serve.c

   1 #include "cache.h"
   2 #include "repository.h"
   3 #include "config.h"
   4 #include "pkt-line.h"
   5 #include "version.h"
   6 #include "strvec.h"
   7 #include "ls-refs.h"
   8 #include "serve.h"
   9 #include "upload-pack.h"
  10
  11 static int always_advertise(struct repository *r,
  12                             struct strbuf *value)
  13 {
  14         return 1;
  15 }
  16
  17 static int agent_advertise(struct repository *r,
  18                            struct strbuf *value)
  19 {
  20         if (value)
  21                 strbuf_addstr(value, git_user_agent_sanitized());
  22         return 1;
  23 }
  24
  25 static int object_format_advertise(struct repository *r,
  26                                    struct strbuf *value)
  27 {
  28         if (value)
  29                 strbuf_addstr(value, r->hash_algo->name);
  30         return 1;
  31 }
  32
  33 struct protocol_capability {
  34         /*
  35          * The name of the capability.  The server uses this name when
  36          * advertising this capability, and the client uses this name to
  37          * specify this capability.
  38          */
  39         const char *name;
  40
  41         /*
  42          * Function queried to see if a capability should be advertised.
  43          * Optionally a value can be specified by adding it to 'value'.
  44          * If a value is added to 'value', the server will advertise this
  45          * capability as "<name>=<value>" instead of "<name>".
  46          */
  47         int (*advertise)(struct repository *r, struct strbuf *value);
  48
  49         /*
  50          * Function called when a client requests the capability as a command.
  51          * The function will be provided the capabilities requested via 'keys'
  52          * as well as a struct packet_reader 'request' which the command should
  53          * use to read the command specific part of the request.  Every command
  54          * MUST read until a flush packet is seen before sending a response.
  55          *
  56          * This field should be NULL for capabilities which are not commands.
  57          */
  58         int (*command)(struct repository *r,
  59                        struct strvec *keys,
  60                        struct packet_reader *request);
  61 };
  62
  63 static struct protocol_capability capabilities[] = {
  64         { "agent", agent_advertise, NULL },
  65         { "ls-refs", always_advertise, ls_refs },
  66         { "fetch", upload_pack_advertise, upload_pack_v2 },
  67         { "server-option", always_advertise, NULL },
  68         { "object-format", object_format_advertise, NULL },
  69 };
  70
  71 static void advertise_capabilities(void)
  72 {
  73         struct strbuf capability = STRBUF_INIT;
  74         struct strbuf value = STRBUF_INIT;
  75         int i;
  76
  77         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
  78                 struct protocol_capability *c = &capabilities[i];
  79
  80                 if (c->advertise(the_repository, &value)) {
  81                         strbuf_addstr(&capability, c->name);
  82
  83                         if (value.len) {
  84                                 strbuf_addch(&capability, '=');
  85                                 strbuf_addbuf(&capability, &value);
  86                         }
  87
  88                         strbuf_addch(&capability, '\n');
  89                         packet_write(1, capability.buf, capability.len);
  90                 }
  91
  92                 strbuf_reset(&capability);
  93                 strbuf_reset(&value);
  94         }
  95
  96         packet_flush(1);
  97         strbuf_release(&capability);
  98         strbuf_release(&value);
  99 }
 100
 101 static struct protocol_capability *get_capability(const char *key)
 102 {
 103         int i;
 104
 105         if (!key)
 106                 return NULL;
 107
 108         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
 109                 struct protocol_capability *c = &capabilities[i];
 110                 const char *out;
 111                 if (skip_prefix(key, c->name, &out) && (!*out || *out == '='))
 112                         return c;
 113         }
 114
 115         return NULL;
 116 }
 117
 118 static int is_valid_capability(const char *key)
 119 {
 120         const struct protocol_capability *c = get_capability(key);
 121
 122         return c && c->advertise(the_repository, NULL);
 123 }
 124
 125 static int is_command(const char *key, struct protocol_capability **command)
 126 {
 127         const char *out;
 128
 129         if (skip_prefix(key, "command=", &out)) {
 130                 struct protocol_capability *cmd = get_capability(out);
 131
 132                 if (*command)
 133                         die("command '%s' requested after already requesting command '%s'",
 134                             out, (*command)->name);
 135                 if (!cmd || !cmd->advertise(the_repository, NULL) || !cmd->command)
 136                         die("invalid command '%s'", out);
 137
 138                 *command = cmd;
 139                 return 1;
 140         }
 141
 142         return 0;
 143 }
 144
 145 int has_capability(const struct strvec *keys, const char *capability,
 146                    const char **value)
 147 {
 148         int i;
 149         for (i = 0; i < keys->nr; i++) {
 150                 const char *out;
 151                 if (skip_prefix(keys->v[i], capability, &out) &&
 152                     (!*out || *out == '=')) {
 153                         if (value) {
 154                                 if (*out == '=')
 155                                         out++;
 156                                 *value = out;
 157                         }
 158                         return 1;
 159                 }
 160         }
 161
 162         return 0;
 163 }
 164
 165 static void check_algorithm(struct repository *r, struct strvec *keys)
 166 {
 167         int client = GIT_HASH_SHA1, server = hash_algo_by_ptr(r->hash_algo);
 168         const char *algo_name;
 169
 170         if (has_capability(keys, "object-format", &algo_name)) {
 171                 client = hash_algo_by_name(algo_name);
 172                 if (client == GIT_HASH_UNKNOWN)
 173                         die("unknown object format '%s'", algo_name);
 174         }
 175
 176         if (client != server)
 177                 die("mismatched object format: server %s; client %s\n",
 178                     r->hash_algo->name, hash_algos[client].name);
 179 }
 180
 181 enum request_state {
 182         PROCESS_REQUEST_KEYS,
 183         PROCESS_REQUEST_DONE,
 184 };
 185
 186 static int process_request(void)
 187 {
 188         enum request_state state = PROCESS_REQUEST_KEYS;
 189         struct packet_reader reader;
 190         struct strvec keys = STRVEC_INIT;
 191         struct protocol_capability *command = NULL;
 192
 193         packet_reader_init(&reader, 0, NULL, 0,
 194                            PACKET_READ_CHOMP_NEWLINE |
 195                            PACKET_READ_GENTLE_ON_EOF |
 196                            PACKET_READ_DIE_ON_ERR_PACKET);
 197
 198         /*
 199          * Check to see if the client closed their end before sending another
 200          * request.  If so we can terminate the connection.
 201          */
 202         if (packet_reader_peek(&reader) == PACKET_READ_EOF)
 203                 return 1;
 204         reader.options &= ~PACKET_READ_GENTLE_ON_EOF;
 205
 206         while (state != PROCESS_REQUEST_DONE) {
 207                 switch (packet_reader_peek(&reader)) {
 208                 case PACKET_READ_EOF:
 209                         BUG("Should have already died when seeing EOF");
 210                 case PACKET_READ_NORMAL:
 211                         /* collect request; a sequence of keys and values */
 212                         if (is_command(reader.line, &command) ||
 213                             is_valid_capability(reader.line))
 214                                 strvec_push(&keys, reader.line);
 215                         else
 216                                 die("unknown capability '%s'", reader.line);
 217
 218                         /* Consume the peeked line */
 219                         packet_reader_read(&reader);
 220                         break;
 221                 case PACKET_READ_FLUSH:
 222                         /*
 223                          * If no command and no keys were given then the client
 224                          * wanted to terminate the connection.
 225                          */
 226                         if (!keys.nr)
 227                                 return 1;
 228
 229                         /*
 230                          * The flush packet isn't consume here like it is in
 231                          * the other parts of this switch statement.  This is
 232                          * so that the command can read the flush packet and
 233                          * see the end of the request in the same way it would
 234                          * if command specific arguments were provided after a
 235                          * delim packet.
 236                          */
 237                         state = PROCESS_REQUEST_DONE;
 238                         break;
 239                 case PACKET_READ_DELIM:
 240                         /* Consume the peeked line */
 241                         packet_reader_read(&reader);
 242
 243                         state = PROCESS_REQUEST_DONE;
 244                         break;
 245                 case PACKET_READ_RESPONSE_END:
 246                         BUG("unexpected stateless separator packet");
 247                 }
 248         }
 249
 250         if (!command)
 251                 die("no command requested");
 252
 253         check_algorithm(the_repository, &keys);
 254
 255         command->command(the_repository, &keys, &reader);
 256
 257         strvec_clear(&keys);
 258         return 0;
 259 }
 260
 261 /* Main serve loop for protocol version 2 */
 262 void serve(struct serve_options *options)
 263 {
 264         if (options->advertise_capabilities || !options->stateless_rpc) {
 265                 /* serve by default supports v2 */
 266                 packet_write_fmt(1, "version 2\n");
 267
 268                 advertise_capabilities();
 269                 /*
 270                  * If only the list of capabilities was requested exit
 271                  * immediately after advertising capabilities
 272                  */
 273                 if (options->advertise_capabilities)
 274                         return;
 275         }
 276
 277         /*
 278          * If stateless-rpc was requested then exit after
 279          * a single request/response exchange
 280          */
 281         if (options->stateless_rpc) {
 282                 process_request();
 283         } else {
 284                 for (;;)
 285                         if (process_request())
 286                                 break;
 287         }
 288 }