Callbacks

From Libssh2

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Allocators

#define LIBSSH2_ALLOC_FUNC(name)     void *name(size_t count, void **abstract)
#define LIBSSH2_REALLOC_FUNC(name)   void *name(void *ptr, size_t count, void **abstract)
#define LIBSSH2_FREE_FUNC(name)      void name(void *ptr, void **abstract)

Allocator callbacks are called by the library anytime memory needs to be allocated, reallocated, or freed. If no alternate allocator functions are declared when calling libssh2_session_init_ex(), the system allocation functions: malloc(), realloc(), and free() are used instead.

  • name
    Name to be assigned to allocator function. This is also the name which will be passed to libssh2_session_init_ex().
  • count
    Number of bytes to allocate or reallocate.
  • ptr
    Existing pointer to free or reallocate.
  • abstract
    Doubly derefferenced pointer to abstract data stored in the session object. The singly deferenced void* which this pointer refers to may be modified in place by the callback if necessary.
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Transport

#define LIBSSH2_IGNORE_FUNC(name)       void name(LIBSSH2_SESSION *session, const char *message, int message_len, void **abstract)
#define LIBSSH2_DEBUG_FUNC(name)        void name(LIBSSH2_SESSION *session, int always_display, const char *message, int message_len, const char *language, int language_len, void **abstract)
#define LIBSSH2_DISCONNECT_FUNC(name)   void name(LIBSSH2_SESSION *session, int reason, const char *message, int message_len, const char *language, int language_len, void **abstract)
#define LIBSSH2_MACERROR_FUNC(name)     int  name(LIBSSH2_SESSION *session, const char *packet, int packet_len, void **abstract)
#define LIBSSH2_X11_OPEN_FUNC(name)     void name(LIBSSH2_SESSION *session, LIBSSH2_CHANNEL *channel, char *shost, int sport, void **abstract)

Transport callbacks are triggered in response to special events at the transport layer such as the receipt of a special packet or a security exception. These callbacks are set following session initialization using libssh2_session_callback_set().

  • name
    Name to be assigned to allocator function. This is also the name which will be passed to libssh2_session_callback_set().
  • session
    Reference to the session object which received the special event.
  • always_display
    Boolean flag. When set, recipient is strongly advised to display the message to any interactive user.
  • reason
    Numeric reason code for disconnection, one of the Disconnect Reason constants.
  • message
    Human readable message relevant to the callback.
  • message_len
    Length of message in bytes.
  • language
    Language/encoding specifier
  • language_len
    Length of language parameter.
  • packet
    Raw packet encountered during MAC verification failure
  • packet_len
    Length of packet
  • channel
    Channel object associated with the X11 request. X11 requests are considered by this library as a transport layer event as they occur out-of-band from channel data.
  • shost
    Source host which generated the X11 request.
  • sport
    Source port X11 request originated from.
  • abstract
    Doubly derefferenced pointer to abstract data stored in the session object. The singly deferenced void* which this pointer refers to may be modified in place by the callback if necessary.
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Authentication

#define LIBSSH2_PASSWD_CHANGEREQ_FUNC(name)   void name(LIBSSH2_SESSION *session, char **newpw, int *newpw_len, void **abstract)
  • name
    Name to be assigned to allocator function. This is also the name which will be passed to libssh2_userauth_password_ex().
  • session
    Reference to the session object which received the password change request.
  • newpw
    Callback populates this variable reference with the new password for the account being changed.
  • newpw_len
    Callback populates this variable reference with the length of newpw
  • abstract
    Doubly derefferenced pointer to abstract data stored in the session object. The singly deferenced void* which this pointer refers to may be modified in place by the callback if necessary. 
#define LIBSSH2_USERAUTH_KBDINT_RESPONSE_FUNC(name_)   void name_(const char *name, int name_len, const char *instruction, int instruction_len, int num_prompts, const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts, LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses, void **abstract)
  • name_
    Name to be assigned to allocator function. This is also the name which will be passed to libssh2_userauth_keyboard_interactive_ex().
  • name
    Name given by host to the current authentication challenge.
  • name_len
    Length of name
  • instruction
    Human readable instructions for associated prompts.
  • instruction_len
    Length of instruction parameter.
  • num_prompts
    Number of elements in prompts vector.
  • prompts
    Vector of num_prompts instances of LIBSSH2_USERAUTH_KBDINT_PROMPT structures.
  • responses
    Preallocated vector of num_prompts instances of LIBSSH2_USERAUTH_KBDINT_RESPONSE structures. Callback populates this vector with appropriate responses to the prompts in the corresponding indices of the prompts vector.
  • abstract
    Doubly derefferenced pointer to abstract data stored in the session object. The singly deferenced void* which this pointer refers to may be modified in place by the callback if necessary.
Retrieved from "http://www.libssh2.org/wiki/index.php/Callbacks"