commit a38f7c277142e5300f3d7f43567b38706d727010 Author: Karsten Loesing karsten.loesing@gmx.net Date: Wed Oct 25 17:29:40 2017 +0200

Handle bridge descriptors with unusual line order.

Typically, the "published" line appears before the "fingerprint" line. However, an alternative Tor implementation orders these two lines differently, which is valid due to the spec. We need to handle this case by accepting lines in either order.

Fixes #23981. --- .../bridgedescs/SanitizedBridgesWriter.java | 77 +++++++++++++++++----- 1 file changed, 59 insertions(+), 18 deletions(-)

diff --git a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java index f53a3d1..441eb01 100644 --- a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java +++ b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java @@ -679,6 +679,7 @@ public class SanitizedBridgesWriter extends CollecTorMain { new String(data, "US-ASCII"))); StringBuilder scrubbed = new StringBuilder(); String line = null; + byte[] fingerprintBytes = null; String hashedBridgeIdentity = null; String address = null; String routerLine = null; @@ -734,6 +735,20 @@ public class SanitizedBridgesWriter extends CollecTorMain { this.haveWarnedAboutInterval = true; } } + if (null != fingerprintBytes) { + /* We have read both published and fingerprint lines that we need to + * scrub the bridge's address which we might need to scrub reject + * lines. */ + try { + scrubbedAddress = scrubIpv4Address(address, fingerprintBytes, + published); + } catch (IOException e) { + /* There's a persistence problem, so we shouldn't scrub more + * IP addresses in this execution. */ + this.persistenceProblemWithSecrets = true; + return; + } + } scrubbed.append(line + "\n");

/* Parse the fingerprint to determine the hashed bridge @@ -743,13 +758,51 @@ public class SanitizedBridgesWriter extends CollecTorMain { String fingerprint = line.substring(line.startsWith("opt ") ? "opt fingerprint".length() : "fingerprint".length()) .replaceAll(" ", "").toLowerCase(); - byte[] fingerprintBytes = Hex.decodeHex( - fingerprint.toCharArray()); + fingerprintBytes = Hex.decodeHex(fingerprint.toCharArray()); hashedBridgeIdentity = DigestUtils.sha1Hex(fingerprintBytes) .toLowerCase(); + if (null != published) { + /* We have read both published and fingerprint lines that we need to + * scrub the bridge's address which we might need to scrub reject + * lines. */ + try { + scrubbedAddress = scrubIpv4Address(address, fingerprintBytes, + published); + } catch (IOException e) { + /* There's a persistence problem, so we shouldn't scrub more + * IP addresses in this execution. */ + this.persistenceProblemWithSecrets = true; + return; + } + } + scrubbed.append((line.startsWith("opt ") ? "opt " : "") + + "fingerprint"); + for (int i = 0; i < hashedBridgeIdentity.length() / 4; i++) { + scrubbed.append(" " + hashedBridgeIdentity.substring(4 * i, + 4 * (i + 1)).toUpperCase()); + } + scrubbed.append("\n"); + + /* Replace the contact line (if present) with a generic one. */ + } else if (line.startsWith("contact ")) { + scrubbed.append("contact somebody\n"); + + /* When we reach the signature, we're done. Write the sanitized + * descriptor to disk below. */ + } else if (line.startsWith("router-signature")) { + + /* Write the scrubbed "router" line now based on the "router", + * "fingerprint", and "published" lines that we read before. Also + * scrub any "or-address" lines. */ + if (null == routerLine || null == fingerprintBytes + || null == published) { + logger.warn("Missing either of the following lines that are " + + "required to sanitize this server bridge descriptor: " + + ""router", "fingerprint", "published". Skipping " + + "descriptor."); + return; + } try { - scrubbedAddress = scrubIpv4Address(address, fingerprintBytes, - published); if (orAddresses != null) { scrubbedOrAddresses = new ArrayList<>(); for (String orAddress : orAddresses) { @@ -781,21 +834,9 @@ public class SanitizedBridgesWriter extends CollecTorMain { this.persistenceProblemWithSecrets = true; return; } - scrubbed.append((line.startsWith("opt ") ? "opt " : "") - + "fingerprint"); - for (int i = 0; i < hashedBridgeIdentity.length() / 4; i++) { - scrubbed.append(" " + hashedBridgeIdentity.substring(4 * i, - 4 * (i + 1)).toUpperCase()); - } - scrubbed.append("\n");

- /* Replace the contact line (if present) with a generic one. */ - } else if (line.startsWith("contact ")) { - scrubbed.append("contact somebody\n"); - - /* When we reach the signature, we're done. Write the sanitized - * descriptor to disk below. */ - } else if (line.startsWith("router-signature")) { + /* Put together the scrubbed descriptor from "router" to the newline + * before the original "router-signature" line. */ scrubbedDesc = scrubbedRouterLine; if (scrubbedOrAddresses != null) { for (String scrubbedOrAddress : scrubbedOrAddresses) {