1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133

#[cfg(test)]
mod external_ip_mapper_test;

use std::collections::HashMap;
use std::net::IpAddr;

use crate::candidate::*;
use crate::error::*;

pub(crate) fn validate_ip_string(ip_str: &str) -> Result<IpAddr> {
    match ip_str.parse() {
        Ok(ip) => Ok(ip),
        Err(_) => Err(Error::ErrInvalidNat1to1IpMapping),
    }
}

/// Holds the mapping of local and external IP address for a particular IP family.
#[derive(Default, PartialEq, Debug)]
pub(crate) struct IpMapping {
    ip_sole: Option<IpAddr>, // when non-nil, this is the sole external IP for one local IP assumed
    ip_map: HashMap<String, IpAddr>, // local-to-external IP mapping (k: local, v: external)
}

impl IpMapping {
    pub(crate) fn set_sole_ip(&mut self, ip: IpAddr) -> Result<()> {
        if self.ip_sole.is_some() || !self.ip_map.is_empty() {
            return Err(Error::ErrInvalidNat1to1IpMapping);
        }

        self.ip_sole = Some(ip);

        Ok(())
    }

    pub(crate) fn add_ip_mapping(&mut self, loc_ip: IpAddr, ext_ip: IpAddr) -> Result<()> {
        if self.ip_sole.is_some() {
            return Err(Error::ErrInvalidNat1to1IpMapping);
        }

        let loc_ip_str = loc_ip.to_string();

        // check if dup of local IP
        if self.ip_map.contains_key(&loc_ip_str) {
            return Err(Error::ErrInvalidNat1to1IpMapping);
        }

        self.ip_map.insert(loc_ip_str, ext_ip);

        Ok(())
    }

    pub(crate) fn find_external_ip(&self, loc_ip: IpAddr) -> Result<IpAddr> {
        if let Some(ip_sole) = &self.ip_sole {
            return Ok(*ip_sole);
        }

        self.ip_map.get(&loc_ip.to_string()).map_or_else(
            || Err(Error::ErrExternalMappedIpNotFound),
            |ext_ip| Ok(*ext_ip),
        )
    }
}

#[derive(Default)]
pub(crate) struct ExternalIpMapper {
    pub(crate) ipv4_mapping: IpMapping,
    pub(crate) ipv6_mapping: IpMapping,
    pub(crate) candidate_type: CandidateType,
}

impl ExternalIpMapper {
    pub(crate) fn new(mut candidate_type: CandidateType, ips: &[String]) -> Result<Option<Self>> {
        if ips.is_empty() {
            return Ok(None);
        }
        if candidate_type == CandidateType::Unspecified {
            candidate_type = CandidateType::Host; // defaults to host
        } else if candidate_type != CandidateType::Host
            && candidate_type != CandidateType::ServerReflexive
        {
            return Err(Error::ErrUnsupportedNat1to1IpCandidateType);
        }

        let mut m = Self {
            ipv4_mapping: IpMapping::default(),
            ipv6_mapping: IpMapping::default(),
            candidate_type,
        };

        for ext_ip_str in ips {
            let ip_pair: Vec<&str> = ext_ip_str.split('/').collect();
            if ip_pair.is_empty() || ip_pair.len() > 2 {
                return Err(Error::ErrInvalidNat1to1IpMapping);
            }

            let ext_ip = validate_ip_string(ip_pair[0])?;
            if ip_pair.len() == 1 {
                if ext_ip.is_ipv4() {
                    m.ipv4_mapping.set_sole_ip(ext_ip)?;
                } else {
                    m.ipv6_mapping.set_sole_ip(ext_ip)?;
                }
            } else {
                let loc_ip = validate_ip_string(ip_pair[1])?;
                if ext_ip.is_ipv4() {
                    if !loc_ip.is_ipv4() {
                        return Err(Error::ErrInvalidNat1to1IpMapping);
                    }

                    m.ipv4_mapping.add_ip_mapping(loc_ip, ext_ip)?;
                } else {
                    if loc_ip.is_ipv4() {
                        return Err(Error::ErrInvalidNat1to1IpMapping);
                    }

                    m.ipv6_mapping.add_ip_mapping(loc_ip, ext_ip)?;
                }
            }
        }

        Ok(Some(m))
    }

    pub(crate) fn find_external_ip(&self, local_ip_str: &str) -> Result<IpAddr> {
        let loc_ip = validate_ip_string(local_ip_str)?;

        if loc_ip.is_ipv4() {
            self.ipv4_mapping.find_external_ip(loc_ip)
        } else {
            self.ipv6_mapping.find_external_ip(loc_ip)
        }
    }
}