hostfile.h

/* $OpenBSD: hostfile.h,v 1.29 2021/01/26 00:51:30 djm Exp $ */

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */
#ifndef HOSTFILE_H
#define HOSTFILE_H

typedef enum {
    HOST_OK, HOST_NEW, HOST_CHANGED, HOST_REVOKED, HOST_FOUND
}       HostStatus;

typedef enum {
    MRK_ERROR, MRK_NONE, MRK_REVOKE, MRK_CA
}   HostkeyMarker;

struct hostkey_entry {
    char *host;
    char *file;
    u_long line;
    struct sshkey *key;
    HostkeyMarker marker;
    u_int note; /* caller-specific note/flag */
};
struct hostkeys {
    struct hostkey_entry *entries;
    u_int num_entries;
};

struct hostkeys *init_hostkeys(void);
void     load_hostkeys(struct hostkeys *, const char *,
    const char *, u_int);
void     load_hostkeys_file(struct hostkeys *, const char *,
    const char *, FILE *, u_int note);
void     free_hostkeys(struct hostkeys *);

HostStatus check_key_in_hostkeys(struct hostkeys *, struct sshkey *,
    const struct hostkey_entry **);
int  lookup_key_in_hostkeys_by_type(struct hostkeys *, int, int,
    const struct hostkey_entry **);
int  lookup_marker_in_hostkeys(struct hostkeys *, int);

int  hostfile_read_key(char **, u_int *, struct sshkey *);
int  add_host_to_hostfile(const char *, const char *,
    const struct sshkey *, int);

int  hostfile_replace_entries(const char *filename,
    const char *host, const char *ip, struct sshkey **keys, size_t nkeys,
    int store_hash, int quiet, int hash_alg);

#define HASH_MAGIC  "|1|"
#define HASH_DELIM  '|'

#define CA_MARKER   "@cert-authority"
#define REVOKE_MARKER   "@revoked"

char    *host_hash(const char *, const char *, u_int);

/*
 * Iterate through a hostkeys file, optionally parsing keys and matching
 * hostnames. Allows access to the raw keyfile lines to allow
 * streaming edits to the file to take place.
 */
#define HKF_WANT_MATCH      (1) /* return only matching hosts/addrs */
#define HKF_WANT_PARSE_KEY  (1<<1)  /* need key parsed */

#define HKF_STATUS_OK       0   /* Line parsed, didn't match host */
#define HKF_STATUS_INVALID  1   /* line had parse error */
#define HKF_STATUS_COMMENT  2   /* valid line contained no key */
#define HKF_STATUS_MATCHED  3   /* hostname or IP matched */

#define HKF_MATCH_HOST      (1) /* hostname matched */
#define HKF_MATCH_IP        (1<<1)  /* address matched */
#define HKF_MATCH_HOST_HASHED   (1<<2)  /* hostname was hashed */
#define HKF_MATCH_IP_HASHED (1<<3)  /* address was hashed */
/* XXX HKF_MATCH_KEY_TYPE? */

/*
 * The callback function receives this as an argument for each matching 
 * hostkey line. The callback may "steal" the 'key' field by setting it to NULL.
 * If a parse error occurred, then "hosts" and subsequent options may be NULL.
 */
struct hostkey_foreach_line {
    const char *path; /* Path of file */
    u_long linenum; /* Line number */
    u_int status;   /* One of HKF_STATUS_* */
    u_int match;    /* Zero or more of HKF_MATCH_* OR'd together */
    char *line; /* Entire key line; mutable by callback */
    int marker; /* CA/revocation markers; indicated by MRK_* value */
    const char *hosts; /* Raw hosts text, may be hashed or list multiple */
    const char *rawkey; /* Text of key and any comment following it */
    int keytype;    /* Type of key; KEY_UNSPEC for invalid/comment lines */
    struct sshkey *key; /* Key, if parsed ok and HKF_WANT_MATCH_HOST set */
    const char *comment; /* Any comment following the key */
    u_int note; /* caller-specified note copied from arguments */
};

/*
 * Callback fires for each line (or matching line if a HKF_WANT_* option
 * is set). The foreach loop will terminate if the callback returns a non-
 * zero exit status.
 */
typedef int hostkeys_foreach_fn(struct hostkey_foreach_line *l, void *ctx);

/* Iterate over a hostkeys file */
int hostkeys_foreach(const char *path,
    hostkeys_foreach_fn *callback, void *ctx,
    const char *host, const char *ip, u_int options, u_int note);
int hostkeys_foreach_file(const char *path, FILE *f,
    hostkeys_foreach_fn *callback, void *ctx,
    const char *host, const char *ip, u_int options, u_int note);

void hostfile_create_user_ssh_dir(const char *, int);

#endif