http-backend.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "pkt-line.h"
   4 #include "object.h"
   5 #include "tag.h"
   6 #include "exec_cmd.h"
   7
   8 static const char content_type[] = "Content-Type";
   9 static const char content_length[] = "Content-Length";
  10 static const char last_modified[] = "Last-Modified";
  11
  12 static void format_write(int fd, const char *fmt, ...)
  13 {
  14         static char buffer[1024];
  15
  16         va_list args;
  17         unsigned n;
  18
  19         va_start(args, fmt);
  20         n = vsnprintf(buffer, sizeof(buffer), fmt, args);
  21         va_end(args);
  22         if (n >= sizeof(buffer))
  23                 die("protocol error: impossibly long line");
  24
  25         safe_write(fd, buffer, n);
  26 }
  27
  28 static void http_status(unsigned code, const char *msg)
  29 {
  30         format_write(1, "Status: %u %s\r\n", code, msg);
  31 }
  32
  33 static void hdr_str(const char *name, const char *value)
  34 {
  35         format_write(1, "%s: %s\r\n", name, value);
  36 }
  37
  38 static void hdr_int(const char *name, size_t value)
  39 {
  40         format_write(1, "%s: %" PRIuMAX "\r\n", name, value);
  41 }
  42
  43 static void hdr_date(const char *name, unsigned long when)
  44 {
  45         const char *value = show_date(when, 0, DATE_RFC2822);
  46         hdr_str(name, value);
  47 }
  48
  49 static void hdr_nocache(void)
  50 {
  51         hdr_str("Expires", "Fri, 01 Jan 1980 00:00:00 GMT");
  52         hdr_str("Pragma", "no-cache");
  53         hdr_str("Cache-Control", "no-cache, max-age=0, must-revalidate");
  54 }
  55
  56 static void hdr_cache_forever(void)
  57 {
  58         unsigned long now = time(NULL);
  59         hdr_date("Date", now);
  60         hdr_date("Expires", now + 31536000);
  61         hdr_str("Cache-Control", "public, max-age=31536000");
  62 }
  63
  64 static void end_headers(void)
  65 {
  66         safe_write(1, "\r\n", 2);
  67 }
  68
  69 static NORETURN void not_found(const char *err, ...)
  70 {
  71         va_list params;
  72
  73         http_status(404, "Not Found");
  74         hdr_nocache();
  75         end_headers();
  76
  77         va_start(params, err);
  78         if (err && *err)
  79                 vfprintf(stderr, err, params);
  80         va_end(params);
  81         exit(0);
  82 }
  83
  84 static void send_strbuf(const char *type, struct strbuf *buf)
  85 {
  86         hdr_int(content_length, buf->len);
  87         hdr_str(content_type, type);
  88         end_headers();
  89         safe_write(1, buf->buf, buf->len);
  90 }
  91
  92 static void send_file(const char *the_type, const char *name)
  93 {
  94         const char *p = git_path("%s", name);
  95         size_t buf_alloc = 8192;
  96         char *buf = xmalloc(buf_alloc);
  97         int fd;
  98         struct stat sb;
  99         size_t size;
 100
 101         fd = open(p, O_RDONLY);
 102         if (fd < 0)
 103                 not_found("Cannot open '%s': %s", p, strerror(errno));
 104         if (fstat(fd, &sb) < 0)
 105                 die_errno("Cannot stat '%s'", p);
 106
 107         size = xsize_t(sb.st_size);
 108
 109         hdr_int(content_length, size);
 110         hdr_str(content_type, the_type);
 111         hdr_date(last_modified, sb.st_mtime);
 112         end_headers();
 113
 114         while (size) {
 115                 ssize_t n = xread(fd, buf, buf_alloc);
 116                 if (n < 0)
 117                         die_errno("Cannot read '%s'", p);
 118                 if (!n)
 119                         break;
 120                 safe_write(1, buf, n);
 121         }
 122         close(fd);
 123         free(buf);
 124 }
 125
 126 static void get_text_file(char *name)
 127 {
 128         hdr_nocache();
 129         send_file("text/plain", name);
 130 }
 131
 132 static void get_loose_object(char *name)
 133 {
 134         hdr_cache_forever();
 135         send_file("application/x-git-loose-object", name);
 136 }
 137
 138 static void get_pack_file(char *name)
 139 {
 140         hdr_cache_forever();
 141         send_file("application/x-git-packed-objects", name);
 142 }
 143
 144 static void get_idx_file(char *name)
 145 {
 146         hdr_cache_forever();
 147         send_file("application/x-git-packed-objects-toc", name);
 148 }
 149
 150 static int show_text_ref(const char *name, const unsigned char *sha1,
 151         int flag, void *cb_data)
 152 {
 153         struct strbuf *buf = cb_data;
 154         struct object *o = parse_object(sha1);
 155         if (!o)
 156                 return 0;
 157
 158         strbuf_addf(buf, "%s\t%s\n", sha1_to_hex(sha1), name);
 159         if (o->type == OBJ_TAG) {
 160                 o = deref_tag(o, name, 0);
 161                 if (!o)
 162                         return 0;
 163                 strbuf_addf(buf, "%s\t%s^{}\n", sha1_to_hex(o->sha1), name);
 164         }
 165         return 0;
 166 }
 167
 168 static void get_info_refs(char *arg)
 169 {
 170         struct strbuf buf = STRBUF_INIT;
 171
 172         for_each_ref(show_text_ref, &buf);
 173         hdr_nocache();
 174         send_strbuf("text/plain", &buf);
 175         strbuf_release(&buf);
 176 }
 177
 178 static void get_info_packs(char *arg)
 179 {
 180         size_t objdirlen = strlen(get_object_directory());
 181         struct strbuf buf = STRBUF_INIT;
 182         struct packed_git *p;
 183         size_t cnt = 0;
 184
 185         prepare_packed_git();
 186         for (p = packed_git; p; p = p->next) {
 187                 if (p->pack_local)
 188                         cnt++;
 189         }
 190
 191         strbuf_grow(&buf, cnt * 53 + 2);
 192         for (p = packed_git; p; p = p->next) {
 193                 if (p->pack_local)
 194                         strbuf_addf(&buf, "P %s\n", p->pack_name + objdirlen + 6);
 195         }
 196         strbuf_addch(&buf, '\n');
 197
 198         hdr_nocache();
 199         send_strbuf("text/plain; charset=utf-8", &buf);
 200         strbuf_release(&buf);
 201 }
 202
 203 static NORETURN void die_webcgi(const char *err, va_list params)
 204 {
 205         char buffer[1000];
 206
 207         http_status(500, "Internal Server Error");
 208         hdr_nocache();
 209         end_headers();
 210
 211         vsnprintf(buffer, sizeof(buffer), err, params);
 212         fprintf(stderr, "fatal: %s\n", buffer);
 213         exit(0);
 214 }
 215
 216 static struct service_cmd {
 217         const char *method;
 218         const char *pattern;
 219         void (*imp)(char *);
 220 } services[] = {
 221         {"GET", "/HEAD$", get_text_file},
 222         {"GET", "/info/refs$", get_info_refs},
 223         {"GET", "/objects/info/alternates$", get_text_file},
 224         {"GET", "/objects/info/http-alternates$", get_text_file},
 225         {"GET", "/objects/info/packs$", get_info_packs},
 226         {"GET", "/objects/[0-9a-f]{2}/[0-9a-f]{38}$", get_loose_object},
 227         {"GET", "/objects/pack/pack-[0-9a-f]{40}\\.pack$", get_pack_file},
 228         {"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file}
 229 };
 230
 231 int main(int argc, char **argv)
 232 {
 233         char *method = getenv("REQUEST_METHOD");
 234         char *dir = getenv("PATH_TRANSLATED");
 235         struct service_cmd *cmd = NULL;
 236         char *cmd_arg = NULL;
 237         int i;
 238
 239         git_extract_argv0_path(argv[0]);
 240         set_die_routine(die_webcgi);
 241
 242         if (!method)
 243                 die("No REQUEST_METHOD from server");
 244         if (!strcmp(method, "HEAD"))
 245                 method = "GET";
 246         if (!dir)
 247                 die("No PATH_TRANSLATED from server");
 248
 249         for (i = 0; i < ARRAY_SIZE(services); i++) {
 250                 struct service_cmd *c = &services[i];
 251                 regex_t re;
 252                 regmatch_t out[1];
 253
 254                 if (regcomp(&re, c->pattern, REG_EXTENDED))
 255                         die("Bogus regex in service table: %s", c->pattern);
 256                 if (!regexec(&re, dir, 1, out, 0)) {
 257                         size_t n = out[0].rm_eo - out[0].rm_so;
 258
 259                         if (strcmp(method, c->method)) {
 260                                 const char *proto = getenv("SERVER_PROTOCOL");
 261                                 if (proto && !strcmp(proto, "HTTP/1.1"))
 262                                         http_status(405, "Method Not Allowed");
 263                                 else
 264                                         http_status(400, "Bad Request");
 265                                 hdr_nocache();
 266                                 end_headers();
 267                                 return 0;
 268                         }
 269
 270                         cmd = c;
 271                         cmd_arg = xmalloc(n);
 272                         strncpy(cmd_arg, dir + out[0].rm_so + 1, n);
 273                         cmd_arg[n] = '\0';
 274                         dir[out[0].rm_so] = 0;
 275                         break;
 276                 }
 277                 regfree(&re);
 278         }
 279
 280         if (!cmd)
 281                 not_found("Request not supported: '%s'", dir);
 282
 283         setup_path();
 284         if (!enter_repo(dir, 0))
 285                 not_found("Not a git repository: '%s'", dir);
 286
 287         cmd->imp(cmd_arg);
 288         return 0;
 289 }