block_template_to_proposal/
main.rs

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1//! Transforms a JSON block template into a hex-encoded block proposal.
2//!
3//! Prints the parsed template and parsed proposal structures to stderr.
4//!
5//! For usage please refer to the program help: `block-template-to-proposal --help`
6
7mod args;
8
9use std::io::Read;
10
11use color_eyre::eyre::Result;
12use serde_json::Value;
13use structopt::StructOpt;
14
15use zebra_chain::{
16    parameters::NetworkUpgrade,
17    serialization::{DateTime32, ZcashSerialize},
18};
19use zebra_rpc::methods::types::{
20    get_block_template::{proposal::proposal_block_from_template, GetBlockTemplate},
21    long_poll::LONG_POLL_ID_LENGTH,
22};
23use zebra_utils::init_tracing;
24
25/// The minimum number of characters in a valid `getblocktemplate JSON response.
26///
27/// The fields we use take up around ~800 bytes.
28const MIN_TEMPLATE_BYTES: usize = 500;
29
30/// Process entry point for `block-template-to-proposal`
31#[allow(clippy::print_stdout, clippy::print_stderr)]
32fn main() -> Result<()> {
33    // initialise
34    init_tracing();
35    color_eyre::install()?;
36
37    // get arguments from command-line or stdin
38    let args = args::Args::from_args();
39
40    let time_source = args.time_source;
41
42    // Get template from command-line or standard input
43    let template = args.template.unwrap_or_else(|| {
44        let mut template = String::new();
45        let bytes_read = std::io::stdin().read_to_string(&mut template).expect("missing JSON block template: must be supplied on command-line or standard input");
46
47        if bytes_read < MIN_TEMPLATE_BYTES {
48            panic!("JSON block template is too small: expected at least {MIN_TEMPLATE_BYTES} characters");
49        }
50
51        template
52    });
53
54    // parse string to generic json
55    let mut template: Value = serde_json::from_str(&template)?;
56    eprintln!(
57        "{}",
58        serde_json::to_string_pretty(&template).expect("re-serialization never fails")
59    );
60
61    let template_obj = template
62        .as_object_mut()
63        .expect("template must be a JSON object");
64
65    // replace zcashd keys that are incompatible with Zebra
66
67    // the longpollid key is in a node-specific format, but this tool doesn't use it,
68    // so we can replace it with a dummy value
69    template_obj["longpollid"] = "0".repeat(LONG_POLL_ID_LENGTH).into();
70
71    // provide dummy keys that Zebra requires but zcashd does not always have
72
73    // the transaction.*.required keys are not used by this tool,
74    // so we can use any value here
75    template_obj["coinbasetxn"]["required"] = true.into();
76    for tx in template_obj["transactions"]
77        .as_array_mut()
78        .expect("transactions must be a JSON array")
79    {
80        tx["required"] = false.into();
81    }
82
83    // the maxtime field is used by this tool
84    // if it is missing, substitute a valid value
85    let current_time: DateTime32 = template_obj["curtime"]
86        .to_string()
87        .parse()
88        .expect("curtime is always a valid DateTime32");
89
90    template_obj.entry("maxtime").or_insert_with(|| {
91        if time_source.uses_max_time() {
92            eprintln!("maxtime field is missing, using curtime for maxtime: {current_time:?}");
93        }
94
95        current_time.timestamp().into()
96    });
97
98    // parse the modified json to template type
99    let template: GetBlockTemplate = serde_json::from_value(template)?;
100
101    // generate proposal according to arguments
102    let proposal = proposal_block_from_template(&template, time_source, NetworkUpgrade::Nu5)?;
103    eprintln!("{proposal:#?}");
104
105    let proposal = proposal
106        .zcash_serialize_to_vec()
107        .expect("serialization to Vec never fails");
108
109    println!("{}", hex::encode(proposal));
110
111    Ok(())
112}
block_template_to_proposal/main.rs

block_template_to_proposal/
main.rs
