1package links // import "github.com/docker/docker/daemon/links"
2
3import (
4	"fmt"
5	"path"
6	"strings"
7
8	"github.com/docker/go-connections/nat"
9)
10
11// Link struct holds informations about parent/child linked container
12type Link struct {
13	// Parent container IP address
14	ParentIP string
15	// Child container IP address
16	ChildIP string
17	// Link name
18	Name string
19	// Child environments variables
20	ChildEnvironment []string
21	// Child exposed ports
22	Ports []nat.Port
23}
24
25// NewLink initializes a new Link struct with the provided options.
26func NewLink(parentIP, childIP, name string, env []string, exposedPorts map[nat.Port]struct{}) *Link {
27	var (
28		i     int
29		ports = make([]nat.Port, len(exposedPorts))
30	)
31
32	for p := range exposedPorts {
33		ports[i] = p
34		i++
35	}
36
37	return &Link{
38		Name:             name,
39		ChildIP:          childIP,
40		ParentIP:         parentIP,
41		ChildEnvironment: env,
42		Ports:            ports,
43	}
44}
45
46// ToEnv creates a string's slice containing child container informations in
47// the form of environment variables which will be later exported on container
48// startup.
49func (l *Link) ToEnv() []string {
50	env := []string{}
51
52	_, n := path.Split(l.Name)
53	alias := strings.Replace(strings.ToUpper(n), "-", "_", -1)
54
55	if p := l.getDefaultPort(); p != nil {
56		env = append(env, fmt.Sprintf("%s_PORT=%s://%s:%s", alias, p.Proto(), l.ChildIP, p.Port()))
57	}
58
59	//sort the ports so that we can bulk the continuous ports together
60	nat.Sort(l.Ports, func(ip, jp nat.Port) bool {
61		// If the two ports have the same number, tcp takes priority
62		// Sort in desc order
63		return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp")
64	})
65
66	for i := 0; i < len(l.Ports); {
67		p := l.Ports[i]
68		j := nextContiguous(l.Ports, p.Int(), i)
69		if j > i+1 {
70			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_START=%s://%s:%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto(), l.ChildIP, p.Port()))
71			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_ADDR=%s", alias, p.Port(), strings.ToUpper(p.Proto()), l.ChildIP))
72			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PROTO=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto()))
73			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT_START=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Port()))
74
75			q := l.Ports[j]
76			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_END=%s://%s:%s", alias, p.Port(), strings.ToUpper(q.Proto()), q.Proto(), l.ChildIP, q.Port()))
77			env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT_END=%s", alias, p.Port(), strings.ToUpper(q.Proto()), q.Port()))
78
79			i = j + 1
80			continue
81		} else {
82			i++
83		}
84	}
85	for _, p := range l.Ports {
86		env = append(env, fmt.Sprintf("%s_PORT_%s_%s=%s://%s:%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto(), l.ChildIP, p.Port()))
87		env = append(env, fmt.Sprintf("%s_PORT_%s_%s_ADDR=%s", alias, p.Port(), strings.ToUpper(p.Proto()), l.ChildIP))
88		env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Port()))
89		env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PROTO=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto()))
90	}
91
92	// Load the linked container's name into the environment
93	env = append(env, fmt.Sprintf("%s_NAME=%s", alias, l.Name))
94
95	if l.ChildEnvironment != nil {
96		for _, v := range l.ChildEnvironment {
97			parts := strings.SplitN(v, "=", 2)
98			if len(parts) < 2 {
99				continue
100			}
101			// Ignore a few variables that are added during docker build (and not really relevant to linked containers)
102			if parts[0] == "HOME" || parts[0] == "PATH" {
103				continue
104			}
105			env = append(env, fmt.Sprintf("%s_ENV_%s=%s", alias, parts[0], parts[1]))
106		}
107	}
108	return env
109}
110
111func nextContiguous(ports []nat.Port, value int, index int) int {
112	if index+1 == len(ports) {
113		return index
114	}
115	for i := index + 1; i < len(ports); i++ {
116		if ports[i].Int() > value+1 {
117			return i - 1
118		}
119
120		value++
121	}
122	return len(ports) - 1
123}
124
125// Default port rules
126func (l *Link) getDefaultPort() *nat.Port {
127	var p nat.Port
128	i := len(l.Ports)
129
130	if i == 0 {
131		return nil
132	} else if i > 1 {
133		nat.Sort(l.Ports, func(ip, jp nat.Port) bool {
134			// If the two ports have the same number, tcp takes priority
135			// Sort in desc order
136			return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp")
137		})
138	}
139	p = l.Ports[0]
140	return &p
141}
142