The second batch

[alt-git.git] / credential.c

#include "git-compat-util.h"
#include "abspath.h"
#include "config.h"
#include "credential.h"
#include "gettext.h"
#include "string-list.h"
#include "run-command.h"
#include "url.h"
#include "prompt.h"
#include "sigchain.h"
#include "strbuf.h"
#include "urlmatch.h"
#include "git-compat-util.h"

void credential_init(struct credential *c)
{
        struct credential blank = CREDENTIAL_INIT;
        memcpy(c, &blank, sizeof(*c));
}

void credential_clear(struct credential *c)
{
        free(c->protocol);
        free(c->host);
        free(c->path);
        free(c->username);
        free(c->password);
        free(c->credential);
        free(c->oauth_refresh_token);
        free(c->authtype);
        string_list_clear(&c->helpers, 0);
        strvec_clear(&c->wwwauth_headers);
        strvec_clear(&c->state_headers);
        strvec_clear(&c->state_headers_to_send);

        credential_init(c);
}

void credential_next_state(struct credential *c)
{
        strvec_clear(&c->state_headers_to_send);
        SWAP(c->state_headers, c->state_headers_to_send);
}

void credential_clear_secrets(struct credential *c)
{
        FREE_AND_NULL(c->password);
        FREE_AND_NULL(c->credential);
}

static void credential_set_capability(struct credential_capability *capa,
                                      enum credential_op_type op_type)
{
        switch (op_type) {
        case CREDENTIAL_OP_INITIAL:
                capa->request_initial = 1;
                break;
        case CREDENTIAL_OP_HELPER:
                capa->request_helper = 1;
                break;
        case CREDENTIAL_OP_RESPONSE:
                capa->response = 1;
                break;
        }
}


void credential_set_all_capabilities(struct credential *c,
                                     enum credential_op_type op_type)
{
        credential_set_capability(&c->capa_authtype, op_type);
        credential_set_capability(&c->capa_state, op_type);
}

static void announce_one(struct credential_capability *cc, const char *name, FILE *fp) {
        if (cc->request_initial)
                fprintf(fp, "capability %s\n", name);
}

void credential_announce_capabilities(struct credential *c, FILE *fp) {
        fprintf(fp, "version 0\n");
        announce_one(&c->capa_authtype, "authtype", fp);
        announce_one(&c->capa_state, "state", fp);
}

int credential_match(const struct credential *want,
                     const struct credential *have, int match_password)
{
#define CHECK(x) (!want->x || (have->x && !strcmp(want->x, have->x)))
        return CHECK(protocol) &&
               CHECK(host) &&
               CHECK(path) &&
               CHECK(username) &&
               (!match_password || CHECK(password)) &&
               (!match_password || CHECK(credential));
#undef CHECK
}


static int credential_from_potentially_partial_url(struct credential *c,
                                                   const char *url);

static int credential_config_callback(const char *var, const char *value,
                                      const struct config_context *ctx UNUSED,
                                      void *data)
{
        struct credential *c = data;
        const char *key;

        if (!skip_prefix(var, "credential.", &key))
                return 0;

        if (!value)
                return config_error_nonbool(var);

        if (!strcmp(key, "helper")) {
                if (*value)
                        string_list_append(&c->helpers, value);
                else
                        string_list_clear(&c->helpers, 0);
        } else if (!strcmp(key, "username")) {
                if (!c->username_from_proto) {
                        free(c->username);
                        c->username = xstrdup(value);
                }
        }
        else if (!strcmp(key, "usehttppath"))
                c->use_http_path = git_config_bool(var, value);

        return 0;
}

static int proto_is_http(const char *s)
{
        if (!s)
                return 0;
        return !strcmp(s, "https") || !strcmp(s, "http");
}

static void credential_describe(struct credential *c, struct strbuf *out);
static void credential_format(struct credential *c, struct strbuf *out);

static int select_all(const struct urlmatch_item *a UNUSED,
                      const struct urlmatch_item *b UNUSED)
{
        return 0;
}

static int match_partial_url(const char *url, void *cb)
{
        struct credential *c = cb;
        struct credential want = CREDENTIAL_INIT;
        int matches = 0;

        if (credential_from_potentially_partial_url(&want, url) < 0)
                warning(_("skipping credential lookup for key: credential.%s"),
                        url);
        else
                matches = credential_match(&want, c, 0);
        credential_clear(&want);

        return matches;
}

static void credential_apply_config(struct credential *c)
{
        char *normalized_url;
        struct urlmatch_config config = URLMATCH_CONFIG_INIT;
        struct strbuf url = STRBUF_INIT;

        if (!c->host)
                die(_("refusing to work with credential missing host field"));
        if (!c->protocol)
                die(_("refusing to work with credential missing protocol field"));

        if (c->configured)
                return;

        config.section = "credential";
        config.key = NULL;
        config.collect_fn = credential_config_callback;
        config.cascade_fn = NULL;
        config.select_fn = select_all;
        config.fallback_match_fn = match_partial_url;
        config.cb = c;

        credential_format(c, &url);
        normalized_url = url_normalize(url.buf, &config.url);

        git_config(urlmatch_config_entry, &config);
        string_list_clear(&config.vars, 1);
        free(normalized_url);
        urlmatch_config_release(&config);
        strbuf_release(&url);

        c->configured = 1;

        if (!c->use_http_path && proto_is_http(c->protocol)) {
                FREE_AND_NULL(c->path);
        }
}

static void credential_describe(struct credential *c, struct strbuf *out)
{
        if (!c->protocol)
                return;
        strbuf_addf(out, "%s://", c->protocol);
        if (c->username && *c->username)
                strbuf_addf(out, "%s@", c->username);
        if (c->host)
                strbuf_addstr(out, c->host);
        if (c->path)
                strbuf_addf(out, "/%s", c->path);
}

static void credential_format(struct credential *c, struct strbuf *out)
{
        if (!c->protocol)
                return;
        strbuf_addf(out, "%s://", c->protocol);
        if (c->username && *c->username) {
                strbuf_add_percentencode(out, c->username, STRBUF_ENCODE_SLASH);
                strbuf_addch(out, '@');
        }
        if (c->host)
                strbuf_addstr(out, c->host);
        if (c->path) {
                strbuf_addch(out, '/');
                strbuf_add_percentencode(out, c->path, 0);
        }
}

static char *credential_ask_one(const char *what, struct credential *c,
                                int flags)
{
        struct strbuf desc = STRBUF_INIT;
        struct strbuf prompt = STRBUF_INIT;
        char *r;

        credential_describe(c, &desc);
        if (desc.len)
                strbuf_addf(&prompt, "%s for '%s': ", what, desc.buf);
        else
                strbuf_addf(&prompt, "%s: ", what);

        r = git_prompt(prompt.buf, flags);

        strbuf_release(&desc);
        strbuf_release(&prompt);
        return xstrdup(r);
}

static void credential_getpass(struct credential *c)
{
        if (!c->username)
                c->username = credential_ask_one("Username", c,
                                                 PROMPT_ASKPASS|PROMPT_ECHO);
        if (!c->password)
                c->password = credential_ask_one("Password", c,
                                                 PROMPT_ASKPASS);
}

int credential_has_capability(const struct credential_capability *capa,
                              enum credential_op_type op_type)
{
        /*
         * We're checking here if each previous step indicated that we had the
         * capability.  If it did, then we want to pass it along; conversely, if
         * it did not, we don't want to report that to our caller.
         */
        switch (op_type) {
        case CREDENTIAL_OP_HELPER:
                return capa->request_initial;
        case CREDENTIAL_OP_RESPONSE:
                return capa->request_initial && capa->request_helper;
        default:
                return 0;
        }
}

int credential_read(struct credential *c, FILE *fp,
                    enum credential_op_type op_type)
{
        struct strbuf line = STRBUF_INIT;

        while (strbuf_getline(&line, fp) != EOF) {
                char *key = line.buf;
                char *value = strchr(key, '=');

                if (!line.len)
                        break;

                if (!value) {
                        warning("invalid credential line: %s", key);
                        strbuf_release(&line);
                        return -1;
                }
                *value++ = '\0';

                if (!strcmp(key, "username")) {
                        free(c->username);
                        c->username = xstrdup(value);
                        c->username_from_proto = 1;
                } else if (!strcmp(key, "password")) {
                        free(c->password);
                        c->password = xstrdup(value);
                } else if (!strcmp(key, "credential")) {
                        free(c->credential);
                        c->credential = xstrdup(value);
                } else if (!strcmp(key, "protocol")) {
                        free(c->protocol);
                        c->protocol = xstrdup(value);
                } else if (!strcmp(key, "host")) {
                        free(c->host);
                        c->host = xstrdup(value);
                } else if (!strcmp(key, "path")) {
                        free(c->path);
                        c->path = xstrdup(value);
                } else if (!strcmp(key, "ephemeral")) {
                        c->ephemeral = !!git_config_bool("ephemeral", value);
                } else if (!strcmp(key, "wwwauth[]")) {
                        strvec_push(&c->wwwauth_headers, value);
                } else if (!strcmp(key, "state[]")) {
                        strvec_push(&c->state_headers, value);
                } else if (!strcmp(key, "capability[]")) {
                        if (!strcmp(value, "authtype"))
                                credential_set_capability(&c->capa_authtype, op_type);
                        else if (!strcmp(value, "state"))
                                credential_set_capability(&c->capa_state, op_type);
                } else if (!strcmp(key, "continue")) {
                        c->multistage = !!git_config_bool("continue", value);
                } else if (!strcmp(key, "password_expiry_utc")) {
                        errno = 0;
                        c->password_expiry_utc = parse_timestamp(value, NULL, 10);
                        if (c->password_expiry_utc == 0 || errno == ERANGE)
                                c->password_expiry_utc = TIME_MAX;
                } else if (!strcmp(key, "oauth_refresh_token")) {
                        free(c->oauth_refresh_token);
                        c->oauth_refresh_token = xstrdup(value);
                } else if (!strcmp(key, "authtype")) {
                        free(c->authtype);
                        c->authtype = xstrdup(value);
                } else if (!strcmp(key, "url")) {
                        credential_from_url(c, value);
                } else if (!strcmp(key, "quit")) {
                        c->quit = !!git_config_bool("quit", value);
                }
                /*
                 * 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.
                 */
        }

        strbuf_release(&line);
        return 0;
}

static void credential_write_item(FILE *fp, const char *key, const char *value,
                                  int required)
{
        if (!value && required)
                BUG("credential value for %s is missing", key);
        if (!value)
                return;
        if (strchr(value, '\n'))
                die("credential value for %s contains newline", key);
        fprintf(fp, "%s=%s\n", key, value);
}

void credential_write(const struct credential *c, FILE *fp,
                      enum credential_op_type op_type)
{
        if (credential_has_capability(&c->capa_authtype, op_type))
                credential_write_item(fp, "capability[]", "authtype", 0);
        if (credential_has_capability(&c->capa_state, op_type))
                credential_write_item(fp, "capability[]", "state", 0);

        if (credential_has_capability(&c->capa_authtype, op_type)) {
                credential_write_item(fp, "authtype", c->authtype, 0);
                credential_write_item(fp, "credential", c->credential, 0);
                if (c->ephemeral)
                        credential_write_item(fp, "ephemeral", "1", 0);
        }
        credential_write_item(fp, "protocol", c->protocol, 1);
        credential_write_item(fp, "host", c->host, 1);
        credential_write_item(fp, "path", c->path, 0);
        credential_write_item(fp, "username", c->username, 0);
        credential_write_item(fp, "password", c->password, 0);
        credential_write_item(fp, "oauth_refresh_token", c->oauth_refresh_token, 0);
        if (c->password_expiry_utc != TIME_MAX) {
                char *s = xstrfmt("%"PRItime, c->password_expiry_utc);
                credential_write_item(fp, "password_expiry_utc", s, 0);
                free(s);
        }
        for (size_t i = 0; i < c->wwwauth_headers.nr; i++)
                credential_write_item(fp, "wwwauth[]", c->wwwauth_headers.v[i], 0);
        if (credential_has_capability(&c->capa_state, op_type)) {
                if (c->multistage)
                        credential_write_item(fp, "continue", "1", 0);
                for (size_t i = 0; i < c->state_headers_to_send.nr; i++)
                        credential_write_item(fp, "state[]", c->state_headers_to_send.v[i], 0);
        }
}

static int run_credential_helper(struct credential *c,
                                 const char *cmd,
                                 int want_output)
{
        struct child_process helper = CHILD_PROCESS_INIT;
        FILE *fp;

        strvec_push(&helper.args, cmd);
        helper.use_shell = 1;
        helper.in = -1;
        if (want_output)
                helper.out = -1;
        else
                helper.no_stdout = 1;

        if (start_command(&helper) < 0)
                return -1;

        fp = xfdopen(helper.in, "w");
        sigchain_push(SIGPIPE, SIG_IGN);
        credential_write(c, fp, want_output ? CREDENTIAL_OP_HELPER : CREDENTIAL_OP_RESPONSE);
        fclose(fp);
        sigchain_pop(SIGPIPE);

        if (want_output) {
                int r;
                fp = xfdopen(helper.out, "r");
                r = credential_read(c, fp, CREDENTIAL_OP_HELPER);
                fclose(fp);
                if (r < 0) {
                        finish_command(&helper);
                        return -1;
                }
        }

        if (finish_command(&helper))
                return -1;
        return 0;
}

static int credential_do(struct credential *c, const char *helper,
                         const char *operation)
{
        struct strbuf cmd = STRBUF_INIT;
        int r;

        if (helper[0] == '!')
                strbuf_addstr(&cmd, helper + 1);
        else if (is_absolute_path(helper))
                strbuf_addstr(&cmd, helper);
        else
                strbuf_addf(&cmd, "git credential-%s", helper);

        strbuf_addf(&cmd, " %s", operation);
        r = run_credential_helper(c, cmd.buf, !strcmp(operation, "get"));

        strbuf_release(&cmd);
        return r;
}

void credential_fill(struct credential *c, int all_capabilities)
{
        int i;

        if ((c->username && c->password) || c->credential)
                return;

        credential_next_state(c);
        c->multistage = 0;

        credential_apply_config(c);
        if (all_capabilities)
                credential_set_all_capabilities(c, CREDENTIAL_OP_INITIAL);

        for (i = 0; i < c->helpers.nr; i++) {
                credential_do(c, c->helpers.items[i].string, "get");
                if (c->password_expiry_utc < time(NULL)) {
                        /* Discard expired password */
                        FREE_AND_NULL(c->password);
                        /* Reset expiry to maintain consistency */
                        c->password_expiry_utc = TIME_MAX;
                }
                if ((c->username && c->password) || c->credential) {
                        strvec_clear(&c->wwwauth_headers);
                        return;
                }
                if (c->quit)
                        die("credential helper '%s' told us to quit",
                            c->helpers.items[i].string);
        }

        credential_getpass(c);
        if (!c->username && !c->password && !c->credential)
                die("unable to get password from user");
}

void credential_approve(struct credential *c)
{
        int i;

        if (c->approved)
                return;
        if (((!c->username || !c->password) && !c->credential) || c->password_expiry_utc < time(NULL))
                return;

        credential_next_state(c);

        credential_apply_config(c);

        for (i = 0; i < c->helpers.nr; i++)
                credential_do(c, c->helpers.items[i].string, "store");
        c->approved = 1;
}

void credential_reject(struct credential *c)
{
        int i;

        credential_next_state(c);

        credential_apply_config(c);

        for (i = 0; i < c->helpers.nr; i++)
                credential_do(c, c->helpers.items[i].string, "erase");

        FREE_AND_NULL(c->username);
        FREE_AND_NULL(c->password);
        FREE_AND_NULL(c->credential);
        FREE_AND_NULL(c->oauth_refresh_token);
        c->password_expiry_utc = TIME_MAX;
        c->approved = 0;
}

static int check_url_component(const char *url, int quiet,
                               const char *name, const char *value)
{
        if (!value)
                return 0;
        if (!strchr(value, '\n'))
                return 0;

        if (!quiet)
                warning(_("url contains a newline in its %s component: %s"),
                        name, url);
        return -1;
}

/*
 * Potentially-partial URLs can, but do not have to, contain
 *
 * - a protocol (or scheme) of the form "<protocol>://"
 *
 * - a host name (the part after the protocol and before the first slash after
 *   that, if any)
 *
 * - a user name and potentially a password (as "<user>[:<password>]@" part of
 *   the host name)
 *
 * - a path (the part after the host name, if any, starting with the slash)
 *
 * Missing parts will be left unset in `struct credential`. Thus, `https://`
 * will have only the `protocol` set, `example.com` only the host name, and
 * `/git` only the path.
 *
 * Note that an empty host name in an otherwise fully-qualified URL (e.g.
 * `cert:///path/to/cert.pem`) will be treated as unset if we expect the URL to
 * be potentially partial, and only then (otherwise, the empty string is used).
 *
 * The credential_from_url() function does not allow partial URLs.
 */
static int credential_from_url_1(struct credential *c, const char *url,
                                 int allow_partial_url, int quiet)
{
        const char *at, *colon, *cp, *slash, *host, *proto_end;

        credential_clear(c);

        /*
         * Match one of:
         *   (1) proto://<host>/...
         *   (2) proto://<user>@<host>/...
         *   (3) proto://<user>:<pass>@<host>/...
         */
        proto_end = strstr(url, "://");
        if (!allow_partial_url && (!proto_end || proto_end == url)) {
                if (!quiet)
                        warning(_("url has no scheme: %s"), url);
                return -1;
        }
        cp = proto_end ? proto_end + 3 : url;
        at = strchr(cp, '@');
        colon = strchr(cp, ':');

        /*
         * A query or fragment marker before the slash ends the host portion.
         * We'll just continue to call this "slash" for simplicity. Notably our
         * "trim leading slashes" part won't skip over this part of the path,
         * but that's what we'd want.
         */
        slash = cp + strcspn(cp, "/?#");

        if (!at || slash <= at) {
                /* Case (1) */
                host = cp;
        }
        else if (!colon || at <= colon) {
                /* Case (2) */
                c->username = url_decode_mem(cp, at - cp);
                if (c->username && *c->username)
                        c->username_from_proto = 1;
                host = at + 1;
        } else {
                /* Case (3) */
                c->username = url_decode_mem(cp, colon - cp);
                if (c->username && *c->username)
                        c->username_from_proto = 1;
                c->password = url_decode_mem(colon + 1, at - (colon + 1));
                host = at + 1;
        }

        if (proto_end && proto_end - url > 0)
                c->protocol = xmemdupz(url, proto_end - url);
        if (!allow_partial_url || slash - host > 0)
                c->host = url_decode_mem(host, slash - host);
        /* Trim leading and trailing slashes from path */
        while (*slash == '/')
                slash++;
        if (*slash) {
                char *p;
                c->path = url_decode(slash);
                p = c->path + strlen(c->path) - 1;
                while (p > c->path && *p == '/')
                        *p-- = '\0';
        }

        if (check_url_component(url, quiet, "username", c->username) < 0 ||
            check_url_component(url, quiet, "password", c->password) < 0 ||
            check_url_component(url, quiet, "protocol", c->protocol) < 0 ||
            check_url_component(url, quiet, "host", c->host) < 0 ||
            check_url_component(url, quiet, "path", c->path) < 0)
                return -1;

        return 0;
}

static int credential_from_potentially_partial_url(struct credential *c,
                                                   const char *url)
{
        return credential_from_url_1(c, url, 1, 0);
}

int credential_from_url_gently(struct credential *c, const char *url, int quiet)
{
        return credential_from_url_1(c, url, 0, quiet);
}

void credential_from_url(struct credential *c, const char *url)
{
        if (credential_from_url_gently(c, url, 0) < 0)
                die(_("credential url cannot be parsed: %s"), url);
}