SysTutorials Posts

NAME ares_library_cleanup – c-ares library deinitialization SYNOPSIS #include <ares.h> void ares_library_cleanup(void) cc file.c – lcares DESCRIPTION The ares_library_cleanup function uninitializes the c-ares library, freeing all resources previously acquired by ares_library_init(3) when the library was initialized, provided there was only one single previous call to ares_library_init(3). If there was more than one previous call to ares_library_init(3),…

NAME ares_init, ares_init_options – Initialize a resolver channel SYNOPSIS #include <ares.h> int ares_init(ares_channel *channelptr) int ares_init_options(ares_channel *channelptr, struct ares_options *options, int optmask) cc file.c – lcares DESCRIPTION The ares_init function initializes a communications channel for name service lookups. If it returns successfully, ares_init will set the variable pointed to by channelptr to a handle used…

NAME ares_init, ares_init_options – Initialize a resolver channel SYNOPSIS #include <ares.h> int ares_init(ares_channel *channelptr) int ares_init_options(ares_channel *channelptr, struct ares_options *options, int optmask) cc file.c – lcares DESCRIPTION The ares_init function initializes a communications channel for name service lookups. If it returns successfully, ares_init will set the variable pointed to by channelptr to a handle used…

NAME ares_inet_pton – convert an IPv4 or IPv6 address from text to binary form SYNOPSIS #include <ares.h> const char *ares_inet_pton(int af, const char *src, void *dst); DESCRIPTION This is a portable version with the identical functionality of the commonly available inet_pton. The ares_inet_pton() function converts the address in its standard text presentation form into its…

NAME ares_inet_ntop – convert a network format address to presentation format SYNOPSIS #include <ares.h> const char * ares_inet_ntop(int af, const void *src, char *dst, ares_socklen_t size); DESCRIPTION This is a portable version with the identical functionality of the commonly available inet_ntop. The ares_inet_ntop() function converts a numeric address into a text string suitable for presentation….

NAME ares_getsock – get socket descriptors to wait on SYNOPSIS #include <ares.h> int ares_getsock(ares_channel channel, ares_socket_t *socks, int numsocks); DESCRIPTION The ares_getsock function retrieves the set of socket descriptors which the calling application should wait on for reading and/or writing for the processing of name service queries pending on the name service channel identified by…

NAME ares_getnameinfo – Address-to-nodename translation in protocol-independent manner SYNOPSIS #include <ares.h> typedef void (*ares_nameinfo_callback)(void *arg, int status, void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, ares_socklen_t salen, int flags, ares_nameinfo_callback callback, void *arg) DESCRIPTION The ares_getnameinfo function is defined for protocol-independent address translation. The function is a combination of ares_gethostbyaddr(3) and getservbyport(3). The function will translate…

NAME ares_gethostbyname_file – Lookup a name in the system’s hosts file SYNOPSIS #include <ares.h> int ares_gethostbyname_file(ares_channel channel, const char *name, int family, struct hostent **host) DESCRIPTION The ares_gethostbyname_file function performs a host lookup by name against the system’s hosts file (or equivalent local hostname database). The channel parameter is required, but no asynchronous queries are…

NAME ares_gethostbyname – Initiate a host query by name SYNOPSIS #include <ares.h> typedef void (*ares_host_callback)(void *arg, int status, void ares_gethostbyname(ares_channel channel, const char *name, int family, ares_host_callback callback, void *arg) DESCRIPTION The ares_gethostbyname function initiates a host query by name on the name service channel identified by channel. The parameter name gives the hostname as…

NAME ares_gethostbyaddr – Initiate a host query by address SYNOPSIS #include <ares.h> typedef void (*ares_host_callback)(void *arg, int status, void ares_gethostbyaddr(ares_channel channel, const void *addr, int addrlen, int family, ares_host_callback callback, void *arg) DESCRIPTION The ares_gethostbyaddr function initiates a host query by address on the name service channel identified by channel. The parameters addr and addrlen…

NAME ares_get_servers – Retrieve name servers from an initialized ares_channel SYNOPSIS #include <ares.h> int ares_get_servers(ares_channel channel, struct ares_addr_node **servers) DESCRIPTION The ares_get_servers(3) function retrieves name servers configuration from the channel data identified by channel, as a linked list of ares_addr_node structs storing a pointer to the first node at the address specified by servers. Function…

NAME ares_free_string – Free strings allocated by ares functions SYNOPSIS #include <ares.h> void ares_free_string(void *str) DESCRIPTION The ares_free_string function frees a string allocated by an ares function. SEE ALSO ares_mkquery(3) ares_expand_string(3) AUTHOR Greg Hudson, MIT Information Systems Copyright 2000 by the Massachusetts Institute of Technology. Index

NAME ares_free_hostent – Free host structure allocated by ares functions SYNOPSIS #include <ares.h> void ares_free_hostent(struct hostent *host) DESCRIPTION The ares_free_hostent function frees a struct hostent allocated by one of the functions ares_parse_a_reply(3), ares_parse_aaaa_reply(3), or ares_parse_ptr_reply(3). NOTES It is not necessary (and is not correct) to free the host structure passed to the callback functions for…

NAME ares_free_data – Free data allocated by several c-ares functions SYNOPSIS #include <ares.h> void ares_free_data(void *dataptr) cc file.c – lcares DESCRIPTION The ares_free_data(3) function frees one or more data structures allocated and returned by several c-ares functions. Specifically the data returned by the following list of functions must be deallocated using this function. ares_get_servers(3) When…

NAME ares_fds – Get file descriptors to select on for name service SYNOPSIS #include <ares.h> int ares_fds(ares_channel channel, fd_set *read_fds, DESCRIPTION The ares_fds function retrieves the set of file descriptors which the calling application should select on for reading and writing for the processing of name service queries pending on the name service channel identified…

NAME ares_expand_string – Expand a length encoded string SYNOPSIS #include <ares.h> int ares_expand_string(const unsigned char *encoded, const unsigned char *abuf, int alen, unsigned char **s, long *enclen) DESCRIPTION The ares_expand_string function converts a length encoded string to a NUL-terminated C string. The argument encoded gives the beginning of the encoded string, and the arguments abuf…

NAME ares_expand_name – Expand a DNS-encoded domain name SYNOPSIS #include <ares.h> int ares_expand_name(const unsigned char *encoded, const unsigned char *abuf, int alen, char **s, long *enclen) DESCRIPTION The ares_expand_name function converts a DNS-encoded domain name to a dot-separated C string. The argument encoded gives the beginning of the encoded domain name, and the arguments abuf…

NAME ares_dup – Duplicate a resolver channel SYNOPSIS #include <ares.h> int ares_dup(ares_channel *dest, ares_channel source) DESCRIPTION The ares_dup(3) function duplicates an existing communications channel for name service lookups. If it returns successfully, ares_dup(3) will set the variable pointed to by dest to a handle used to identify the name service channel. The caller should invoke…

NAME ares_destroy_options – Destroy options initialized with ares_save_options SYNOPSIS #include <ares.h> void ares_destroy_options(struct ares_options *options) DESCRIPTION The ares_destroy_options function destroys the options struct identified by options, freeing all memory allocated by ares_save_options. SEE ALSO ares_save_options(3), ares_init_options(3) AUTHOR Brad House Copyright 1998 by the Massachusetts Institute of Technology. Index

NAME ares_destroy – Destroy a resolver channel SYNOPSIS #include <ares.h> void ares_destroy(ares_channel channel) DESCRIPTION The ares_destroy function destroys the name service channel identified by channel, freeing all memory and closing all sockets used by the channel. ares_destroy invokes the callbacks for each pending query on the channel, passing a status of ARES_EDESTRUCTION. These calls give…