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