From 08f4a544063d5c2ff90105e54bc0510bbaf4a7a1 Mon Sep 17 00:00:00 2001 From: unknown Date: Mon, 19 Sep 2011 17:37:04 +0200 Subject: [PATCH] Added libssh2_session_supported_algs() --- docs/libssh2_session_supported_algs.3 | 29 +++++++++++++ include/libssh2.h | 7 +++ src/comp.c | 10 ++++ src/kex.c | 75 +++++++++++++++++++++++++++++++++ 4 files changed, 121 insertions(+), 0 deletions(-) create mode 100644 docs/libssh2_session_supported_algs.3 diff --git a/docs/libssh2_session_supported_algs.3 b/docs/libssh2_session_supported_algs.3 new file mode 100644 index 0000000..8b8ffd0 --- /dev/null +++ b/docs/libssh2_session_supported_algs.3 @@ -0,0 +1,29 @@ +.TH libssh2_session_supported_algs 3 "19 Sep 2011" "libssh2 1.4.0" "libssh2 manual" +.SH NAME +libssh2_session_supported_algs - get a list of supported algorithms for the given method_type +.SH SYNOPSIS +#include + +int libssh2_session_supported_algs(int method_type, char** algs, unsigned int nalgs); +.SH DESCRIPTION +Get a list of supported algorithms for each method_type. The method_type parameter is equivalent +to method_type in \fIlibssh2_session_method_pref(3)\fP. Algs must be user preallocated array of pointers to strings +(e.g. char* methods[N_METHODS]) and nalgs is a number of preallocated elemnts in this array. +If successful, the function will fill this array with supported algorithms (the same names as defined in RFC 4253) +and terminate it with a NULL pointer. +.SH RETURN VALUE +On success, a number of returned algorithms (i.e a positive number will be returned). +In case of a failure, an error code (a negative number, see below) is returned. +.SH ERRORS +\fILIBSSH2_ERROR_BAD_USE\fP - Invalid value of nalgs. + +\fILIBSSH2_ERROR_METHOD_NOT_SUPPORTED\fP - Unknown method type. + +\fILIBSSH2_ERROR_INVAL\fP - Internal error (normally should not occur). + +\fILIBSSH2_ERROR_BUFFER_TOO_SMALL\fP - Preallocated buffer algs is too short. +.SH AVAILABILITY +Added in 1.4.0 +.SH SEE ALSO +.BR libssh2_session_methods(3), +.BR libssh2_session_method_pref()(3), diff --git a/include/libssh2.h b/include/libssh2.h index 8dc547c..0b84083 100644 --- a/include/libssh2.h +++ b/include/libssh2.h @@ -489,6 +489,13 @@ LIBSSH2_API int libssh2_session_flag(LIBSSH2_SESSION *session, int flag, int value); LIBSSH2_API const char *libssh2_session_banner_get(LIBSSH2_SESSION *session); +/* + Retrieve a list of supported algorithms for given method_type (see ibssh2_session_method_pref) + algs - user preallocated array of pointers to string which will be filled (and NULL terminated) in by the function + nalgs - number of reserved elements in algs, incl. the NULL termination +*/ +LIBSSH2_API int libssh2_session_supported_algs(int method_type, char** algs, unsigned int nalgs); + /* Userauth API */ LIBSSH2_API char *libssh2_userauth_list(LIBSSH2_SESSION *session, const char *username, diff --git a/src/comp.c b/src/comp.c index 0296f62..47c056f 100644 --- a/src/comp.c +++ b/src/comp.c @@ -383,6 +383,16 @@ static const LIBSSH2_COMP_METHOD *no_comp_methods[] = { const LIBSSH2_COMP_METHOD ** _libssh2_comp_methods(LIBSSH2_SESSION *session) { + /* + Looks like the original implementation expects a non-NULL session only. + When asking for supported algorithms, however, session will typically be NULL, + so the following is necessary to avoid NULL dereferrencing caused core dumps. + */ + if ( NULL==session ) + { + return comp_methods; + } + if(session->flag.compress) return comp_methods; else diff --git a/src/kex.c b/src/kex.c index d26b5f3..9614bf9 100644 --- a/src/kex.c +++ b/src/kex.c @@ -1896,3 +1896,78 @@ libssh2_session_method_pref(LIBSSH2_SESSION * session, int method_type, return 0; } +/* + * libssh2_session_supported_algs() + * returns a number of returned algorithms (a positive number) on success, + * a negative number on failure + */ + +LIBSSH2_API int libssh2_session_supported_algs(int method_type, char** algs, unsigned int nalgs) +{ + /* + TODO: do more appropriate error codes exist? + */ + unsigned int i; + unsigned int ialg; + const LIBSSH2_COMMON_METHOD **mlist; + + if ( nalgs<=0 ) + { + return LIBSSH2_ERROR_BAD_USE; /* invalid nalgs */ + } + + switch (method_type) + { + case LIBSSH2_METHOD_KEX: + mlist = (const LIBSSH2_COMMON_METHOD **) libssh2_kex_methods; + break; + + case LIBSSH2_METHOD_HOSTKEY: + mlist = (const LIBSSH2_COMMON_METHOD **) libssh2_hostkey_methods(); + break; + + case LIBSSH2_METHOD_CRYPT_CS: + case LIBSSH2_METHOD_CRYPT_SC: + mlist = (const LIBSSH2_COMMON_METHOD **) libssh2_crypt_methods(); + break; + + case LIBSSH2_METHOD_MAC_CS: + case LIBSSH2_METHOD_MAC_SC: + mlist = (const LIBSSH2_COMMON_METHOD **) _libssh2_mac_methods(); + break; + + case LIBSSH2_METHOD_COMP_CS: + case LIBSSH2_METHOD_COMP_SC: + mlist = (const LIBSSH2_COMMON_METHOD **) _libssh2_comp_methods(NULL); + break; + + default: + return LIBSSH2_ERROR_METHOD_NOT_SUPPORTED; /* unknown method type */ + } /* switch */ + + if ( NULL==mlist ) + { + return LIBSSH2_ERROR_INVAL; /* weird situation */ + } + + + for ( i=0, ialg=0; ialgname ) + { + /* probably this shouldn't occur but handle it gently anyway */ + continue; + } + + algs[ialg++] = mlist[i]->name; + } /* for i, ialg */ + + /* as mentioned, the returned list is NULL terminated */ + algs[ialg] = NULL; + if ( ialg == nalgs-1 ) + { + return LIBSSH2_ERROR_BUFFER_TOO_SMALL; /* buffer too short */ + } + + return ialg; +} -- 1.7.6.msysgit.0