loc_database_verify(3)

Name

loc_database_verify - Check the signature of a database

Synopsis

#include <libloc/database.h>

int loc_database_verify(struct loc_database* db, FILE* f);

Description

Databases are being signed by whoever has created them, so that nobody can change their content on the way to the user.

loc_database_verify() checks whether the database db has been signed with the private key that belongs to the public key that can be read from f, in PEM format. A database can have up to two signatures, so that the signing key can be replaced while installations that only know the old key still accept new databases. One valid signature is enough.

The public key of the IPFire Location Database is being installed with libloc, usually as /var/lib/location/signing-key.pem.

Checking the signature means reading the entire database, which takes a moment. It should be done once, after a new database has been downloaded, and before the new file replaces the old one. Databases that are being reloaded are not being checked again (see loc_database_reload(3)).

Return Value

Zero is returned if the database has a valid signature. 1 is returned if it does not, which includes that the database has not been signed at all. On error, a negative error number (see errno(3)) is returned, for example -EINVAL if no public key could be read from f. errno itself is not being set.

Example

FILE* f = fopen("/var/lib/location/signing-key.pem", "r");

int r = loc_database_verify(db, f);
fclose(f);

if (r)
        fprintf(stderr, "The database cannot be trusted\n");

Authors

Michael Tremer