### Initialize and run a DHCP server

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/index.html

Demonstrates the basic setup for a DHCP server using a configuration file and the Tokio runtime.

```rust
use dhcplease::{Config, DhcpServer};

#[tokio::main]
async fn main() -> dhcplease::Result<()> {
    let config = Config::load_or_create("config.json").await?;
    let server = DhcpServer::new(config).await?;
    server.run().await
}
```

--------------------------------

### DhcpServer::run

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/index.html

Starts the DHCP server to listen for incoming requests on UDP port 67.

```APIDOC
## DhcpServer::run()

### Description
Starts the main server loop, listening for DHCP packets on UDP port 67.

### Signature
`pub async fn run(self) -> Result<()>`
```

--------------------------------

### Initialize and run a DHCP server

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/struct.DhcpServer.html

Demonstrates creating a new server instance, setting up a graceful shutdown trigger using ctrl+c, and starting the server loop.

```rust
use dhcplease::{Config, DhcpServer};

#[tokio::main]
async fn main() -> dhcplease::Result<()> {
    let config = Config::load_or_create("config.json").await?;
    let server = DhcpServer::new(config).await?;

    // Shutdown on ctrl+c
    let shutdown_handle = server.clone();
    tokio::spawn(async move {
        tokio::signal::ctrl_c().await.ok();
        shutdown_handle.shutdown().await;
    });

    server.run().await
}
```

```rust
use dhcplease::{Config, DhcpServer};

#[tokio::main]
async fn main() -> dhcplease::Result<()> {
    let config = Config::load_or_create("config.json").await?;
    let server = DhcpServer::new(config).await?;

    // Shutdown after ctrl+c
    let server_handle = server.clone();
    tokio::spawn(async move {
        tokio::signal::ctrl_c().await.ok();
        server_handle.shutdown().await;
    });

    server.run().await
}
```

--------------------------------

### Cloning Result Contents

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Examples of cloning the contents of a Result containing a reference.

```rust
let val = 12;
let x: Result<&i32, i32> = Ok(&val);
assert_eq!(x, Ok(&12));
let cloned = x.cloned();
assert_eq!(cloned, Ok(12));
```

```rust
let mut val = 12;
let x: Result<&mut i32, i32> = Ok(&mut val);
assert_eq!(x, Ok(&mut 12));
let cloned = x.cloned();
assert_eq!(cloned, Ok(12));
```

--------------------------------

### DhcpServer::run

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/struct.DhcpServer.html

Starts the DHCP server loop to process incoming packets until a shutdown is requested.

```APIDOC
## pub async fn run(&self) -> Result<()>

### Description
Runs the DHCP server, processing packets until shutdown is requested. This method spawns a new async task for each received packet.
```

--------------------------------

### Define DHCP Server Configuration

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/index.html

Example JSON structure for configuring server IP, subnet, address pools, and lease settings.

```json
{
  "server_ip": "192.168.1.1",
  "subnet_mask": "255.255.255.0",
  "pool_start": "192.168.1.100",
  "pool_end": "192.168.1.200",
  "gateway": "192.168.1.1",
  "dns_servers": ["8.8.8.8"],
  "lease_duration_seconds": 86400,
  "leases_file": "leases.json"
}
```

--------------------------------

### Copying Result Contents

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Examples of copying the contents of a Result containing a reference.

```rust
let val = 12;
let x: Result<&i32, i32> = Ok(&val);
assert_eq!(x, Ok(&12));
let copied = x.copied();
assert_eq!(copied, Ok(12));
```

```rust
let mut val = 12;
let x: Result<&mut i32, i32> = Ok(&mut val);
assert_eq!(x, Ok(&mut 12));
let copied = x.copied();
assert_eq!(copied, Ok(12));
```

--------------------------------

### Flattening Nested Results

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Examples of flattening nested Result types.

```rust
let x: Result<Result<&'static str, u32>, u32> = Ok(Ok("hello"));
assert_eq!(Ok("hello"), x.flatten());

let x: Result<Result<&'static str, u32>, u32> = Ok(Err(6));
assert_eq!(Err(6), x.flatten());

let x: Result<Result<&'static str, u32>, u32> = Err(6);
assert_eq!(Err(6), x.flatten());
```

```rust
let x: Result<Result<Result<&'static str, u32>, u32>, u32> = Ok(Ok(Ok("hello")));
assert_eq!(Ok(Ok("hello")), x.flatten());
assert_eq!(Ok("hello"), x.flatten().flatten());
```

--------------------------------

### Transposing Result and Option

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Example of transposing a Result of an Option into an Option of a Result.

```rust
#[derive(Debug, Eq, PartialEq)]
struct SomeErr;

let x: Result<Option<i32>, SomeErr> = Ok(Some(5));
let y: Option<Result<i32, SomeErr>> = Some(Ok(5));
assert_eq!(x.transpose(), y);
```

--------------------------------

### Checking Result Status

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Examples of checking if a Result is Ok or Err.

```rust
let x: Result<i32, &str> = Ok(-3);
assert_eq!(x.is_ok(), true);

let x: Result<i32, &str> = Err("Some error message");
assert_eq!(x.is_ok(), false);
```

```rust
let x: Result<i32, &str> = Ok(-3);
assert_eq!(x.is_err(), false);

let x: Result<i32, &str> = Err("Some error message");
assert_eq!(x.is_err(), true);
```

--------------------------------

### Validating Result with Predicate

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Example of using is_ok_and to validate the value inside a Result.

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.is_ok_and(|x| x > 1), true);

let x: Result<u32, &str> = Ok(0);
assert_eq!(x.is_ok_and(|x| x > 1), false);

let x: Result<u32, &str> = Err("hey");
assert_eq!(x.is_ok_and(|x| x > 1), false);

let x: Result<String, &str> = Ok("ownership".to_string());
assert_eq!(x.as_ref().is_ok_and(|x| x.len() > 1), true);
println!("still alive {:?}", x);
```

--------------------------------

### Get Remaining Lease Time

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Lease.html

Calculates the remaining seconds until the lease expires, returning 0 if it has already expired.

```rust
pub fn remaining_seconds(&self) -> i64
```

--------------------------------

### Initialize and Allocate IP with Leases

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Leases.html

Demonstrates creating a new Leases instance from a configuration and allocating an IP address for a specific client ID.

```rust
use std::sync::Arc;
use dhcplease::{Config, Leases};

let config = Arc::new(Config::default());
let leases = Leases::new(config).await?;

let client_id = vec![1, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff];
let ip = leases.allocate_ip(&client_id).await?;
```

--------------------------------

### DhcpServer::new

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/index.html

Initializes a new DHCP server instance using the provided configuration.

```APIDOC
## DhcpServer::new(config: Config)

### Description
Creates a new instance of the DHCP server using the provided configuration object.

### Signature
`pub async fn new(config: Config) -> Result<Self>`

### Parameters
- **config** (Config) - Required - The server configuration including IP pool, lease duration, and DNS settings.
```

--------------------------------

### load_or_create

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Loads configuration from a file, or creates a default config if it doesn't exist.

```APIDOC
## pub async fn load_or_create<P: AsRef<Path>>(path: P) -> Result<Self>

### Description
Loads configuration from a file, or creates a default config if it doesn't exist.

### Arguments
- **path** (P) - Path to the JSON configuration file

### Errors
Returns an error if the file exists but cannot be read or parsed, the configuration fails validation, or a new default config cannot be written.
```

--------------------------------

### save

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Saves the configuration to a JSON file with pretty-printing.

```APIDOC
## pub async fn save<P: AsRef<Path>>(&self, path: P) -> Result<()>

### Description
Saves the configuration to a JSON file. The file is written with pretty-printing for human readability.
```

--------------------------------

### Lease Constructor

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Lease.html

Creates a new lease instance, initializing timestamps based on the current time and the provided duration.

```rust
pub fn new( ip_address: Ipv4Addr, client_id: String, duration_seconds: u32, ) -> Self
```

--------------------------------

### Define DHCP server configuration

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

The Config struct contains fields for network parameters, IP allocation ranges, and lease management settings.

```rust
pub struct Config {Show 15 fields
    pub server_ip: Ipv4Addr,
    pub subnet_mask: Ipv4Addr,
    pub pool_start: Ipv4Addr,
    pub pool_end: Ipv4Addr,
    pub gateway: Option<Ipv4Addr>,
    pub dns_servers: Vec<Ipv4Addr>,
    pub domain_name: Option<String>,
    pub lease_duration_seconds: u32,
    pub renewal_time_seconds: Option<u32>,
    pub rebinding_time_seconds: Option<u32>,
    pub broadcast_address: Option<Ipv4Addr>,
    pub mtu: Option<u16>,
    pub static_bindings: Vec<StaticBinding>,
    pub leases_file: String,
    pub interface_index: Option<u32>,
}
```

--------------------------------

### Define BOOTREPLY constant

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/constant.BOOTREPLY.html

Represents the BOOTP/DHCP operation code for server replies.

```rust
pub const BOOTREPLY: u8 = 2;
```

--------------------------------

### DhcpPacket Factory Methods

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/struct.DhcpPacket.html

Methods for creating reply packets based on existing requests.

```APIDOC
## pub fn create_reply(request: &DhcpPacket, message_type: MessageType, your_ip: Ipv4Addr, server_ip: Ipv4Addr, options: Vec<DhcpOption>) -> Self

Creates a DHCP reply packet (OFFER, ACK, or NAK) from a request, automatically copying transaction fields and adding the message type option.

## pub fn create_bootp_reply(request: &DhcpPacket, your_ip: Ipv4Addr, server_ip: Ipv4Addr, options: Vec<DhcpOption>) -> Self

Creates a legacy BOOTP reply packet without the DHCP message type option.
```

--------------------------------

### Calculate Product of Result Iterator

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Demonstrates using the product method on an iterator of Results, which short-circuits on the first Err encountered.

```rust
let nums = vec!["5", "10", "1", "2"];
let total: Result<usize, _> = nums.iter().map(|w| w.parse::<usize>()).product();
assert_eq!(total, Ok(100));
let nums = vec!["5", "10", "one", "2"];
let total: Result<usize, _> = nums.iter().map(|w| w.parse::<usize>()).product();
assert!(total.is_err());
```

--------------------------------

### StaticBinding Struct Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.StaticBinding.html

The structure definition for a static MAC-to-IP binding.

```rust
pub struct StaticBinding {
    pub mac_address: String,
    pub ip_address: Ipv4Addr,
    pub hostname: Option<String>,
}
```

--------------------------------

### Fallback to alternative Result with or

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the current Result if it is Ok, otherwise returns the provided alternative Result.

```rust
let x: Result<u32, &str> = Ok(2);
let y: Result<u32, &str> = Err("late error");
assert_eq!(x.or(y), Ok(2));

let x: Result<u32, &str> = Err("early error");
let y: Result<u32, &str> = Ok(2);
assert_eq!(x.or(y), Ok(2));

let x: Result<u32, &str> = Err("not a 2");
let y: Result<u32, &str> = Err("late error");
assert_eq!(x.or(y), Err("late error"));

let x: Result<u32, &str> = Ok(2);
let y: Result<u32, &str> = Ok(100);
assert_eq!(x.or(y), Ok(2));
```

--------------------------------

### validate

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Validates the configuration for correctness.

```APIDOC
## pub fn validate(&self) -> Result<()>

### Description
Validates the configuration for correctness, checking pool ranges, IP conflicts, subnet masks, and static bindings.

### Errors
Returns Error::InvalidConfig with a description of the first validation failure encountered.
```

--------------------------------

### DhcpServer::save_leases

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/struct.DhcpServer.html

Persists the current lease state to disk.

```APIDOC
## pub async fn save_leases(&self) -> Result<()>

### Description
Saves all leases to disk immediately. Call this before shutting down to ensure lease state is persisted.
```

--------------------------------

### Convert Result to References

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Creates a new Result containing references to the original values.

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.as_ref(), Ok(&2));

let x: Result<u32, &str> = Err("Error");
assert_eq!(x.as_ref(), Err(&"Error"));
```

```rust
fn mutate(r: &mut Result<i32, i32>) {
    match r.as_mut() {
        Ok(v) => *v = 42,
        Err(e) => *e = 0,
    }
}

let mut x: Result<i32, i32> = Ok(2);
mutate(&mut x);
assert_eq!(x.unwrap(), 42);

let mut x: Result<i32, i32> = Err(13);
mutate(&mut x);
assert_eq!(x.unwrap_err(), 0);
```

--------------------------------

### Provide default value with unwrap_or

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the contained Ok value or a provided default value if the result is Err.

```rust
let default = 2;
let x: Result<u32, &str> = Ok(9);
assert_eq!(x.unwrap_or(default), 9);

let x: Result<u32, &str> = Err("error");
assert_eq!(x.unwrap_or(default), default);
```

--------------------------------

### encode()

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.DhcpOption.html

Encodes the DHCP option into its wire format.

```APIDOC
## pub fn encode(&self) -> Vec<u8>

### Description
Encodes the option to its wire format (code + length + data). The returned bytes can be directly appended to a DHCP packet’s options section.

### Returns
- **Vec<u8>** - The encoded byte representation of the option.
```

--------------------------------

### pub fn normalize_mac(mac: &str) -> String

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/fn.normalize_mac.html

Normalizes a given MAC address string to a lowercase colon-separated format (e.g., 'aa:bb:cc:dd:ee:ff').

```APIDOC
## Function: normalize_mac

### Description
Normalizes a MAC address string to lowercase colon-separated format. It converts formats like "AA-BB-CC-DD-EE-FF" to "aa:bb:cc:dd:ee:ff".

### Signature
`pub fn normalize_mac(mac: &str) -> String`

### Parameters
- **mac** (&str) - The input MAC address string to be normalized.

### Returns
- **String** - The normalized MAC address in lowercase colon-separated format.
```

--------------------------------

### Into Ok Value

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Extracts the Ok value without risk of panicking, useful for infallible Result types.

```rust

fn only_good_news() -> Result<String, !> {
    Ok("this is fine".into())
}

let s: String = only_good_news().into_ok();
println!("{s}");
```

--------------------------------

### pub fn sanitize_hostname(hostname: &str) -> String

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/fn.sanitize_hostname.html

Sanitizes a hostname string by retaining only ASCII alphanumeric characters, hyphens, and dots, and truncating the result to a maximum of 255 characters.

```APIDOC
## sanitize_hostname

### Description
Sanitizes a hostname by removing invalid characters. Keeps only ASCII alphanumeric characters, hyphens, and dots. Truncates to 255 characters maximum per RFC 1035.

### Signature
`pub fn sanitize_hostname(hostname: &str) -> String`

### Parameters
- **hostname** (&str) - The input hostname string to be sanitized.

### Returns
- **String** - The sanitized hostname.
```

--------------------------------

### LeaseStore Struct Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.LeaseStore.html

The primary structure for storing DHCP lease data, containing maps for leases, IP assignments, and declined IPs.

```rust
pub struct LeaseStore {
    pub leases: HashMap<String, Lease>,
    pub ip_to_client: HashMap<Ipv4Addr, String>,
    pub declined_ips: HashMap<Ipv4Addr, DateTime<Utc>>,
}
```

--------------------------------

### Inspect Result Ok

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Executes a closure with a reference to the Ok value without modifying the result.

```rust
let x: u8 = "4"
    .parse::<u8>()
    .inspect(|x| println!("original: {x}"))
    .map(|x| x.pow(3))
    .expect("failed to parse number");
```

--------------------------------

### Expect Result Value

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the Ok value or panics with a provided message if the result is Err.

```rust
let x: Result<u32, &str> = Err("emergency failure");
x.expect("Testing expect"); // panics with `Testing expect: emergency failure`
```

```rust
let path = std::env::var("IMPORTANT_PATH")
    .expect("env variable `IMPORTANT_PATH` should be set by `wrapper_script.sh`");
```

--------------------------------

### parse(code, data)

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.DhcpOption.html

Parses a DHCP option from its code and raw data bytes.

```APIDOC
## pub fn parse(code: u8, data: &[u8]) -> Result<Self>

### Description
Parses a DHCP option from its code and raw data.

### Parameters
- **code** (u8) - The option code (first byte of TLV).
- **data** (&[u8]) - The option data (after code and length bytes).

### Errors
Returns `Error::InvalidPacket` if the data length is invalid for the option type.
```

--------------------------------

### option_code()

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.DhcpOption.html

Returns the RFC 2132 option code for the current DHCP option.

```APIDOC
## pub fn option_code(&self) -> u8

### Description
Returns the RFC 2132 option code for this option.

### Returns
- **u8** - The option code.
```

--------------------------------

### Collect Result from Iterator

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Demonstrates how collecting an iterator of Results short-circuits on the first Err encountered.

```rust
let v = vec![1, 2];
let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32|
    x.checked_add(1).ok_or("Overflow!")
).collect();
assert_eq!(res, Ok(vec![2, 3]));
```

```rust
let v = vec![1, 2, 0];
let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32|
    x.checked_sub(1).ok_or("Underflow!")
).collect();
assert_eq!(res, Err("Underflow!"));
```

```rust
let v = vec![3, 2, 1, 10];
let mut shared = 0;
let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32| {
    shared += x;
    x.checked_sub(2).ok_or("Underflow!")
}).collect();
assert_eq!(res, Err("Underflow!"));
assert_eq!(shared, 6);
```

--------------------------------

### Leases Struct Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Leases.html

The internal structure definition for the Leases manager.

```rust
pub struct Leases { /* private fields */ }
```

--------------------------------

### Lease Struct Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Lease.html

The primary data structure representing an active DHCP lease with fields for IP, client ID, hostname, and timing metadata.

```rust
pub struct Lease {
    pub ip_address: Ipv4Addr,
    pub client_id: String,
    pub hostname: Option<String>,
    pub expires_at: DateTime<Utc>,
    pub created_at: DateTime<Utc>,
    pub last_seen: DateTime<Utc>,
}
```

--------------------------------

### Map Result to Default or Function

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Provides fallback mechanisms when mapping Result values.

```rust
let x: Result<_, &str> = Ok("foo");
assert_eq!(x.map_or(42, |v| v.len()), 3);

let x: Result<&str, _> = Err("bar");
assert_eq!(x.map_or(42, |v| v.len()), 42);
```

```rust
let k = 21;

let x : Result<_, &str> = Ok("foo");
assert_eq!(x.map_or_else(|e| k * 2, |v| v.len()), 3);

let x : Result<&str, _> = Err("bar");
assert_eq!(x.map_or_else(|e| k * 2, |v| v.len()), 42);
```

```rust
let x: Result<_, &str> = Ok("foo");
let y: Result<&str, _> = Err("bar");

assert_eq!(x.map_or_default(|x| x.len()), 3);
assert_eq!(y.map_or_default(|y| y.len()), 0);
```

--------------------------------

### normalize_mac function signature

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/fn.normalize_mac.html

The function signature for normalizing MAC address strings.

```rust
pub fn normalize_mac(mac: &str) -> String
```

--------------------------------

### And Operation on Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the provided result if the current result is Ok, otherwise returns the Err value.

```rust
let x: Result<u32, &str> = Ok(2);
let y: Result<&str, &str> = Err("late error");
assert_eq!(x.and(y), Err("late error"));

let x: Result<u32, &str> = Err("early error");
let y: Result<&str, &str> = Ok("foo");
assert_eq!(x.and(y), Err("early error"));

let x: Result<u32, &str> = Err("not a 2");
let y: Result<&str, &str> = Err("late error");
assert_eq!(x.and(y), Err("not a 2"));

let x: Result<u32, &str> = Ok(2);
let y: Result<&str, &str> = Ok("different result type");
assert_eq!(x.and(y), Ok("different result type"));
```

--------------------------------

### DhcpServer::shutdown

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/struct.DhcpServer.html

Signals the server to perform a graceful shutdown.

```APIDOC
## pub async fn shutdown(&self)

### Description
Signals the server to shut down gracefully. The server will finish processing the current packet, save leases to disk, and then the run method will return.
```

--------------------------------

### Unwrap Result with Default

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the Ok value or the default value for the type if the result is an Err.

```rust
let good_year_from_input = "1909";
let bad_year_from_input = "190blarg";
let good_year = good_year_from_input.parse().unwrap_or_default();
let bad_year = bad_year_from_input.parse().unwrap_or_default();

assert_eq!(1909, good_year);
assert_eq!(0, bad_year);
```

--------------------------------

### And Then Operation on Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Calls a function if the result is Ok, allowing for chained control flow.

```rust
fn sq_then_to_string(x: u32) -> Result<String, &'static str> {
    x.checked_mul(x).map(|sq| sq.to_string()).ok_or("overflowed")
}
```

--------------------------------

### Map Result Values

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Applies a function to the Ok value of a Result.

```rust
let line = "1\n2\n3\n4\n";

for num in line.lines() {
    match num.parse::<i32>().map(|i| i * 2) {
        Ok(n) => println!("{n}"),
        Err(..) => {}
    }
}
```

--------------------------------

### DhcpPacket Methods

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/struct.DhcpPacket.html

Methods for parsing, encoding, and inspecting DHCP packet data.

```APIDOC
## pub fn parse(data: &[u8]) -> Result<Self>

Parses a DHCP packet from raw bytes. Returns an error if the packet is malformed, has an invalid magic cookie, or violates relay loop protection.

## pub fn encode(&self) -> Vec<u8>

Encodes the packet into a byte buffer for network transmission, including padding and TLV-formatted options.

## pub fn message_type(&self) -> Option<MessageType>

Returns the DHCP message type (Option 53) if present.

## pub fn requested_ip(&self) -> Option<Ipv4Addr>

Returns the requested IP address (Option 50) if present.

## pub fn server_identifier(&self) -> Option<Ipv4Addr>

Returns the server identifier (Option 54) if present.

## pub fn client_identifier(&self) -> Option<&[u8]>

Returns the client identifier (Option 61) if present.

## pub fn relay_agent_info(&self) -> Option<&[u8]>

Returns the relay agent information (Option 82) if present.

## pub fn hostname(&self) -> Option<&str>

Returns the client hostname (Option 12) if present.

## pub fn parameter_request_list(&self) -> Option<&[u8]>

Returns the parameter request list (Option 55) if present.

## pub fn requested_lease_time(&self) -> Option<u32>

Returns the requested lease time (Option 51) if present.

## pub fn chaddr_bytes(&self) -> &[u8]

Returns the client hardware address bytes.

## pub fn format_mac(&self) -> String

Formats the client hardware address as a colon-separated string.

## pub fn client_id(&self) -> Vec<u8>

Returns a unique client identifier for lease tracking, using Option 61 or constructing one from hardware details.

## pub fn is_broadcast(&self) -> bool

Returns true if the broadcast flag is set.
```

--------------------------------

### sanitize_hostname function signature

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/fn.sanitize_hostname.html

The function signature for sanitizing a hostname string.

```rust
pub fn sanitize_hostname(hostname: &str) -> String
```

--------------------------------

### Define HLEN_ETHERNET constant

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/constant.HLEN_ETHERNET.html

Represents the hardware address length for Ethernet, which is 6 bytes.

```rust
pub const HLEN_ETHERNET: u8 = 6;
```

--------------------------------

### is_valid_mac

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Validates a MAC address string format.

```APIDOC
## pub fn is_valid_mac(mac: &str) -> bool

### Description
Validates a MAC address string format. Accepts colon-separated (aa:bb:cc:dd:ee:ff) or hyphen-separated (aa-bb-cc-dd-ee-ff) formats, case-insensitive.
```

--------------------------------

### Compute default value with unwrap_or_else

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the contained Ok value or computes a default value using a closure if the result is Err.

```rust
fn count(x: &str) -> usize { x.len() }
```

--------------------------------

### BOOTREQUEST Constant Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/constant.BOOTREQUEST.html

Defines the BOOTREQUEST constant as a u8 with a value of 1.

```rust
pub const BOOTREQUEST: u8 = 1;
```

--------------------------------

### sanitize_domain_name function signature

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/fn.sanitize_domain_name.html

The function signature for sanitizing domain names in Rust.

```rust
pub fn sanitize_domain_name(domain: &str) -> String
```

--------------------------------

### DHCP_CLIENT_PORT Constant Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/constant.DHCP_CLIENT_PORT.html

Represents the standard DHCP client port value of 68.

```rust
pub const DHCP_CLIENT_PORT: u16 = 68;
```

--------------------------------

### Define HTYPE_ETHERNET constant

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/constant.HTYPE_ETHERNET.html

Represents the hardware type for Ethernet as a u8 value.

```rust
pub const HTYPE_ETHERNET: u8 = 1;
```

--------------------------------

### Unwrap Error from Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the Err value or panics if the result is an Ok.

```rust
let x: Result<u32, &str> = Ok(2);
x.unwrap_err(); // panics with `2`
```

```rust
let x: Result<u32, &str> = Err("emergency failure");
assert_eq!(x.unwrap_err(), "emergency failure");
```

--------------------------------

### Calculate Sum of Result Iterator

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Demonstrates using the sum method on an iterator of Results, which returns an Err if any element is an Err.

```rust
let f = |&x: &i32| if x < 0 { Err("Negative element found") } else { Ok(x) };
let v = vec![1, 2];
let res: Result<i32, _> = v.iter().map(f).sum();
assert_eq!(res, Ok(3));
let v = vec![1, -2];
let res: Result<i32, _> = v.iter().map(f).sum();
assert_eq!(res, Err("Negative element found"));
```

--------------------------------

### DhcpOption Enum Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.DhcpOption.html

The structure of the DhcpOption enum, containing variants for various DHCP configuration options.

```rust
pub enum DhcpOption {
Show 18 variants    SubnetMask(Ipv4Addr),
    Router(Vec<Ipv4Addr>),
    DnsServer(Vec<Ipv4Addr>),
    Hostname(String),
    DomainName(String),
    BroadcastAddress(Ipv4Addr),
    RequestedIpAddress(Ipv4Addr),
    LeaseTime(u32),
    OptionOverload(OverloadFlag),
    MessageType(MessageType),
    ServerIdentifier(Ipv4Addr),
    ParameterRequestList(Vec<u8>),
    RenewalTime(u32),
    RebindingTime(u32),
    ClientIdentifier(Vec<u8>),
    RelayAgentInfo(Vec<u8>),
    InterfaceMtu(u16),
    Unknown(u8, Vec<u8>),
}
```

--------------------------------

### calculate_broadcast

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Returns the broadcast address for the configured network.

```APIDOC
## pub fn calculate_broadcast(&self) -> Ipv4Addr

### Description
Returns the broadcast address for the configured network. If broadcast_address is explicitly configured, returns that value; otherwise, calculates it from server_ip and subnet_mask.
```

--------------------------------

### Convert Result to Option

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Converts a Result into an Option, discarding the error or success value respectively.

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.ok(), Some(2));

let x: Result<u32, &str> = Err("Nothing here");
assert_eq!(x.ok(), None);
```

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.err(), None);

let x: Result<u32, &str> = Err("Nothing here");
assert_eq!(x.err(), Some("Nothing here"));
```

--------------------------------

### Expect Error from Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns the Err value or panics with a custom message if the result is an Ok.

```rust
let x: Result<u32, &str> = Ok(10);
x.expect_err("Testing expect_err"); // panics with `Testing expect_err: 10`
```

--------------------------------

### Lease Expiration Check

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Lease.html

Checks if the current lease has passed its expiration time.

```rust
pub fn is_expired(&self) -> bool
```

--------------------------------

### Result Type Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

The core definition of the Result type alias.

```rust
pub type Result<T> = Result<T, Error>;
```

```rust
pub enum Result<T> {
    Ok(T),
    Err(Error),
}
```

--------------------------------

### pool_size

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Returns the total number of addresses in the pool.

```APIDOC
## pub fn pool_size(&self) -> u32

### Description
Returns the total number of addresses in the pool.
```

--------------------------------

### DHCP_SERVER_PORT Constant Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/server/constant.DHCP_SERVER_PORT.html

Represents the standard DHCP server port value of 67.

```rust
pub const DHCP_SERVER_PORT: u16 = 67;
```

--------------------------------

### DhcpPacket Struct Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/packet/struct.DhcpPacket.html

The structure definition for a parsed DHCP packet, containing header fields and a vector of DHCP options.

```rust
pub struct DhcpPacket {Show 15 fields
    pub op: u8,
    pub htype: u8,
    pub hlen: u8,
    pub hops: u8,
    pub xid: u32,
    pub secs: u16,
    pub flags: u16,
    pub ciaddr: Ipv4Addr,
    pub yiaddr: Ipv4Addr,
    pub siaddr: Ipv4Addr,
    pub giaddr: Ipv4Addr,
    pub chaddr: [u8; 16],
    pub sname: [u8; 64],
    pub file: [u8; 128],
    pub options: Vec<DhcpOption>,
}
```

--------------------------------

### OptionCode Enum Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.OptionCode.html

The OptionCode enum uses a u8 representation for DHCP option codes. It includes common options like SubnetMask, Router, and LeaseTime.

```rust
#[repr(u8)]
pub enum OptionCode {
Show 19 variants    Pad = 0,
    SubnetMask = 1,
    Router = 3,
    DnsServer = 6,
    Hostname = 12,
    DomainName = 15,
    InterfaceMtu = 26,
    BroadcastAddress = 28,
    RequestedIpAddress = 50,
    LeaseTime = 51,
    OptionOverload = 52,
    MessageType = 53,
    ServerIdentifier = 54,
    ParameterRequestList = 55,
    RenewalTime = 58,
    RebindingTime = 59,
    ClientIdentifier = 61,
    RelayAgentInfo = 82,
    End = 255,
}
```

--------------------------------

### Unwrap Result Value

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Extracts the Ok value or panics if the result is an Err. Discouraged in favor of pattern matching or the ? operator.

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(x.unwrap(), 2);
```

```rust
let x: Result<u32, &str> = Err("emergency failure");
x.unwrap(); // panics with `emergency failure`
```

--------------------------------

### Check Result Error with Predicate

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Uses is_err_and to verify if a Result is an Err and satisfies a specific condition.

```rust
use std::io::{Error, ErrorKind};

let x: Result<u32, Error> = Err(Error::new(ErrorKind::NotFound, "!"));
assert_eq!(x.is_err_and(|x| x.kind() == ErrorKind::NotFound), true);

let x: Result<u32, Error> = Err(Error::new(ErrorKind::PermissionDenied, "!"));
assert_eq!(x.is_err_and(|x| x.kind() == ErrorKind::NotFound), false);

let x: Result<u32, Error> = Ok(123);
assert_eq!(x.is_err_and(|x| x.kind() == ErrorKind::NotFound), false);

let x: Result<u32, String> = Err("ownership".to_string());
assert_eq!(x.as_ref().is_err_and(|x| x.len() > 1), true);
println!("still alive {:?}", x);
```

--------------------------------

### Chain fallible operations with and_then

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Chains operations that return a Result, propagating errors if they occur.

```rust
assert_eq!(Ok(2).and_then(sq_then_to_string), Ok(4.to_string()));
assert_eq!(Ok(1_000_000).and_then(sq_then_to_string), Err("overflowed"));
assert_eq!(Err("not a number").and_then(sq_then_to_string), Err("not a number"));
```

```rust
use std::{io::ErrorKind, path::Path};

// Note: on Windows "/" maps to "C:\"
let root_modified_time = Path::new("/").metadata().and_then(|md| md.modified());
assert!(root_modified_time.is_ok());

let should_fail = Path::new("/bad/path").metadata().and_then(|md| md.modified());
assert!(should_fail.is_err());
assert_eq!(should_fail.unwrap_err().kind(), ErrorKind::NotFound);
```

--------------------------------

### Convert Result to Iterator

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Converts a Result into an iterator that yields the contained value if Ok, or nothing if Err.

```rust
let x: Result<u32, &str> = Ok(5);
let v: Vec<u32> = x.into_iter().collect();
assert_eq!(v, [5]);

let x: Result<u32, &str> = Err("nothing!");
let v: Vec<u32> = x.into_iter().collect();
assert_eq!(v, []);
```

--------------------------------

### Iterate Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns an iterator over the contained value if the result is Ok.

```rust
let x: Result<u32, &str> = Ok(7);
assert_eq!(x.iter().next(), Some(&7));

let x: Result<u32, &str> = Err("nothing!");
assert_eq!(x.iter().next(), None);
```

--------------------------------

### Renew Lease

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/lease/struct.Lease.html

Extends the lease duration, updating the expiration and last seen timestamps to the current time.

```rust
pub fn renew(&mut self, duration_seconds: u32)
```

--------------------------------

### Fallback to closure result with or_else

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Calls a closure to produce an alternative Result if the current one is Err.

```rust
fn sq(x: u32) -> Result<u32, u32> { Ok(x * x) }
fn err(x: u32) -> Result<u32, u32> { Err(x) }

assert_eq!(Ok(2).or_else(sq).or_else(sq), Ok(2));
assert_eq!(Ok(2).or_else(err).or_else(sq), Ok(2));
assert_eq!(Err(3).or_else(sq).or_else(err), Ok(9));
assert_eq!(Err(3).or_else(err).or_else(err), Err(3));
```

--------------------------------

### ip_in_pool

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/config/struct.Config.html

Checks if an IP address is within the configured pool range.

```APIDOC
## pub fn ip_in_pool(&self, ip: Ipv4Addr) -> bool

### Description
Checks if an IP address is within the configured pool range. Returns true if pool_start <= ip <= pool_end.
```

--------------------------------

### Unwrap Result Unchecked

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Accesses the Ok value without checking for Err. Calling this on an Err variant results in undefined behavior.

```rust
let x: Result<u32, &str> = Ok(2);
assert_eq!(unsafe { x.unwrap_unchecked() }, 2);
```

```rust
let x: Result<u32, &str> = Err("emergency failure");
unsafe { x.unwrap_unchecked() }; // Undefined behavior!
```

--------------------------------

### Into Error Value

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Extracts the Err value without risk of panicking, useful for infallible Result types.

```rust

fn only_bad_news() -> Result<!, String> {
    Err("Oops, it failed".into())
}

let error: String = only_bad_news().into_err();
println!("{error}");
```

--------------------------------

### Error Enum Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/enum.Error.html

The Error enum variants cover network, configuration, and protocol-level errors encountered by the DHCP server.

```rust
pub enum Error {
    Io(Error),
    Json(Error),
    InvalidPacket(String),
    PoolExhausted,
    InvalidConfig(String),
    Socket(String),
    AddressOutOfRange(Ipv4Addr),
    LeaseNotFound(String),
}
```

--------------------------------

### Map Result Error

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Transforms the error variant of a Result while keeping the Ok variant unchanged.

```rust
fn stringify(x: u32) -> String { format!("error code: {x}") }

let x: Result<u32, u32> = Ok(2);
assert_eq!(x.map_err(stringify), Ok(2));

let x: Result<u32, u32> = Err(13);
assert_eq!(x.map_err(stringify), Err("error code: 13".to_string()));
```

--------------------------------

### Inspect Result Err

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Executes a closure with a reference to the Err value without modifying the result.

```rust
use std::{fs, io};

fn read() -> io::Result<String> {
    fs::read_to_string("address.txt")
        .inspect_err(|e| eprintln!("failed to read file: {e}"))
}
```

--------------------------------

### Unwrap Err Unchecked

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Accesses the Err value without checking for Ok. Calling this on an Ok variant results in undefined behavior.

```rust
let x: Result<u32, &str> = Ok(2);
unsafe { x.unwrap_err_unchecked() }; // Undefined behavior!
```

```rust
let x: Result<u32, &str> = Err("emergency failure");
assert_eq!(unsafe { x.unwrap_err_unchecked() }, "emergency failure");
```

--------------------------------

### Iterate Mut Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Returns a mutable iterator over the contained value if the result is Ok.

```rust
let mut x: Result<u32, &str> = Ok(7);
match x.iter_mut().next() {
    Some(v) => *v = 40,
    None => {},
}
assert_eq!(x, Ok(40));

let mut x: Result<u32, &str> = Err("nothing!");
assert_eq!(x.iter_mut().next(), None);
```

--------------------------------

### OverloadFlag Enum Definition

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.OverloadFlag.html

The definition of the OverloadFlag enum, which uses a u8 representation to map specific fields to option-carrying roles.

```rust
#[repr(u8)]
pub enum OverloadFlag {
    File = 1,
    Sname = 2,
    Both = 3,
}
```

--------------------------------

### Deref Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Converts a Result containing a dereferenceable type into a Result containing a reference to the target.

```rust
let x: Result<String, u32> = Ok("hello".to_string());
let y: Result<&str, &u32> = Ok("hello");
assert_eq!(x.as_deref(), y);

let x: Result<String, u32> = Err(42);
let y: Result<&str, &u32> = Err(&42);
assert_eq!(x.as_deref(), y);
```

--------------------------------

### Define MessageType Enum

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/options/enum.MessageType.html

The MessageType enum uses a u8 representation to map DHCP message types to their corresponding protocol values.

```rust
#[repr(u8)]
pub enum MessageType {
    Discover = 1,
    Offer = 2,
    Request = 3,
    Decline = 4,
    Ack = 5,
    Nak = 6,
    Release = 7,
    Inform = 8,
}
```

--------------------------------

### Deref Mut Result

Source: https://docs.rs/dhcplease/0.2.1/dhcplease/error/type.Result.html

Converts a Result containing a mutable dereferenceable type into a Result containing a mutable reference to the target.

```rust
let mut s = "HELLO".to_string();
let mut x: Result<String, u32> = Ok("hello".to_string());
let y: Result<&mut str, &mut u32> = Ok(&mut s);
assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y);

let mut i = 42;
let mut x: Result<String, u32> = Err(42);
let y: Result<&mut str, &mut u32> = Err(&mut i);
assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y);
```

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