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 "protocol-caps.h"
   9 #include "serve.h"
  10 #include "upload-pack.h"
  11
  12 static int advertise_sid = -1;
  13 static int client_hash_algo = GIT_HASH_SHA1;
  14
  15 static int always_advertise(struct repository *r,
  16                             struct strbuf *value)
  17 {
  18         return 1;
  19 }
  20
  21 static int agent_advertise(struct repository *r,
  22                            struct strbuf *value)
  23 {
  24         if (value)
  25                 strbuf_addstr(value, git_user_agent_sanitized());
  26         return 1;
  27 }
  28
  29 static int object_format_advertise(struct repository *r,
  30                                    struct strbuf *value)
  31 {
  32         if (value)
  33                 strbuf_addstr(value, r->hash_algo->name);
  34         return 1;
  35 }
  36
  37 static void object_format_receive(struct repository *r,
  38                                   const char *algo_name)
  39 {
  40         if (!algo_name)
  41                 die("object-format capability requires an argument");
  42
  43         client_hash_algo = hash_algo_by_name(algo_name);
  44         if (client_hash_algo == GIT_HASH_UNKNOWN)
  45                 die("unknown object format '%s'", algo_name);
  46 }
  47
  48 static int session_id_advertise(struct repository *r, struct strbuf *value)
  49 {
  50         if (advertise_sid == -1 &&
  51             git_config_get_bool("transfer.advertisesid", &advertise_sid))
  52                 advertise_sid = 0;
  53         if (!advertise_sid)
  54                 return 0;
  55         if (value)
  56                 strbuf_addstr(value, trace2_session_id());
  57         return 1;
  58 }
  59
  60 static void session_id_receive(struct repository *r,
  61                                const char *client_sid)
  62 {
  63         if (!client_sid)
  64                 client_sid = "";
  65         trace2_data_string("transfer", NULL, "client-sid", client_sid);
  66 }
  67
  68 struct protocol_capability {
  69         /*
  70          * The name of the capability.  The server uses this name when
  71          * advertising this capability, and the client uses this name to
  72          * specify this capability.
  73          */
  74         const char *name;
  75
  76         /*
  77          * Function queried to see if a capability should be advertised.
  78          * Optionally a value can be specified by adding it to 'value'.
  79          * If a value is added to 'value', the server will advertise this
  80          * capability as "<name>=<value>" instead of "<name>".
  81          */
  82         int (*advertise)(struct repository *r, struct strbuf *value);
  83
  84         /*
  85          * Function called when a client requests the capability as a command.
  86          * Will be provided a struct packet_reader 'request' which it should
  87          * use to read the command specific part of the request.  Every command
  88          * MUST read until a flush packet is seen before sending a response.
  89          *
  90          * This field should be NULL for capabilities which are not commands.
  91          */
  92         int (*command)(struct repository *r, struct packet_reader *request);
  93
  94         /*
  95          * Function called when a client requests the capability as a
  96          * non-command. This may be NULL if the capability does nothing.
  97          *
  98          * For a capability of the form "foo=bar", the value string points to
  99          * the content after the "=" (i.e., "bar"). For simple capabilities
 100          * (just "foo"), it is NULL.
 101          */
 102         void (*receive)(struct repository *r, const char *value);
 103 };
 104
 105 static struct protocol_capability capabilities[] = {
 106         {
 107                 .name = "agent",
 108                 .advertise = agent_advertise,
 109         },
 110         {
 111                 .name = "ls-refs",
 112                 .advertise = ls_refs_advertise,
 113                 .command = ls_refs,
 114         },
 115         {
 116                 .name = "fetch",
 117                 .advertise = upload_pack_advertise,
 118                 .command = upload_pack_v2,
 119         },
 120         {
 121                 .name = "server-option",
 122                 .advertise = always_advertise,
 123         },
 124         {
 125                 .name = "object-format",
 126                 .advertise = object_format_advertise,
 127                 .receive = object_format_receive,
 128         },
 129         {
 130                 .name = "session-id",
 131                 .advertise = session_id_advertise,
 132                 .receive = session_id_receive,
 133         },
 134         {
 135                 .name = "object-info",
 136                 .advertise = always_advertise,
 137                 .command = cap_object_info,
 138         },
 139 };
 140
 141 void protocol_v2_advertise_capabilities(void)
 142 {
 143         struct strbuf capability = STRBUF_INIT;
 144         struct strbuf value = STRBUF_INIT;
 145         int i;
 146
 147         /* serve by default supports v2 */
 148         packet_write_fmt(1, "version 2\n");
 149
 150         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
 151                 struct protocol_capability *c = &capabilities[i];
 152
 153                 if (c->advertise(the_repository, &value)) {
 154                         strbuf_addstr(&capability, c->name);
 155
 156                         if (value.len) {
 157                                 strbuf_addch(&capability, '=');
 158                                 strbuf_addbuf(&capability, &value);
 159                         }
 160
 161                         strbuf_addch(&capability, '\n');
 162                         packet_write(1, capability.buf, capability.len);
 163                 }
 164
 165                 strbuf_reset(&capability);
 166                 strbuf_reset(&value);
 167         }
 168
 169         packet_flush(1);
 170         strbuf_release(&capability);
 171         strbuf_release(&value);
 172 }
 173
 174 static struct protocol_capability *get_capability(const char *key, const char **value)
 175 {
 176         int i;
 177
 178         if (!key)
 179                 return NULL;
 180
 181         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
 182                 struct protocol_capability *c = &capabilities[i];
 183                 const char *out;
 184                 if (!skip_prefix(key, c->name, &out))
 185                         continue;
 186                 if (!*out) {
 187                         *value = NULL;
 188                         return c;
 189                 }
 190                 if (*out++ == '=') {
 191                         *value = out;
 192                         return c;
 193                 }
 194         }
 195
 196         return NULL;
 197 }
 198
 199 static int receive_client_capability(const char *key)
 200 {
 201         const char *value;
 202         const struct protocol_capability *c = get_capability(key, &value);
 203
 204         if (!c || c->command || !c->advertise(the_repository, NULL))
 205                 return 0;
 206
 207         if (c->receive)
 208                 c->receive(the_repository, value);
 209         return 1;
 210 }
 211
 212 static int parse_command(const char *key, struct protocol_capability **command)
 213 {
 214         const char *out;
 215
 216         if (skip_prefix(key, "command=", &out)) {
 217                 const char *value;
 218                 struct protocol_capability *cmd = get_capability(out, &value);
 219
 220                 if (*command)
 221                         die("command '%s' requested after already requesting command '%s'",
 222                             out, (*command)->name);
 223                 if (!cmd || !cmd->advertise(the_repository, NULL) || !cmd->command || value)
 224                         die("invalid command '%s'", out);
 225
 226                 *command = cmd;
 227                 return 1;
 228         }
 229
 230         return 0;
 231 }
 232
 233 enum request_state {
 234         PROCESS_REQUEST_KEYS,
 235         PROCESS_REQUEST_DONE,
 236 };
 237
 238 static int process_request(void)
 239 {
 240         enum request_state state = PROCESS_REQUEST_KEYS;
 241         struct packet_reader reader;
 242         int seen_capability_or_command = 0;
 243         struct protocol_capability *command = NULL;
 244
 245         packet_reader_init(&reader, 0, NULL, 0,
 246                            PACKET_READ_CHOMP_NEWLINE |
 247                            PACKET_READ_GENTLE_ON_EOF |
 248                            PACKET_READ_DIE_ON_ERR_PACKET);
 249
 250         /*
 251          * Check to see if the client closed their end before sending another
 252          * request.  If so we can terminate the connection.
 253          */
 254         if (packet_reader_peek(&reader) == PACKET_READ_EOF)
 255                 return 1;
 256         reader.options &= ~PACKET_READ_GENTLE_ON_EOF;
 257
 258         while (state != PROCESS_REQUEST_DONE) {
 259                 switch (packet_reader_peek(&reader)) {
 260                 case PACKET_READ_EOF:
 261                         BUG("Should have already died when seeing EOF");
 262                 case PACKET_READ_NORMAL:
 263                         if (parse_command(reader.line, &command) ||
 264                             receive_client_capability(reader.line))
 265                                 seen_capability_or_command = 1;
 266                         else
 267                                 die("unknown capability '%s'", reader.line);
 268
 269                         /* Consume the peeked line */
 270                         packet_reader_read(&reader);
 271                         break;
 272                 case PACKET_READ_FLUSH:
 273                         /*
 274                          * If no command and no keys were given then the client
 275                          * wanted to terminate the connection.
 276                          */
 277                         if (!seen_capability_or_command)
 278                                 return 1;
 279
 280                         /*
 281                          * The flush packet isn't consume here like it is in
 282                          * the other parts of this switch statement.  This is
 283                          * so that the command can read the flush packet and
 284                          * see the end of the request in the same way it would
 285                          * if command specific arguments were provided after a
 286                          * delim packet.
 287                          */
 288                         state = PROCESS_REQUEST_DONE;
 289                         break;
 290                 case PACKET_READ_DELIM:
 291                         /* Consume the peeked line */
 292                         packet_reader_read(&reader);
 293
 294                         state = PROCESS_REQUEST_DONE;
 295                         break;
 296                 case PACKET_READ_RESPONSE_END:
 297                         BUG("unexpected response end packet");
 298                 }
 299         }
 300
 301         if (!command)
 302                 die("no command requested");
 303
 304         if (client_hash_algo != hash_algo_by_ptr(the_repository->hash_algo))
 305                 die("mismatched object format: server %s; client %s\n",
 306                     the_repository->hash_algo->name,
 307                     hash_algos[client_hash_algo].name);
 308
 309         command->command(the_repository, &reader);
 310
 311         return 0;
 312 }
 313
 314 void protocol_v2_serve_loop(int stateless_rpc)
 315 {
 316         if (!stateless_rpc)
 317                 protocol_v2_advertise_capabilities();
 318
 319         /*
 320          * If stateless-rpc was requested then exit after
 321          * a single request/response exchange
 322          */
 323         if (stateless_rpc) {
 324                 process_request();
 325         } else {
 326                 for (;;)
 327                         if (process_request())
 328                                 break;
 329         }
 330 }