1 /* 2 This is an example of how to hook up evhttp with bufferevent_ssl 3 4 It just GETs an https URL given on the command-line and prints the response 5 body to stdout. 6 7 Actually, it also accepts plain http URLs to make it easy to compare http vs 8 https code paths. 9 10 Loosely based on le-proxy.c. 11 */ 12 13 #include <stdio.h> 14 #include <assert.h> 15 #include <stdlib.h> 16 #include <string.h> 17 #include <errno.h> 18 19 #ifdef WIN32 20 #include <winsock2.h> 21 #include <ws2tcpip.h> 22 #else 23 #include <sys/socket.h> 24 #include <netinet/in.h> 25 #endif 26 27 #include <event2/bufferevent_ssl.h> 28 #include <event2/bufferevent.h> 29 #include <event2/buffer.h> 30 #include <event2/listener.h> 31 #include <event2/util.h> 32 #include <event2/http.h> 33 #include <event2/http_struct.h> 34 35 #include <openssl/ssl.h> 36 #include <openssl/err.h> 37 #include <openssl/rand.h> 38 39 static struct event_base *base; 40 41 static void 42 http_request_done(struct evhttp_request *req, void *ctx) 43 { 44 char buffer[256]; 45 int nread; 46 47 if (req == NULL) { 48 /* If req is NULL, it means an error occurred, but 49 * sadly we are mostly left guessing what the error 50 * might have been. We'll do our best... */ 51 struct bufferevent *bev = (struct bufferevent *) ctx; 52 unsigned long oslerr; 53 int printed_err = 0; 54 int errcode = EVUTIL_SOCKET_ERROR(); 55 fprintf(stderr, "some request failed - no idea which one though!\n"); 56 /* Print out the OpenSSL error queue that libevent 57 * squirreled away for us, if any. */ 58 while ((oslerr = bufferevent_get_openssl_error(bev))) { 59 ERR_error_string_n(oslerr, buffer, sizeof(buffer)); 60 fprintf(stderr, "%s\n", buffer); 61 printed_err = 1; 62 } 63 /* If the OpenSSL error queue was empty, maybe it was a 64 * socket error; let's try printing that. */ 65 if (! printed_err) 66 fprintf(stderr, "socket error = %s (%d)\n", 67 evutil_socket_error_to_string(errcode), 68 errcode); 69 return; 70 } 71 72 fprintf(stderr, "Response line: %d %s\n", 73 req->response_code, req->response_code_line); 74 75 while ((nread = evbuffer_remove(req->input_buffer, buffer, sizeof(buffer))) 76 > 0) { 77 /* These are just arbitrary chunks of 256 bytes. 78 * They are not lines, so we can't treat them as such. */ 79 fwrite(buffer, nread, 1, stdout); 80 } 81 } 82 83 static void 84 syntax(void) 85 { 86 fputs("Syntax:\n", stderr); 87 fputs(" https-client <https-url>\n", stderr); 88 fputs("Example:\n", stderr); 89 fputs(" https-client https://ip.appspot.com/\n", stderr); 90 91 exit(1); 92 } 93 94 static void 95 die(const char *msg) 96 { 97 fputs(msg, stderr); 98 exit(1); 99 } 100 101 static void 102 die_openssl(const char *func) 103 { 104 fprintf (stderr, "%s failed:\n", func); 105 106 /* This is the OpenSSL function that prints the contents of the 107 * error stack to the specified file handle. */ 108 ERR_print_errors_fp (stderr); 109 110 exit(1); 111 } 112 113 int 114 main(int argc, char **argv) 115 { 116 int r; 117 118 struct evhttp_uri *http_uri; 119 const char *url, *scheme, *host, *path, *query; 120 char uri[256]; 121 int port; 122 123 SSL_CTX *ssl_ctx; 124 SSL *ssl; 125 struct bufferevent *bev; 126 struct evhttp_connection *evcon; 127 struct evhttp_request *req; 128 129 if (argc != 2) 130 syntax(); 131 132 url = argv[1]; 133 http_uri = evhttp_uri_parse(url); 134 if (http_uri == NULL) { 135 die("malformed url"); 136 } 137 138 scheme = evhttp_uri_get_scheme(http_uri); 139 if (scheme == NULL || (strcasecmp(scheme, "https") != 0 && 140 strcasecmp(scheme, "http") != 0)) { 141 die("url must be http or https"); 142 } 143 144 host = evhttp_uri_get_host(http_uri); 145 if (host == NULL) { 146 die("url must have a host"); 147 } 148 149 port = evhttp_uri_get_port(http_uri); 150 if (port == -1) { 151 port = (strcasecmp(scheme, "http") == 0) ? 80 : 443; 152 } 153 154 path = evhttp_uri_get_path(http_uri); 155 if (path == NULL) { 156 path = "/"; 157 } 158 159 query = evhttp_uri_get_query(http_uri); 160 if (query == NULL) { 161 snprintf(uri, sizeof(uri) - 1, "%s", path); 162 } else { 163 snprintf(uri, sizeof(uri) - 1, "%s?%s", path, query); 164 } 165 uri[sizeof(uri) - 1] = '\0'; 166 167 // Initialize OpenSSL 168 SSL_library_init(); 169 ERR_load_crypto_strings(); 170 SSL_load_error_strings(); 171 OpenSSL_add_all_algorithms(); 172 173 /* This isn't strictly necessary... OpenSSL performs RAND_poll 174 * automatically on first use of random number generator. */ 175 r = RAND_poll(); 176 if (r == 0) { 177 die_openssl("RAND_poll"); 178 } 179 180 /* Create a new OpenSSL context */ 181 ssl_ctx = SSL_CTX_new(SSLv23_method()); 182 if (!ssl_ctx) 183 die_openssl("SSL_CTX_new"); 184 185 /* Attempt to use the system's trusted root certificates. 186 * (This path is only valid for Debian-based systems.) */ 187 if (1 != SSL_CTX_load_verify_locations(ssl_ctx, 188 "/etc/ssl/certs/ca-certificates.crt", 189 NULL)) 190 die_openssl("SSL_CTX_load_verify_locations"); 191 SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, NULL); 192 193 // Create event base 194 base = event_base_new(); 195 if (!base) { 196 perror("event_base_new()"); 197 return 1; 198 } 199 200 // Create OpenSSL bufferevent and stack evhttp on top of it 201 ssl = SSL_new(ssl_ctx); 202 if (ssl == NULL) { 203 die_openssl("SSL_new()"); 204 } 205 206 if (strcasecmp(scheme, "http") == 0) { 207 bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE); 208 } else { 209 bev = bufferevent_openssl_socket_new(base, -1, ssl, 210 BUFFEREVENT_SSL_CONNECTING, 211 BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS); 212 } 213 214 if (bev == NULL) { 215 fprintf(stderr, "bufferevent_openssl_socket_new() failed\n"); 216 return 1; 217 } 218 219 bufferevent_openssl_set_allow_dirty_shutdown(bev, 1); 220 221 // For simplicity, we let DNS resolution block. Everything else should be 222 // asynchronous though. 223 evcon = evhttp_connection_base_bufferevent_new(base, NULL, bev, 224 host, port); 225 if (evcon == NULL) { 226 fprintf(stderr, "evhttp_connection_base_bufferevent_new() failed\n"); 227 return 1; 228 } 229 230 // Fire off the request 231 req = evhttp_request_new(http_request_done, bev); 232 if (req == NULL) { 233 fprintf(stderr, "evhttp_request_new() failed\n"); 234 return 1; 235 } 236 237 evhttp_add_header(req->output_headers, "Host", host); 238 evhttp_add_header(req->output_headers, "Connection", "close"); 239 240 r = evhttp_make_request(evcon, req, EVHTTP_REQ_GET, uri); 241 if (r != 0) { 242 fprintf(stderr, "evhttp_make_request() failed\n"); 243 return 1; 244 } 245 246 event_base_dispatch(base); 247 248 evhttp_connection_free(evcon); 249 event_base_free(base); 250 251 return 0; 252 } 253