cli/show: produce "email" element in sigstatus

When the certificate that signs a message is known to be valid, GMime
is capable of reporting on the e-mail address embedded in the
certificate.

We pass this information along to the caller of "notmuch show", as
often only the e-mail address of the certificate has actually been
checked/verified.

Furthermore, signature verification should probably at some point
compare the e-mail address of the caller against the sender address of
the message itself.  Having to parse what gmime thinks is a "userid"
to extract an e-mail address seems clunky and unnecessary if gmime
already thinks it knows what the e-mail address is.

See id:878s41ax6t.fsf@fifthhorseman.net for more motivation and discussion.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>

8 files changed, 36 insertions, 7 deletions

diff --git a/devel/schemata b/devel/schemata
index 28332c6b..ae84a528 100644
--- a/devel/schemata
+++ b/devel/schemata
@@ -158,6 +158,7 @@ signature = {
     created?:       unix_time,
     expires?:       unix_time,
     userid?:        string
+    email?:         string
     # if status is not "good":
     keyid?:         string
     errors?: 	    sig_errors
diff --git a/notmuch-show.c b/notmuch-show.c
index bdb87321..232557d5 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -475,6 +475,11 @@ format_part_sigstatus_sprinter (sprinter_t *sp, GMimeSignatureList *siglist)
 		    sp->map_key (sp, "userid");
 		    sp->string (sp, uid);
 		}
+		const char *email = g_mime_certificate_get_valid_email (certificate);
+		if (email) {
+		    sp->map_key (sp, "email");
+		    sp->string (sp, email);
+		}
 	    }
 	} else if (certificate) {
 	    const char *key_id = g_mime_certificate_get_fpr16 (certificate);
diff --git a/test/T350-crypto.sh b/test/T350-crypto.sh
index c1c1fccc..8dbf8935 100755
--- a/test/T350-crypto.sh
+++ b/test/T350-crypto.sh
@@ -35,7 +35,7 @@ expected='[[[{"id": "XXXXX",
  "timestamp": 946728000,
  "date_relative": "2000-01-01",
  "tags": ["inbox","signed"],
- "crypto": {"signed": {"status": [{ "status": "good", "created": 946728000, "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'"}]}},
+ "crypto": {"signed": {"status": [{ "status": "good", "created": 946728000, "email": "'"$SELF_EMAIL"'", "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'"}]}},
  "headers": {"Subject": "test signed message 001",
  "From": "Notmuch Test Suite <test_suite@notmuchmail.org>",
  "To": "test_suite@notmuchmail.org",
@@ -44,6 +44,7 @@ expected='[[[{"id": "XXXXX",
  "sigstatus": [{"status": "good",
  "fingerprint": "'$FINGERPRINT'",
  "created": 946728000,
+ "email": "'"$SELF_EMAIL"'",
  "userid": "'"$SELF_USERID"'"}],
  "content-type": "multipart/signed",
  "content": [{"id": 2,
@@ -367,7 +368,7 @@ expected='[[[{"id": "XXXXX",
  "timestamp": 946728000,
  "date_relative": "2000-01-01",
  "tags": ["encrypted","inbox"],
- "crypto": {"signed": {"status": [{ "status": "good", "created": 946728000, "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'"}],
+ "crypto": {"signed": {"status": [{ "status": "good", "created": 946728000, "fingerprint": "'$FINGERPRINT'", "email": "'"$SELF_EMAIL"'", "userid": "'"$SELF_USERID"'"}],
                        "encrypted": true },
             "decrypted": {"status": "full"}},
  "headers": {"Subject": "test encrypted message 002",
@@ -379,6 +380,7 @@ expected='[[[{"id": "XXXXX",
  "sigstatus": [{"status": "good",
  "fingerprint": "'$FINGERPRINT'",
  "created": 946728000,
+ "email": "'"$SELF_EMAIL"'",
  "userid": "'"$SELF_USERID"'"}],
  "content-type": "multipart/encrypted",
  "content": [{"id": 2,
diff --git a/test/T355-smime.sh b/test/T355-smime.sh
index b7269686..31fa4b4e 100755
--- a/test/T355-smime.sh
+++ b/test/T355-smime.sh
@@ -46,7 +46,7 @@ expected='[[[{"id": "XXXXX",
  "timestamp": 946728000,
  "date_relative": "2000-01-01",
  "tags": ["inbox","signed"],
- "crypto": {"signed": {"status": [{"fingerprint": "'$FINGERPRINT'", "status": "good","userid": "CN=Notmuch Test Suite","expires": 424242424, "created": 946728000}]}},
+ "crypto": {"signed": {"status": [{"fingerprint": "'$FINGERPRINT'", "status": "good","userid": "CN=Notmuch Test Suite", "email": "<test_suite@notmuchmail.org>", "expires": 424242424, "created": 946728000}]}},
  "headers": {"Subject": "test signed message 001",
  "From": "Notmuch Test Suite <test_suite@notmuchmail.org>",
  "To": "test_suite@notmuchmail.org",
@@ -55,6 +55,7 @@ expected='[[[{"id": "XXXXX",
  "sigstatus": [{"fingerprint": "'$FINGERPRINT'",
  "status": "good",
  "userid": "CN=Notmuch Test Suite",
+ "email": "<test_suite@notmuchmail.org>",
  "expires": 424242424,
  "created": 946728000}],
  "content-type": "multipart/signed",
diff --git a/test/T356-protected-headers.sh b/test/T356-protected-headers.sh
index 074a2345..f0aba14e 100755
--- a/test/T356-protected-headers.sh
+++ b/test/T356-protected-headers.sh
@@ -69,12 +69,12 @@ test_json_nodes <<<"$output" \
 test_begin_subtest "show cryptographic envelope on signed mail"
 output=$(notmuch show --verify --format=json id:simple-signed-mail@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
-                'crypto:[0][0][0]["crypto"]={"signed": {"status": [{"created": 1525609971, "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "status": "good"}]}}'
+                'crypto:[0][0][0]["crypto"]={"signed": {"status": [{"created": 1525609971, "fingerprint": "'$FINGERPRINT'", "email": "'"$SELF_EMAIL"'", "userid": "'"$SELF_USERID"'", "status": "good"}]}}'
 
 test_begin_subtest "verify signed protected header"
 output=$(notmuch show --verify --format=json id:signed-protected-header@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
-                'crypto:[0][0][0]["crypto"]={"signed": {"status": [{"created": 1525350527, "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "status": "good"}], "headers": ["Subject"]}}'
+                'crypto:[0][0][0]["crypto"]={"signed": {"status": [{"created": 1525350527, "fingerprint": "'$FINGERPRINT'", "email": "'"$SELF_EMAIL"'", "userid": "'"$SELF_USERID"'", "status": "good"}], "headers": ["Subject"]}}'
 
 test_begin_subtest "protected subject does not leak by default in replies"
 output=$(notmuch reply --decrypt=true --format=json id:protected-header@crypto.notmuchmail.org)
@@ -115,7 +115,7 @@ test_begin_subtest "verify protected header is both signed and encrypted"
 output=$(notmuch show --decrypt=true --format=json id:encrypted-signed@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
                 'crypto:[0][0][0]["crypto"]={
-                   "signed":{"status": [{"status": "good", "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "created": 1525812676}],
+                   "signed":{"status": [{"status": "good", "fingerprint": "'$FINGERPRINT'", "email": "'"$SELF_EMAIL"'", "userid": "'"$SELF_USERID"'", "created": 1525812676}],
                    "encrypted": true, "headers": ["Subject"]},"decrypted": {"status": "full", "header-mask": {"Subject": "Subject Unavailable"}}}' \
                 'subject:[0][0][0]["headers"]["Subject"]="Rhinoceros dinner"'
 
@@ -123,7 +123,7 @@ test_begin_subtest "verify protected header is signed even when not masked"
 output=$(notmuch show --decrypt=true --format=json id:encrypted-signed-not-masked@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
                 'crypto:[0][0][0]["crypto"]={
-                   "signed":{"status": [{"status": "good", "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "created": 1525812676}],
+                   "signed":{"status": [{"status": "good", "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "email": "'"$SELF_EMAIL"'", "created": 1525812676}],
                    "encrypted": true, "headers": ["Subject"]},"decrypted": {"status": "full"}}' \
                 'subject:[0][0][0]["headers"]["Subject"]="Rhinoceros dinner"'
 
diff --git a/test/test-lib.sh b/test/test-lib.sh
index f83f7c6a..67ad8853 100644
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -131,6 +131,7 @@ add_gnupg_home () {
     # Change this if we ship a new test key
     FINGERPRINT="5AEAB11F5E33DCE875DDB75B6D92612D94E46381"
     SELF_USERID="Notmuch Test Suite <test_suite@notmuchmail.org> (INSECURE!)"
+    SELF_EMAIL="test_suite@notmuchmail.org"
     printf '%s:6:\n' "$FINGERPRINT" | gpg --quiet --batch --no-tty --import-ownertrust
 }
 
diff --git a/util/gmime-extra.c b/util/gmime-extra.c
index 81a5b174..192cb078 100644
--- a/util/gmime-extra.c
+++ b/util/gmime-extra.c
@@ -108,6 +108,21 @@ g_mime_certificate_get_valid_userid (GMimeCertificate *cert)
 }
 
 const char *
+g_mime_certificate_get_valid_email (GMimeCertificate *cert)
+{
+    /* output e-mail address only if validity is FULL or ULTIMATE. */
+    const char *email = g_mime_certificate_get_email(cert);
+
+    if (email == NULL)
+	return email;
+    GMimeValidity validity = g_mime_certificate_get_id_validity (cert);
+
+    if (validity == GMIME_VALIDITY_FULL || validity == GMIME_VALIDITY_ULTIMATE)
+	return email;
+    return NULL;
+}
+
+const char *
 g_mime_certificate_get_fpr16 (GMimeCertificate *cert)
 {
     const char *fpr = g_mime_certificate_get_fingerprint (cert);
diff --git a/util/gmime-extra.h b/util/gmime-extra.h
index 094309ec..889e91f3 100644
--- a/util/gmime-extra.h
+++ b/util/gmime-extra.h
@@ -69,6 +69,10 @@ gint64 g_mime_utils_header_decode_date_unix (const char *date);
  * Return string for valid User ID (or NULL if no valid User ID exists)
  */
 const char *g_mime_certificate_get_valid_userid (GMimeCertificate *cert);
+/**
+ * Return string for valid e-mail address (or NULL if no valid e-mail address exists)
+ */
+const char *g_mime_certificate_get_valid_email (GMimeCertificate *cert);
 
 #ifdef __cplusplus
 }