wireproto: define and implement HTTP handshake to upgrade protocol
When clients connect to repositories over HTTP, they issue a request
to the well-known URL "?cmd=capabilities" to fetch the repository
capabilities. This is the handshake portion of the HTTP protocol.
This commit defines a mechanism to use that HTTP request to return
information about modern server features.
If a client sends an X-HgUpgrade-* header containing a list of
client-supported API names, the server responds with a response
containing information about available services. This includes
the normal capabilities string. So if the server doesn't support
any newer services, the client can easily fall back.
By advertising supported services from clients, server operators
can see and log what client support exists in the wild. This will
also help with debugging.
The response contains the base path to API services. We know there
are potential issues with the <repo>/api/ URL space conflicting with
hgwebdir and subrepos. By making the API URL dynamic from the
perspective of the client, the URL for APIs is not subject to backwards
compatibility concerns - at least as long as a ?cmd=capabilities request
is made.
We've also defined the ``cbor`` client capability for the X-HgProto-*
header. This MUST be sent in order to get the modern response from
"?cmd=capabilities". During implementation, I initially always sent
an application/mercurial-cbor response. However, the handshake
mechanism will be more future compatible if the client is in charge
of which formats to request. We already perform content negotiation
from X-HgProto-*, so keying off this for the capabilities response
feels appropriate.
In addition, I initially used application/cbor. However, it is
conceivable that a non-Mercurial server could serve application/cbor.
To rule out this possibility, I've invented a new media type that
is Mercurial specific and can't be confused for generic CBOR.
Differential Revision: https://phab.mercurial-scm.org/D3242
$ hg init a
$ cd a
$ cp "$TESTDIR/binfile.bin" .
$ hg add binfile.bin
$ hg ci -m 'add binfile.bin'
$ echo >> binfile.bin
$ hg ci -m 'change binfile.bin'
$ hg revert -r 0 binfile.bin
$ hg ci -m 'revert binfile.bin'
$ hg cp binfile.bin nonbinfile
$ echo text > nonbinfile
$ hg ci -m 'make non-binary copy of binary file'
$ hg diff --nodates -r 0 -r 1
diff -r 48b371597640 -r acea2ab458c8 binfile.bin
Binary file binfile.bin has changed
$ hg diff --nodates -r 0 -r 2
$ hg diff --git -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..58dc31a9e2f40f74ff3b45903f7d620b8e5b7356
GIT binary patch
literal 594
zc$@)J0<HatP)<h;3K|Lk000e1NJLTq000mG000mO0ssI2kdbIM00009a7bBm000XU
z000XU0RWnu7ytkO2XskIMF-Uh9TW;VpMjwv0005-Nkl<ZD9@FWPs=e;7{<>W$NUkd
zX$nnYLt$-$V!?uy+1V%`z&Eh=ah|duER<4|QWhju3gb^nF*8iYobxWG-qqXl=2~5M
z*IoDB)sG^CfNuoBmqLTVU^<;@nwHP!1wrWd`{(mHo6VNXWtyh{alzqmsH*yYzpvLT
zLdY<T=ks|woh-`&01!ej#(xbV1f|pI*=%;d-%F*E*X#ZH`4I%6SS+$EJDE&ct=8po
ziN#{?_j|kD%Cd|oiqds`xm@;oJ-^?NG3Gdqrs?5u*zI;{nogxsx~^|Fn^Y?Gdc6<;
zfMJ+iF1J`LMx&A2?dEwNW8ClebzPTbIh{@$hS6*`kH@1d%Lo7fA#}N1)oN7`gm$~V
z+wDx#)OFqMcE{s!JN0-xhG8ItAjVkJwEcb`3WWlJfU2r?;Pd%dmR+q@mSri5q9_W-
zaR2~ECX?B2w+zELozC0s*6Z~|QG^f{3I#<`?)Q7U-JZ|q5W;9Q8i_=pBuSzunx=U;
z9C)5jBoYw9^?EHyQl(M}1OlQcCX>lXB*ODN003Z&P17_@)3Pi=i0wb04<W?v-u}7K
zXmmQA+wDgE!qR9o8jr`%=ab_&uh(l?R=r;Tjiqon91I2-hIu?57~@*4h7h9uORK#=
gQItJW-{SoTm)8|5##k|m00000NkvXXu0mjf3JwksH2?qr
$ hg diff --git -r 0 -r 2
$ hg diff --config diff.nobinary=True --git -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
Binary file binfile.bin has changed
$ HGPLAIN=1 hg diff --config diff.nobinary=True --git -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..58dc31a9e2f40f74ff3b45903f7d620b8e5b7356
GIT binary patch
literal 594
zc$@)J0<HatP)<h;3K|Lk000e1NJLTq000mG000mO0ssI2kdbIM00009a7bBm000XU
z000XU0RWnu7ytkO2XskIMF-Uh9TW;VpMjwv0005-Nkl<ZD9@FWPs=e;7{<>W$NUkd
zX$nnYLt$-$V!?uy+1V%`z&Eh=ah|duER<4|QWhju3gb^nF*8iYobxWG-qqXl=2~5M
z*IoDB)sG^CfNuoBmqLTVU^<;@nwHP!1wrWd`{(mHo6VNXWtyh{alzqmsH*yYzpvLT
zLdY<T=ks|woh-`&01!ej#(xbV1f|pI*=%;d-%F*E*X#ZH`4I%6SS+$EJDE&ct=8po
ziN#{?_j|kD%Cd|oiqds`xm@;oJ-^?NG3Gdqrs?5u*zI;{nogxsx~^|Fn^Y?Gdc6<;
zfMJ+iF1J`LMx&A2?dEwNW8ClebzPTbIh{@$hS6*`kH@1d%Lo7fA#}N1)oN7`gm$~V
z+wDx#)OFqMcE{s!JN0-xhG8ItAjVkJwEcb`3WWlJfU2r?;Pd%dmR+q@mSri5q9_W-
zaR2~ECX?B2w+zELozC0s*6Z~|QG^f{3I#<`?)Q7U-JZ|q5W;9Q8i_=pBuSzunx=U;
z9C)5jBoYw9^?EHyQl(M}1OlQcCX>lXB*ODN003Z&P17_@)3Pi=i0wb04<W?v-u}7K
zXmmQA+wDgE!qR9o8jr`%=ab_&uh(l?R=r;Tjiqon91I2-hIu?57~@*4h7h9uORK#=
gQItJW-{SoTm)8|5##k|m00000NkvXXu0mjf3JwksH2?qr
$ hg diff --git -r 2 -r 3
diff --git a/binfile.bin b/nonbinfile
copy from binfile.bin
copy to nonbinfile
index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..8e27be7d6154a1f68ea9160ef0e18691d20560dc
GIT binary patch
literal 5
Mc$_OqttjCF00uV!&;S4c
$ cd ..
Test text mode with extended git-style diff format
$ hg init b
$ cd b
$ cat > writebin.py <<EOF
> import sys
> path = sys.argv[1]
> open(path, 'wb').write(b'\x00\x01\x02\x03')
> EOF
$ $PYTHON writebin.py binfile.bin
$ hg add binfile.bin
$ hg ci -m 'add binfile.bin'
$ echo >> binfile.bin
$ hg ci -m 'change binfile.bin'
$ hg diff --git -a -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
--- a/binfile.bin
+++ b/binfile.bin
@@ -1,1 +1,1 @@
-\x00\x01\x02\x03 (esc)
\ No newline at end of file
+\x00\x01\x02\x03 (esc)
$ HGPLAIN=1 hg diff --git -a -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
--- a/binfile.bin
+++ b/binfile.bin
@@ -1,1 +1,1 @@
-\x00\x01\x02\x03 (esc)
\ No newline at end of file
+\x00\x01\x02\x03 (esc)
Test binary mode with extended git-style diff format
$ hg diff --no-binary -r 0 -r 1
diff -r fb45f71337ad -r 9ca112d1a3c1 binfile.bin
Binary file binfile.bin has changed
$ hg diff --git --no-binary -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
Binary file binfile.bin has changed
$ hg diff --git --binary -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
index eaf36c1daccfdf325514461cd1a2ffbc139b5464..ba71a782e93f3fb63a428383706065e3ec2828e9
GIT binary patch
literal 5
Mc${NkWMbw50018V5dZ)H
$ hg diff --git --binary --config diff.nobinary=True -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
index eaf36c1daccfdf325514461cd1a2ffbc139b5464..ba71a782e93f3fb63a428383706065e3ec2828e9
GIT binary patch
literal 5
Mc${NkWMbw50018V5dZ)H
$ hg diff --git --binary --text -r 0 -r 1
diff --git a/binfile.bin b/binfile.bin
--- a/binfile.bin
+++ b/binfile.bin
@@ -1,1 +1,1 @@
-\x00\x01\x02\x03 (esc)
\ No newline at end of file
+\x00\x01\x02\x03 (esc)
$ cd ..