test-blob-parse.c

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/*
 * Based on certificate dump functionality from ucert.c:
 *
 *  Copyright (C) 2018 Daniel Golle <daniel@makrotopia.org>
 *  SPDX-License-Identifier: GPL-3.0
 *
 */
 
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <libgen.h>
 
#include "blob.h"
#include "list.h"
#include "blobmsg_json.h"
 
#define CERT_BUF_LEN 4096
 
/*
 * ucert structure
 * |               BLOB                    |
 * |    SIGNATURE    |       PAYLOAD       |
 * |                 |[ BLOBMSG CONTAINER ]|
 * |                 |[[T,i,v,e,f,pubkey ]]|
 */
enum cert_attr {
        CERT_ATTR_SIGNATURE,
        CERT_ATTR_PAYLOAD,
        CERT_ATTR_MAX
};
 
static const struct blob_attr_info cert_policy[CERT_ATTR_MAX] = {
        [CERT_ATTR_SIGNATURE] = { .type = BLOB_ATTR_BINARY },
        [CERT_ATTR_PAYLOAD] = { .type = BLOB_ATTR_NESTED },
};
 
enum cert_cont_attr {
        CERT_CT_ATTR_PAYLOAD,
        CERT_CT_ATTR_MAX
};
 
enum cert_payload_attr {
        CERT_PL_ATTR_CERTTYPE,
        CERT_PL_ATTR_CERTID,
        CERT_PL_ATTR_VALIDFROMTIME,
        CERT_PL_ATTR_EXPIRETIME,
        CERT_PL_ATTR_PUBKEY,
        CERT_PL_ATTR_KEY_FINGERPRINT,
        CERT_PL_ATTR_MAX
};
 
enum certtype_id {
        CERTTYPE_UNSPEC,
        CERTTYPE_AUTH,
        CERTTYPE_REVOKE
};
 
/* list to store certificate chain at runtime */
struct cert_object {
        struct list_head list;
        struct blob_attr *cert[CERT_ATTR_MAX];
};
 
static int cert_load(const char *certfile, struct list_head *chain)
{
        FILE *f;
        struct blob_attr *certtb[CERT_ATTR_MAX];
        struct blob_attr *bufpt;
        struct cert_object *cobj;
        char *filebuf = NULL;
        int ret = 0, pret = 0;
        size_t len, pos = 0;
 
        f = fopen(certfile, "r");
        if (!f)
                return 1;
 
        filebuf = malloc(CERT_BUF_LEN+1);
        if (!filebuf)
                return 1;
 
        len = fread(filebuf, 1, CERT_BUF_LEN, f);
        if (len < 64) {
                free(filebuf);
                return 1;
        }
 
        ret = ferror(f) || !feof(f);
        fclose(f);
        if (ret) {
                free(filebuf);
                return 1;
        }
 
        bufpt = (struct blob_attr *)filebuf;
        do {
                pret = blob_parse_untrusted(bufpt, len, certtb, cert_policy, CERT_ATTR_MAX);
                if (pret <= 0)
                        /* no attributes found */
                        break;
 
                if (pos + blob_pad_len(bufpt) > len)
                        /* blob exceeds filebuffer */
                        break;
                else
                        pos += blob_pad_len(bufpt);
 
                if (!certtb[CERT_ATTR_SIGNATURE])
                        /* no signature -> drop */
                        break;
 
                cobj = calloc(1, sizeof(*cobj));
                cobj->cert[CERT_ATTR_SIGNATURE] = blob_memdup(certtb[CERT_ATTR_SIGNATURE]);
                if (certtb[CERT_ATTR_PAYLOAD])
                        cobj->cert[CERT_ATTR_PAYLOAD] = blob_memdup(certtb[CERT_ATTR_PAYLOAD]);
 
                list_add_tail(&cobj->list, chain);
                ret += pret;
        /* repeat parsing while there is still enough remaining data in buffer */
        } while(len > pos + sizeof(struct blob_attr) && (bufpt = blob_next(bufpt)));
 
        free(filebuf);
        return (ret <= 0);
}
 
/* dump single chain element to console */
static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX])
{
        int i;
        char *json = NULL;
 
        for (i = 0; i < CERT_ATTR_MAX; i++) {
                struct blob_attr *v = cert[i];
 
                if (!v)
                        continue;
 
                switch(cert_policy[i].type) {
                case BLOB_ATTR_BINARY:
                        fprintf(stdout, "signature:\n---\n%s---\n", (char *) blob_data(v));
                        break;
                case BLOB_ATTR_NESTED:
                        json = blobmsg_format_json_indent(blob_data(v), false, 0);
                        if (!json)
                                continue;
 
                        fprintf(stdout, "payload:\n---\n%s\n---\n", json);
                        free(json);
                        break;
                }
        }
}
 
static int cert_dump(const char *certfile)
{
        struct cert_object *cobj;
        static LIST_HEAD(certchain);
        unsigned int count = 0;
 
        if (cert_load(certfile, &certchain)) {
                fprintf(stderr, "cannot parse cert %s\n", basename((char *) certfile));
                return 1;
        }
 
        list_for_each_entry(cobj, &certchain, list) {
                fprintf(stdout, "=== CHAIN ELEMENT %02u ===\n", ++count);
                cert_dump_blob(cobj->cert);
        }
 
        return 0;
}
 
int main(int argc, char *argv[])
{
        if (argc != 2) {
                fprintf(stderr, "Usage: %s <cert.ucert>\n", argv[0]);
                return 3;
        }
 
        cert_dump(argv[1]);
 
        return 0;
}