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114 lines
3.5 KiB
C
114 lines
3.5 KiB
C
#ifndef LIGHTNING_LIGHTNINGD_PARAM_H
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#define LIGHTNING_LIGHTNINGD_PARAM_H
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#include "config.h"
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/*
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Typesafe callback system for unmarshalling and validating json parameters.
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Typical usage:
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unsigned cltv;
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u64 *msatoshi;
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const jsmntok_t *note;
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u64 expiry;
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if (!param(cmd, buffer, params,
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p_req("cltv", json_tok_number, &cltv),
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p_opt("msatoshi", json_tok_u64, &msatoshi),
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p_opt_tok("note", ¬e),
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p_opt_def("expiry", json_tok_u64, &expiry, 3600),
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NULL))
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return;
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At this point in the code you can be assured the json tokens were successfully
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parsed. If not, param() returned false, having already called command_fail()
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with a descriptive error message. The data section of the json result contains
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the offending parameter and its value.
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cltv is a required parameter. It must be present in the json input and will
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be set appropriately.
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msatoshi is optional. If not present it will be set to NULL.
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note is also optional. It uses a special callback that simply sets note to the
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appropriate value (or NULL) and lets the handler do the validating.
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expiry is also optional and will be set to a default value if not present.
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There are canned failure messages for common callbacks. An example:
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'msatoshi' should be an unsigned 64 bit integer, not '123z'
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Otherwise a generic message is provided.
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*/
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/*
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* parse the json tokens. @params can be an array of values, or an object
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* of named values.
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*/
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bool param(struct command *cmd, const char *buffer,
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const jsmntok_t params[], ...);
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/*
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* The callback provided must follow this signature; e.g.,
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* bool json_tok_double(const char *buffer, const jsmntok_t *tok, double *arg)
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*/
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typedef bool(*param_cb)(const char *buffer, const jsmntok_t *tok, void *arg);
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/*
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* Add a handler to unmarshal a required json token into @arg. The handler must
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* return true on success and false on failure. Upon failure, command_fail will be
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* called with a descriptive error message.
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*
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* This operation is typesafe; i.e., a compilation error will occur if the types
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* of @arg and the last parameter of @cb do not match (see the weird 0*sizeof).
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*/
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#define p_req(name, cb, arg) \
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name"", \
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true, \
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(cb), \
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(arg) + 0*sizeof((cb)((const char *)NULL, \
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(const jsmntok_t *)NULL, \
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(arg)) == true), \
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(size_t)0
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/*
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* Similar to above but for optional parameters.
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* @arg must be the address of a pointer. If found during parsing, it will be
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* allocated, otherwise it will be set to NULL.
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*/
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#define p_opt(name, cb, arg) \
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name"", \
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false, \
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(cb), \
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(arg) + 0*sizeof((cb)((const char *)NULL, \
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(const jsmntok_t *)NULL, \
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*(arg)) == true), \
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sizeof(**(arg))
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/*
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* Similar to p_req but for optional parameters with defaults.
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* @arg will be set to @def if it isn't found during parsing.
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*/
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#define p_opt_def(name, cb, arg, def) \
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name"", \
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false, \
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(cb), \
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(arg) + 0*sizeof((cb)((const char *)NULL, \
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(const jsmntok_t *)NULL, \
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(arg)) == true), \
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((void)((*arg) = (def)), (size_t)0)
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/*
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* For when you want an optional raw token.
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*
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* Note: weird sizeof() does type check that arg really is a (const) jsmntok_t **.
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*/
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#define p_opt_tok(name, arg) \
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name"", \
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false, \
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json_tok_tok, \
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(arg) + 0*sizeof(*(arg) == (jsmntok_t *)NULL), \
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sizeof(const jsmntok_t *)
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#endif /* LIGHTNING_LIGHTNINGD_PARAM_H */
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