92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
#include "websocket.h"
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#include "http.h"
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#include <nettle/sha1.h>
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#include <nettle/base64.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdbool.h>
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#include <ctype.h>
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static const char magic_uuid[] = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
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static void tolower_and_remove_ws(char* dst, const char* src)
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{
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while (*src)
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if (!isspace(*src))
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*dst++ = tolower(*src++);
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*dst = '\0';
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}
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// TODO: Do some more sanity checks on the input
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ssize_t ws_handshake(char* output, size_t output_maxlen, const char* input)
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{
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bool ok = false;
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struct http_req req = {};
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if (http_req_parse(&req, input) < 0)
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return -1;
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char protocols[256] = ",";
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char versions[256] = ",";
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char tmpstring[256];
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const char *challenge = NULL;
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for (size_t i = 0; i < req.field_index; ++i) {
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if (strcasecmp(req.field[i].key, "Sec-WebSocket-Key") == 0) {
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challenge = req.field[i].value;
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}
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if (strcasecmp(req.field[i].key, "Sec-WebSocket-Protocol") == 0) {
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snprintf(tmpstring, sizeof(tmpstring), "%s%s,",
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protocols, req.field[i].value);
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tolower_and_remove_ws(protocols, tmpstring);
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}
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if (strcasecmp(req.field[i].key, "Sec-WebSocket-Version") == 0) {
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snprintf(tmpstring, sizeof(tmpstring), "%s%s,",
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versions, req.field[i].value);
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tolower_and_remove_ws(versions, tmpstring);
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}
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}
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if (!challenge)
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goto failure;
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bool have_protocols = strlen(protocols) != 1;
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bool have_versions = strlen(versions) != 1;
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if (have_protocols && !strstr(protocols, ",chat,"))
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goto failure;
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if (have_versions && !strstr(versions, ",13,"))
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goto failure;
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struct sha1_ctx ctx;
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sha1_init(&ctx);
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sha1_update(&ctx, strlen(challenge), (const uint8_t*)challenge);
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sha1_update(&ctx, strlen(magic_uuid), (const uint8_t*)magic_uuid);
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uint8_t hash[SHA1_DIGEST_SIZE];
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sha1_digest(&ctx, sizeof(hash), hash);
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char response[BASE64_ENCODE_RAW_LENGTH(SHA1_DIGEST_SIZE) + 1] = {};
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base64_encode_raw(response, SHA1_DIGEST_SIZE, hash);
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size_t len = snprintf(output, output_maxlen,
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"HTTP/1.1 101 Switching Protocols\r\n"
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"Upgrade: websocket\r\n"
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"Connection: Upgrade\r\n"
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"Sec-WebSocket-Accept: %s\r\n"
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"%s%s"
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"\r\n",
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response,
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have_protocols ? "Sec-WebSocket-Protocol: char\r\n" : "",
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have_versions ? "Sec-WebSocket-Version: 13\r\n" : "");
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ssize_t header_len = req.header_length;
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ok = len < output_maxlen;
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failure:
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http_req_free(&req);
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return ok ? header_len : -1;
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}
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