prev "$prev" \
-        '{path: ($path | split("/")), value: $value, user: $user, at: $at, prev: $prev}' \
+        '{swarm: $swarm, path: ($path | split("/")), value: $value, user: $user, at: $at, prev: $prev}' \
         >"$work/payload" || die "not JSON: $2"
     sign "$work/payload" continuum-value
     { cat "$work/payload"; echo; cat "$work/payload.sig"; } |