removed the condition in alpm_db_set_servers since FREELIST is NULL safe

[pacman-ng.git] / lib / libalpm / signing.c

/*
 *  signing.c
 *
 *  Copyright (c) 2008-2012 Pacman Development Team <pacman-dev@archlinux.org>
 *
 *  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/>.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#if HAVE_LIBGPGME
#include <locale.h> /* setlocale() */
#include <gpgme.h>
#include "base64.h"
#endif

/* libalpm */
#include "signing.h"
#include "package.h"
#include "util.h"
#include "log.h"
#include "alpm.h"
#include "handle.h"

#if HAVE_LIBGPGME
#define CHECK_ERR(void) do { \
                if(gpg_err_code(err) != GPG_ERR_NO_ERROR) { goto error; } \
        } while(0)

/**
 * Return a statically allocated validity string based on the GPGME validity
 * code. This is mainly for debug purposes and is not translated.
 * @param validity a validity code returned by GPGME
 * @return a string such as "marginal"
 */
static const char *string_validity(gpgme_validity_t validity)
{
        switch(validity) {
                case GPGME_VALIDITY_UNKNOWN:
                        return "unknown";
                case GPGME_VALIDITY_UNDEFINED:
                        return "undefined";
                case GPGME_VALIDITY_NEVER:
                        return "never";
                case GPGME_VALIDITY_MARGINAL:
                        return "marginal";
                case GPGME_VALIDITY_FULL:
                        return "full";
                case GPGME_VALIDITY_ULTIMATE:
                        return "ultimate";
        }
        return "???";
}

static void sigsum_test_bit(gpgme_sigsum_t sigsum, alpm_list_t **summary,
                gpgme_sigsum_t bit, const char *value)
{
        if(sigsum & bit) {
                *summary = alpm_list_add(*summary, (void *)value);
        }
}

/**
 * Calculate a set of strings to represent the given GPGME signature summary
 * value. This is a bitmask so you may get any number of strings back.
 * @param sigsum a GPGME signature summary bitmask
 * @return the list of signature summary strings
 */
static alpm_list_t *list_sigsum(gpgme_sigsum_t sigsum)
{
        alpm_list_t *summary = NULL;
        /* The docs say this can be a bitmask...not sure I believe it, but we'll code
         * for it anyway and show all possible flags in the returned string. */

        /* The signature is fully valid.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_VALID, "valid");
        /* The signature is good.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_GREEN, "green");
        /* The signature is bad.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_RED, "red");
        /* One key has been revoked.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_REVOKED, "key revoked");
        /* One key has expired.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_EXPIRED, "key expired");
        /* The signature has expired.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_SIG_EXPIRED, "sig expired");
        /* Can't verify: key missing.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_MISSING, "key missing");
        /* CRL not available.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_CRL_MISSING, "crl missing");
        /* Available CRL is too old.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_CRL_TOO_OLD, "crl too old");
        /* A policy was not met.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_BAD_POLICY, "bad policy");
        /* A system error occured.  */
        sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_SYS_ERROR, "sys error");
        /* Fallback case */
        if(!sigsum) {
                summary = alpm_list_add(summary, (void *)"(empty)");
        }
        return summary;
}

/**
 * Initialize the GPGME library.
 * This can be safely called multiple times; however it is not thread-safe.
 * @param handle the context handle
 * @return 0 on success, -1 on error
 */
static int init_gpgme(alpm_handle_t *handle)
{
        static int init = 0;
        const char *version, *sigdir;
        gpgme_error_t err;
        gpgme_engine_info_t enginfo;

        if(init) {
                /* we already successfully initialized the library */
                return 0;
        }

        sigdir = handle->gpgdir;

        if(_alpm_access(handle, sigdir, "pubring.gpg", R_OK)
                        || _alpm_access(handle, sigdir, "trustdb.gpg", R_OK)) {
                handle->pm_errno = ALPM_ERR_NOT_A_FILE;
                _alpm_log(handle, ALPM_LOG_DEBUG, "Signature verification will fail!\n");
                _alpm_log(handle, ALPM_LOG_WARNING,
                                _("Public keyring not found; have you run '%s'?\n"),
                                "pacman-key --init");
        }

        /* calling gpgme_check_version() returns the current version and runs
         * some internal library setup code */
        version = gpgme_check_version(NULL);
        _alpm_log(handle, ALPM_LOG_DEBUG, "GPGME version: %s\n", version);
        gpgme_set_locale(NULL, LC_CTYPE, setlocale(LC_CTYPE, NULL));
#ifdef LC_MESSAGES
        gpgme_set_locale(NULL, LC_MESSAGES, setlocale(LC_MESSAGES, NULL));
#endif
        /* NOTE:
         * The GPGME library installs a SIGPIPE signal handler automatically if
         * the default signal hander is in use. The only time we set a handler
         * for SIGPIPE is in dload.c, and we reset it when we are done. Given that
         * we do this, we can let GPGME do its automagic. However, if we install
         * a library-wide SIGPIPE handler, we will have to be careful.
         */

        /* check for OpenPGP support (should be a no-brainer, but be safe) */
        err = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
        CHECK_ERR();

        /* set and check engine information */
        err = gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP, NULL, sigdir);
        CHECK_ERR();
        err = gpgme_get_engine_info(&enginfo);
        CHECK_ERR();
        _alpm_log(handle, ALPM_LOG_DEBUG, "GPGME engine info: file=%s, home=%s\n",
                        enginfo->file_name, enginfo->home_dir);

        init = 1;
        return 0;

error:
        _alpm_log(handle, ALPM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
        RET_ERR(handle, ALPM_ERR_GPGME, -1);
}

/**
 * Determine if we have a key is known in our local keyring.
 * @param handle the context handle
 * @param fpr the fingerprint key ID to look up
 * @return 1 if key is known, 0 if key is unknown, -1 on error
 */
static int key_in_keychain(alpm_handle_t *handle, const char *fpr)
{
        gpgme_error_t err;
        gpgme_ctx_t ctx;
        gpgme_key_t key;
        int ret = -1;

        memset(&ctx, 0, sizeof(ctx));
        err = gpgme_new(&ctx);
        CHECK_ERR();

        _alpm_log(handle, ALPM_LOG_DEBUG, "looking up key %s locally\n", fpr);

        err = gpgme_get_key(ctx, fpr, &key, 0);
        if(gpg_err_code(err) == GPG_ERR_EOF) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "key lookup failed, unknown key\n");
                ret = 0;
        } else if(gpg_err_code(err) == GPG_ERR_NO_ERROR) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "key lookup success, key exists\n");
                ret = 1;
        } else {
                _alpm_log(handle, ALPM_LOG_DEBUG, "gpg error: %s\n", gpgme_strerror(err));
        }
        gpgme_key_unref(key);

error:
        gpgme_release(ctx);
        return ret;
}

/**
 * Search for a GPG key in a remote location.
 * This requires GPGME to call the gpg binary and have a keyserver previously
 * defined in a gpg.conf configuration file.
 * @param handle the context handle
 * @param fpr the fingerprint key ID to look up
 * @param pgpkey storage location for the given key if found
 * @return 1 on success, 0 on key not found, -1 on error
 */
static int key_search(alpm_handle_t *handle, const char *fpr,
                alpm_pgpkey_t *pgpkey)
{
        gpgme_error_t err;
        gpgme_ctx_t ctx;
        gpgme_keylist_mode_t mode;
        gpgme_key_t key;
        int ret = -1;
        size_t fpr_len;
        char *full_fpr;

        /* gpg2 goes full retard here. For key searches ONLY, we need to prefix the
         * key fingerprint with 0x, or the lookup will fail. */
        fpr_len = strlen(fpr);
        MALLOC(full_fpr, fpr_len + 3, RET_ERR(handle, ALPM_ERR_MEMORY, -1));
        sprintf(full_fpr, "0x%s", fpr);

        memset(&ctx, 0, sizeof(ctx));
        err = gpgme_new(&ctx);
        CHECK_ERR();

        mode = gpgme_get_keylist_mode(ctx);
        /* using LOCAL and EXTERN together doesn't work for GPG 1.X. Ugh. */
        mode &= ~GPGME_KEYLIST_MODE_LOCAL;
        mode |= GPGME_KEYLIST_MODE_EXTERN;
        err = gpgme_set_keylist_mode(ctx, mode);
        CHECK_ERR();

        _alpm_log(handle, ALPM_LOG_DEBUG, "looking up key %s remotely\n", fpr);

        err = gpgme_get_key(ctx, full_fpr, &key, 0);
        if(gpg_err_code(err) == GPG_ERR_EOF) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "key lookup failed, unknown key\n");
                /* Try an alternate lookup using the 8 character fingerprint value, since
                 * busted-ass keyservers can't support lookups using subkeys with the full
                 * value as of now. This is why 2012 is not the year of PGP encryption. */
                if(fpr_len > 8) {
                        const char *short_fpr = memcpy(&full_fpr[fpr_len - 8], "0x", 2);
                        _alpm_log(handle, ALPM_LOG_DEBUG,
                                        "looking up key %s remotely\n", short_fpr);
                        err = gpgme_get_key(ctx, short_fpr, &key, 0);
                        if(gpg_err_code(err) == GPG_ERR_EOF) {
                                _alpm_log(handle, ALPM_LOG_DEBUG, "key lookup failed, unknown key\n");
                                ret = 0;
                        }
                } else {
                        ret = 0;
                }
        }

        if(gpg_err_code(err) != GPG_ERR_NO_ERROR) {
                goto error;
        }

        /* should only get here if key actually exists */
        pgpkey->data = key;
        if(key->subkeys->fpr) {
                pgpkey->fingerprint = key->subkeys->fpr;
        } else if(key->subkeys->keyid) {
                pgpkey->fingerprint = key->subkeys->keyid;
        }
        pgpkey->uid = key->uids->uid;
        pgpkey->name = key->uids->name;
        pgpkey->email = key->uids->email;
        pgpkey->created = key->subkeys->timestamp;
        pgpkey->expires = key->subkeys->expires;
        pgpkey->length = key->subkeys->length;
        pgpkey->revoked = key->subkeys->revoked;

        switch (key->subkeys->pubkey_algo) {
                case GPGME_PK_RSA:
                case GPGME_PK_RSA_E:
                case GPGME_PK_RSA_S:
                        pgpkey->pubkey_algo = 'R';
                        break;

                case GPGME_PK_DSA:
                        pgpkey->pubkey_algo = 'D';
                        break;

                case GPGME_PK_ELG_E:
                case GPGME_PK_ELG:
                case GPGME_PK_ECDSA:
                case GPGME_PK_ECDH:
                        pgpkey->pubkey_algo = 'E';
                        break;
        }

        ret = 1;

error:
        if(ret != 1) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "gpg error: %s\n", gpgme_strerror(err));
        }
        free(full_fpr);
        gpgme_release(ctx);
        return ret;
}

/**
 * Import a key into the local keyring.
 * @param handle the context handle
 * @param key the key to import, likely retrieved from #key_search
 * @return 0 on success, -1 on error
 */
static int key_import(alpm_handle_t *handle, alpm_pgpkey_t *key)
{
        gpgme_error_t err;
        gpgme_ctx_t ctx;
        gpgme_key_t keys[2];
        gpgme_import_result_t result;
        int ret = -1;

        if(_alpm_access(handle, handle->gpgdir, "pubring.gpg", W_OK)) {
                /* no chance of import succeeding if pubring isn't writable */
                _alpm_log(handle, ALPM_LOG_ERROR, _("keyring is not writable\n"));
                return -1;
        }

        memset(&ctx, 0, sizeof(ctx));
        err = gpgme_new(&ctx);
        CHECK_ERR();

        _alpm_log(handle, ALPM_LOG_DEBUG, "importing key\n");

        keys[0] = key->data;
        keys[1] = NULL;
        err = gpgme_op_import_keys(ctx, keys);
        CHECK_ERR();
        result = gpgme_op_import_result(ctx);
        CHECK_ERR();
        /* we know we tried to import exactly one key, so check for this */
        if(result->considered != 1 || !result->imports) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "could not import key, 0 results\n");
                ret = -1;
        } else if(result->imports->result != GPG_ERR_NO_ERROR) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "gpg error: %s\n", gpgme_strerror(err));
                ret = -1;
        } else {
                ret = 0;
        }

error:
        gpgme_release(ctx);
        return ret;
}

/**
 * Decode a loaded signature in base64 form.
 * @param base64_data the signature to attempt to decode
 * @param data the decoded data; must be freed by the caller
 * @param data_len the length of the returned data
 * @return 0 on success, -1 on failure to properly decode
 */
static int decode_signature(const char *base64_data,
                unsigned char **data, size_t *data_len) {
        size_t len = strlen(base64_data);
        unsigned char *usline = (unsigned char *)base64_data;
        /* reasonable allocation of expected length is 3/4 of encoded length */
        size_t destlen = len * 3 / 4;
        MALLOC(*data, destlen, goto error);
        if(base64_decode(*data, &destlen, usline, len)) {
                free(*data);
                goto error;
        }
        *data_len = destlen;
        return 0;

error:
        *data = NULL;
        *data_len = 0;
        return -1;
}

/**
 * Check the PGP signature for the given file path.
 * If base64_sig is provided, it will be used as the signature data after
 * decoding. If base64_sig is NULL, expect a signature file next to path
 * (e.g. "%s.sig").
 *
 * The return value will be 0 if nothing abnormal happened during the signature
 * check, and -1 if an error occurred while checking signatures or if a
 * signature could not be found; pm_errno will be set. Note that "abnormal"
 * does not include a failed signature; the value in siglist should be checked
 * to determine if the signature(s) are good.
 * @param handle the context handle
 * @param path the full path to a file
 * @param base64_sig optional PGP signature data in base64 encoding
 * @param siglist a pointer to storage for signature results
 * @return 0 in normal cases, -1 if the something failed in the check process
 */
int _alpm_gpgme_checksig(alpm_handle_t *handle, const char *path,
                const char *base64_sig, alpm_siglist_t *siglist)
{
        int ret = -1, sigcount;
        gpgme_error_t err = 0;
        gpgme_ctx_t ctx;
        gpgme_data_t filedata, sigdata;
        gpgme_verify_result_t verify_result;
        gpgme_signature_t gpgsig;
        char *sigpath = NULL;
        unsigned char *decoded_sigdata = NULL;
        FILE *file = NULL, *sigfile = NULL;

        if(!path || _alpm_access(handle, NULL, path, R_OK) != 0) {
                RET_ERR(handle, ALPM_ERR_NOT_A_FILE, -1);
        }

        if(!siglist) {
                RET_ERR(handle, ALPM_ERR_WRONG_ARGS, -1);
        }
        siglist->count = 0;

        if(!base64_sig) {
                sigpath = _alpm_sigpath(handle, path);
                if(_alpm_access(handle, NULL, sigpath, R_OK) != 0
                                || (sigfile = fopen(sigpath, "rb")) == NULL) {
                        _alpm_log(handle, ALPM_LOG_DEBUG, "sig path %s could not be opened\n",
                                        sigpath);
                        handle->pm_errno = ALPM_ERR_SIG_MISSING;
                        goto error;
                }
        }

        /* does the file we are verifying exist? */
        file = fopen(path, "rb");
        if(file == NULL) {
                handle->pm_errno = ALPM_ERR_NOT_A_FILE;
                goto error;
        }

        if(init_gpgme(handle)) {
                /* pm_errno was set in gpgme_init() */
                goto error;
        }

        _alpm_log(handle, ALPM_LOG_DEBUG, "checking signature for %s\n", path);

        memset(&ctx, 0, sizeof(ctx));
        memset(&sigdata, 0, sizeof(sigdata));
        memset(&filedata, 0, sizeof(filedata));

        err = gpgme_new(&ctx);
        CHECK_ERR();

        /* create our necessary data objects to verify the signature */
        err = gpgme_data_new_from_stream(&filedata, file);
        CHECK_ERR();

        /* next create data object for the signature */
        if(base64_sig) {
                /* memory-based, we loaded it from a sync DB */
                size_t data_len;
                int decode_ret = decode_signature(base64_sig,
                                &decoded_sigdata, &data_len);
                if(decode_ret) {
                        handle->pm_errno = ALPM_ERR_SIG_INVALID;
                        goto gpg_error;
                }
                err = gpgme_data_new_from_mem(&sigdata,
                                (char *)decoded_sigdata, data_len, 0);
        } else {
                /* file-based, it is on disk */
                err = gpgme_data_new_from_stream(&sigdata, sigfile);
        }
        CHECK_ERR();

        /* here's where the magic happens */
        err = gpgme_op_verify(ctx, sigdata, filedata, NULL);
        CHECK_ERR();
        verify_result = gpgme_op_verify_result(ctx);
        CHECK_ERR();
        if(!verify_result || !verify_result->signatures) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "no signatures returned\n");
                handle->pm_errno = ALPM_ERR_SIG_MISSING;
                goto gpg_error;
        }
        for(gpgsig = verify_result->signatures, sigcount = 0;
                        gpgsig; gpgsig = gpgsig->next, sigcount++);
        _alpm_log(handle, ALPM_LOG_DEBUG, "%d signatures returned\n", sigcount);

        CALLOC(siglist->results, sigcount, sizeof(alpm_sigresult_t),
                        handle->pm_errno = ALPM_ERR_MEMORY; goto gpg_error);
        siglist->count = sigcount;

        for(gpgsig = verify_result->signatures, sigcount = 0; gpgsig;
                        gpgsig = gpgsig->next, sigcount++) {
                alpm_list_t *summary_list, *summary;
                alpm_sigstatus_t status;
                alpm_sigvalidity_t validity;
                gpgme_key_t key;
                alpm_sigresult_t *result;

                _alpm_log(handle, ALPM_LOG_DEBUG, "fingerprint: %s\n", gpgsig->fpr);
                summary_list = list_sigsum(gpgsig->summary);
                for(summary = summary_list; summary; summary = summary->next) {
                        _alpm_log(handle, ALPM_LOG_DEBUG, "summary: %s\n", (const char *)summary->data);
                }
                alpm_list_free(summary_list);
                _alpm_log(handle, ALPM_LOG_DEBUG, "status: %s\n", gpgme_strerror(gpgsig->status));
                _alpm_log(handle, ALPM_LOG_DEBUG, "timestamp: %lu\n", gpgsig->timestamp);
                _alpm_log(handle, ALPM_LOG_DEBUG, "exp_timestamp: %lu\n", gpgsig->exp_timestamp);
                _alpm_log(handle, ALPM_LOG_DEBUG, "validity: %s; reason: %s\n",
                                string_validity(gpgsig->validity),
                                gpgme_strerror(gpgsig->validity_reason));

                result = siglist->results + sigcount;
                err = gpgme_get_key(ctx, gpgsig->fpr, &key, 0);
                if(gpg_err_code(err) == GPG_ERR_EOF) {
                        _alpm_log(handle, ALPM_LOG_DEBUG, "key lookup failed, unknown key\n");
                        err = GPG_ERR_NO_ERROR;
                        /* we dupe the fpr in this case since we have no key to point at */
                        STRDUP(result->key.fingerprint, gpgsig->fpr,
                                        handle->pm_errno = ALPM_ERR_MEMORY; goto gpg_error);
                } else {
                        CHECK_ERR();
                        if(key->uids) {
                                result->key.data = key;
                                result->key.fingerprint = key->subkeys->fpr;
                                result->key.uid = key->uids->uid;
                                result->key.name = key->uids->name;
                                result->key.email = key->uids->email;
                                result->key.created = key->subkeys->timestamp;
                                result->key.expires = key->subkeys->expires;
                                _alpm_log(handle, ALPM_LOG_DEBUG,
                                                "key: %s, %s, owner_trust %s, disabled %d\n",
                                                key->subkeys->fpr, key->uids->uid,
                                                string_validity(key->owner_trust), key->disabled);
                        }
                }

                switch(gpg_err_code(gpgsig->status)) {
                        /* good cases */
                        case GPG_ERR_NO_ERROR:
                                status = ALPM_SIGSTATUS_VALID;
                                break;
                        case GPG_ERR_KEY_EXPIRED:
                                status = ALPM_SIGSTATUS_KEY_EXPIRED;
                                break;
                        /* bad cases */
                        case GPG_ERR_SIG_EXPIRED:
                                status = ALPM_SIGSTATUS_SIG_EXPIRED;
                                break;
                        case GPG_ERR_NO_PUBKEY:
                                status = ALPM_SIGSTATUS_KEY_UNKNOWN;
                                break;
                        case GPG_ERR_BAD_SIGNATURE:
                        default:
                                status = ALPM_SIGSTATUS_INVALID;
                                break;
                }
                /* special case: key disabled is not returned in above status code */
                if(result->key.data && key->disabled) {
                        status = ALPM_SIGSTATUS_KEY_DISABLED;
                }

                switch(gpgsig->validity) {
                        case GPGME_VALIDITY_ULTIMATE:
                        case GPGME_VALIDITY_FULL:
                                validity = ALPM_SIGVALIDITY_FULL;
                                break;
                        case GPGME_VALIDITY_MARGINAL:
                                validity = ALPM_SIGVALIDITY_MARGINAL;
                                break;
                        case GPGME_VALIDITY_NEVER:
                                validity = ALPM_SIGVALIDITY_NEVER;
                                break;
                        case GPGME_VALIDITY_UNKNOWN:
                        case GPGME_VALIDITY_UNDEFINED:
                        default:
                                validity = ALPM_SIGVALIDITY_UNKNOWN;
                                break;
                }

                result->status = status;
                result->validity = validity;
        }

        ret = 0;

gpg_error:
        gpgme_data_release(sigdata);
        gpgme_data_release(filedata);
        gpgme_release(ctx);

error:
        if(sigfile) {
                fclose(sigfile);
        }
        if(file) {
                fclose(file);
        }
        FREE(sigpath);
        FREE(decoded_sigdata);
        if(gpg_err_code(err) != GPG_ERR_NO_ERROR) {
                _alpm_log(handle, ALPM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
                RET_ERR(handle, ALPM_ERR_GPGME, -1);
        }
        return ret;
}

#else  /* HAVE_LIBGPGME */
static int key_in_keychain(alpm_handle_t UNUSED *handle, const char UNUSED *fpr)
{
        return -1;
}
int _alpm_gpgme_checksig(alpm_handle_t UNUSED *handle, const char UNUSED *path,
                const char UNUSED *base64_sig, alpm_siglist_t UNUSED *siglist)
{
        return -1;
}
#endif /* HAVE_LIBGPGME */

/**
 * Form a signature path given a file path.
 * Caller must free the result.
 * @param handle the context handle
 * @param path the full path to a file
 * @return the path with '.sig' appended, NULL on errors
 */
char *_alpm_sigpath(alpm_handle_t *handle, const char *path)
{
        char *sigpath;
        size_t len;

        if(!path) {
                return NULL;
        }
        len = strlen(path) + 5;
        CALLOC(sigpath, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
        sprintf(sigpath, "%s.sig", path);
        return sigpath;
}

/**
 * Helper for checking the PGP signature for the given file path.
 * This wraps #_alpm_gpgme_checksig in a slightly friendlier manner to simplify
 * handling of optional signatures and marginal/unknown trust levels and
 * handling the correct error code return values.
 * @param handle the context handle
 * @param path the full path to a file
 * @param base64_sig optional PGP signature data in base64 encoding
 * @param optional whether signatures are optional (e.g., missing OK)
 * @param marginal whether signatures with marginal trust are acceptable
 * @param unknown whether signatures with unknown trust are acceptable
 * @param sigdata a pointer to storage for signature results
 * @return 0 on success, -1 on error (consult pm_errno or sigdata)
 */
int _alpm_check_pgp_helper(alpm_handle_t *handle, const char *path,
                const char *base64_sig, int optional, int marginal, int unknown,
                alpm_siglist_t **sigdata)
{
        alpm_siglist_t *siglist;
        int ret;

        CALLOC(siglist, 1, sizeof(alpm_siglist_t),
                        RET_ERR(handle, ALPM_ERR_MEMORY, -1));

        ret = _alpm_gpgme_checksig(handle, path, base64_sig, siglist);
        if(ret && handle->pm_errno == ALPM_ERR_SIG_MISSING) {
                if(optional) {
                        _alpm_log(handle, ALPM_LOG_DEBUG, "missing optional signature\n");
                        handle->pm_errno = 0;
                        ret = 0;
                } else {
                        _alpm_log(handle, ALPM_LOG_DEBUG, "missing required signature\n");
                        /* ret will already be -1 */
                }
        } else if(ret) {
                _alpm_log(handle, ALPM_LOG_DEBUG, "signature check failed\n");
                /* ret will already be -1 */
        } else {
                size_t num;
                for(num = 0; !ret && num < siglist->count; num++) {
                        switch(siglist->results[num].status) {
                                case ALPM_SIGSTATUS_VALID:
                                case ALPM_SIGSTATUS_KEY_EXPIRED:
                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature is valid\n");
                                        switch(siglist->results[num].validity) {
                                                case ALPM_SIGVALIDITY_FULL:
                                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature is fully trusted\n");
                                                        break;
                                                case ALPM_SIGVALIDITY_MARGINAL:
                                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature is marginal trust\n");
                                                        if(!marginal) {
                                                                ret = -1;
                                                        }
                                                        break;
                                                case ALPM_SIGVALIDITY_UNKNOWN:
                                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature is unknown trust\n");
                                                        if(!unknown) {
                                                                ret = -1;
                                                        }
                                                        break;
                                                case ALPM_SIGVALIDITY_NEVER:
                                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature should never be trusted\n");
                                                        ret = -1;
                                                        break;
                                        }
                                        break;
                                case ALPM_SIGSTATUS_SIG_EXPIRED:
                                case ALPM_SIGSTATUS_KEY_UNKNOWN:
                                case ALPM_SIGSTATUS_KEY_DISABLED:
                                case ALPM_SIGSTATUS_INVALID:
                                        _alpm_log(handle, ALPM_LOG_DEBUG, "signature is not valid\n");
                                        ret = -1;
                                        break;
                        }
                }
        }

        if(sigdata) {
                *sigdata = siglist;
        } else {
                alpm_siglist_cleanup(siglist);
                free(siglist);
        }

        return ret;
}

/**
 * Examine a signature result list and take any appropriate or necessary
 * actions. This may include asking the user to import a key or simply printing
 * helpful failure messages so the user can take action out of band.
 * @param handle the context handle
 * @param identifier a friendly name for the signed resource; usually a
 * database or package name
 * @param siglist a pointer to storage for signature results
 * @param optional whether signatures are optional (e.g., missing OK)
 * @param marginal whether signatures with marginal trust are acceptable
 * @param unknown whether signatures with unknown trust are acceptable
 * @return 0 if all signatures are OK, -1 on errors, 1 if we should retry the
 * validation process
 */
int _alpm_process_siglist(alpm_handle_t *handle, const char *identifier,
                alpm_siglist_t *siglist, int optional, int marginal, int unknown)
{
        size_t i;
        int retry = 0;

        if(!optional && siglist->count == 0) {
                _alpm_log(handle, ALPM_LOG_ERROR,
                                _("%s: missing required signature\n"), identifier);
        }

        for(i = 0; i < siglist->count; i++) {
                alpm_sigresult_t *result = siglist->results + i;
                const char *name = result->key.uid ? result->key.uid : result->key.fingerprint;
                switch(result->status) {
                        case ALPM_SIGSTATUS_VALID:
                        case ALPM_SIGSTATUS_KEY_EXPIRED:
                                switch(result->validity) {
                                        case ALPM_SIGVALIDITY_FULL:
                                                break;
                                        case ALPM_SIGVALIDITY_MARGINAL:
                                                if(!marginal) {
                                                        _alpm_log(handle, ALPM_LOG_ERROR,
                                                                        _("%s: signature from \"%s\" is marginal trust\n"),
                                                                        identifier, name);
                                                        /* QUESTION(handle, ALPM_QUESTION_EDIT_KEY_TRUST, &result->key, NULL, NULL, &answer); */
                                                }
                                                break;
                                        case ALPM_SIGVALIDITY_UNKNOWN:
                                                if(!unknown) {
                                                        _alpm_log(handle, ALPM_LOG_ERROR,
                                                                        _("%s: signature from \"%s\" is unknown trust\n"),
                                                                        identifier, name);
                                                        /* QUESTION(handle, ALPM_QUESTION_EDIT_KEY_TRUST, &result->key, NULL, NULL, &answer); */
                                                }
                                                break;
                                        case ALPM_SIGVALIDITY_NEVER:
                                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                                _("%s: signature from \"%s\" should never be trusted\n"),
                                                                identifier, name);
                                                break;
                                }
                                break;
                        case ALPM_SIGSTATUS_KEY_UNKNOWN:
                                /* ensure this key is still actually unknown; we may have imported it
                                 * on an earlier call to this function. */
                                if(key_in_keychain(handle, result->key.fingerprint) == 1) {
                                        break;
                                }
                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                _("%s: key \"%s\" is unknown\n"), identifier, name);
#ifdef HAVE_LIBGPGME
                                {
                                        int answer = 0;
                                        alpm_pgpkey_t fetch_key;
                                        memset(&fetch_key, 0, sizeof(fetch_key));

                                        if(key_search(handle, result->key.fingerprint, &fetch_key) == 1) {
                                                _alpm_log(handle, ALPM_LOG_DEBUG,
                                                                "unknown key, found %s on keyserver\n", fetch_key.uid);
                                                if(!_alpm_access(handle, handle->gpgdir, "pubring.gpg", W_OK)) {
                                                        QUESTION(handle, ALPM_QUESTION_IMPORT_KEY,
                                                                        &fetch_key, NULL, NULL, &answer);
                                                        if(answer) {
                                                                if(key_import(handle, &fetch_key) == 0) {
                                                                        retry = 1;
                                                                } else {
                                                                        _alpm_log(handle, ALPM_LOG_ERROR,
                                                                                        _("key \"%s\" could not be imported\n"), fetch_key.uid);
                                                                }
                                                        }
                                                } else {
                                                        /* keyring directory was not writable, so we don't even try */
                                                        _alpm_log(handle, ALPM_LOG_WARNING,
                                                                        _("key %s, \"%s\" found on keyserver, keyring is not writable\n"),
                                                                        fetch_key.fingerprint, fetch_key.uid);
                                                }
                                        } else {
                                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                                _("key \"%s\" could not be looked up remotely\n"), name);
                                        }
                                        gpgme_key_unref(fetch_key.data);
                                }
#endif
                                break;
                        case ALPM_SIGSTATUS_KEY_DISABLED:
                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                _("%s: key \"%s\" is disabled\n"), identifier, name);
                                break;
                        case ALPM_SIGSTATUS_SIG_EXPIRED:
                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                _("%s: signature from \"%s\" is expired\n"), identifier, name);
                                break;
                        case ALPM_SIGSTATUS_INVALID:
                                _alpm_log(handle, ALPM_LOG_ERROR,
                                                _("%s: signature from \"%s\" is invalid\n"),
                                                identifier, name);
                                break;
                }
        }

        return retry;
}

/**
 * Check the PGP signature for the given package file.
 * @param pkg the package to check
 * @param siglist a pointer to storage for signature results
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occurred)
 */
int SYMEXPORT alpm_pkg_check_pgp_signature(alpm_pkg_t *pkg,
                alpm_siglist_t *siglist)
{
        ASSERT(pkg != NULL, return -1);
        ASSERT(siglist != NULL, RET_ERR(pkg->handle, ALPM_ERR_WRONG_ARGS, -1));
        pkg->handle->pm_errno = 0;

        return _alpm_gpgme_checksig(pkg->handle, pkg->filename,
                        pkg->base64_sig, siglist);
}

/**
 * Check the PGP signature for the given database.
 * @param db the database to check
 * @param siglist a pointer to storage for signature results
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occurred)
 */
int SYMEXPORT alpm_db_check_pgp_signature(alpm_db_t *db,
                alpm_siglist_t *siglist)
{
        ASSERT(db != NULL, return -1);
        ASSERT(siglist != NULL, RET_ERR(db->handle, ALPM_ERR_WRONG_ARGS, -1));
        db->handle->pm_errno = 0;

        return _alpm_gpgme_checksig(db->handle, _alpm_db_path(db), NULL, siglist);
}

/**
 * Clean up and free a signature result list.
 * Note that this does not free the siglist object itself in case that
 * was allocated on the stack; this is the responsibility of the caller.
 * @param siglist a pointer to storage for signature results
 * @return 0 on success, -1 on error
 */
int SYMEXPORT alpm_siglist_cleanup(alpm_siglist_t *siglist)
{
        ASSERT(siglist != NULL, return -1);
        size_t num;
        for(num = 0; num < siglist->count; num++) {
                alpm_sigresult_t *result = siglist->results + num;
                if(result->key.data) {
#if HAVE_LIBGPGME
                        gpgme_key_unref(result->key.data);
#endif
                } else {
                        free(result->key.fingerprint);
                }
        }
        if(siglist->count) {
                free(siglist->results);
        }
        siglist->results = NULL;
        siglist->count = 0;
        return 0;
}

/* vim: set ts=2 sw=2 noet: */