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//! High-level paste operations.
//!
//! Each function combines local storage and DHT interaction
//! into a single call: put, get, delete, pin/unpin.
use std::time::Duration;
use tesseras_dht::Node;
use crate::base58;
use crate::crypto;
use crate::paste::{MAX_PASTE_SIZE, Paste};
use crate::store::PasteStore;
/// Timeout for blocking DHT lookups.
const OP_TIMEOUT: Duration = Duration::from_secs(30);
/// Errors from paste operations.
#[derive(Debug)]
pub enum PasteError {
InvalidKey,
NotFound,
Expired,
DecryptionFailed,
TooLarge,
Internal(String),
}
impl std::fmt::Display for PasteError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::InvalidKey => write!(f, "invalid key"),
Self::NotFound => write!(f, "not found"),
Self::Expired => write!(f, "expired"),
Self::DecryptionFailed => write!(f, "decryption failed"),
Self::TooLarge => write!(f, "paste too large"),
Self::Internal(msg) => write!(f, "internal: {msg}"),
}
}
}
/// Decode the hash portion of a key string ("hash#enckey" or "hash").
/// Returns the 32-byte hash.
fn parse_hash(key_str: &str) -> Result<Vec<u8>, PasteError> {
let hash_b58 = key_str.split_once('#').map(|(h, _)| h).unwrap_or(key_str);
let hash = base58::decode(hash_b58).ok_or(PasteError::InvalidKey)?;
if hash.len() != 32 {
return Err(PasteError::InvalidKey);
}
Ok(hash)
}
/// Store a paste. If `encrypt` is true, encrypts the content and
/// returns "hash#enckey" in base58. Otherwise returns just the hash.
pub fn put_paste(
node: &mut Node,
store: &PasteStore,
content: &[u8],
ttl_secs: u64,
encrypt: bool,
) -> Result<String, PasteError> {
if content.len() > MAX_PASTE_SIZE {
return Err(PasteError::TooLarge);
}
let (paste_content, enc_key) = if encrypt {
let key = crypto::generate_key();
(crypto::encrypt(&key, content), Some(key))
} else {
(content.to_vec(), None)
};
let paste = Paste::new(paste_content, ttl_secs);
let serialized = paste.to_bytes();
let hash = Paste::content_key(&paste.content);
store
.put_paste(&hash, &serialized)
.map_err(|e| PasteError::Internal(e.to_string()))?;
let dht_ttl = std::cmp::min(ttl_secs, u16::MAX as u64) as u16;
node.put(&hash, &serialized, dht_ttl, false);
let hash_b58 = base58::encode(&hash);
let label = if encrypt { "encrypted" } else { "public" };
log::info!(
"put: stored {label} paste {hash_b58} ({} bytes)",
content.len()
);
match enc_key {
Some(key) => Ok(format!("{hash_b58}#{}", base58::encode(&key))),
None => Ok(hash_b58),
}
}
/// Retrieve a paste by key ("hash#enckey" or bare "hash").
/// Tries local store first, then falls back to a blocking DHT lookup.
pub fn get_paste(
node: &mut Node,
store: &PasteStore,
key_str: &str,
) -> Result<Vec<u8>, PasteError> {
let (hash_b58, enc_key_b58) = match key_str.split_once('#') {
Some((h, k)) => (h, Some(k)),
None => (key_str, None),
};
let hash = base58::decode(hash_b58).ok_or(PasteError::InvalidKey)?;
if hash.len() != 32 {
return Err(PasteError::InvalidKey);
}
let data = if let Some(local) = store.get_paste(&hash) {
local
} else {
let vals = node.get_blocking(&hash, OP_TIMEOUT);
if vals.is_empty() {
return Err(PasteError::NotFound);
}
// Verify DHT result: the content hash must match the
// requested key to prevent a malicious node from
// injecting arbitrary data.
match vals.iter().find(|v| {
Paste::from_bytes(v)
.map(|p| Paste::content_key(&p.content) == *hash)
.unwrap_or(false)
}) {
Some(v) => v.clone(),
None => return Err(PasteError::NotFound),
}
};
let paste = Paste::from_bytes(&data).ok_or(PasteError::InvalidKey)?;
if paste.is_expired() && !store.is_pinned(&hash) {
return Err(PasteError::Expired);
}
if let Some(kb58) = enc_key_b58 {
let key_bytes = base58::decode(kb58).ok_or(PasteError::InvalidKey)?;
if key_bytes.len() != crypto::KEY_SIZE {
return Err(PasteError::InvalidKey);
}
let mut key = [0u8; crypto::KEY_SIZE];
key.copy_from_slice(&key_bytes);
crypto::decrypt(&key, &paste.content)
.ok_or(PasteError::DecryptionFailed)
} else {
Ok(paste.content)
}
}
/// Delete a paste from local store and the DHT.
pub fn delete_paste(
node: &mut Node,
store: &PasteStore,
key_str: &str,
) -> Result<(), PasteError> {
let hash = parse_hash(key_str)?;
store.remove_paste(&hash);
node.delete(&hash);
let hash_b58 = key_str.split_once('#').map(|(h, _)| h).unwrap_or(key_str);
log::info!("del: removed paste {hash_b58}");
Ok(())
}
/// Parse a key and resolve the 32-byte hash (stripping any #enckey).
pub fn resolve_hash(key: &str) -> Result<Vec<u8>, PasteError> {
parse_hash(key)
}
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