/*
* libssh2_knownhost_check
*
* Check a host and its associated key against the collection of known hosts.
*
* The typemask is the type/format of the given host name and key
*
* plain - ascii "hostname.domain.tld"
* sha1 - NOT SUPPORTED AS INPUT
* custom - prehashed base64 encoded. Note that this cannot use any salts.
*
* Returns:
*
* LIBSSH2_KNOWNHOST_CHECK_FAILURE
* LIBSSH2_KNOWNHOST_CHECK_NOTFOUND
* LIBSSH2_KNOWNHOST_CHECK_MATCH
* LIBSSH2_KNOWNHOST_CHECK_MISMATCH
*/
LIBSSH2_API int
libssh2_knownhost_check(LIBSSH2_KNOWNHOSTS *hosts,
const char *host, const char *key, size_t keylen,
int typemask,
struct libssh2_knownhost **ext)
{
struct known_host *node = _libssh2_list_first(&hosts->head);
struct known_host *badkey = NULL;
int type = typemask & LIBSSH2_KNOWNHOST_TYPE_MASK;
char *keyalloc = NULL;
int rc = LIBSSH2_KNOWNHOST_CHECK_NOTFOUND;
if(type == LIBSSH2_KNOWNHOST_TYPE_SHA1)
/* we can't work with a sha1 as given input */
return LIBSSH2_KNOWNHOST_CHECK_MISMATCH;
if(!(typemask & LIBSSH2_KNOWNHOST_KEYENC_BASE64)) {
/* we got a raw key input, convert it to base64 for the checks below */
size_t nlen = _libssh2_base64_encode(hosts->session, key, keylen,
&keyalloc);
if(!nlen)
return LIBSSH2_KNOWNHOST_CHECK_FAILURE;
/* make the key point to this */
key = keyalloc;
keylen = nlen;
}
while (node) {
int match = 0;
switch(node->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) {
case LIBSSH2_KNOWNHOST_TYPE_PLAIN:
if(type == LIBSSH2_KNOWNHOST_TYPE_PLAIN)
match = !strcmp(host, node->name);
break;
case LIBSSH2_KNOWNHOST_TYPE_CUSTOM:
if(type == LIBSSH2_KNOWNHOST_TYPE_CUSTOM)
match = !strcmp(host, node->name);
break;
case LIBSSH2_KNOWNHOST_TYPE_SHA1:
if(type == LIBSSH2_KNOWNHOST_TYPE_PLAIN) {
/* when we have the sha1 version stored, we can use a plain
input to produce a hash to compare with the stored hash.
*/
libssh2_hmac_ctx ctx;
unsigned char hash[SHA_DIGEST_LENGTH];
if(SHA_DIGEST_LENGTH != node->name_len) {
/* the name hash length must be the sha1 size or
we can't match it */
break;
}
libssh2_hmac_sha1_init(&ctx, node->salt, node->salt_len);
libssh2_hmac_update(ctx, (unsigned char *)host, strlen(host));
libssh2_hmac_final(ctx, hash);
libssh2_hmac_cleanup(&ctx);
if(!memcmp(hash, node->name, SHA_DIGEST_LENGTH))
/* this is a node we're interested in */
match = 1;
}
break;
default: /* unsupported type */
break;
}
if(match) {
/* host name match, now compare the keys */
if(!strcmp(key, node->key)) {
/* they match! */
*ext = knownhost_to_external(node);
badkey = NULL;
rc = LIBSSH2_KNOWNHOST_CHECK_MATCH;
break;
}
else {
/* remember the first node that had a host match but a failed
key match since we continue our search from here */
if(!badkey)
badkey = node;
}
}
node= _libssh2_list_next(&node->node);
}
if(badkey) {
/* key mismatch */
*ext = knownhost_to_external(badkey);
rc = LIBSSH2_KNOWNHOST_CHECK_MISMATCH;
}
if(keyalloc)
LIBSSH2_FREE(hosts->session, keyalloc);
return rc;
}
/*
* knownhost_writeline()
*
* Ask libssh2 to convert a known host to an output line for storage.
*
* Note that this function returns LIBSSH2_ERROR_BUFFER_TOO_SMALL if the given
* output buffer is too small to hold the desired output. The 'outlen' field
* will then contain the size libssh2 wanted to store, which then is the
* smallest sufficient buffer it would require.
*
*/
static int
knownhost_writeline(LIBSSH2_KNOWNHOSTS *hosts,
struct known_host *node,
char *buf, size_t buflen,
size_t *outlen, int type)
{
int rc = LIBSSH2_ERROR_NONE;
int tindex;
const char *keytypes[4]={
"", /* not used */
"", /* this type has no name in the file */
" ssh-rsa",
" ssh-dss"
};
const char *keytype;
size_t nlen;
/* we only support this single file type for now, bail out on all other
attempts */
if(type != LIBSSH2_KNOWNHOST_FILE_OPENSSH)
return LIBSSH2_ERROR_METHOD_NOT_SUPPORTED;
tindex = (node->typemask & LIBSSH2_KNOWNHOST_KEY_MASK) >>
LIBSSH2_KNOWNHOST_KEY_SHIFT;
/* set the string used in the file */
keytype = keytypes[tindex];
if((node->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) ==
LIBSSH2_KNOWNHOST_TYPE_SHA1) {
char *namealloc;
char *saltalloc;
nlen = _libssh2_base64_encode(hosts->session, node->name,
node->name_len, &namealloc);
if(!nlen)
return LIBSSH2_ERROR_ALLOC;
nlen = _libssh2_base64_encode(hosts->session,
node->salt, node->salt_len,
&saltalloc);
if(!nlen) {
free(namealloc);
return LIBSSH2_ERROR_ALLOC;
}
nlen = strlen(saltalloc) + strlen(namealloc) + strlen(keytype) +
strlen(node->key) + 7; /* |1| + | + ' ' + \n + \0 = 7 */
if(nlen <= buflen)
sprintf(buf, "|1|%s|%s%s %s\n", saltalloc, namealloc, keytype,
node->key);
else
rc = LIBSSH2_ERROR_BUFFER_TOO_SMALL;
free(namealloc);
free(saltalloc);
}
else {
nlen = strlen(node->name) + strlen(keytype) + strlen(node->key) + 3;
/* ' ' + '\n' + \0 = 3 */
if(nlen <= buflen)
/* these types have the plain name */
sprintf(buf, "%s%s %s\n", node->name, keytype, node->key);
else
rc = LIBSSH2_ERROR_BUFFER_TOO_SMALL;
}
/* we report the full length of the data with the trailing zero excluded */
*outlen = nlen-1;
return rc;
}
LIBSSH2_API int
libssh2_knownhost_add(LIBSSH2_KNOWNHOSTS *hosts,
const char *host, const char *salt,
const char *key, size_t keylen,
int typemask, struct libssh2_knownhost **store)
{
struct known_host *entry =
LIBSSH2_ALLOC(hosts->session, sizeof(struct known_host));
size_t hostlen = strlen(host);
int rc = LIBSSH2_ERROR_ALLOC;
char *ptr;
unsigned int ptrlen;
if(!entry)
return rc;
if(!(typemask & LIBSSH2_KNOWNHOST_KEY_MASK))
/* make sure we have a key type set */
return LIBSSH2_ERROR_INVAL;
memset(entry, 0, sizeof(struct known_host));
entry->typemask = typemask;
switch(entry->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) {
case LIBSSH2_KNOWNHOST_TYPE_PLAIN:
case LIBSSH2_KNOWNHOST_TYPE_CUSTOM:
entry->name = LIBSSH2_ALLOC(hosts->session, hostlen+1);
if(!entry)
goto error;
memcpy(entry->name, host, hostlen+1);
break;
case LIBSSH2_KNOWNHOST_TYPE_SHA1:
rc = libssh2_base64_decode(hosts->session, &ptr, &ptrlen,
host, hostlen);
if(rc)
goto error;
entry->name = ptr;
entry->name_len = ptrlen;
rc = libssh2_base64_decode(hosts->session, &ptr, &ptrlen,
salt, strlen(salt));
if(rc)
goto error;
entry->salt = ptr;
entry->salt_len = ptrlen;
break;
default:
rc = LIBSSH2_ERROR_METHOD_NOT_SUPPORTED;
goto error;
}
if(typemask & LIBSSH2_KNOWNHOST_KEYENC_BASE64) {
/* the provided key is base64 encoded already */
if(!keylen)
keylen = strlen(key);
entry->key = LIBSSH2_ALLOC(hosts->session, keylen+1);
if(!entry)
goto error;
memcpy(entry->key, key, keylen+1);
entry->key[keylen]=0; /* force a terminating zero trailer */
}
else {
/* key is raw, we base64 encode it and store it as such */
size_t nlen = _libssh2_base64_encode(hosts->session, key, keylen,
&ptr);
if(!nlen)
goto error;
entry->key = ptr;
}
/* add this new host to the big list of known hosts */
_libssh2_list_add(&hosts->head, &entry->node);
if(store)
*store = knownhost_to_external(entry);
return LIBSSH2_ERROR_NONE;
error:
free_host(hosts->session, entry);
return rc;
}
/*
* knownhost_writeline()
*
* Ask libssh2 to convert a known host to an output line for storage.
*
* Note that this function returns LIBSSH2_ERROR_BUFFER_TOO_SMALL if the given
* output buffer is too small to hold the desired output. The 'outlen' field
* will then contain the size libssh2 wanted to store, which then is the
* smallest sufficient buffer it would require.
*
*/
static int
knownhost_writeline(LIBSSH2_KNOWNHOSTS *hosts,
struct known_host *node,
char *buf, size_t buflen,
size_t *outlen, int type)
{
size_t required_size;
const char *key_type_name;
size_t key_type_len;
/* we only support this single file type for now, bail out on all other
attempts */
if(type != LIBSSH2_KNOWNHOST_FILE_OPENSSH)
return _libssh2_error(hosts->session,
LIBSSH2_ERROR_METHOD_NOT_SUPPORTED,
"Unsupported type of known-host information "
"store");
switch(node->typemask & LIBSSH2_KNOWNHOST_KEY_MASK) {
case LIBSSH2_KNOWNHOST_KEY_RSA1:
key_type_name = NULL;
key_type_len = 0;
break;
case LIBSSH2_KNOWNHOST_KEY_SSHRSA:
key_type_name = "ssh-rsa";
key_type_len = 7;
break;
case LIBSSH2_KNOWNHOST_KEY_SSHDSS:
key_type_name = "ssh-dss";
key_type_len = 7;
break;
case LIBSSH2_KNOWNHOST_KEY_UNKNOWN:
key_type_name = node->key_type_name;
if (key_type_name) {
key_type_len = node->key_type_len;
break;
}
/* otherwise fallback to default and error */
default:
return _libssh2_error(hosts->session,
LIBSSH2_ERROR_METHOD_NOT_SUPPORTED,
"Unsupported type of known-host entry");
}
/* When putting together the host line there are three aspects to consider:
- Hashed (SHA1) or unhashed hostname
- key name or no key name (RSA1)
- comment or no comment
This means there are 2^3 different formats:
("|1|%s|%s %s %s %s\n", salt, hashed_host, key_name, key, comment)
("|1|%s|%s %s %s\n", salt, hashed_host, key_name, key)
("|1|%s|%s %s %s\n", salt, hashed_host, key, comment)
("|1|%s|%s %s\n", salt, hashed_host, key)
("%s %s %s %s\n", host, key_name, key, comment)
("%s %s %s\n", host, key_name, key)
("%s %s %s\n", host, key, comment)
("%s %s\n", host, key)
Even if the buffer is too small, we have to set outlen to the number of
characters the complete line would have taken. We also don't write
anything to the buffer unless we are sure we can write everything to the
buffer. */
required_size = strlen(node->key);
if(key_type_len)
required_size += key_type_len + 1; /* ' ' = 1 */
if(node->comment)
required_size += node->comment_len + 1; /* ' ' = 1 */
if((node->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) ==
LIBSSH2_KNOWNHOST_TYPE_SHA1) {
char *namealloc;
size_t name_base64_len;
char *saltalloc;
size_t salt_base64_len;
name_base64_len = _libssh2_base64_encode(hosts->session, node->name,
node->name_len, &namealloc);
if(!name_base64_len)
return _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for "
"base64-encoded host name");
salt_base64_len = _libssh2_base64_encode(hosts->session,
node->salt, node->salt_len,
&saltalloc);
if(!salt_base64_len) {
LIBSSH2_FREE(hosts->session, namealloc);
return _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for "
"base64-encoded salt");
}
required_size += salt_base64_len + name_base64_len + 7;
/* |1| + | + ' ' + \n + \0 = 7 */
if(required_size <= buflen) {
if(node->comment && key_type_len)
snprintf(buf, buflen, "|1|%s|%s %s %s %s\n", saltalloc,
namealloc, key_type_name, node->key, node->comment);
else if (node->comment)
snprintf(buf, buflen, "|1|%s|%s %s %s\n", saltalloc, namealloc,
node->key, node->comment);
else if (key_type_len)
snprintf(buf, buflen, "|1|%s|%s %s %s\n", saltalloc, namealloc,
key_type_name, node->key);
else
snprintf(buf, buflen, "|1|%s|%s %s\n", saltalloc, namealloc,
node->key);
}
LIBSSH2_FREE(hosts->session, namealloc);
LIBSSH2_FREE(hosts->session, saltalloc);
}
else {
required_size += node->name_len + 3;
/* ' ' + '\n' + \0 = 3 */
if(required_size <= buflen) {
if(node->comment && key_type_len)
snprintf(buf, buflen, "%s %s %s %s\n", node->name,
key_type_name, node->key, node->comment);
else if (node->comment)
snprintf(buf, buflen, "%s %s %s\n", node->name, node->key,
node->comment);
else if (key_type_len)
snprintf(buf, buflen, "%s %s %s\n", node->name, key_type_name,
node->key);
else
snprintf(buf, buflen, "%s %s\n", node->name, node->key);
}
}
/* we report the full length of the data with the trailing zero excluded */
*outlen = required_size-1;
if(required_size <= buflen)
return LIBSSH2_ERROR_NONE;
else
return _libssh2_error(hosts->session, LIBSSH2_ERROR_BUFFER_TOO_SMALL,
"Known-host write buffer too small");
}
/*
* knownhost_check
*
* Check a host and its associated key against the collection of known hosts.
*
* The typemask is the type/format of the given host name and key
*
* plain - ascii "hostname.domain.tld"
* sha1 - NOT SUPPORTED AS INPUT
* custom - prehashed base64 encoded. Note that this cannot use any salts.
*
* Returns:
*
* LIBSSH2_KNOWNHOST_CHECK_FAILURE
* LIBSSH2_KNOWNHOST_CHECK_NOTFOUND
* LIBSSH2_KNOWNHOST_CHECK_MATCH
* LIBSSH2_KNOWNHOST_CHECK_MISMATCH
*/
static int
knownhost_check(LIBSSH2_KNOWNHOSTS *hosts,
const char *hostp, int port,
const char *key, size_t keylen,
int typemask,
struct libssh2_knownhost **ext)
{
struct known_host *node;
struct known_host *badkey = NULL;
int type = typemask & LIBSSH2_KNOWNHOST_TYPE_MASK;
char *keyalloc = NULL;
int rc = LIBSSH2_KNOWNHOST_CHECK_NOTFOUND;
char hostbuff[270]; /* most host names can't be longer than like 256 */
const char *host;
int numcheck; /* number of host combos to check */
int match = 0;
if(type == LIBSSH2_KNOWNHOST_TYPE_SHA1)
/* we can't work with a sha1 as given input */
return LIBSSH2_KNOWNHOST_CHECK_MISMATCH;
/* if a port number is given, check for a '[host]:port' first before the
plain 'host' */
if(port >= 0) {
int len = snprintf(hostbuff, sizeof(hostbuff), "[%s]:%d", hostp, port);
if (len < 0 || len >= (int)sizeof(hostbuff)) {
_libssh2_error(hosts->session,
LIBSSH2_ERROR_BUFFER_TOO_SMALL,
"Known-host write buffer too small");
return LIBSSH2_KNOWNHOST_CHECK_FAILURE;
}
host = hostbuff;
numcheck = 2; /* check both combos, start with this */
}
else {
host = hostp;
numcheck = 1; /* only check this host version */
}
if(!(typemask & LIBSSH2_KNOWNHOST_KEYENC_BASE64)) {
/* we got a raw key input, convert it to base64 for the checks below */
size_t nlen = _libssh2_base64_encode(hosts->session, key, keylen,
&keyalloc);
if(!nlen) {
_libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for base64-encoded "
"key");
return LIBSSH2_KNOWNHOST_CHECK_FAILURE;
}
/* make the key point to this */
key = keyalloc;
}
do {
node = _libssh2_list_first(&hosts->head);
while (node) {
switch(node->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) {
case LIBSSH2_KNOWNHOST_TYPE_PLAIN:
if(type == LIBSSH2_KNOWNHOST_TYPE_PLAIN)
match = !strcmp(host, node->name);
break;
case LIBSSH2_KNOWNHOST_TYPE_CUSTOM:
if(type == LIBSSH2_KNOWNHOST_TYPE_CUSTOM)
match = !strcmp(host, node->name);
break;
case LIBSSH2_KNOWNHOST_TYPE_SHA1:
if(type == LIBSSH2_KNOWNHOST_TYPE_PLAIN) {
/* when we have the sha1 version stored, we can use a
plain input to produce a hash to compare with the
stored hash.
*/
libssh2_hmac_ctx ctx;
unsigned char hash[SHA_DIGEST_LENGTH];
if(SHA_DIGEST_LENGTH != node->name_len) {
/* the name hash length must be the sha1 size or
we can't match it */
break;
}
libssh2_hmac_sha1_init(&ctx, (unsigned char *)node->salt,
node->salt_len);
libssh2_hmac_update(ctx, (unsigned char *)host,
strlen(host));
libssh2_hmac_final(ctx, hash);
libssh2_hmac_cleanup(&ctx);
if(!memcmp(hash, node->name, SHA_DIGEST_LENGTH))
/* this is a node we're interested in */
match = 1;
}
break;
default: /* unsupported type */
break;
}
if(match) {
int host_key_type = typemask & LIBSSH2_KNOWNHOST_KEY_MASK;
int known_key_type =
node->typemask & LIBSSH2_KNOWNHOST_KEY_MASK;
/* match on key type as follows:
- never match on an unknown key type
- if key_type is set to zero, ignore it an match always
- otherwise match when both key types are equal
*/
if ( (host_key_type != LIBSSH2_KNOWNHOST_KEY_UNKNOWN ) &&
( (host_key_type == 0) ||
(host_key_type == known_key_type) ) ) {
/* host name and key type match, now compare the keys */
if(!strcmp(key, node->key)) {
/* they match! */
if (ext)
*ext = knownhost_to_external(node);
badkey = NULL;
rc = LIBSSH2_KNOWNHOST_CHECK_MATCH;
break;
}
else {
/* remember the first node that had a host match but a
failed key match since we continue our search from
here */
if(!badkey)
badkey = node;
}
}
match = 0; /* don't count this as a match anymore */
}
node= _libssh2_list_next(&node->node);
}
host = hostp;
} while(!match && --numcheck);
if(badkey) {
/* key mismatch */
if (ext)
*ext = knownhost_to_external(badkey);
rc = LIBSSH2_KNOWNHOST_CHECK_MISMATCH;
}
if(keyalloc)
LIBSSH2_FREE(hosts->session, keyalloc);
return rc;
}
static int
knownhost_add(LIBSSH2_KNOWNHOSTS *hosts,
const char *host, const char *salt,
const char *key_type_name, size_t key_type_len,
const char *key, size_t keylen,
const char *comment, size_t commentlen,
int typemask, struct libssh2_knownhost **store)
{
struct known_host *entry;
size_t hostlen = strlen(host);
int rc;
char *ptr;
unsigned int ptrlen;
/* make sure we have a key type set */
if(!(typemask & LIBSSH2_KNOWNHOST_KEY_MASK))
return _libssh2_error(hosts->session, LIBSSH2_ERROR_INVAL,
"No key type set");
if(!(entry = LIBSSH2_CALLOC(hosts->session, sizeof(struct known_host))))
return _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for known host "
"entry");
entry->typemask = typemask;
switch(entry->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) {
case LIBSSH2_KNOWNHOST_TYPE_PLAIN:
case LIBSSH2_KNOWNHOST_TYPE_CUSTOM:
entry->name = LIBSSH2_ALLOC(hosts->session, hostlen+1);
if(!entry->name) {
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for host name");
goto error;
}
memcpy(entry->name, host, hostlen+1);
entry->name_len = hostlen;
break;
case LIBSSH2_KNOWNHOST_TYPE_SHA1:
rc = libssh2_base64_decode(hosts->session, &ptr, &ptrlen,
host, hostlen);
if(rc)
goto error;
entry->name = ptr;
entry->name_len = ptrlen;
rc = libssh2_base64_decode(hosts->session, &ptr, &ptrlen,
salt, strlen(salt));
if(rc)
goto error;
entry->salt = ptr;
entry->salt_len = ptrlen;
break;
default:
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_METHOD_NOT_SUPPORTED,
"Unknown host name type");
goto error;
}
if(typemask & LIBSSH2_KNOWNHOST_KEYENC_BASE64) {
/* the provided key is base64 encoded already */
if(!keylen)
keylen = strlen(key);
entry->key = LIBSSH2_ALLOC(hosts->session, keylen+1);
if(!entry->key) {
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for key");
goto error;
}
memcpy(entry->key, key, keylen+1);
entry->key[keylen]=0; /* force a terminating zero trailer */
}
else {
/* key is raw, we base64 encode it and store it as such */
size_t nlen = _libssh2_base64_encode(hosts->session, key, keylen,
&ptr);
if(!nlen) {
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for "
"base64-encoded key");
goto error;
}
entry->key = ptr;
}
if (key_type_name && ((typemask & LIBSSH2_KNOWNHOST_KEY_MASK) ==
LIBSSH2_KNOWNHOST_KEY_UNKNOWN)) {
entry->key_type_name = LIBSSH2_ALLOC(hosts->session, key_type_len+1);
if (!entry->key_type_name) {
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for key type");
goto error;
}
memcpy(entry->key_type_name, key_type_name, key_type_len);
entry->key_type_name[key_type_len]=0;
entry->key_type_len = key_type_len;
}
if (comment) {
entry->comment = LIBSSH2_ALLOC(hosts->session, commentlen+1);
if(!entry->comment) {
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for comment");
goto error;
}
memcpy(entry->comment, comment, commentlen+1);
entry->comment[commentlen]=0; /* force a terminating zero trailer */
entry->comment_len = commentlen;
}
else {
entry->comment = NULL;
}
/* add this new host to the big list of known hosts */
_libssh2_list_add(&hosts->head, &entry->node);
if(store)
*store = knownhost_to_external(entry);
return LIBSSH2_ERROR_NONE;
error:
free_host(hosts->session, entry);
return rc;
}
/*
* knownhost_writeline()
*
* Ask libssh2 to convert a known host to an output line for storage.
*
* Note that this function returns LIBSSH2_ERROR_BUFFER_TOO_SMALL if the given
* output buffer is too small to hold the desired output. The 'outlen' field
* will then contain the size libssh2 wanted to store, which then is the
* smallest sufficient buffer it would require.
*
*/
static int
knownhost_writeline(LIBSSH2_KNOWNHOSTS *hosts,
struct known_host *node,
char *buf, size_t buflen,
size_t *outlen, int type)
{
int rc = LIBSSH2_ERROR_NONE;
int tindex;
const char *keytypes[4]={
"", /* not used */
"", /* this type has no name in the file */
" ssh-rsa",
" ssh-dss"
};
const char *keytype;
size_t nlen;
size_t commentlen = 0;
/* we only support this single file type for now, bail out on all other
attempts */
if(type != LIBSSH2_KNOWNHOST_FILE_OPENSSH)
return _libssh2_error(hosts->session,
LIBSSH2_ERROR_METHOD_NOT_SUPPORTED,
"Unsupported type of known-host information "
"store");
tindex = (node->typemask & LIBSSH2_KNOWNHOST_KEY_MASK) >>
LIBSSH2_KNOWNHOST_KEY_SHIFT;
/* set the string used in the file */
keytype = keytypes[tindex];
/* calculate extra space needed for comment */
if(node->comment)
commentlen = strlen(node->comment) + 1;
if((node->typemask & LIBSSH2_KNOWNHOST_TYPE_MASK) ==
LIBSSH2_KNOWNHOST_TYPE_SHA1) {
char *namealloc;
char *saltalloc;
nlen = _libssh2_base64_encode(hosts->session, node->name,
node->name_len, &namealloc);
if(!nlen)
return _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for "
"base64-encoded host name");
nlen = _libssh2_base64_encode(hosts->session,
node->salt, node->salt_len,
&saltalloc);
if(!nlen) {
LIBSSH2_FREE(hosts->session, namealloc);
return _libssh2_error(hosts->session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for "
"base64-encoded salt");
}
nlen = strlen(saltalloc) + strlen(namealloc) + strlen(keytype) +
strlen(node->key) + commentlen + 7;
/* |1| + | + ' ' + \n + \0 = 7 */
if(nlen <= buflen)
if(node->comment)
snprintf(buf, buflen, "|1|%s|%s%s %s %s\n", saltalloc, namealloc,
keytype, node->key, node->comment);
else
snprintf(buf, buflen, "|1|%s|%s%s %s\n", saltalloc, namealloc,
keytype, node->key);
else
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_BUFFER_TOO_SMALL,
"Known-host write buffer too small");
LIBSSH2_FREE(hosts->session, namealloc);
LIBSSH2_FREE(hosts->session, saltalloc);
}
else {
nlen = strlen(node->name) + strlen(keytype) + strlen(node->key) +
commentlen + 3;
/* ' ' + '\n' + \0 = 3 */
if(nlen <= buflen)
/* these types have the plain name */
if(node->comment)
snprintf(buf, buflen, "%s%s %s %s\n", node->name, keytype, node->key,
node->comment);
else
snprintf(buf, buflen, "%s%s %s\n", node->name, keytype, node->key);
else
rc = _libssh2_error(hosts->session, LIBSSH2_ERROR_BUFFER_TOO_SMALL,
"Known-host write buffer too small");
}
/* we report the full length of the data with the trailing zero excluded */
*outlen = nlen-1;
return rc;
}
