jwt: Add some simple functions to parse JWTs

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/Makefile.am b/Makefile.am
index 36c22e029d6cc3a45282d54867e05535b806950b..4ab7bfd17a9961c1a40197acdc26a5a5c7f0c3f9 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -240,6 +240,8 @@ libpakfire_la_SOURCES = \
        src/pakfire/job.h \
        src/pakfire/json.c \
        src/pakfire/json.h \
+       src/pakfire/jwt.c \
+       src/pakfire/jwt.h \
        src/pakfire/key.c \
        src/pakfire/key.h \
        src/pakfire/linter.c \

diff --git a/src/pakfire/jwt.c b/src/pakfire/jwt.c
new file mode 100644 (file)
index 0000000..21444dd
--- /dev/null
+++ b/src/pakfire/jwt.c
@@ -0,0 +1,122 @@
+/*#############################################################################
+#                                                                             #
+# Pakfire - The IPFire package management system                              #
+# Copyright (C) 2025 Pakfire development team                                 #
+#                                                                             #
+# This program is free software: you can redistribute it and/or modify        #
+# it under the terms of the GNU General Public License as published by        #
+# the Free Software Foundation, either version 3 of the License, or           #
+# (at your option) any later version.                                         #
+#                                                                             #
+# This program is distributed in the hope that it will be useful,             #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of              #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
+# GNU General Public License for more details.                                #
+#                                                                             #
+# You should have received a copy of the GNU General Public License           #
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
+#                                                                             #
+#############################################################################*/
+
+#include <errno.h>
+
+#include <json.h>
+
+#include <pakfire/base64.h>
+#include <pakfire/ctx.h>
+#include <pakfire/json.h>
+#include <pakfire/jwt.h>
+
+static int pakfire_jwt_find_payload(const char* token, const char** payload, size_t* length) {
+       const char* p = NULL;
+       size_t l = 0;
+
+       // Walk through the token character by character...
+       while (token && *token) {
+               switch (*token++) {
+                       case '.':
+                               // If we have found the first dot, the payload starts right after it
+                               if (!p) {
+                                       p = token;
+
+                               // If we have hit the second dot, we have found the end of the payload
+                               } else {
+                                       // Determine the length
+                                       l = token - p - 1;
+
+                                       // Terminate the loop
+                                       token = NULL;
+                               }
+                               break;
+               }
+       }
+
+       // If the payload is empty, we return an error
+       if (!p || !l)
+               return -EINVAL;
+
+       // Return the values
+       *payload = p;
+       *length = l;
+
+       return 0;
+}
+
+static int pakfire_jwt_decode_payload(char** payload, size_t* length, const char* token) {
+       const char* p = NULL;
+       size_t l = 0;
+       int r;
+
+       // Find the payload
+       r = pakfire_jwt_find_payload(token, &p, &l);
+       if (r < 0)
+               return r;
+
+       // Decode the payload
+       return pakfire_b64decode((unsigned char**)payload, length, p, l);
+}
+
+int pakfire_jwt_payload(struct pakfire_ctx* ctx, const char* token, struct json_object** payload) {
+       char* p = NULL;
+       size_t l = 0;
+       int r;
+
+       // Decode the payload
+       r = pakfire_jwt_decode_payload(&p, &l, token);
+       if (r < 0) {
+               ERROR(ctx, "Failed to decode the JWT payload: %s\n", strerror(-r));
+               return r;
+       }
+
+       // Parse the JSON
+       *payload = pakfire_json_parse(ctx, p, l);
+       if (!*payload)
+               return -EINVAL;
+
+       return 0;
+}
+
+time_t pakfire_jwt_expires_at(struct pakfire_ctx* ctx, const char* token) {
+       struct json_object* payload = NULL;
+       time_t expires_at = -1;
+       int r;
+
+       // Parse the payload
+       r = pakfire_jwt_payload(ctx, token, &payload);
+       if (r < 0)
+               goto ERROR;
+
+       // Fetch the expiry time
+       r = pakfire_json_get_int64(payload, "exp", &expires_at);
+       if (r < 0)
+               goto ERROR;
+
+       // Return the expiry time
+       r = expires_at;
+
+ERROR:
+       if (payload)
+               json_object_put(payload);
+
+       return r;
+}

diff --git a/src/pakfire/jwt.h b/src/pakfire/jwt.h
new file mode 100644 (file)
index 0000000..1d4f6f2
--- /dev/null
+++ b/src/pakfire/jwt.h
@@ -0,0 +1,33 @@
+/*#############################################################################
+#                                                                             #
+# Pakfire - The IPFire package management system                              #
+# Copyright (C) 2025 Pakfire development team                                 #
+#                                                                             #
+# This program is free software: you can redistribute it and/or modify        #
+# it under the terms of the GNU General Public License as published by        #
+# the Free Software Foundation, either version 3 of the License, or           #
+# (at your option) any later version.                                         #
+#                                                                             #
+# This program is distributed in the hope that it will be useful,             #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of              #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
+# GNU General Public License for more details.                                #
+#                                                                             #
+# You should have received a copy of the GNU General Public License           #
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
+#                                                                             #
+#############################################################################*/
+
+#ifndef PAKFIRE_JWT_H
+#define PAKFIRE_JWT_H
+
+#include <json.h>
+
+#include <pakfire/ctx.h>
+
+int pakfire_jwt_payload(struct pakfire_ctx* ctx,
+       const char* token, struct json_object** payload);
+
+time_t pakfire_jwt_expires_at(struct pakfire_ctx* ctx, const char* token);
+
+#endif /* PAKFIRE_JWT_H */