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fix: Add Defensive Code when Building URL Signatures #656

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Merged
BrandonStalnaker merged 1 commit into from
Mar 11, 2026
Merged

fix: Add Defensive Code when Building URL Signatures #656

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19 changes: 19 additions & 0 deletions UnitTests/ObjCTests/MPURLRequestBuilderTests.m
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,25 @@ - (void)testURLRequestComposition {
}
}

- (void)testBuildReturnsNilWhenConfigQueryExceedsMaxLength {
NSMutableString *longQueryValue = [NSMutableString stringWithCapacity:9000];
for (NSInteger i = 0; i < 9000; i++) {
[longQueryValue appendString:@"a"];
}

NSString *urlString = [NSString stringWithFormat:@"https://config2.mparticle.com/v4/unit_test_app_key/config?plan_id=%@", longQueryValue];
NSURL *defaultURL = [NSURL URLWithString:urlString];
NSURL *modifiedURL = [NSURL URLWithString:urlString];
XCTAssertNotNil(defaultURL);
XCTAssertNotNil(modifiedURL);

MPURL *url = [[MPURL alloc] initWithURL:modifiedURL defaultURL:defaultURL];
MPURLRequestBuilder *builder = [MPURLRequestBuilder newBuilderWithURL:url message:nil httpMethod:@"GET"];
NSMutableURLRequest *request = [builder build];

XCTAssertNil(request);
}

- (void)testEtag {
NSDictionary *configuration1 = @{
@"id":@42,
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46 changes: 42 additions & 4 deletions mParticle-Apple-SDK/Network/MPURLRequestBuilder.m
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,8 @@ @interface MPURLRequestBuilder() {

@end

static const NSUInteger kMPURLRequestBuilderMaxQueryLength = 8192;


@implementation MPURLRequestBuilder

Expand Down Expand Up @@ -161,11 +163,29 @@ - (NSMutableURLRequest *)build {
return nil;
}
NSString *audienceQuery = [urlRequest.URL query];
if (audienceQuery.length > kMPURLRequestBuilderMaxQueryLength) {
MPILogError(@"Cannot build URL request — audience query exceeds max supported length");
return nil;
}
NSString *audienceSignature;
if (audienceQuery) {
audienceSignature = [NSString stringWithFormat:@"%@\n%@\n%@?%@", _httpMethod, date, audienceRelativePath, audienceQuery];
NSMutableString *signatureBuilder = [NSMutableString stringWithCapacity:_httpMethod.length + date.length + audienceRelativePath.length + audienceQuery.length + 4];
[signatureBuilder appendString:_httpMethod ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:date ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:audienceRelativePath];
[signatureBuilder appendString:@"?"];
[signatureBuilder appendString:audienceQuery];
audienceSignature = [signatureBuilder copy];
} else {
audienceSignature = [NSString stringWithFormat:@"%@\n%@\n%@", _httpMethod, date, audienceRelativePath];
NSMutableString *signatureBuilder = [NSMutableString stringWithCapacity:_httpMethod.length + date.length + audienceRelativePath.length + 3];
[signatureBuilder appendString:_httpMethod ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:date ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:audienceRelativePath];
audienceSignature = [signatureBuilder copy];
}
MPILogVerbose(@"Audience Signature:\n%@", audienceSignature);
NSString *hmacSha256Encode = [self hmacSha256Encode:audienceSignature key:secret];
Expand Down Expand Up @@ -243,10 +263,28 @@ - (NSMutableURLRequest *)build {
}

NSString *query = [_url.defaultURL query];
if (query.length > kMPURLRequestBuilderMaxQueryLength) {
MPILogError(@"Cannot build URL request — config query exceeds max supported length");
return nil;
}
if (query) {
signatureMessage = [NSString stringWithFormat:@"%@\n%@\n%@?%@", _httpMethod, date, relativePath, query];
NSMutableString *signatureBuilder = [NSMutableString stringWithCapacity:_httpMethod.length + date.length + relativePath.length + query.length + 4];
[signatureBuilder appendString:_httpMethod ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:date ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:relativePath];
[signatureBuilder appendString:@"?"];
[signatureBuilder appendString:query];
signatureMessage = [signatureBuilder copy];
} else {
signatureMessage = [NSString stringWithFormat:@"%@\n%@\n%@", _httpMethod, date, relativePath];
NSMutableString *signatureBuilder = [NSMutableString stringWithCapacity:_httpMethod.length + date.length + relativePath.length + 3];
[signatureBuilder appendString:_httpMethod ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:date ?: @""];
[signatureBuilder appendString:@"\n"];
[signatureBuilder appendString:relativePath];
signatureMessage = [signatureBuilder copy];
}
}

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