Struct sequoia_openpgp::cert::prelude::CertParser

source · 
pub struct CertParser<'a> { /* private fields */ }
Expand description

An iterator over a sequence of certificates, i.e., an OpenPGP keyring.

The source of packets is a fallible iterator over Packets. In this way, it is possible to propagate parse errors.

A CertParser returns each TPK or TSK that it encounters. Note: if you don’t actually need all of the certificates, it is usually faster to use a RawCertParser and only fully parse and canonicalize those certificates that are relevant.

A CertParser’s behavior can be modeled using a simple state machine.

In the first and initial state, it looks for the start of a certificate, a Public Key packet or a Secret Key packet. When it encounters such a packet it buffers it, and transitions to the second state. Any other packet or an error causes it to emit an error and stay in the same state. When the source of packets is exhausted, it enters the End state.

In the second state, it looks for packets that belong to a certificate’s body. If it encounters a valid body packet, then it buffers it and stays in the same state. If it encounters the start of a certificate, then it emits the buffered certificate, buffers the packet, and stays in the same state. If it encounters an invalid packet (e.g., a Literal Data packet), it emits two items, the buffered certificate, and an error, and then it transitions back to the initial state. When the source of packets is exhausted, it emits the buffered certificate and enters the end state.

In the end state, it emits None.

                      Invalid Packet / Error
                    ,------------------------.
                    v                        |
   Not a      +---------+                +---------+
   Start  .-> | Looking | -------------> | Looking | <-. Cert
 of Cert  |   |   for   |     Start      |   for   |   | Body
  Packet  |   |  Start  |    of Cert     |  Cert   |   | Packet
 / Error  `-- | of Cert |     Packet     |  Body   | --'
              +---------+            .-> +---------+
                   |                 |      |  |
                   |                 `------'  |
                   |    Start of Cert Packet   |
                   |                           |
               EOF |         +-----+           | EOF
                    `------> | End | <---------'
                             +-----+
                              |  ^
                              `--'

The parser does not recurse into containers, thus when it encounters a container like a Compressed Data Packet, it will return an error even if the container contains a valid certificate.

The parser considers unknown packets to be valid body packets. (In a Cert, these show up as Unknown components.) The goal is to provide some future compatibility.

Examples

Print information about all certificates in a keyring:

use sequoia_openpgp as openpgp;
use openpgp::parse::Parse;
use openpgp::parse::PacketParser;
use openpgp::cert::prelude::*;

let ppr = PacketParser::from_bytes(&keyring)?;
for certo in CertParser::from(ppr) {
    match certo {
        Ok(cert) => {
            println!("Key: {}", cert.fingerprint());
            for ua in cert.userids() {
                println!("  User ID: {}", ua.userid());
            }
        }
        Err(err) => {
            eprintln!("Error reading keyring: {}", err);
        }
    }
}

When an invalid packet is encountered, an error is returned and parsing continues:

use sequoia_openpgp as openpgp;
use openpgp::cert::prelude::*;
use openpgp::packet::prelude::*;
use openpgp::types::DataFormat;

let mut lit = Literal::new(DataFormat::Text);
lit.set_body(b"test".to_vec());

let (alice, _) =
      CertBuilder::general_purpose(None, Some("alice@example.org"))
      .generate()?;
let (bob, _) =
      CertBuilder::general_purpose(None, Some("bob@example.org"))
      .generate()?;

let mut packets : Vec<Packet> = Vec::new();
packets.extend(alice.clone());
packets.push(lit.clone().into());
packets.push(lit.clone().into());
packets.extend(bob.clone());

let r : Vec<Result<Cert>> = CertParser::from(packets).collect();
assert_eq!(r.len(), 4);
assert_eq!(r[0].as_ref().unwrap().fingerprint(), alice.fingerprint());
assert!(r[1].is_err());
assert!(r[2].is_err());
assert_eq!(r[3].as_ref().unwrap().fingerprint(), bob.fingerprint());

Implementations§

Creates a CertParser from a Result<Packet> iterator.

Note: because we implement From<Packet> for Result<Packet>, it is possible to pass in an iterator over Packets.

Examples

From a Vec<Packet>:

use sequoia_openpgp as openpgp;
use openpgp::cert::prelude::*;
use openpgp::packet::prelude::*;

for certo in CertParser::from_iter(packets) {
    match certo {
        Ok(cert) => {
            println!("Key: {}", cert.fingerprint());
            for ua in cert.userids() {
                println!("  User ID: {}", ua.userid());
            }
        }
        Err(err) => {
            eprintln!("Error reading keyring: {}", err);
        }
    }
}

Filters the Certs prior to validation.

By default, the CertParser only returns valdiated Certs. Checking that a certificate’s self-signatures are valid, however, is computationally expensive, and not always necessary. For example, when looking for a small number of certificates in a large keyring, most certificates can be immediately discarded. That is, it is more efficient to filter, validate, and double check, than to validate and filter. (It is necessary to double check, because the check might have been on an invalid part. For example, if searching for a key with a particular Key ID, a matching key might not have any self signatures.)

If the CertParser gave out unvalidated Certs, and provided an interface to validate them, then the caller could implement this check-validate-double-check pattern. Giving out unvalidated Certs, however, is dangerous: inevitably, a Cert will be used without having been validated in a context where it should have been.

This function avoids this class of bugs while still providing a mechanism to filter Certs prior to validation: the caller provides a callback that is invoked on the unvalidated Cert. If the callback returns true, then the parser validates the Cert, and invokes the callback a second time to make sure the Cert is really wanted. If the callback returns false, then the Cert is skipped.

Note: calling this function multiple times on a single CertParser will not replace the existing filter, but install multiple filters.

Examples
use sequoia_openpgp as openpgp;
use openpgp::cert::prelude::*;

for certr in CertParser::from(ppr)
    .unvalidated_cert_filter(|cert, _| {
        for component in cert.keys() {
            if component.key().keyid() == some_keyid {
                return true;
            }
        }
        false
    })
{
    match certr {
        Ok(cert) => {
            // The Cert contains the subkey.
        }
        Err(err) => {
            eprintln!("Error reading keyring: {}", err);
        }
    }
}

Trait Implementations§

Returns the “default value” for a type. Read more

Initializes a CertParser from a PacketParser.

Converts to this type from the input type.
Converts to this type from the input type.
The type of the elements being iterated over.
Advances the iterator and returns the next value. Read more
🔬This is a nightly-only experimental API. (iter_next_chunk)
Advances the iterator and returns an array containing the next N values. Read more
Returns the bounds on the remaining length of the iterator. Read more
Consumes the iterator, counting the number of iterations and returning it. Read more
Consumes the iterator, returning the last element. Read more
🔬This is a nightly-only experimental API. (iter_advance_by)
Advances the iterator by n elements. Read more
Returns the nth element of the iterator. Read more
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
Takes two iterators and creates a new iterator over both in sequence. Read more
‘Zips up’ two iterators into a single iterator of pairs. Read more
🔬This is a nightly-only experimental API. (iter_intersperse)
Creates a new iterator which places an item generated by separator between adjacent items of the original iterator. Read more
Takes a closure and creates an iterator which calls that closure on each element. Read more
Calls a closure on each element of an iterator. Read more
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
Creates an iterator that both filters and maps. Read more
Creates an iterator which gives the current iteration count as well as the next value. Read more
Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information. Read more
Creates an iterator that skips elements based on a predicate. Read more
Creates an iterator that yields elements based on a predicate. Read more
Creates an iterator that both yields elements based on a predicate and maps. Read more
Creates an iterator that skips the first n elements. Read more
Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner. Read more
An iterator adapter which, like fold, holds internal state, but unlike fold, produces a new iterator. Read more
Creates an iterator that works like map, but flattens nested structure. Read more
Creates an iterator which ends after the first None. Read more
Does something with each element of an iterator, passing the value on. Read more
Borrows an iterator, rather than consuming it. Read more
Transforms an iterator into a collection. Read more
🔬This is a nightly-only experimental API. (iter_collect_into)
Collects all the items from an iterator into a collection. Read more
Consumes an iterator, creating two collections from it. Read more
🔬This is a nightly-only experimental API. (iter_is_partitioned)
Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false. Read more
An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
Folds every element into an accumulator by applying an operation, returning the final result. Read more
Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
🔬This is a nightly-only experimental API. (iterator_try_reduce)
Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more
Tests if every element of the iterator matches a predicate. Read more
Tests if any element of the iterator matches a predicate. Read more
Searches for an element of an iterator that satisfies a predicate. Read more
Applies function to the elements of iterator and returns the first non-none result. Read more
🔬This is a nightly-only experimental API. (try_find)
Applies function to the elements of iterator and returns the first true result or the first error. Read more
Searches for an element in an iterator, returning its index. Read more
Returns the element that gives the maximum value from the specified function. Read more
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
Returns the element that gives the minimum value from the specified function. Read more
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
Converts an iterator of pairs into a pair of containers. Read more
Creates an iterator which copies all of its elements. Read more
Creates an iterator which clones all of its elements. Read more
🔬This is a nightly-only experimental API. (iter_array_chunks)
Returns an iterator over N elements of the iterator at a time. Read more
Sums the elements of an iterator. Read more
Iterates over the entire iterator, multiplying all the elements Read more
🔬This is a nightly-only experimental API. (iter_order_by)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
Lexicographically compares the elements of this Iterator with those of another. Read more
🔬This is a nightly-only experimental API. (iter_order_by)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
Determines if the elements of this Iterator are equal to those of another. Read more
🔬This is a nightly-only experimental API. (iter_order_by)
Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function. Read more
Determines if the elements of this Iterator are unequal to those of another. Read more
Determines if the elements of this Iterator are lexicographically less than those of another. Read more
Determines if the elements of this Iterator are lexicographically less or equal to those of another. Read more
Determines if the elements of this Iterator are lexicographically greater than those of another. Read more
Determines if the elements of this Iterator are lexicographically greater than or equal to those of another. Read more
🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given comparator function. Read more
🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given key extraction function. Read more

Initializes a CertParser from a Reader.

Initializes a CertParser from a File.

Initializes a CertParser from a byte string.

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more
Should always be Self
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.