res_phreaknet: Create temp keypair files using full path. (#57)

Rather than creating the new keypair files in the current
working directory temporarily and then moving them to the
permanent directory, use a full path (specifically within
/tmp) to create the files, to avoid permissions errors
if we can't write to the current working directory.

Resolves: #55

res/res_phreaknet.c

@@ -1033,6 +1033,8 @@ static int iax_purge_keys(void)
 	return 0;
 }
 
+#define MY_KEYPAIR_TEMPFILE_PREFIX "/tmp/" MY_KEYPAIR_NAME
+
 /*! \brief Generate a new or rotated PhreakNet public key pair and upload it to the server */
 static int gen_keypair(int rotate)
 {
@@ -1044,7 +1046,8 @@ static int gen_keypair(int rotate)
 	char *pubkey;
 	struct ast_str *str;
 	const char *clli;
-	char *const argv[] = { "astgenkey", "-q", "-n", MY_KEYPAIR_NAME, NULL };
+	struct stat st;
+	char *const argv[] = { "astgenkey", "-q", "-n", MY_KEYPAIR_TEMPFILE_PREFIX, NULL };
 
 	if (ast_strlen_zero(interlinked_api_key)) {
 		/* Can't successfully upload to server with no API key */
@@ -1091,18 +1094,22 @@ static int gen_keypair(int rotate)
 	}
 
 	/* Generate the new keypair, and wait for it to finish. */
+	ast_debug(3, "Executing: astgenkey -q -n %s\n", MY_KEYPAIR_TEMPFILE_PREFIX);
 	if (ast_safe_execvp(0, "astgenkey", argv) == -1) {
 		ast_log(LOG_WARNING, "Failed to execute astgenkey: %s\n", strerror(errno));
 		return -1;
+	} else if (stat(MY_KEYPAIR_TEMPFILE_PREFIX ".key", &st)) {
+		ast_log(LOG_WARNING, "Failed to stat %s: %s\n", MY_KEYPAIR_TEMPFILE_PREFIX ".key", strerror(errno));
+		return -1;
 	}
 
 	/* astgenkey will create files in the current working directory, not ast_config_AST_KEY_DIR.
 	 * We could chdir after we fork but before we execvp, but let's just rename the file from what it is to what it should be. */
-	if (rename(MY_KEYPAIR_NAME ".key", privkeyfile)) {
-		ast_log(LOG_WARNING, "Failed to rename file to %s: %s\n", privkeyfile, strerror(errno));
+	if (rename(MY_KEYPAIR_TEMPFILE_PREFIX ".key", privkeyfile)) {
+		ast_log(LOG_ERROR, "Failed to rename %s to %s: %s\n", MY_KEYPAIR_TEMPFILE_PREFIX ".key", privkeyfile, strerror(errno));
 		return -1;
-	} else if (rename(MY_KEYPAIR_NAME ".pub", pubkeyfile)) {
-		ast_log(LOG_WARNING, "Failed to rename file to %s: %s\n", pubkeyfile, strerror(errno));
+	} else if (rename(MY_KEYPAIR_TEMPFILE_PREFIX ".pub", pubkeyfile)) {
+		ast_log(LOG_ERROR, "Failed to rename %s to %s: %s\n", MY_KEYPAIR_TEMPFILE_PREFIX ".pub", pubkeyfile, strerror(errno));
 		return -1;
 	}