[PATCH v2 02/10] crypto: make shared crypto code behave library-like

Subject: [PATCH v2 02/10] crypto: make shared crypto code behave library-like

Date: Fri, 15 Sep 2017 01:53:51 -0400

To: Notmuch Mail

Cc:

From: Daniel Kahn Gillmor


If we're going to reuse the crypto code across both the library and
the client, then it needs to report error states properly and not
write to stderr.
---
 lib/database.cc |  6 ++++
 lib/notmuch.h   | 17 +++++++++++
 mime-node.c     |  7 ++++-
 util/crypto.c   | 89 ++++++++++++++++++++++++++++-----------------------------
 util/crypto.h   |  6 ++--
 5 files changed, 76 insertions(+), 49 deletions(-)

diff --git a/lib/database.cc b/lib/database.cc
index 79eb3d69..82a3d463 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -413,6 +413,12 @@ notmuch_status_to_string (notmuch_status_t status)
 	return "Operation requires a database upgrade";
     case NOTMUCH_STATUS_PATH_ERROR:
 	return "Path supplied is illegal for this function";
+    case NOTMUCH_STATUS_MALFORMED_CRYPTO_PROTOCOL:
+	return "Crypto protocol missing, malformed, or unintelligible";
+    case NOTMUCH_STATUS_FAILED_CRYPTO_CONTEXT_CREATION:
+	return "Crypto engine initialization failure";
+    case NOTMUCH_STATUS_UNKNOWN_CRYPTO_PROTOCOL:
+	return "Unknown crypto protocol";
     default:
     case NOTMUCH_STATUS_LAST_STATUS:
 	return "Unknown error status value";
diff --git a/lib/notmuch.h b/lib/notmuch.h
index f26565f3..6c76fb40 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -191,6 +191,23 @@ typedef enum _notmuch_status {
      * function, in a way not covered by a more specific argument.
      */
     NOTMUCH_STATUS_ILLEGAL_ARGUMENT,
+    /**
+     * A MIME object claimed to have cryptographic protection which
+     * notmuch tried to handle, but the protocol was not specified in
+     * an intelligible way.
+     */
+    NOTMUCH_STATUS_MALFORMED_CRYPTO_PROTOCOL,
+    /**
+     * Notmuch attempted to do crypto processing, but could not
+     * initialize the engine needed to do so.
+     */
+    NOTMUCH_STATUS_FAILED_CRYPTO_CONTEXT_CREATION,
+    /**
+     * A MIME object claimed to have cryptographic protection, and
+     * notmuch attempted to process it, but the specific protocol was
+     * something that notmuch doesn't know how to handle.
+     */
+    NOTMUCH_STATUS_UNKNOWN_CRYPTO_PROTOCOL,
     /**
      * Not an actual status value. Just a way to find out how many
      * valid status values there are.
diff --git a/mime-node.c b/mime-node.c
index d9ff7de1..6cd7d2de 100644
--- a/mime-node.c
+++ b/mime-node.c
@@ -265,7 +265,12 @@ _mime_node_create (mime_node_t *parent, GMimeObject *part)
 	|| (GMIME_IS_MULTIPART_SIGNED (part) && node->ctx->crypto->verify)) {
 	GMimeContentType *content_type = g_mime_object_get_content_type (part);
 	const char *protocol = g_mime_content_type_get_parameter (content_type, "protocol");
-	cryptoctx = _notmuch_crypto_get_gmime_context (node->ctx->crypto, protocol);
+	notmuch_status_t status;
+	status = _notmuch_crypto_get_gmime_ctx_for_protocol (node->ctx->crypto,
+							     protocol, &cryptoctx);
+	if (status) /* this is a warning, not an error */
+	    fprintf (stderr, "Warning: %s (%s).\n", notmuch_status_to_string (status),
+		     protocol ? protocol : "(NULL)");
 	if (!cryptoctx)
 	    return NULL;
     }
diff --git a/util/crypto.c b/util/crypto.c
index 97e8c8f4..e7908197 100644
--- a/util/crypto.c
+++ b/util/crypto.c
@@ -27,86 +27,86 @@
 #define ARRAY_SIZE(arr) (sizeof (arr) / sizeof (arr[0]))
 
 #if (GMIME_MAJOR_VERSION < 3)
-/* Create a GPG context (GMime 2.6) */
-static GMimeCryptoContext*
-create_gpg_context (_notmuch_crypto_t *crypto)
+/* Create or pass on a GPG context (GMime 2.6) */
+static notmuch_status_t
+get_gpg_context (_notmuch_crypto_t *crypto, GMimeCryptoContext **ctx)
 {
-    GMimeCryptoContext *gpgctx;
+    if (ctx == NULL || crypto == NULL)
+	return NOTMUCH_STATUS_NULL_POINTER;
 
     if (crypto->gpgctx) {
-	return crypto->gpgctx;
+	*ctx = crypto->gpgctx;
+	return NOTMUCH_STATUS_SUCCESS;
     }
 
     /* TODO: GMimePasswordRequestFunc */
-    gpgctx = g_mime_gpg_context_new (NULL, crypto->gpgpath ? crypto->gpgpath : "gpg");
-    if (! gpgctx) {
-	fprintf (stderr, "Failed to construct gpg context.\n");
-	return NULL;
+    crypto->gpgctx = g_mime_gpg_context_new (NULL, crypto->gpgpath ? crypto->gpgpath : "gpg");
+    if (! crypto->gpgctx) {
+	return NOTMUCH_STATUS_FAILED_CRYPTO_CONTEXT_CREATION;
     }
-    crypto->gpgctx = gpgctx;
 
-    g_mime_gpg_context_set_use_agent ((GMimeGpgContext *) gpgctx, TRUE);
-    g_mime_gpg_context_set_always_trust ((GMimeGpgContext *) gpgctx, FALSE);
+    g_mime_gpg_context_set_use_agent ((GMimeGpgContext *) crypto->gpgctx, TRUE);
+    g_mime_gpg_context_set_always_trust ((GMimeGpgContext *) crypto->gpgctx, FALSE);
 
-    return crypto->gpgctx;
+    *ctx = crypto->gpgctx;
+    return NOTMUCH_STATUS_SUCCESS;
 }
 
-/* Create a PKCS7 context (GMime 2.6) */
-static GMimeCryptoContext*
-create_pkcs7_context (_notmuch_crypto_t *crypto)
+/* Create or pass on a PKCS7 context (GMime 2.6) */
+static notmuch_status_t 
+get_pkcs7_context (_notmuch_crypto_t *crypto, GMimeCryptoContext **ctx)
 {
-    GMimeCryptoContext *pkcs7ctx;
+    if (ctx == NULL || crypto == NULL)
+	return NOTMUCH_STATUS_NULL_POINTER;
 
-    if (crypto->pkcs7ctx)
-	return crypto->pkcs7ctx;
+    if (crypto->pkcs7ctx) {
+	*ctx = crypto->pkcs7ctx;
+	return NOTMUCH_STATUS_SUCCESS;
+    }
 
     /* TODO: GMimePasswordRequestFunc */
-    pkcs7ctx = g_mime_pkcs7_context_new (NULL);
-    if (! pkcs7ctx) {
-	fprintf (stderr, "Failed to construct pkcs7 context.\n");
-	return NULL;
+    crypto->pkcs7ctx = g_mime_pkcs7_context_new (NULL);
+    if (! crypto->pkcs7ctx) {
+	return NOTMUCH_STATUS_FAILED_CRYPTO_CONTEXT_CREATION;
     }
-    crypto->pkcs7ctx = pkcs7ctx;
 
-    g_mime_pkcs7_context_set_always_trust ((GMimePkcs7Context *) pkcs7ctx,
+    g_mime_pkcs7_context_set_always_trust ((GMimePkcs7Context *) crypto->pkcs7ctx,
 					   FALSE);
 
-    return crypto->pkcs7ctx;
+    *ctx = crypto->pkcs7ctx;
+    return NOTMUCH_STATUS_SUCCESS;
 }
 static const struct {
     const char *protocol;
-    GMimeCryptoContext *(*get_context) (_notmuch_crypto_t *crypto);
+    notmuch_status_t (*get_context) (_notmuch_crypto_t *crypto, GMimeCryptoContext **ctx);
 } protocols[] = {
     {
 	.protocol = "application/pgp-signature",
-	.get_context = create_gpg_context,
+	.get_context = get_gpg_context,
     },
     {
 	.protocol = "application/pgp-encrypted",
-	.get_context = create_gpg_context,
+	.get_context = get_gpg_context,
     },
     {
 	.protocol = "application/pkcs7-signature",
-	.get_context = create_pkcs7_context,
+	.get_context = get_pkcs7_context,
     },
     {
 	.protocol = "application/x-pkcs7-signature",
-	.get_context = create_pkcs7_context,
+	.get_context = get_pkcs7_context,
     },
 };
 
 /* for the specified protocol return the context pointer (initializing
  * if needed) */
-GMimeCryptoContext *
-_notmuch_crypto_get_gmime_context (_notmuch_crypto_t *crypto, const char *protocol)
+notmuch_status_t
+_notmuch_crypto_get_gmime_ctx_for_protocol (_notmuch_crypto_t *crypto,
+					    const char *protocol,
+					    GMimeCryptoContext **ctx)
 {
-    GMimeCryptoContext *cryptoctx = NULL;
-    size_t i;
-
-    if (! protocol) {
-	fprintf (stderr, "Cryptographic protocol is empty.\n");
-	return cryptoctx;
-    }
+    if (! protocol)
+	return NOTMUCH_STATUS_MALFORMED_CRYPTO_PROTOCOL;
 
     /* As per RFC 1847 section 2.1: "the [protocol] value token is
      * comprised of the type and sub-type tokens of the Content-Type".
@@ -114,15 +114,12 @@ _notmuch_crypto_get_gmime_context (_notmuch_crypto_t *crypto, const char *protoc
      * parameter names as defined in this document are
      * case-insensitive."  Thus, we use strcasecmp for the protocol.
      */
-    for (i = 0; i < ARRAY_SIZE (protocols); i++) {
+    for (size_t i = 0; i < ARRAY_SIZE (protocols); i++) {
 	if (strcasecmp (protocol, protocols[i].protocol) == 0)
-	    return protocols[i].get_context (crypto);
+	    return protocols[i].get_context (crypto, ctx);
     }
 
-    fprintf (stderr, "Unknown or unsupported cryptographic protocol %s.\n",
-	     protocol);
-
-    return NULL;
+    return NOTMUCH_STATUS_UNKNOWN_CRYPTO_PROTOCOL;
 }
 
 void
diff --git a/util/crypto.h b/util/crypto.h
index 6d15a6ae..d653ffb4 100644
--- a/util/crypto.h
+++ b/util/crypto.h
@@ -21,8 +21,10 @@ typedef struct _notmuch_crypto {
 
 
 #if (GMIME_MAJOR_VERSION < 3)
-GMimeCryptoContext *
-_notmuch_crypto_get_gmime_context (_notmuch_crypto_t *crypto, const char *protocol);
+notmuch_status_t
+_notmuch_crypto_get_gmime_ctx_for_protocol (_notmuch_crypto_t *crypto,
+					    const char *protocol,
+					    GMimeCryptoContext **ctx);
 #endif
 
 void
-- 
2.14.1

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