## CVM

# CVM Version 2 Client Library

The CVM version 2 client library defines the following functions:

`int cvm_client_authenticate(const char* module, unsigned count, struct cvm_credential* credentials)`

  This is the main entry point to the library. Set up the credentials as an array and call `cvm_client_authenticate`. The credentials must contain a `CVM_CRED_ACCOUNT` entry. The function will return 0 if authentication succeeded and an error code otherwise. The credentials have the following structure:

      struct
      cvm_credential { unsigned type; str value; }

  If `$CVM_LOOKUP_SECRET` is set, and no `CVM_CRED_SECRET` credential is present in the `credentials`, its value is added to the set of outgoing credentials automatically to assist with the workings of lookup modules.

  If authentication succeeds, this routine automatically retrieves `cvm_fact_username`, `cvm_fact_userid`, `cvm_fact_groupid`, `cvm_fact_directory`, and `cvm_fact_shell`. `cvm_fact_realname`, `cvm_fact_groupname`, `cvm_fact_sys_username`, `cvm_fact_sys_directory`, and `cvm_fact_domain` are also set if they were present in the results.

  The client should change directory to the named home directory and drop root priviledges as soon as possible after successful authentication. Where reasonable, the client should also chroot to the directory for added protection.

  A random tag is added to the transmitted data to prevent spoofing when a remote module is being contacted (UDP mode). Its size is set by `$CVM_RANDOM_BYTES`, and defaults to 8 bytes.

`int cvm_client_split_account(str* account, str* domain)`

  This function splits a domain name, if present, from of the account name. It searches for the last instance of any character from `cvm_client_account_split_chars` in `account`. If found, `domain` is replaced with the portion of `account` following that character, and `account` is truncated before that character. `cvm_client_account_split_chars` defaults to "`@`", which may be overridden by either setting it to a different string from the client program or by setting the `$CVM_ACCOUNT_SPLIT_CHARS` environment variable. Setting it to an empty string will effectively prevent parsing of the account name.

`int cvm_client_authenticate_password(const char* module, const char* account, const char* domain, const char* password, int split_account)`

  This is a convenience wrapper function for the `cvm_authenticate` and `cvm_split_account` functions. The `domain` and `password` credentials are only sent if they are not `NULL` and not empty.

`int cvm_client_fact_str(unsigned number, const char** data)`

  Retrieves a fact from the data returned by the module as a NUL-terminated string. Returns zero if the fact was present, and `CVME_NOFACT` otherwise. Successive calls to this function with the same `number` return subsequent facts if more than one instance of the fact was present.

`int cvm_client_fact_uint(unsigned number, unsigned long* data)`

  Retrieves a fact from the data returned by the module as an unsigned integer. Returns zero if the fact was present and was an unsigned integer. Returns `CVME_BAD_MODDATA` if the fact was present but was not an unsigned integer. Successive calls to this function with the same `number` return subsequent facts if more than one instance of the fact was present.

`const char* cvm_client_ucspi_domain(void)`

  Retrieves the UCSPI local domain from the environment variable named `${PROTO}LOCALHOST`. Use this as the `domain` paramenter to `cvm_authenticate` in all UCSPI servers that have no other means of determining the domain name.

`int cvm_client_setenv(void)`

  Exports the following environment variables based on their associated CVM fact. If the fact was optional and was not present in the results from the module, the environment variable will not be set or unset.

  Variable | CVM Fact
  --- | ---
  `USER` | `CVM_FACT_USERNAME`
  `UID` | `CVM_FACT_USERID`
  `GID` | `CVM_FACT_GROUPID`
  `NAME` | `CVM_FACT_REALNAME`
  `HOME` | `CVM_FACT_DIRECTORY`
  `SHELL` | `CVM_FACT_SHELL`
  `GROUP` | `CVM_FACT_GROUPNAME`
  `DOMAIN` | `CVM_FACT_DOMAIN`
  `MAIL` | `CVM_FACT_MAILBOX`
  `MAILBOX` | `CVM_FACT_MAILBOX`
  `MAILDIR` | `CVM_FACT_MAILBOX`

`int cvm_client_setugid(void)`

  Calls `chdir`, `setgid` and `setuid` with appropriate values based on the data returned from the authentication. Returns zero if any of the calls failed.