go.mod

@@ -1,8 +1,8 @@
 module src.lwithers.me.uk/go/htpack
 
 require (
-	github.com/gogo/protobuf v1.3.2
+	github.com/gogo/protobuf v1.2.1
-	golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e
+	golang.org/x/sys v0.0.0-20200113162924-86b910548bc1
 )
 
 go 1.13

go.sum

@@ -1,33 +1,7 @@
-github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
+github.com/gogo/protobuf v1.2.1 h1:/s5zKNz0uPFCZ5hddgPdo2TK2TVrUNMn0OOX8/aZMTE=
-github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
+github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
-github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
+github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
-github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/sys v0.0.0-20200113162924-86b910548bc1 h1:gZpLHxUX5BdYLA08Lj4YCJNN/jk7KtquiArPoeX0WvA=
-github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/sys v0.0.0-20200113162924-86b910548bc1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/tools v0.0.0-20180221164845-07fd8470d635/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e h1:CsOuNlbOuf0mzxJIefr6Q4uAUetRUwZE4qt7VfzP+xo=
-golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
-golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

handler.go

@@ -2,12 +2,14 @@ package htpack
 
 import (
 	"fmt"
+	"net"
 	"net/http"
 	"os"
 	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 
 	"golang.org/x/sys/unix"
@@ -19,13 +21,14 @@ const (
 	encodingBrotli = "br"
 )
 
+// TODO: logging
+
 // New returns a new handler. Standard security headers are set.
 func New(packfile string) (*Handler, error) {
 	f, err := os.Open(packfile)
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
 
 	fi, err := f.Stat()
 	if err != nil {
@@ -34,16 +37,19 @@ func New(packfile string) (*Handler, error) {
 	mapped, err := unix.Mmap(int(f.Fd()), 0, int(fi.Size()),
 		unix.PROT_READ, unix.MAP_SHARED)
 	if err != nil {
+		f.Close()
 		return nil, err
 	}
 
 	_, dir, err := packed.Load(f)
 	if err != nil {
 		unix.Munmap(mapped)
+		f.Close()
 		return nil, err
 	}
 
 	h := &Handler{
+		f:         f,
 		mapped:    mapped,
 		dir:       dir.Files,
 		headers:   make(map[string]string),
@@ -61,6 +67,7 @@ func New(packfile string) (*Handler, error) {
 
 // Handler implements http.Handler and allows options to be set.
 type Handler struct {
+	f         *os.File
 	mapped    []byte
 	dir       map[string]*packed.File
 	headers   map[string]string
@@ -196,7 +203,87 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	if req.Method == "HEAD" {
 		return
 	}
+	h.sendfile(w, data, offset, length)
+}
 
+func (h *Handler) sendfile(w http.ResponseWriter, data *packed.FileData,
+	offset, length uint64,
+) {
+	hj, ok := w.(http.Hijacker)
+	if !ok {
+		// fallback
+		h.copyfile(w, data, offset, length)
+		return
+	}
+
+	conn, buf, err := hj.Hijack()
+	if err != nil {
+		// fallback
+		h.copyfile(w, data, offset, length)
+		return
+	}
+
+	tcp, ok := conn.(*net.TCPConn)
+	if !ok {
+		// fallback
+		h.copyfile(w, data, offset, length)
+		return
+	}
+	defer tcp.Close()
+
+	rawsock, err := tcp.SyscallConn()
+	if err == nil {
+		err = buf.Flush()
+	}
+	if err != nil {
+		// error only returned if the underlying connection is broken,
+		// so there's no point calling sendfile
+		return
+	}
+
+	var breakErr error
+	off := int64(data.Offset + offset)
+	remain := length
+
+	for breakErr == nil && remain > 0 {
+		// sendfile(2) can send a maximum of 1GiB
+		var amt int
+		if remain > (1 << 30) {
+			amt = (1 << 30)
+		} else {
+			amt = int(remain)
+		}
+
+		// behaviour of control function:
+		//  · some bytes written: sets written > 0, returns true (breaks
+		//                        out of loop on first write)
+		//  · EAGAIN: returns false (causes Write() to loop until
+		//            success or permanent failure)
+		//  · other error: sets breakErr
+		var written int
+		rawsock.Write(func(outfd uintptr) bool {
+			written, err = unix.Sendfile(int(outfd), int(h.f.Fd()), &off, amt)
+			switch err {
+			case nil:
+				return true
+			case syscall.EAGAIN:
+				return false
+			default:
+				breakErr = err
+				return true
+			}
+		})
+
+		// we may have had a partial write, or file may have been > 1GiB
+		remain -= uint64(written)
+	}
+}
+
+// copyfile is a fallback handler that uses write(2) on our memory-mapped data
+// to push out the response.
+func (h *Handler) copyfile(w http.ResponseWriter, data *packed.FileData,
+	offset, length uint64,
+) {
 	offset += data.Offset
 	w.Write(h.mapped[offset : offset+length])
 }