Git-credential-libsecret

/*
 * Copyright (C) 2011 John Szakmeister <[email protected]>
 *               2012 Philipp A. Hartmann <[email protected]>
 *               2016 Mantas Mikulėnas <[email protected]>
 *
 *  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 2 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/>.
 */

/*
 * Credits:
 * - GNOME Keyring API handling originally written by John Szakmeister
 * - ported to credential helper API by Philipp A. Hartmann
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <glib.h>
#include <libsecret/secret.h>

/*
 * This credential struct and API is simplified from git's credential.{h,c}
 */
struct credential {
    char *protocol;
    char *host;
    unsigned short port;
    char *path;
    char *username;
    char *password;
};

#define CREDENTIAL_INIT { NULL, NULL, 0, NULL, NULL, NULL }

typedef int (*credential_op_cb)(struct credential *);

struct credential_operation {
    char *name;
    credential_op_cb op;
};

#define CREDENTIAL_OP_END { NULL, NULL }

/* ----------------- Secret Service functions ----------------- */

static char *make_label(struct credential *c)
{
    if (c->port)
        return g_strdup_printf("Git: %s://%s:%hu/%s",
                    c->protocol, c->host, c->port, c->path ? c->path : "");
    else
        return g_strdup_printf("Git: %s://%s/%s",
                    c->protocol, c->host, c->path ? c->path : "");
}

static GHashTable *make_attr_list(struct credential *c)
{
    GHashTable *al = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, g_free);

    if (c->username)
        g_hash_table_insert(al, "user", g_strdup(c->username));
    if (c->protocol)
        g_hash_table_insert(al, "protocol", g_strdup(c->protocol));
    if (c->host)
        g_hash_table_insert(al, "server", g_strdup(c->host));
    if (c->port)
        g_hash_table_insert(al, "port", g_strdup_printf("%hu", c->port));
    if (c->path)
        g_hash_table_insert(al, "object", g_strdup(c->path));

    return al;
}

static int keyring_get(struct credential *c)
{
    SecretService *service = NULL;
    GHashTable *attributes = NULL;
    GError *error = NULL;
    GList *items = NULL;

    if (!c->protocol || !(c->host || c->path))
        return EXIT_FAILURE;

    service = secret_service_get_sync(0, NULL, &error);
    if (error != NULL) {
        g_critical("could not connect to Secret Service: %s", error->message);
        g_error_free(error);
        return EXIT_FAILURE;
    }

    attributes = make_attr_list(c);
    items = secret_service_search_sync(service,
                       SECRET_SCHEMA_COMPAT_NETWORK,
                       attributes,
                       SECRET_SEARCH_LOAD_SECRETS | SECRET_SEARCH_UNLOCK,
                       NULL,
                       &error);
    g_hash_table_unref(attributes);
    if (error != NULL) {
        g_critical("lookup failed: %s", error->message);
        g_error_free(error);
        return EXIT_FAILURE;
    }

    if (items != NULL) {
        SecretItem *item;
        SecretValue *secret;
        const char *s;

        item = items->data;
        secret = secret_item_get_secret(item);
        attributes = secret_item_get_attributes(item);

        s = g_hash_table_lookup(attributes, "user");
        if (s) {
            g_free(c->username);
            c->username = g_strdup(s);
        }

        s = secret_value_get_text(secret);
        if (s) {
            g_free(c->password);
            c->password = g_strdup(s);
        }

        g_hash_table_unref(attributes);
        secret_value_unref(secret);
        g_list_free_full(items, g_object_unref);
    }

    return EXIT_SUCCESS;
}


static int keyring_store(struct credential *c)
{
    char *label = NULL;
    GHashTable *attributes = NULL;
    GError *error = NULL;

    /*
     * Sanity check that what we are storing is actually sensible.
     * In particular, we can't make a URL without a protocol field.
     * Without either a host or pathname (depending on the scheme),
     * we have no primary key. And without a username and password,
     * we are not actually storing a credential.
     */
    if (!c->protocol || !(c->host || c->path) ||
        !c->username || !c->password)
        return EXIT_FAILURE;

    label = make_label(c);
    attributes = make_attr_list(c);
    secret_password_storev_sync(SECRET_SCHEMA_COMPAT_NETWORK,
                    attributes,
                    NULL,
                    label,
                    c->password,
                    NULL,
                    &error);
    g_free(label);
    g_hash_table_unref(attributes);

    if (error != NULL) {
        g_critical("store failed: %s", error->message);
        g_error_free(error);
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

static int keyring_erase(struct credential *c)
{
    GHashTable *attributes = NULL;
    GError *error = NULL;

    /*
     * Sanity check that we actually have something to match
     * against. The input we get is a restrictive pattern,
     * so technically a blank credential means "erase everything".
     * But it is too easy to accidentally send this, since it is equivalent
     * to empty input. So explicitly disallow it, and require that the
     * pattern have some actual content to match.
     */
    if (!c->protocol && !c->host && !c->path && !c->username)
        return EXIT_FAILURE;

    attributes = make_attr_list(c);
    secret_password_clearv_sync(SECRET_SCHEMA_COMPAT_NETWORK,
                    attributes,
                    NULL,
                    &error);
    g_hash_table_unref(attributes);

    if (error != NULL) {
        g_critical("erase failed: %s", error->message);
        g_error_free(error);
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

/*
 * Table with helper operation callbacks, used by generic
 * credential helper main function.
 */
static struct credential_operation const credential_helper_ops[] = {
    { "get",   keyring_get },
    { "store", keyring_store },
    { "erase", keyring_erase },
    CREDENTIAL_OP_END
};

/* ------------------ credential functions ------------------ */

static void credential_init(struct credential *c)
{
    memset(c, 0, sizeof(*c));
}

static void credential_clear(struct credential *c)
{
    g_free(c->protocol);
    g_free(c->host);
    g_free(c->path);
    g_free(c->username);
    g_free(c->password);

    credential_init(c);
}

static int credential_read(struct credential *c)
{
    char *buf;
    size_t line_len;
    char *key;
    char *value;

    key = buf = g_malloc(1024);

    while (fgets(buf, 1024, stdin)) {
        line_len = strlen(buf);

        if (line_len && buf[line_len-1] == '\n')
            buf[--line_len] = '\0';

        if (!line_len)
            break;

        value = strchr(buf, '=');
        if (!value) {
            g_warning("invalid credential line: %s", key);
            g_free(buf);
            return -1;
        }
        *value++ = '\0';

        if (!strcmp(key, "protocol")) {
            g_free(c->protocol);
            c->protocol = g_strdup(value);
        } else if (!strcmp(key, "host")) {
            g_free(c->host);
            c->host = g_strdup(value);
            value = strrchr(c->host, ':');
            if (value) {
                *value++ = '\0';
                c->port = atoi(value);
            }
        } else if (!strcmp(key, "path")) {
            g_free(c->path);
            c->path = g_strdup(value);
        } else if (!strcmp(key, "username")) {
            g_free(c->username);
            c->username = g_strdup(value);
        } else if (!strcmp(key, "password")) {
            g_free(c->password);
            c->password = g_strdup(value);
            while (*value)
                *value++ = '\0';
        }
        /*
         * Ignore other lines; we don't know what they mean, but
         * this future-proofs us when later versions of git do
         * learn new lines, and the helpers are updated to match.
         */
    }

    g_free(buf);

    return 0;
}

static void credential_write_item(FILE *fp, const char *key, const char *value)
{
    if (!value)
        return;
    fprintf(fp, "%s=%s\n", key, value);
}

static void credential_write(const struct credential *c)
{
    /* only write username/password, if set */
    credential_write_item(stdout, "username", c->username);
    credential_write_item(stdout, "password", c->password);
}

static void usage(const char *name)
{
    struct credential_operation const *try_op = credential_helper_ops;
    const char *basename = strrchr(name, '/');

    basename = (basename) ? basename + 1 : name;
    fprintf(stderr, "usage: %s <", basename);
    while (try_op->name) {
        fprintf(stderr, "%s", (try_op++)->name);
        if (try_op->name)
            fprintf(stderr, "%s", "|");
    }
    fprintf(stderr, "%s", ">\n");
}

int main(int argc, char *argv[])
{
    int ret = EXIT_SUCCESS;

    struct credential_operation const *try_op = credential_helper_ops;
    struct credential cred = CREDENTIAL_INIT;

    if (!argv[1]) {
        usage(argv[0]);
        exit(EXIT_FAILURE);
    }

    g_set_application_name("Git Credential Helper");

    /* lookup operation callback */
    while (try_op->name && strcmp(argv[1], try_op->name))
        try_op++;

    /* unsupported operation given -- ignore silently */
    if (!try_op->name || !try_op->op)
        goto out;

    ret = credential_read(&cred);
    if (ret)
        goto out;

    /* perform credential operation */
    ret = (*try_op->op)(&cred);

    credential_write(&cred);

out:
    credential_clear(&cred);
    return ret;
}