verify-commits: Move trusted-keys valid sig check into verify-commits itself

Instead of having gpg.sh check against the trusted keys for a valid
signature, do it inside of verify-commits itself.

This also allows us to use the same trusted-keys throughout the
verify-commits.py check rather than it possibly being modified during
the clean merge check.

contrib/verify-commits/gpg.sh

@@ -5,12 +5,9 @@
 
 export LC_ALL=C
 INPUT=$(cat /dev/stdin)
-VALID=false
-REVSIG=false
-IFS='
-'
 if [ "$BITCOIN_VERIFY_COMMITS_ALLOW_SHA1" = 1 ]; then
-	GPG_RES="$(printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null)"
+    printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null
+    exit $?
 else
 	# Note how we've disabled SHA1 with the --weak-digest option, disabling
 	# signatures - including selfsigs - that use SHA1. While you might think that
@@ -20,12 +17,12 @@ else
 	# an attacker could construct a pull-req that results in a commit object that
 	# they've created a collision for. Not the most likely attack, but preventing
 	# it is pretty easy so we do so as a "belt-and-suspenders" measure.
-	GPG_RES=""
 	for LINE in $(gpg --version); do
 		case "$LINE" in
 			"gpg (GnuPG) 1.4.1"*|"gpg (GnuPG) 2.0."*)
 				echo "Please upgrade to at least gpg 2.1.10 to check for weak signatures" > /dev/stderr
-				GPG_RES="$(printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null)"
+                                printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null
+                                exit $?
 				;;
 			# We assume if you're running 2.1+, you're probably running 2.1.10+
 			# gpg will fail otherwise
@@ -33,33 +30,6 @@ else
 			# gpg will fail otherwise
 		esac
 	done
-	[ "$GPG_RES" = "" ] && GPG_RES="$(printf '%s\n' "$INPUT" | gpg --trust-model always --weak-digest sha1 "$@" 2>/dev/null)"
-fi
-for LINE in $GPG_RES; do
-	case "$LINE" in
-	"[GNUPG:] VALIDSIG "*)
-		while read KEY; do
-			[ "${LINE#?GNUPG:? VALIDSIG * * * * * * * * * }" = "$KEY" ] && VALID=true
-		done < ./contrib/verify-commits/trusted-keys
-		;;
-	"[GNUPG:] REVKEYSIG "*)
-		[ "$BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG" != 1 ] && exit 1
-		REVSIG=true
-		GOODREVSIG="[GNUPG:] GOODSIG ${LINE#* * *}"
-		;;
-	"[GNUPG:] EXPKEYSIG "*)
-		[ "$BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG" != 1 ] && exit 1
-		REVSIG=true
-		GOODREVSIG="[GNUPG:] GOODSIG ${LINE#* * *}"
-		;;
-	esac
-done
-if ! $VALID; then
-	exit 1
-fi
-if $VALID && $REVSIG; then
-	printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null | grep "^\[GNUPG:\] \(NEWSIG\|SIG_ID\|VALIDSIG\)"
-	echo "$GOODREVSIG"
-else
-	printf '%s\n' "$INPUT" | gpg --trust-model always "$@" 2>/dev/null
+        printf '%s\n' "$INPUT" | gpg --trust-model always --weak-digest sha1 "$@" 2>/dev/null
+        exit $?
 fi

contrib/verify-commits/verify-commits.py

@@ -92,6 +92,8 @@ def main():
         unclean_merge_allowed = f.read().splitlines()
     with open(dirname + "/allow-incorrect-sha512-commits", "r", encoding="utf8") as f:
         incorrect_sha512_allowed = f.read().splitlines()
+    with open(dirname + "/trusted-keys", "r", encoding="utf8") as f:
+        trusted_keys = f.read().splitlines()
 
     # Set commit and branch and set variables
     current_commit = args.commit
@@ -120,10 +122,19 @@ def main():
             no_sha1 = False
 
         os.environ['BITCOIN_VERIFY_COMMITS_ALLOW_SHA1'] = "0" if no_sha1 else "1"
-        os.environ['BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG'] = "1" if current_commit in revsig_allowed else "0"
+        allow_revsig = current_commit in revsig_allowed
 
         # Check that the commit (and parents) was signed with a trusted key
-        if subprocess.call([GIT, '-c', 'gpg.program={}/gpg.sh'.format(dirname), 'verify-commit', current_commit], stdout=subprocess.DEVNULL):
+        valid_sig = False
+        verify_res = subprocess.run([GIT, '-c', 'gpg.program={}/gpg.sh'.format(dirname), 'verify-commit', "--raw", current_commit], capture_output=True)
+        for line in verify_res.stderr.decode().splitlines():
+            if line.startswith("[GNUPG:] VALIDSIG "):
+                key = line.split(" ")[-1]
+                valid_sig = key in trusted_keys
+            elif (line.startswith("[GNUPG:] REVKEYSIG ") or line.startswith("[GNUPG:] EXPKEYSIG ")) and not allow_revsig:
+                valid_sig = False
+                break
+        if not valid_sig:
             if prev_commit != "":
                 print("No parent of {} was signed with a trusted key!".format(prev_commit), file=sys.stderr)
                 print("Parents are:", file=sys.stderr)