Try all ip addresses when establishing a connection

Fixes JuliaWeb#672
Reenables JuliaWeb#428

src/ConnectionPool.jl

@@ -648,37 +648,52 @@ function getconnection(::Type{TCPSocket},
 
     @debug 2 "TCP connect: $host:$p..."
 
+    addrs = Sockets.getalladdrinfo(host)
+
     connect_timeout = connect_timeout == 0 && readtimeout > 0 ? readtimeout : connect_timeout
-    if connect_timeout == 0
-        tcp = Sockets.connect(host == "localhost" ? ip"127.0.0.1" : Sockets.getalladdrinfo(host)[1], p)
-        keepalive && keepalive!(tcp)
-        return tcp
-    end
 
-    tcp = Sockets.TCPSocket()
-    Sockets.connect!(tcp, Sockets.getalladdrinfo(host)[1], p)
-
-    timeout = Ref{Bool}(false)
-    @async begin
-        sleep(connect_timeout)
-        if tcp.status == Base.StatusConnecting
-            timeout[] = true
-            tcp.status = Base.StatusClosing
-            ccall(:jl_forceclose_uv, Nothing, (Ptr{Nothing},), tcp.handle)
-            #close(tcp)
-        end
-    end
-    try
-        Sockets.wait_connected(tcp)
-    catch e
-        if timeout[]
-            throw(ConnectTimeout(host, port))
+    lasterr = ErrorException("unknown connection error")
+
+    for addr in addrs
+        if connect_timeout == 0
+            try
+                tcp = Sockets.connect(addr, p)
+                keepalive && keepalive!(tcp)
+                return tcp
+            catch err
+                lasterr = err
+                continue # to next ip addr
+            end
+        else
+            tcp = Sockets.TCPSocket()
+            Sockets.connect!(tcp, addr, p)
+
+            timeout = Ref{Bool}(false)
+            @async begin
+                sleep(connect_timeout)
+                if tcp.status == Base.StatusConnecting
+                    timeout[] = true
+                    tcp.status = Base.StatusClosing
+                    ccall(:jl_forceclose_uv, Nothing, (Ptr{Nothing},), tcp.handle)
+                    #close(tcp)
+                end
+            end
+            try
+                Sockets.wait_connected(tcp)
+                keepalive && keepalive!(tcp)
+                return tcp
+            catch err
+                if timeout[]
+                    lasterr = ConnectTimeout(host, port)
+                else
+                    lasterr = err
+                end
+                continue # to next ip addr
+            end
         end
-        rethrow(e)
     end
-
-    keepalive && keepalive!(tcp)
-    return tcp
+    # If no connetion could be set up, to any address, throw last error
+    throw(lasterr)
 end
 
 const nosslconfig = SSLConfig()

test/client.jl

@@ -1,5 +1,6 @@
 using ..TestRequest
 using HTTP
+using Sockets
 using JSON
 using Test
 
@@ -215,6 +216,28 @@ end
     @test_throws HTTP.IOError HTTP.get("http://httpbin.org/delay/5"; readtimeout=1, retry=false)
 end
 
+@testset "Retry all resolved IP addresses" begin
+    # See issue https://github.com/JuliaWeb/HTTP.jl/issues/672
+    # Bit tricky to test, but can at least be tested if localhost
+    # resolves to both IPv4 and IPv6 by listening to the respective
+    # interface
+    alladdrs = getalladdrinfo("localhost")
+    if ip"127.0.0.1" in alladdrs && ip"::1" in alladdrs
+        for interface in (IPv4(0), IPv6(0))
+            server = listen(interface, 8080)
+            @async HTTP.listen(string(interface), 8080; server=server) do http
+                HTTP.setstatus(http, 200)
+                HTTP.startwrite(http)
+                HTTP.write(http, "hello, world")
+            end
+            req = HTTP.get("http://localhost:8080")
+            close(server)
+            @test req.status == 200
+            @test String(req.body) == "hello, world"
+        end
+    end
+end
+
 @testset "Public entry point of HTTP.request and friends (e.g. issue #463)" begin
     headers = Dict("User-Agent" => "HTTP.jl")
     query = Dict("hello" => "world")