generic: net return full response struct

This is still quite easy to stub, and the extra information is very
useful to the caller.

Signed-off-by: Yonah <contrib@gensokyo.uk>

cmd/msrfetch/fetch.go

@@ -8,6 +8,7 @@ import (
 	"flag"
 	"io"
 	"log"
+	"net/http"
 	"os"
 	"path"
 	"slices"
@@ -97,19 +98,21 @@ func mustFetch(ctx context.Context) {
 			defer wg.Done()
 			for u := range uc {
 				buf := new(bytes.Buffer)
-				if r, l, err := n.Get(ctx, u); err != nil {
+				if resp, err := n.Get(ctx, u); err != nil {
 					log.Fatal(err)
+				} else if resp.StatusCode != http.StatusOK {
+					log.Fatal(&monstersirenfetch.ResponseStatusError{URL: u, StatusCode: resp.StatusCode, CloseErr: resp.Body.Close()})
 				} else {
-					if v := int(l); v > 0 {
+					if v := int(resp.ContentLength); v > 0 {
 						buf.Grow(v)
 					}
-					if _, err = io.Copy(buf, r); err != nil {
-						if closeErr := r.Close(); closeErr != nil {
+					if _, err = io.Copy(buf, resp.Body); err != nil {
+						if closeErr := resp.Body.Close(); closeErr != nil {
 							log.Print(closeErr)
 						}
 						log.Fatal(err)
 					}
-					if err = r.Close(); err != nil {
+					if err = resp.Body.Close(); err != nil {
 						log.Fatal(err)
 					}
 				}

cmd/msrfetch/net.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"io"
 	"net/http"
 )
 
@@ -10,12 +9,12 @@ type netDirect struct {
 	c http.Client
 }
 
-func (n *netDirect) Get(ctx context.Context, url string) (io.ReadCloser, int64, error) {
+func (n *netDirect) Get(ctx context.Context, url string) (*http.Response, error) {
 	var resp *http.Response
 	if req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil); err != nil {
-		return nil, -2, err
+		return nil, err
 	} else if resp, err = n.c.Do(req); err != nil {
-		return nil, -2, err
+		return nil, err
 	}
-	return resp.Body, resp.ContentLength, nil
+	return resp, nil
 }