ndhc/nk/exec.h

// Copyright 2003-2022 Nicholas J. Kain <njkain at gmail dot com>
// SPDX-License-Identifier: MIT
#ifndef NCM_EXEC_H_
#define NCM_EXEC_H_

struct nk_exec_env
{
    char *env[32];
    char envbuf[4096];
};

int nk_generate_env(struct nk_exec_env *xe, uid_t uid, const char *chroot_path, const char *path_var);
void nk_generate_env_print_error(int err);
void __attribute__((noreturn))
    nk_execute(const char *command, const char *args, char * const envp[]) ;

#endif
Update to latest nk/exec.c; see ncron repo for changes. Notably, nk_generate_env() no longer calls malloc(). 2022-02-25 06:43:42 -05:00			`// Copyright 2003-2022 Nicholas J. Kain <njkain at gmail dot com>`
Support running an executable file when a new lease is acquired. If no 'script-file = SCRIPTFILE' is specified in the configuration file and if no '-X SCRIPTFILE' or '--script-file SCRIPTFILE' command argument is provided, then this functionality is entirely inactive and no associated subprocess is spawned. Otherwise, ndhc will spawn a subprocess that runs as root that has the sole job of forking off a subprocess that exec's the specified script in a sanitized and fixed-state environment whenever a new DHCPv4 lease is acquired. Note that this script is provided no information about ndhc or the DHCP state in the environment or in any argument fields; it is the responsibility of this script to gather whatever information it needs from either the filesystem or syscalls. This design is intended to avoid the historical problems that are associated with dhcp clients invoking scripts. The path of the scriptfile cannot be changed after ndhc is initially run; ndhc forks off the privsep script subprocess that executes scripts after it has read the configuration file and command arguments, but before it begins processing network data; thus, it is impossible for the network-handling process to modify or influence the script assuming proper OS memory protection. The privsep channel communicates that the script should be run by simply writing a newline; anything else will result in ndhc terminating itself. Before the recommended way to update system state after a change in lease information was to run the fcactus program and watch the associated leasefile for the interface for modification; now no external program is needed for this job. 2022-02-24 00:52:26 -05:00			`// SPDX-License-Identifier: MIT`
			`#ifndef NCM_EXEC_H_`
			`#define NCM_EXEC_H_`

Update to latest nk/exec.c; see ncron repo for changes. Notably, nk_generate_env() no longer calls malloc(). 2022-02-25 06:43:42 -05:00			`struct nk_exec_env`
			`{`
			`char *env[32];`
			`char envbuf[4096];`
			`};`

			`int nk_generate_env(struct nk_exec_env xe, uid_t uid, const char chroot_path, const char *path_var);`
			`void nk_generate_env_print_error(int err);`
Support running an executable file when a new lease is acquired. If no 'script-file = SCRIPTFILE' is specified in the configuration file and if no '-X SCRIPTFILE' or '--script-file SCRIPTFILE' command argument is provided, then this functionality is entirely inactive and no associated subprocess is spawned. Otherwise, ndhc will spawn a subprocess that runs as root that has the sole job of forking off a subprocess that exec's the specified script in a sanitized and fixed-state environment whenever a new DHCPv4 lease is acquired. Note that this script is provided no information about ndhc or the DHCP state in the environment or in any argument fields; it is the responsibility of this script to gather whatever information it needs from either the filesystem or syscalls. This design is intended to avoid the historical problems that are associated with dhcp clients invoking scripts. The path of the scriptfile cannot be changed after ndhc is initially run; ndhc forks off the privsep script subprocess that executes scripts after it has read the configuration file and command arguments, but before it begins processing network data; thus, it is impossible for the network-handling process to modify or influence the script assuming proper OS memory protection. The privsep channel communicates that the script should be run by simply writing a newline; anything else will result in ndhc terminating itself. Before the recommended way to update system state after a change in lease information was to run the fcactus program and watch the associated leasefile for the interface for modification; now no external program is needed for this job. 2022-02-24 00:52:26 -05:00			`void __attribute__((noreturn))`
			`nk_execute(const char command, const char args, char * const envp[]) ;`

			`#endif`