The following command hangs forever: $ git -c protocol.version=2 clone https://github.com/git/git.git --shallow-since=20151012 Cloning into 'git'... This occurs because the --shallow-since arg is incorrect and the server dies early. However, remote-curl does not realise that the server errored out and just faithfully forwards the packets to fetch-pack before waiting on more input from fetch-pack. Meanwhile, fetch-pack keeps reading as it still expects more input. As a result, the processes deadlock. Original analysis by Peff: https://lore.kernel.org/git/20200328154936.GA1217052@xxxxxxxxxxxxxxxxxxxxxxx/ Changes since v1: * Remove fallthrough in switch in favour of just extracting the common call out of the switch in patch 3 * Add more detail in function comment and use `const char linelen[4]` in patch 4 * Implement most of Peff's suggestions[0] in patch 5 * Only operate on stateless_connect() in patch 5 * Add tests in patch 5 * Drop "remote-curl: ensure last packet is a flush" in favour of "stateless-connect: send response end packet" [0]: https://lore.kernel.org/git/20200515213844.GD115445@xxxxxxxxxxxxxxxxxxxxxxx/ Denton Liu (7): remote-curl: fix typo remote-curl: remove label indentation transport: extract common fetch_pack() call pkt-line: extern packet_length() remote-curl: error on incomplete packet pkt-line: PACKET_READ_RESPONSE_END stateless-connect: send response end packet Documentation/gitremote-helpers.txt | 4 +- Documentation/technical/protocol-v2.txt | 2 + builtin/fetch-pack.c | 2 +- connect.c | 12 +++- fetch-pack.c | 12 ++++ pkt-line.c | 13 +++- pkt-line.h | 11 +++ remote-curl.c | 72 +++++++++++++++++-- remote.h | 3 +- serve.c | 2 + t/helper/test-pkt-line.c | 4 ++ t/lib-httpd.sh | 2 + t/lib-httpd/apache.conf | 8 +++ .../incomplete-body-upload-pack-v2-http.sh | 3 + .../incomplete-length-upload-pack-v2-http.sh | 3 + t/t5702-protocol-v2.sh | 47 ++++++++++++ transport.c | 16 ++--- 17 files changed, 197 insertions(+), 19 deletions(-) create mode 100644 t/lib-httpd/incomplete-body-upload-pack-v2-http.sh create mode 100644 t/lib-httpd/incomplete-length-upload-pack-v2-http.sh Range-diff against v1: 1: b390875f87 = 1: b390875f87 remote-curl: fix typo 2: a2b28c0b28 = 2: a2b28c0b28 remote-curl: remove label indentation 3: c89c184100 < -: ---------- transport: combine common cases with a fallthrough -: ---------- > 3: 3a42575bd5 transport: extract common fetch_pack() call 4: 891a39c853 ! 4: c2b9d033bb pkt-line: extern packet_length() @@ Commit message need to access the length header. In order to simplify this, extern packet_length() so that the logic can be reused. + Change the function parameter from a `const char *` to + `const char linelen[4]`. Even though these two types behave identically + as function parameters, use the array notation to semantically indicate + exactly what this function is expecting as an argument. + ## pkt-line.c ## @@ pkt-line.c: static int get_packet_data(int fd, char **src_buf, size_t *src_size, return ret; } -static int packet_length(const char *linelen) -+int packet_length(const char *linelen) ++int packet_length(const char linelen[4]) { int val = hex2chr(linelen); return (val < 0) ? val : (val << 8) | hex2chr(linelen + 2); @@ pkt-line.h: int write_packetized_from_buf(const char *src_in, size_t len, int fd *buffer, unsigned size, int options); +/* -+ * Reads a packetized line and returns the length header of the packet. ++ * Convert a four hex digit packet line length header into its numeric ++ * representation. linelen should not be null-terminated. ++ * ++ * If linelen contains non-hex characters, return -1. Otherwise, return the ++ * numeric value of the length header. + */ -+int packet_length(const char *linelen); ++int packet_length(const char linelen[4]); + /* * Read a packetized line into a buffer like the 'packet_read()' function but 5: 3ed7cf87aa < -: ---------- remote-curl: error on incomplete packet 6: 7a689da2bb < -: ---------- remote-curl: ensure last packet is a flush -: ---------- > 5: 52ce5fdffd remote-curl: error on incomplete packet -: ---------- > 6: 744b078324 pkt-line: PACKET_READ_RESPONSE_END -: ---------- > 7: 4b079bcd83 stateless-connect: send response end packet -- 2.26.2.706.g87896c9627
