Rein in the complexity of the signature type

Given that we offer no transparency into the pmpgpsig_t type, we don't
really need to expose it outside of the library, and at this point, we
don't need it at all. Don't decode anything except when checking
signatures. For packages/files not from a sync database, we now just
read the signature file directly anyway.

Also push the decoding logic down further into the check method so we
don't need this hanging out in a less than ideal place. This will make
it easier to conditionally compile things down the road.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 53 insertions, 10 deletions

diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
index 28b7ad98..d69fd52e 100644
--- a/lib/libalpm/signing.c
+++ b/lib/libalpm/signing.c
@@ -28,6 +28,7 @@
 /* libalpm */
 #include "signing.h"
 #include "package.h"
+#include "base64.h"
 #include "util.h"
 #include "log.h"
 #include "alpm.h"
@@ -92,13 +93,48 @@ error:
 }
 
 /**
+ * Decode a loaded signature in base64 form.
+ * @param base64_data the signature to attempt to decode
+ * @param data the decoded data; must be freed by the caller
+ * @param data_len the length of the returned data
+ * @return 0 on success, 1 on failure to properly decode
+ */
+static int decode_signature(const char *base64_data,
+		unsigned char **data, int *data_len) {
+	unsigned char *usline;
+	int len;
+
+	len = strlen(base64_data);
+	usline = (unsigned char *)base64_data;
+	int ret, destlen = 0;
+	/* get the necessary size for the buffer by passing 0 */
+	ret = base64_decode(NULL, &destlen, usline, len);
+	if(ret != 0 || ret != POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL) {
+		goto error;
+	}
+	/* alloc our memory and repeat the call to decode */
+	MALLOC(data, (size_t)destlen, goto error);
+	ret = base64_decode(*data, &destlen, usline, len);
+	if(ret != 0) {
+		goto error;
+	}
+	*data_len = destlen;
+	return 0;
+
+error:
+	*data = NULL;
+	*data_len = 0;
+	return 1;
+}
+
+/**
  * Check the PGP signature for the given file.
  * @param path the full path to a file
- * @param sig PGP signature data in raw form (already decoded); if NULL, expect
- * a signature file next to 'path'
+ * @param base64_sig PGP signature data in base64 encoding; if NULL, expect a
+ * signature file next to 'path'
  * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
  */
-int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
+int _alpm_gpgme_checksig(const char *path, const char *base64_sig)
 {
 	int ret = 0;
 	gpgme_error_t err;
@@ -107,6 +143,7 @@ int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
 	gpgme_verify_result_t result;
 	gpgme_signature_t gpgsig;
 	char *sigpath = NULL;
+	unsigned char *decoded_sigdata = NULL;
 	FILE *file = NULL, *sigfile = NULL;
 
 	ALPM_LOG_FUNC;
@@ -115,7 +152,7 @@ int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
 		RET_ERR(PM_ERR_NOT_A_FILE, -1);
 	}
 
-	if(!sig) {
+	if(!base64_sig) {
 		size_t len = strlen(path) + 5;
 		CALLOC(sigpath, len, sizeof(char), RET_ERR(PM_ERR_MEMORY, -1));
 		snprintf(sigpath, len, "%s.sig", path);
@@ -124,8 +161,6 @@ int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
 			FREE(sigpath);
 			RET_ERR(PM_ERR_SIG_UNKNOWN, -1);
 		}
-	} else if(!sig->data) {
-		 RET_ERR(PM_ERR_SIG_UNKNOWN, -1);
 	}
 
 	if(gpgme_init()) {
@@ -153,9 +188,17 @@ int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
 	CHECK_ERR();
 
 	/* next create data object for the signature */
-	if(sig) {
+	if(base64_sig) {
 		/* memory-based, we loaded it from a sync DB */
-		err = gpgme_data_new_from_mem(&sigdata, (char *)sig->data, sig->len, 0);
+		int data_len;
+		int decode_ret = decode_signature(base64_sig,
+				&decoded_sigdata, &data_len);
+		if(decode_ret) {
+			ret = -1;
+			goto error;
+		}
+		err = gpgme_data_new_from_mem(&sigdata,
+				(char *)decoded_sigdata, data_len, 0);
 	} else {
 		/* file-based, it is on disk */
 		sigfile = fopen(sigpath, "rb");
@@ -222,6 +265,7 @@ error:
 		fclose(file);
 	}
 	FREE(sigpath);
+	FREE(decoded_sigdata);
 	if(err != GPG_ERR_NO_ERROR) {
 		_alpm_log(PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
 		RET_ERR(PM_ERR_GPGME, -1);
@@ -257,8 +301,7 @@ int SYMEXPORT alpm_pkg_check_pgp_signature(pmpkg_t *pkg)
 	ALPM_LOG_FUNC;
 	ASSERT(pkg != NULL, return 0);
 
-	return _alpm_gpgme_checksig(alpm_pkg_get_filename(pkg),
-			alpm_pkg_get_pgpsig(pkg));
+	return _alpm_gpgme_checksig(alpm_pkg_get_filename(pkg), pkg->base64_sig);
 }
 
 /**